Unaddressed issues in fire modelling and risk assessments

The Fire Risk Scoping Study was sponsored by the United States Nuclear Regulatory Commission (NRC) and performed at the Sandia National Laboratories. The study was initiated as a result of previous NRC sponsored fire research efforts which had identified certain fire risk issues that had not been addressed in previously completed commercial nuclear power plant fire risk analyses. The specific objectives of this study were: (1) to review and requantify fire risk scenarios from four fire probabilistic risk assessments in the light of updated databases made available as a result of the NRC sponsored Fire Protection Research Program and updated computer fire modelling capabilities; (2) to identify potentially significant fire risk issues that have not been previously addressed in a fire risk context and to quantify the potential impact of these identified fire risk issues, where possible; and (3) to review current fire regulations and plant implementation practices for relevance to the identified unaddressed fire risk issues. Six new fire risk issues were identified which had not previously been addressed in a fire risk context. These six issues are: (a) control systems interaction; (b) seismic fire interaction; (c) manual fire fighting effectiveness (including smoke control); (d) total environment equipment survival (including the spurious operation of fire suppression systems); (e) the adequacy of fire barrier qualification methods; and (f) the adequacy of analytical tools for fire. Order of magnitude estimates were made to show the relative importance of each of the risk issues. The issues of manual fire fighting effectiveness, control systems interaction and fire code adequacy were identified as those issues with the most significant potential impact. (author). 9 refs, 3 tabs