Design study of hydrogen monitoring equipment for severe accident in containment of nuclear power plant

Abstract

After the Fukushima accident, the risk of hydrogen shall be considered by most countries in nuclear power plants. China national nuclear safety Administration has required that nuclear power plants shall install the hydrogen monitoring measurement equipment for severe accident in containment. There were some equipment used for hydrogen monitoring at severe accident, but some equipment cannot solve the leakage problem, some equipment cannot measure the hypoxic environment, and some have slower response time or long startup time. In this study, we developed a based on Pd–Ag​ alloy hydrogen monitoring equipment, Pd–Ag alloy is selected as hydrogen sensitive material, alumina ceramic is used as substrate, and Pd–Ag alloy film hydrogen core measurement component is prepared by magnetron sputtering technology. Heating​ treatment in sensor is adopted to maintain the environment in which the sensor is located at a constant 198°C environment, and protective and filtering measures are taken to ensure that hydrogen detection is not affected by aerosol and water vapor. Then, study the characterization of hydrogen monitoring equipment. Testing results indicated that the hydrogen measuring component (Pd–Ag) working at a constant temperature does not affect the measurement results and this equipment has the constant line relationship between hydrogen concentration and resistant. The response time of hydrogen decrease is longer than that of hydrogen increase, but it is within 50 s. It also has the high accuracy keeping within 1 vol% at normal anoxic environment and harsh environment. If it is applied to severe accidents in NPPs, it is necessary to study the performance under irradiation conditions in the future.

Keywords

• Severe accident
• Hydrogen monitoring
• Palladium–silver alloy