ML16328A116

ACRS Views on Fire Protection Research and Fire-Related Systems Interactions

ML16328A116
Person / Time
Issue date:	07/16/1986
From:	Ward D Advisory Committee on Reactor Safeguards
To:	Zech L NRC/Chairman
References
D860716
Download: ML16328A116 (2)

Text

D860716 Honorable Lando W. Zech, Jr.

Chairman U.S. Nuclear Regulatory Commission Washington, D.C. 20555

SUBJECT:

ACRS VIEWS ON FIRE PROTECTION RESEARCH AND FIRE-RELATED SYSTEMS INTERACTIONS During its 315th meeting, July 10-12, 1986, the Advisory Committee on Reactor Safeguards considered various activities associated with nuclear power plant fire protection provisions, including the Appendix R modi-fication process and fire-related portions of the safety research program. These matters were also discussed by the ACRS Subcommittee on Auxiliary Systems at a meeting held on June 26, 1986. We identified specific items of concern in the safety research area. We would like to share these since they may be of interest to you, and as a basis for reconsideration of resource allocation for fire-related research.

It is our understanding that all fire-related safety research programs will be terminated at various stages of completion by the end of FY 1986. In FY 1987, the Office of Nuclear Regulatory Research intends to perform a scoping study to reexamine the program needs, to determine the likely level of fire risk, and to establish future priorities. Our first concern is the loss of program momentum and information that will result from premature termination of ongoing activities while awaiting results of the proposed scoping study. Any termination of needed research is a loss, and will be costly to reconstitute later.

The NRC Staff indicates that, based on Probabilistic Risk Analyses (PRAs) that have been performed, there is a significant contribution to core-melt frequency from fire in a number of plants. Although the risk associated with fire is subject to large uncertainties, it is clearly nontrivial and the ability of fire to exacerbate severe accident situa-tions has already been demonstrated. Therefore, one needs to understand better how fires can start and propagate, and the consequential effects of fire and fire-fighting measures (or their inadvertent actuation) on safety-related equipment throughout the plant. Such information needs to be developed if the risk is to be properly analyzed and minimized, and the value-impact of potential backfits appropriately calculated.

The uncertainty must be narrowed if the results are to be useful for decision making.

In this regard, fires in the control room area are of special concern because of the confluence of essential plant control systems and the likely sensitivity of control room components to the adverse environment resulting from fire and fire suppression. Although considerable re-search has been done in this area, important work remains to be complet-ed and documented concerning fire source characterization, full-scale room environment tests, component failure threshold tests, and valida-tion of fire environment computer codes against full-scale room tests.

A majority of this work for FY 1986-1987 will remain unfinished or undone. The fire PRAs performed to date have not had the benefit of sufficient test data and information such as would be developed by this work. This significantly increases the uncertainty in the risk esti-mates. In addition, much of this work would add to a technical base that would be applicable to the analysis of fire situations, risk aversion, and value-impact considerations throughout the plant.

Our second concern relates to the fire-induced control system inter-actions issue which we thought was going to be within the scope of the resolution of USI A-17, "Systems Interactions in Nuclear Power Plants."

We are now aware that the proposed resolution of USI A-17 does not include fire-induced interactions or those created by fire mitigation efforts or the effects of a seismic event on fire mitigation features.

We are concerned that this aspect of the issue has been overlooked. A research effort may be required to explore adequately the issue and its ramifications, including its potential contribution to common cause and severe accidents. The results of some of the previous and proposed (but, now terminated) fire-related research may be needed in support of this effort.

We urge reconsideration of the budget and manpower allocations that have led to the termination of the fire-related portions of the safety research program, and would like to be kept informed of how the fire-induced system interaction issue will be handled. We are anxious to see a continuity of effort on fire-related research while the Staff deter-mines its future priorities.

Finally, we believe that if the NRC does not perform this research there may be a need for a set of regulations requiring industry to deal with the uncertain aspects of component behavior under various fire con-ditions.

Sincerely, David A. Ward Chairman