Decision Evaluation Method for Active Emissions from Nuclear Power Plant Containment

Abstract

The decision-making evaluation method for the active discharge of nuclear power plant containment, including overpressure threat mitigation decision-making evaluation steps, further includes hydrogen threat mitigation decision-making evaluation steps, discharge termination decision-making evaluation steps, radioactive fission product release mitigation evaluation steps, overpressure threat mitigation decision-making evaluation steps The steps include: calculating the expected value M1 of radioactive dose consequences of active discharge; first calculating the critical failure probability of containment overpressure when M1 is equal to the expected value N1 of non-discharged radioactive dose consequences; then determining the critical failure pressure F1 of containment overpressure; considering a certain margin Calculate the recommended setting value F0 of the containment pressure after the measurement; when the pressure of the containment reaches F0, active discharge is requested. The invention provides an evaluation method for the decision-making of containment active discharge under severe accidents, provides decision-making basis for emergency command, actively implements containment discharge, alleviates containment overpressure or hydrogen threat, relieves release of fission products, and reduces radioactivity after serious accidents Pollution.

Description

technical field [0001] The invention relates to the technical field of nuclear power plant accident handling, in particular to a decision-making evaluation method for active discharge of containment shells in nuclear power plants. Background technique [0002] According to the nuclear power safety concept of defense in depth and multiple barriers, the containment is the last barrier to prevent the release of radioactive fission products. Many domestic pressurized water reactor nuclear power plants have set up containment filtration and exhaust system (Containment Filtration and Exhaust System, English abbreviation CFES) in order to alleviate the fission product release of large dry containment. CFES can effectively filter volatile fission products and aerosols, usually filter The efficiency reaches more than 99%. In order to alleviate the release of fission products caused by containment leakage, active filtering and emission can be considered. [0003] A serious accident o...

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Problems solved by technology

[0006] Problem 1. In the management of severe accidents in nuclear power plants, active containment venting is required to mitigate the threat of containment overpressure

Moreover, some power plants only give the opening pressure of the discharge in the severe accident management guidelines, without clearly specifying the conditions for terminating the discharge. Some power plants simply set the value of the containment pressure, such as half or 40% of the opening pressure as the closing setting value , the lack of rigorous evaluation methods

[0007] Question 2. Currently, in the management of severe accidents in power plants, the purpose of applying filter discharge system for active containment discharge is limited to alleviating the threat of overpressure and hydrogen to the integrity of containment

[0008] Question 3, the release of fission products caused by the "normal" leakage of the containment under severe accidents is attracting attention in the field of nuclear power safety. The allowable leakage rate under the design pressure is 0.1-0.3% / day, and it is assumed that ten times the normal leakage rate exceeds the design pressure. Leakage, high level of radioactivity in the leaking gas

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