JP2011209144A - Method, system and program for planning fuel processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency in treating radioactive waste, while securing the safety in the reprocessing in which nuclear fuel materials are separated by reprocessing spent fuel.SOLUTION: A preparation step (S1) and a processing order determination step are carried out, when the processing order of fuel assemblies to be processed is determined. In the preparation step (S1), the limit range of a first index on the safety of a reprocessing device, including indices set to characteristic data on the fuel assemblies to be processed and the average value on some of them, arranged in the processing order among fuel assemblies to be processed and a target range of a second index to radioactive waste discharged from the reprocessing device are stored. In the processing order determination step, indices to the limit range and the target range are calculated (S5); and the processing order in which fuel assemblies to be processed are arranged is determined both so that the first index can lie within the limit range, and the second index within the target range, while determining whether the indices lie within the limit range or the target range (S6).

Description

  The present invention relates to a fuel processing planning method, a fuel processing planning system, and a fuel processing planning program for determining a processing order of processing target fuel assemblies in a reprocessing system for reprocessing spent fuel to separate nuclear fuel materials.

  In a nuclear power plant, as a result of a nuclear reaction in a nuclear reactor, plutonium as a nuclear fuel material is accumulated in a fuel assembly that is newly generated from uranium or the like that has been used as a fuel. These nuclear fuel materials accumulated in the fuel assembly are preferably reused. Nuclear fuel material accumulated in the spent fuel assembly is removed in a reprocessing process at the reprocessing facility.

  In the reprocessing facility, spent fuel assemblies received from nuclear power plants such as pressurized water reactors (PWR) and boiling water reactors (BWR) are temporarily stored. The spent fuel assembly once stored is distributed into plutonium (Pu) solution and uranium (U) solution in a separation process through processes such as shearing, dissolution, clarification, measurement and adjustment. Each of these uranium and Pu solutions is purified, concentrated and stored as uranium and MOX (Mixed Oxide) products through a conversion process.

  Reprocessing plants handle fissile material and must not reach criticality. In addition, since the reprocessing plant handles radioactive substances, heat generated by decay heat must be kept from becoming excessive. Thus, for example, Patent Document 1 discloses a method for determining the order of processing spent fuel so as to ensure safety.

JP 2003-35795 A JP 2001-91686 A

  In the reprocessing plant, a part of the fission product contained in the spent fuel is separated as an insoluble residue that is difficult to dissolve in the nitric acid solution in the refining process, and sent to a high-level waste liquid vitrification facility. Similarly, the fission product dissolved in the nitric acid solution is separated and concentrated in the separation step and sent to a high-level waste liquid vitrification facility.

  The platinum group element contained in the insoluble residue affects the temperature control of the glass melting furnace. It has been found that increasing the amount of metal Ru, which is a kind of platinum group, affects the melting of the calcined layer and lowers the glass temperature. For this reason, the platinum group element contained in the insoluble residue is an influential component in the operation of the vitrification facility.

  Minor actinoids confined in vitrified bodies are those whose radioactivity levels fluctuate over 1000 years. For this reason, planning the component in the stage before operation leads to planning in advance the component contained in the vitrified body to be produced, and is considered to be effective in the disposal process.

  However, the composition in the radioactive waste sent to the vitrification process cannot be controlled simply by ensuring the safety of the reprocessing plant by the method disclosed in Patent Document 1, for example. For this reason, as a whole including processing of radioactive wastes, such as a vitrification process, there is a possibility that both safety and economy cannot be achieved.

  Therefore, an object of the present invention is to improve the efficiency of the processing of radioactive waste while ensuring safety in the reprocessing of separating spent nuclear fuel material by reprocessing spent fuel.

  In order to achieve the above object, the present invention provides a fuel processing planning method for determining a processing order of a plurality of processing target fuel assemblies in a reprocessing apparatus that reprocesses spent fuel assemblies to separate nuclear fuel materials. A first index relating to safety of the reprocessing apparatus, including characteristic data of the processing target fuel assembly and an average value of a part of the processing target fuel assembly arranged in processing order. A preparatory step of storing a limit range and a target range of a second index for radioactive waste discharged from the reprocessing device; and wherein the first index is within the limit range and the second index is the And a processing order determining step for determining a processing order in which the processing target fuel assemblies are arranged so as to be within a target range.

  Further, the present invention provides a fuel processing planning system for determining a processing order of a plurality of processing target fuel assemblies by a reprocessing apparatus that reprocesses spent fuel assemblies to separate nuclear fuel materials, and the processing target fuel assemblies And the reprocessing range of the first index relating to safety of the reprocessing apparatus, including the characteristic data of the reprocessing apparatus and those set for the average value of a part of the processing target fuel assemblies arranged in the processing order. A storage device for storing a target range of a second index for radioactive waste discharged from the apparatus, and so that the first index is within the limit range and the second index is within the target range And a processing order determining device for determining a processing order in which the processing target fuel assemblies are arranged.

  The present invention is also directed to a fuel processing planning program for determining a processing order of a plurality of processing target fuel assemblies by a reprocessing apparatus that reprocesses spent fuel assemblies to separate nuclear fuel material, and to the computer, the processing target A limit range of a first index related to safety of the reprocessing device, including characteristics data of a fuel assembly and an average value of a part of the processing target fuel assembly arranged in processing order; A preparation function for storing a target range of a second index for radioactive waste discharged from the reprocessing device, the first index is within the limit range, and the second index is the target range. And a processing order determining function for determining a processing order in which the processing target fuel assemblies are arranged.

  ADVANTAGE OF THE INVENTION According to this invention, in the reprocessing which processes a spent fuel and isolate | separates a nuclear fuel material, the efficiency of processing of a radioactive waste can be improved, ensuring safety | security.

It is a flowchart of 1st Embodiment of the fuel processing planning method which concerns on this invention. It is a flowchart of the reprocessing which isolate | separates a nuclear fuel material by reprocessing a spent fuel assembly with a reprocessing apparatus in 1st Embodiment of the fuel processing planning method which concerns on this invention. It is the figure which put together the main limiting value and target value of the reprocessing process which produces a reprocessing plan in 1st Embodiment of the fuel processing planning method which concerns on this invention. 1 is a block diagram of a fuel processing planning system in a first embodiment of a fuel processing planning method according to the present invention. FIG. It is a table | surface which shows the fuel number of the example of the process target fuel assembly which determines a process order by 1st Embodiment of the fuel processing planning method which concerns on this invention with a typical fuel characteristic. It is a graph which shows the burning average for every fuel assembly in the case of re-processing the plan of the fuel assembly of a process target only in the order listed, and the moving average of every four bodies of the burning degree. It is a graph which shows the Ru amount for every fuel assembly, and the moving average of every four bodies of the Ru amount in the case where the plan of the fuel assembly to be processed is simply reprocessed in the order listed. The burnup for each fuel assembly and the moving average of the four burnups when the reprocessing order of the fuel assemblies to be processed is determined by the first embodiment of the fuel processing planning method according to the present invention It is a graph which shows. The Ru amount for each fuel assembly and the moving average for each of the four Ru when the reprocessing order of the fuel assembly to be processed is determined by the first embodiment of the fuel processing planning method according to the present invention It is a graph which shows. It is a block diagram of the fuel processing planning system in 2nd Embodiment of the fuel processing planning method which concerns on this invention. It is a flowchart of 2nd Embodiment of the fuel processing planning method which concerns on this invention. It is a figure which shows typically the determination method of the temporary process order in one modification of 2nd Embodiment of the fuel processing planning method which concerns on this invention.

  An embodiment of a fuel processing planning method according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or similar structure, and the overlapping description is abbreviate | omitted.

[First Embodiment]
FIG. 2 is a process diagram of reprocessing in which the spent fuel assembly is reprocessed by the reprocessing apparatus to separate the nuclear fuel material in the first embodiment of the fuel processing planning method according to the present invention.

  Spent fuel assemblies irradiated in a nuclear power plant such as a pressurized water reactor (PWR) and a boiling water reactor (BWR) are temporarily stored after being received in a reprocessing facility (S81). The spent fuel assembly once stored is then subjected to processes such as shearing / dissolution (S82), clarification (S83), measurement / adjustment (S84), etc., and then separated in a plutonium (Pu) solution and uranium (U). The solution is distributed (S85). The uranium solution is once concentrated (S86), then purified (S87), and further concentrated (S88). After the plutonium solution is produced (S89), it is concentrated (S90). The purified and concentrated uranium and plutonium are stored as uranium and MOX products through a conversion process (S91).

  In this process, a part of the fission product contained in the spent fuel assembly is separated as an insoluble residue that is difficult to dissolve in the nitric acid solution in the refining step (S83), and sent to the high-level waste liquid vitrification facility. Similarly, the fission product dissolved in the nitric acid solution is separated in the separation step (S85), concentrated (S92), and sent to the high-level waste liquid vitrification facility. The high level waste liquid sent to the high level waste liquid vitrification facility is vitrified (S93).

  In such a reprocessing process, the fuel is in the form of fuel assemblies (eg, bundles of fuel rods, bundles) up to the shearing step. In the shearing process, the fuel assembly is sheared as a unit, divided into a metal part such as a cladding tube and a fuel part, and the fuel part is dissolved in a nitric acid solution.

  In the measurement / adjustment process, the component / amount of the fuel solution is measured, adjusted, and further sent to the downstream process for processing. For example, fuel of several tU is put in a measuring tank and batch processing is performed.

  Spent fuels processed at the reprocessing facility include those having various burnups, uranium 235 residual enrichment, and Pu composition depending on the past combustion history. However, in order to ensure safety by suppressing heat generation and preventing criticality at the treatment facility, there are restrictions on the burnup, uranium 235 residual enrichment, Pu composition, etc., and it is necessary to make a reprocessing plan that observes this. It is said.

  For example, the temperature of equipment in the reprocessing facility increases as the decay heat from the fuel to be processed increases, and the decay heat has a feature that the higher the degree of burnup of the fuel, the higher the decay heat. That is, when processing a fuel with a high burnup and a large decay heat, it is necessary to process a fuel with a low heat generation and a low burnup in order to suppress the amount of heat generation.

Furthermore, there is a limit on the residual enrichment of uranium, the composition ratio of ²⁴⁰ Pu, and the total amount of Pu due to the limitation that it does not become nuclear critical during processing. The higher the residual concentration, the more likely the system becomes critical, and the higher the proportion of Pu, such as ²³⁹ Pu other than ²⁴⁰ Pu, may become critical. In addition, the greater the amount of Pu contained in the fuel, the greater the probability of a nuclear reaction, and the system tends to become critical.

  FIG. 3 is a table summarizing the main limit values and target values of the reprocessing process for creating a reprocessing plan in the present embodiment.

  These restrictions are shown, for example, in the reprocessing business designation application form of the reprocessing facility. The main limit values are summarized as follows.

  [Limit 1] The average burnup of spent fuel reprocessed per day is 45,000 MWd / tU or less. Here, tU is a metal uranium weight conversion value before irradiation.

  [Limit 2] The amount of Pu reprocessed per day is 54 kg or less.

  [Restriction 3] The concentration of residual uranium per batch of measuring tank is 1.6 wt% or less. Here, one batch of the measuring tank usually has a capacity of about 5 tU. With boiling water fuel, the amount of uranium per bundle is about 0.2 tU. For this reason, if the capacity | capacitance of 1 batch of measuring tanks is 5 tU, for example, 1 batch of measuring tanks will correspond to 25 to 30 fuel bundles.

[Restriction 4] The ²⁴⁰ Pu composition ratio per batch of the measuring tank is 17 wt% or more.

  Since the limits of [Limit 1] and [Limit 2] are for the processing amount per day, the average value when averaged per day is subject to the restriction. [Restriction 3] and [Restriction 4] are for one batch of weighing tanks. For example, in the case of fuel for boiling water reactors per batch of weighing tank, the average value for 25 to 30 fuel bundles is limited. Become a target.

  The criticality is monitored by monitoring the Pu concentration of the target device with a neutron count rate and generating an alarm. However, the counting rate varies depending on the target fuel, and when the Pu concentration is monitored under all conditions, the equipment utilization rate of the reprocessing facility decreases. In order to prevent this reduction in equipment utilization rate, the counting rate is predicted from the initial processing plan, the processing plan is corrected, the Pu concentration of the target device is obtained from the display of the counting rate, and the Pu concentration and the temporal change in the counting rate are also predicted. Appropriate operation management is required. In other words, it is necessary to grasp and predict the reading value of the neutron monitor at the stage of the operation plan, and the reading value of the neutron monitor is an operational limitation.

  Therefore, the following restrictions need to be further considered.

  [Restriction 5] The reading of the neutron monitor is within the restriction.

  Furthermore, in a reprocessing plant, not only uranium and plutonium, but also various types of radioactive wastes are generated. In particular, handling of components contained in high-level waste liquid is important. For example, the platinum group element contained in the insoluble residue is a component having an influence in the operation of the vitrification facility. Minor actinoids confined in vitrified bodies are those whose radioactivity levels fluctuate over 1000 years. For this reason, planning the component at the stage before operation leads to planning in advance the component contained in the vitrified product to be produced, and is effective in the disposal process.

  In particular, the platinum group element contained in the insoluble residue affects the control of the temperature of the glass melting furnace, and as the amount of metal Ru, a kind of platinum group, increases, the melting property of the calcined layer decreases and the glass It has been found that it has an effect such as a drop in temperature. Therefore, it is considered that treating the fuel so as to maintain this value at a constant value or a target value is effective for stable operation of the plant. Therefore, it is necessary to consider the following goals.

  [Target 1] The amount of fission product is within a predetermined target range.

  The planning of reprocessing in a reprocessing plant is the processing of the fuel assemblies to be processed so that the respective indicators for the limit range and target range are within the limit range and target range and satisfy the limit and target. It can be considered as a problem of rearranging the order.

  FIG. 4 is a block diagram of the fuel reprocessing planning system in the present embodiment.

  The fuel reprocessing planning system of the present embodiment includes a data reading device 1, a fuel characteristic data storage device 2, a limit value data storage device 3, a target value data storage device 4, an FP target value data storage device 5, and a fuel processing order plan. A device 6, a confirmation device 7, a display input device 8, a display device 9, a selection signal input device 10, and a data selection device 11 are provided. The data reading device 1 reads data from the fuel characteristic data storage device 2, the limit value data storage device 3, the target value data storage device 4 and the FP target value data storage device 5, and supplies the data to the data selection device 11 and the display input device 8. Output.

The fuel characteristic data storage device 2 stores fuel characteristic data of a spent fuel assembly to be processed. The fuel characteristic data is the amount of each nuclide contained in the spent fuel assembly itself or data necessary for deriving the amount of each nuclide. The fuel characteristic data includes, for example, a fuel ID for identifying the spent fuel assembly, an irradiated reactor type, an array of fuel rods such as 8 rows, 8 columns or 14 rows, 14 columns, a fuel manufacturer , Initial uranium weight, initial enrichment, burnup measurements, furnace data and the date and time it was evaluated. The reactor data includes residual uranium weight, uranium residual enrichment, each isotope composition of plutonium, plutonium weight, and the like.

  The limit value data storage device 3 stores limit value data. The limit value data is information on a value that becomes a safety limit value in reprocessing. The safety limit value is a limit value that must be satisfied, for example, so as not to be critical in each processing step, that is, to ensure subcriticality. In addition, the safety limit value includes a limit value to be satisfied in order to prevent excessive heat generation due to decay heat because radioactive materials are handled.

  The target value data storage device 4 stores target data for reprocessing. The target data is information indicating a target value set to have a margin with respect to limit value data that is a limit value for safety in reprocessing.

  The FP target value data storage device 5 stores FP target value data. The FP target value data is a target value for the fission product (FP). This FP target value is a value that is preferably satisfied in order to efficiently perform the high-level waste liquid vitrification step.

  The fuel processing sequence planning device 6 rearranges the selected fuels so as to satisfy the constraint values.

  The confirmation device 7 confirms whether or not it is appropriate to perform processing, and displays the confirmation result on the display device 9 via the display input device 8.

  The display input device 8 transmits information input from the selection signal input device 10 by the user to the data selection device 11 and the confirmation device 7. Further, the display input device 8 receives information from the data reading device 1, the confirmation device 7, or the data selection device 11, and causes the display device 9 to display the information in an appropriate format as necessary. For example, the contents of various data read by the data reading device 1 are displayed on the display device 9 via the display input device 8.

  The data selection device 11 aggregates and classifies the fuel type and amount from the read data, and selects the fuel to be processed. Here, a selection signal is input via the selection signal input device 12.

  FIG. 1 is a flowchart of a method for planning fuel reprocessing in the present embodiment.

  First, preprocessing such as setting determination conditions is performed (S1). Here, the determination condition is a condition for determining the validity of the plan. The determination condition is read from the limit value data storage device 3 and the target value data storage device 4 to the data reading device, and is transmitted to the fuel processing sequence planning device 6 via the data selection device 11.

  Specific determination conditions are, for example, as follows.

[Restriction 1]: Y _EXP ≦ 45,000 (MWd / tU)
[Restriction 2]: Y _Pu ≦ 54 (kg)
[Restriction 3]: Y _ENR ≦ 1.6 (wt%)
[Restriction 4]: Y _Pu240 ≧ 17 (wt%)
[Restriction 5]: Y _NM ≦ C1 (CPS)
[Target 1]: C2 _J ≤ Y _{FP, j} ≤ C3 _J
here,

It is. Also,
p (k): the number of the fuel assembly to be processed k X _EXP (n): burnup of the fuel assembly with fuel number n X _Pu (n): the amount of Pu in the fuel assembly with fuel number n X _ENR (N): Residual enrichment of fuel assembly with fuel number n X _Pu240 (n): Composition of Pu240 in fuel assembly with fuel number n X _{FP, j} (n): Fission of component j of fuel with fuel number n Amount of product Y _EXP : Daily average indicator of burnup Y _Pu : Indicator of Pu amount per day Y _ENR : Indicator of residual concentration per batch of measuring tank Y _Pu240 : Pu240 of batch per batch of measuring tank Composition index Y _NM : Neutron monitor index Y _{FP, j} : Index of the fission product of component j. Nave is the number of treated fuel assemblies per day, Nave ′ is the number of treated fuel assemblies per batch of metering tank, Nave ″ is the number of fuel assemblies to be averaged for fission product evaluation It is. C1 is a limit value of the neutron monitor, and C2 _J and C3 _J represent a target range of the amount of the J-th fission product element.

  In the pretreatment step (S1), the fuel assemblies to be treated are specified and listed. The fuel assembly to be processed is specified by a user input from the selection signal input device 10, for example. Information on the identified fuel assembly is transmitted to the data selection device 11 via the display input device 8. The data selection device 11 reads the fuel characteristic data of the identified fuel assembly from the fuel characteristic data storage device 2 via the data reading device 1. The fuel characteristic data read into the data selection device 11 is transmitted to the fuel processing sequence planning device 6 together with information on the identified fuel assembly. Further, the fuel characteristic data read into the data selection device 11 is displayed on the display device 9 through the display input device 8 together with information on the specified fuel assembly.

  Next, the fuel assembly processing sequence planning device 6 has a restriction in which the first index expressed by the equations (1) to (4) and the reading value of the neutron monitor are expressed by [limit 1] to [limit 5]. The processing order in which the fuel assemblies to be processed are arranged is determined so that the second index within the range and the second index represented by Expression (5) satisfies [Target 1]. The reading value of the neutron monitor is obtained by the method based on the extraction calculation disclosed in Patent Document 2, for example.

  Specifically, first, one fuel assembly is selected from the N fuel assemblies to be processed as the first fuel assembly in the line (S2). The fuel assembly to be selected is, for example, the first one that has been listed as a processing target. When the fuel assembly is selected, the number of calculation processes is incremented (S3).

  Next, it is determined whether or not the number of calculation processes exceeds a predetermined maximum number of trials (S4). If the number of calculation processes exceeds the maximum number of trials, a stop process is performed such as displaying on the display device 9 that the fuel reprocessing has not been planned, etc. (S14), and the process ends. .

  If the number of calculation processes is less than or equal to the maximum number of trials, an index for each limit value and target value is calculated for the selected fuel assembly (S5). Here, the index for the selected fuel assembly is the index for the fuel assembly, the fuel assembly when the fuel assembly is placed in that order, and the number of the preceding fuel assembly. And an index as an average value of the fuel assembly. Specifically, the calculation of Expression (1) to Expression (5) and the extraction calculation of the reading value of the neutron monitor are performed.

  Next, the index calculated in the calculation step (S5) is compared with the limit value and the target range (S6). Specifically, each index obtained by the calculation of Expression (1) to Expression (5) and the extraction calculation of the reading value of the neutron monitor satisfies [Restriction 1] to [Restriction 5] and [Target 1]. It is determined whether or not.

  If all the indices compared in the comparison step (S6) satisfy the limit value or are within the target range, the fuel assembly tried at that time is added at the end of the processing sequence, and the fuel to be processed It is determined whether or not all of the aggregates have been arranged (S7). When all of the fuel assemblies to be processed have been arranged, that is, when all of the N fuel assemblies have been completed, the arrangement of the fuel assemblies is output (S9), and a plan is created. finish.

  If it is determined in step S7 that all of the fuel assemblies to be processed have not been arranged, another fuel assembly to be reprocessed in the next order is selected (S8). The selected fuel assembly is arranged next to the fuel assembly whose reprocessing order has already been determined. Here, the other fuel assembly may be any fuel assembly as long as the order of reprocessing among the fuel assemblies to be processed is not determined. For example, among the fuel assemblies listed as processing targets, the fuel assemblies whose order of reprocessing is not determined and which are listed at the top are arranged next.

  When there is a fuel assembly to be arranged, that is, there is a fuel assembly that has not been arranged among the fuel assemblies to be processed (S8), the process returns to step S3 and an index for the fuel assembly arranged in step S8 (S5) and comparison with conditions (S6) are repeated.

  If any of the indices compared with the limit value and the target range in the comparison step (S6) does not satisfy the limit value or is outside the target range, it is determined whether there is another candidate fuel. (S10). The presence of other candidate fuels is whether or not all fuel assemblies have been tried. When all fuel assemblies have been tried, the fuel assemblies that should be arranged in that order are the fuel assemblies that are to be treated, except for the fuel assemblies that are arranged before that order. This means that calculation (S5) and comparison with conditions (S6) were performed.

  If it is determined in step S10 that there are other candidate fuels, one of the candidate fuel assemblies is selected and arranged in that order (S11). When the fuel assemblies are arranged in the order in step S11, the process returns to step S3, and index calculation (S5) and comparison with conditions (S6) are performed for the fuel assemblies. In this way, in the comparison step (S6), the trial is completed for all the fuel assemblies in which the first index and the second index are within the limit range and the target range, respectively, or the order is undetermined. Until then, the calculation step (S5) and the comparison step (S6) are repeated.

  If it is determined in step S10 that there are no other candidate fuels, that is, it is determined that all fuel assemblies have been tried, it is determined whether there is a candidate for the first fuel assembly in the processing order ( S12). The candidate for the first fuel assembly in the processing order is a fuel assembly that has been placed in the front of the processing order and has not been tested for the subsequent processing order. If there is a candidate for the first fuel assembly in the processing order, one candidate fuel assembly is selected as the first fuel assembly in the processing order, and the first fuel is replaced (S13). Return to step S3. In this way, the process is repeated until there is no fuel assembly whose processing order is not yet determined, or there are no processing target fuel assemblies that are not arranged at the head of the processing order sequence.

  Even if there is no processing target fuel assembly that is not arranged at the top of the processing sequence column, if there is no remaining fuel assembly whose processing order has not been determined, the display device 9 is informed that the fuel reprocessing cannot be planned. A canceling process such as displaying it to the user is performed (S14), and the process ends.

  Next, a case where the processing order is determined according to the present embodiment will be described in comparison with a case where reprocessing is simply performed in the order listed. Here, the capacity of the dissolution tank is equivalent to four fuel assemblies, that is, Nave and Nave ″ are both 4.

  FIG. 5 is a table showing the fuel numbers of examples of processing target fuel assemblies that determine the processing order according to this embodiment together with typical fuel characteristics. FIG. 6 is a graph showing the burn-up for each fuel bundle and the moving average of the burn-up for every four fuel bundles when the plan of the fuel bundle to be treated is simply reprocessed in the order listed. FIG. 7 is a graph showing the Ru amount for each fuel assembly and the moving average of the Ru amount for every four bodies when the plan of the fuel assembly to be processed is simply reprocessed in the order listed.

  When the target fuel assemblies in the table shown in FIG. 5 are simply reprocessed in the order listed, as shown in FIG. 6, the moving average of every four fuel assemblies burns up to a limit value of seven. It is beyond eyes. In addition, the deviation width of the moving average of every four fuel assembly Ru amounts is 0.87.

  FIG. 8 is a graph showing the burnup for each fuel assembly and the moving average of every four burnups when the reprocessing order of the fuel assemblies to be processed is determined according to the present embodiment. FIG. 9 is a graph showing the Ru amount for each fuel assembly and the moving average of every four Ru units when the reprocessing order of the fuel assemblies to be processed is determined according to the present embodiment.

  On the other hand, when the order of reprocessing is determined according to the present embodiment, the moving average of the four burnups of the fuel assembly does not exceed the limit value. Further, the deviation width of the moving average of every four fuel assembly Ru amounts is 0.37, which is smaller than the case of simply performing reprocessing in the order listed.

  As described above, according to the present embodiment, when the fuel assembly to be processed is reprocessed by the reprocessing device in accordance with the determined processing order, the limit range of the first safety-related index and the emitted radioactivity Satisfy the target range of the second indicator for waste. For this reason, the density | concentration of the platinum group element in a high level radioactive waste liquid does not become high too much in a vitrification process, ensuring safety | security. As a result, it is possible to improve the efficiency of processing radioactive waste while ensuring safety.

  In addition, by arranging the cases for all processing orders, then calculating the index and selecting the appropriate one, the number of cases increases exponentially, and planning can be made within realistic calculation time. It may not be possible. However, in the present embodiment, each index is compared with the limit value or the target range in the middle of creating the processing order, and if not satisfied, the subsequent processing order is not tried. For this reason, the number of cases to be evaluated is limited, and the possibility of planning an appropriate processing order within a realistic calculation time increases.

[Second Embodiment]
FIG. 10 is a block diagram of a fuel processing planning system in the second embodiment of the fuel processing planning method according to the present invention.

  The fuel processing planning system of the present embodiment is obtained by adding a deviation fuel determination device 13 and a fuel processing order rearrangement device 12 to the fuel processing planning system of the first embodiment.

  FIG. 11 is a flowchart of the fuel processing planning method in the present embodiment.

  In the present embodiment, first, pre-processing such as setting of determination conditions is performed as in the first embodiment (S1). Next, a relaxation restriction range and a relaxation target range wider than the limit value and the target range shown in FIG. 3 are set, and the provisional processing order is determined (S21). The provisional processing sequence is performed by the fuel processing sequence planning apparatus 6 in the same manner as in the first embodiment by replacing the limit value in the first embodiment with the relaxation limit range and the target range with the relaxation target range. decide.

  Next, the deviation fuel determination device 13 extracts a fuel assembly in which the first index is out of the limit range or the second index is out of the target range (S22). Specifically, when the fuel assembly is reprocessed in the temporary processing order determined in the processing order temporary determination step (S21), it is obtained in the calculation step (S5) (see FIG. 1) in the first embodiment. The index is compared and determined in the same manner as in the comparison step (S6) (see FIG. 1).

  Thereafter, the deviation fuel determination device 13 determines whether there is a fuel assembly in which the first index is out of the limit range or the second index is out of the target range in the fuel assemblies arranged in the tentative processing order. Is determined (S23). If the fuel assemblies arranged in the tentative processing order do not have any fuel assemblies whose first index is out of the limit range or whose second index is out of the target range, the tentative processing order is finalized. Processing order is determined (S24), and the process ends.

  If the fuel assemblies arranged in the tentative processing order include fuel assemblies whose first index is out of the limit range or whose second index is out of the target range, the fuel processing order is rearranged. The apparatus 12 sets the fuel assembly as a critical assembly, changes the order of the critical assembly or other fuel assemblies, and determines the processing order so that the critical assembly disappears. In order to change the order, first, conditions for clearing the target limit j and target l are obtained (S25). For example, if the burnup exceeds a limit value in a certain processing order k, the cause is that the burnup averaged by the k-th fuel assembly from the (k-Nave) number exceeds the limit. That is, a fuel with a high burnup that causes this is present between the number (k-Nave) and the number k. Therefore, the fuel assembly is specified.

  Next, a fuel assembly that can clear the target restriction j and target l by exchanging the processing order with the fuel assembly in question is searched from the provisional processing order list (S26). Then, in the plan to replace the fuel assembly in question with the found fuel assembly to be exchanged, whether or not the other indicators and targets other than those targeted here are satisfied Determine (S27). If it is determined in step S27 that the other restrictions and targets are satisfied, the processing order after the replacement is determined as the final processing order (S28), and the process ends.

  On the other hand, if it is determined in step S27 that the other restrictions and targets are not satisfied, other candidates that can clear the target restriction j and target l by exchanging the processing order with the fuel assembly in question. It is determined whether or not a fuel assembly exists (S29). If another candidate fuel assembly exists, the process returns to step S26, and in the plan in which one fuel assembly is selected from the other candidate fuel assemblies and the fuel assembly is replaced, other restrictions and targets are set. Is evaluated / determined (S27). If it is determined in step S29 that there is no other candidate fuel assembly, stop processing such as notifying the user by displaying on the display device 9 that the fuel reprocessing plan has not been performed is performed. (S14), the process ends.

  As described above, according to the present embodiment, when the fuel assembly to be processed is reprocessed by the reprocessing device in accordance with the determined processing order, the limit range of the first safety-related index and the emitted radioactivity Satisfy the target range of the second indicator for waste. For this reason, the density | concentration of the platinum group element in a high level radioactive waste liquid does not become high too much in a vitrification process, ensuring safety | security. As a result, it is possible to improve the efficiency of processing radioactive waste while ensuring safety.

  Furthermore, in the embodiment, a temporary processing order is once determined for a reference having a margin with respect to the actual limit value and the target value, and then the temporary limit order and the target value are satisfied so as to satisfy the actual limit value and the target value. The processing order is rearranged. For this reason, it is possible to shorten the calculation time required for making a processing plan.

  FIG. 12 is a diagram schematically illustrating a method for determining a provisional processing order in a modification of the present embodiment.

  In this modification, the method for determining the provisional processing order is different. In the temporary processing order determination step of this modification, attention is paid to specific fuel characteristics such as residual enrichment, and fuel assemblies with severe specific fuel characteristics are distributed almost evenly in the temporary processing order. To place. After that, the final processing order sequence is determined by rearranging the temporary processing order by the above-described method.

  As described above, in this modification, for example, a fuel assembly having a high residual enrichment among the fuel assemblies to be processed and a severe fuel assembly for safety and efficiency of reprocessing and high-level radioactive waste processing are temporarily processed. The residual enrichment is averaged by evenly distributing within the order. Moreover, if the burnup of the fuel assembly is high, the amount of Pu in the fuel assembly increases and the residual enrichment decreases. As described above, since the indices for the respective limits and targets are not necessarily independent, if a temporary processing order is determined so that the characteristics are averaged by paying attention to a specific fuel characteristic, a plurality of restrictions are set. It is possible to determine a provisional processing order in which values and targets are averaged. As a result, the provisional processing order can be determined without calculating all the indices, so that the calculation time required to determine the final processing order can be shortened.

  The fuel characteristic to be noted may be not only the residual enrichment but also the ratio of Pu240, the burnup, and the like. Alternatively, these may be used in combination.

[Other embodiments]
The above-described embodiments are merely examples, and the present invention is not limited to these. Moreover, you may implement combining the characteristic of each embodiment.

DESCRIPTION OF SYMBOLS 1 ... Data reading device, 2 ... Fuel characteristic data storage device, 3 ... Limit value data storage device, 4 ... Target value data storage device, 5 ... FP target value data storage device, 6 ... Fuel processing sequence planning device, 7 ... Confirmation Device: 8 ... Display input device, 9 ... Display device, 10 ... Selection signal input device, 11 ... Data selection device, 12 ... Fuel processing order rearrangement device, 13 ... Deviation fuel determination device

Claims (9)

In a fuel processing planning method for determining a processing order of a plurality of fuel assemblies to be processed by a reprocessing device for reprocessing spent fuel assemblies to separate nuclear fuel materials,
A first index relating to safety of the reprocessing apparatus, including characteristic data of the processing target fuel assembly and an average value of a part of the processing target fuel assembly arranged in processing order. A preparatory step of storing a limit range and a target range of a second index for radioactive waste discharged from the reprocessing device;
A processing order determining step for determining a processing order in which the processing target fuel assemblies are arranged so that the first index is within the limit range and the second index is within the target range;
A fuel processing planning method comprising: The processing order determination step includes
One trial of undecided fuel assemblies that are not included in the processing order among the processing target fuel assemblies in a processing order sequence that is an arrangement of fuel assemblies in which the processing order is determined among the processing target fuel assemblies A calculation step of calculating a first index for the limited range and a second index for the target range when a fuel assembly is added;
A comparison step of determining whether the first index calculated in the calculation step is within the limit range and whether the second index is within the target range;
In the comparison step, the calculation step and the comparison step are repeated until the first index and the second index are within the limit range and the target range, respectively, or are performed for all of the undetermined fuel assemblies. First repeating means;
A determining step of adding the trial aggregate to the end of the processing sequence when the first index and the second index are within the limit range and the target range, respectively, in the first repetition step. When,
A second repeating step of repeating the first repeating step and the determining step until the undetermined fuel assemblies disappear or the number of fuel assemblies included in the processing sequence does not increase;
If the number of fuel assemblies included in the processing order sequence does not increase even if the second repeating step is repeated for all of the undetermined fuel assemblies, the one fuel assembly other than the top of the processing order sequence is processed. A top replacement process arranged at the top of the sequence, and
A third repeating step that repeats the leading exchange step and the second repeating step until the undetermined fuel assemblies disappear or the processing target fuel assemblies that are not arranged at the top of the processing sequence are exhausted; ,
The fuel processing planning method according to claim 1, comprising: The processing order determination step includes
Temporary processing sequence in which the processing target fuel assemblies are arranged so that the first index is within a mitigation restriction range wider than the restriction range and the second index is a mitigation target range wider than the target range A processing order provisional determination step for determining
A needy assembly determination step of extracting a fuel assembly in which the first index is out of the limit range or the second index is out of the target range;
When there is a fuel assembly requiring attention extracted by the attention assembly determining means, the required parameter is set so that the first index is within the limit range and the second index is within the target range. A processing order rearrangement step that determines the processing order by replacing the order of fuel assemblies with the order of other fuel assemblies;
The fuel processing planning method according to claim 1, comprising: The processing order determination step includes
A processing order provisional determination step for determining a provisional processing order in which the processing target fuel assemblies are arranged so that predetermined fuel characteristics become average; and
A needy assembly determination step of extracting a fuel assembly in which the first index is out of the limit range or the second index is out of the target range;
When there is a fuel assembly requiring attention extracted by the attention assembly determining means, the required parameter is set so that the first index is within the limit range and the second index is within the target range. A processing order rearrangement step that determines the processing order by replacing the order of fuel assemblies with the order of other fuel assemblies;
The fuel processing planning method according to claim 1, comprising:   In the processing order provisional determination step, the fuel assembly whose value selected from the burnup, the uranium residual enrichment, and the composition ratio of the plutonium 240 to the weight of the total plutonium is out of the predetermined reference range is almost uniformly distributed. 5. The fuel processing planning method according to claim 4, further comprising a step of determining an order.   The first index includes the burnup of the fuel assembly, the residual enrichment of uranium 235 in the fuel assembly, the amount of fission products in the fuel assembly, and the composition ratio of plutonium 240 in the fuel assembly to the total plutonium weight. 6. The fuel processing planning method according to claim 1, further comprising: at least one of a detected value of a neutron monitor in the reprocessing apparatus.   The fuel processing planning method according to claim 1, wherein the second index includes an amount of a platinum group element in the fuel assembly. In a fuel processing planning system for determining a processing order of a plurality of fuel assemblies to be processed by a reprocessing device for reprocessing spent fuel assemblies to separate nuclear fuel materials,
A first index relating to safety of the reprocessing apparatus, including characteristic data of the processing target fuel assembly and an average value of a part of the processing target fuel assembly arranged in processing order. A storage device for storing a limit range and a target range of a second index for radioactive waste discharged from the reprocessing device;
A processing order determining device that determines a processing order in which the processing target fuel assemblies are arranged so that the first index is within the limit range and the second index is within the target range;
A fuel processing planning system comprising: In a fuel processing planning program for determining a processing order of a plurality of processing target fuel assemblies by a reprocessing device for reprocessing spent fuel assemblies to separate nuclear fuel materials,
A first index relating to safety of the reprocessing apparatus, including characteristic data of the processing target fuel assembly and an average value of a part of the processing target fuel assembly arranged in processing order. A preparatory function for storing a limited range and a target range of a second index for radioactive waste discharged from the reprocessing device;
A processing order determination function for determining a processing order in which the processing target fuel assemblies are arranged so that the first index is within the limit range and the second index is within the target range;
A fuel treatment planning program comprising:

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