Nuclear Techniques ›› 2019, Vol. 42 ›› Issue (5): 50601-050601.doi: 10.11889/j.0253-3219.2019.hjs.42.050601

• NUCLEAR ENERGY SCIENCE AND ENGINEERING • Previous Articles     Next Articles

Sensitivity analysis of the hydrogen mole fraction limit for ignition with MELCOR2.2

Xingwei SHI,Qiang SHI,Guoqiang MA,Wei SONG,Bin JIA(),Jiaxu ZUO,Fudong LIU   

  1. 1. Nuclear and Radiation Safety Center, Ministry of Ecology and Environment, Beijing 100082, China
  • Received:2019-01-15 Revised:2019-03-26 Online:2019-05-10 Published:2019-05-16
  • Contact: Bin JIA E-mail:jiabin@chinansc.cn
  • About author:SHI Xingwei, male, born in 1985, graduated from Harbin Engineering University with a doctoral degree in 2013, focusing on safety analysis of nuclear power|SHI Xingwei, male, born in 1985, graduated from Harbin Engineering University with a doctoral degree in 2013, focusing on safety analysis of nuclear power|JIA Bin, E-mail: jiabin@chinansc.cn
  • Supported by:
    Supported by National Science and Technology Major Project(No.2015ZX06002007)

Abstract: Background

In severe accidents, the oxidation behavior of fuel cladding and other metallic materials in core region with steam, and the molten corium-concrete interaction (MCCI) are important source items for releasing hydrogen.

Purpose

This study aims to investigate the sensitivity of the hydrogen mole fraction limit for ignition in the containment to prevent the hydrogen deflagration and explosion.

Methods

The integrated contamination model has been built systemically in large power passive pressurized-water reactor (PWR) using the latest version of MELCOR2.2 code, and the sensitivity analysis of hydrogen molar fraction limit for ignition has been carried out.

Results

The analysis results show that: 1) the higher hydrogen mole fraction limit setting the more obvious pressure peak generated by a single combustion; it will cause the hydrogen deflagration and detonation if the value exceeds the mole fraction limit; 2) the hydrogen ignition is affected by other noncondensible gases to a certain extent. The increase of carbon monoxide molar fraction escalates the hydrogen ignition and, conversely, the carbon dioxide and steam dilute the flammable gases.

Conclusion

Hydrogen ignition is greatly affected by the ignition limit of hydrogen molar fraction, and as an important factor, the other noncondensible gases components in containment are non-negligible. Therefore, it is crucial to combining and diluting the combustible gases for eliminating the potential risk in containment.

Key words: MELCOR2.2, Hydrogen, Mole fraction limit for ignition, Severe accident, Sensitivity analysis

CLC Number: 

  • TL364.4