A Short History of Fire Safety Research Sponsored by the U.S. Nuclear Regulatory Commission, 1975-2008 (NUREG/BR-0364)
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Date Published: June 2009
Hugh W. Woods and Mark Henry Salley
Fire Research Branch
Office of Nuclear Regulatory Research
U. S. Nuclear Regulatory Commission
Washington, DC 20555-0001
Steven P. Nowlen
Sandia National Laboratories
Risk and Reliability Analysis Department 6761
PO Box 5800
Albuquerque, NM 87185
This report summarizes research conducted by the U.S. Nuclear Regulatory Commission (NRC) from its inception through 2008, to identify and reduce challenges to the ability of a nuclear power plant (NPP) to safely shut down when necessary to prevent damage to its nuclear core due to indirect effects of the fire, such as fire-damage to its emergency core cooling systems.
The NRC was created on January 19, 1975, by the Energy Reorganization Act, which abolished the Atomic Energy Commission (AEC) and replaced it with the NRC, the Energy Research and Development Administration, and the Energy Resources Council. The latter two agencies later became part of the U.S. Department of Energy (DOE), which was created on October 1, 1977.
Thus the AEC, which had been charged with regulation and promotion of the nuclear power industry, was replaced by the NRC (which inherited only the regulatory function) and DOE (which inherited the promotional function).
When the NRC was created, regulation of the nuclear power industry was based primarily on a set of deterministic rules. Those rules, including the ones related to fire safety, relied heavily on the design requirements for large, nonnuclear industrial facilities. They did not rely on quantitative safety evaluations, such as probabilistic risk assessments (PRAs). The NRC did not publish the first PRA, WASH-1400, “Reactor Safety Study—An Assessment of Accident Risks in U.S. Commercial Nuclear Power Plants,” (NUREG-75/014) until October 1975.
However, three events happened early in the NRC’s existence that accelerated a trend toward the increased use of quantitative methods in NPP regulation. The first was a major fire at the Browns Ferry Nuclear Power Plant (Figure 1, inside front cover) on March 22, 1975. This accident focused attention on fire as a “common mode” cause of multiple safety system failures, a factor that had not been adequately considered by the deterministic criteria used in the plant’s design. The second event was the October 1975 publication of WASH-1400, which showed that quantitative safety evaluations were feasible and could be used to improve NPP safety. The third event was a severe accident at the Three Mile Island Unit 2 NPP on March 28, 1979.
In 1995, the NRC formalized this trend toward the increased use of quantitative methods in NPP regulation in the following Commissioners’ policy statement:
The use of PRA technology should be increased in all regulatory matters to the extent supported by the state-of-the-art in PRA methods and data and in a manner that complements the NRC’s deterministic approach and supports the NRC’s traditional defense-in-depth philosophy.
This report covers the most significant NRC-sponsored fire-safety research programs over a time period from the agency’s creation, when regulation was based primarily on deterministic (nonquantitative) rules, to the present time, when regulation is rapidly becoming “risk-informed,” using a combination of quantitative and deterministic considerations.
This report is part of the Knowledge Management Program being conducted by the NRC’s Office of Nuclear Regulatory Research, Division of Risk Analysis, Fire Research Branch.