EP2497089A2 - Procédés et systèmes pour la migration d'assemblages combustibles dans un réacteur à fission nucléaire - Google Patents

Procédés et systèmes pour la migration d'assemblages combustibles dans un réacteur à fission nucléaire

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Publication number
EP2497089A2
EP2497089A2 EP10844848A EP10844848A EP2497089A2 EP 2497089 A2 EP2497089 A2 EP 2497089A2 EP 10844848 A EP10844848 A EP 10844848A EP 10844848 A EP10844848 A EP 10844848A EP 2497089 A2 EP2497089 A2 EP 2497089A2
Authority
EP
European Patent Office
Prior art keywords
nuclear fission
locations
dimension
traveling wave
fission fuel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP10844848A
Other languages
German (de)
English (en)
Inventor
Ehud Greenspan
Roderick A. Hyde
Robert C. Petroski
Joshua C. Walter
Thomas A. Weaver
Charles Whitmer
Lowell L. Wood, Jr.
George B. Zimmerman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
TerraPower LLC
Original Assignee
Searete LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US12/590,448 external-priority patent/US10008294B2/en
Priority claimed from US12/657,735 external-priority patent/US9786392B2/en
Priority claimed from US12/657,725 external-priority patent/US9922733B2/en
Priority claimed from US12/657,726 external-priority patent/US9799416B2/en
Application filed by Searete LLC filed Critical Searete LLC
Publication of EP2497089A2 publication Critical patent/EP2497089A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C7/00—Control of nuclear reaction
    • G21C7/06—Control of nuclear reaction by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C19/00—Arrangements for treating, for handling, or for facilitating the handling of, fuel or other materials which are used within the reactor, e.g. within its pressure vessel
    • G21C19/20—Arrangements for introducing objects into the pressure vessel; Arrangements for handling objects within the pressure vessel; Arrangements for removing objects from the pressure vessel
    • G21C19/205—Interchanging of fuel elements in the core, i.e. fuel shuffling
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C1/00—Reactor types
    • G21C1/02—Fast fission reactors, i.e. reactors not using a moderator ; Metal cooled reactors; Fast breeders
    • G21C1/022—Fast fission reactors, i.e. reactors not using a moderator ; Metal cooled reactors; Fast breeders characterised by the design or properties of the core
    • G21C1/026—Reactors not needing refueling, i.e. reactors of the type breed-and-burn, e.g. travelling or deflagration wave reactors or seed-blanket reactors
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21D—NUCLEAR POWER PLANT
    • G21D3/00—Control of nuclear power plant
    • G21D3/001—Computer implemented control
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • the present application relates to methods and systems for migrating fuel assemblies in a nuclear fission reactor.
  • the present application is related to and claims the benefit of the earliest available effective filing date(s) from the following listed application(s) (the "Related Applications") (e.g., claims earliest available priority dates for other than provisional patent applications or claims benefits under 35 USC ⁇ 119(e) for provisional patent applications, for any and all parent, grandparent, great-grandparent, etc. applications of the Related Application(s)). All subject matter of the Related Applications and of any and all parent, grandparent, great-grandparent, etc. applications of the Related Applications, including any priority claims, is incorporated herein by reference to the extent such subject matter is not inconsistent herewith.
  • Illustrative embodiments provide methods and systems for migrating fuel assemblies in a nuclear fission reactor, methods of operating a nuclear fission traveling wave reactor, methods of controlling a nuclear fission traveling wave reactor, systems for controlling a nuclear fission traveling wave reactor, computer software program products for controlling a nuclear fission traveling wave reactor, and nuclear fission traveling wave reactors with systems for migrating fuel assemblies.
  • FIG. 1A is a block diagram of an illustrative method of operating a nuclear fission traveling wave reactor.
  • FIGS. IB - ID are perspective views in partial schematic form of components of illustrative nuclear fission reactor cores.
  • FIGS. IE - 1H illustrate effects on shape of a nuclear fission traveling wave burnfront by migration of selected nuclear fission fuel subassemblies
  • FIG. II is a block diagram of a detail of part of the method of FIG. 1A.
  • FIG. 1J illustrates rotation of a nuclear fission fuel subassembly.
  • FIG. IK is a block diagram of a detail of part of the method of FIG. 1A.
  • FIG. 1L illustrates inversion of a nuclear fission fuel subassembly.
  • FIGS. 1M - IN are block diagrams of details of part of the method of FIG. 1A.
  • FIG. lO illustrates spiral migration of a nuclear fission fuel subassembly.
  • FIG. IP is a block diagram of a detail of part of the method of FIG. 1A.
  • FIG. 1Q illustrates axial migration of a nuclear fission fuel subassembly.
  • FIG. 1R illustrates a substantially spherical shape of a nuclear fission traveling wave burnfront.
  • FIG. IS illustrates a continuously curved surface of a nuclear fission traveling wave burnfront.
  • FIG. IT illustrates a substantially rotationally symmetrical shape of a nuclear fission traveling wave burnfront.
  • FIGS. 1U - IV illustrate substantial n-fold rotational symmetry of a shape of a nuclear fission traveling wave burnfront.
  • FIG. 1W illustrates an asymmetrical shape of a nuclear fission traveling wave burnfront.
  • FIGS. IX - 1AF are block diagrams of details of parts of the method of FIG. 1A.
  • FIG. 2A is a block diagram of an illustrative method of controlling a nuclear fission traveling wave reactor.
  • FIGS. 2B - 2M are block diagrams of details of parts of the method of FIG. 2 A.
  • FIG. 3A is a block diagram of an illustrative system for determining migration of nuclear fission fuel subassemblies.
  • FIGS. 3B - 3C are block diagrams of details of components of the system of FIG.
  • FIG. 4A is a block diagram of an illustrative system for migrating nuclear fission fuel subassemblies.
  • FIGS. 4B - 4C are block diagrams of details of components of the system of FIG.
  • FIG. 5 is block diagram in partial schematic form of an illustrative nuclear fission traveling wave reactor.
  • FIG. 6A is a flow chart of an illustrative method of operating a nuclear fission traveling wave reactor.
  • FIG. 6B is a block diagram of a detail of part of the method of FIG. 6A.
  • FIG. 7 is a flow chart of an illustrative method of operating a nuclear fission traveling wave reactor.
  • FIG. 8 is a flow chart of an illustrative method of operating a nuclear fission traveling wave reactor.
  • FIG. 9 is a flow chart of an illustrative method of operating a nuclear fission traveling wave reactor.
  • FIG. 10A is a flow chart of an illustrative method of operating a nuclear fission reactor.
  • FIGS. 10B - 10D are block diagrams of details of parts of the method of FIG.
  • Illustrative embodiments provide methods and systems for migrating fuel assemblies in a nuclear fission reactor, methods of operating a nuclear fission traveling wave reactor, methods of controlling a nuclear fission traveling wave reactor, systems for controlling a nuclear fission traveling wave reactor, computer software program products for controlling a nuclear fission traveling wave reactor, and nuclear fission traveling wave reactors with systems for migrating fuel assemblies.
  • a nuclear fission traveling wave is also known as a nuclear fission deflagration wave, for sake of clarity reference will be made herein to a nuclear fission traveling wave. Portions of the following discussion include information excerpted from a paper entitled "Completely Automated Nuclear Power Reactors For Long-Term Operation: III.
  • nuclear fission fuels envisioned for use in nuclear fission traveling wave reactors are typically widely available, such as without limitation uranium (natural, depleted, or enriched), thorium, plutonium, or even previously-burned nuclear fission fuel assemblies.
  • Other, less widely available nuclear fission fuels such as without limitation other actinide elements or isotopes thereof may also be used.
  • Some nuclear fission traveling wave reactors contemplate long-term operation at full power on the order of around 1/3 century to around 1/2 century or longer.
  • nuclear fission traveling wave reactors do not contemplate nuclear refueling (but instead contemplate burial in-place at end-of-life) while some other nuclear fission traveling wave reactors contemplate nuclear refueling - with some nuclear refueling occurring during shutdown and some nuclear refueling occurring during operation at power. It is also contemplated that nuclear fission fuel reprocessing may be avoided in some cases, thereby mitigating possibilities for diversion to military uses and other issues.
  • Simultaneously accommodating desires to achieve 1/3 - 1/2 century (or longer) of operations at full power without nuclear refueling and to avoid nuclear fission fuel reprocessing may entail use of a fast neutron spectrum.
  • propagating a nuclear fission traveling wave permits a high average burn-up of non-enriched actinide fuels, such as natural uranium or thorium, and use of a comparatively small "nuclear fission igniter" region of moderate isotopic enrichment of nuclear fissionable materials in the core's fuel charge.
  • a nuclear fission traveling wave reactor core suitably can include a nuclear fission igniter and a larger nuclear fission deflagration burn-wave-propagating region.
  • the nuclear fission deflagration burn-wave-propagating region suitably contains thorium or uranium fuel, and functions on the general principle of fast neutron spectrum fission breeding.
  • a nuclear fission traveling wave reactor core suitably is a breeder for reasons of efficient nuclear fission fuel utilization and of minimization of requirements for isotopic enrichment.
  • a fast neutron spectrum suitably is used because the. high absorption cross-section of fission products for thermal neutrons typically does not permit high fuel utilization of thorium or of the more abundant uranium isotope, 238 U, in uranium-fueled embodiments, without removal of fission products.
  • Propagation of deflagration burning- waves through nuclear fission fuel materials can release power at predictable levels. Moreover, if the material configuration has sufficiently time-invariant features such as configurations found in typical commercial power-producing nuclear reactors, then ensuing power production may be at a steady level. Finally, if traveling wave propagation-speed may be externally modulated in a practical manner, the energy release-rate and thus power production may be controlled as desired.
  • Nucleonics of the nuclear fission traveling wave are explained below. Inducing nuclear fission of selected isotopes of the actinide elements - the fissile ones - by absorption of neutrons of any energy may permit the release of nuclear binding energy at any material temperature, including arbitrarily low ones.
  • the neutrons that are absorbed by the fissile actinide element may be provided by the nuclear fission igniter.
  • Release of more than two neutrons for every neutron which is absorbed may permit first converting an atom of a non-fissile isotope to a fissile one (via neutron capture and subsequent beta-decay) by an initial neutron capture, and then additionally permit neutron-fissioning the nucleus of the newly-created fissile isotope in the course of a second neutron fission absorption.
  • Most high-Z (Z > 90) nuclear species can be used as nuclear fission fuel material in a traveling wave reactor (or a breeder reactor) if, on the average, one neutron from a given nuclear fission event can be radiatively captured on a non-fissile-but-'fertile' nucleus which will then convert (such as via beta-decay) into a fissile nucleus and a second neutron from the same fission event can be captured on a fissile nucleus and, thereby, induce fission.
  • a traveling wave reactor or a breeder reactor
  • a characteristic speed of wave advance is, therefore, limited by the half-lives on the order of days or months.
  • a characteristic speed of wave advance may be on the order of the ratio of the distance traveled by a neutron from its fission-birth to its radiative capture on a fertile nucleus (that is, a mean free path) to the half-life of the (longest-lived nucleus in the chain of) beta-decay leading from the fertile nucleus to the fissile one.
  • Such a relatively slow speed-of-advance indicates that the wave can be characterized as a traveling wave or a deflagration wave, rather than a detonation wave.
  • the traveling wave attempts to accelerate, its leading-edge counters ever-more- pure fertile material (which is relatively lossy in a neutronic sense), for the concentration of fissile nuclei well ahead of the center of the wave becomes exponentially low.
  • the wave's leading-edge (referred to herein as a "burnfront") stalls or slows.
  • the wave slows and the conversion ratio is maintained greater than one (that is, breeding rate is greater than fissioning rate)
  • the local concentration of fissile nuclei arising from continuing beta-decay increases, the local rates of fission and neutron production rise, and the wave's leading-edge, that is the burnfront, accelerates.
  • the propagation may take place at an arbitrarily low material temperature - although the temperatures of both the neutrons and the fissioning nuclei may be around 1 MeV.
  • fissile isotopes of actinide elements are rare terrestrially, both absolutely and relative to fertile isotopes of these elements, fissile isotopes can be concentrated, enriched and synthesized. For example, the
  • Th or U if the neutron spectrum in the wave is a 'hard' or 'fast' one. That is, if the neutrons which carry the chain reaction in the wave have energies which are not very small compared to the approximately 1 MeV at which they are evaporated from nascent fission fragments, then relatively large losses to the spacetime-local neutron economy can be avoided when the local mass-fraction of fission products becomes comparable to that of the fertile material (recalling that a single mole of fissile material fission-converts to two moles of fission-product nuclei). Even neutronic losses to typical neutron-reactor structural materials, such as Ta, which has desirable high-temperature properties, may become substantial at neutron energies ⁇ 0.1 MeV.
  • the algebraic sign of the function a(v - 2) constitutes a condition for the feasibility of nuclear fission traveling wave propagation in fertile material compared with the overall fissile isotopic mass budget, in the absence of neutron leakage from the core or parasitic absorptions (such as on fission products) within its body, for each of the fissile isotopes of the reactor core.
  • the algebraic sign is generally positive for all fissile isotopes of interest, from fission neutron-energies of approximately 1 MeV down into the resonance capture region.
  • the quantity a(v - 2)/v upper-bounds the fraction of total fission-born neutrons which may be lost to leakage, parasitic absorption, or geometric divergence during traveling wave propagation. It is noted that this fraction is 0.15-0.30 for the major fissile isotopes over the range of neutron energies which prevails in all effectively unmoderated actinide isotopic configurations of practical interest (approximately 0.1-1.5 MeV).
  • fissile element generation by capture on fertile isotopes is favored over fission-product capture by 0.7-1.5 orders-of-magnitude over the neutron energy range 0.1-1.5 MeV.
  • the former suggests that fertile-to-fissile conversion will be feasible only to the extent of 1.5-5% percent at-or-near thermal neutron energies, while the latter indicates that conversions in excess of 50% may be expected for near- fission energy neutron spectra.
  • Th and U are relatively abundant terrestrially: Th and U, the exclusive and the principal (that is, longest-lived) isotopic components of naturally-occurring thorium and uranium, respectively.
  • fission neutrons in these actinide isotopes will likely result in either capture on a fertile isotopic nucleus or fission of a fissile one before neutron energy has decreased significantly below 0.1 MeV (and thereupon becomes susceptible with non-negligible likelihood to capture on a fission-product nucleus).
  • fission product nuclei concentrations can approach or in some circumstances exceed fertile ones and fissile nuclear concentrations may be an order-of- magnitude less than the lesser of fission-product or fertile ones while remaining quantitatively substantially reliable.
  • the breeding-and-burning wave provides sufficient excess neutrons to breed new fissile material 1-2 mean-free-paths into the yet-unburned fuel, effectively replacing the fissile fuel burnt in the wave.
  • the 'ash' behind the burn- wave's peak is substantially 'neutronically neutral', since the neutronic reactivity of its fissile fraction is just balanced by the parasitic absorptions of structure and fission product inventories on top of leakage. If the fissile atom inventory in the wave's center and just in advance of it is time- stationary as the wave propagates, then it is doing so stably; if less, then the wave is 'dying', while if more, the wave may be said to be 'accelerating.'
  • a nuclear fission traveling wave may be propagated and maintained in substantially steady-state conditions for long time intervals in configurations of naturally- occurring actinide isotopes.
  • Propagation of a nuclear fission traveling wave has implications for embodiments of nuclear fission traveling wave reactors.
  • local material temperature feedback can be imposed on the local nuclear reaction rate at an acceptable expense in the traveling wave's neutron economy.
  • Such a large negative temperature coefficient of neutronic reactivity confers an ability to control the speed-of-advance of the traveling wave. If very little thermal power is extracted from the burning fuel, its temperature rises and the temperature-dependent reactivity falls, and the nuclear fission rate at wave-center becomes correspondingly small and the wave's equation-of-time reflects only a very small axial rate-of-advance.
  • reactivity control systems such as without limitation neutron-absorbing material in control rods or local material-temperature thermostating modules, may use around 5-10% of the total fission neutron production in the nuclear fission traveling wave reactor 10.
  • Another ⁇ 10% of the total fission neutron production in a nuclear fission traveling wave reactor may be lost to parasitic absorption in the high- performance, high temperature, structure materials (such as Ta, W, or Re) employed in structural components of the nuclear fission traveling wave reactor.
  • the Zs of these materials are approximately 80% of that of the actinides, and thus their radiative capture cross- sections for high-energy neutrons are not particularly small compared to those of the actinides.
  • a final 5-10% of the total fission neutron production in a nuclear fission traveling wave reactor may be lost to parasitic absorption in fission products.
  • the spectrum may be similar to that of a sodium-cooled fast reactor in that parasitic absorption may account for only around a 1-2% loss.
  • the neutron economy characteristically is sufficiently rich that approximately 70% of total fission neutron production is sufficient to sustain traveling wave-propagation in the absence of leakage and rapid geometric divergence.
  • the neutron flux from the most intensely burning region behind the burnfront breeds a fissile isotope-rich region at the bumfront' s leading-edge, thereby serving to advance the nuclear fission traveling wave.
  • the nuclear fission traveling wave's burnfront has swept over a given mass of fuel, the fissile atom concentration continues to rise for as long as radiative capture of neutrons on available fertile nuclei is considerably more likely than on fission product nuclei, while ongoing fission generates an ever-greater mass of fission products.
  • Nuclear power-production density peaks in this region of the fuel-charge, at any given moment.
  • the concentration ratio of fission product nuclei (whose mass closely averages half that of a fissile nucleus) to fissile ones climbs to a value comparable to the ratio of the fissile fission to the fission product radiative capture cross-sections.
  • the "local neutronic reactivity" thereupon approaches a negative value or, in some embodiments may become negative. Hence, both burning and breeding effectively cease.
  • non-fissile neutron absorbing material such as boron carbide, hafnium, or gadolinium may be added to ensure the "local neutronic reactivity" is negative.
  • all the nuclear fission fuel ever used in the reactor is installed during manufacture of the reactor core assembly. Also, in some configurations no spent fuel is ever removed from the reactor core assembly. In one approach, such embodiments may allow operation without ever accessing the reactor core after nuclear fission ignition up to and perhaps after completion of propagation of the burnfront.
  • all the nuclear fission fuel ever used in the reactor is installed during manufacture of the reactor core assembly and in some configurations no spent fuel is ever removed from the reactor core assembly.
  • at least some of the nuclear fission fuel may be migrated or shuffled between or among locations within a reactor core. Such migration or shuffling of at least some of the nuclear fission fuel may be performed to achieve objectives as discussed below.
  • nuclear fission traveling wave reactors additional nuclear fission fuel may be added to the reactor core assembly after nuclear fission ignition.
  • spent fuel may be removed from the reactor core assembly (and, in some embodiments, removal of spent fuel from the reactor core assembly may be performed while the nuclear fission traveling wave reactor is operating at power).
  • RODERICK A. HYDE MURIEL Y. ISHI AWA
  • NATHAN P. MYHRVOLD AND LOWELL L.
  • Th or U fuel-charges can initiate with 'nuclear fission igniter modules', such as without limitation nuclear fission fuel assemblies that are enriched in fissile isotopes.
  • Illustrative nuclear fission igniter modules and methods for launching nuclear fission traveling waves are discussed in detail in a co-pending United States Patent Application No. 12/069,908, entitled NUCLEAR FISSION IGNITER naming CHARLES E. AHLFELD, JOHN ROGERS GILLELAND, RODERICK A. HYDE, MURIEL Y. ISHIKAWA, DAVID G. MCALEES, NATHAN P. MYHRVOLD, CHARLES WHITMER, AND LOWELL L. WOOD, JR.
  • nuclear fission igniter module design may be determined in part by non-technical considerations, such as resistance to materials diversion for military purposes in various scenarios.
  • illustrative nuclear fission igniters may have other types of reactivity sources.
  • other nuclear fission igniters may include "burning embers", e.g., nuclear fission fuel enriched in fissile isotopes via exposure to neutrons within a propagating nuclear fission traveling wave reactor.
  • Such "burning embers” may function as nuclear fission igniters, despite the presence of various amounts of fission products "ash”.
  • nuclear fission igniter modules enriched in fissile isotopes may be used to supplement other neutron sources that use electrically driven sources of high energy ions (such as protons, deuterons, alpha particles, or the like) or electrons that may in turn produce neutrons.
  • a particle accelerator such as a linear accelerator may be positioned to provide high energy protons to an intermediate material that may in turn provide such neutrons (e.g., through spallation).
  • a particle accelerator such as a linear accelerator may be positioned to provide high energy electrons to an intermediate material that may in turn provide such neutrons (e.g., by electro-fission and/or photofission of high-Z elements).
  • a particle accelerator such as a linear accelerator
  • other known neutron emissive processes and structures such as electrically induced fusion approaches, may provide neutrons (e.g., 14 Mev neutrons from D-T fusion) that may thereby be used in addition to nuclear fission igniter modules enriched in fissile isotopes to initiate the propagating fission wave.
  • nuclear fission igniter moderately enriched in fissionable material, such as U or 239 Pu, has a neutron-absorbing material (such as a borohydride or the like) removed from it (such as by operator-commanded electrical heating or by withdrawal of one or more control rods), and the nuclear fission igniter becomes neutronically critical.
  • Local fuel temperature rises to a predetermined temperature and is regulated thereafter, such as by a reactor coolant system and/or a reactivity control system or local thermostating modules (discussed in detail in United States Patent Application No. 11/605,943, entitled AUTOMATED NUCLEAR POWER REACTOR FOR LONG-TERM OPERATION, naming RODERICK A. HYDE, MURIEL Y. ISHIKAWA, NATHAN P. MYHRVOLD, AND LOWELL L. WOOD, JR. as inventors, filed 28 November 2006, the contents of which are hereby incorporated by reference).
  • uranium enrichment of the nuclear fission igniter may be reduced to levels not much greater than that of light water reactor (LWR) fuel by introduction into the nuclear fission igniter and the fuel region immediately surrounding it of a radial density gradient of a refractory moderator, such as graphite.
  • LWR light water reactor
  • High moderator density enables low-enrichment fuel to burn satisfactorily, while decreasing moderator density permits efficient fissile breeding to occur.
  • optimum nuclear fission igniter design may involve trade-offs between proliferation robustness and the minimum latency from initial criticality to the availability of full-rated-power from the fully-ignited fuel- charge of the core.
  • Lower nuclear fission igniter enrichments entail more breeding generations and thus impose longer latencies.
  • the peak reactivity of the reactor core assembly may slowly decrease in the first phase of the nuclear fission ignition process because, although the total fissile isotope inventory is increasing, the total inventory becomes more spatially dispersed.
  • the maximum reactivity may still be slightly positive at the time-point at which its minimum value is attained. Soon thereafter, the maximum reactivity begins to increase rapidly toward its greatest value, corresponding to the fissile isotope inventory in the region of breeding substantially exceeding that remaining in the nuclear fission igniter. For many cases a quasi-spherical annular shell then provides maximum specific power production. At this point, the fuel-charge of the reactor core assembly can be referred to as "ignited.”
  • nuclear fission burning Propagation of the nuclear fission traveling wave, which may also be referred to herein as "nuclear fission burning", will now be discussed.
  • the spherically-diverging shell of maximum specific nuclear power production continues to advance radially from the nuclear fission igniter toward the outer surface of the fuel charge. When it reaches the outer surface, it typically breaks into two spherical zonal surfaces, with each surface propagating in a respective one of two opposite directions along the axis of the cylinder. At this time-point, the full thermal power production potential of the core may have been developed. This interval is characterized as that of the launching period of the two axially-propagating nuclear fission traveling wave burnfronts.
  • the center of the core's fuel- charge is ignited, thus generating two oppositely-propagating waves.
  • This arrangement doubles the mass and volume of the core in which power production occurs at any given time, and thus decreases by two-fold the core's peak specific power generation, thereby quantitatively minimizing thermal transport challenges.
  • the core's fuel charge is ignited at or near one end, as desired for a particular application. Such an approach may result in a single propagating wave in some configurations.
  • the core's fuel charge may be ignited in multiple sites. In yet other embodiments, the core's fuel charge is ignited at any 3-D location within the core as desired for a particular application.
  • two propagating nuclear fission traveling waves may be initiated and propagate away from a nuclear fission ignition site; however, depending upon geometry, nuclear fission fuel composition, the action of neutron modifying control structures, or other considerations, different numbers (e.g., one, three, or more) of nuclear fission traveling waves may be initiated and propagated.
  • the discussion herein refers, without limitation, to propagation of two nuclear fission traveling wave burnfronts.
  • the physics of nuclear power generation is typically effectively time-stationary in the frame of either wave.
  • the speed of wave advance through the fuel is proportional to the local neutron flux, which in turn is linearly dependent on the thermal power drawn from the reactor core assembly via the collective action on the nuclear fission traveling wave's neutron budget of the neutron control system,
  • the neutron control system may be implemented with thermostating modules (not shown) as has been described in United States Patent Application No. 11/605,933, entitled CONTROLLABLE LONG TERM OPERATION OF A NUCLEAR REACTOR, naming RODERICK A. HYDE, MURIEL Y. IS HI RAW A, NATHAN P.
  • the neutron control system may be implemented with one or more rods containing neutron-absorbing material and being movable with one or more control rod drive mechanisms.
  • the temperature of the two ends of the core decreases slightly below the thermostating modules' design set-point, a neutron absorber is thereby withdrawn from the corresponding sub-population of the core's thermostating modules, and the local neutron flux is permitted thereby to increase to bring the local thermal power production to the level which drives the local material temperature up to the set-point of the local thermostating modules.
  • temperature control may be effected by shimming control rods as desired responsive to changes in monitored temperature.
  • this process is not effective in heating the coolant significantly until its two divided flows move into the two nuclear burn- fronts.
  • These two portions of the core's fuel-charge - which are capable of producing significant levels of nuclear power when not suppressed by the neutron absorbers - then act to heat the coolant to the temperature specified by the design set-point of their modules, provided that the nuclear fission fuel temperature does not become excessive (and regardless of the temperature at which the coolant arrived in the core).
  • the two coolant flows then move through the two sections of already-burned fuel centerward of the two burnfronts, removing residual nuclear fission and afterheat thermal power from them, both exiting the fuel-charge at its center. This arrangement encourages the propagation of the two burnfronts toward the two ends of the fuel-charge by ''trimming'' excess neutrons primarily from the trailing edge of each front.
  • the core's neutronics in this configuration may be considered to be substantially self-regulated.
  • the core's nucleonics may be considered to be substantially self-regulating when the fuel density- radius product of the cylindrical core is >200 gm/cm ⁇ (that is, 1-2 mean free paths for neutron-induced fission in a core of typical composition, for a reasonably fast neutron spectrum).
  • One function of the neutron reflector in such core design may be to substantially reduce the fast neutron fluence seen by the outer portions of the reactor, such as its radiation shield, structural supports, outermost shell, and reactivity control system components such as without limitation control rods (when provided) or thermostating modules (when provided).
  • the neutron reflector may also impact the performance of the core by increasing the breeding efficiency and the specific power in the outermost portions of the fuel. Such impact may enhance the reactor's economic efficiency. Outlying portions of the fuel-charge are not used at low overall energetic efficiency, but have isotopic burn-up levels comparable to those at the center of the fuel- charge.
  • While the core's neutronics in the above-described configurations may be considered to be substantially self-regulated, other configurations may operate under control of a reactor control system that includes a suitable electronic controller having appropriate electrical circuitry and that may include a suitable electro-mechanical system, such as one or more rods containing neutron-absorbing material and being movable with one or more control rod drive mechanisms.
  • a reactor control system that includes a suitable electronic controller having appropriate electrical circuitry and that may include a suitable electro-mechanical system, such as one or more rods containing neutron-absorbing material and being movable with one or more control rod drive mechanisms.
  • Final, irreversible negation of the core's neutronic reactivity may be performed at any time by injection of neutronic poison into the coolant stream as desired.
  • lightly loading a coolant stream with a material such as BF3, possibly accompanied by a volatile reducing agent such as H2 if desired may deposit metallic boron substantially uniformly over the inner walls of coolant-tubes threading through the reactor's core, via exponential acceleration of the otherwise slow chemical reaction 2BF3 + 3H2 -> 2B + 6HF by the high temperatures found therein.
  • Boron in turn, is a highly refractory metalloid, and will not typically migrate from its site of deposition. Substantially uniform presence of boron in the core in ⁇ 100 kg quantities may negate the core's neutronic reactivity for indefinitely prolonged intervals without involving the use of powered mechanisms in the vicinity of the reactor.
  • electrical circuitry includes, but is not limited to, electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer configured by a computer program which at least partially carries out processes and/or devices described herein, or a microprocessor configured by a computer program which at least partially carries out processes and/or devices described herein), electrical circuitry forming a memory device (e.g., forms of memory (e.g., random access, flash, read only, etc.)), and/or electrical circuitry forming a communications device (e.g.,
  • electromechanical system includes, but is not limited to, electrical circuitry operably coupled with a transducer (e.g., an actuator, a motor, a piezoelectric crystal, a Micro Electro Mechanical System (MEMS), etc.), electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer configured by a computer program which at least partially carries out processes and/or devices described herein, or a microprocessor configured by a computer program which at least partially carries out processes and/or devices described herein), electrical circuitry forming a memory device (e.g., forms of memory (e.g., random access, flash, read only, etc.)), electrical circuitry forming a communications device (e.g., a modem, communications switch, optical-electrical equipment, etc.), and/or any non-
  • a transducer e.g
  • electro-mechanical systems include but are not limited to a variety of consumer electronics systems, medical devices, as well as other systems such as motorized transport systems, factory automation systems, security systems, and/or communication/computing systems.
  • electro-mechanical as used herein is not necessarily limited to a system that has both electrical and mechanical actuation except as context may dictate otherwise.
  • FIGURE 1 A an illustrative method 10 is provided for operating a nuclear fission traveling wave reactor.
  • FIGURE IB components of an illustrative nuclear fission traveling wave reactor core 12 of a nuclear fission traveling wave reactor are shown by way of example and not of limitation.
  • Nuclear fission fuel subassemblies 14 are housed in a reactor core assembly 16.
  • FIGURE IB may illustrate less than all of the nuclear fission fuel subassemblies 14 that may be housed in embodiments of the reactor core assembly 16.
  • a frame of reference is defined within the reactor core assembly 16.
  • the frame of reference can be defined by an x-dimension, a y-dimension, and a z-dimension.
  • the frame of reference can be defined by a radial dimension and an axial dimension.
  • the frame of reference can include an axial dimension and a lateral dimension.
  • the nuclear fission fuel subassemblies 14 may be individual nuclear fission fuel elements, such as nuclear fission fuel rods, plates, spheres, or the like. In some other embodiments, the nuclear fission fuel subassemblies 14 may be nuclear fission fuel assemblies - that is, two or more individual nuclear fission fuel elements that are grouped into an assembly. Regardless of embodiment of the nuclear fission fuel subassemblies 14, nuclear fission fuel material contained within the nuclear fission fuel subassemblies 14 can be any suitable type of nuclear fission fuel material as described above.
  • the method 10 starts at a block 18.
  • a nuclear fission traveling wave burnfront 22 is propagated (as indicated by arrows 24) along first and second dimensions within the nuclear fission fuel subassemblies 14 in the reactor core assembly 16 of the nuclear fission traveling wave reactor core 12.
  • selected ones of the nuclear fission fuel subassemblies 14 are controllably migrated along the first dimension from respective first locations toward respective second locations in a manner that defines a shape of the nuclear fission traveling wave burnfront 22 along the second dimension according to a selected set of dimensional constraints.
  • the method 10 stops at a block 28.
  • the nuclear fission fuel subassemblies 14 bear a spatial relationship to the dimensions that are designated as the first and second dimensions.
  • the nuclear fission fuel subassemblies 14 may be elongate along the second dimension.
  • the second dimension may be. the y-dimension or an axial dimension.
  • the second dimension may be the x- dimension, the z-dimension, or a lateral dimension.
  • the first dimension may be substantially orthogonal to an elongated axis of the nuclear fission subassemblies 14. In some embodiments, the first dimension and the second dimension may be substantially orthogonal to each other.
  • first dimension and second dimension may be designated as the first dimension and second dimension.
  • first dimension may include a radial dimension and the second dimension may include an axial dimension.
  • first dimension may include an axial dimension and the second dimension may include a radial dimension.
  • first dimension may include an axial dimension and the second dimension may include a lateral dimension.
  • first dimension may include a lateral dimension and the second dimension may include an axial dimension.
  • first dimension may be the radial dimension and the second dimension may be the axial dimension.
  • the fuel assemblies are elongated in a first dimension and can be moved in a lateral or radial second dimension.
  • locations within the reactor core 12 may be characterized as the first locations and the second locations according to various attributes.
  • a location may be considered to be a space in a vicinity of a region of the reactor core 12 around a nuclear fission fuel subassembly 14.
  • a location may also be considered generally to be a space immediately surrounding any given area in the reactor core 12, or may be considered to be most of the reactor core 12.
  • the first locations may include outward locations 30 and the second locations may include inward locations 32.
  • the inward locations 32 and outward locations 30 may be based on geometrical proximity to a central portion of the reactor core 12.
  • the inward locations and the outward locations may be based on neutron flux such that neutron flux at the inward locations is greater than neutron flux at the outward locations. In some other embodiments, the inward locations and the outward locations may be based on reactivity such that keff ec tive at the inward locations is greater than keffective at the outward locations.
  • Embodiments typical of a traveling wave reactor may have outward locations including locations outside, or in the direction of, a propagating wave while inward locations may include locations through which a nuclear fission traveling wave is propagating or has already propagated.
  • the first locations may include the inward locations 32 and the second locations may include the outward locations 30.
  • the inward locations 32 and the outward locations 30 may be based on geometrical proximity to the central portion of the reactor core 12.
  • the inward locations and the outward locations may be based on neutron flux such that neutron flux at the inward locations is greater than neutron flux at the outward locations.
  • the inward locations and the outward locations may be based on reactivity such that keff ect ive at the inward locations is greater than keffective at the outward locations.
  • the inward and outward locations may be described in terms of the predominant nuclear reaction occurring in those regions.
  • the inward location may be characterized by predominantly nuclear fission reactions while the outward location may be characterized by predominantly nuclear absorption reactions on fertile material.
  • the first locations and the second locations may be characterized according to other attributes.
  • the first locations and the second locations may be located on opposite sides of a reference value along the first dimension.
  • the first locations and the second locations may include at least one attribute that is substantially equalized.
  • the at least one attribute that is substantially equalized may include geometrical proximity to a central region of the reactor core, neutron flux, reactivity, or the like.
  • selected ones of the nuclear fission fuel subassemblies may be controllably migrated radially outwardly from respective inward locations 32 toward respective outward locations 30 in a manner that defines a shape of the nuclear fission traveling wave burnfront 22 axially according to a selected set of dimensional constraints.
  • axial changes in shape of the nuclear fission traveling wave burnfront 22 with radial movement of nuclear fission fuel subassemblies are shown.
  • a left pane illustrates an initial shape of the nuclear fission traveling wave burnfront 22. It will be appreciated that, for clarity purposes, only one- fourth of the perimeter of the nuclear fission traveling wave burnfront 22 is shown.
  • a selected nuclear fission fuel subassembly (not shown) has been radially migrated from the inward location 32 to the outward location 30 after the selected nuclear fission fuel subassembly (not shown) has been burned for a desired time or according to a desired reactivity parameter (such as, without limitation, burnup). Reactivity has been moved radially outwardly from a peak that was radially located at the inward location 32 (as shown in the left pane) to the outward location 30 (as shown in the center pane).
  • a desired reactivity parameter such as, without limitation, burnup
  • nuclear fission fuel subassemblies may be radially migrated outwardly from the inward locations 32 to the outward locations 30.
  • nuclear fission fuel subassemblies (not shown) at radially inward locations in the nuclear fission traveling wave reactor core 12 may be kept from burning more than nuclear fission fuel subassemblies (not shown) at radially outward locations in the nuclear fission traveling wave reactor core 12.
  • the shape of the nuclear fission traveling wave burnfront 22 may approximate a Bessel function. Also, if a sufficient number of the nuclear fission fuel subassemblies are migrated radially outwardly as described above, then all or substantially all of the nuclear fission fuel subassemblies in the nuclear fission traveling wave reactor core 12 may reach or approach their respective burn-up limits at around a same time. In such a case, use of the nuclear fission fuel subassemblies in the nuclear fission traveling wave reactor core 12 has been maximized.
  • selected ones of the nuclear fission fuel subassemblies 14 may be controllably migrated radially outwardly from respective inward locations 32 toward respective outward locations 30 and other selected ones of the nuclear fission fuel subassemblies 14' may be controllably migrated radially inwardly from the respective outward locations 30 to the respective inward locations 32 in a manner that defines a shape of the nuclear fission traveling wave burnfront 22 axially according to a selected set of dimensional constraints. That is, the selected nuclear fission fuel assemblies 14 and 14'are interchanged between the inward locations 32 and the outward locations 30.
  • a left pane illustrates an initial shape of the nuclear fission traveling wave burnfront 22.
  • the nuclear fission fuel assemblies 14 have more fissile content than do the nuclear fission fuel assemblies 14'.
  • the nuclear fission fuel subassemblies 14 may be part of an igniter assembly for the nuclear fission traveling wave reactor core 12.
  • the nuclear fission fuel assemblies 14 may include fissile material that has been bred from fertile isotopic material as a result of absorption of fast spectrum neutrons in the nuclear fission traveling wave reactor core 12 and subsequent transmutation into fissile isotopes.
  • the nuclear fission fuel subassemblies 14' have less fissile content than do the nuclear fission fuel subassemblies 14.
  • the nuclear fission fuel subassemblies 14' may include more fertile isotopic content than do the nuclear fission fuel subassemblies 14. In such cases, the nuclear fission fuel subassemblies 14' are more absorptive to fast spectrum neutrons than are the nuclear fission fuel subassemblies 14.
  • the selected nuclear fission fuel subassembly 14 has been radially outwardly migrated from the inward location 32 to the outward location 30 and the selected nuclear fission fuel subassembly 14' has been radially inwardly migrated from the outward location 30 to the inward location 32.
  • the axial profile of the nuclear fission traveling wave burnfront 22 has been made more compact and more uniform compared to the axial profile of the nuclear fission traveling wave burnfront 22 before such interchanging (see the left pane).
  • a substantially uniform profile or uniform profile may be achieved for the nuclear fission traveling wave burnfront 22.
  • nuclear fission traveling wave burnfront 22 it may not be desired to achieve a substantially uniform profile or uniform profile for the nuclear fission traveling wave burnfront 22. In such cases it may merely be desired to relocate fissile material or to relocate fertile isotopic material. In some other embodiments it may be desirable to extend the nuclear fission traveling wave burnfront 22 in the radial dimension.
  • the shape of the nuclear fission traveling wave burnfront 22 also may be defined in the radial dimension by migrating the nuclear fission fuel subassemblies 14 and 14' in the radial dimension as discussed above with reference to FIGURE IF.
  • the radial profile of the nuclear fission traveling wave burnfront 22 may be considered to represent neutron leakage current.
  • the left and right panes of FIGURE 1G show views along the axial dimension that correspond to the left and right panes, respectively, of FIGURE IF.
  • selected ones of the nuclear fission fuel subassemblies 14 may be controllably migrated laterally from respective first locations toward respective second locations in a manner that defines a shape of the nuclear fission traveling wave burnfront 22 radially according to a selected set of dimensional constraints.
  • a left pane illustrates an initial shape of the nuclear fission traveling wave burnfront 22 viewed along the axial dimension.
  • a selected nuclear fission fuel subassembly 14 is located at a first location z, r, In the example shown for illustration purposes, the nuclear fission fuel subassembly 14 contributes reactivity at the first location z, r, ⁇ that may be determined, for any reason whatsoever, to be in excess of an amount of reactivity desired at the first location z, r, ⁇ .
  • the nuclear fission fuel subassembly 14 may be part of an igniter assembly for the nuclear fission traveling wave reactor core 12.
  • the nuclear fission fuel assembly 14 may include fissile material that has been bred from fertile isotopic material as a result of absorption of fast spectrum neutrons in the nuclear fission traveling wave reactor core 12 and subsequent transmutation into fissile isotopes.
  • the nuclear fission traveling wave burnfront 22 may be propagating too much in the radial direction at the first location z, r,
  • the selected nuclear fission fuel subassembly 14 has been laterally migrated along the lateral dimension ⁇ from the first location z, r, q> ⁇ to the second location z, r, ⁇ 2 .
  • the shape of the nuclear fission traveling wave burnfront 22 has been defined radially as a result of lateral migration of the selected nuclear fission fuel subassembly 14 from the first location z, r, q>i to the second location z, r, ⁇ 2 .
  • Controllably migrating selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations at the block 26 may entail one or more processes.
  • controllably migrating selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations at the block 26 may include rotating at least one of the selected ones of the nuclear fission fuel subassemblies 14 at a block 34, as indicated by arrow 36 (FIGURE 1J).
  • rotating at least one of the selected ones of the nuclear fission fuel subassemblies 14 at the block 34 may be performed with any suitable in-core fuel handling system as desired. Furthermore, it may be desired to rotate the selected nuclear fission fuel subassemblies 14 in order to minimize or prevent deformation of reactor structural material, such as bowing of nuclear fission fuel subassemblies.
  • controllably migrating selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations at the block 26 may include inverting at least one of the selected ones of the nuclear fission fuel subassemblies 14 at a block 38, as indicated by arrows 40 (FIGURE 1L). It will be appreciated that inverting at least one of the selected ones of the nuclear fission fuel subassemblies 14 at the block 38 may be performed with any suitable in-core fuel handling system as desired.
  • Inverting a nuclear fission fuel subassembly 14 can result in an inlet of the nuclear fission fuel subassembly 14 (prior to inversion) becoming an outlet of the nuclear fission fuel subassembly 14 (after inversion), and vice versa.
  • Such an inversion can result in axially equalizing thermal stresses and/or radiation effects on the nuclear fission fuel subassembly 14 at the ends of the nuclear fission fuel subassembly 14. Any such radiation effects may be temperature related and/or may be related to variations in neutron flux at the axial ends of the nuclear fission reactor core 12.
  • inversion of a nuclear fission fuel subassembly 14 results in both ends of the inverted nuclear fission fuel subassembly 14 migrating from a first location to a second location about the central point of inversion.
  • any one or more dimensional constraints may be selected as desired for a particular application.
  • the selected set of dimensional constraints may include a predetermined maximum distance along the second dimension.
  • the selected set of dimensional constraints may be a function of at least one burnfront criteria.
  • the burnfront criteria may include neutron flux.
  • the neutron flux may be associated with at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • the burnfront criteria may include neutron fluence.
  • the neutron fluence may be associated with at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • the burnfront criteria may include burnup.
  • the burnup may be associated with at least one of the selected ones of the nuclear fission fuel subassemblies 14. In such arrangements, it may be desirable to move the selected ones of the nuclear fission fuel subassemblies 14 from a first location having a first burn-up rate to a second location having a second burn-up rate.
  • the first location may be a location that is characterized by a high burn-up rate and the second location may be a location that is characterized by a reduced burn-up rate (relative to the high burn-up rate at the first location) or a substantially zero value of burn-up rate.
  • the burnfront criteria may include burnfront location within at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • Burnfront location may be characterized by features of the nuclear fission traveling wave reactor core 12 or nuclear fission fuel subassemblies 14 therein. Such features may include, but are not limited to, fission rate, breeding rate, power output, temperature, reactivity, and the like.
  • controllably migrating selected ones of the nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations at the block 26 may be performed in any manner as desired for a particular application.
  • controllably migrating selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations at the block 26 may include controllably migrating selected ones of the nuclear fission fuel subassemblies 14 radially along the first dimension from respective first locations toward respective second locations at a block 42.
  • radial migration at the block 42 may be performed with any suitable in-core fuel handling system as desired.
  • controllably migrating selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations at the block 26 may include controllably migrating selected ones of the nuclear fission fuel subassemblies spirally along the first dimension from respective first locations toward respective second locations at a block 44, as indicated by arrow 46. It will be appreciated that spiral migration at the block 44 may be performed with any suitable in-core fuel handling system as desired.
  • controllably migrating selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations at the block 26 may include controllably migrating selected ones of the nuclear fission fuel subassemblies 14 axially along the first dimension from respective first locations toward respective second locations at a block 48, as indicated by an arrow 50. It will be appreciated that axial migration at the block 48 may be performed with any suitable in- core fuel handling system as desired.
  • the shape of the nuclear fission traveling wave bumfront 22 may be defined by any parameter associated with the nuclear fission traveling wave burnfront 22, such as without limitation neutron flux, neutron fluence, burnup, and/or reactivity (or any of their components). It will also be appreciated that the nuclear fission traveling wave burnfront 22 may have any shape as desired for a particular application. For example and referring additionally to FIGURE 1R, in some embodiments the shape of the nuclear fission traveling wave burnfront 22 may be substantially spherical. In some other embodiments and referring additionally to FIGURE IS, the shape of the nuclear fission traveling wave burnfront 22 may substantially conform to a selected continuously curved surface.
  • the shape of the nuclear fission traveling wave burnfront 22 may be substantially rotationally symmetrical around the second dimension. In some other embodiments and referring additionally to FIGURES 1U and IV, the shape of the nuclear fission traveling wave burnfront 22 may have substantial n-fold rotational symmetry around the second dimension.
  • migrating nuclear fission fuel subassemblies as described above may act to supply either fertile isotopic material or fissile material to the reaction zone.
  • Moving nuclear fission fuel subassemblies radially outward may serve to migrate nuclear fission fuel subassemblies having reached their burn-up limit out of an area of high neutronic activity.
  • Radially outward movement may also serve to lower the power density of the burning region by spreading fissile, burnable, nuclear fission fuel material to previously non-burning regions.
  • nuclear fission fuel subassemblies may be exchanged (or interchanged) with nuclear fission fuel subassemblies in other locations.
  • fertile isotopic material may be exchanged from a fertile blanket region with well-burned material from the reactor burning region.
  • nuclear fission fuel material may be exchanged from directly-adjacent reactor core locations such that two or more nuclear fission fuel subassemblies trade locations.
  • the shape of the nuclear fission traveling wave burnfront 22 along the second dimension may be asymmetrical. In some arrangements, the shape of the nuclear fission traveling wave burnfront 22 may be rotationally asymmetrical around the second dimension.
  • the method 20 may also include initiating the nuclear fission traveling wave burnfront 22 with nuclear fission traveling wave igniter assemblies (not shown) at a block 52. Illustrative examples of initiation of a nuclear fission traveling wave with nuclear fission traveling wave igniter assemblies have been discussed above and need not be repeated.
  • at a block 54 at least one of the nuclear fission traveling wave igniter assemblies may be removed prior to controllably migrating selected ones of the nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations.
  • removing at least one of the nuclear fission traveling wave igniter assemblies at the block 54 prior to controllably migrating selected ones of the nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations may include, at a block 56, removing at least one of the nuclear fission traveling wave igniter assemblies from the second locations prior to controllably migrating selected ones of the nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations.
  • the nuclear fission traveling wave reactor is caused to become subcritical prior to controllably migrating selected ones of the nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations.
  • causing the nuclear fission traveling wave reactor to become subcritical at the block 58 may include inserting neutron absorbing material into the reactor core at a block 60.
  • criticality may be re-established after controUably migrating selected ones of the nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations.
  • re-establishing criticality at the block 62 may include removing at least a portion of neutron absorbing material from the reactor core at a block 64.
  • the nuclear fission traveling wave reactor may be shut down prior to controUably migrating selected ones of the nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations.
  • the nuclear fission traveling wave reactor may be re-started after controUably migrating selected ones of the nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations.
  • an illustrative method 200 for controlling a nuclear fission traveling wave reactor in which a nuclear fission traveling wave burnfront 22 is propagating along first and second dimensions.
  • the method 200 starts at a block 202.
  • a desired shape of the nuclear fission traveling wave burnfront 22 is determined along the second dimension within the nuclear fission fuel subassemblies 14 according to a selected set of dimensional constraints.
  • a migration of selected ones of the nuclear fission fuel subassemblies 14 is determined along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape.
  • an existing shape of the nuclear fission traveling wave burnfront 22 is determined. It will be appreciated that determining the existing shape of the nuclear fission traveling wave burnfront 22 at the block 210 may be performed as desired in relation to determining the desired shape of the nuclear fission traveling wave burnfront 22 at the block 204. In some embodiments determining the existing shape of the nuclear fission traveling wave bumfront 22 at the block 210 may be performed prior to determining the desired shape of the nuclear fission traveling wave bumfront 22 at the block 204.
  • determining the existing shape of the nuclear fission traveling wave bumfront 22 at the block 210 may be performed substantially simultaneously with determining the desired shape of the nuclear fission traveling wave bumfront 22 at the block 204. In some other embodiments determining the existing shape of the nuclear fission traveling wave bumfront 22 at the block 210 may be performed after determining the desired shape of the nuclear fission traveling wave bumfront 22 at the block 204.
  • the desired shape may be determined as desired, including determination of fission rate, estimated bum-up, breeding rate, temperature distribution, power distribution, assembly operational history, and reactivity worth of the migrated nuclear fission fuel material within respective locations.
  • the selected ones of the nuclear fission fuel subassemblies 14 may be migrated for any purpose as desired for a particular application, such as establishing the desired shape of the nuclear fission traveling wave bumfront 22 and/or maintaining the desired shape of the nuclear fission traveling wave bumfront 22.
  • determining a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape at the block 206 may include determining a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner to establish the desired shape at a block 212.
  • determining a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape may include determining a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner to maintain the desired shape at a block 214. It will be appreciated that it may be desirable to determine, among other things, a time when to perform desired migration.
  • the selected ones of the nuclear fission fuel subassemblies 14 may be migrated. Referring additionally to FIGURE 2F, at a block 218 the selected ones of the nuclear fission fuel subassemblies 14 may be migrated along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape.
  • the nuclear fission fuel subassemblies 14 may be elongate along the second dimension.
  • the first dimension may be substantially orthogonal to an elongated axis of the nuclear fission subassemblies 14.
  • the first dimension and the second dimension may be substantially orthogonal to each other.
  • the first dimension may include a radial dimension and the second dimension may include an axial dimension.
  • the first dimension may include an axial dimension and the second dimension may include a radial dimension.
  • Nuclear fission reactors of any type may include nuclear fission fuel subassemblies that extend across the entire axial dimension with multiple nuclear fission fuel subassemblies extending across the radial dimension.
  • a nuclear fission traveling wave may propagate along and axial dimension at a different rate than in the radial dimension depending on the power distribution and the divergence, in this case, of the nuclear fission traveling wave from inner regions to outer regions, particularly in cylindrical reactor core configurations.
  • Nuclear fission fuel subassemblies with a burnfront that is expanding to undesired axial locations may be moved radially such that the nuclear fission fuel subassemblies are subjected to neutronic activity at locations within the nuclear fission fuel subassembly which reduce or limit further burnfront propagation to undesired locations.
  • the burn-front may be made non-uniform in the radial dimension through controlled migration of nuclear fission fuel subassemblies such that, if desired, alternating zones of varying enrichment can be created. Placing high enrichment zones next to depleted or low enrichment zones increases neutron leakage from the high enrichment zone to the low enrichment zone, thereby facilitating conversion of the fertile isotopic material to fissile material. It will be appreciated that the above migrations may be performed to promote propagation in a first dimension while limiting propagation in a second dimension.
  • the first dimension may include an axial dimension and the second dimension may include a lateral dimension.
  • the first dimension may include a lateral dimension and the second dimension may include an axial dimension.
  • the first locations may include the outward locations 30 and the second locations may include the inward locations 32.
  • the inward locations 32 and the outward locations 30 may be based on geometrical proximity to a central portion of the reactor core 12.
  • the inward locations 32 and the outward locations 30 may also be based on neutron flux such that neutron flux at the inward locations 32 is greater than neutron flux at the outward locations 30.
  • the inward locations 32 and the outward locations 30 may be based on reactivity such that keffective at the inward locations 32 is greater than keffective at the outward locations 30.
  • the first locations may include the inward locations 32 and the second locations may include the outward locations 30.
  • the inward locations and the outward locations may be based on geometrical proximity to a central portion of the reactor core 12, and/or based on neutron flux such that neutron flux at the inward locations is greater than neutron flux at the outward locations, and/or based on reactivity such that keffective at the inward locations is greater than keffective at the outward locations.
  • the first locations and the second locations may be located on opposite sides of a reference value along the first dimension.
  • the first locations and the second locations may include at least one attribute that is substantially equalized.
  • the at least one attribute may include geometrical proximity to a central region of the reactor core 12, neutron flux, and/or reactivity.
  • determining a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations at the block 206 may include determining a rotation of at least one of the selected ones of the nuclear fission fuel subassemblies 14 at a block 220. In some embodiments and referring additionally to FIGURE 2H, determining a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations at the block 206 may include determining an inversion of at least one of the selected ones of the nuclear fission fuel subassemblies 14 at a block 222.
  • the selected set of dimensional constraints may include a predetermined maximum distance along the second dimension.
  • the selected set of dimensional constraints is a function of at least one bumfront criteria.
  • the bumfront criteria may include neutron flux, such as without limitation neutron flux that is associated with at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • the burnfront criteria may include neutron fluence, such as without limitation neutron fluence that is associated with at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • the burnfront criteria may include burnup, such as without limitation burnup that is associated with at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • the burnfront criteria may include burnfront location within at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • determining a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations at the block 206 may include determining a radial migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations at a block 224.
  • determining a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations at the block 206 may include determining a spiral migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations at a block 226.
  • determining a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations at the block 206 may include determining an axial translation of selected ones of the nuclear fission fuel subassemblies 14 at a block 228.
  • determining a desired shape of the nuclear fission traveling wave burnfront 22 at the block 204 may include determining a substantially spherical shape of the nuclear fission traveling wave burnfront 22 at a block 230.
  • determining a desired shape of the nuclear fission traveling wave burnfront 22 along the second dimension at the block 204 may include determining a continuously curved surface shape of the nuclear fission traveling wave burnfront 22 at a block 232.
  • the curved surface may be made such that the surface area of the burnfront is enhanced. In such embodiments, leakage of neutrons from burning zones to breeding zones is enhanced.
  • the desired shape of the nuclear fission traveling wave burnfront 22 may be any shape. As discussed above, in various embodiments the desired shape of the nuclear fission traveling wave burnfront 22 may be substantially rotationally symmetrical around the second dimension; the desired shape of the nuclear fission traveling wave burnfront 22 may have substantial n-fold rotational symmetry around the second dimension; the desired shape of the nuclear fission traveling wave burnfront 22 may be asymmetrical; and/or the desired shape of the nuclear fission traveling wave burnfront 22 may be rotationally asymmetrical around the second dimension. In some other embodiments symmetrical shapes of n-fold symmetry may be transformed into separate burning zones within the nuclear fission traveling wave reactor core. For example, the burnfront can be transformed into lobes that can further be propagated into n- or less separate (that is, neutronically decoupled) burning regions (see FIGURE IV).
  • an illustrative system 300 is provided for determining migration of nuclear fission fuel subassemblies (not shown in FIGURE 3A).
  • the system 300 may provide a suitable system environment for performance of the method 200 (FIGURES 2A-2M).
  • electrical circuitry 302 is configured to determine a desired shape of the nuclear fission traveling wave burnfront 22 along the second dimension within the nuclear fission fuel subassemblies 14 according to a selected set of dimensional constraints.
  • Electrical circuitry 304 is configured to determine a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape.
  • electrical circuitry includes, but is not limited to, electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer configured by a computer program which at least partially carries out processes and/or devices described herein, or a microprocessor configured by a computer program which at least partially carries out processes and/or devices described herein), electrical circuitry forming a memory device (e.g., forms of memory (e.g., random access, flash, read only, etc.)), and/or electrical circuitry forming a communications device (e.g.,
  • the electrical circuitry 302 and/or the electrical circuitry 304 may be embodied as a computing system 306 (that also may be referred to as a host computer or system).
  • a central processing unit (“CPU") (or microprocessor) 308 is connected to a system bus 310.
  • Random access main memory (“RAM”) 312 is coupled to the system bus 310 and provides the CPU 308 with access to memory storage 314 (which may be used for storage of data associated with one or more parameters of the nuclear fission traveling wave burnfront 22).
  • RAM random access main memory
  • the CPU 308 stores those process steps in the RAM 312 and executes the stored process steps out of the RAM 312.
  • the computing system 306 may connect to a computer network (not shown) via a network interface 316 and through a network connection (not shown).
  • a computer network not shown
  • One such network is the Internet that allows the computing system 306 to download applications, code, documents and other electronic information.
  • ROM 318 is provided to store invariant instruction sequences such as start-up instruction sequences or basic input/output operating system (BIOS) sequences.
  • An Input/Output (“I/O") device interface 320 allows the computing system 306 to connect to various input/output devices, for example, a keyboard, a pointing device ("mouse”), a monitor, printer, a modem, and the like.
  • the I/O device interface 320 is shown as a single block for simplicity and may include several interfaces to interface with different types of I/O devices.
  • the computing system 306 may have more or fewer components.
  • the computing system 306 can be a set-top box, a lap-top computer, a notebook computer, a desktop system, or other types of systems.
  • portions of disclosed systems and methods include one or more computer program products.
  • the computer program product includes a computer-readable storage medium, such as the non-volatile storage medium, and computer-readable program code portions, such as a series of computer instructions, embodied in the computer-readable storage medium.
  • the computer program is stored and executed by a processing unit or a related memory device, such as the processing components depicted in FIGURE 3B.
  • FIGURES 2A-2M and 3A-3C are flowcharts and block diagrams, respectively, of methods, systems, and program products according to various embodiments. It will be understood that each block of the flowcharts and block diagrams, and combinations of blocks in the flowcharts and block diagrams, can be implemented by computer program instructions. These computer program instructions may be loaded onto a computer or other programmable apparatus to produce a machine, such that the instructions which execute on the computer or other programmable apparatus create means for implementing the functions specified in the flowchart(s) or block diagram(s).
  • These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart(s) or block diagram(s).
  • the computer program instructions may also be loaded onto a computer or other programmable apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart(s) or block diagram(s).
  • blocks of the flowchart or block diagram support combinations of means for performing the specified functions, combinations of steps for performing the specified functions, and program instruction means for performing the specified functions. It will also be understood that each block of the flowchart or block diagram and combinations of blocks in the flowchart(s) or block diagram(s) can be implemented by special purpose hardware-based computer systems which perform the specified functions or steps, or combinations of special purpose hardware and computer instructions.
  • the electrical circuitry 304 may be further configured to determine an existing shape of the nuclear fission traveling wave burnfront 22.
  • sensors 322 may be operatively coupled to the electrical circuitry 304 in signal communication via a suitable input interface 324.
  • the sensors 322 may include any suitable sensor that measures a parameter of the nuclear fission traveling wave burnfront 22.
  • the sensors 322 may measure neutron flux, neutron fluence, burnup, and/or reactivity (or any of their components).
  • embodiments of the system 300 and the electrical circuitry 302 and 304 may be configured to provide a suitable system environment for performance of the method 200 (FIGURES 2A-2M) regardless of whether computer program instructions are loaded onto a computer or other programmable apparatus to produce a machine such that the instructions which execute on the computer or other programmable apparatus create means for implementing the functions specified in the flowchart(s) or block diagram(s) or each block of the flowchart or block diagram and combinations of blocks in the flowchart(s) or block diagram(s) are implemented by special purpose hardware-based computer systems which perform the specified functions or steps, or combinations of special purpose hardware and computer instructions.
  • FIGURES 1B-D, 1J, 1L, 10, 1Q, 1R-1W, and 2A-2M Some features of embodiments of the system 300 will be discussed with reference additionally to FIGURES 1B-D, 1J, 1L, 10, 1Q, 1R-1W, and 2A-2M.
  • the electrical circuitry 304 may be further configured to determine a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner to establish the desired shape.
  • the electrical circuitry 304 may be further configured to determine a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner to maintain the desired shape.
  • the electrical circuitry 304 may be further configured to determine a time when to migrate the selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape.
  • the nuclear fission fuel subassemblies 14 may be elongate along the second dimension.
  • the first dimension may be substantially orthogonal to an elongated axis of the nuclear fission subassemblies 14. In some other embodiments, the first dimension and the second dimension may be substantially orthogonal to each other.
  • the first dimension may include a radial dimension and the second dimension may include an axial dimension; the first dimension may include an axial dimension and the second dimension may include a radial dimension; the first dimension may include an axial dimension and the second dimension may include a lateral dimension; and/or the first dimension may include a lateral dimension and the second dimension may include an axial dimension 1 .
  • the first locations may include the outward locations 30 and the second locations may include the inward locations 32.
  • the inward locations 32 and the outward locations 30 may be based on various attributes as desired, such as without limitation geometrical proximity to a central portion of the reactor core 12, neutron flux such that neutron flux at the inward locations 32 is greater than neutron flux at the outward locations 30, and/or reactivity such that keffective at the inward locations 32 is greater than keffective at the outward locations 30.
  • the first locations may include the inward locations 32 and the second locations may include the outward locations 30.
  • the inward locations 32 and the outward locations 30 may be based on various attributes as desired, such as without limitation geometrical proximity to a central portion of the reactor core 12, neutron flux such that neutron flux at the inward locations 32 is greater than neutron flux at the outward locations 30, and/or reactivity such that keffective at the inward locations 32 is greater than keffective at the outward locations 30.
  • the first locations and the second locations may be located on opposite sides of a reference value along the first dimension.
  • the first locations and the second locations may include at least one attribute that is substantially equalized.
  • the at least one attribute may include geometrical proximity to a central region of the reactor core 12, neutron flux, and/or reactivity.
  • the electrical circuitry 304 may be further configured to determine rotation of at least one of the selected ones of the nuclear fission fuel subassemblies 14. In some other embodiments the electrical circuitry 304 may be further configured to determine inversion of at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • the selected set of dimensional constraints may include a predetermined maximum distance along the second dimension.
  • the selected set of dimensional constraints may be a function of at least one bumfront criteria.
  • the bumfront criteria may include without limitation: neutron flux, such as neutron flux that is associated with at least one of the selected ones of the nuclear fission fuel subassemblies 14; neutron fluence, such as neutron fluence that is associated with at least one of the selected ones of the nuclear fission fuel subassemblies 14; and/or burnup, such as bumup that is associated with at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • the bumfront criteria may include bumfront location within at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • the electrical circuitry 304 may be further configured to determine a radial migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations.
  • the electrical circuitry 304 may be further configured to determine a spiral migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations.
  • the electrical circuitry 304 may be further configured to determine an axial translation of selected ones of the nuclear fission fuel subassemblies 14.
  • the electrical circuitry 302 may be further configured to determine a substantially spherical shape of the nuclear fission traveling wave burnfront 22.
  • the electrical circuitry 302 may be further configured to determine a continuously curved surface shape of the nuclear fission traveling wave burnfront 22.
  • the desired shape of the nuclear fission traveling wave burnfront 22 may be substantially rotationally symmetrical around the second dimension; may have substantial n-fold rotational symmetry around the second dimension; and/or may be asymmetrical, such as without limitation by being rotationally asymmetrical around the second dimension.
  • FIGURE 4A another illustrative system 400 is provided for migrating nuclear fission fuel subassemblies (not shown in FIGURE 3A).
  • the system 400 may provide a suitable system environment for performance of the method 100 (FIGURES 1A-1AF). As such, the following discussion is made with additional reference to FIGURES 1A-1AF.
  • electrical circuitry 402 is configured to determine a desired shape of the nuclear fission traveling wave burnfront 22 along the second dimension within the nuclear fission fuel subassemblies 14 according to a selected set of dimensional constraints.
  • Electrical circuitry 404 is configured to determine a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape.
  • a subassembly 405 is configured to migrate selected ones of the nuclear fission fuel subassemblies 14 responsive to the electrical circuitry 404.
  • the electrical circuitry 402 and 404 may be similar to the electrical circuitry 302 and 304. In some cases, the electrical circuitry 402 and 404 may be the same as the electrical circuitry 302 and 304. To that end and for sake of brevity, details need not be repeated for an understanding.
  • the electrical circuitry 402 and/or the electrical circuitry 404 may be embodied as a computing system 406 (that also may be referred to as a host computer or system).
  • a central processing unit (“CPU") (or microprocessor) 408 is connected to a system bus 410.
  • Random access main memory (“RAM”) 412 is coupled to the system bus 410 and provides the CPU 408 with access to memory storage 414 (which may be used for storage of data associated with one or more parameters of the nuclear fission traveling wave burnfront 22).
  • RAM random access main memory
  • the CPU 408 stores those process steps in the RAM 412 and executes the stored process steps out of the RAM 412.
  • the computing system 406 may connect to a computer network (not shown) via a network interface 416 and through a network connection (not shown).
  • Read only memory (“ROM”) 418 is provided to store invariant instruction sequences such as start-up instruction sequences or basic input/output operating system (BIOS) sequences.
  • An Input/Output (“I/O") device interface 420 allows the computing system 406 to connect to various input/output devices, for example, a keyboard, a pointing device ("mouse”), a monitor, printer, a modem, and the like. It will be appreciated that embodiments are not limited to the architecture of the computing system 406 shown in FIGURE 4B. The discussion of non-limitation regarding the computing system 306 (FIGURE 3B) also applies to the computing system 406.
  • portions of disclosed systems and methods include one or more computer program products.
  • the discussion above regarding computer program products related to the system 300 (FIGURE 3A) also applies to the system 400.
  • FIGURES 1A, II, IK, 1M-1N, IP, and 1X-1AF and 4A-4C are flowcharts and block diagrams, respectively, of methods, systems, and program products according to various embodiments. It will be understood that each block of the flowcharts and block diagrams, and combinations of blocks in the flowcharts and block diagrams, can be implemented by computer program instructions. These computer program instructions may be loaded onto a computer or other programmable apparatus to produce a machine, such that the instructions which execute on the computer or other programmable apparatus create means for implementing the functions specified in the flowchart(s) or block diagram(s).
  • These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart(s) or block diagram(s).
  • the computer program instructions may also be loaded onto a computer or other programmable apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart(s) or block diagram(s).
  • blocks of the flowchart or block diagram support combinations of means for performing the specified functions, combinations of steps for performing the specified functions, and program instruction means for performing the specified functions. It will also be understood that each block of the flowchart or block diagram and combinations of blocks in the flowchart(s) or block diagram(s) can be implemented by special purpose hardware-based computer systems which perform the specified functions or steps, or combinations of special purpose hardware and computer instructions.
  • the electrical circuitry 404 may be further configured to determine an existing shape of the nuclear fission traveling wave burnfront 22.
  • sensors 422 may be operatively coupled to the electrical circuitry 404 in signal communication via a suitable input interface 424.
  • the electrical circuitry 404, sensors 422, and input interface 424 may be similar to (and in some cases may be the same as) the electrical circuitry 304, sensors 322, and input interface 324 (all FIGURE 3C). Repetition of their details is not necessary for an understanding.
  • embodiments of the system 400, the electrical circuitry 402 and 404, and the subassembly 405 may be configured to provide a suitable system environment for performance of the method 100 (FIGURES 1 A, II, IK, 1M-1N, IP, and 1X-1AF) regardless of whether computer program instructions are loaded onto a computer or other programmable apparatus to produce a machine such that the instructions which execute on the computer or other programmable apparatus create means for implementing the functions specified in the flowchart(s) or block diagram(s) or each block of the flowchart or block diagram and combinations of blocks in the flowchart(s) or block diagram(s) are implemented by special purpose hardware-based computer systems which perform the specified functions or steps, or combinations of special purpose hardware and computer instructions.
  • the electrical circuitry 404 may be further configured to determine an existing shape of the nuclear fission traveling wave bumfront 22. Such a determination may be made in a similar or same manner by the electrical circuitry 304 (FIGURE 3A) as described above. To that end, sensors 422 and an input interface 424 are similar or, in some cases, the same as the sensors 322 and the input interface 324 (all FIGURE 3C). The sensors 422, input interface 424, and electrical circuitry 404 cooperate as discussed above for the sensors 322, input interface 324, and electrical circuitry 304 (all FIGURE 3C).
  • the electrical circuitry 404 may be further configured to determine a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner to establish the desired shape. In some other embodiments, the electrical circuitry 404 may be further configured to determine a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner to maintain the desired shape.
  • the electrical circuitry 404 may be further configured to determine a time when to migrate the selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape.
  • the nuclear fission fuel subassemblies 14 may be elongate along the second dimension.
  • the first dimension may be substantially orthogonal to an elongated axis of the nuclear fission subassemblies 14.
  • the first dimension and the second dimension may be substantially orthogonal to each other.
  • the first dimension may include a radial dimension and the second dimension may includes an axial dimension; the first dimension may include an axial dimension and the second dimension may include a radial dimension; the first dimension may include an axial dimension and the second dimension may include a lateral dimension; and/or the first dimension may include a lateral dimension and the second dimension may include an axial dimension.
  • the first locations may include the outward locations 30 and the second locations may include the inward locations 32.
  • the inward locations 32 and the outward locations 30 may be based on: geometrical proximity to a central portion of the reactor core 12; neutron flux such that neutron flux at the inward locations 32 is greater than neutron flux at the outward locations 30; and/or reactivity such that Ineffective at the inward locations 32 is greater than keff ec tive at the outward locations 30.
  • the first locations may include the inward locations 32 and the second locations include the outward locations 30.
  • the inward locations and outward locations may be based on geometrical proximity to a central portion of the reactor core 12; neutron flux such that neutron flux at the inward locations 32 is greater than neutron flux at the outward locations 30; and/or reactivity such that keff ect ive at the inward locations 32 is greater than keff ec tive at the outward locations 30.
  • first locations and the second locations may be located on opposite sides of a reference value along the first dimension.
  • the first locations and the second locations may include at least one attribute that is substantially equalized.
  • the at least one attribute may include geometrical proximity to a central region of the reactor core 12; neutron flux; and/or reactivity.
  • the electrical circuitry 404 may be further configured to determine rotation of at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • the electrical circuitry 404 may be further configured to determine inversion of at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • the subassembly 405 may include any suitable nuclear fuel handling apparatus known in the art, such as without limitation an in-core nuclear fuel handling apparatus. However, in some other embodiments the subassembly 405 may include an extra-core fuel handling apparatus.
  • the subassembly 405 may be further configured to radially migrate selected ones of the nuclear fission fuel subassemblies 14 from respective first locations toward respective second locations.
  • the subassembly 405 may be further configured to spirally migrate selected ones of the nuclear fission fuel subassemblies 14 from respective first locations toward respective second locations.
  • the subassembly 405 may be further configured to axially translate selected ones of the nuclear fission fuel subassemblies.
  • the subassembly 405 may be further configured to rotate selected ones of the nuclear fission fuel subassemblies 14. In some other embodiments the subassembly 405 may be further configured to invert selected ones of the nuclear fission fuel subassemblies 14.
  • FIGURE 5 in various embodiments an illustrative nuclear fission traveling wave reactor 500 may be provided.
  • the nuclear fission traveling wave reactor 500 includes the nuclear fission traveling wave reactor core 12. As discussed above, the nuclear fission fuel subassemblies 14 are received in the nuclear fission traveling wave reactor core 12. Each of the nuclear fission fuel subassemblies 12 are configured to propagate the nuclear fission traveling wave burnfront 22 therein along first and second dimensions.
  • the electrical circuitry 402 is configured to determine a desired shape of the nuclear fission traveling wave burnfront 22 along the second dimension within the nuclear fission fuel subassemblies 14 according to a selected set of dimensional constraints.
  • the electrical circuitry 404 is configured to determine a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape.
  • the subassembly 405 is configured to migrate selected ones of the nuclear fission fuel subassemblies 14 responsive to the electrical circuitry 404.
  • the reactor 500 may be embodied as the reactor core 12, discussed above, in combination with and cooperating with the system 400, also discussed above. Because details have been set forth above regarding the reactor core 12 (and its components) and the system 400 (and its components), details need not be repeated for an understanding.
  • the electrical circuitry 404 may be further configured to determine an existing shape of the nuclear fission traveling wave burnfront 22.
  • the electrical circuitry 404 may be further configured to determine a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner to establish the desired shape.
  • the electrical circuitry 404 may be further configured to determine a migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner to maintain the desired shape.
  • the electrical circuitry 404 may be further configured to determine a time when to migrate the selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape.
  • the nuclear fission fuel subassemblies 14 may be elongate along the second dimension.
  • the first dimension may be substantially orthogonal to an elongated axis of the nuclear fission subassemblies 14. In some embodiments the first dimension and the second dimension may be substantially orthogonal to each other.
  • the first dimension may include a radial dimension and the second dimension may include an axial dimension; the first dimension may include an axial dimension and the second dimension may include a radial dimension; the first dimension may include an axial dimension and the second dimension may include a lateral dimension; and/or the first dimension may include a lateral dimension and the second dimension may include an axial dimension.
  • the first locations may include the outward locations 30 and the second locations include the inward locations 32.
  • the inward locations 32 and the outward locations 30 may be based on geometrical proximity to a central portion of the reactor core 12; neutron flux such that neutron flux at the inward locations 32 is greater than neutron flux at the outward locations 30; and/or reactivity such that keff ec tive at the inward locations 32 is greater than keffective at the outward locations 30.
  • the first locations may include the inward locations 32 and the second locations may include the outward locations 30.
  • the inward locations 32 and the outward locations 30 may be based on geometrical proximity to a central portion of the reactor core 12; neutron flux such that neutron flux at the inward locations 32 is greater than neutron flux at the outward locations 30; and/or reactivity such that keffective at the inward locations 32 is greater than keffective at the outward locations 30.
  • first locations and the second locations may be located on opposite sides of a reference value along the first dimension.
  • the first locations and the second locations may include at least one attribute that is substantially equalized.
  • the at least one attribute may include geometrical proximity to a central region of the reactor core 12; neutron flux; and/or reactivity.
  • the electrical circuitry 404 may be further configured to determine rotation of at least one of the selected ones of the nuclear fission fuel subassemblies 14 and/or further configured to determine inversion of at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • the selected set of dimensional constraints may include a predetermined maximum distance along the second dimension.
  • the selected set of dimensional constraints may be a function of at least one burnfront criteria, such as without limitation: neutron flux, such as neutron flux that is associated with at least one of the selected ones of the nuclear fission fuel subassemblies 14; neutron fluence, such as neutron fluence that is associated with at least one of the selected ones of the nuclear fission fuel subassemblies 14; and/or burnup, such as burnup that is associated with at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • the burnfront criteria may include bumfront location within at least one of the selected ones of the nuclear fission fuel subassemblies 14.
  • the electrical circuitry 404 may be further configured to determine a radial migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations.
  • the electrical circuitry 404 may be further configured to determine a spiral migration of selected ones of the nuclear fission fuel subassemblies 14 along the first dimension from respective first locations toward respective second locations.
  • the electrical circuitry 404 may be further configured to determine an axial translation of selected ones of the nuclear fission fuel subassemblies 14.
  • the electrical circuitry 402 may be further configured to determine a substantially spherical shape of the nuclear fission traveling wave bumfront 22 and/or a continuously curved surface shape of the nuclear fission traveling wave bumfront 22.
  • the desired shape of the nuclear fission traveling wave bumfront 22 may be substantially rotationally symmetrical around the second dimension; may have substantial n-fold rotational symmetry around the second dimension; and/or may be asymmetrical, such as rotationally asymmetrical around the second dimension.
  • the subassembly 405 may include a nuclear fuel handling apparatus.
  • the subassembly 405 may include any suitable nuclear fuel handling apparatus known in the art, such as without limitation an in-core nuclear fuel handling apparatus.
  • the subassembly 405 may include an extra-core fuel handling apparatus.
  • the subassembly 405 may be further configured to radially migrate selected ones of the nuclear fission fuel subassemblies 14 from respective first locations toward respective second locations.
  • the subassembly 405 may be further configured to spirally migrate selected ones of the nuclear fission fuel subassemblies 14 from respective first locations toward respective second locations.
  • the subassembly 405 may be further configured to axially translate selected ones of the nuclear fission fuel subassemblies 14.
  • the subassembly 405 may be further configured to rotate selected ones of the nuclear fission fuel subassemblies 14.
  • the subassembly 405 may be further configured to invert selected ones of the nuclear fission fuel subassemblies 14.
  • a method 600 for operating a nuclear fission traveling wave reactor.
  • the method 600 starts at a block 602.
  • at a block 604 at least one nuclear fission fuel assembly 14 is migrated outwardly from a first location in the nuclear fission traveling wave reactor core 12 to a second location in the nuclear fission traveling wave reactor core 12.
  • the method 600 stops at a block 606.
  • the at least one nuclear fission fuel assembly 14 may be migrated inwardly from the second location.
  • the first locations and the second locations may be based on geometrical proximity to a central portion of the reactor core 12; neutron flux such that neutron flux at the first locations is greater than neutron flux at the second locations; and reactivity such that kef&ctive at the first locations is greater than keffective at the second locations.
  • a method 700 for operating a nuclear fission traveling wave reactor.
  • the method 700 starts at a block 702.
  • a migration is determined of at least one nuclear fission fuel assembly 14 in a first direction from a first location in a nuclear fission traveling wave reactor core 12 to a second location in the nuclear fission traveling wave reactor core 12.
  • the second location is different from the first location.
  • a migration is determined of the at least one nuclear fission fuel assembly 14 in a second direction from the second location.
  • the second direction is different from the first direction.
  • the method 700 stops at a block 708.
  • the first direction may be outwardly and the second direction may be inwardly.
  • the first locations and the second locations may be based various attributes or parameters, such as without limitation: geometrical proximity to a central portion of the reactor core 12; neutron flux such that neutron flux at the first locations is greater than neutron flux at the second locations; and/or reactivity such that keffective at the first locations is greater than keff ect ive at the second locations.
  • the first direction may be inwardly and the second direction may be outwardly.
  • the second locations and the first locations may be based on various attributes or parameters,' such as without limitation: geometrical proximity to a central portion of the reactor core 12; neutron flux such that neutron flux at the second locations is greater than neutron flux at the first locations; and/or reactivity such that Ineffective at the second locations is greater than keffective at the first locations.
  • a method 800 for operating a nuclear fission traveling wave reactor.
  • the method 800 starts at a block 802.
  • at a block 804 at least one nuclear fission fuel assembly 14 is migrated in a first direction from a first location in the nuclear fission traveling wave reactor core 12 to a second location in the nuclear fission traveling wave reactor core 12.
  • the second location is different from the first location.
  • a migration is determined of the at least one nuclear fission fuel assembly 14 in a second direction from the second location.
  • the second direction is different from the first direction.
  • the method 800 stops at a block 808.
  • the first direction may be outwardly and the second direction may be inwardly.
  • the first locations and the second locations may be based various attributes or parameters, such as without limitation: geometrical proximity to a central portion of the reactor core 12; neutron flux such that neutron flux at the first locations is greater than neutron flux at the second locations; and/or reactivity such that effective a the first locations is greater than keffective at the second locations.
  • the first direction may be inwardly and the second direction may be outwardly.
  • the second locations and the first locations may be based on various attributes or parameters, such as without limitation: geometrical proximity to a central portion of the reactor core 12; neutron flux such that neutron flux at the second locations is greater than neutron flux at the first locations; and/or reactivity such that keffective at the second locations is greater than keffective at the first locations.
  • a method 900 is provided for operating a nuclear fission traveling wave reactor.
  • the method 900 starts at a block 902.
  • at a block 904 at least one nuclear fission fuel assembly 14 is migrated in a first direction from a first location in the nuclear fission traveling wave reactor core 12 to a second location in the nuclear fission traveling wave reactor core 12.
  • the second location is different from the first location.
  • at a block 906 the at least one nuclear fission fuel assembly 14 is migrated in a second direction from the second location.
  • the second direction is different from the first direction.
  • the method 900 stops at a block 908.
  • the first direction may be outwardly and the second direction may be inwardly.
  • the first locations and the second locations may be based various attributes or parameters, such as without limitation: geometrical proximity to a central portion of the reactor core 12; neutron flux such that neutron flux at the first locations is greater than neutron flux at the second locations; and/or reactivity such that Ineffective at the first locations is greater than keffective at the second locations.
  • the first direction may be inwardly and the second direction may be outwardly.
  • the second locations and the first locations may be based on various attributes or parameters, such as without limitation: geometrical proximity to a central portion of the reactor core 12; neutron flux such that neutron flux at the second locations is greater than neutron flux at the first locations; and/or reactivity such that effective at the second locations is greater than keffective at the first locations.
  • a method 1000 for operating a nuclear fission reactor.
  • the method 1000 starts at a block 1002.
  • a predetermined burnup level is selected.
  • a migration is determined of selected ones of nuclear fission fuel assemblies in a nuclear fission reactor core in a manner to achieve a burnup level equalized toward the predetermined burnup level in substantially all of the nuclear fission fuel assemblies.
  • the method 1000 stops at a block 1008.
  • the selected ones of the nuclear fission fuel assemblies may be migrated in a nuclear fission reactor core in a manner responsive to the determined migration.
  • removal may be determined of respective selected ones of the nuclear fission fuel assemblies when burnup level is equalized toward the predetermined burnup level.
  • the selected ones of the nuclear fission fuel assemblies may be removed responsive to the determined removal.
  • an implementer may opt for a mainly hardware and/or firmware vehicle; alternatively, if flexibility is paramount, the implementer may opt for a mainly software implementation; or, yet again alternatively, the implementer may opt for some combination of hardware, software, and/or firmware.
  • any vehicle to be utilized is a choice dependent upon the context in which the vehicle will be deployed and the specific concerns (e.g., speed, flexibility, or predictability) of the implementer, any of which may vary.
  • Those skilled in the art will recognize that optical aspects of implementations will typically employ optically-oriented hardware, software, and or firmware.
  • logic and similar implementations may include software or other control structures.
  • Electronic circuitry may have one or more paths of electrical current constructed and arranged to implement various functions as described herein.
  • one or more media may be configured to bear a device-detectable implementation when such media hold or transmit device detectable instructions operable to perform as described herein.
  • implementations may include an update or modification of existing software or firmware, or of gate arrays or programmable hardware, such as by performing a reception of or a transmission of one or more instructions in relation to one or more operations described herein.
  • an implementation may include special-purpose hardware, software, firmware components, and/or general-purpose components executing or otherwise invoking special-purpose components. Specifications or other implementations may be transmitted by one or more instances of tangible transmission media as described herein, optionally by packet transmission or otherwise by passing through distributed media at various times.
  • implementations may include executing a special- purpose instruction sequence or invoking circuitry for enabling, triggering, coordinating, requesting, or otherwise causing one or more occurrences of virtually any functional operations described herein.
  • operational or other logical descriptions herein may be expressed as source code and compiled or otherwise invoked as an executable instruction sequence.
  • implementations may be provided, in whole or in part, by source code, such as C++, or other code sequences.
  • source or other code implementation may be compiled/ /implemented/translated/converted into a high-level descriptor language (e.g., initially implementing described technologies in C or C++ programming language and thereafter converting the prograniming language implementation into a logic-synthesizable language implementation, a hardware description language implementation, a hardware design simulation implementation, and/or other such similar mode(s) of expression).
  • a high-level descriptor language e.g., initially implementing described technologies in C or C++ programming language and thereafter converting the prograniming language implementation into a logic-synthesizable language implementation, a hardware description language implementation, a hardware design simulation implementation, and/or other such similar mode(s) of expression.
  • a logical expression e.g., computer programming language implementation
  • a Verilog-type hardware description e.g., via Hardware Description Language (HDL) and/or Very High Speed Integrated Circuit Hardware Descriptor Language (VHDL)
  • VHDL Very High Speed Integrated Circuit Hardware Descriptor Language
  • Those skilled in the art will recognize how to obtain, configure, and optimize suitable transmission or computational elements, material supplies, actuators, or other structures in light of these teachings.
  • Examples of a signal bearing medium include, but are not limited to, the following: a recordable type medium such as a floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), a digital tape, a computer memory, etc.; and a transmission type medium such as a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link (e.g., transmitter, receiver, transmission logic, reception logic, etc.), etc.).
  • a recordable type medium such as a floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), a digital tape, a computer memory, etc.
  • a transmission type medium such as a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link (e.g., transmitter, receiver, transmission logic, reception
  • electromechanical system includes, but is not limited to, electrical circuitry operably coupled with a transducer (e.g., an actuator, a motor, a piezoelectric crystal, a Micro Electro Mechanical System (MEMS), etc.), electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer configured by a computer program which at least partially carries out processes and/or devices described herein, or a microprocessor configured by a computer program which at least partially carries out processes and/or devices described herein), electrical circuitry forming a memory device (e.g., forms of memory (e.g., random access, flash, read only, etc.)), electrical circuitry forming a commumcations device (e.g., a modem, communications switch, optical-electrical equipment, etc.), and
  • a transducer e.g
  • electro-mechanical systems include but are not limited to a variety of consumer electronics systems, medical devices, as well as other systems such as motorized transport systems, factory automation systems, security systems, and/or communication/computing systems.
  • electro-mechanical as used herein is not necessarily limited to a system that has both electrical and mechanical actuation except as context may dictate otherwise.
  • any two components so associated can also be viewed as being “operably connected”, or “operably coupled,” to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being “operably couplable,” to each other to achieve the desired functionality.
  • operably couplable include but are not limited to physically mateable and/or physically interacting components, and/or wirelessly interactable, and/or wirelessly interacting components, and/or logically interacting, and/or logically interactable components.
  • the method comprising: propagating a nuclear fission traveling wave burnfront along first and second dimensions within a plurality of nuclear fission fuel .
  • the first locations include inward locations; and the second locations include outward locations.
  • the method of clause 13, wherein the inward locations and the outward locations are based on reactivity such that keffective at the inward locations is greater than keffective at the outward locations.
  • the method of clause 1, wherein the first locations and the second locations are located on opposite sides of a reference value along the first dimension.
  • controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations includes rotating at least one of the selected ones of the plurality of nuclear fission fuel subassemblies.
  • controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations includes inverting at least one of the selected ones of the plurality of nuclear fission fuel subassemblies.
  • the selected set of dimensional constraints includes a predetermined maximum distance along the second dimension.
  • the selected set of dimensional constraints is a function of at least one burnfront criteria.
  • the method of clause 25, wherein the burnfront criteria includes neutron flux.
  • the neutron flux is associated with at least one of the selected ones of the plurality of nuclear fission fuel subassemblies.
  • the burnfront criteria includes neutron fluence.
  • the method of clause 28, wherein the neutron fluence is associated with at least one of the selected ones of the plurality of nuclear fission fuel subassemblies.
  • the method of clause 25, wherein the burnfront criteria includes burnup.
  • the method of clause 30, wherein the burnup is associated with at least one of the selected ones of the plurality of nuclear fission fuel subassemblies.
  • the method of clause 25, wherein the burnfront criteria includes burafront location within at least one of the selected ones of the plurality of nuclear fission fuel subassemblies.
  • controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations includes controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies radially along the first dimension from respective first locations toward respective second locations.
  • controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations includes controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies spirally along the first dimension from respective first locations toward respective second locations.
  • controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations includes controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies axially along the first dimension from respective first locations toward respective second locations.
  • shape of the nuclear fission traveling wave burnfront is substantially spherical.
  • shape of the nuclear fission traveling wave burnfront substantially conforms to a selected continuously curved surface.
  • the shape of the nuclear fission traveling wave burnfront is substantially rotationally symmetrical around the second dimension.
  • the method of clause 1, wherein the shape of the nuclear fission traveling wave burnfront has substantial n-fold rotational symmetry around the second dimension.
  • the method of clause 1, wherein the shape of the nuclear fission traveling wave burnfront along the second dimension is asymmetrical.
  • the method of clause 40, wherein the shape of the nuclear fission traveling wave burnfront is rotationally asymmetrical around the second dimension.
  • removing at least one of the plurality of nuclear fission traveling wave igniter assemblies prior to controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations includes removing at least one of the plurality of nuclear fission traveling wave igniter assemblies from the second locations prior to controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations.
  • the method of clause 45 wherein causing the nuclear fission traveling wave reactor to become subcritical includes inserting neutron absorbing material into the reactor core.
  • the method of clause 45 further comprising re-establishing criticality after controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations.
  • the method of clause 47 wherein re-establishing criticality includes removing at least a portion of neutron absorbing material from the reactor core.
  • the method of clause 45 further comprising shutting down the nuclear fission traveling wave reactor prior to controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations.
  • the method of clause 49 further comprising re-starting the nuclear fission traveling wave reactor after controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations.
  • a method of controlling a nuclear fission traveling wave reactor comprising: for a nuclear fission traveling wave burnfront propagating along first and second dimensions, determining a desired shape of the nuclear fission traveling wave burnfront along the second dimension within a plurality of nuclear fission fuel subassemblies according to a selected set of dimensional constraints; and determining a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape.
  • determining a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape includes determining a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner to establish the desired shape.
  • determining a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape includes determining a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner to maintain the desired shape.
  • dimensional constraints includes a predetermined maximum distance along the second dimension.
  • dimensional constraints is a function of at least one burnfront criteria.
  • detenriining a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations includes - ⁇ detenriining a radial migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations.
  • determining a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations includes determining a spiral migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations.
  • determining a desired shape of the nuclear fission traveling wave burnfront includes determining a substantially spherical shape of the nuclear fission traveling wave burnfront.
  • determining a desired shape of the nuclear fission traveling wave burnfront along the second dimension includes determining a continuously curved surface shape of the nuclear fission traveling wave burnfront.
  • a system comprising: for a nuclear fission traveling wave bumfront propagating along first and second dimensions, first electrical circuitry configured to determine a desired shape of the nuclear fission traveling wave burnfront along the second dimension within a plurality of nuclear fission fuel subassemblies according to a selected set of dimensional constraints; and second electrical circuitry configured to determine a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape.
  • circuitry is further configured to determine an existing shape of the nuclear fission traveling wave burnfront.
  • circuitry is further configured to determine a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner to establish the desired shape.
  • circuitry is further configured to determine a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner to maintain the desired shape.
  • circuitry is further configured to determine a time when to migrate the selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape.
  • dimensional constraints is a function of at least one bumfront criteria.
  • circuitry is further configured to determine a spiral migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations.
  • circuitry is further configured to determine an axial translation of selected ones of the plurality of nuclear fission fuel subassemblies.
  • a computer software program product comprising: first computer-readable media software program code configured to determine, for a nuclear fission traveling wave bumfront propagating along first and second dimensions, a desired shape of the nuclear fission traveling wave bumfront along the second dimension within a plurality of nuclear fission fuel subassemblies according to a selected set of dimensional constraints; and second computer-readable media software program code configured to determine a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape.
  • the second locations include outward locations.
  • the second computer-readable media software program code includes fifth computer-readable media software program code configured to determine an axial translation of selected ones of the plurality of nuclear fission fuel subassemblies.
  • first computer-readable media software program code includes seventh computer-readable media software program code configured to determine a substantially spherical shape of a nuclear fission traveling wave burnfront.
  • first computer-readable media software program code includes eighth computer-readable media software program code configured to determine a continuously curved surface shape of the nuclear fission traveling wave burnfront.
  • the desired shape of the nuclear fission traveling wave burnfront is substantially rotationally symmetrical around the second dimension.
  • a system comprising: for a nuclear fission traveling wave burnfront propagating along first and second dimensions, first electrical circuitry configured to determine a desired shape of the nuclear fission traveling wave burnfront along the second dimension within a plurality of nuclear fission fuel subassemblies according to a selected set of dimensional constraints; second electrical circuitry configured to determine a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape; and a subassembly configured to migrate selected ones of the plurality of nuclear fission fuel subassemblies responsive to the second electrical circuitry.
  • the second electrical circuitry is further configured to determine a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner to maintain the desired shape. 191. The system of clause 187, wherein the second electrical circuitry is further configured to determine a time when to migrate the selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner responsive to the desired shape.
  • a nuclear fission traveling wave reactor comprising: a nuclear fission traveling wave reactor core; a plurality of nuclear fission fuel subassemblies received in the nuclear fission traveling wave reactor core, each of the plurality of nuclear fission fuel subassemblies being configured to propagate a nuclear fission traveling wave burnfront therein along first and second dimensions; first electrical circuitry configured to determine a desired shape of the nuclear fission traveling wave burnfront along the second dimension within a plurality of nuclear fission fuel subassemblies according to a selected set of dimensional constraints; second electrical circuitry configured to determine a migration of selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations toward respective second locations in a manner- responsive to the desired shape; and a subassembly configured to migrate selected ones of the plurality of nuclear fission fuel subassemblies responsive to the second electrical circuitry.
  • circuitry is further configured to determine a substantially spherical shape of the nuclear fission traveling wave burnfront.
  • circuitry is further configured to determine a continuously curved surface shape of the nuclear fission traveling wave burnfront. 261.
  • a method of operating a nuclear fission traveling wave reactor comprising: migrating at least one nuclear fission fuel assembly outwardly from a first location in a nuclear fission traveling wave reactor core to a second location in the nuclear fission traveling wave reactor core.
  • a method of operating a nuclear fission traveling wave reactor comprising: determining a migration of at least one nuclear fission fuel assembly in a first direction from a first location in a nuclear fission traveling wave reactor core to a second location in the nuclear fission traveling wave reactor core, the second location being different from the first location; and determining a migration of the at least one nuclear fission fuel assembly in a second direction from the second location, the second direction being different from the first direction.
  • a method of operating a nuclear fission traveling wave reactor comprising: migrating at least one nuclear fission fuel assembly in a first direction from a first location in a nuclear fission traveling wave reactor core to a second location in the nuclear fission traveling wave reactor core, the second location being different from the first location; and determining a migration of the at least one nuclear fission fuel assembly in a second direction from the second location, the second direction being different from the first direction.
  • a method of operating a nuclear fission traveling wave reactor comprising: migrating at least one nuclear fission fuel assembly in a first direction from a first location in a nuclear fission traveling wave reactor core to a second location in the nuclear fission traveling wave reactor core, the second location being different from the first location; and migrating the at least one nuclear fission fuel assembly in a second direction from the second location, the second direction being different from the first direction.
  • a method of operating a nuclear fission reactor comprising: selecting a predetermined burnup level; and determining a migration of selected ones of a plurality of nuclear fission fuel assemblies in a nuclear fission reactor core in a manner to achieve a burnup level equalized toward the predetermined burnup level in substantially all of the plurality of nuclear fission fuel assemblies.

Abstract

Les modes de réalisation de cette invention concernent des procédés et des systèmes de migration d'assemblages combustibles dans un réacteur à fission nucléaire, des procédés de fonctionnement d'un réacteur à fission nucléaire à onde progressive, des procédés de commande d'un réacteur à fission nucléaire à onde progressive, des systèmes de commande d'un réacteur à fission nucléaire à onde progressive, des produits programmes de logiciels informatiques pour commander un réacteur à fission nucléaire à onde progressive, et des réacteurs à fission nucléaire à onde progressive dotés de systèmes de migration d'assemblages combustibles.
EP10844848A 2009-11-06 2010-11-05 Procédés et systèmes pour la migration d'assemblages combustibles dans un réacteur à fission nucléaire Withdrawn EP2497089A2 (fr)

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US12/590,448 US10008294B2 (en) 2009-11-06 2009-11-06 Methods and systems for migrating fuel assemblies in a nuclear fission reactor
US12/657,735 US9786392B2 (en) 2009-11-06 2010-01-25 Methods and systems for migrating fuel assemblies in a nuclear fission reactor
US12/657,725 US9922733B2 (en) 2009-11-06 2010-01-25 Methods and systems for migrating fuel assemblies in a nuclear fission reactor
US12/657,726 US9799416B2 (en) 2009-11-06 2010-01-25 Methods and systems for migrating fuel assemblies in a nuclear fission reactor
PCT/US2010/002907 WO2011093842A2 (fr) 2009-11-06 2010-11-05 Procédés et systèmes pour la migration d'assemblages combustibles dans un réacteur à fission nucléaire

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EP10828672A Withdrawn EP2497091A1 (fr) 2009-11-06 2010-11-05 Procédés et systèmes de migration d'ensembles combustibles dans un réacteur à fission nucléaire
EP10844848A Withdrawn EP2497089A2 (fr) 2009-11-06 2010-11-05 Procédés et systèmes pour la migration d'assemblages combustibles dans un réacteur à fission nucléaire
EP10844847.3A Ceased EP2497088A4 (fr) 2009-11-06 2010-11-05 Procédés et systèmes pour la migration d'assemblages combustibles dans un réacteur à fission nucléaire

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KR102004542B1 (ko) 2019-07-26
JP2013510313A (ja) 2013-03-21
CN102696073A (zh) 2012-09-26
EA024235B1 (ru) 2016-08-31
WO2011093845A3 (fr) 2011-10-06
JP6166535B2 (ja) 2017-07-19
EA201290223A1 (ru) 2012-10-30
RU2557257C2 (ru) 2015-07-20
CN102714064A (zh) 2012-10-03
WO2011093841A3 (fr) 2011-11-24
KR20120093325A (ko) 2012-08-22
KR20120083507A (ko) 2012-07-25
RU2557563C9 (ru) 2015-11-20
RU2562063C2 (ru) 2015-09-10
WO2011093842A2 (fr) 2011-08-04
BR112012010800A2 (pt) 2016-03-29
KR101987479B1 (ko) 2019-06-10
CN102714067B (zh) 2018-05-29
CN102714066B (zh) 2016-08-17
JP6162403B2 (ja) 2017-07-12
EP2497088A2 (fr) 2012-09-12
JP6025565B2 (ja) 2016-11-16
CN102714067A (zh) 2012-10-03
CN102714066A (zh) 2012-10-03
JP2016048268A (ja) 2016-04-07
RU2012120916A (ru) 2013-12-20
CN102714064B (zh) 2015-11-25
KR102017897B1 (ko) 2019-09-03
CN102696073B (zh) 2018-05-18
WO2011093842A3 (fr) 2011-10-20
JP6255426B2 (ja) 2017-12-27
JP2013510310A (ja) 2013-03-21
WO2011093841A2 (fr) 2011-08-04
RU2557563C2 (ru) 2015-07-27
EP2497091A1 (fr) 2012-09-12
WO2011093845A2 (fr) 2011-08-04
WO2011056235A1 (fr) 2011-05-12
JP2013510314A (ja) 2013-03-21
KR20120087163A (ko) 2012-08-06
JP6026887B2 (ja) 2016-11-16
EP2497087A2 (fr) 2012-09-12
RU2012120915A (ru) 2013-12-20
BR112012010799A2 (pt) 2016-03-29
KR20120093323A (ko) 2012-08-22
JP2013510309A (ja) 2013-03-21
BR112012010797A2 (pt) 2016-03-29
EP2497088A4 (fr) 2017-03-15
RU2012120918A (ru) 2013-12-20
KR101986381B1 (ko) 2019-06-05

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