Analysis method of pool type lead bismuth reactor Po-210 source item

Abstract

The invention belongs to the technical field of radiation protection, and particularly relates to an analysis method for a Po-210 source item of a pool type lead bismuth reactor. The method comprises the following steps: S1, constructing a reactor Po-210 source item analysis model according to specific design parameters of a pool type lead bismuth reactor; s2, the Po-210 generation rate, the velocity field and the temperature field of the pool type lead bismuth cooling agent and the evaporation rates of Po and PoPb in the cooling agent are combined, and Po-210 source item distribution in the cooling agent and the covering gas is obtained; s3, according to the leakage rate of the coverage gas system, obtaining the rate of the Po-210 source item leaked from the coverage gas to the plant; s4, considering the deposition behavior of the Po-210 source item on the factory side and the equipment surface, and considering the behavior that PbPo is in contact with humid air to generate gaseous H2Po, so as to obtain the activity concentration of the Po-210 source item in the factory; and S5, analyzing a Po-210 source item discharged to the environment. According to the invention, modeling analysis is carried out on various physics such as generation, disappearance, migration, evaporation, deposition and the like of the Po-210 source item of the integrated pool type lead-bismuth reactor, and simulation of the Po-210 source item of the pool type lead-bismuth reactor is realized.

Description

Technical Field

[0001] This invention belongs to the field of radiation protection technology, specifically relating to an analysis method for the source term of a pool-type lead-bismuth pile Po-210. Background Technology

[0002] Lead-bismuth reactors, as one of the important reactor types in fourth-generation nuclear energy systems, possess excellent neutronics characteristics and inherent safety. However, when liquid lead-bismuth eutectic (LBE) is used as a coolant, it produces the radioactive isotope Po-210, which is a unique safety issue for lead-bismuth reactors. Po-210 is an extremely toxic radioactive isotope with a half-life of 138 days and is highly volatile, posing a significant threat to human health. Po-210 in the coolant of a lead-bismuth reactor can volatilize into the cover gas space and leak into the plant and the environment, threatening the radiation safety of workers and the public. Therefore, precise analysis of the Po-210 source term in lead-bismuth reactors is necessary. The migration process of Po-210 is closely related to multiple physical fields, including coolant temperature, coolant flow, Po-210 chemical form, and neutron reactions. Currently, comprehensive analytical methods for the Po-210 source term in pool-type lead-bismuth reactors are not yet perfect, lacking a comprehensive analytical method that considers multiple physical processes such as Po-210 generation, disappearance, migration, evaporation, and deposition. Summary of the Invention

[0003] The technical problem solved by this invention is to provide a method for analyzing the Po-210 source term of an integrated lead-bismuth pile, which models and analyzes various physical processes such as the generation, disappearance, migration, evaporation, and deposition of the Po-210 source term in the integrated lead-bismuth pile, thereby simulating the Po-210 source term of the integrated lead-bismuth pile.

[0004] The technical solution adopted in this invention is as follows:

[0005] An analytical method for the source term Po-210 in a pool-type lead-bismuth stack includes the following steps:

[0006] S1. Based on the specific design parameters of the pool-type lead-bismuth reactor, construct the source term analysis model of reactor Po-210;

[0007] S2, combined with the Po-210 production rate, the velocity and temperature fields of the pooled lead-bismuth coolant, and the evaporation rates of Po and PoPb in the coolant, yielded the Po-210 source term distribution in the coolant and the covering gas.

[0008] S3. Based on the leakage rate of the covering gas system, obtain the rate of Po-210 source term leakage of covering gas into the plant.

[0009] S4. Considering the deposition behavior of Po-210 source terms on the plant and equipment surfaces, the behavior of PbPo reacting with humid air to generate gaseous H2Po, and the purification and removal effect in the plant, the activity concentration of Po-210 source terms in the plant is obtained.

[0010] S5. Analyze the source terms of Po-210 emitted into the environment based on the ventilation or leakage situation of the plant.

[0011] The reactor Po-210 source term analysis model includes a Po-210 generation model, a Po-210 migration model, and a Po-210 evaporation model.

[0012] The generation model of Po-210 describes the process of Bi-210 decaying to generate Po-210.

[0013] The generation model of Po-210 is constructed by using the RMC program to build a Monte Carlo analysis model, calculate the process of neutron activation of lead-bismuth coolant to generate Bi-210, obtain an accurate simulation of the generation process of coolant Po-210, and obtain the generation rate of Po-210 generated by coolant activation and decay in different regions of the pool-type lead-bismuth reactor.

[0014] The migration model of Po-210 describes the convective diffusion process of Po-210 in liquid lead-bismuth coolant.

[0015] The migration model of Po-210 uses the COMSOL program to construct a finite element model for coolant flow and heat transfer calculation, and performs coolant flow and heat transfer calculation to obtain the velocity field and temperature field of the coolant in the pool-type lead-bismuth reactor.

[0016] The evaporation model of Po-210 describes the evaporation behavior of Po-210 at the interface between liquid lead bismuth and the covering gas.

[0017] The evaporation model of Po-210 treats Po and PoPb vapors as ideal gases and uses Raoult's law of partial pressures to establish an analysis model for the evaporation rates of Po and PoPb. Based on the coolant temperature at the free liquid surface and the pressure of the covering gas, the evaporation rates of Po and PoPb are obtained.

[0018] The beneficial effects of this invention are:

[0019] (1) The present invention provides a method for analyzing the source term of Po-210 in a pool-type lead-bismuth pile, which comprehensively considers the complete life cycle of Po-210 in the lead-bismuth pile, including the entire process of generation, decay, migration, evaporation and deposition, and the analysis method is more comprehensive and accurate.

[0020] (2) The present invention provides a method for analyzing the Po-210 source term in a pool-type lead-bismuth reactor. It considers the effects of the neutron field, coolant flow field, and temperature field of the pool-type lead-bismuth reactor on the generation, migration, and evaporation of Po-210. It accurately considers the decay and disappearance of Po-210 during the migration process and obtains the Po-210 concentration distribution of the coolant and cover gas in the pool-type lead-bismuth reactor. It also considers in detail the settling, decay, and leakage process of Po-210 after it is released into the plant, accurately simulates the Po-210 concentration in the plant gas space, and obtains the Po-210 activity emitted into the environment. This method achieves accurate analysis of the Po-210 activity throughout the entire process from the inside of the lead-bismuth reactor to the environment, and has potential engineering and economic value. Attached Figure Description

[0021] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in describing the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments recorded in the present invention. Those skilled in the art can derive other drawings from the following drawings without any creative effort.

[0022] Figure 1 A flowchart of an analysis method for the source term of a pool-type lead-bismuth stack Po-210 provided by the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0024] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., refer to the orientation or positional relationship shown in the accompanying drawings, and are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or a connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] like Figure 1 As shown, the present invention provides an analysis method for the Po-210 source term of a pool-type lead-bismuth stack, comprising the following steps:

[0027] S1. Based on the specific design parameters of the pool-type lead-bismuth reactor, construct the source term analysis model for reactor Po-210.

[0028] The reactor Po-210 source term analysis model includes a Po-210 generation model, a Po-210 migration model, and a Po-210 evaporation model;

[0029] The generation model of Po-210 describes the process of generating Po-210 from the decay of Bi-210; the migration model of Po-210 describes the convective diffusion process of Po-210 in liquid lead-bismuth coolant; and the evaporation model of Po-210 describes the evaporation behavior of Po-210 at the interface between liquid lead-bismuth and the covering gas.

[0030] The generation model of Po-210 is constructed by using the RMC program to build a Monte Carlo analysis model, calculate the process of Bi-210 generation by neutron activation of lead-bismuth coolant, and thus obtain an accurate simulation of the generation process of coolant Po-210, and obtain the generation rate of Po-210 generated by coolant activation and decay in different regions of pool-type lead-bismuth reactor.

[0031] The migration model of Po-210 is constructed using the COMSOL program to build a finite element model for coolant flow and heat transfer calculation, and to carry out coolant flow and heat transfer calculation to obtain the velocity field and temperature field of the coolant in the pool-type lead-bismuth reactor.

[0032] The evaporation model of Po-210 treats Po and PoPb vapors as ideal gases and uses Raoult's law of partial pressures to establish an analysis model for the evaporation rate of Po and PoPb. The evaporation rate of Po and PoPb is obtained based on the coolant temperature at the free liquid surface and the pressure of the covering gas.

[0033] S2, combined with the Po-210 production rate, the velocity and temperature fields of the pooled lead-bismuth coolant, and the evaporation rates of Po and PoPb in the coolant, yielded the Po-210 source term distribution in the coolant and the covering gas.

[0034] S3. Based on the leakage rate of the covering gas system, obtain the rate of Po-210 source term leakage of covering gas into the plant.

[0035] S4. Considering the deposition behavior of Po-210 source terms on the plant and equipment surfaces, the behavior of PbPo reacting with humid air to generate gaseous H2Po, and the purification and removal effect in the plant, the activity concentration of Po-210 source terms in the plant is obtained.

[0036] S5. Analyze the source terms of Po-210 emitted into the environment based on the ventilation or leakage situation of the plant.

[0037] While those skilled in the art will recognize that the present invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention, the embodiments should be considered illustrative and non-limiting in all respects. The scope of the invention is defined by the appended claims rather than the foregoing description, and therefore all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0038] Furthermore, it should be understood that although the present invention is described according to embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for analyzing the source term of a pool-type lead-bismuth stack Po-210, characterized in that, Includes the following steps: S1. Based on the specific design parameters of the pool-type lead-bismuth reactor, construct the source term analysis model of reactor Po-210; S2, combined with the Po-210 production rate, the velocity and temperature fields of the pooled lead-bismuth coolant, and the evaporation rates of Po and PoPb in the coolant, yielded the Po-210 source term distribution in the coolant and the covering gas. S3. Based on the leakage rate of the covering gas system, obtain the rate of Po-210 source term leakage of covering gas into the plant. S4. Considering the deposition behavior of Po-210 source terms on the plant and equipment surfaces, the behavior of PbPo reacting with humid air to generate gaseous H2Po, and the purification and removal effect in the plant, the activity concentration of Po-210 source terms in the plant is obtained. S5. Analyze the source terms of Po-210 emitted into the environment based on the ventilation or leakage situation of the plant.

2. The method for analyzing the source term of a pool-type lead-bismuth pile Po-210 according to claim 1, characterized in that, The reactor Po-210 source term analysis model includes a Po-210 generation model, a Po-210 migration model, and a Po-210 evaporation model.

3. The method for analyzing the source term of a pool-type lead-bismuth pile Po-210 according to claim 2, characterized in that, The generation model of Po-210 describes the process of Bi-210 decaying to generate Po-210.

4. The method for analyzing the source term of a pool-type lead-bismuth pile Po-210 according to claim 3, characterized in that, The generation model of Po-210 is constructed by using the RMC program to build a Monte Carlo analysis model, calculate the process of neutron activation of lead-bismuth coolant to generate Bi-210, obtain an accurate simulation of the generation process of coolant Po-210, and obtain the generation rate of Po-210 generated by coolant activation and decay in different regions of the pool-type lead-bismuth reactor.

5. The method for analyzing the source term of a pool-type lead-bismuth pile Po-210 according to claim 4, characterized in that, The migration model of Po-210 describes the convective diffusion process of Po-210 in liquid lead-bismuth coolant.

6. The method for analyzing the source term of a pool-type lead-bismuth pile Po-210 according to claim 5, characterized in that, The migration model of Po-210 uses the COMSOL program to construct a finite element model for coolant flow and heat transfer calculation, and performs coolant flow and heat transfer calculation to obtain the velocity field and temperature field of the coolant in the pool-type lead-bismuth reactor.

7. The method for analyzing the source term of a pool-type lead-bismuth pile Po-210 according to claim 6, characterized in that, The evaporation model of Po-210 describes the evaporation behavior of Po-210 at the interface between liquid lead bismuth and the covering gas.

8. The method for analyzing the source term of a pool-type lead-bismuth pile Po-210 according to claim 7, characterized in that, The evaporation model of Po-210 treats Po and PoPb vapors as ideal gases and uses Raoult's law of partial pressures to establish an analysis model for the evaporation rates of Po and PoPb. Based on the coolant temperature at the free liquid surface and the pressure of the covering gas, the evaporation rates of Po and PoPb are obtained.

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