Uranium chilling debugging method for spent fuel post-treatment process

Abstract

The invention belongs to the technical field of power reactor spent fuel post-treatment debugging, and particularly relates to a uranium chilling debugging method for a spent fuel post-treatment process. The method comprises the following steps: S1, acid uranium preparation sub-stage: uranium dissolution and chemical separation system acid transition which are independently carried out are included, and preparation is made for introducing uranium into a to-be-extracted raw material 1AF of uranium and plutonium co-extraction one cycle; s2, a uranium cycle establishment sub-stage; s3, a feeding and discharging balance sub-stage; and S4, a redox atom stage. The method can be applied to the post-treatment plant, progressive and stable transition of the uranium cooling test of the post-treatment plant is achieved, the debugging period is shortened, and the debugging cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of power reactor spent fuel post-processing debugging, and in particular relates to a spent fuel post-processing process cold uranium debugging method. Background Art

[0002] The commissioning of power reactor spent fuel reprocessing is divided into four stages: water test, chemical test, cold uranium test, and thermal test. The task of the cold uranium test is to introduce cold uranium (depleted uranium powder and cold uranium components) into the process system for system test and linkage test, verify the processing capacity of the head end and the tail end of uranium with cold uranium, test the hydraulics, acid mass transfer, uranium mass transfer performance, three wastes treatment capacity of the extraction equipment, test the operating status and performance of the process system under normal operating conditions and fluctuating conditions, verify the matching, continuity and stability of each facility and system, and lay the foundation for thermal test. The traditional cold uranium test method is to carry out the test in the order of "system test first, then linkage test", which has the problems of uncompact test arrangement and unclear test logic, which is not conducive to the control of commissioning cycle and cost. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a spent fuel reprocessing process cold uranium debugging method, which can be applied in a reprocessing plant to achieve a gradual and smooth transition of the cold uranium test in the reprocessing plant, shorten the debugging cycle, and reduce the debugging cost.

[0004] The technical solution adopted by the present invention is:

[0005] A method for debugging cold uranium in a spent fuel post-processing process comprises the following steps:

[0006] S1. Uranium Acid Preparation Sub-stage

[0007] It includes two parts of independent uranium dissolution and acid transition of chemical separation system, which prepares for the introduction of uranium into the raw material 1AF to be extracted in one cycle of uranium-plutonium co-extraction;

[0008] S2, uranium cycle establishment sub-stage;

[0009] S3, inlet and outlet balance sub-stage;

[0010] S4, redox substage.

[0011] The uranium dissolution specifically comprises the following steps:

[0012] Preset uranium distribution according to the head end, co-decontamination separation, uranium second cycle, uranium third cycle, solvent regeneration, and evaporation concentration equipment 80% loading, reserve an intermediate buffer tank, and calculate the minimum uranium inventory that meets the uranium cycle as the target value for uranium dissolution;

[0013] Establish a monitoring mechanism to implement monitoring at least twice a day to promptly detect uranium losses and assist in troubleshooting abnormal operating conditions;

[0014] Verify the functionality of the uranium dissolution system, achieve normal dissolution of uranium dioxide and uranium trioxide powders, and prepare uranyl nitrate solution after seasoning as the 1AF cold uranium solution required for the cold uranium test.

[0015] The acid transition specifically comprises the following steps:

[0016] The parameters determined by chemical linkage tests were used for co-decontamination separation, plutonium purification, and uranium purification. The corresponding concentrations of nitric acid were used to replace the various aqueous phase reagents in the chemical separation system, start the acid transition, and establish the steady state of the extraction system;

[0017] Establish organic phase self-circulation for co-decontamination separation, plutonium purification and solvent regeneration, and uranium purification and solvent regeneration respectively; monitor the organic phase more than twice a day to promptly detect organic phase losses and assist in troubleshooting abnormal operating conditions;

[0018] Verify the flux matching of the solvent regeneration system and the coexistence of kerosene self-circulation and one-time pass operation modes;

[0019] Verify the solvent distillation processing capacity, product quality and residual liquid production;

[0020] Based on the principle of waste minimization, a special feed tank for chemical test waste liquid and a special receiving tank for cold uranium test waste liquid are set up to isolate chemical test waste liquid from cold uranium test waste liquid. The waste liquid treatment evaporator first continues to treat the chemical test waste liquid, and neutralizes and discharges it in time according to the situation. After the treatment is completed, the cold uranium waste liquid is treated.

[0021] Temporary manholes or cover plate bayonet holes are set for the mixing and clarifying tank, the raffinate and product liquid storage tank, and the emptying tank. They are not welded and sealed for the time being, so as to directly observe the inter-stage operation of the mixing and clarifying tank, the emulsion generation, the phase entrainment, etc., and retain the manual processing capacity;

[0022] For the head-end hot chamber, plutonium tail-end hot chamber, sampling cabinet, glove box and other chambers, the penetration parts and holes will not be sealed for the time being, and the ability to add and adjust electrical / instrumentation and control functions will be retained.

[0023] The verification of the flux matching of the solvent regeneration system and the coexistence of the kerosene self-circulation and one-time passing operation modes are specifically as follows:

[0024] First, operate in a one-time pass mode, store a certain volume of kerosene in the waste kerosene storage tank, then switch the deoiling tank to the kerosene self-circulation mode, when the TBP content of the aqueous phase after deoiling is close to the limit or reaches the set replacement cycle, the waste kerosene is transported to the organic phase mixing tank to participate in the extractant seasoning, or returned to the front-end extraction equipment at a low flow rate to run completely, and then replaced with fresh kerosene, and the operation is repeated; secondly, appropriately increase the overall TBP concentration of the system's extractant to offset the dilution effect of kerosene on the organic phase when it passes through once, thereby ensuring the extraction effect.

[0025] The S2 specifically includes the following steps:

[0026] S201, Chemical Separation System Uranium Cycle

[0027] Introduce 1AF cold uranium liquid, gradually open up the main path, reuse path, and waste liquid path, and establish a uranium cycle. At this time, the system does not introduce reducing agents and oxidizing agents; on the basis of maintaining the stability of the uranium cycle, verify the uranium yield of each unit, verify the matching, continuity, and stability between the systems, and further verify the optimal operating range of the parameters;

[0028] S202, plutonium purification and internal circulation of plutonium tail

[0029] The plutonium purification system uses the 1BP uranium-containing liquid normally produced by the co-decontamination separation system as 2AF for cold uranium experiments on extraction, washing, stripping and supplementary extraction;

[0030] The plutonium tail system receives the 2BP liquid from the plutonium purification system to simulate OF conditioning, simulate precipitation filtration, and mother liquor destruction, and establishes a plutonium line cycle of "2BP→OF→OW→2AF";

[0031] During the cold uranium test phase, uranium is not introduced into the hot cell line at the tail end of the plutonium. Only no-load linkage tests of the hot cell line are carried out to avoid the problem of uranium residue in the hot cell line affecting the plutonium products of subsequent hot tests.

[0032] S203, common system matching test

[0033] Verify the analytical testing methods for cold uranium test samples;

[0034] Verify the compatibility of the automatic sampling and delivery system;

[0035] Conduct plant-wide filter DOP tests;

[0036] Verify the overall performance of the ventilation and exhaust system of the entire plant to ensure that the negative pressure in each area meets the requirements;

[0037] Initial testing of regional gamma monitors, criticality alarms, neutron count rate meters, plutonium inventory monitors, and offline low-level liquid activity monitors;

[0038] After uranium is introduced into each system, the liquid level, density and interface monitoring data will change significantly, and the DCS control system parameters will be adjusted for matching.

[0039] The uranium cycle includes:

[0040] Main route: The introduced 1AF cold uranium liquid is subjected to the "enrichment process" of co-decontamination separation, uranium secondary circulation, and uranium tertiary circulation to obtain 3EU;

[0041] Multiplexing path: 3EU is evaporated and concentrated and returned to the head end to prepare 1AF;

[0042] Waste liquid route: 1AW+1AXXW, 2AW, and 2DW are used for evaporation and concentration of "high-level" waste liquid; 3DW, waste acid and alkali, and leaching acid are used for evaporation and concentration of medium- and low-level waste liquid. The resulting residual liquid is all solidified with cement and is prohibited from being transported to high-level amplification tanks.

[0043] The S3 specifically includes the following steps: S301, head end cold uranium test; S302, uranium tail end cold uranium test.

[0044] The S301 specifically includes the following steps:

[0045] After the shearing machine has completed the no-load and disassembly tests, the shearing system load linkage test is independently carried out using carbon steel simulation components to confirm that the functions of each mechanical and exhaust system are normal;

[0046] On the basis of stable uranium circulation, cold uranium components are used to carry out full-process tests of component transfer, lifting, shearing, waste transfer, dissolution, clarification, conditioning, and metering, prepare 1AF cold uranium liquid, and introduce it into uranium circulation, and the corresponding batch of 3EU at the tail end of uranium is used as fluidized bed preparation;

[0047] Verify the shear dissolution performance and processing throughput, conduct variable tests with different shear lengths, confirm the parameters related to negative pressure, dissolved gas peak, and acid recovery, and verify the switching function of the north-south line shearing machine;

[0048] Confirm that the mechanical processes of basket rotation, cladding dumping, end receiving, and waste transfer are normal;

[0049] Establish temporary reception measures for spent cladding and terminals and transfer them to the low- and medium-level solid waste treatment system;

[0050] Verify the solid-liquid separation effect of sedimentation centrifugation, carry out variable tests on feed flow rate and amplitude parameters, and obtain the best operating conditions;

[0051] Establish temporary slag water filtration measures to transfer cold uranium waste slag to the low- and medium-level solid waste treatment system;

[0052] Use cold uranium clear liquid to conduct a seasoning test and prepare qualified 1AF cold uranium liquid;

[0053] Use 1AF cold uranium liquid to verify the reliability of the hardware and software for precise measurement and calculate the uncertainty.

[0054] The S302 specifically includes the following steps:

[0055] The head end and the uranium tail end match to execute feeding and discharging: when the shearing machine starts to shear the cold uranium components, the fluidized bed at the uranium tail end enters fluidization; when the 1AF cold uranium liquid produced by shearing and dissolving starts to feed the 1AX column, the fluidized bed starts to discharge continuously; after the shearing and dissolving test of the last group of cold uranium components is completed, the fluidized bed stops discharging according to the total uranium amount of the system;

[0056] Conduct fluidized bed denitrification discharge test to verify the feed flow rate, three-stream gas flow rate, temperature at each point, bed pressure difference, negative pressure, backwashing, and elution parameters to determine the best operating conditions;

[0057] Confirm that the screw conveyor, uranium product packaging box, uranium product transfer, electric rail trolley, gripper, and storage well are functioning properly;

[0058] Before the end of the cold uranium test, the 3EU concentrate that can meet the minimum inventory of uranium circulation will be temporarily stored in the start-up and shutdown liquid storage system for the cold uranium transition during the hot test.

[0059] The S4 specifically includes the following steps:

[0060] S401, introduction of redox agent

[0061] After the extraction system has established a steady state of uranium, the redox agent can be introduced to carry out the test;

[0062] Before introducing the reducing agent, fully test the oxidant output efficiency and introduce the oxidant in advance to avoid the problem of the reducing agent entering the evaporator due to incomplete oxidation of the liquid;

[0063] The amount of reducing agent introduced is reduced to 30% of normal operation, and the oxidizing agent is introduced in a matching amount;

[0064] Verify the performance of tetravalent uranium preparation, obtain electrolysis efficiency, order, hydrazine concentration, temperature parameters, and determine the best operating conditions;

[0065] Verify the performance of NOx preparation, obtain NOx output efficiency, and verify the reliability of 2AF, OF, and 2DW oxidation seasoning processes;

[0066] S402, three wastes full process matching operation

[0067] The systems for high-level radioactive waste treatment, deep purification, discharge of tritium-containing wastewater, treatment of medium- and low-level radioactive wastewater, cement solidification, discharge of purified wastewater, solvent distillation, incineration of distillation residues and light kerosene are matched and operated to receive and treat cold uranium wastewater, further confirm the treatment capacity, and uniformly treat uranium-containing wastewater with cement solidification. High-level amplification tanks and slag water tanks are not used;

[0068] The low- and medium-level radioactive solid waste treatment and temporary storage and combustible waste treatment systems are operated in coordination, cold uranium solid waste is received and processed, and the processing capacity is further confirmed. Uranium-containing solid waste is uniformly treated as low- and medium-level radioactive waste, and the high-level / alpha waste treatment system is not activated;

[0069] The process tail gas treatment, nitrogen oxide absorption, plant exhaust, exhaust tower and other systems are matched and operated to receive and treat the cold uranium waste gas and further confirm the treatment capacity;

[0070] S403, Parking rectification

[0071] Complete the welding and sealing of covers / manholes of all storage tanks and mixing and clarifying tanks;

[0072] Complete the sealing and testing of large hot chambers and box chambers;

[0073] Set up a special feed tank for cold uranium test waste liquid and a special receiving tank for hot test waste liquid, and establish isolation between cold uranium test waste liquid and hot test waste liquid;

[0074] To rectify the problems exposed by cold uranium testing;

[0075] After all cold uranium test tasks are completed, and on the premise that all rectifications are ready for partial temporary shutdown, the decision option of not stopping is retained, maintaining the uranium circulation state and directly transitioning to hot testing.

[0076] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0077] (1) The cold uranium debugging method for spent fuel reprocessing process provided by the present invention can be applied in a reprocessing plant to achieve a gradual and smooth transition of the cold uranium test in the reprocessing plant, shorten the debugging cycle, and reduce the debugging cost.

[0078] (2) The cold uranium debugging method for spent fuel reprocessing process provided by the present invention saves 2 months of debugging cycle, verifies the cold uranium operation performance of the production line at the lowest cost, determines the appropriate process operation parameters, and lays a good foundation for the smooth implementation of thermal tests.

[0079] (3) The cold uranium debugging method for spent fuel reprocessing process provided by the present invention optimizes and determines a total of thousands of process operation parameters, and all core indicators are achieved. Its debugging cycle and quality control are at the leading domestic and international advanced level. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0081] Figure 1 A Gantt chart of a method for debugging cold uranium in a spent fuel post-processing process provided by the present invention. DETAILED DESCRIPTION

[0082] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0083] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0084] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0085] like Figure 1 As shown, the present invention provides a method for debugging cold uranium in a spent fuel post-processing process, comprising the following steps:

[0086] S1. Uranium Acid Preparation Sub-stage

[0087] It includes two parts: uranium dissolution and acid transition of chemical separation system, which are carried out independently, to prepare for the introduction of uranium into the raw material 1AF to be extracted in a cycle of uranium-plutonium co-extraction.

[0088] S101, Uranium Dissolution

[0089] The uranium distribution is preset according to 80% loading of system equipment such as the head end, co-decontamination separation, uranium secondary cycle, uranium tertiary cycle, solvent regeneration, and evaporation concentration. An intermediate buffer tank is reserved and the minimum uranium inventory that meets the uranium cycle is calculated as the target value for uranium dissolution.

[0090] Establish a monitoring mechanism to implement monitoring at least twice a day to promptly detect uranium losses and assist in troubleshooting abnormal operating conditions.

[0091] Verify the functionality of the uranium dissolution system, achieve normal dissolution of uranium dioxide and uranium trioxide powders, and prepare uranyl nitrate solution after seasoning as the 1AF cold uranium solution required for the cold uranium test.

[0092] S102, acid transition

[0093] Chemical separation systems such as co-decontamination separation, plutonium purification, and uranium purification use parameters determined by chemical linkage tests, replace each aqueous phase reagent in the chemical separation system with nitric acid of corresponding concentration, start acid transition, and establish a steady state for the extraction system;

[0094] Establish organic phase self-circulation for co-decontamination separation, plutonium purification and solvent regeneration, and uranium purification and solvent regeneration respectively. Considering that the irradiation of the feed liquid of the co-decontamination separation system and the plutonium purification system is much higher than that of the feed liquid of the uranium purification system, in order to maximize the utilization rate of the solvent, determine the principle of sending the regenerated solvent of the uranium purification system to the co-decontamination separation and plutonium purification system for reuse, that is, establish a plant-wide organic phase circulation of "low irradiation system → high irradiation system → solvent distillation → low irradiation system" to verify the plant-wide organic phase circulation operation mode, and conduct organic phase monitoring more than twice a day to promptly detect organic phase losses and assist in the investigation of abnormal operating conditions;

[0095] Verify the flux matching of the solvent regeneration system, and verify the operation mode of the coexistence of kerosene self-circulation and one-time pass - first, operate in a one-time pass mode, store a certain volume of kerosene in the waste kerosene storage tank, and then switch the deoiling tank to the kerosene self-circulation mode. When the TBP content of the aqueous phase after deoiling is close to the limit or reaches the set replacement cycle, the waste kerosene is transported to the organic phase mixing tank to participate in the extractant seasoning, or returned to the front-end extraction equipment at a low flow rate to complete the operation, and then replaced with fresh kerosene, and repeated the operation; secondly, appropriately increase the overall system extractant TBP concentration to offset the dilution effect of kerosene on the organic phase when it passes through once, so as to ensure the extraction effect.

[0096] Verify the solvent distillation processing capacity, product quality and residual liquid production;

[0097] Based on the principle of waste minimization, a special feed tank for chemical test waste liquid and a special receiving tank for cold uranium test waste liquid are set up to isolate chemical test waste liquid from cold uranium test waste liquid. The waste liquid treatment evaporator first continues to treat the chemical test waste liquid, and neutralizes and discharges it in time according to the situation. After the treatment is completed, the cold uranium waste liquid is treated.

[0098] Temporary manholes or cover plate bayonet holes are set for the mixing and clarifying tank, the raffinate and product liquid storage tank, and the emptying tank. They are not welded and sealed for the time being, so as to directly observe the inter-stage operation of the mixing and clarifying tank, the emulsion generation, the phase entrainment, etc., and retain the manual processing capacity;

[0099] For the head-end hot chamber, plutonium tail-end hot chamber, sampling cabinet, glove box and other chambers, the penetration parts and holes will not be sealed for the time being, and the ability to add and adjust electrical / instrumentation and control functions will be retained.

[0100] S2: Uranium cycle establishment sub-stage

[0101] S201, Chemical Separation System Uranium Cycle

[0102] Introduce 1AF cold uranium liquid, gradually open up the main path, reuse path, and waste liquid path, and establish a uranium cycle:

[0103] Main route: The introduced 1AF cold uranium liquid is subjected to the "enrichment process" of co-decontamination separation, uranium secondary circulation, and uranium tertiary circulation to obtain 3EU;

[0104] Multiplexing path: 3EU is evaporated and concentrated and returned to the head end to prepare 1AF;

[0105] Waste liquid route: 1AW+1AXXW, 2AW, and 2DW are used for evaporation and concentration of "high-level" waste liquid, and 3DW, waste acid and alkali, leaching acid, etc. are used for evaporation and concentration of medium- and low-level waste liquid. The resulting residual liquid is all treated with cement solidification and is prohibited from being transported to high-level amplification tanks;

[0106] At this time, the system does not introduce reducing agents (quaternary uranium / hydrazine / hydroxylamine) and oxidizing agents (nitrogen oxides / sodium nitrite), specifically 1B unit stripping agent, 2B unit stripping agent, 2DF seasoning unit reducing agent, 2D unit detergent, 2AF / OF / 2DW seasoning unit nitrogen oxides, 1AF seasoning unit oxidizing agent, 3D unit oxidizing agent, etc.;

[0107] On the basis of maintaining the stability of the uranium cycle, the continuous and stable operation capabilities of the chemical separation system and the waste liquid treatment system are tested, the uranium yield of each unit is verified, the matching, continuity and stability between the systems are verified, and the optimal operating range of the parameters is further verified.

[0108] S202, plutonium purification and plutonium tail end internal circulation (uranium)

[0109] The plutonium purification system uses the 1BP uranium-containing liquid normally produced by the co-decontamination separation system as 2AF for cold uranium experiments on extraction, washing, stripping and supplementary extraction;

[0110] The plutonium tail system receives the 2BP liquid (trace uranium) from the plutonium purification system to simulate OF conditioning, simulate precipitation filtration, and mother liquor destruction, thus establishing a plutonium line cycle of "2BP→OF→OW→2AF";

[0111] During the cold uranium test phase, no uranium will be introduced into the hot cell line at the tail end of the plutonium. Only no-load linkage tests of the hot cell line will be carried out to avoid the problem of uranium residue in the hot cell line affecting the plutonium products of subsequent hot tests.

[0112] S203, common system matching test

[0113] Verify the analytical testing methods for cold uranium test samples;

[0114] Verify the compatibility of the automatic sampling and delivery system;

[0115] Conduct plant-wide filter DOP tests;

[0116] Verify the overall performance of the ventilation and exhaust system of the entire plant to ensure that the negative pressure in each area meets the requirements;

[0117] Initial testing of radiation monitoring equipment such as regional gamma monitors, criticality alarms, neutron counting rate meters, plutonium inventory monitors, and offline low-level liquid activity monitors;

[0118] After uranium is introduced into each system, the monitoring data such as liquid level, density, interface, etc. will change significantly, and the parameters of the DCS control system of the entire plant should be adjusted for matching.

[0119] S3, inlet and outlet balance sub-stage

[0120] S301, first end cold uranium test

[0121] After the shearing machine has completed the no-load and disassembly tests, the shearing system load linkage test is independently carried out using carbon steel simulation components to confirm that the functions of each mechanical and exhaust system are normal (without installing the iodine filter);

[0122] On the basis of stable uranium circulation, cold uranium components are used to conduct full-process tests such as component transfer, lifting, shearing, waste transfer, dissolution, clarification, conditioning, and metering. 1AF cold uranium liquid is prepared and introduced into the uranium circulation. The corresponding batch of 3EU at the tail end of uranium is used as fluidized bed preparation.

[0123] Verify the shear dissolution performance and processing throughput, carry out variable tests with different shear lengths, confirm relevant parameters such as negative pressure, dissolved gas peak, acid recovery, and verify the switching function of the north-south line shearing machine;

[0124] Confirm that the mechanical processes such as basket rotation, cladding dumping, end receiving, and waste transfer are normal;

[0125] Establish temporary reception measures for spent cladding and terminals and transfer them to the low- and medium-level solid waste treatment system;

[0126] Verify the solid-liquid separation effect of sedimentation centrifugation, carry out variable tests on parameters such as feed flow rate and amplitude, and obtain the best operating conditions;

[0127] Establish temporary slag water filtration measures to transfer cold uranium waste slag to the low- and medium-level solid waste treatment system;

[0128] Use cold uranium clear liquid to conduct a seasoning test and prepare qualified 1AF cold uranium liquid;

[0129] Use 1AF cold uranium liquid to verify the reliability of the hardware and software for precise measurement and calculate the uncertainty.

[0130] S302, uranium tail cold uranium test

[0131] The head end and the uranium tail end match to execute feeding and discharging: when the shearing machine starts to shear the cold uranium components, the fluidized bed at the uranium tail end enters fluidization; when the 1AF cold uranium liquid produced by shearing and dissolving starts to feed the 1AX column, the fluidized bed starts to discharge continuously; after the shearing and dissolving test of the last group of cold uranium components is completed, the fluidized bed stops discharging according to the total uranium amount of the system;

[0132] Conduct fluidized bed denitrification discharge test to verify various parameters such as feed flow rate, three-stream gas flow rate, temperature at each point, bed pressure difference, negative pressure, backwashing, elution, etc., and determine the best operating conditions;

[0133] Confirm that the screw conveyor, uranium product packaging box, uranium product transfer, electric rail trolley, gripper, storage well, etc. function normally;

[0134] Before the end of the cold uranium test, the 3EU concentrate that can meet the minimum inventory of uranium circulation will be temporarily stored in the start-up and shutdown liquid storage system for the cold uranium transition during the hot test.

[0135] S4, Redox sub-stage

[0136] S401, introduction of redox agent

[0137] After the extraction system has established a steady state of uranium, the redox agent can be introduced to carry out the test;

[0138] Before introducing the reducing agent, fully test the oxidant output efficiency and introduce the oxidant in advance to avoid the problem of the reducing agent entering the evaporator due to incomplete oxidation of the liquid;

[0139] The amount of reducing agent introduced is reduced to 30% of normal operation, and the oxidizing agent is introduced in a matching amount;

[0140] Verify the performance of tetravalent uranium preparation, obtain parameters such as electrolysis efficiency, order, hydrazine concentration, temperature, etc., and determine the optimal operating conditions;

[0141] Verify the NOx preparation performance, obtain NOx output efficiency, and verify the reliability of 2AF, OF, and 2DW oxidation seasoning processes.

[0142] S402, three wastes full process matching operation

[0143] The systems for high-level radioactive waste treatment, deep purification, discharge of tritium-containing wastewater, treatment of medium- and low-level radioactive wastewater, cement solidification, discharge of purified wastewater, solvent distillation, incineration of distillation residues and light kerosene are matched and operated to receive and treat cold uranium wastewater, further confirm the treatment capacity, and uniformly treat uranium-containing wastewater with cement solidification. High-level amplification tanks and slag water tanks are not used;

[0144] The low- and medium-level radioactive solid waste treatment and temporary storage, combustible waste treatment and other systems are operated in a coordinated manner, cold uranium solid waste is received and processed, and the processing capacity is further confirmed. Uranium-containing solid waste is uniformly treated as low- and medium-level radioactive waste, and the high-level / alpha waste treatment system is not activated;

[0145] The process tail gas treatment, nitrogen oxide absorption, plant exhaust, exhaust tower and other systems are matched and operated (without installing iodine filter), receiving and treating cold uranium waste gas to further confirm the treatment capacity.

[0146] S403, Parking rectification

[0147] Complete the welding and sealing of covers / manholes of all storage tanks and mixing and clarifying tanks;

[0148] Complete the sealing and testing of large hot chambers and box chambers;

[0149] Set up a special feed tank for cold uranium test waste liquid and a special receiving tank for hot test waste liquid, and establish isolation between cold uranium test waste liquid and hot test waste liquid;

[0150] To rectify the problems exposed by cold uranium testing;

[0151] After all cold uranium test tasks are completed, and on the premise that all rectifications are ready for partial temporary shutdown, the decision option of not stopping is retained, maintaining the uranium circulation state and directly transitioning to hot testing.

[0152] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0153] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for debugging cold uranium in a spent fuel reprocessing process, characterized in that: The steps include: S1. Uranium Acid Preparation Sub-stage It includes two parts of independent uranium dissolution and acid transition of chemical separation system, which prepares for the introduction of uranium into the raw material 1AF to be extracted in one cycle of uranium-plutonium co-extraction; S2, uranium cycle establishment sub-stage; S3, inlet and outlet balance sub-stage; S4, redox substage.

2. The method for cold uranium debugging of spent fuel reprocessing process according to claim 1, characterized in that: The uranium dissolution specifically comprises the following steps: Preset uranium distribution according to the head end, co-decontamination separation, uranium second cycle, uranium third cycle, solvent regeneration, and 80% loading of evaporation and concentration equipment, reserve intermediate buffer tanks, and calculate the minimum uranium inventory that meets the uranium cycle as the target value for uranium dissolution; Establish a monitoring mechanism to implement monitoring at least twice a day to promptly detect uranium losses and assist in troubleshooting abnormal operating conditions; Verify the functionality of the uranium dissolution system, achieve normal dissolution of uranium dioxide and uranium trioxide powders, and prepare uranyl nitrate solution after seasoning as the 1AF cold uranium solution required for the cold uranium test.

3. The method for cold uranium debugging of spent fuel reprocessing process according to claim 2, characterized in that: The acid transition specifically comprises the following steps: The parameters determined by chemical linkage tests were used for co-decontamination separation, plutonium purification, and uranium purification. The corresponding concentrations of nitric acid were used to replace the various aqueous phase reagents in the chemical separation system, start the acid transition, and establish the steady state of the extraction system; Establish organic phase self-circulation for co-decontamination separation, plutonium purification and solvent regeneration, and uranium purification and solvent regeneration respectively; monitor the organic phase more than twice a day to promptly detect organic phase losses and assist in troubleshooting abnormal operating conditions; Verify the flux matching of the solvent regeneration system and the coexistence of kerosene self-circulation and one-time pass operation modes; Verify the solvent distillation processing capacity, product quality and residual liquid production; Based on the principle of waste minimization, a special feed tank for chemical test waste liquid and a special receiving tank for cold uranium test waste liquid are set up to isolate chemical test waste liquid from cold uranium test waste liquid. The waste liquid treatment evaporator first continues to treat the chemical test waste liquid, and neutralizes and discharges it in time according to the situation. After the treatment is completed, the cold uranium waste liquid is treated. Temporary manholes or cover plate bayonet holes are set for the mixing and clarifying tank, the raffinate and product liquid storage tank, and the emptying tank. They are not welded and sealed for the time being, so as to directly observe the inter-stage operation of the mixing and clarifying tank, the emulsion generation, the phase entrainment, etc., and retain the manual processing capacity; For the head-end hot chamber, plutonium tail-end hot chamber, sampling cabinet, glove box and other chambers, the penetration parts and holes will not be sealed for the time being, and the ability to add and adjust electrical / instrumentation and control functions will be retained.

4. The method for debugging cold uranium in spent fuel reprocessing process according to claim 3, characterized in that: The verification of the flux matching of the solvent regeneration system and the coexistence of the kerosene self-circulation and one-time passing operation modes are specifically as follows: First, operate in a one-time pass mode, store a certain volume of kerosene in the waste kerosene storage tank, then switch the deoiling tank to the kerosene self-circulation mode, when the TBP content of the aqueous phase after deoiling is close to the limit or reaches the set replacement cycle, the waste kerosene is transported to the organic phase mixing tank to participate in the extractant seasoning, or returned to the front-end extraction equipment at a low flow rate to run completely, and then replaced with fresh kerosene, and the operation is repeated; secondly, appropriately increase the overall TBP concentration of the system's extractant to offset the dilution effect of kerosene on the organic phase when it passes through once, thereby ensuring the extraction effect.

5. The method for cold uranium debugging of spent fuel reprocessing process according to claim 3, characterized in that: The S2 specifically includes the following steps: S201, Chemical Separation System Uranium Cycle Introduce 1AF cold uranium liquid, gradually open up the main path, reuse path, and waste liquid path, and establish a uranium cycle. At this time, the system does not introduce reducing agents and oxidizing agents; on the basis of maintaining the stability of the uranium cycle, verify the uranium yield of each unit, verify the matching, continuity, and stability between the systems, and further verify the optimal operating range of the parameters; S202, plutonium purification and internal circulation of plutonium tail The plutonium purification system uses the 1BP uranium-containing liquid normally produced by the co-decontamination separation system as 2AF for cold uranium experiments on extraction, washing, stripping and supplementary extraction; The plutonium tail system receives the 2BP liquid from the plutonium purification system to simulate OF conditioning, simulate precipitation filtration, and mother liquor destruction, and establishes a plutonium line cycle of "2BP→OF→OW→2AF"; During the cold uranium test phase, uranium is not introduced into the hot cell line at the tail end of the plutonium. Only no-load linkage tests of the hot cell line are carried out to avoid the problem of uranium residue in the hot cell line affecting the plutonium products of subsequent hot tests. S203, common system matching test Verify the analytical testing methods for cold uranium test samples; Verify the compatibility of the automatic sampling and delivery system; Conduct plant-wide filter DOP tests; Verify the overall performance of the ventilation and exhaust system of the entire plant to ensure that the negative pressure in each area meets the requirements; Initial testing of regional gamma monitors, criticality alarms, neutron count rate meters, plutonium inventory monitors, and offline low-level liquid activity monitors; After uranium is introduced into each system, the liquid level, density and interface monitoring data will change significantly, and the DCS control system parameters will be adjusted for matching.

6. The method for cold uranium commissioning of spent fuel reprocessing process according to claim 5, characterized in that: The uranium cycle includes: Main route: The introduced 1AF cold uranium liquid is subjected to co-decontamination separation, uranium secondary circulation, and uranium tertiary circulation "enrichment process" to obtain 3EU; Multiplexing path: 3EU is evaporated and concentrated and returned to the head end to prepare 1AF; Waste liquid route: 1AW+1AXXW, 2AW, and 2DW are used for evaporation and concentration of "high-level" waste liquid; 3DW, waste acid and alkali, and elution acid are used for evaporation and concentration of medium- and low-level waste liquid. The resulting residual liquid is all solidified with cement and is prohibited from being transported to high-level amplification tanks.

7. The method for cold uranium commissioning of spent fuel reprocessing process according to claim 5, characterized in that: The S3 specifically includes the following steps: S301, head end cold uranium test; S302, uranium tail end cold uranium test.

8. The method for cold uranium commissioning of spent fuel reprocessing process according to claim 7, characterized in that: The S301 specifically includes the following steps: After the shearing machine has completed the no-load and disassembly tests, the shearing system load linkage test is independently carried out using carbon steel simulation components to confirm that the functions of each mechanical and exhaust system are normal; On the basis of stable uranium circulation, cold uranium components are used to carry out full-process tests of component transfer, lifting, shearing, waste transfer, dissolution, clarification, conditioning, and metering, prepare 1AF cold uranium liquid, and introduce it into uranium circulation, and the corresponding batch of 3EU at the tail end of uranium is used as fluidized bed preparation; Verify the shear dissolution performance and processing throughput, conduct variable tests with different shear lengths, confirm the parameters related to negative pressure, dissolved gas peak, and acid recovery, and verify the switching function of the north-south line shearing machine; Confirm that the mechanical processes of basket rotation, cladding dumping, end receiving, and waste transfer are normal; Establish temporary reception measures for spent cladding and terminals and transfer them to the low- and medium-level solid waste treatment system; Verify the solid-liquid separation effect of sedimentation centrifugation, carry out variable tests on feed flow rate and amplitude parameters, and obtain the best operating conditions; Establish temporary slag water filtration measures to transfer cold uranium waste slag to the low- and medium-level solid waste treatment system; Use cold uranium clear liquid to conduct a seasoning test and prepare qualified 1AF cold uranium liquid; Use 1AF cold uranium liquid to verify the reliability of the hardware and software for precise measurement and calculate the uncertainty.

9. The method for cold uranium commissioning of spent fuel reprocessing process according to claim 8, characterized in that: The S302 specifically includes the following steps: The head end and the uranium tail end match to execute feeding and discharging: when the shearing machine starts to shear the cold uranium components, the fluidized bed at the uranium tail end enters fluidization; when the 1AF cold uranium liquid produced by shearing and dissolving starts to feed the 1AX column, the fluidized bed starts to discharge continuously; after the shearing and dissolving test of the last group of cold uranium components is completed, the fluidized bed stops discharging according to the total uranium amount of the system; Conduct fluidized bed denitrification discharge test to verify the feed flow rate, three-stream gas flow rate, temperature at each point, bed pressure difference, negative pressure, backwashing, and elution parameters to determine the best operating conditions; Confirm that the screw conveyor, uranium product packaging box, uranium product transfer, electric rail trolley, gripper, and storage well are functioning properly; Before the end of the cold uranium test, the 3EU concentrate that can meet the minimum inventory of uranium circulation will be temporarily stored in the start-up and shutdown liquid storage system for the cold uranium transition during the hot test.

10. The method for cold uranium commissioning of spent fuel reprocessing process according to claim 9, characterized in that: The S4 specifically includes the following steps: S401, introduction of redox agent After the extraction system has established a steady state of uranium, the redox agent can be introduced to carry out the test; Before introducing the reducing agent, fully test the oxidant output efficiency and introduce the oxidant in advance to avoid the problem of the reducing agent entering the evaporator due to incomplete oxidation of the liquid; The amount of reducing agent introduced is reduced to 30% of normal operation, and the oxidizing agent is introduced in a matching amount; Verify the performance of tetravalent uranium preparation, obtain electrolysis efficiency, order, hydrazine concentration, temperature parameters, and determine the best operating conditions; Verify the performance of NOx preparation, obtain NOx output efficiency, and verify the reliability of 2AF, OF, and 2DW oxidation seasoning processes; S402, three wastes full process matching operation The systems for high-level radioactive waste treatment, deep purification, discharge of tritium-containing wastewater, treatment of medium- and low-level radioactive wastewater, cement solidification, discharge of purified wastewater, solvent distillation, incineration of distillation residue and light kerosene are matched and operated, receiving and treating cold uranium wastewater, further confirming the treatment capacity, and uniformly treating uranium-containing wastewater with cement solidification, without using high-level amplification tanks and slag water tanks; The low- and medium-level radioactive solid waste treatment and temporary storage and combustible waste treatment systems are operated in coordination, cold uranium solid waste is received and processed, and the processing capacity is further confirmed. Uranium-containing solid waste is uniformly treated as low- and medium-level radioactive waste, and the high-level / alpha waste treatment system is not activated; The process tail gas treatment, nitrogen oxide absorption, plant exhaust, exhaust tower and other systems are matched and operated to receive and treat the cold uranium waste gas and further confirm the treatment capacity; S403, Parking rectification Complete the welding and sealing of covers / manholes of all storage tanks and mixing and clarifying tanks; Complete the sealing and testing of large hot chambers and box chambers; Set up a special feed tank for cold uranium test waste liquid and a special receiving tank for hot test waste liquid, and establish isolation between cold uranium test waste liquid and hot test waste liquid; To rectify the problems exposed by cold uranium testing; After all cold uranium test tasks are completed, and on the premise that all rectifications are ready for partial temporary shutdown, the decision option of not stopping is retained, maintaining the uranium circulation state and directly transitioning to hot testing.

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