JPH0943389A - Actinides recycle system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control accumulation of transuranic element waste, while efficiently utilizing the transuranic element as nuclear fuel as well as uranium. SOLUTION: An actinides recycle system which is composed of a fast reactor 37, a light water reactor 38, and facilities 39, 40, 41 for recycling nuclear fuel is a system for recycling minor actinides. That is to say, the fast reactor regulates transuranic element quantity in newly loaded fuel based on the formation reaction quantity and annihilation nuclear reaction quantity of transuranic element in the fast reactor, so that each net yearly consumption of plutonium and minor actinides becomes almost the same as each yearly average output of the plutonium and the minor actinides which are output from the light water reactor 38.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear fuel recycling system having a fast reactor, a light water reactor and facilities for recycling nuclear fuel, and more particularly to a transuranium element (hereinafter
The present invention relates to an actinide recycling system configured to collectively recycle TRU), plutonium (hereinafter referred to as Pu), and minor actinide (hereinafter referred to as MA).

[0002]

2. Description of the Related Art The core of a fast reactor is constructed by adding MA to a mixed fuel of uranium (hereinafter referred to as "U") and Pu.
It has been revealed that MA can be efficiently burned and extinguished with u. However, in the case where Pu and MA are collectively collected from spent fuel and recycled, the optimum configuration of the entire nuclear fuel recycling system in consideration of the coexistence era of fast reactors of light water reactors is not currently considered.

FIG. 11 illustrates a conventional spent fuel reprocessing process of a fast reactor using a metal fuel. That is,
In Fig. 11, the fast reactor spent fuel 1 was dismantled, the fuel was disassembled / sheared together with the cladding tube, and loaded into the electrolytic refining device.
The spent fuel 1 is used as an anode for electrolytic refining 3. Only U is selectively electrochemically deposited on the solid cathode 4 made of steel, and when the concentration of Pu in the molten salt increases to a required value, cadmium (hereinafter, referred to as Cd) is added to the crucible made of an insulating ceramic. U and a required concentration of Pu are deposited on the put Cd cathode 5.

U deposited on the solid cathode 4 is subjected to salt separation 6 and U7 is used as a fuel slag in a process of producing a fuel slag 8 by injection molding. U and P deposited on the Cd cathode 5 are removed by Cd distillation 9, and the U / Pu 10 is used as fuel slag in the process of fuel slag production 8 by injection molding. After inspecting the fuel slag, the fuel slag is inserted into the cladding tube to assemble the fuel 11 and then used as the fast reactor fuel 12.

When the fuel is an oxide, it is necessary to reduce the U oxide and the TRU oxide into the respective metals in order to reprocess them in the above process. As a method for reducing U oxide and TRU oxide, Ca or Mg
A high temperature chemical reaction using is used as a reducing material. For plutonium oxide, a process using Li as a reducing material is disclosed in US Pat. No. 5,118,343.

[0006]

When Pu and MA are collectively collected from the spent fuel of a light water reactor without being separated and recycled to the fast reactor, the relative relationship between the amounts of Pu and MA cannot be adjusted. When Pu and MA are loaded and burned in the core, the relative relationship between the consumption amounts of Pu and MA does not necessarily match the relative relationship between the Pu and MA amounts obtained from the light water reactor side. By the way, the absolute values of these quantities can be arbitrarily adjusted by setting the output scale of the light water reactor and the fast reactor and the setting of the plant base number.

As described above, when the relative relationship between the amounts of Pu and MA consumed in the fast reactor does not match the relationship between the amounts of Pu and MA obtained from the light water reactor side, Pu and M from the light water reactor side are compared.
Since the supply amount of A does not match the consumption amount of Pu and MA in the fast reactor, the mass balance is disturbed.

For example, even if the amount of Pu supplied from the light water reactor side is the same as the amount of Pu consumed in the fast reactor, the amount of MA supplied from the light water reactor side is greater than the amount of MA consumed in the fast reactor. The surplus supply of MA from the light water reactor side remains unburned, and if the recycling of Pu and MA is repeated in this way, the amount of MA in the fast reactor changes with each recycling, making steady operation in the same plant difficult. .

As a result, when coexisting with a light water reactor and a fast reactor, it becomes difficult to construct a nuclear fuel recycling system for efficiently using TRU as a nuclear fuel, that is, an actinide recycling system. In addition, the fact that the TRU cannot be efficiently burned means that the TRU
Larger amounts of waste will be accumulated, more facilities will be required to dispose of them, and economic and technical burdens will increase, including transportation between those facilities and reactors and reprocessing facilities. There is a connecting issue.

The present invention has been made to solve the above-mentioned problems, and in an actinide recycling system in which a light water reactor and a fast reactor coexist, TRU waste is accumulated efficiently while efficiently using TRU as a nuclear fuel together with U. The object is to provide an actinide recycling system that can be controlled.

[0011]

The invention according to claim 1 is an actinide recycling system for recycling uranium, plutonium and minor actinides as nuclear fuel substances, which comprises a fast reactor, a light water reactor and a facility for nuclear fuel recycling. In order to make the net annual average consumption of plutonium and minaactinide (combustion extinction amount-new generation amount) in PAL to be approximately the same as the annual average extraction amount of plutonium and minaactinide extracted from the light water reactor, respectively. The present invention is characterized by having a fast reactor in which the amount of transuranium element and the amount of uranium in the loaded fresh fuel are adjusted based on the amount of transuranic element formation reaction and the amount of annihilation nuclear reaction in the fast reactor.

The invention of claim 2 first recovers plutonium and minor actinides from the light water reactor and the spent fuel of the light water reactor, and first constructs and operates a nuclear fuel recycle for producing a fast reactor fuel of oxide, nitride or metal alloy, It is characterized in that the uranium, plutonium and minor actinides recovered from only the spent fuel of the light water reactor are used to form the initial core of the fast reactor by the produced fuel.

According to a third aspect of the present invention, the initial core of the fast reactor is composed of enriched uranium, and is changed to a fuel of an oxide or a nitride or a metal alloy of uranium, plutonium, and minoractinide by the subsequent recycling. Characterize.

According to a fourth aspect of the present invention, transuranic elements taken out of the spent oxide fuel of the light water reactor are collectively collected without separating plutonium and minor actinides, and the transuranic elements taken out from the light water reactor are rapidly discharged. The feature is that the transuranic element taken out from the fast reactor is recycled to the fast reactor again.

According to a fifth aspect of the present invention, recovery of uranium, plutonium and minoractinide from spent oxide fuel of a light water reactor is carried out by dry reprocessing in which a reduction in a molten salt with lithium or calcium or magnesium and electrolytic refining are combined. It is characterized in that recycling in a fast reactor is carried out by a dry method utilizing molten salt electrolytic refining.

According to a sixth aspect of the present invention, recovery of uranium, plutonium and minoractinide from spent oxide fuel of the light water reactor is dissolved by chlorine gas in molten salt, and electrolytic purification is performed using uranium by using a graphite electrode. Plutonium is an oxide, and a dry method of electrolytically precipitating minor actinide as a metal is performed, and the obtained precipitate is crushed and washed, and the cladding tube is vibratingly filled and used as a fuel for a fast reactor.
The recycling of the spent fuel in the fast reactor is also characterized by the dry method using the same molten salt electrorefining and the vibration filling fuel.

According to a seventh aspect of the invention, plutonium from the light water reactor fuel is recovered by the Purex method, and minor actinide from the high-level waste liquid generated by the Purex method treatment is recovered by the Tolux method and then denitrated to oxidize. Then, the fission product of minaactinide and lanthanide is separated by a dry method in which reduction with lithium, calcium or magnesium and electrolytic refining are combined in a molten salt.

The invention of claim 8 collects plutonium from the LWR fuel by the Purex method, recovers minor actinides from the high-level waste liquid generated by the Purex method by the Tolux method, and then denitrates the oxides. Then, it is dissolved by chlorine gas in a molten salt, and electrolytically refined using a graphite electrode to perform uranium and plutonium as oxides, and a minor actinide is electrolytically deposited as a metal. Is crushed and washed, and then the cladding tube is vibratingly filled and used as a fuel for a fast reactor.

The invention of claim 9 is characterized in that uranium, plutonium, and minor actinides recovered from spent fuel of the light water reactor and the fast reactor are converted into nitrides and then used as pellets or vibration filling fuel in the fast reactor. . The invention of claim 10 is characterized in that the fast reactor, the light water reactor and the facility for fuel recycling are installed in the same site.

[0020]

DETAILED DESCRIPTION OF THE INVENTION In claim 1 according to the present invention, FIG.
As shown in Figure 1, one or more fast reactors 37 and light water reactors 38 and nuclear fuel recycling facilities 39, 40,
41 consists of an actinide recycling system that recycles U, Pu and MA as spent fuel,
The net annual average consumption of Pu and MA (combustion extinction amount-new production amount) in the fast reactor 37 should be approximately equal to the annual average extraction amounts of Pu and MA extracted from the light water reactor, respectively. , Based on the nuclear reaction chain shown in FIG. 1, focusing on the amount of TRU generated reaction and the amount of annihilated nuclear reaction in the fast reactor, the fast reactor in which the amount of TRU and the amount of uranium in the loaded fresh fuel were adjusted was used. .

The burn-out of Pu in the fast reactor is mainly due to the fission reaction of Pu, and its amount is almost constant and does not strongly depend on the Pu loading concentration if the core heat output is constant. On the other hand, the amount of newly generated Pu is mainly due to the neutron capture reaction of U-238, and depends on the U loading concentration, in other words, the TRU loading concentration. Therefore, if the TRU loading concentration is increased, the new annual production amount from U is decreased, and thus the net annual average consumption amount of Pu is increased.

The combustion extinction of MA in a fast reactor is
It is due to fission and neutron capture reactivity of MA, the amount of which depends on the MA loading concentration and thus on the TRU loading concentration. That is, if the TRU loading concentration is increased, MA
The combustion extinction amount of will increase.

On the other hand, M newly generated in the fast reactor
Specifically, A is predominantly americium 241 (Am-241) and americium 243 (Am-243),
As is clear from the nuclide conversion chain shown in Fig. 1,
The new production amount of MA is mainly due to the neutron capture reaction of Pu, and the new production amount depends on the Pu loading concentration, and thus on the TRU loading concentration. That is, when the TRU loading concentration is high, the Pu loading concentration is high, so that the amount of new MA produced is large.

Therefore, the dependence of the net annual consumption of Pu and MA in the fast reactor (combustion extinction amount-new production amount) on the TRU loading concentration was analyzed and evaluated based on the nuclide conversion chain shown in FIG. The result is shown in FIG. FIG. 2 shows the results of evaluating the net annual consumptions of Pu and MA by performing combustion analysis assuming a neutron spectrum in the case of fast reactor oxide fuel. In the evaluation of FIG. 2, T
The RU loading concentration was defined as the loading concentration of TRU: TRU / (TRU + U) × 100 (%), and the total core heat output was 2600MWt and the oxide fuel core was assumed. As is clear from FIG. 2, when the TRU loading concentration is increased, the net annual consumption of Pu is increased, and conversely, the net annual consumption of MA is decreased.

FIG. 3 shows this result as a ratio of (Net annual consumption of Pu) to (Net annual consumption of MA). As apparent from FIG. 3, Pu and M
It can be seen that the relative relationship of the net annual consumption of A can be controlled by the TRU loading concentration. Therefore, by adjusting the TRU loading concentration in the fast reactor according to the relative values of the amounts of Pu and MA obtained from the spent fuel of the light water reactor, the supply amount of Pu and MA from the light water reactor side and the Pu and MA in the fast reactor are adjusted. Can be matched with the net consumption of. As a result, a fast reactor and a light water reactor can coexist.

The absolute values of the supply amounts of Pu and MA from the light water reactor side and the net consumption amounts of Pu and MA in the fast water reactor are arbitrarily adjusted by adjusting the output scale and radix of the light water reactor and the fast water reactor, respectively. It goes without saying that you can do it.

Here, when Pu and MA for forming the initial core of the fast reactor are not available from others, claim 2
First treat the spent fuel of the light water reactor as described in
It is conceivable to recover Pu and MA necessary for constructing the initial core, thereby constructing a nuclear fuel cycle facility for producing fast reactor fuel first, and then operating for a necessary period before constructing a fast reactor.

As described in claim 3, in the actinide recycle system, the initial core of the fast reactor is composed of enriched U, and Pu and MA that are gradually propagated in the subsequent recycling are added to obtain the U enrichment. Can be gradually decreased so that the core of the fast reactor is finally resisted by the deteriorated U and the recovered Pu and MA.

[0029] In claim 4, T from the light water reactor spent fuel is used.
The RU was taken out by collecting Pu and MA collectively without separating them, and the TRU taken out from the light water reactor.
Is recycled to the fast reactor and removed from the fast reactor
U is for recycling again to the fast reactor.

In the fifth aspect, as shown in FIG. 4 in the fourth aspect, U, Pu, and M from the light water reactor spent fuel 13 are used.
Lithium reduction 14 and molten salt separation in molten salt
Performed by dry reprocessing combining 15 and electrolytic refining 3,
Recycling in the fast reactor is carried out by a dry method utilizing purification of the molten salt electrolysis 16.

That is, the light water reactor spent fuel 13 is disassembled
The fuel assembly is disassembled in the step of shearing 2, and the fuel element is sheared, and then in a chloride of an alkali metal element or a chloride of an alkaline earth element or a molten salt obtained by mixing these chlorides.
U in spent fuel as Li reducing material at 500-800 ℃,
Reduces TRU oxide to metal. The lithium oxide 17 produced by the reduction is electrically reduced in the molten salt in the process of the molten salt electrolysis 16 and reused as the metallic lithium 18. U and TRU reduced to metal are separated from the molten salt in the step of molten salt separation 15 and sent to the step of electrolytic refining 3.

After the process of electrolytic refining 3 is the same as the process of electrolytic refining of metal fuel described in the prior art of FIG. 11, but when the spent fuel of the light water reactor is treated, the amount of U with respect to TRU is in the fast reactor. Since it is larger than the required ratio, a part of surplus U is stored as surplus uranium as future fuel19 or reconcentrated by laser method, etc., plutonium enrichment adjustment20, and reused as light water reactor fuel.

For the recycling in the fast reactor, the electrolytic refining process of the metal fuel described in the prior art of FIG. 11 is used. Note that calcium or magnesium can be used instead of lithium.

Further, in claim 6, recovery of U, Pu and MA from the spent oxide fuel of the light water reactor in claim 4 is carried out in a molten salt as shown in FIGS. 5 (a) to 5 (c). Done in. FIG. 5A shows a molten salt (NaCl-KC) in the crucible 21.
l) shows a melting process in which chlorine gas is blown into the gas from the gas introduction pipe 23, (b) shows a process in which UO ₂ is electrolytically deposited on the cathode 24, and (c) shows a gas mixture of oxygen and chlorine. The electrolytic deposition process in which PuO ₂ and UO ₂ blown from the introduction pipe 23 are applied to the electrode 25 is shown. Granular oxidized U obtained in this step
In addition, the cladding tube is filled with vibrationally-oxidized Pu and metallic MA at a predetermined mixing ratio and used as fuel for a fast reactor.

That is, for the spent fuel of the light water reactor, the fuel assembly is disassembled, the cladding tube is decoated as a fuel element, and the fuel oxide is converted to alkali metal chloride or alkali metal as shown in FIG. 5 (a). It is melted by chlorine gas at a temperature of 500 to 800 ° C. in a chloride of an earth element or a molten salt 22 in which these chlorides are mixed.

Next, as shown in FIG. 5 (b), when the graphite cathode 24 is inserted into the molten salt 22 and the graphite crucible 21 is used as an anode, only the molten U oxide ions (uranyl) are taken. Is electrochemically reduced and deposited as uranium dioxide.

Then, when a mixed gas of chlorine and oxygen is blown into the molten salt 22 as shown in FIG.
It becomes Pu oxide ion (plutonil). In this state,
When another electrode 25 made of graphite is inserted into the molten salt 22 and the crucible made of graphite is used as an anode, the molten uranyl and plutonium are electrochemically reduced and deposited as a solid solution of uranium dioxide and plutonium dioxide. To do.

Finally, these precipitates are crushed, the molten salt is washed, the particle sizes are classified, and the particles are inserted into a cladding tube with a predetermined particle size distribution, and the cladding tube is shock-vibrated in the vertical direction and filled. It is used as fuel for fast reactors by vibrating and filling to increase the density.

Further, in claim 7, Pu is recovered from the light water reactor fuel according to claim 4 by the Purex method,
As shown in FIG. 6, the recovery of MA from the high-level waste liquid generated by the treatment by the Purex method is performed by the TRUEX method,
Alternatively, after treatment by oxalic acid precipitation method, denitration is performed to form an oxide, and then MA and lanthanide fission products are separated by a dry method combining reduction with lithium or calcium or magnesium in a molten salt and electrolytic refining. Is.

In FIG. 6, TRU and FP in the high level waste liquid 26
(RE) is extracted with an organic solvent called CMPO,
In other words, it is separated from the high-level waste liquid by TRU extraction 27 by the TRUEX method or coprecipitation with oxalic acid, and denitrated 28 at high temperature by microwaves to become an oxide. CMP
O is Octyl (phenyl) -NN-isobutylcarabamoylmethylp
Abbreviation for hosphineOxide.

The TRU oxide and RE oxide 29 are added to a chloride of an alkali metal element, a chloride of an alkaline earth element, or a molten salt obtained by mixing these chlorides in an amount of 500 to 500 wt.
At 800 ° C, as Li reduction14, only TRU oxide in the spent fuel is reduced to metal and precipitated.

That is, as shown in FIG. 7, the standard free energy of Li oxide formation is smaller than that of TRU typified by Pu, Np, and Am, and is more stable as an oxide. (Large in the negative direction). Therefore, when Li and TRU oxide are reacted, Li oxide is generated and TRU becomes a metal. Also, at 500-800 ℃, it is smaller than U, so T
Precipitates as residual U metal with the RU.

On the other hand, as shown in FIG. 7, the oxide standard free energy of RE represented by Nd and Ce is smaller than that of Li and more stable as an oxide (larger in the negative direction). Even if Li is reacted with RE oxide, RE is not reduced to metal and remains in the molten salt.
Can be separated from RU.

The precipitated TRU metal was electrorefined 3 in FIG.
Purify in step. The metal of purified TRU30 is U,
It can be alloyed with Zr and burned as a metal fuel, but if necessary, TRU oxides and nitrides 32 in the conversion 31 process.
It can also be converted into fuel for use.

The conversion 31 is carried out by reacting with oxygen gas or nitrogen gas at high temperature to form oxides and nitrides, that is, [TRU] O ₂ or [TRU] N 32, or by dissolving in nitric acid once and micro It can be denitrified to an oxide by raising it to a high temperature by waves. In FIG. 6, reference numeral 33 is F
P and 34 are TRU (Am, Cm, Np) and FP (RE),
35 is [RE] OCl, 36 is [TRU], [RE] OCl
Is shown.

Further, in claim 8, Pu is recovered from the light water reactor fuel according to claim 4 by the Purex method,
As shown in FIG. 6, the recovery of MA from the high-level waste liquid generated by the Purex method was treated by the TRUEX method or the oxalic acid precipitation method, followed by denitration to obtain an oxide, and then FIG. As shown in (3), it is dissolved by chlorine gas at a temperature of 500 to 800 ° C. in a molten salt 22 containing a chloride of an alkali metal element or a chloride of an alkaline earth element or a mixture of these chlorides.

Next, as shown in FIG. 5B, when a cathode 24 made of graphite is inserted into the molten salt 24 and the crucible 21 made of graphite is used as an anode, a molten U oxide ion (uranyl) is formed. ) Is electrochemically reduced and precipitates as uranium dioxide. Next, when a mixed gas of chlorine and oxygen is blown into the molten salt 22 as shown in FIG.
The ions become Pu oxide ions (plutonil).

In this state, another electrode 25 made of graphite is used.
Is inserted into the molten salt 22 and the crucible 21 made of graphite is used as an anode, the molten uranyl and plutonium are electrochemically reduced and deposited as a solid solution of uranium dioxide and plutonium dioxide.

Finally, these precipitates are crushed, the molten salt is washed, then the particle size is classified, and the particles are inserted into the cladding tube with a predetermined particle size distribution, and the cladding tube is shock-vibrated in the vertical direction and filled. It is used as fuel for fast reactors by vibrating and filling to increase the density.

In the ninth aspect, the metallic U, Pu, and MA obtained in the fourth, fifth, and seventh aspects are reacted with nitrogen gas to form a nitride, which is then sintered and pelletized or vibrated as it is. After filling, bond Na for improving heat transfer with the cladding tube is added and used as a fast reactor fuel.

In claim 10, by constructing the actinide recycling system of claims 1, 2 and 3 at the same site, and transporting spent fuel and new fuel through underground passages, transportation by cask can be omitted, and power and cooling can be eliminated. The control system and other equipment are shared.

As described above, the actinide recycling system according to the present invention comprises a fast reactor, a light water reactor and a facility for nuclear fuel recycling, and recycles uranium (U), plutonium (Pu) and minor actinides (MA) as nuclear fuel materials. In the actinide recycling system, the net annual average consumption of Pu and MA in the fast reactor (combustion extinction amount-new production amount) is approximately the same as the annual average extraction amount of Pu and MA extracted from the light water reactor, respectively. So that the amount of transuranic element (T
RU: Pu + MA) production reaction amount and annihilation reaction amount are used, and a fast reactor in which the TRU amount and the uranium amount in the loaded fresh fuel are adjusted is used.

As described above, by adjusting the TRU loading concentration in the fast reactor based on the nuclide conversion chain shown in FIG. 1, it is possible to control the relative relationship between the net annual consumption amounts of Pu and MA in the fast reactor. This makes it possible to match the relative values of the Pu and MA amounts obtained from the spent fuel of the light water reactor with the relative values of the net consumption amounts of Pu and MA in the fast reactor. The supply amount and the net consumption amount of Pu and MA in the fast reactor can be matched.

As a result, the surplus supply of MA from the light water reactor side does not burn and remain. Therefore, even if the recycling of Pu and MA is repeated, the amount of MA in the fast reactor does not change with each recycling and becomes constant. The steady operation by the same plant becomes possible. Consequently, in the era of coexistence of light water reactors and fast reactors, it becomes possible to construct a nuclear fuel recycling system, that is, an actinide recycling system, for efficiently using TRU as a nuclear fuel.

Further, since the TRUs can be efficiently burned, the accumulated amount of TRU wastes can be suppressed, and the economical and technical burden for disposing of them can be reduced, and oxides can be reduced. By using Li as the reducing agent of RE, the FP of RE, which is difficult to separate from TRU, can be separated, and the process is greatly simplified.

[0056]

EXAMPLE An example of the actinide recycling system according to the present invention will be described. FIG. 8 is a conceptual diagram showing an example of the overall configuration of the facility of the actinide recycling system and an example of the flow of nuclear fuel between the facilities. This actinide recycling system is composed of a fast reactor 37, a light water reactor 38, a light water reactor spent fuel reprocessing facility 39, a fast reactor fuel molding processing facility 40, and a fast reactor spent fuel reprocessing facility 41. Spent fuels Pu, MA and U are used as nuclear fuel materials.

Pu and MA are recovered from the spent fuel taken out from the light water reactor 38 at the light water reactor spent fuel reprocessing facility 39, and molded into the fast reactor fuel at the fast reactor fuel molding facility 40, and the fast reactor 37 Used in. After that, the spent fuel taken out of the fast reactor 37 is reprocessed in the fast reactor spent fuel reprocessing facility 41, and Pu, M
A and U are collected and again sent to the fuel molding and processing facility 40 for the fast reactor. Then, it is molded into fuel for fast reactors and reused.

However, when the nuclear fuel material is used in the fast reactor 37, the amount thereof decreases because it burns due to nuclear fission. Therefore, in order to reuse it, the fuel molding facility for the fast reactor is required.
At 40, Pu is recovered in the light water reactor spent fuel reprocessing facility 39 when the molding process is performed again,
Supply MA.

In this embodiment, Pu and M in the fast reactor 37
The average annual consumption of A is Pu extracted from the light water reactor 38.
And the average annual extraction amount of MA, respectively,
The flow of the amounts of Pu and MA shown in FIG. 8 is always kept constant.

A longitudinal sectional view of the core of the fast reactor 37 having an output of 1,000,000 KWe in FIG. 8 is shown in FIG. 9, and a transverse sectional view thereof is shown in FIG.
In FIG. 9, reference numeral 42 is the core portion, 43 is the upper gas plenum portion, 44 is the lower shield body portion, and in FIG. 10, reference numeral 45 is the core fuel assembly, which is 475 bodies, and 46 is the control rod, which is 36 bodies. TR of core 42
The U loading concentration is 23%, and the breakdown of Pu and MA is that Pu is
20.9% and MA is 2.1%. Based on the nuclide transmutation chain shown in Fig. 1, these were subjected to combustion analysis assuming a neutron spectrum in the case of fast reactor oxide fuel, and Pu and MA
2 was used to evaluate the net annual consumption of Pu and MA in the fast reactor 1 so that the average annual consumption of Pu and MA in the fast reactor 1 would match the average annual extraction of Pu and MA extracted from the light water reactor 2. It was done. Here, the composition of Pu isotopes and that of MA are the same as those extracted from the light water reactor 2, and Pu-239: Pu-240: Pu-241: Pu-242 = 58: 24, respectively. : 14: 4 (%) Np-237: Am-241: Am-243: Cm-244 = 52.7: 33.8: 10.9: 2.6 (%). Electric output is 1000MWe, core heat output is 2600MWt
It is. The annual annual consumptions of Pu and MA in this fast reactor 1 are 240kg / year and 26kg / year, respectively, which is almost equal to the amount of Pu and MA extracted annually from the light water reactor 1 with an electric output of 1.3 million KWe. .

Therefore, in the case of the above-mentioned embodiment, since the surplus supply amount of MA from the light water reactor side does not remain unburned, even if the Pu and MA are repeatedly recycled, the amount of MA in the fast reactor is recycled. It does not change and remains constant, enabling steady operation in the same plant.

Further, in the era of coexistence of light water reactors and fast reactors, a nuclear fuel recycling system for efficiently using TRU as a nuclear fuel, that is, an actinide recycling system is provided. Further, since the TRUs can be burned efficiently, the amount of TRU wastes accumulated can be controlled, and the economic and technical burden for disposing of them can be reduced.

In the above embodiment, the fuel form in the fast reactor 37 is the oxide, but the same idea can be applied to the case of using the metal fuel and the nitride fuel. Further, even when the amounts of Pu and MA taken out from the light water reactor 38 are different from the above examples, the same idea can be applied, and the present invention can be applied regardless of the type of the light water reactor 38.

In the above embodiment, U for the fast reactor 37 is different from the light water reactor 38, for example, unused depleted uranium from a uranium enrichment plant is used.
The U recovered from the spent fuel may be used. further,
The electric output and the radix of each of the light water reactor 38 and the fast reactor 37 to be combined are not limited to those in the above embodiment, and any combination that satisfies the balance between generation and disappearance of Pu and MA is possible.

Further, the removal of Pu and MA from the light water reactor spent fuel at the light water reactor spent fuel reprocessing facility 39 is
When u and MA are collected together and supplied to the fast reactor 37 without separation, it is not necessary to have two types of equipment for Pu and MA recovery, so a light water reactor spent fuel reprocessing facility
39 facilities can be rationalized and fuel cycle costs can be reduced.

Further, by installing each facility shown in FIG. 8 on the same site, the use place of TRU such as Pu is limited, so that an actinide recycling system preferable from the viewpoint of nuclear non-proliferation can be realized.

[0067]

According to the present invention, since the excess amount of MA supplied from the light water reactor side does not burn, the MA in the fast reactor can be reused even if the recycling of Pu and MA is repeated.
The amount does not change with each recycling and remains constant, enabling steady operation in the same plant.

Further, assuming the era of coexistence of light water reactors and fast reactors, TRU can be efficiently burned in an actinide recycling system for efficiently utilizing TRU as a nuclear fuel, so that the waste of TRU The amount of stocks can be controlled, and the economic and technical burden for disposing of them can be reduced.

Furthermore, since the spent fuel reprocessing facilities for light water reactors and fast reactors can be rationalized, the fuel cycle cost can be reduced, and the places where TRUs such as Pu can be used are limited. Can also provide a preferable actinide recycling system.

[Brief description of drawings]

FIG. 1 is a system diagram showing a nuclide conversion chain for explaining an embodiment of the present invention.

[Fig. 2] Similarly, Pu and MA in the case of fast reactor oxide fuel
The characteristic view showing the result of having evaluated each net annual consumption of each.

FIG. 3 is a characteristic diagram showing the result of FIG. 2 as a ratio of the net annual consumption amount of Pu to the net annual consumption amount of MA.

FIG. 4 is a process chart showing a recycling process of spent fuel in a light water reactor according to claim 5 of the present invention.

FIG. 5 (a) is a vertical sectional view showing a melting step in molten salt for recovering U, Pu, MA from spent fuel of a light water reactor according to claim 6 of the present invention, and FIG. 5 (b) is also UO ₂ longitudinal sectional view showing an electrolytic deposition process, (c) is also PuO _2,
FIG. 6 is a vertical cross-sectional view showing a process of electrolytic deposition of UO ₂ .

FIG. 6 is a recycling process diagram for recovering TRU from the high-level waste liquid generated in the reprocessing of spent fuel in a light water reactor according to claim 7 of the present invention.

FIG. 7: TRU and L for explaining the operation of the present invention
The characteristic view which shows the temperature dependence of oxide formation standard free energy of i and a rare earth.

FIG. 8 is a flow chart showing an embodiment of an actinide recycling system according to the present invention.

9 is a longitudinal sectional view schematically showing the core of the fast reactor in FIG.

10 is a cross-sectional view schematically showing the core of the fast reactor in FIG.

FIG. 11 is a process diagram for explaining a spent fuel reprocessing process of a conventional fast reactor.

[Explanation of symbols]

1 ... Fast reactor spent fuel, 2 ... Demolition / shearing, 3 ... Electrorefining, 4 ... Solid cathode, 5 ... Cadmium cathode, 6 ... Salt separation, 7 ... Uranium, 8 ... Fuel slag production by injection molding,
9 ... Cadmium distillation, 10 ... Uranium plutonium, 11 ...
Fuel assembly, 12 ... Fast reactor fuel, 13 ... Light water reactor spent fuel,
14 ... Lithium reduction, 15 ... Molten salt separation, 16 ... Molten salt electrolysis,
17 ... Lithium oxide, 18 ... Lithium, 19 ... Excess uranium storage, 20 ... Plutonium enrichment adjustment, 21 ... Crucible, 22 ... Molten salt (NaCl-KCl), 23 ... Gas introduction pipe, 24 ... Cathode, 25 ... Others Electrode, 26 ... High-level waste liquid, 27 ... TRU extraction, 28 ... Denitration, 29 ... TRU oxide and RE oxide, 30
… TRU, 31… conversion, 32… [TRU] O ₂ or [TR
U] N, 33 ... FP, 34 ... TRU (Am, Cm, Np),
FP (RE), 35 ... [RE] OCl, 36 ... [TRU],
[RE] OCl, 37 ... fast reactor, 38 ... light water reactor, 39 ... light water reactor spent fuel reprocessing facility, 40 ... fast reactor fuel molding processing facility, 41 ... fast reactor spent fuel reprocessing facility, 42 ... reactor core, 43
… Upper gas plenum, 44… Lower shield, 45… Core fuel assembly, 46… Control rod.

Claims (10)

[Claims] 1. An actinide recycling system for recycling uranium, plutonium and minor actinides as nuclear fuel materials, comprising a fast reactor, a light water reactor and a facility for nuclear fuel recycling, in which each net year of plutonium and minor actinides in the fast reactor In order to make the average consumption (combustion extinction amount-new generation amount) approximately the same as the annual average amount of plutonium and minor actinide extracted from the light water reactor, the generation of transuranium elements in the fast reactor An actinide recycle system having a fast reactor in which the amount of transuranium element and the amount of uranium in the loaded fresh fuel are adjusted based on the reaction amount and the extinction nuclear reaction amount. 2. A nuclear fuel recycle system for recovering plutonium and minor actinides from the light water reactor and spent fuel of the light water reactor and producing a fast reactor fuel of oxide, nitride or metal alloy, constructed and operated first, and use of the light water reactor. 2. The actinide recycling system according to claim 1, wherein uranium, plutonium, and minor actinide recovered only from the spent fuel are used to form the initial core of the fast reactor by the produced fuel. 3. The initial core of the fast reactor is composed of enriched uranium, and is changed to a fuel of oxide or nitride or metal alloy of uranium, plutonium and minoractinide by subsequent recycling. Item 1. The actinide recycling system according to item 1. 4. The transuranic element taken out from the spent oxide fuel of the light water reactor is collectively recovered without separating plutonium and minor actinide, and the transuranium element taken out from the light water reactor is recycled to a fast reactor, The actinide recycling system according to claim 1, wherein the transuranium element taken out of the fast reactor is recycled to the fast reactor again. 5. Recovery of uranium, plutonium and minoractinide from the spent oxide fuel of the light water reactor is carried out by dry reprocessing combining reduction with lithium or calcium or magnesium in a molten salt and electrolytic refining, and then in a fast reactor. 2. The actinide recycling system according to claim 1, wherein said recycling is performed by a dry method utilizing electrolytic refining of molten salt. 6. The recovery of uranium, plutonium and minoractinide from the spent oxide fuel of the light water reactor is dissolved by chlorine gas in a molten salt, and uranium and plutonium are oxidized by electrolytic refining using a graphite electrode. Then, it is performed by a dry method in which minor actinides are electrolytically deposited as metals, and the obtained deposits are crushed and washed, and then the cladding tube is vibratingly filled and used as a fuel for a fast reactor, and used in a fast reactor. The actinide recycling system according to claim 1, wherein the fuel is recycled by the dry method using the same molten salt electrolytic refining and the vibration filling fuel. 7. Plutonium from the light water reactor fuel is recovered by the Purex method, and minor actinide from the high-level waste liquid generated by the Purex method treatment is recovered by the Trox method and then denitrated to form an oxide. The actinide recycling system according to claim 1, wherein the minor actinide and the lanthanide fission products are separated by a dry method in which reduction with lithium, calcium or magnesium in molten salt and electrolytic refining are combined. 8. Plutonium from the light water reactor fuel is recovered by the Purex method, and minoractinide from the high-level waste liquid generated by the Purex method is recovered by the Tolux method, then denitrified to form an oxide and then a molten salt. Dissolved in chlorine gas in the electrolytically refined by using a graphite electrode in the electrolytic purification of uranium and plutonium oxides, the minor actinide as a metal electrolytically deposited respectively by dry reprocessing, crushed the resulting precipitate The actinide recycling system according to claim 1, wherein after cleaning, the cladding tube is vibratingly filled and used as fuel for a fast reactor. 9. The uranium, plutonium, or minor actinide recovered from the spent fuel of the light water reactor and the fast reactor is converted into a nitride and then used as pellets or vibration filling fuel in the fast reactor. Actinide recycling system. 10. The actinide recycling system according to claim 1, wherein the fast reactor, the light water reactor, and the facility for fuel recycling are installed in the same site.