CN1421037A - Power from fission of spent nuclear waster - Google Patents

Abstract

A linear accelerator, preferably of the monochromatic type, accelerates electrons to an energy of about 10 MeV which are directed onto a high Z target such as tungsten to generate gamma rays which are directed onto the fuel material such as U<238> which results in the (gamma, f) reaction, thus releasing about 200 MeV. The reaction is not self-sustaining and stops when the beam is turned off. This accelerator driven reactor may be used to ''burn-up'' spent fuel from fission reactors, if simply operated at 10 MeV. The photo-fission results in typical spent fuel waste products such as Cs<137> and Sr<90> which undergo photodisintegration by the (gamma, n) reaction resulting in short lived or stable products.

Description

Energy with the atomic nucleus waste material fission generation of crossing

Background of invention

Invention field

The present invention relates generally to the processing to the atomic nucleus waste material of using. More specifically, the present invention relates to the electric energy by the heat generation in the fission reaction of the atomic nucleus waste material of using, the invention still further relates to the effective disposal to the atomic nucleus waste material.

Relevant technology

The common 1000 megawatt electric power pressurization water nuclear reactor of the productivity ratio operation with 75% produces about 21 tons of fuel with mistake with 43,000,000,000 watts every ton burnup. The described 21 tons fuel of using is (with about 11m³Total volume be included in 42 and add in the setting-out fuel) generation is about the electric energy of 6.6 hundred million degree. Same energy output is corresponding to 200 ten thousand tons of energy that coal produces of burning in common power plant, and the 200 ten thousand tons of coals that burn produce 120,000 tons of dusts, 5.4 hundred ten thousand tons of CO₂, and 50,000 tons of SO₂。

Comprise uranium (U with the nuclear reactor raw material of crossing²³⁸), its accounted for the waste material that from reactor, moves out gross weight 96%. In the situation of common water reactor (LWR-the most common reactor, it comprises the reactor that adds the setting-out type), comprise about 0.90% U with the waste material of crossing²³⁵, wherein natural uranium comprises this kind isotope about only 0.70%. About 1% of the weight of the waste material that plutonium took. Described plutonium is fissible, and this means that plutonium can be as the fuel in the nuclear reactor. 0.1% of the gross weight of the fuel that minimum actinium class element took. It comprises 50% neptunium, 47% americium and 3% curium, and they are radiotoxin. Described fission product (iodine, technetium, neodymium, zirconium, molybdenum, cerium, caesium, ruthenium, palladium etc.) accounted for the fuel of using gross weight 2.9%.

Two kinds of fission products of main concern are Sr⁹⁰And Cs¹³⁷Because their thermal shock to storeroom in fact is directly proportional with the danger that health is caused. These two kinds of radionuclides are main to being play a part by the heat that discharges with the fuel of crossing, at least to previous decades. Cs¹³⁷It is the transmitted radiation source that a kind of main fuel by with mistake sends. Owing to their the potential possibility to healthy cause danger, and main two kinds of fission products paying close attention to are Tc⁹⁹And I¹²⁹ Be because they are long-standing to these two kinds of product special concerns, and in the fission process, produce with significant quantity, generally under geological conditions, can dissolve, and under common groundwater condition, can move quickly.

Long-term toxicity with the fuel of crossing is by actinium class element, for example Np²³⁷，U ²³⁴， U ²³⁶And Pu²³⁹，Pu ²⁴⁰，Pu ²⁴²Control. At the medium-term and long-term nucleic that exists of the waste material of higher level by exciting the atomic nucleus reaction to be deformed into to stablize state or short-lived nucleic is be used to the optional method of another kind that reduces high-level waste material.

Operation by the nuclear reactor produces about 300 kinds of different radiation products, mainly is that neutron is captured the result that induction is fissioned with neutron. The useful impact of various radionuclides is different, because the chemical action in the main body of radionuclide is different with the radiation that nucleic sends. The dangerous aspect of radionuclide is the disposal of the refuse in the geology apotheca. Comprise that with exposure mechanism underground water contacts the waste material after slowly decomposing from the most common release of apotheca, radionuclide is transported to the environment that easily approaches, in biosphere, distribute, at last from food and water absorption. Although hundreds of isotope appears at in the fuel of crossing or in the refuse that by deriving with the fuel of crossing, only a part is necessary disposal. The fuel that common water reactor was used, i.e. atomic nucleus refuse, below four kinds of isotope Cs¹³⁷，Sr ⁹⁰，I ¹²⁹，Tc ⁹⁹That we mainly pay close attention to, because the heat of their transition, dissolving property or healthy harmfulness in the underground water.

Should be able to guarantee that with the management of the fuel of crossing biosphere does not have the consequence ground of short-term protected under the acceptable condition of economy, and the public must be able to be sure of the validity of this kind method. Owing to comprise long-standing radionuclide with the fuel of crossing, require some protections to be at least 100,000 years. Two kinds of modes are feasible:

1. by in the underground suitable degree of depth continuous isolation thing being installed, make radioactivity original paper and biosphere isolated, wait for the naturally decline of radioactivity original paper;

2. we can utilize the atomic nucleus reaction, and it can change into long-standing refuse the less product of radiativity or short-lived product. This kind scheme is known as differentiation.

The underground problem of depositing the atomic nucleus refuse of this kind is do not have material more permanent than radioactive material, and the radiativity refuse produces heat, hydrogen and helium continuously, and other easy sell of one's property product.

Refuse is stored temporarily in 23 positions, the whole nation behind the uranium that national defence produces, and current 40 positions, the whole nation that are stored in of the radiation that mixes and harm refuse.

In the U.S. about 114 nuclears reactor are arranged, about 400 commercial atomic energy power stations are arranged in the whole world. The atomic nucleus capacitance that comprises about 120Gwe in West Europe has the atomic nucleus capacitance of about 45Gwe in the former Soviet Union and the East European countries. In the U.S., we have just gathered 34,000 tons atomic nucleus waste material. The productivity ratio of the senior waste material of current American is annual 3000 tons. Every year is inserted " interim " storage sites with 60 with the fuel devices of crossing in average commercial power station, and always like this until 2000, when waste material is transferred into Ministry of Energy. But this does not comprise the low-level waste that uses radioactive material from atomic nucleus power station, research center and hospital etc., such as gloves, filter, instrument, clothes etc. Nearly 100,000 U.S. units use radioactive material. Its annual low-level waste that produces 1,600,000 cubic feet.

The project of current American environmental management project spends every year and is about $ 7,500,000,000. Paper research is current accounted for that environment recovers budget be about 20%. According to Baseline environmental management report, total cleaning up cost of atom nuclear weapons programs was 2,300 hundred million dollars between 75 years, comprised 50,000,000,000 Han Fude cleaning.

The maximum nuclear reactor of running is the jumbo common water nuclear reactor on the current market, and the electric energy of its output is 400Mwe. One boiling water reactor that is considered to a kind of common water reactor comprises pressure vessel and the reactor part that is placed in the described pressure vessel. Described reactor partly comprises a plurality of fuel parts. The control lever that is used for the power of control reactor is suitable for being inserted into reactor core section. Described boiling water reactor also has a circulatory system, is used for reactor core section is flow through in the cooling agent circulation, and the described circulatory system also is used for the power of the nuclear reactor is carried out precision adjustment. The steam that produces in the pressure vessel of the nuclear reactor is introduced into the steam turbine, to drive the latter, subsequently condensation in condenser. Then circulation enters pressure vessel to described condensate as cooling agent.

The typical example of another of common water reactor is to add the setting-out reactor, it comprises a pressure vessel, described pressure vessel comprises again a reactor center part, this inductor center part has the pluralities of fuel device, a kind of steam generation device and a kind of main cooling system, its formation comprises the closed-loop of pressure vessel and steam generation device. Pipeline by main cooling system after the cooling agent of described heat is heated in the reactor major part is introduced the steam generation device, to carry out heat exchange with the water of sending in the steam generation device. Described cooling agent is because the heat exchange drop in temperature, enters pressure vessel from the pipeline of steam generation device by main cooling system. On the other hand, the water of input is because the heat exchange evaporation becomes steam. Described steam is introduced turbine, to drive turbine, subsequently condensation in condenser. Described condensate enters the steam generation device as input water again.

The atomic nucleus fission of the heavy element after absorbing electromagnetic radiation (photofission) is at first foretold in its 1939 famous papers by Bohr and Wheeler. Haxby, Shoupp, Stephens and Wells (1941) produce fission with gamma ray for the first time.

Show through data investigation, be the emphasis that a plurality of laboratories use multiple gamma source to study in the photofission repercussion study aspect the photic nucleon 40 years of past always. The main purpose of these researchs is the atomic nucleus information that is in huge dipole resonance zone and obtains excitation energy in low energy area near photofission and photoneutron boundary. Have been found that huge dipole resonance can significantly improve the cross section of effective photon collision nucleon.

The huge dipole resonance that Bowman uses the accurate single frequency photon bundle that obtains from the stroke of single-frequency positive electron to observe for the first time the atomic nucleus of fission splits into two parts characteristically, and this also is the phenomenon of the atomic nucleus of other permanent distortion. Yet, find photon induction Г_n/Г _fRate depends on energy, the result that this result is fully different from the data that neutron induction fission, bremsstrahlung fission and charged particle induction fission obtain.

The system of huge dipole resonance is characterized in that because the discovery of dipole resonance itself absorbs electromagnetic radiation by atomic nucleus and causes very large interest in the energy scope of 5 to 30 million electro-volts. In the past few years, in a lot of laboratories, measured the photoneutron cross section of multiple atomic nucleus with Single photon. These all data are all in atomic energy data atomic nucleus data table. To multiple situation about studying, this agreement is fairly good.

Traditional description about dipole resonance absorption process has indicated that for spherical atomic nucleus whole photon absorption cross-sections is characterised in that long-range navigation is hereby linear,

σ(E _r)＝σ _m/[1+(E _r ²-E _m ²) ²/E _r ²Г ²(equation 1)

σ wherein_mMaximum cross section, E_mBe the resonance energy, and Г is whole width of a half of maximum. For (similar spheroid) atomic nucleus of distortion, all photos illustrate huge resonance fission and become two parts, and it is corresponding to the vibration that is parallel and perpendicular to the atomic nucleus axis of symmetry.

For medium and heavier atomic nucleus, coulomb barrier prevents the emission of the charged particle in huge resonance energy, photon scattering cross section often very little, on (γ, n) boundary. Therefore whole photoneutron cross sections and whole photon absorption cross-section are the most approaching.

The level Four moment Q of the inherence of the atomic nucleus of distortion_oCan draw from following relationship,

Q _o＝2/5ZR ²∈＝2/5Z R ²(η-1)η ^-2/3(equation 2)

Atomic nucleus radius R=R wherein_oA ^1/3, Z and A are respectively atomicity and atomic wts, and ∈ is the centrifugal rate of atomic nucleus, and described parameter η is the ratio of major axis and minor axis (atomic nucleus that is used for prolate), provided by following formula,

E _m(2)/E _m(1)=0.911 η+0.089 (equation 3)

E wherein_m(1) and E_m(2) be and huge resonance suitable two parts long-range navigation lower and higher resonance energy of curve hereby mutually.

The energy of dipole resonance is very low, a lot of so very simple processes, for example (γ, n), and (γ, 2n), (γ, p) and photofission reaction is carried out at huge resonance zone. Competition between these processes is considered to control by the common statistics that compound nucleus is gone to excite, and the neutron emission often accounts for main status like this.

Feature for the huge dipole resonance of actinium class element is to cause especially people's interest. For coulomb barrier atomic nucleus high Z of this kind, high, whole photon absorption cross-sections equals whole photoneutron cross section and photonuclear variable cross-section. Whole photoneutron cross sections is the summation of following reaction cross-section.

(equation .4)

Wherein ν is neutron heavily several of fission reaction. Whole neutrons produces the cross section

(equation .5)

Competition between described neutron emission and the fission can be expressed as

(equation .6)

Described for Г_n/Г _fNumerical value and the fission exponent function relation of atomic nucleus reduce. Explain the Г that is used for of neutron fission and fission competition_n/Г _fThe theoretical relationship constant atomic nucleus temperature that is useful on energy level density draw, and be expressed as:

(equation .7)

Wherein (Ef '-Bn ') be the effective boundary value for corresponding light nuclear, and T is the atomic nucleus temperature.

Such as Th²³²，U ²³³，U ²³⁵，U ²³⁸And Pu²³⁹This fact of launching unnecessary one neutron in each fission has caused producing the possibility of chain reaction in a large amount of fissile materials. It is stable whether chain reaction keeps, gather or weaken gradually depend on by fission produce neutron and by various procedures for example the non-fission of neutron obtain, mainly be (the γ in the system, n) competition between the losing of neutron in the reaction, and the leakage of the neutron on the surface by system.

Energy discharges with the fission speed of 200MeV of an atom at every turn, or every kilogram of U²³⁵Each fission about 23 * 10⁶Speed discharge. The fragment of described fission has carried 82% energy with the form of kinetic energy. It is other 25% that promptly born neutron has carried, and fast quantum carried 3.5%, β decay and accounted for 4%, and the quantum of decay has accounted for 3%, and little neutron carries remaining 5%. Described little neutron and its energy are lost, because the possibility that interacts with little neutron is very little. Some fissions have also produced fast neutron bump U²³⁸Atom. When fuel burns, produce plutonium, and in fact most of energy is from Pu in addition²³⁹Atom. At U²³⁵About 80% of the middle subnumber of middle absorption is created in the fission, remaining 20% be (n, γ) reaction. At Th²³²Photonuclear change in the average kinetic energy that discharges be at U²³⁵Slow neutron fission in 0.8 times of the kinetic energy that discharges, or be about 160MeV.

Summary of the invention

Therefore one object of the present invention just provides a kind of nuclear reactor, and described reactor is by the radioactive material of using or be difficult for fission, and for example common nuclear reactor is provided with fuel with the fuel of crossing.

Another object of the present invention provides a kind of nuclear reactor, can increase security by using subcritical former this kind of stockpile nuclear reactor.

A further object of the present invention provides a kind of nuclear reactor, and its size is less and capacity is less.

According to the present invention that can realize above-mentioned purpose, a kind of system is provided, it can will accelerate to electronics with an accelerator energy of at least 6 million electro-volts, and introduce the fuel of nuclear reactor, the fission that produces thus fuel by the nuclear process that is called " photofission " by the electronics that accelerates or the quantum photon that caused by the electronic impact target of accelerating. Although described fission is not because the fuel of the subcritical material of use or difficult fission continues voluntarily, the photofission of described fuel produces heat and neutron as common nuclear reactor. Described like this photofission process will stop when stopping electron beam immediately. The heat that produces can use as common nuclear reactor with neutron, for example for generation of electric energy.

Disclosed in this invention is that a kind of method and apparatus is used for by heavy element, but is not that fissionable element produces nuclear energy. Described reaction is not by known U²³⁵Continue voluntarily, chain reaction drives, but driven by accelerator. The fuel that is used for the reactor that the accelerator of this type drives can be the fuel of using of fission reactor. The described mechanism that discharges nuclear energy by not fissible material is known as photofission, wherein the photofission boundary energy that produces greater than the fission by the target atomic nucleus of the introducing amount of photon or quantum. For example use U²³⁸, the boundary of described photofission is about 6 million electro-volts, and causes U²³⁸The fission of atomic nucleus discharges about 200 million electro-volt energy.

The accompanying drawing summary

Fig. 1 is the schematic diagram of flow chart of the present invention;

Fig. 2 is the schematic diagram of the preferred embodiment of electron accelerator of the present invention;

Fig. 3 illustrates (γ, n), (γ, 2n), the U that is used in (γ, f) reaction and (γ, whole) cross section²³⁸Part and whole light nuclear cross section figure;

Fig. 4 is Th²³²，U ²³⁸，Np ²³⁷Light nuclear cross section figure;

Fig. 5 is Pu²³⁹Light nuclear cross section figure;

Fig. 6 is by U²³⁸The quantum spectrum analysis figure of 30 million electro-volts that produce of photofission.

The description of preferred embodiment

Fig. 1 illustrates one embodiment of the present of invention, one of them linear accelerator 1, single-frequency type preferably, electronics is accelerated to energy between 5～30MeV, preferably be about the energy of 10MeV, described electron collision one high Z converter, tungsten for example, to produce gamma-rays, the fuel in these gamma-rays directed response heaps 2, for example U²³⁸, this will produce (γ, f) reaction, be also referred to as photofission, discharge thus the energy of about 200MeV. By a main coolant pump 3 cooling agent is pumped by described reactor 2, enter heat exchanger 4 heat is taken out of reactor, in heat exchanger, heat is taken in the secondary cooling agent system that is driven by secondary cooling agent pump 5. The described heat that is carried by secondary cooling agent system is used for driving a turbine 6 at cooling agent by condenser 8 and before again circulating. Described turbine 6 drives a generator 7 to produce electric energy.

Reactor constructed according to the invention needs accelerator 1 to penetrate pipe power with the collection of a kind of 1MW, and this kind reactor will produce the electric energy of about 20MW. Photofission in reactor 2 interior generations is not controlled oneself, and when accelerator 1 beam is closed, above-mentioned photofission will stop. If only from 10 to 20MeV operations, the present invention can be used for burning the fuel of using from common common water crack temperature shift reactor. Operation of the present invention produces common fuel waste product, for example Cs¹³⁷And Sr⁹⁰, it carries out photic division by (γ, n) in the reactor 2 reaction, produces thus short-lived or stable product. Chemical Decomposition with the fuel isotope of crossing is not necessary. Certainly can drive reactor 2 with unnecessary one accelerator and reach higher electric power, and accelerate described burning process. Ideally, the accelerator at four intervals needs the electric power of about 4.8MW to move, and produces the electric power of about 100MW from reactor. Described reactor is not that this factor of controlling oneself is a security feature, and it allows to close immediately having in the situation of problem.

In Table I, provided the important chopped-off head atomic nucleus reaction of reactor 2 interior generations.

Table I. the reaction of in the reactor that accelerator drives, carrying out

The photofission reaction (γ，f)：U 238，Th 232，Pa 231，Np 237，Np 238，Pa 232，Pu 239，Pu 241，Th 227，U 231，U 233，U 235。 Fission reaction (in multiple a kind of) 92U 235+ 0n 1→ 38Sr 94+ 54Xe 140+2 0n 1            38Sr 94→ 39Y 94+β -→ 40Zr 94+β -(stable)            54Xe 140→ 55Cs 140+β -→ 56Ba 140+β -→ 57La 140+β -→ 58Ce 140+β -(stablizing)(γ, n) is concentrated                            92U 236+γ→ 92U 235+ 0n 1                   92U 238+γ→ 92U 236+2 0n 1+γ→ 92U 235+ 0n 1                   95Am 241+γ→ 95Am 240+ 0n 1+ -1e 0→ 94Pu 240                   93Np 237+γ→ 93Np 235+2 0n 1+ -1e 0→ 92U 235            92U 238+γ→  92U 237+ 0n 1+γ→ 92U 236+ 0n 1+γ→ 92U 235+ 0n 1     94Pu 238+γ→ 94Pu 236+2 0n 1+γ→ 94Pu 235+ 0n 1+ -1e 0→ 93Np 235+ -1e 0→ 92U 235      92U 238+γ→ 92U 237+ 0n 1→ 93Np 237+β -+γ→ 93Np 235+2 0n 1+ -1e 0→ 92U 235    94Pu 239+γ→ 94Pu 237+2 0n 1+γ→ 94Pu 235+2 0n 1+ -1e 0→ 93Np 235+ -1e 0→ 92U 235                            94Pu 239+γ→ 92U 235+α Neutron is concentrated                            92U 234+ 0n 1→ 92U 235+γ                92U 238+ 0n 1→ 92U 239+γ→ 93Np 239+β -→ 94Pu 239+β -               90Th 232+ 0n 1→ 90Th 233+γ→ 91Pa 233+β -→ 92U 233+β - (γ, n) neutralization                             1H 3+γ→ 1H 2+ 0n 1(stablizing)6C 14+γ→ 6C 13+ 0n 1(stablizing)39Y 90+γ→ 39Y 89+ 0n 1(stablizing)28Ni 63+γ→ 28Ni 62+ 0n 1(stablizing)36Kr 35+γ→ 36Kr 34+ 0n 1(stablizing)27Co 60+γ→ 27Co 59+ 0n 1(stablizing)81Tl 204+γ→ 81Tl 203+ 0n 1(stablizing)38Sr 90+γ→ 38Sr 88+2 0n 1(stablizing)83Bi 210+γ→ 83Bi 209+ 0n 1(stablizing)56Ba 133+γ→ 56Ba 132+ 0n 1(stablizing)82Pb 210+γ→ 82Pb 208+2 0n 1(stablizing)38Sr 90+γ→ 38Sr 89+ 0n 1→ 39Y 89+β -(stablizing)53I 129+γ→ 353I 128+ 0n 1→ 54Xe 128+β -(stablizing)55Cs 137+γ→ 55Cs 136+ 0n 1→ 56Ba 136+β -(stablizing)26Fe 60+γ→ 26Fe 59+ 0n 1→ 27Co 59+β -(stablizing)The neutron neutralization                     82Pb 210+γ→ 82Pb 209+ 0n 1→ 83Bi 209+β -(stablizing)43Tc 99+ 0n 1→ 43Tc 100+γ→ 44Ru 100+β -(stablizing)53I 129+ 0n 1→ 53I 130+γ→ 54Xe 130+β -(stablizing)53I 127+ 0n 1→ 53I 128+γ→ 54Xe 128+β -(stablizing)11Na 22+ 0n 1→ 11Na 23+ γ (stablizing)

Photofission and the neutron fission boundary value of relevant isotope in Table II, have been provided.

The critical energy of fission of Table II choosing isotope then

The photofission neutron fissionNucleic     Critical value (MeV)    Critical value (MeV)   Am 241       6.0            -   Am 242       -              6.4   Th 232       5.8            1.3   Np 237       5.6            0.4   Np 238       -              6.0   U 233        5.7            0.025   U 234        6.0            0.4   U 235        53             0.025   U 236        -              0.8   U 237        -              6.3   U 238        5.8            1.2   Pu 239       5.8            0.025

The present invention needs the electron accelerator 1 of a kind of high electric power, low-yield (10MeV) or linear accelerator to come driving a reaction to pile 2 interior reactions to produce gamma-rays, figure 2 illustrates the preferred embodiments of the present invention. A kind of row wave resonance ring (TWRR) shape electron accelerator 1 is used in the current techniques suggestion, described accelerator is provided with energy by continuous wave (CW) the L-wave band klystron of two 1.2MW, described klystron preferably produces a kind of electron beam with the radio frequency of 1249MHz, the energy of described electron beam is 10MeV, and electric current is 100mA.

Select TWRR then to strengthen the boundary electric current of electron beam division, and obtain higher accelerator efficient, described higher accelerator efficient is to be realized by low value and the high magnetic field multiplication constant of decay constant. The low value of described decay constant and high magnetic field multiplication constant only are that TWRR just exists. Use the advantage of TWRR rather than standing wave accelerator guide to be, the simplicity of chamber, chamber structure, the size in larger hole is made easily, and separate with circulation ripple guide machinery easily, these all features so that its under higher radiation areas, operate easily.

Described klystron 11 is preferably by the 90KVDC power drives, to produce the 1.2MW radio frequency. Described 1.2MW radio frequency is sent into TWRR by directional coupler 12. Described injector comprises 13, two magnetic lenses of electron gun of 200KVDC, 14, one pre-bunchers 15 of a high frequency limiter and buncher 16. The electron gun of limiter 14 and pack device 16 systems design need to be with the maximum electric current of the 400mA of 200KeV beam energy.

Described accelerator 1 comprises seven accelerator guides 18. Each unit of accelerator part forms a TWRR. The length of each accelerator guide 18 is 1.2m, comprises that the pattern cell of 13 2 π/3 and two lotus roots close cell. All accelerator guides 18 are constant inclination structure type under the condition of 100mA electron beam load.

Described the first klystron is provided with energy to pack device and three accelerator guides, and the second klystron is provided with energy to all the other four accelerator guides. The described radio frequency energy of sending into respectively described pack device and each accelerator guide is 220～250KW.

Described U²³⁸Itself can be used as gamma-rays converter and photofission target, and this has just removed independent electronics to the gamma-rays converter, for example needs of tungsten, and use U²³⁸The target material is as x-ray source. Its advantage is the recovery of the general heat that scatters in converter, and this is 70% of beam energy.

Although described reactor is subcritical and driven by gamma-rays, notice that the neutron that produces is very important as causing still in the common reactor that fast neutron and slow neutron fission. These neutron reactions cause extra energy output, therefore the I/O ratio are increased to the determined value of described design from 1/20.

Fig. 3 is U²³⁸Photonuclear change the cross section and relatively the reaction (γ, n), (γ, 2n), (γ, f) and (γ, total). Attention is at preferred energy grade 10MeV, and described two kinds of photonuclear reactions are (γ, n) and (γ, f).

Fig. 4 illustrates Np²³⁷，U ²³⁸And Th²³²Whole light nuclear cross sections, and Fig. 5 shows Pu²³⁹Whole light nuclear cross sections. Cross section shown in Fig. 4 and Fig. 5 is compared, notice that described cross section roughly is identical, more specifically changing only is 10%. This is very important, because the photon source can not be distinguished between four kinds of fuel sources. No matter be to use U²³⁸， Th ²³²，Np ²³⁷，Pu ²³⁹Or any other photonuclear change material is provided with fuel, and performance all is identical.

Fig. 6 is the U by reality²³⁸The γ spectrum analysis figure of the product that produces of photofission. Unique long-standing product is Na²²，Kr ⁸⁵And Cs¹³⁵, when being exposed to continuous 10MeV photon flux, the photic division of these products.

The effective incineration (γ, n) that the calculating result illustrates the fission waste material requires every second 10¹⁸γ/cm ²The gamma-rays flux, to come the acceleration time decay with 180 times.

Can determine the number of the nuclear reaction (γ, n) in radiative process by following different equation: $d{N}_i/\mathrm{dt}=-({\mathrm{\&lambda;}}_i+{\mathrm{\&sigma;}}_i\mathrm{\&phi;})N_i+\underset{j\&NotEqual;i}{\overset{N_a}{\mathrm{\&Sigma;}}}({\mathrm{\&lambda;}}_{\mathrm{ji}}+{\mathrm{\&sigma;}}_{\mathrm{ji}}\mathrm{\&phi;})N_j,$ (equation .8) $i=\mathrm{1,2}...,N_a$

Wherein

N _iThe number of the=the i level atomic nucleus,

λ _iThe decay constant of the=the i level atomic nucleus,

σ _iWhole light nuclear cross sections of the=the i level atomic nucleus,

λ _ji=be converted to the decay constant of i level atomic nucleus from j level atomic nucleus,

=gamma-rays flux

N _a=the quantity of atomic nucleus in model

Utilize matrix to represent, equation (8) can be write:

DN/dt=AN, (equation .9)

Wherein

          -(λ _i+σ _iφ)(i＝j)，

     A _ji＝{λ _ji+σ _jiφ(i≠j)。

Atomic nucleus can obtain by Taylor expansion formula at the matrix of time t=Δ t: $N(t+\mathrm{\&Delta;t})=N\left(t\right)+\underset{r=1}{\mathrm{\&Sigma;}}{\left(\mathrm{\&Delta;t}\right)}^r/r!d{N}^{\left(n\right)}\left(t\right)/\mathrm{dt},$ (equation .10)

Wherein

    dN ⁽ⁿ⁾(t)/dt is the γ level derivation thing of N (t).

Equation (9) and (10) are merged, and it is as follows to obtain N (t+ Δ t): $N(t+\mathrm{\&Delta;t})=N\left(t\right)+\underset{r=1}{\mathrm{\&Sigma;}}{\left(\mathrm{\&Delta;t}\right)}^r/r!A^{r}N\left(t\right).$ (equation .11)

Described matrix A comprises two kinds of data: described decay constant and light nuclear cross section.

Fast neutron is exposed to nickel to be caused from Ni⁵⁸(n，γ)Ni ⁵⁹The gamma-rays that the Compton of reaction is discrete, the gamma-ray energy of generation is at 5～9MeV. In our application, if described reactor comprises a kind of converter material, for example nickel is similar to and places a relay station, all runs into nickel at every turn. For example, if reactor comprises nickel and U²³⁸Layer,

1. accelerator produces the gamma-rays of the 10MeV that is exposed to the uranium target, to produce photofission in the neutron fast;

2. the decay of gamma ray by the first uranium layer is reduced to the boundary value that is lower than (γ, n) reaction with the energy of gamma ray;

3. the fast neutron that absorbs at the first nickel layer produces 5～9MeV gamma-rays, and this will affect the photofission of next uranium layer.

Use the method for this kind layering, to the thickness of the core section of reactor without limits, therefore the accelerator electron beam is to amplify continuously in each nickel layer.

Except or be not with nickel as relay station, also can use other element or compound or the mixture of element, for example sulphur, dysprosium, yttrium, calcium, titanium, alms bowl, manganese, lead, iron, aluminium and copper.

Although with reference to specific mode, material and embodiment are described, and are appreciated that these disclosed specific situations that the invention is not restricted in the present invention, it may extend to the interior whole situations that are equal to of scope of following claim.

Claims (18)

1. thermal source, it comprises the nuclear reactor that is driven by accelerator, described accelerator accelerates to about energy of 5 to 30MeV with electronics, and described nuclear reactor comprises the atomic nucleus fuel of using.

2. thermal source as claimed in claim 1, wherein said accelerator operates in the mode of continuous wave.

3. thermal source as claimed in claim 1, wherein said accelerator are row wave resonance annular accelerators.

4. thermal source as claimed in claim 1, wherein said accelerator is provided with energy by L section klystron.

5. described thermal source as claimed in claim 4, wherein said klystron is with the frequency operation of 1249MHz.

6. thermal source as claimed in claim 1, the wherein said nuclear reactor comprise that a kind of converter material is used for fast neutron is become gamma-rays by (n, γ) reaction conversions.

7. thermal source as claimed in claim 6, wherein said converter material is nickel.

8. thermal source as claimed in claim 6, wherein said converter material is sulphur.

9. thermal source as claimed in claim 6, wherein said converter material is dysprosium.

10. thermal source as claimed in claim 6, wherein said converter material is yttrium.

11. thermal source as claimed in claim 6, wherein said converter material is calcium.

12. thermal source as claimed in claim 6, wherein said converter material is titanium.

13. thermal source as claimed in claim 6, wherein said converter material is beryllium.

14. thermal source as claimed in claim 6, wherein said converter material is manganese.

15. thermal source as claimed in claim 6, wherein said converter material are plumbous.

16. thermal source as claimed in claim 6, wherein said converter material is iron.

17. thermal source as claimed in claim 6, wherein said converter material is aluminium.

18. thermal source as claimed in claim 6, wherein said converter material is copper.

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