Second,  NRC published Appendix R, which requires nuclear units operating prior  to January 1, 1979 (called “pre-1979 units”), to implement design  features—such as fire walls, fire wraps, and automatic fire detection and  suppression systems—to protect a redundant system of electrical cables  and equipment necessary to safely shut down a nuclear unit during a fire. 2. 3. In part to simplify the licensing of nuclear units that have many  exemptions, NRC recently began encouraging units to transition to a more  risk-informed approach to nuclear safety in general. According to NRC, Recent Fires at U.S. Commercial Nuclear Units Have Had Limited Safety Significance

NRC officials told us that none of the 125 fires at 54 sites that nuclear unit  operators reported from January 1995 to December 2007 has posed  significant risk to a commercial unit’s ability to safely shut down. As shown in the table 1, the primary reported causes of these fires were  electrical fires. NRC’s data on the location and circumstances  surrounding fire events was consistent with the statements of unit officials  whom we contacted at selected nuclear units. NRC Has Not Resolved Long- standing Issues Affecting Industry’s Compliance with NRC’s Fire Regulations

NRC has not fully resolved several long-standing issues that affect the  commercial nuclear industry’s compliance with existing NRC fire  regulations. These issues include (1) nuclear units’ use of operator manual  actions; (2) nuclear units’ long-term use of interim compensatory  measures; (3) uncertainties regarding the effectiveness of fire wraps for  protecting electrical cables necessary for the safe shutdown of a nuclear  unit; and (4) the regulatory treatment of fire-induced multiple spurious  actuations of equipment that could prevent the safe shutdown of a nuclear  unit. As of April,  2008, NRC has no firm plans for resolving this problem. NRC Lacks a Comprehensive Database to Track Nuclear Units’ Use of Operator Manual Actions, Interim Compensatory Measures, and Exemptions

NRC has no comprehensive database of the operator manual actions or interim  compensatory measures implemented at nuclear units since its regulations  were first promulgated in 1981, in addition to the hundreds of related licensing  exemptions. Furthermore, the shortage of skilled  personnel and concerns about the potential cost of conducting risk  analyses could slow the transition process and limit the number of units  that ultimately make the transition to the new approach. Industry and Academic Experts Expressed Concern about Probabilistic Risk Assessments That Would Be Used under the Risk- Informed Approach

According to industry officials and academic experts we consulted, the  results of a probabilistic risk assessment used in the risk-informed  approach could help units direct safety resources to areas where risk from  accidents could be minimized or where the risk of damage to the core or a  unit’s safe shutdown capability is highest; however, officials also noted  that the absence of significant fire events since the 1975 Browns Ferry fire  limits the relevant data on fire events at nuclear units. NRC and industry officials  stated that they expected that newer units and units with relatively few  exemptions from existing regulations would be less likely to transition to  the new approach, while those with older licenses and extensive  exemptions would make the transition. Compounding these issues, NRC has no central  database of exemptions, operator manual actions, and extended interim  compensatory measures. According  to NRC, nuclear fire safety can be considered to be degraded when  reliance on passive measures is supplanted by manual actions or  compensatory measures. To examine the status of the nuclear industry’s implementation of the risk- informed approach to fire safety advocated by NRC, we met with and  reviewed documents provided by officials from NRC, industry, and public  interest groups, as well as academic officials with research experience in  fire safety and risk analysis. Major Management Challenges and Performance Risks: Nuclear  Regulatory Commission.
Why GAO Did This Study

After a 1975 fire at the Browns Ferry nuclear plant in Alabama threatened the unit's ability to shut down safely, the Nuclear Regulatory Commission (NRC) issued prescriptive fire safety rules for commercial nuclear units. However, nuclear units with different designs and different ages have had difficulty meeting these rules and have sought exemptions to them. In 2004, NRC began to encourage the nation's 104 nuclear units to transition to a less prescriptive, risk-informed approach that will analyze the fire risks of individual nuclear units. GAO was asked to examine (1) the number and causes of fire incidents at nuclear units since 1995, (2) compliance with NRC fire safety regulations, and (3) the transition to the new approach. GAO visited 10 of the 65 nuclear sites nationwide, reviewed NRC reports and related documentation about fire events at nuclear units, and interviewed NRC and industry officials to examine compliance with existing fire protection rules and the transition to the new approach.

What GAO Found

According to NRC, all 125 fires at 54 of the nation's 65 nuclear sites from January 1995 through December 2007 were classified as being of limited safety significance. According to NRC, many of these fires were in areas that do not affect shutdown operations or occurred during refueling outages, when nuclear units are already shut down. NRC's characterization of the location, significance, and circumstances of those fire events was consistent with records GAO reviewed and statements of utility and industry officials GAO contacted. NRC has not resolved several long-standing issues that affect the nuclear industry's compliance with existing NRC fire regulations, and NRC lacks a comprehensive database on the status of compliance. These long-standing issues include (1) nuclear units' reliance on manual actions by unit workers to ensure fire safety (for example, a unit worker manually turns a valve to operate a water pump) rather than "passive" measures, such as fire barriers and automatic fire detection and suppression; (2) workers' use of "interim compensatory measures" (primarily fire watches) to ensure fire safety for extended periods of time, rather than making repairs; (3) uncertainty regarding the effectiveness of fire wraps used to protect electrical cables necessary for the safe shutdown of a nuclear unit; and (4) mitigating the impacts of short circuits that can cause simultaneous, or near-simultaneous, malfunctions of safety-related equipment (called "multiple spurious actuations") and hence complicate the safe shutdown of nuclear units. Compounding these issues is that NRC has no centralized database on the use of exemptions from regulations, manual actions, or compensatory measures used for long periods of time that would facilitate the study of compliance trends or help NRC's field inspectors in examining unit compliance. Primarily to simplify units' complex licensing, NRC is encouraging nuclear units to transition to a risk-informed approach. As of April 2008, some 46 units had stated they would adopt the new approach. However, the transition effort faces significant human capital, cost, and methodological challenges. According to NRC, as well as academics and the nuclear industry, a lack of people with fire modeling, risk assessment, and plant-specific expertise could slow the transition process. They also expressed concern about the potentially high costs of the new approach relative to uncertain benefits. For example, according to nuclear unit officials, the costs to perform the necessary fire analyses and risk assessments could be millions of dollars per unit. Units, they said, may also need to make costly new modifications as a result of these analyses.