A method for assessing chemical effects after an accident in a pressurized water reactor nuclear power plant

Abstract

The invention provides a method for evaluating the post-accident chemical effect of a pressurized water reactor nuclear power plant. The method comprises the following steps: collecting relevant environmental parameters in a post-accident containment of the nuclear power plant; determining the chemical compositions of a chemical precipitate inside the containment, and introducing the environmental parameters into a plurality of preset analytical models to obtain the corresponding yield of each chemical composition respectively in the chemical precipitate; obtaining maximum value of the yield obtained by the same type of chemical compositions in each analytical model respectively according to the types of the chemical compositions, and taking the maximum value of the corresponding yield of each chemical composition as a final result. Through the implementation of the method, the type and yield of the post-accident chemical precipitate of the pressurized water reactor nuclear power plant can be evaluated, so that an accurate basis is provided for evaluating the influence of the chemical product on the performance of a pit filter and the functional reliability of ECCS and CSS recycling, improvement measures are further established, and the purpose of improving the safety of a pressurized water reactor unit is reached.

Description

technical field [0001] The invention relates to the technical field of nuclear power plant accident treatment, in particular to a method for evaluating chemical effects after an accident in a pressurized water reactor nuclear power plant. Background technique [0002] After a LOCA (Loss of Coolant Accident) occurs in a pressurized water reactor nuclear power plant, the high-temperature and high-pressure reactor coolant will be released into the containment of the pressurized water reactor unit, and the CSS (Containment The Spray System (Containment Spray System) also releases water containing pH buffers, so that after the LOCA accident the containment is filled with water, reactor coolant compounds, pH formed from sodium hydroxide, sodium tetraborate, and trisodium phosphate. The chemical solution composed of buffer and other chemical substances makes the chemical environment in the containment very complex and harsh. [0003] Under the above-mentioned complex and harsh che...

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Problems solved by technology

[0002] After a LOCA (Loss of Coolant Accident) occurs in a pressurized water reactor nuclear power plant, the high-temperature and high-pressure reactor coolant will be released into the containment of the pressurized water reactor unit, and the CSS (Containment The Spray System (Containment Spray System) also releases water containing pH buffers, so that after the LOCA accident, the containment is filled with water, reactor coolant compounds, and pH formed by sodium hydroxide, sodium tetraborate, and trisodium phosphate. Chemical solutions composed of buffers and other chemical substances, resulting in a very complex and harsh chemical environment in the containment

[0003] Under the above-mentioned complex and harsh chemical environment, some materials in the containment will be corroded and decomposed, and then react with certain chemical elements in the above-mentioned chemical solution to form new chemical deposits. Entrained into the pit, and get rid of the interception of the pit filter to reach the downstream pipeline, together with fiber and particle debris, it poses a challenge to the reliability of the recirculation function of ECCS (Emergency Core Cooling System, Emergency Core Cooling System) and CSS

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