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Hydrogen Assessment Tool for the Emergency Operating Centre

Abstract of the technical presentation presented at:
2nd International CNS Conference on Fire Safety and Emergency Preparedness for the Nuclear Industry
September 17–20, 2017

Prepared by:
Samuel Gyepi-Garbrah
Canadian Nuclear Safety Commission


During a nuclear emergency, the Technical Assessment Group (TAG) of the Canadian Nuclear Safety Commission’s (CNSC) Emergency Operations Centre (EOC) performs an independent assessment of the onsite conditions and potential offsite consequences. This CNSC assessment is a critical input for the federal government’s response.

Lessons learned from the Fukushima Daiichi accident highlighted the importance of an understanding of hydrogen (H2) sources and concentration in containment under accident conditions. Presently, computational tools and aids are relied upon to calculate the hydrogen source term, its concentration and its potential for burns in containment. Such tools, while providing a simple assessment method, need improvements to reduce uncertainty and increase accuracy. To improve the predictive capability for assessing the hydrogen burn challenges, the CNSC has developed the Containment Hydrogen Assessment Tool (CHAT). CHAT forms part of the CNSC tool set in support of its EOC capabilities for the TAG.

In this presentation, the improved CHAT code methodology, illustrative results and CHAT’s place in the overall CNSC EOC toolset for H2 risk management during an accident will be discussed.

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