EP0570360A1 - Systeme de refroidissement de reacteur nucleaire - Google Patents

Systeme de refroidissement de reacteur nucleaire

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Publication number
EP0570360A1
EP0570360A1 EP90908442A EP90908442A EP0570360A1 EP 0570360 A1 EP0570360 A1 EP 0570360A1 EP 90908442 A EP90908442 A EP 90908442A EP 90908442 A EP90908442 A EP 90908442A EP 0570360 A1 EP0570360 A1 EP 0570360A1
Authority
EP
European Patent Office
Prior art keywords
coolant
flow channel
primary
reactor
cooling system
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Withdrawn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
EP90908442A
Other languages
German (de)
English (en)
Inventor
John S. Hewitt
Hani C. Ajus
John C. Atkinson
Thomas C. Currie
Bruce M. Pearson
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.)
ECS-POWER SYSTEMS Inc
Original Assignee
ECS-POWER SYSTEMS Inc
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
Application filed by ECS-POWER SYSTEMS Inc filed Critical ECS-POWER SYSTEMS Inc
Publication of EP0570360A1 publication Critical patent/EP0570360A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21D—NUCLEAR POWER PLANT
    • G21D9/00—Arrangements to provide heat for purposes other than conversion into power, e.g. for heating buildings
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C11/00—Shielding structurally associated with the reactor
    • G21C11/02—Biological shielding ; Neutron or gamma shielding
    • G21C11/04—Biological shielding ; Neutron or gamma shielding on waterborne craft
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C15/00—Cooling arrangements within the pressure vessel containing the core; Selection of specific coolants
    • G21C15/18—Emergency cooling arrangements; Removing shut-down heat
    • 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

  • This invention relates to a cooling system for particular class of water-cooled nuclear power reactor said reactor having (a) a high-temperature (limited by boiling considerations) primary heat transport circuit which dominates the reactor cooling process under normal operating conditions; (b) a large pool of cool water surrounding or otherwise in the vicinity of the reactor core region and forming a component of the shutdown cooling circuit which may be said to be passive; which is to say that, in the post shutdown phase of reactor operation, adequate core cooling is assured for an extended period of time, independently of any sensing devices, externally energized components, or operator intervention, and (c) a shutdown cooling circuit which is itself passive in the initiation of its operation; which is to say that the shutdown cooling circuit initiates its function without reliance on sensors, externally energized components, mechanical actuation, or operator action.
  • the invention relates to a cooling system for a nuclear reactor of the type in which the coolant liquid is normally circulated around the primary heat transport circuit which includes the reactor core, various heat exchangers, and a primary circulation pump.
  • the primary heat transport circuit which includes the reactor core, various heat exchangers, and a primary circulation pump.
  • Located in this circuit and at points not far above and below the core are the very important aspects of this invention, namely, three-way flow branching devices herein referred to as "hydrodynamic ports", or just “ports".
  • the role of the. ports is to provide free flow-through passage of the coolant in the primary heat transport circuit as long as normal reactor operating conditions prevail, and to provide at all times for sizable branch-flow when the passive shutdown cooling circuit, which includes the pool liquid, comes into operation under various abnormal operating conditions.
  • ports that they perform the above functions automatically, and do not involve any sensors, externally energized components, mechanical actuation, or operator action for either the maintenance of normal operation with high performance, or for the transition to, or sustaining of, the safe shutdown condition.
  • the ports when functioning in support of normal operation, involve hydrodynamic principles applied in an integrated way to the overall thermal-hydraulic configuration, but require minimal complexity of associated equipment to sustain normal as well as shutdown operation.
  • it is characteristic of the invention that it is applicable to a variety of reactor plants to be deployed under unusual combinations of constraints of space, weight, mobility, etc.
  • the invention relates in the first instance to water cooled nuclear power reactors, the invention can be employed to advantage in other types of reactor, including those cooled by media other than water and those which may be used predominantly for research purposes.
  • Prior art reactors have been described (though they have not yet been constructed or operated) in which passive shutdown cooling is available to cover a range of potential accident situations, and in which the primary heat transport circuit, under normal operating conditions, is maintained in thermal-hydraulic isolation from the shutdown circuit.
  • These reactors are known as the PIUS (described in Canadian Patent 1,173,570 (Hannerz) ; the SECURE (described in Canadian Patent 1,070,860 (Blomstrand et al.); the TRIGA power reactor, described in R.W.
  • TRIGA Power System A Passive Safe Co- Generation Unit for Electric Power and Low Temperature Heat
  • IAEA-TECDOC-463 International Atomic Energy Agency, Vienna, 1988
  • GEYSER heating reactor described in G. Vecsey and P.G.K. Doroszlai, "GEYSER, A Simple, New Heating Reactor of High Inherent Safety", Nuclear Engineering and Design, 109 (1988) 141- 145.
  • the PIUS, SECURE and TRIGA reactors rely on elaborate parameter-sensing and control systems to continuously maintain the integrity of normal reactor operations in the face of the inevitable adverse influences of the passive cooling system on normal operations.
  • the invention provides a cooling system for use in association with a nuclear reactor plant of the type having a primary cooling circuit comprising a reactor core, an inlet duct and inlet plenum for conducting coolant into the core, an outlet plenum and an outlet duct for conducting coolant out of the core, and means for circulating coolant through the primary cooling circuit.
  • the cooling system comprises: (a) a reserve coolant tank for containing coolant; (b) a first port means in the inlet duct upstream of the core, having a primary flow channel for conducting coolant through the inlet duct and having exchange flow channel means for conducting coolant between the reserve coolant tank and the primary flow channel, the primary flow channel being open to said reserve coolant tank through the exchange flow channel means; and (c) a second port means in the outlet duct downstream of the core, and spaced generally above the first port means, having a primary flow channel for conducting coolant through the outlet duct and having exchange flow channel means for conducting coolant between the primary flow channel and the reserve coolant tank, the primary flow channel being open to the reserve coolant tank through the exchange flow channel means.
  • coolant circulates through the primary cooling circuit and only minimal volumes of coolant flow into the reserve coolant tank from the primary cooling circuit or into said primary cooling circuit from the reserve coolant tank through said exchange flow channel means.
  • a natural convective flow of coolant is initiated without mechanical or operator intervention, wherein coolant in the reactor core flows by convection through the outlet plenum and outlet duct and through said exchange flow channel means in the second port means into the reserve coolant tank, and coolant in the reserve coolant tank flows into the exchange flow channel means in the first port means, through the inlet duct and inlet plenum and into the reactor core, whereby a natural convective flow of coolant results.
  • the invention also provides a cooling system for use in association with a nuclear reactor plant of the type having a primary cooling circuit comprising a reactor core, a plurality of inlet ducts and an inlet plenum for conducting coolant into the core, an outlet plenum and a plurality of outlet ducts for conducting coolant from the core, the inlet ducts and the outlet ducts being configured with substantially radial symmetry about a vertical axis through the center of the core, and means for circulating coolant through the primary cooling circuit.
  • the cooling system comprises: (a) a reserve coolant tank for containing coolant; (b) a first port means in each of the inlet ducts upstream of the core, each of the first port means having a primary flow channel for conducting coolant through the inlet duct and having exchange flow channel means for conducting coolant between the reserve coolant tank and the primary flow channel, the primary flow channel being open to the reserve coolant tank through the exchange flow channel means; (c) a second port means in each of the outlet ducts downstream of the core, and spaced generally at higher elevation than each of the first port means in the normal orientation of the reactor plant, each of the second port means having a primary flow channel for conducting coolant through the outlet duct and having exchange flow channel means for conducting coolant between the primary flow channel and the reserve coolant tank, the primary flow channel being open to the reserve coolant tank through the exchange flow channel means.
  • coolant circulates through the primary cooling circuit and only minimal volumes of coolant flow into the reserve coolant tank from the primary cooling circuit or into the primary cooling circuit from the reserve coolant tank through the exchange flow channel means.
  • a natural convective flow of coolant is initiated without mechanical or operator intervention, and irrespective of the orientation of the reactor plant with respect to gravity, wherein coolant in the reactor core flows by convection generally upward through at least some of the outlet ducts and/or inlet ducts positioned at a higher elevation than the reactor core and through the exchange flow channel means in the second and/or first port means in the ducts and into the reserve coolant tank, and coolant in the reserve coolant tank flows into the exchange flow channel means in the first and /or second port means in at least some of the inlet and/or outlet ducts positioned lower than the core, and into the reactor core,
  • An objective of the present invention is to allow the operation of a nuclear reactor having a primary circuit, a shutdown circuit, and, especially, a manner of coupling the two circuits such that:
  • the performance of the primary circuit under normal operating conditions is not significantly compromised by the presence of the (passively coupled) shutdown circuit.
  • the shutdown circuit performs as indicated above, namely, it adequately cools the reactor core on a passive basis in the face of a variety of accident scenarios following self-initiation of the passive cooling function, such initiation being also on a passive basis.
  • the passive shutdown system in both its initiation and sustained operation, is free of encumbrances which could conceivably invalidate the assumption of passive behaviour.
  • the primary circuit operates in the prescribed manner but with a bare minimum of active devices (e.g., sensors, pumps, actuators, valves, hydrodynamic shims, feed-back circuits, central processing units, operator monitoring and intervention) being required to maintain operation at the prescribed performance level.
  • active devices e.g., sensors, pumps, actuators, valves, hydrodynamic shims, feed-back circuits, central processing units, operator monitoring and intervention
  • This requirement is in the interests of: (a) minimizing the complexity and costs associated with the engineering, detailed design, construction, operation and maintenance of the plant; (b) maximizing reliability, safety, and licensability of the nuclear plant; and (c) freeing the basic passive safety design from additional complexities that would restrict the range of application of a reactor. (Some applications, which may stand to gain the most from passive cooling, may also impose overriding requirements excluding a more complex form of passive safety.)
  • the fundamental principles are universally adaptable to a sufficient degree that the basic reactor design, including the approach to incorporating passively initiated passive cooling, can be applied to advantage in a range of circumstances, including the following, taken individually or in combination: (a) a range of power output ratings; (b) a range of power reactor purposes, including those for space and process heating and those producing shaft power or electricity; (c) pool-type research reactors where the thermal-hydraulic configuration of the invention permits: (i) enhanced cooling, and thus higher sustained levels of power and, hence, neutron flux, for a given fixed reactivity margin, and (ii) effective localization of activation products within the primary transport circuit; (d) limited head space above the reactor as in submarine applications of reactors; (e) varying orientation of reactor plant (which translates as variability of the gravitational g-vector) , as in the case of a submarine-borne reactor during either normal operation at sea, or when capsized; (f) varying magnitude of the acceleration due to gravity during reactor operation, as for a submarine-borne submarine
  • the primary heat transport circuit which is otherwise of a more-or-less standard closed circuit design (i.e., with the coolant being circulated through the reactor loop core and the heat exchanging components by means of a pump) is fitted with branching devices called hydrodynamic ports in such a way that passive cooling is continuously available by process- inherent means to assure that the reactor is always adequately cooled, even following a range of events which would ordinarily lead to accident scenarios. It is a feature of the hydrodynamic ports and fundamental in the manner of their deployment that they permit reactors embracing a broad range of types, configurations and purposes to be accommodated in respect of the stated objectives of the patent, without significantly restricting or complicating plant design or operation.
  • Figure 1 is a sectional elevation of one embodiment of the invention
  • Figure 2a is an axial view of a hydrodynamic port
  • Figure 2b is a cross-section along the line AA of Figure 2a
  • Figure 3a is an axial view of a hydrodynamic port having bypass ducts
  • Figure 3b is a sectional view along the line AA of Figure 3a;
  • Figure 3c is a sectional view along the line BB of Figure 3a;
  • Figure 4a is an axial view of a hydrodynamic port with an anti-convective shroud fitted thereon;
  • Figure 4b is a sectional view along the line CC of Figure 4a;
  • Figure 5 is a sectional elevation of a second embodiment of the invention.
  • Figure 6 is a sectional elevation of a third embodiment of the invention.
  • the primary heat transport circuit comprises the equipment components normally found in a typical reactor cooling system of the closed circuit variety. Included are the reactor core 1 and the inlet and outlet plena, 2 and 3, respectively, all located inside the reactor vessel 46. Also included are the inlet and outlet ducts, 4 and 5, respectively, leading by means of inlet and outlet conduits 11 and 10, respectively, through penetrations in the walls of the reserve coolant tank 14 to connect with external components, principally the main circulating pump and combinations of heat exchanging components, such as preheaters, evaporators, steam generators, or simple heat exchangers.
  • the reactor core 1 and the inlet and outlet plena, 2 and 3, respectively, all located inside the reactor vessel 46. Also included are the inlet and outlet ducts, 4 and 5, respectively, leading by means of inlet and outlet conduits 11 and 10, respectively, through penetrations in the walls of the reserve coolant tank 14 to connect with external components, principally the main circulating pump and combinations of heat exchanging components, such as preheaters, evaporators, steam generators,
  • the coolant circulating within the primary circuit will be at temperatures considerably higher (typically by 80 - 250°C) than the reserve coolant maintained in the reserve coolant tank 14.
  • Thermally insulating layers 9 of a design suitable for such applications are attached to most of the primary circuit boundaries lying within the reserve coolant tank. Such insulation enhances the energy delivery efficiency of the reactor and facilitates the maintaining of the reserve coolant at a standby temperature sufficiently low to support safety objectives.
  • the role of the insulation in enhancing the actual operation of the passive cooling circuit is not necessarily of importance, however, in meeting most specific reactor safety requirements.
  • the reserve coolant is maintained at suitable standby temperatures with the aid of reserve tank coolers (not shown in the drawings) which transport, to the external environment, residual heat transferred from the primary circuit to the reserve tank during normal operations, and also the decay heat transferred to the reserve tank by the passive cooling circuit following emergency shutdown.
  • the reserve tank coolers may operate on either active or passive principles but, for consistency with the passive safety principles of the present invention, the capacity of the passive cooling component of the reserve tank coolers should be adequate for safe decay heat removal over an indefinitely long period following reactor shutdown.
  • the specific design of the reserve tank coolers may be carried out by persons skilled in the art of heat transfer as required to suit the particular reactor and the circumstances of its application.
  • the elements of the primary heat transport circuit not ordinarily found in a reactor cooling system, but which are a key feature of the present invention, are the inlet and outlet hydrodynamic ports, 7 and 8, located in the circuit just upstream from the inlet duct 4 and downstream from the outlet duct 5, respectively.
  • the hydrodynamic ports exemplified by the basic version shown in Figure 2, exhibit specific hydrodynamic properties when correctly incorporated in the design of a reactor primary heat transport circuit.
  • ports' capabilities of: (i) supporting to a high degree the continuity of primary circuit flow between the ducts 21 and 22 in normal reactor operating conditions, (ii) offering large resistance against a tendency toward both combining and dividing branch flows through the exchange flow slots 20, relative to port axial flows, when the system temperatures, primary flow or reactor orientation deviate inadvertently from normal, and (iii) offering relatively small resistance to large branch flows of either the combining or dividing kind in severely abnormal or accident conditions, such as when the main circulating pump has stopped. Under these latter conditions, core cooling relies solely on naturally convective coolant circulation, established and maintained by inherent processes.
  • the operative convective circuit in such conditions is between the core 1 and the reserve coolant tank 14 and is referred to herein as the passive cooling circuit.
  • a principal flow pattern for natural convection is depicted by the broken arrows in Figure 1.
  • the solid arrows show the flow pattern in the primary cooling circuit under normal operating conditions with the circulating pump on.
  • the above-mentioned properties of the hydrodynamic ports are manifest in the first embodiment of the present invention as it applies to the reactor plant of Figure 1.
  • a detailed description of the operation of the cooling system of this plant follows. As implied above, under normal operating conditions a steady flow is maintained through the primary circuit by the continuous operation of the circulating pump.
  • the pumping head equals the algebraic sum of the pressure changes across individual circuit components, including (i) the heat exchanger components located externally to the reserve cooling tank as referred to above, and (ii) the components forming that part of the circuit delineated by the solid arrows and shown residing inside the reserv coolant tank 14, namely (in flow sequence), the inle conduit 11, the inlet hydrodynamic port 7, the diffuser 6 the inlet leg 4, the inlet plenum 2, the reactor core 1 the outlet plenum 3, the outlet duct 5, the outle hydrodynamic port 8, and the outlet conduit 10.
  • the hydrodynamic ports, 7 and 8 ar designed (as clarified in Figure 2) to present no physica barrier against the flow of coolant between the primar cooling circuit and the reserve coolant tank 14.
  • Basic parameters of the primary circuit that must be taken into account in designing for zero net accumulative pressure are the primary circuit mass flow rate, the coolant temperature profile in the primary circuit, the bulk temperature of the coolant of the reserve coolant tank, and the resistive pressure drop due to the primary circuit mass flow through the core and other components in the flow path from port 7 to port 8. All such parameters will have been determined as the normal operating design values selected to yield optimal plant energy production, efficiency and safety, as appropriate to the intended application. More specifically, the criterion for meeting the requirement of zero net accumulative pressure may be expressed in terms of the values of A 2 and A 2 which are shown in Figure 1 as the axial flow areas associated with hydrodynamic ports 7 and 8, respectively.
  • the design criterion is simply that net accumulative elevation pressure be equal to resistive pressure losses along the flow path through core and between the ports. This criterion is met by adequate protraction of the vertical separation L betw the ports, and seeing that the segment of the prim circuit including the core and lying between the por itself now considerably lengthened as a consequence of increased port separation, is of a design consistent w good hydrodynamic practice.
  • a third example relating to the reactor depicted in Figure 1 sufficient vertical space is postulated so that, for the prescribed disposition of normal operating temperatures throughout the system, the distance L between the two ports can be made such that the net static head becomes more than sufficient to compensate the resistive pressure losses associated with the passage of the primary coolant at design mass flow rate through the core.
  • the zero net accumulative pressure requirement may be met by making A 2 smaller than &._ so that the dynamic pressure increment cancels the excess net elevation pressure over the resistive pressure loss across the core.
  • the excess net elevation pressure contributes, along with the circulating pump if one is present, to overcoming the resistive losses in those primary circuit components implied as lying outside the reserve coolant tank. Again, the careful application of hydraulic design practice is required.
  • a principal objective of the invention is to provide in a reactor cooling system, of otherwise ordinary but efficient design, a passive cooling system capability which is constantly available for deployment by process- inherent means during normal reactor operation, and which is capable of mitigating satisfactorily a set of reactor accident initiating events.
  • the hydrodynamic ports, 7 and 8 are designed to present no physical barrier against the flow of coolant between the primary cooling circuit and the reserve coolant tank 14. The principal means of avoiding the potentially deleterious effects of such an arrangement on the normal reactor operation is an important element of this invention. The operation of the cooling system in mitigating accidents effects is now described.
  • the coolant column of approximate height L 2 and temperature e-qual to the reactor outlet temperature serves as the hot leg, and the column of height L partially cancelled by the column of height 1__ , both columns being at the reserve coolant temperature, serves as the cold leg of the operative thermosyphon.
  • the primary heat transport system pressure boundary includes the reserve coolant tank and those components of the primary circuit indicated with respect to Figure 1 to lie outside the boundary of the reserve coolant tank, unless of course they too are located inside the reserve tank in the alternative arrangement mentioned earlier.
  • the reactor of Figure 1 is depicted as being maintained at an elevated operating pressure by means of the pressurizer 12 connected to the reserve coolant tank.
  • a liquid-vapour interface 13 is shown to be maintained in the pressurizer. If the reactor is to be operated nominally at atmospheric pressure, either the pressurizer, or the reserve tank itself, is left open to the atmosphere in the design, or is in some manner vented to atmosphere. The so-called (open) pool-type reactors fall into this latter category.
  • the principal objective of pressurizing the reactor coolant in any reactor plant is to permit the transport of heat at elevated temperatures, in the interest of enhancing the thermodynamic efficiency of the plant, while retaining the advantages of the coolant in its liquid state.
  • the reactor plant of Figure 1 only the coolant circulating in the primary circuit has a requirement for elevated temperatures in consideration of plant thermodynamics.
  • the reserve coolant may be maintained at relatively low temperatures; safety considerations require that it must be maintained by means of the tank coolers
  • Figure 1 in which the primary circuit and the reserve coolant tank are required to operate at identically regulated pressures, enhances the safety performance of the reactor in the event of a primary circuit pipe break. This follows since only the relatively small fraction of the total primary inventory which lies within the primary circuit itself is at a temperature exceeding the saturation temperature at the ambient pressure (normally one atmosphere) and is therefore subject to rapid vaporization and accompanying energy release at the instant of the break. The bulk of the reserve coolant inventory remains as cool liquid immediately following the break and serves to continue the core cooling function after entering the core region through the ports and eventually establishing a steady passive cooling flow.
  • the passive cooling system will continue to serve the reactor core cooling function for a considerable time following the pipe break.
  • the design may also call for a syphon break arrangement (not shown) between the two conduits in order to limit the extent of removal of reserve coolant by syphoning action. The potential for loss of coolant through rupture of the reserve coolant tank itself is minimized by care and redundancy in design.
  • reactivity-limiting mechanisms are not prescribed as a part of the present invention, but it is clear that if the reactivity reduction or shutdown action is inherent in the processes which are intimately related to the accident condition, then reactivity-limiting mechanisms can be seen to be consistent with inherent safety aspects of the cooling system.
  • Two reactivity-limiting mechanisms both of which are generally understood by persons skilled in the art of reactor design, are mentioned here briefly, however.
  • One is based on negative reactivity power coefficients associated with either the expansion of the coolant or the effect of fuel heating on either resonance absorption or neutron thermalization. The other is less direct and is initiated by the onset of passive cooling which, in turn, is triggered in response to the initiation and development of the accident scenario.
  • the first of these mechanisms may be adopted in the detailed design of a reactor such as the one in Figure 1, in the selection of the fuel type and associated core design.
  • the second mechanism may be implemented in the detailed design of a reactor such as that of Figure l by arranging for the permanent addition of heavily concentrated neutron absorber in solution with the reserve coolant, and placing neutron absorber only in mild solution with the primary coolant.
  • the reactor in this case, is regulated by actively varying the concentration of absorber in the primary circuit. Under normal operating conditions the two levels of solution are kept from mixing with one another as a byproduct of the arrangement described earlier as keeping the same two categories of coolant from mixing for reasons of both thermal efficiency and prudent radiological management.
  • the reactor cooling system of Figure 1 does not place any daunting restrictions on the operating protocol of the reactor plant.
  • the primary circuit pump may first be turned on, in which case there will be a significant bypass exchange flow in which some circulating primary coolant enters the reserve tank through the inlet port 7, while an equivalent flow of reserve coolant passes into the primary circuit through the outlet port 8.
  • the primary circuit warms more quickly than does the reserve coolant and, by the time the primary circuit reaches the normal operating temperature, it will have ceased altogether to exchange with the reserve coolant.
  • a less likely alternative start up procedure is to first bring the reactor to an operating power level while relying on the convective flow of the passive system for core cooling. As the pumped cooling circuit is brought on line, the initial ingress flow of the passive cooling is gradually reduced to zero and the normal operating conditions are reached.
  • FIG. 2 A detailed representation of a basic version of the hydrodynamic port, of a kind suitable for implementation in the cooling system of the reactor of Figure l, is shown in Figure 2.
  • This port constitutes an approximation of a continuous pipe made up of two flow area defining ducts 21 and 22 with attached flanges 23, separated axially by the branch opening composed of a series of several slot-defining plates 24 alternating with spacers 25 which give rise to the circumferential exchange flow slots 20.
  • the port structure shown in Figure 2 is seen to be supportive of the first two of the previously mentioned important properties of the hydrodynamic ports, namely, (i) the support of the continuity of primary circuit flow between the flow area defining ducts 21 and 22 in normal reactor operating conditions, and (ii) the offering of large resistances to both combining and dividing branch flows, when the tendency for such is created due to the inadvertent deviation of principal operating parameters, such as coolant temperatures and primary flow rates, from nominal values.
  • the third of the previously mentioned important properties of the hydrodynamic ports namely, the offering of relatively small resistances to large branch flows, of either kind, in severely abnormal or accident conditions, is characteristic of the hydrodynamic port shown in Figure 2 when properly incorporated in the reactor cooling system, for the following reason.
  • the detailed design of the hydrodynamic ports based on the principles of operation just outlined may be carried out by persons skilled in the art of hydrodynamic design.
  • the variables such as the axial flow area, the number and thickness of the slots, and the sizes of the plates and spacers may be selected to suit the capacity and the performance specifications for a reactor designed for a particular application.
  • the important properties of the ports discussed above can be enhanced through any number of refinements which may be implemented by those skilled in the art of hydraulic design. Such refinements may include adaptations in the form of the shaping of the edges of the slot-defining plates, the minor progressing of their inside diameters, the introduction of an axial rod of cylindrical, conical or other shape, or the "dishing" of the plates themselves.
  • the objective of this modification is to enhance, relative to the port depicted in Figure 2, the previously-mentioned second important property, namely, the offering of large resistances to both combining and dividing branch flows when the normal operating parameters inadvertently deviate somewhat from nominal values, while leaving essentially unaltered the branch flow area available to the shutdown passive cooling mode.
  • the second enhancement is represented in Figure 4 as an anti- convective shroud to be attached to each hydrodynamic port to not only contain local exchange flow in the port, but also to provide for the self-acting hydrostatic compensation of pressure imbalances tending to produce exchange flow, as discussed below.
  • the hydrodynamic port depicted in Figure 3 may be described as the basic structure of the hydrodynamic port depicted in Figure 2 modified in the following ways.
  • the port of Figure 3 has two extra slot-defining plates 24 in the series which, with the flanges 29 which are now ringed, form blind bypass slots 28, one at each end of the series of regular slots 20.
  • the bypass slots so-formed at either end of the series of regular slots are connected by means of several longitudinal bypass tubes 27 which are located symmetrically about the principal axis, providing a plurality of bypass passages 26 between the bypass slots and, thereby, providing passages between the two flow area defining ducts 21 and 22.
  • bypass passages so defined may be stated as follows: Under ideal normal reactor operation conditions, the ports carry only axial flow. Under such conditions the flow experiences very little resistance in passing through, and between, the regions of the area defining ducts 21 and 22. In the absence of significant levels of such resistance, a negligible pressure difference exists between the entrances to the two bypass slots, and negligible bypass flow is present. Therefore, under the ideal operating conditions characterized by axial flow only, the modified port of Figure 3 behaves within the circuit essentially as does the basic port of Figure 2.
  • bypass tubes may be seen as assuming a share of the port's normal axial mass flow, thereby reducing the axial flow velocity within the port.
  • the corresponding increase in the internal static pressure in the vicinity of the port opposes the incoming branch flow and therefore tends to correct the initial cause, namely, the departure from zero net accumulative pressure in the passive cooling circuit.
  • bypass tubes may be seen as recirculating a portion of the port's normal axial mass flow, thereby increasing the axial flow velocity within this port.
  • the corresponding decrease in the internal static pressure in the vicinity of the port restrains the outgoing branch flow and therefore tends, as for the port experiencing combining branch, to correct the initiating departure of the system from the required zero net accumulative pressure in the passive cooling circuit.
  • the details of the structures for the modified hydrodynamic ports can be specified according to the invention by persons skilled in the art of hydraulic design. Included in this work is the selection of the capacities and the configurations of the bypass channels so that they provide significant enhancement of the second important property as discussed, while not impairing significantly the third important property, namely, the offering of relatively small resistances to large branch flows in severely abnormal or accident conditions.
  • the principal reasons for the persistence of exchange flows are two-fold.
  • the first is port related and results from th fact that a finite amount of local exchange flow wil always be present in ports defined in the manner of eithe Figure 2 or Figure 3.
  • the local exchange flow is th result of small internal pressure differentials caused b both the local dynamic and elevation pressure effects. Such differentials may be experienced in progressin longitudinally from one slot to the next, or in samplin pressures while progressing vertically across the por particularly when the axis is oriented more or less in lin with the horizontal. These effects give rise to loca circulation of coolant into and out of the slots, even whe the net branch flow in the port may have been cancelled du to the above-described design measures.
  • An active mechanism that regulates one or more of the main system parameters to eliminate instrumentally detected or anticipated residual exchange flow within a cooling system constructed in accordance with the invention as described to this point, may be devised by those skilled in the art of thermal- hydraulic control. For reasons of reliability, effectiveness, universal applicability, and harmony with the basic objectives of the invention, however, a passive mechanism is preferred to the active one.
  • the phenomena of local exchange flow associated with each hydrodynamic port of the system, and the exchange flows residual in the reactor cooling system as a whole, are addressed through the introduction of a single attachment applied to each hydrodynamic port of the system.
  • the attachment an example of which is shown in Figure 4, is referred to herein as the anti-convective shroud.
  • the anti-convective shroud is a passive device with the capacity to suppress the local exchange flows in the port to which it is attached, and to accumulate incipient residual exchange flow within the system flow in such a manner that the pressure differentials tending to drive the residual flows are completely compensated.
  • the anti-convective shroud is a passive device with the capacity to suppress the local exchange flows in the port to which it is attached, and to accumulate incipient residual exchange flow within the system flow in such a manner that the pressure differentials tending to drive the residual flows are completely compensated.
  • FIG. 30 is exemplified as an attachment to the hydrodynamic port made up of the components 21, 22, 23, 24, and 25. These components were previously identified in the description of an identical example of a hydrodynamic port, namely, the basic version shown in Figure 2, but without an anti- convective shroud. Such an attachment may be fastened, with similar expected advantage, to any one of a variety of versions of hydrodynamic port, including, for example, the modified version incorporating bypass elements as shown in Figure 3, also described above.
  • the anti-convective shroud 30 is essentially a hood which opens downward and encloses the entire structure of the hydrodynamic port to which it is attached. Apart from the downward opening, and possible vent hole (not shown) through the uppermost point in the shroud surface to eliminate any gases collected, the enclosing surface of the shroud is complete and terminates in sealed joints at the flow defining ducts 21 and 22.
  • the anti-convective shroud has sufficient internal clearance from the port to avoid directly interfering with the flow of coolant through the exchange flow slots 20. Under normal operating conditions, the shroud provides for a largely isothermal, quasi-stagnant zone of coolant generally enveloping the port.
  • This zone of coolant continually adopts the approximate temperature of the coolant flowing axially within the port, by virtue of the stratification grid made up of vanes 31 placed vertically in the downward opening and the thermally insulating material (not shown) that may be placed on the remaining surfaces of the shroud. Since the temperature of the circulating primary coolant, and hence the temperature of the quasi-stagnant zone, is considerably hotter than that of the reserve coolant, a large thermal gradient must exist in the vicinity of the downward opening.
  • the purpose of the stratification grid is to inhibit the formation of local convective circuits in the vicinity of the opening, thereby facilitating the orderly formation and maintenance of thermally stratified layers of coolant ranging from the nearly primary circuit temperatures at the top of the grid, to typically reserve coolant temperatures at the bottom of the grid.
  • the specific configuration of the anti-convective shroud must be designed so that the alignment of the stratification grid is nominally horizontal, in order to best support the thermal stratification of which one isothermal plane is identified by the numeral 32 in Figure 4.
  • the anti-convective shroud can be viewed as a passive device with the capacity to suppress the local exchange flows caused by dynamic and elevation pressure differentials in the port to which it is attached. It was also implied above that, in the absence of special measures such as active primary parameter controls, or the passive compensating effects of the anti-convective shrouds, some residual exchange flows would persist in the reactor cooling system as a whole. Key points of behaviour of the anti-convective shroud which enable it to play a key role in limiting the extent of such residual exchange flow are described in the paragraphs immediately following.
  • the temperature profile in the grid may be characterized by the location of the median temperature plane located, say, midway between the upper and lower extremes of the grid and corresponding to the isothermal plane 32 identified in Figure 4.
  • the partial compensation already achieved at that point will be sustained as long as the temperatures of the coolant residing over the full extent of the grids are sustained, as they surely will be due to the small, but persisting residual exchange flows passing through the quasi-static zones and the grids.
  • the persisting exchange flows will be much smaller in magnitude than would exist in the absence of the compensating behaviour of the described anti-convective shrouds and incorporated stratification grids.
  • moderate disturbances in the primary system operating parameters cause the anti-convective shrouds to accumulate residual exchange flows within their quasi-stagnant zones in such a way that the resulting elevation pressure differentials cancel the original tendency for the exchange flow.
  • the particular design of the anti-convective shroud enabling the cooling system to meet the requirements of a given reactor application may be specified by those skilled in the art of thermal-hydraulic design.
  • the design process must take account of the impact of the presence of shrouds on the performance of the passive cooling system.
  • both the anti-convective shroud and the stratification grid must be designed to neither significantly impede the operation of the passive cooling system operating in the shutdown mode, nor adversely affect the interaction of the passive circuit with the cooling system as a whole, in accident scenarios.
  • a second embodiment of the invention is shown in the sectional elevation of the reactor plant of Figure 5.
  • the cooling system of this plant has all of the essential attributes, and performs all of the basic functions, ascribed to the reactor plant of Figure 1.
  • the embodiment shown in Figure 5 includes two anti- convective shrouds 30 attached to the inlet and outlet hydrodynamic ports, 7 and 8, respectively. These shrouds, and their associated stratification grids 31, enhance the basic performance of hydrodynamic ports in their prescribed roles according to the invention, in the manner described in some detail with reference to Figure 4. Therefore, during normal operations, the reactor plant depicted in Figure 5 may be expected, even in the presence of significant operating disturbances and in the absence of actively compensating control equipment, to exhibit very little exchange flow between the primary circuit, as previously defined, and the reserve coolant tank 14.
  • the reactor plant of Figure 5 is operating initially under a set of nominal operating parameters which satisfy the zero net accumulative pressure requirement for zero exchange flow.
  • the criterion for meeting this requirement is that the change in the dynamic pressure, associated with a constant mass flow passing from port 7 to port 8, must equal the deficit by which the net elevation pressure, assessed accumulatively around the passive cooling circuit, fails to match the resistive pressure losses associated with the primary mass flow through the core 1.
  • the important point to be noted here is that, in assessing the net elevation pressure in terms of essentially the weight difference between a predominantly hot and a predominantly cold column, the height of both such columns is now effectively the vertical distance L g between the median temperature planes falling at approximately the mid-elevation points in the stratification grids of the two ports, 7 and 8.
  • L is now the operative hydrostatic height in satisfying the zero accumulative pressure requirement, as opposed to the height L which, in the absence of shrouds and grids as for Figure 1, was taken as the operative height.
  • the magnitude of L can vary in response to the receipt of small exchange flows within the shrouds, and such variation is the basis of the mechanism for compensating inadvertent departures of the cooling system from the zero net accumulative pressure requirement, which give rise to these flows initially.
  • such a tendency may result, for example, from an inadvertent reduction in pump speed, an increase in circulating primary coolant temperature, or an effective (inertial) increase in the effective gravitational constant due to upward acceleration of the reactor.
  • an inadvertent reduction in pump speed an increase in circulating primary coolant temperature
  • an effective (inertial) increase in the effective gravitational constant due to upward acceleration of the reactor.
  • the consequent contraction in L g corresponds to the reduction in the elevation head that is necessary to cancel the cause of the initiating tendency for ingress exchange flow.
  • the foregoing operational scenario shows, by example, how the cooling system of the reactor depicted in
  • Figure 5 provides, by virtue of the arrangement of the hydrodynamic ports, anti-convective shrouds and stratification grids in accordance with the invention, the process-inherent means for regulating the cooling system during normal reactor operations in such a way that the potentially undesirable side-effects of the passive shutdown system on normal operations are automatically and continuously curtailed.
  • This situation contrasts with that for other reactors having passive shutdown cooling systems which, as . in the present invention, are deployed by process-inherent means.
  • Such other systems depend on sophisticated sensors and active control systems to avoid undesirable side-effects.
  • the embodiment shown in Figure 5 also exemplifies the adaptation of the invention to applications which place severe restrictions on the size of the plant, while requiring passive cooling to become available as needed through inherent processes.
  • the vertical inter-port distance L shown in Figure 5
  • the zero net accumulative pressure requirement is met by making the axial flow area A 2 of the outlet port 8 somewhat larger than the area _ of the inlet port 7.
  • the inlet port and the inlet duct are arranged horizontally, while the outlet port is oriented vertically with its anti-convective shroud and stratification grid arranged symmetrically about the port axis.
  • the individual components depicted in Figure 5 are not drawn to scale and no relative size or configurational relationships among the various components should be inferred literally from the drawing. The detailed design of such components, including the sizing for a particular reactor application, may be carried out by those skilled in the art of thermal-hydraulic design.
  • the drawing is intended to convey, however, representative examples of how the basic principles of the ports and their attached shrouds offer flexibility in the design of reactors for which there is a stipulated requirement of passive shutdown cooling that becomes available, as needed, by process-inherent means.
  • thermosyphon hot leg operative during convective core coolant exchange with the reserve coolant, consists of the upper plenum 3 and the outlet duct 5 leading to the outlet port 8, plus the upper shroud 30 and grid 31.
  • the effective vertical height of the hot leg is therefore approximately e»gual to L 2 , less the vertical distance from the middle of the upper port down to the median temperature plane of the upper grid.
  • the effective vertical height of the cold leg is approximately equal to L , less the sum of L 2 and the vertical distance from the middle of the lower port down to the median temperature plane of the lower grid.
  • the layers of insulation 9 shown attached to the shrouds, as well as to the other components of the primary circuit, are consistent with the roles of the shrouds and grids as components of the passive cooling circuit.
  • the determination of the optimal dimensions to be adopted in achieving adequate thermosyphon head, while conforming to imposed space limitations in a particular reactor design and application, may be performed by those skilled in the art of thermal-hydraulic design.
  • the embodiment of the invention shown in Figure 5 also exemplifies applications in which vertical access to the reactor core must remain available for purposes of shielding placement, control and shutoff mechanism deployment, experimentation (as in the case of a research reactor) , and refuelling and general maintenance. Access to the top of the reactor core is retained in the design of the subject reactor primarily by offsetting the outlet duct 5 immediately as it leads away from the outlet plenum 3. This arrangement is readily accommodated by the flexibility of design yielded by the reactor cooling system in accordance with the invention, and leaves almost the entire space above the core open for the placement of equipment, instrumentation, or experimental apparatus, at the discretion of the designer.
  • the reactor plant as depicted in Figure 5 shows typical utilization of the reactor access thus made available.
  • the reactor access tubes 40 may be used as control or shutdown rod guide tubes, or for in-core flux monitoring devices, in specific reactors requiring such facilities.
  • the access tubes may also be used in research reactors for the insertion of irradiation target samples into the reactor core, or as beam tubes for the formation and extraction of neutron or gamma-ray beams.
  • the reactor vessel 46 of the plant in Figure 5 is shown in an abbreviated form.
  • the component 41 serves as a demountable, thermally insulated baffle which is essential during normal operation to prevent the primary coolant from mixing with the reserve coolant, but is obviously not exposed to very large pressure differentials. In some applications, combining the baffle with reactor core shielding may be advantageous.
  • Access for servicing such facilities, as well as for performing refuelling operations, is obtained through the hatch 15 in the case of a closed or pressurized reactor, or simply through the open surface of the coolant in a pool-type reactor.
  • Such arrangements may provide for continual access to the core while the reactor is operating, without interfering with the operation of the cooling system.
  • a third embodiment of the invention is shown in the sectional elevation of the reactor plant of Figure 6.
  • the cooling system of this plant has all of the essential attributes, and performs all of the basic functions, which were generally ascribed to the reactor plant of Figure 5.
  • the embodiment shown in Figure 6 includes a multiplicity of inlet and outlet hydrodynamic ports, 7 and 8, each coupled hydraulically to a corresponding inlet or outlet plenum, 2 or 3, by means of a corresponding inlet or outlet duct, 4 or 5.
  • the inlet and outlet ports couple also to their respective inlet and outlet manifolds, 36 and 37.
  • the manifolds couple to the inlet and outlet conduits, 11 and 10, which connect with the remaining components of the primary circuit which, as in the first and second embodiments, lie outside the reserve coolant tank 14.
  • the arrangement of components in the third embodiment exhibits general symmetry about the central axis shown in Figure 6.
  • this axis is aligned with the vertical.
  • the several inlet ports are normally found at a common elevation, as are the inlet ports.
  • the arrows show the flow pattern of the primary coolant during normal operation, in which case the total upstream flow to the core is shared, more or less equally, among the several inlet ducts, and the downstream flow, correspondingly, by the several outlet ducts.
  • Each of the hydrodynamic ports shown in Figure 6 is fitted with an anti-convective shroud 30 and a stratification grid 31, which are of designs similar to, but not necessarily identical to, those of the second embodiment.
  • reactor components as fuel elements 18, a neutron reflector 19, gamma shielding, 16 and 17, a neutron shielding tank 38, and various components, 42, 43, 44, 45 and 39, relating to reactivity control.
  • These components do not have a direct role in the functioning of the reactor cooling system shown, but are included in the embodiment to demonstrate how various reactor components and a reactor cooling system made according to the invention may co-exist in an actual reactor.
  • the plant shown in Figure 6 typifies applications in which the reactor cooling system, as well as performing in the manner described with reference to the plants of Figures 1 and 5, also meets the requirements of (i) passive shutdown cooling being always available, regardless of the orientation of the reactor with respect to gravity, and (ii) the normal operation of the reactor being tolerant of various types of dynamic motion and net displacement, both rotational and translational, imposed within specified limits on the reactor plant as a whole.
  • passive shutdown cooling being always available, regardless of the orientation of the reactor with respect to gravity
  • the normal operation of the reactor being tolerant of various types of dynamic motion and net displacement, both rotational and translational, imposed within specified limits on the reactor plant as a whole.
  • the primary coolant of the reactor in Figure 6 is circulated during normal operation according to the pattern depicted by the arrows.
  • the flow to the core 1 is delivered in more or less equal shares by the several inlet ducts 4, and each share is received by a duct as an axial flow transmitted by the corresponding inlet port 7.
  • the flow out of the core is received in more or less equal shares by the several outlet ducts 5, and each share is transmitted by a duct to become an axial flow in the corresponding outlet port 8.
  • Normal operating conditions in the application environments for which the embodiment shown in Figure 6 is eminently suitable, include an alignment of the central axis of the reactor to coincide more or less with the vertical, and an absence of motion of the platform on which the reactor is mounted.
  • a passive circuit in this context, can be defined as any closed path in the system which includes the reserve coolant tank, and the two ducts connecting with any arbitrarily chosen pair of hydrodynamic ports, including pairs of inlet ports, pairs of outlet ports, and pairs formed of any combination of one of each.
  • the sizing of the port areas for the third embodiment shown in Figure 6 is based on L g , the operative hydrostatic height now defined as the vertical distance between the inlet and outlet groups of median temperature planes 32, as well as the nominal values of the key operating parameters.
  • the anti-convective shrouds 30 eliminate or isolate the effects of local exchange flows in the multiplicity of ports, and the self-adjusting capability of the median temperature planes 32, occurring within the various stratification grids 31, serve to automatically eliminate, or limit, incipient exchange flows.
  • such exchange flows are brought about by inadvertent departures of the normal operating parameters from normal. Additional sources of tendency toward exchange flow arise in the configuration of the passive cooling system of Figure 6, however.
  • the various passive cooling paths may operate in concert with each other and carry different components of the total flow through the core.
  • Certain aspects of the detailed design of the cooling system require special attention in respect of passive cooling being available at all reactor orientations. These include the fact that the majority of the passive coolant flow in the core will be, for a range of reactor orientations, in directions other than parallel to the general orientation of the fuel elements, assuming a standard fuel arrangement.
  • Another aspect requiring attention is the fact that the anti-convective shrouds, which are designed in the first instance to optimize the resistance of the cooling system to disturbances occurring during normal operation, give rise to non-symmetries among the various passive cooling circuits.
  • the main feature of the reactor plant showing the third embodiment of the invention, is the availability of effective passive cooling at all times and in all circumstances, including all physical orientations of the reactor plant.
  • Such facility for passive cooling would be of limited value, however, if the presence of such facility were to degrade significantly the efficiency of normal operations, or if the measures re»quired to avoid such degradation were to compromise the operability of the plant.
  • the operating environment that re-quires a passive cooling capability at all physical orientations is likely to be a dynamic environment (as on board ship) for which the effects on normal operation have to be accommodated, in addition to the effects of inadvertent variations in the normal operating parameters as already discussed for all three embodiments.
  • any tendency towards exchange flow between the circulating primary coolant and the reserve coolant may be minimized for all three embodiments, because the axial flow areas of the hydrodynamic ports are chosen so that the zero net accumulative pressure requirement is fulfilled.
  • This statement implies that, in a most likely configuration of the third embodiment of the invention, i.e., one in which the multiplicity of ducts and ports are arranged symmetrically about the principal axis, a certain quality of manufacture is achievable. The quality of manufacture would have to be such that the total mass flow would be shared identically by all ducts, and the specified axial flow areas of the hydrodynamic ports would precisely materialize in the manufacturing process, to the extent that the zero net accumulative pressure requirement would be truly satisfied simultaneously for all passive cooling paths to be found in the system.
  • the permissible amplitude increases because the incipient exchange flow rate is limited by the resistance of the ports to branch flow at the nominal operating conditions, and the reverse swing in each oscillation causes a reversal of the incipient exchange flow, before the available range travel of the median temperature plane in each port becomes exhausted. It follows, therefore, that the period of oscillation at which dynamic amplitudes may be allowed to exceed the maximum permissible static displacement corresponds approximately to twice the time required for the incipient exchange flow to displace the median temperature plane by half the length of the associated grid, when the inclination of the reactor is at the static limit.
  • each anti-convective shroud 30 determines the fraction of the range of the stratification grid 31 that is traversed by the advancing median temperature plane 32 during the first half of each cycle, before it recedes in the second half. If the ports, shrouds and grids are specified so that, for the entire spectrum of anticipated oscillation frequencies, wave amplitudes do not exceed the values which push the median temperature planes beyond the range provided by the grids in a single cycle, then such motions need not result in any actual exchange of primary coolant with the reserve tank.
  • the specification of the components to meet these conditions may be accomplished by persons skilled in the art of hydraulic design.

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Abstract

Un réacteur nucléaire comporte un système de refroidissement entrant en action en cas de défaillance du circuit de refroidissement primaire du réacteur. Des orifices (7, 8) sont situés dans le conduit d'admission (4) en aval du noyau (1) du réacteur, et dans le conduit de sortie (5) en aval dudit noyau, lesquels comportent des canaux (20) d'écoulement à échange destinés à conduire du liquide de refroidissement entre les conduits d'admission et de sortie, ainsi qu'un réservoir (14) de liquide de refroidissement de réserve. En cas de défaillance du circuit de refroidissement primaire un écoulement à convection naturelle de liquide de refroidissement est déclenché et est maintenu sans intervention mécanique ou d'un opérateur entre le circuit de refroidissement primaire et le réservoir de refroidissement de réserve, par l'intermédiaire des orifices.
EP90908442A 1989-09-15 1990-05-30 Systeme de refroidissement de reacteur nucleaire Withdrawn EP0570360A1 (fr)

Applications Claiming Priority (2)

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CA611551 1989-09-15
CA000611551A CA1326916C (fr) 1989-09-15 1989-09-15 Systeme de refroidissement de reacteur nucleaire

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EP3100275B1 (fr) * 2014-01-29 2018-08-22 Palvannanathan Ganesan Réacteur nucléaire flottant à structure de confinement auto-refroidissante et à système d'échange thermique de secours
CN109346196B (zh) * 2018-11-13 2022-04-15 中国核动力研究设计院 一种能动和非能动冷却相结合的熔融物堆内滞留系统
CN111951985B (zh) * 2020-07-15 2022-10-18 四川大学 一种模块化空间核反应堆发电单元

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FR2599179B1 (fr) * 1986-05-22 1988-07-22 Commissariat Energie Atomique Petit reacteur nucleaire a eau pressurisee et a circulation naturelle

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