Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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Analyses of hydrogen risk in containment filtered venting system using MELCOR

  • Received : 2020.07.30
  • Accepted : 2021.07.30
  • Published : 2022.01.25
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Abstract

Hydrogen risk in the containment filtered venting system (CFVS) vessel was analyzed, considering operation pressure and modes with the effect of PAR and accident scenarios. The CFVS is to depressurize the containment by venting the containment atmosphere through the filtering system. The CFVS could be subject to hydrogen risk due to the change of atmospheric conditions while the containment atmosphere passes through the CFVS. It was found that hydrogen risk increased as the CFVS opening pressure was set higher because more combustible gases generated by Molten Core Concrete Interaction flowed into the CFVS. Hydrogen risk was independent of operation modes and found only at the early phase of venting both for continuous and cyclic operation modes. With PAR, hydrogen risk appeared only at the 0.9 MPa opening pressure for Station Black-Out accidents. Without PAR, however, hydrogen risk appeared even with the CFVS opening set-point of 0.5 MPa. In a slow accident like SBO, hydrogen risk was more threatening than a fast accident like Large Break Loss-of-Coolant Accident. Through this study, it is recommended to set the CFVS opening pressure lower than 0.9 MPa and to operate it in the cyclic mode to keep the CFVS available as long as possible.

Keywords

Acknowledgement

This research was supported by the Chung-Ang University Graduate Research Scholarship in 2020, the Nuclear Safety Research Program of the Korea Foundation of Nuclear Safety (KOFONS), with granted financial resources from the Nuclear Safety and Security Commission (NSSC) (Grant Code 1305008-0113-SB113) and a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP: Ministry of Science, ICT and Future Planning) (No. NRF- 2017M2B2B1072552).

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