Nuclear Regulatory Commission: Oversight and Status of Implementing a Risk-Informed Approach to Fire Safety
Released: 2012-11-26T00:00:00


Highlights: section_title: Why GAO Did This Study
paragraphs: In 1975, a fire at a nuclear power plant damaged critical control cables and hampered operators' ability to monitor the status of the plant's reactor. NRC subsequently issued deterministic fire safety regulations for plants to follow, but differences in plant design, coupled with changes in NRC guidance, made it difficult for most plants to meet the regulations without seeking numerous exemptions. In 2004, NRC issued a regulation permitting plants to voluntarily transition to risk-informed fire protection requirements. This new approach mirrors NRC's efforts to adopt a more risk-informed regulatory approach to nuclear safety in general. In 2008, GAO reported on three key fire safety issues and recommended NRC take action to address them.

GAO was asked to examine (1) NRC's progress in resolving the long-standing fire safety issues raised in GAO's 2008 report at plants remaining under the deterministic approach and at those plants transitioning to the risk-informed approach; (2) the potential benefits of transitioning to a risk-informed approach and the basis for NRC's decision to make adoption of this approach voluntary; and (3) challenges, if any, in efforts to transition to a risk-informed approach in regulating fire safety. GAO reviewed documents; analyzed responses from operators at a nonprobability sample of 12 nuclear plants and from nine consultants or academic experts on fire safety issues and risk-informed regulations; and interviewed NRC, industry, and public interest group representatives.

GAO is not making recommendations in this report. NRC found the report to be accurate and complete.

section_title: What GAO Found
paragraphs: The Nuclear Regulatory Commission (NRC), together with plant operators, has made progress in resolving three fire safety issues raised in GAO's 2008 report by implementing GAO's recommendations or taking other actions. NRC implemented the recommendation on multiple spurious operations (malfunctions caused by fire that could cause safety-related equipment to malfunction) by issuing new guidance or requiring additional modifications at the 36 plants with 57 reactors operating under deterministic regulations. NRC did not implement the recommendations to address the effectiveness of fire wraps or the extended use of interim compensatory measures plants use instead of repairing or replacing damaged safety equipment; however, NRC did take some actions, including (1) evaluating and reporting on corrective actions plants used to mitigate safety concerns associated with fire wraps and (2) developing metrics to gauge the progress of NRC's staff in resolve underlying issues related to the extended use of compensatory measures.

According to NRC, plants transitioning to a riskinformed fire safety approach are continuing to resolve these issues through modifications and analyses required as part of the transition process. GAO visited two transitioning plants and observed examples of such modifications. According to NRC officials, plant operators, and others GAO spoke with, the riskinformed regulatory approach to fire safety offers benefits over the deterministic approach, but NRC made adoption of the risk-informed approach voluntary because it considers plants that meet deterministic requirements to be safe. NRC officials stated that the risk-informed approach (1) will provide plant operators with information to help them quantifiably reduce risk and with flexibility in areas that do not affect risk and (2) allow operators to more easily demonstrate compliance with simplified licensing requirements. According to some of the plant operators, consultants, and experts GAO spoke with, plants will improve their safety using the risk-informed approach. NRC considered mandating the riskinformed approach, but it did not do so because of uncertainties over whether the agency could determine if the approach could improve protection of health and safety enough to impose new regulations. NRC considers plants that meet deterministic requirements to be safe, including plants that do so through approved exceptions to these requirements; thus, it does not plan to further analyze whether the risk-informed approach should be mandatory.

Plant operators, consultants, and experts GAO spoke with identified three challenges that may affect NRC's transition schedule and the number of plants that ultimately transition to the risk-informed approach. First, transition costs have been higher than initially expected, and operators from all of the nontransitioning plants GAO contacted cited this as reason they are remaining under the deterministic approach. Second, according to some operators, consultants, and experts, the absence of fire data may hinder the development of realistic risk assessments and contribute to overly conservative NRC risk assessment guidance, potentially leading to a misallocation of resources. NRC and other stakeholders disagreed with this assessment. Third, few people have expertise in risk analysis and fire modeling, and some operators, consultants, and experts expressed concern that the need for such expertise could compete with other safety-related efforts. However, most consultants and experts GAO spoke with believed that the number of people with expertise will be sufficient to support the transition effort.

section_title: Letter
paragraphs: On March 22, 1975, a worker testing for air leaks within a building  housing a nuclear reactor at the Browns Ferry nuclear power plant in  Alabama inadvertently started a fire when the candle he was using ignited  nearby electrical cables. The fire burned for 7 hours and damaged cables  for electrical power, control systems, and instrumentation, and impaired  the reactor’s cooling systems. The fire also prevented plant operators  from monitoring the reactor’s status normally. In the years following this  event, the Nuclear Regulatory Commission (NRC), which licenses and  regulates nuclear reactors, worked to develop a regulatory approach to  fire safety, and in 1980 the agency promulgated fire safety regulations  (referred to as “Appendix R”) for licensed commercial nuclear power  plants that were operating prior to January 1, 1979. These regulations  establish the design requirements for nuclear reactors at commercial  power plants to mitigate the effects of a fire on power plant operators’  ability to shut down a reactor safely. Commercial nuclear power plants  that were licensed to operate on or after that date are not subject to these  regulations, but NRC included licensing conditions—which we refer to as  licensing requirements—that are similar to the regulations in each of the  newer plants’ operating licenses. These regulations and requirements are  considered to be prescriptive (referred to as “deterministic”). In this report,  we refer to Appendix R and these similar conditions for operating licenses  NRC issued since January 1, 1979, as the deterministic approach. The  deterministic approach, which NRC has also used to oversee nuclear  power plant safety in areas other than fire protection, establishes a  specific set of potential accidents, the consequences of which a nuclear  power reactor must be designed to prevent or mitigate to protect public  health and safety. It also establishes requirements for engineering safety  margins and quality assurance standards for the design, manufacture,  and construction of nuclear power reactors.

In the 1990s, NRC’s oversight of nuclear reactor safety began moving  from the deterministic approach to a risk-informed, performance-based  approach to regulatory decision making that was being implemented in  phases, according to NRC documents. Since 2000, NRC has worked with  the Nuclear Energy Institute, the National Fire Protection Association  (NFPA), and others to develop a new risk-informed, performance-based  fire safety regulation, which endorsed key aspects of a fire safety  standard issued by NFPA. (Hereafter, we will refer to the “risk-informed,  performance-based approach” as the “risk-informed approach.”) NRC  issued this risk-informed regulation in 2004; it represents an alternative  approach to the deterministic fire protection regulations. NRC has allowed  nuclear power plant operators to voluntarily adopt the fire protection  requirements in the new regulation or to continue to comply with the  deterministic fire safety regulations and licensing requirements. In 2005,  NRC initiated a pilot program at two nuclear power plants that  volunteered to transition to the risk-informed fire safety approach.

In June 2008, we reported on NRC’s oversight of fire safety at nuclear  power plants and described three long-standing fire safety issues facing  the agency and the nuclear industry. First, we reported that a fire at a nuclear power plant could cause short circuits resulting in multiple circuit  failures, known as multiple “spurious operations,” in systems needed to  safely shut down a plant’s nuclear power reactor. At the time of our  report, plant operators typically accounted only for spurious operations  that occur one at a time or in isolation from one another, although industry  tests conducted in 2001 demonstrated that spurious operations could  occur simultaneously or in rapid succession. Second, we reported that  NRC had not resolved uncertainty about the effectiveness of some types  of fire-protection barriers (known as fire wraps) used to protect cables that  are important for safely shutting down a nuclear reactor. Third, we  reported that some plant operators had used temporary measures that  that they could take without prior approval to compensate for equipment  that needs to be repaired or replaced (compensatory measures) for an  extended period of time rather than conducting needed maintenance, a  practice that could degrade nuclear fire safety. For example, some plants  had adopted fire watches, in which teams of plant employees are either  posted continuously in a single location in a plant or rove throughout the  plant to detect signs of fires. We reported that, at one nuclear power plant  we visited, plant operators used fire watches for more than 5 years  instead of replacing faulty seals to cover openings in structural barriers.  We made three recommendations to address these long-standing fire  safety issues, and we discuss actions NRC took to address them in the  report.

In this context, you asked us to follow up on our 2008 report on fire  safety. Our objectives were to provide information on (1) NRC’s progress  in resolving the long-standing fire safety issues raised in our 2008 report  at plants remaining under the deterministic approach and at those plants  transitioning to the risk-informed approach; (2) the potential benefits of  transitioning to a risk-informed approach and the basis for NRC’s decision  to make adoption of this approach voluntary; and (3) challenges, if any, in  efforts to transition to a risk-informed approach in regulating fire safety.

To obtain information on NRC’s progress in resolving the fire safety  issues raised in our 2008 report, we reviewed regulations, guidance  documents, and periodic reports from NRC and industry. In addition, we  interviewed officials from NRC and representatives from industry and  public interest groups. We also conducted semistructured interviews with  plant operators about conditions at a nonprobability sample of six plants  remaining under the deterministic fire safety approach and six plants  transitioning to the risk-informed fire safety approach to obtain information  about fire protection at both types of plants. Because the plants included  in our review are a nonprobability sample that we selected to represent a  mix of reactor types and ages, the information gathered from these plants  cannot be generalized to the entire population of plants, or the nuclear  power industry as a whole, but it does allow us to make qualified  comparisons between different groups of plants and to discuss issues  faced by each group. To obtain information on the potential benefits of  transitioning to a risk-informed approach and the basis for NRC’s decision  to make adoption of this approach voluntary, we reviewed NRC  regulations, standards, and guidance on risk-informed regulation,  probabilistic risk assessment and the use of fire modeling at nuclear  power plants. We reviewed industry guidance documents and policy  statements on the transition. We also conducted a semistructured  interview with a total of nine nuclear engineering consultants and  academic experts with previous or current experience in the nuclear  power industry—six nuclear engineering consultants currently employed  at private firms, one consultant currently employed at a Department of  Energy national laboratory, and two academic experts with experience in  conducting probabilistic risk assessment, fire modeling, or both. Officials  from NRC and the National Institute of Standards and Technology (NIST),  industry representatives, as well as operators of the 12 plants we  consulted, also provided their insights into the strengths and weaknesses  of the deterministic and risk-informed approaches to fire safety. We  conducted site visits to the two nuclear power plants that participated in  the pilot program for the risk-informed fire safety approach. To obtain  information on challenges, if any, in efforts to transition to a risk-informed  approach in regulating fire safety, we reviewed documentation related to  NRC’s decision to make the adoption of the risk-informed approach  voluntary. We reviewed NRC regulations, guidance, and policy  documents on the deterministic and risk-informed fire safety approaches.  We also summarized the results of our semistructured interviews with the  nine nuclear engineering consultants and academic experts we contacted  regarding their views on the benefits of the deterministic and risk- informed approaches to fire safety. We also attended relevant  presentations at NRC’s March 2012 Regulatory Information Conference,  and we observed multiple NRC public meetings with industry concerning  issues related to the risk-informed approach to fire safety. Appendix I  presents a more detailed description of our scope and methodology, and  appendix II lists the names and affiliations of the nine consultants and  experts we interviewed.

We conducted this performance audit from September 2011 to October  2012 in accordance with generally accepted government auditing  standards. Those standards require that we plan and perform the audit to  obtain sufficient, appropriate evidence to provide a reasonable basis for  our findings and conclusions based on our audit objectives. We believe  that the evidence obtained provides a reasonable basis for our findings  and conclusions based on our audit objectives.
subsections: section_title: Background
paragraphs: This section discusses the development of NRC’s fire safety regulations,  NRC’s adoption of risk-informed regulation, and the status of the nuclear  industry’s adoption of the risk-informed fire safety approach.
subsections: section_title: NRC’s Fire Safety Regulations
paragraphs: NRC’s deterministic fire safety approach and its risk-informed fire safety  approach contain requirements that plants’ fire protection programs have  defense-in-depth objectives in areas important to fire safety. Under both  approaches, plants must meet the following objectives: (1) prevent fires  from starting; (2) detect rapidly, control, and extinguish promptly those  fires that do occur; and (3) provide protection for structures, systems, and  components important to safety so that a fire that is not promptly  extinguished by the fire suppression activities will not prevent the safe  shutdown of the plant. The two approaches provide different methods for  plants to demonstrate defense-in-depth capabilities. According to NRC  officials and nuclear industry representatives, no fire since the Browns  Ferry fire in 1975 has threatened a U.S. nuclear reactor’s ability to safely  shut down.

NRC’s deterministic fire safety approach requires that power plant  operators ensure that at least one system of electric cables and  equipment is available to safely shut down a reactor if a fire occurs. To  meet requirements under the deterministic approach, these operators  must, among other things, separate redundant systems, either by  distance or fire resistant barriers, such as a fire resistant wall or floor, or  by a material (fire wrap) that protects important cables and, in some  cases, operators must install fire detection and automatic suppression  systems. The requirements also specify the amount of space between  redundant systems or how long fire barriers should be able to withstand   For example, fire barriers must also be able to withstand fire for at  fire. least 1 hour in areas with automatic fire suppression systems and fire  detectors or for at least 3 hours where such features are not present. If  these requirements are not met or if a redundant system required for  shutdown could be damaged by fire suppression activities or operation of  the fire suppression system, NRC requires an alternative dedicated  shutdown capability. Figure 1 shows the process a plant operator uses to  demonstrate fire safety compliance under the deterministic approach.

Specifically, the deterministic fire safety approach requires nuclear reactors to have at  least one redundant system of electric cables and equipment available to safely shut down  the reactor. When two systems are in the same area of a nuclear reactor building, the  regulations require that they be (1) separated horizontally by more than 20 feet with no  intervening combustibles or fire hazards and for the area to have fire detectors and  automatic fire suppression systems, or (2) separated by a fire barrier, such as a fireproof  wall or floor, or by a material (fire wrap) that can withstand fire for 3 hours, or (3) enclosed  by a fire barrier or material that can withstand fire for 1 hour and for the area to have fire  detectors and an automatic fire suppression system.   “Containment” refers to structures, systems, or components provided to prevent or mitigate the  release of radioactive materials.

A “radiant energy shield” is a device used to protect components from the effects of radiant heat  generated by a fire.

Over the years, NRC has approved exemptions or deviations from this  deterministic approach for units that could not meet the fire safety  requirements if the units could otherwise demonstrate the ability to safely  shut down. Plants follow the following processes, as applicable:

Exemption process. Under this process, plant operators could obtain  an exemption from the deterministic requirements if they could  demonstrate fire safety through methods or features other than those  explicitly stated in the regulations.

Deviation process. Some of the reactors that came online after NRC  had defined the deterministic approach still could not meet the  requirements. In such cases, NRC allowed operators to seek  deviations from their licensing requirements if they could demonstrate  an acceptable alternate approach to fire safety.

In part because of variations among plant designs and different  interpretations of fire safety regulations between industry and NRC, the  agency continued to issue updated guidance related to the deterministic  regulations, according to NRC and industry documents. However, in  2004, NRC reported that the processing of exemption and deviation  requests had placed a “significant” burden on the resources of the agency  and the nuclear industry. NRC also acknowledged that industry  representatives and some members of the public described the  deterministic requirements as an “unnecessary regulatory burden.” As of  April 2012, NRC had granted more than 900 exemptions and deviations  from the deterministic fire safety approach, according to NRC documents  and officials.

In response to charges that the processes for granting exemptions and  deviations under the deterministic approach were burdensome, NRC  issued a regulation in 2004 permitting plants to voluntarily transition to  risk-informed fire protection requirements. Under this approach, a plant  operator adopts performance goals, objectives, and criteria for fire safety  that are defined by the fire protection standard issued by NFPA. The  operator can use probabilistic risk assessments (PRA) and fire models,  among other tools, to meet the performance criteria. A PRA is a  systematic assessment of what can go wrong, its likelihood, and its  potential consequences to determine quantitative estimates of a particular  risk, such as a fire safety risk. Fire models are mathematical predictions  of fire growth, environmental conditions, and potential effects on  structures or systems. Figure 2 illustrates how a plant demonstrates fire  safety compliance under the risk-informed approach.

Nuclear power plant operators can choose to make a transition from  using the deterministic approach to the risk-informed approach. In doing  so, they can conduct a PRA that is subsequently reviewed by teams of  experts from other plant operators and consulting firms that are not  involved in developing the PRA under review. After the PRA is reviewed,  the transitioning plant requests that NRC amend the plant’s operating  license. NRC staff review the amendment request and, if necessary,  request additional information from plant operators and conduct audits of  transition documents to ensure that the plant has conducted the  necessary tasks. If NRC approves the license amendment request, it will  issue a final report evaluating the safety of the plant, after which the  transition is considered complete. According to NRC documents and  officials, the agency expects the approval process for each plant to take  about 2 years after the plant submits its request for a license amendment.

section_title: NRC’s Adoption of a Risk- Informed Approach
paragraphs: NRC’s change to a risk-informed approach to fire safety is part of a larger  NRC effort to move toward accepting or adopting a risk-informed  approach to nuclear safety in general. Examples are as follows.

In 1995, NRC issued a policy statement encouraging the increased  use of PRA in all regulatory matters to the extent supported by the  state of the art in PRA methods and data and in a manner that   complemented NRC’s existing deterministic approach and supported  NRC’s defense-in-depth philosophy.

In 2007, NRC issued regulations requiring applicants for combined  licenses for new nuclear power reactors to submit a description and  the results of a plant-specific PRA to NRC as part of their  applications. NRC also began requiring recipients of combined  licenses to develop, maintain, and periodically upgrade a plant- specific PRA. Among other things, NRC required the PRA to cover  initiating events––that is, events that can lead to a reactor accident— for which there are NRC-endorsed consensus standards for PRA.

In 2011, NRC commissioned a risk management task force to develop  a strategic vision and options for adopting a more comprehensive risk- informed, performance-based regulatory approach. In its April 2012  report, the task force identified goals and objectives that could be the  framework for NRC regulatory activities 10 to 15 years in the future  and addressed changes that would be needed to ensure that the  framework is implemented. The task force reported, “NRC has  recognized that purely deterministic and prescriptive approaches can  limit the flexibility of both the regulated industries and the NRC to  respond to lessons learned from operating experience and support  the adoption of improved designs or processes.” The task force went  on to recommend, among other things, “the goal to adopt risk- informed and performance-based approaches, where practical, should  continue and should be incorporated into the revised regulatory  framework.”

section_title: Status of Industry’s Adoption of the Risk- Informed Fire Safety Approach
paragraphs: According to NRC documents, the 65 commercial nuclear power plants  operating in the United States house 104 reactors that incorporate 80  different designs. Furthermore, operators for 47 of these reactors, located  at 29 plants, plan to or are in the process of transitioning to the risk- informed approach to fire safety. NRC has adopted a staggered schedule  for such plants to submit license amendment requests seeking approval  to transition to the risk-informed approach. This schedule anticipates that  the agency will receive amendment requests from all of the plants by  2014 and will decide on all of the requests by 2016. (Appendix III contains  a list of transitioning plants and the dates they are scheduled to submit  their license amendment requests to NRC.) According to NRC officials,  the agency has implemented a discretionary enforcement policy under  which inspection findings related to the transition will not automatically  result in violations or penalties. The period of enforcement discretion is  tied to each plant’s committed date for submitting its license amendment  request and, according to NRC documents, provides incentive for plants  to adhere to their transition schedule. Plants that elect not to complete the  transition process must then seek exemptions or deviations or conduct  the modifications necessary to comply with the deterministic approach.

To assist the transition process, operators at two plants—including a plant  with three reactors in South Carolina and a plant with one reactor in North  Carolina—participated in a pilot program for the risk-informed approach.  These plants began the transition in August 2005 and, by December  2010, both plants had completed it. In 2011, NRC issued a report on  lessons learned from the pilot experience for other plant operators  interested in making the transition. Figure 3 shows the location of the 65  power plants and identifies those with nuclear reactors that will transition  to the risk-informed approach and those that remain under the  deterministic approach.

section_title: NRC Has Taken Steps to Resolve Long- standing Fire Safety Issues
paragraphs: NRC, in conjunction with plant operators, has made progress in resolving  the three long-standing fire safety issues raised in our 2008 report at  nuclear power plants remaining under the deterministic approach and  those transitioning to the risk-informed approach. NRC implemented one  of our three recommendations and took actions to resolve issues we had  identified in making the other two recommendations but did not  specifically implement these recommendations.

For the plants remaining under the deterministic approach, NRC has  done the following in response to our 2008 recommendations:

We recommended that NRC commit to a specific date for developing  guidelines that reactors should meet to prevent multiple spurious  operations. In November 2009, NRC issued a document in which it  endorsed industry guidance for methodologies that operators might  use to mitigate multiple spurious operations that could occur because  of a fire.  NRC also set a November 2012 deadline for power plant  operators to implement this guidance. Furthermore, as part of this  mitigation effort, NRC required corrective actions at the 36 plants that  have a total of 57 reactors remaining under deterministic regulations  (hereafter referred to as nontransitioning plants). Information  gathered by industry, as well as statements to us by selected plant  operators, indicate that most operators expect to implement the  guidance by NRC’s deadline. According to a January 2012 industry  survey of operators at plants housing 46 of the 57 nontransitioning  reactors, seven of the responding operators reported that they did not  expect to mitigate the effects of multiple spurious operations by the  deadline; the plants where these operators work at were not identified.  We subsequently interviewed operators at 6 nontransitioning plants,  and operators at 4 of these plants told us they expect to resolve  issues associated with multiple spurious operations by NRC’s  deadline. Operators at the fifth plant told us that an unexpected  maintenance period requiring the plant to go off-line pushed back their  mitigation of multiple spurious operations until its next maintenance  period, which will occur after November 2012; operators at the sixth  plant told us that their efforts to resolve other safety-related issues  may delay their mitigation of multiple spurious operations until 2014.  In August 2012, NRC officials told us that they may issue a generic  letter requesting information from plant operators regarding the  specific actions taken to mitigate multiple spurious operations  because, under current guidance, operators are not required to  provide such information unless requested during NRC plant  inspections.information on the methodologies plants are using to mitigate multiple  spurious operations, including any instances in which plants are using  methodologies not endorsed in NRC’s guidance document. The NRC  officials told us that the information request must go through NRC’s  review process and public comment period, and that they did not  expect that it would be released until November 2013 at the earliest.  These officials stated that the information request could result in the  need for additional work by licensees to fully mitigate multiple  spurious operations.

NRC, NUREG-1924, “Electric Raceway Fire Barrier Systems in U.S. Nuclear Power  Plants” (Washington, D.C.: May 2010). plants we interviewed told us that they have deficient fire wrap in their  plants but have resolved the associated safety issues through  modifications approved by NRC or by obtaining exemptions from  deterministic requirements. According to these plant operators, they  have done so by demonstrating to NRC that other safety features  compensate for the wraps, such as by installing upgrades to the  wraps to meet deterministic requirements, or by conducting  additional testing to demonstrate that the wraps are adequate as  configured in the plants.

NRC did not implement our recommendation that it address safety  concerns related to extended use of interim compensatory  measures but, in April 2009, the agency reported that it had  committed its staff to resolving the issues that underlie the need for  compensatory measures and developing metrics to gauge the  progress of this effort. Beginning in 2009, NRC and the Electric Power  Research Institute gathered data from nontransitioning plants on the  use of “long-term compensatory measures”—measures that have  been in place for longer than 18 months. NRC reported that the total  number of areas within plants where long-term compensatory  measures are used increased from June 2011 through December  2011. NRC officials stated their belief that the current use of extended  interim compensatory measures is associated with plant operator  efforts to mitigate multiple spurious operations, but that they had not  conducted an analysis to confirm this. Operators of five of the six  nontransitioning plants we contacted told us that they had  implemented interim compensatory measures while they work to  mitigate multiple spurious operations. NRC officials told us in April  2012 that they expected that the number of long-term compensatory  measures would decline following NRC’s deadline for mitigating  multiple spurious operations by November 2012. However, NRC  officials informed us in August 2012 that they were no longer certain  that the number of long-term interim compensatory measures would  decline as expected. According to these officials, the agency’s  planned information request related to multiple spurious operations  could potentially uncover issues that would require operators to  perform additional work to mitigate spurious operations. If this occurs,  the NRC officials told us, operators may need to use additional  extended compensatory measures at nuclear power plants as they  work to finally mitigate these issues after the information request is  released as planned in November 2013.

For the plants transitioning to the risk-informed approach to fire safety,  NRC officials and plant operators told us that they are continuing to  resolve the fire safety issues through modifications and analyses required  to comply with the risk-informed approach. Following are examples.

At one of the transitioning plants we visited, operators showed us a  new control facility that is being developed to shut down the plant’s  reactors from a separate building if a fire affects the primary shutdown  circuits. Such a capability allows the plant to mitigate multiple spurious  operations at a reactor.

At that same transitioning plant, operators told us that the  modifications and their use of PRA will eliminate their use of long-term  compensatory measures, which predominately consisted of fire  watches.

At a plant we visited that had completed the transition, operators  stated that they had significant amounts of degraded fire wrap but had  made upgrades to areas where the fire wrap was located, including  adding additional fire detection devices. Figure 4 shows an example  of a fire detection device—called an incipient fire detector alarm— installed at this plant in an area with degraded fire wrap to comply with  the risk-informed approach. According to industry documents, the  device detects combustion particles that overheating electrical cables  produce before any smoke, flames, or heat. An operator at this plant  told us that the PRA and other analysis performed as part of the  transition had demonstrated that the wrap, in conjunction with  upgrades, provide sufficient protection.

section_title: Benefits Cited in the Risk-Informed Fire Safety Approach, but NRC Considers Plants That Meet the Deterministic Approach to Be Safe
paragraphs: The risk-informed regulatory approach to fire safety offers benefits over  the deterministic approach, according to NRC documents we reviewed,  and NRC officials, consultants and experts, plant operators, and industry  representatives we spoke with, but NRC made the adoption of the risk- informed approach voluntary instead of mandatory because it considers  plants that meet deterministic requirements to be safe. NRC officials  stated that plant operators will have greater knowledge of plant risk and  simpler licensing conditions under the risk-informed approach, and some  consultants, experts, and power plant operators we interviewed stated to  us that the approach improves plant safety. NRC ultimately elected to  make the transition voluntary because of uncertainty over whether agency  staff could make the required determination regarding the approach’s  protection of health and safety to impose new requirements. NRC  considers plants that meet deterministic requirements to be safe,  including plants that do so through approved exemptions and deviations.
subsections: section_title: NRC Officials, Plant Operators, and Consultants and Experts Cited Various Benefits of the Risk-Informed Approach
paragraphs: NRC documents and agency officials identified two major benefits of  transitioning to the risk-informed approach. First, according to NRC  officials, the modifications and risk assessments that plant operators  perform as part of the transition process will help them identify and devote  resources to activities that quantifiably reduce risk while allowing them  greater flexibility in areas that do not significantly affect risk. For example,  in its April 2012 risk management task force report, NRC stated that the  risk-informed approach includes performance-based methods for  evaluating plant configurations that would not meet the deterministic  requirements, and that these methods allow engineering analyses to  demonstrate that changes in overall plant risk that result from these plant  configurations are acceptably small and that fire protection defense-in- depth is maintained. To illustrate the difference between the risk- informed and deterministic approaches, NRC officials told us that, in  2008, operators of a nontransitioning plant notified NRC that they had  found 17-½ feet of separation between safety systems in a single area,  rather than at least 20 feet as required by deterministic regulations. The  plant had to submit an exemption request—which NRC approved 8  months later—for what NRC officials characterized as a possibly minor or  nonexistent safety issue. These officials told us that obtaining a single  exemption—which could include engineering assessments or other work  to demonstrate safety—could cost a plant tens of thousands of dollars.  According to NRC documents, if the agency does not approve an  exemption, a plant could be required to make safety-related modifications  that are more expensive than obtaining an exemption but that do not  quantifiably reduce risk. Operators from all six of the transitioning plants  we contacted said they expected that the risk-informed approach would  allow them to avoid making expensive modifications or seeking  exemptions to comply with deterministic guidelines. According to NRC  guidance and other information provided to us by NRC officials, the  approach would also allow plant operators to have the flexibility to change  aspects of their approved fire protection programs for reasons other than  fire safety concerns—such as administrative controls, maintenance  procedures, and physical plant modifications if they wished to do so— without prior NRC review and approval if those modifications would not  increase risk beyond a certain threshold. An NRC official told us that he  was not aware of any operator of a plant meeting deterministic rules  making the changes listed above for any reason.

Second, according to NRC officials, under the risk-informed approach,  plant operators can obtain licensing amendments that correspond to a  single fire safety standard issued by NFPA, rather than be subject to the  dozens of guidance documents, communications, and regulatory issue  summaries that NRC has issued under the deterministic approach. NRC  officials— including regional inspectors responsible for conducting fire  safety inspections—told us they expect that simplified licensing  requirements will enable plants to more easily demonstrate compliance  and allow NRC inspectors to focus on technical issues significant to risk  rather than on reading and interpreting complex licensing documents  before conducting plant inspections. Operators from two of the six  transitioning plants we contacted cited the prospect of clarifying or  simplifying their license requirements as a major factor in their decision to  adopt the risk-informed approach. For example, under this approach,  operators at one plant expected to resolve long-standing issues dating  from the 1980s, including differences in interpretation by the plant  operator and NRC on how to implement deterministic requirements.

An NRC webpage updated in March 2012 states that the adoption of the  risk-informed approach “can absolutely improve an already safe operating  environment…  fire risk analysis and fire science has evolved in the  last two decades, and we now know how to make already safe plants  safer.” The webpage also notes that early fire protection regulations were  developed without the benefit of quantitative estimates of risk and before  recent advances in performance-based methods such as fire modeling. / yr for LERF . The proposed change must  also be consistent with the defense-in-depth philosophy and must maintain sufficient  safety margins. The change may be implemented following completion of the plant change  evaluation.

Operators from the six transitioning plants and five of the nine consultants  and experts we contacted said that they believed that transitioning plants  will be safer than they were under the deterministic approach. Operators  at the six transitioning plants said that the transition has improved plant  safety because of the extensive fire safety analyses or modifications  required during the transition process. For example, operators at one  plant stated that they had added fire detection capabilities and that  through safety analysis were able to determine that actions that operators  were required to do manually in 70 areas throughout the plant to ensure  safe shutdown under the deterministic approach were not needed. At the  time of our review, the plant operators had yet to submit their license  amendment request to NRC, and the agency had not formally evaluated  the plant’s safety analysis.

section_title: NRC Made the Risk- Informed Approach Voluntary Because It Considers Plants Meeting Deterministic Regulations to Be Safe
paragraphs: NRC officials told us that the agency considers plants that meet  deterministic requirements to be safe and, therefore, it decided not to  require these plants to transition to the risk-informed approach.  Furthermore, as we previously noted, under the deterministic approach  there has not been a fire at a U.S. plant that has prevented a plant’s  reactor from safely shutting down. Also, in the late 1990s, NRC  conducted an analysis of selected plants and determined that the  cumulative effects of multiple exemptions at plants under the deterministic  approach did not pose a significant risk.

NRC, Development of a Risk-Informed, Performance-Based Regulation for Fire  Protection at Nuclear Power Plants, SECY-98-058 (Washington, D.C.: March 1998). This  document outlines three options that NRC staff considered, with industry input, related to  adopting a risk-informed approach. regulation or to maintain the existing deterministic framework without  adopting risk-informed regulation. According to the policy statement, NRC  staff recommended to allow plant operators to either voluntarily adopt the  risk-informed approach or remain under the deterministic approach  because it was unclear at that time whether NRC staff would be able to  determine if the risk-informed approach improved safety over the  deterministic approach. Such a determination would be needed for NRC  to comply with its “backfit rule.” Under this rule, NRC is generally  prohibited from imposing new regulatory requirements on plants unless it  determines that the requirements (1) are necessary to provide adequate  protection to the health and safety of the public; (2) are necessary to bring  a facility into compliance with a license or the agency’s rules or orders, or  into conformance with plant operators’ written commitments; or (3) would  substantially increase protection of public health and safety and the  implementation costs would be justified in view of the increased  protection. The NRC commissioners subsequently directed the staff to  proceed with rulemaking to make adoption of the risk-informed approach  voluntary. Similarly, in 1998, NRC staff recommended that the  implementation of revised regulations pertaining to a wide range of  reactor operations should be voluntary.it would be difficult to make the backfit determination needed to require  mandatory implementation and further stated that doing so could create  the impression that plants operating under the current regulations were  less safe. Ultimately, the NRC commissioners determined that  compliance would be voluntary.

GAO, Nuclear Regulatory Commission: Natural Hazard Assessments Could Be More  Risk-Informed, GAO-12-465 (Washington, D.C.: Apr. 26, 2012). to determine whether a new requirement should be implemented.  Similarly, NRC officials we interviewed stated that conducting a backfit  analysis for fire safety approaches requires extensive staff resources.  These officials told us that plants that meet the deterministic  requirements—including those that do so through approved exemptions  or deviations—are considered by definition to be safe in that they provide  a reasonable assurance of adequate protection. Therefore, the agency  does not plan to consider further the need for a mandatory adoption of the  risk-informed approach.

section_title: Plants Transitioning to the Risk-Informed Approach Face Three Key Challenges
paragraphs: NRC documents we reviewed and some of the plant operators, industry  representatives, consultants and experts we spoke to identified three  primary challenges that may affect plants’ ability to transition to the risk- informed approach by 2014, when NRC expects to have received  requests for license amendments from all of the plants that have currently  committed to make the transition. These challenges may also limit the  number of plants that ultimately transition to the risk-informed approach  beyond those that have already committed to doing so.

First, transition costs have been higher than expected. Operators from 7  of the 12 plants we contacted told us that initial estimates for costs and  resources for transition activities were relatively low (from several  hundred thousand dollars to a few million dollars for each plant), and  these estimates were based on projections that the activities could be  conducted relatively easily. As information from the pilot program became  available, however, cost estimates began to rise, according to plant  operators we spoke with. For example, operators from one pilot plant told  us that they had originally estimated transition costs of $5 to 10 million,  but ultimately the plant spent $20 million because plant operators  identified the need for more modifications than planned, and conducting  the PRA was more costly than expected. Operators from all of the  nontransitioning plants we contacted cited the cost of the transition as a  reason why they are remaining under the deterministic approach, and five  of the nine consultants and experts we spoke with stated that cost was a  basis for plants not to transition to the risk-informed approach.

According to the lessons learned report prepared by NRC staff after the  two pilot plants completed the transition, both NRC and industry  representatives underestimated the complexity of the analyses and level  of resources needed for the pilot plants to transition to the risk-informed  approach. NRC officials told us that none of the currently transitioning  plants have officially informed the agency why their transition costs have  been higher than expected, but that the officials believe that many of the  plant operators did not know the precise location of important cables in  their plants; thus, they had to spend substantial resources to pinpoint the  location of the cables before conducting their PRA. NRC’s risk  management task force characterized the transition in its 2012 report as a  “high-cost, high-payback” endeavor. The task force also acknowledged  the high cost of developing high-quality PRAs and implementing fire  protection changes; nevertheless, it stated that the cost of the  alternative—continuing with the deterministic approach or allowing plants  to shut down—is “even more prohibitive” for the industry. Moreover, one  plant operator—whose plant was not involved in the pilot program— stated that the results of the pilot program confirmed his plant’s original  decision not to commit to the transition process.

Second, it may be difficult to develop realistic PRAs, according to industry  documents and some of the plant operators, consultants, and experts we  interviewed. Five of the nine consultants and 5 of the 12 plant operators  we contacted expressed concern that NRC’s guidance for fire PRAs  produces overly conservative results. Some of these individuals said that  the assumptions underlying the guidance suggest that damage caused by  fire is much more likely to occur than has actually been observed in  nuclear power plants and that overly conservative risk assessments could  cause plant operators to misallocate the resources available to reduce  risk of fire. According to 4 of the 12 plant operators and two of the nine  consultants and experts who discussed this issue with us, the specific  reason for overly conservative PRAs is that sufficient data are not  available to develop realistic calculations supporting fire models and  PRAs because no major fire incidents—in which a fire threatens a plant’s  ability to safely shut down—have occurred at nuclear power plants since  the 1975 Browns Ferry fire. These individuals stated that, in the absence  of sufficient data, NRC and its consultants used overly conservative  assumptions in developing NRC’s guidance for conducting PRAs. NRC  officials and two of the consultants we spoke with agreed that some  aspects of NRC’s guidance are conservative, but not overly so. These  consultants stated that overly conservative risk assessments could result  from plant operators’ incorrect application of fire modeling, rather than  conservative guidance by NRC. NRC is scheduled to release new  guidance for fire modeling in October 2012 that is intended to help plant  operators identify how to apply such modeling correctly. In addition, NRC  officials told us that they are working with industry to identify areas where  NRC’s PRA guidance can be improved as more fire data become  available from ongoing research.

Third, the number of people experienced in fire modeling and probabilistic  risk assessment is relatively small compared with the potential need,  according to plant operators, consultants, and experts we spoke with.  These individuals differed on the extent to which the number of experts in  the field would affect the transition effort. The experts needed to help with  the transition include consultants who develop risk assessments and fire  models for transitioning power plants, peer reviewers commissioned by  industry who review PRAs, and NRC employees or contractors who  assist in approving license amendments. Industry representatives we  spoke with characterized the PRA field as barely able to keep up with the  demands of the transition, and they noted that many individuals with  relevant expertise are nearing retirement age. In addition, we identified  only three universities that support accredited degree programs in fire  protection engineering in the United States.

We have reported on the challenge posed by the limited number of  consultants for conducting PRAs as far back as 1985. For example, in  June 2008, we noted that numerous NRC officials, industry  representatives, and academic experts expressed concern about the  limited number of personnel with the necessary skills and training to  develop and review PRAs. More recently, in April 2012, we reported that  experts in PRAs had said that a key challenge to the use of these  assessments is the limited number of experts qualified to develop  PRAs. We recognize that our April 2012 report discussed PRAs for  natural hazards and that fires in nuclear plants are not natural hazards,  but the same pool of individuals conduct PRAs for both types of risk. One  of the experts we consulted for our April 2012 report noted that finding  individuals with PRA expertise has become more difficult because NRC  and industry are conducting PRAs for natural hazards in response to the  Fukushima Daiichi nuclear power plant disaster. For this review,  operators at 5 of the 12 plants we interviewed expressed concern about  the limited numbers of individuals skilled in PRA and the effect that these  numbers may have on plant costs and PRA quality. Operators at one  plant estimated that they had paid twice as much in contractor fees as  originally planned. Seven of the nine consultants and experts we  contacted acknowledged that the current demand for expertise could, in  the short term, limit the ability of PRA or fire modeling experts to meet all  of the needs of industry or NRC. For example, one expert observed that it  has been very difficult to get the number of experts needed to conduct  peer reviews of plants’ PRAs. However, six of the nine consultants and  experts stated that enough people with expertise will ultimately be  available to meet the modeling and review needs of both industry and  NRC to meet the transition schedule, in part because of increased  demand, training, and new practitioners entering the field. For its part,  NRC has taken some steps to manage resource needs, including  contracting with experts from the Department of Energy’s national  laboratories and obtaining additional staff for the NRC team responsible  for overseeing the transition. In October 2011, NRC identified the  transition effort as a high-priority safety activity that would not be delayed  by work related to the agency’s Fukushima response.

section_title: Agency Comments and Our Evaluation
paragraphs: We provided a draft of this report to the Chairman of the Nuclear  Regulatory Commission for review and comment.  NRC provided written  comments on October 12, 2012, stating that it found the draft report to be  accurate, complete, and appropriate in its handling of sensitive  information. NRC also provided technical comments, which we  incorporated into our report as appropriate. NRC’s comments are  reproduced in appendix IV.

As agreed with your offices, unless you publicly announce the contents of  this report earlier, we plan no further distribution until 30 days from the  report date. At that time, we will send copies to the Chairman of NRC, the  appropriate congressional committees, and other interested parties. In  addition, the report will be available at no charge on the GAO website at  http://www.gao.gov.

If you or your staff members have any questions about this report, please  contact me at (202) 512-3841 or ruscof@gao.gov. Contact points for our  Offices of Congressional Relations and Public Affairs may be found on  the last page of this report. Key contributors to this report are listed in  appendix V.

section_title: Appendix I: Objectives, Scope, and Methodology
paragraphs: Our review provides information on: (1) the Nuclear Regulatory  Commission’s (NRC) progress in resolving the long-standing fire safety  issues raised in our 2008 report at plants remaining under the  deterministic approach and at those plants transitioning to the risk- informed approach; (2) the potential benefits of transitioning to a risk- informed approach and the basis for NRC’s decision to make adoption of  this approach voluntary; and (3) challenges, if any, in efforts to transition  to a risk-informed approach in regulating fire safety.

For all of these objectives, we reviewed relevant literature and NRC  documents and interviewed NRC officials, representatives from the  nuclear power industry, consulting organizations, public interest groups,  and others to understand NRC’s efforts to oversee fire safety at nuclear  power plants. In addition, we summarized the results of semistructured  interviews from a nonprobability sample of operators of 12 nuclear power  plants—housing a total of 24 of the nation’s 104 nuclear reactors— to  obtain information about fire protection at plants that are remaining under  the deterministic approach, as well as those that are transitioning to the  risk-informed approach. Six of the plants we contacted are remaining  under the deterministic approach, and the remaining six plants plan to or  are in the process of transitioning to a risk-informed approach. These  plants were Arkansas Nuclear One in Arkansas, Braidwood Nuclear  Generating Station in Illinois, Browns Ferry Nuclear Plant in Alabama,  Catawba Nuclear Station in South Carolina, Comanche Peak Nuclear  Power Plant in Texas, Diablo Canyon Power Plant in California, Dresden  Generating Station in Illinois, Edwin I. Hatch Nuclear Plant in Georgia,  Indian Point Energy Center in New York, Joseph M. Farley Nuclear Plant  in Alabama, Nine Mile Point Nuclear Station in New York, and Wolf Creek  Generating Station in Kansas. We selected these plants to capture a  variety of characteristics, including whether they are transitioning to a  risk-informed approach to fire safety, the year their operating license was  issued, and reactor type. The information gathered from these plants  cannot be used to make inferences about the entire population of plants,  or the nuclear power industry as a whole, but it does allow us to make  qualified comparisons between different groups of plants and to discuss  issues faced by each group. We also visited two plants, housing a total of  four reactors, that participated in a pilot program for the risk-informed  approach to fire safety. These reactors are the Oconee Nuclear Station in  South Carolina and the Shearon Harris Nuclear Plant in North Carolina.

We also interviewed NRC officials from the Office of General Counsel,  Office of Nuclear Regulatory Research, the Office of Nuclear Reactor  Regulation (including the team overseeing the transition of plants to the  risk-informed fire safety approach), as well as NRC officials in Region II  and Region IV. We also interviewed officials from the National Institute of  Standards and Technology regarding their development of fire models  used at nuclear power plants and their role in providing modeling and  experimentation expertise in NRC’s evaluation of fire models.  Furthermore, we interviewed representatives from the Nuclear Energy  Institute, the Union of Concerned Scientists, Beyond Nuclear, and NC  WARN to discuss their views on NRC’s oversight of fire safety at U.S.  nuclear power plants.

To obtain information on NRC’s progress in resolving the long-standing  fire safety issues raised in our 2008 report at plants remaining under the  deterministic approach and at those plants transitioning to the risk- informed approach, we reviewed relevant documents obtained from NRC  and selected plant operators related to NRC’s progress in resolving fire  safety issues raised in our 2008 report. We reviewed NRC and industry  guidance to plant operators on mitigating issues associated with multiple  spurious operations at plants remaining under the deterministic approach  to fire safety, as well as those transitioning to the deterministic approach  to fire safety. We also reviewed NRC reports and guidance on the use of  fire wraps at nuclear power plants and documentation on how operators  resolved issues associated with the use of fire wraps. We reviewed joint  NRC and industry periodic reports on the extended use of interim  compensatory measures at nontransitioning and transitioning plants.

To obtain information on the potential benefits of transitioning to a risk- informed approach and the basis for NRC’s decision to make adoption of  this approach voluntary, we reviewed relevant documents obtained from  NRC and industry on NRC’s efforts to transition to a risk-informed  approach to regulating fire safety at 29 plants. We reviewed NRC  regulations, standards, and guidance on risk-informed regulation,  probabilistic risk assessment (PRA), and the use of fire modeling at  nuclear power plants. We reviewed industry guidance documents and  policy statements on the transition. We also summarized the results of  semistructured interviews with nuclear engineering consultants and  academic experts with experience in PRA, fire modeling, or both. To  identify consultants and experts to interview, we conducted a review of  journal articles, prior GAO reports, NRC guidance documents, industry  conference publications, and congressional and NRC hearings. We then  solicited recommendations from NRC, the Nuclear Energy Institute, and  public interest groups on possible interview subjects. We also asked  consultants and experts we contacted for our initial interviews to identify  others whom we should interview. Out of a list of 23 potential interview  contacts, we ultimately selected a total of nine nuclear engineering  consultants and academic experts based on (1) the relevance of their  publications, testimony, and background to our review and (2) the extent  to which these individuals were recommended to us by NRC, industry  representatives, public interest groups, and their peers. Of these nine  individuals, six nuclear engineering consultants are currently employed by  private consulting firms, one nuclear engineering consultant is currently  employed by a Department of Energy national laboratory, and two  academic experts are currently employed by universities. Appendix II lists  the experts we interviewed.  We contacted these nuclear engineering  consultants or academic experts by telephone and e-mail, informed them  about the nature of our review, and requested their participation in our  semistructured interviews. The number of individuals with the relevant  expertise to address our questions is limited and, as a result, all of the  individuals we interviewed are currently working or have in the past  worked for or consulted with the nuclear industry or NRC. We conducted  a content analysis to assess experts’ responses to a standard set of  questions and grouped responses into overall themes. The views  expressed by experts do not necessarily represent the views of GAO. Not  all of the experts provided their views on all issues.

To obtain information on challenges, if any, in efforts to transition to a  risk-informed approach in regulating fire safety, we reviewed  documentation related to NRC’s decision to make the adoption of the risk- informed approach voluntary. We reviewed NRC regulations, guidance,  and policy documents on the deterministic and risk-informed fire safety  approaches, as well NRC’s 2012 risk management task force report and  other documentation related to the agency’s expected future use of risk  management principles in the regulation of nuclear safety. We reviewed  NRC inspection reports from plants that are remaining under the  deterministic approach to fire safety and those that are transitioning to a  risk-informed approach. We summarized the results of our semistructured  interviews with the nine nuclear engineering consultants and academic  experts we contacted regarding their views on the benefits of the  deterministic and risk-informed approaches to fire safety. We also  attended relevant presentations at NRC’s March 2012 Regulatory  Information Conference, and we observed multiple NRC public meetings  with industry concerning issues related to the risk-informed approach to  fire safety.

We conducted this performance audit from September 2011 to October  2012 in accordance with generally accepted government auditing  standards. Those standards require that we plan and perform the audit to  obtain sufficient, appropriate evidence to provide a reasonable basis for  our findings and conclusions based on our audit objectives. We believe  that the evidence obtained provides a reasonable basis for our findings  and conclusions based on our audit objectives.

section_title: Appendix II: List of Consultants and Experts Contacted for This Report

section_title: Appendix III: Schedule for Plants Transitioning to a Risk-Informed Approach to Fire Safety
paragraphs: Shearon Harris was a pilot plant for the risk-informed approach transition. NRC approved the plant’s  license amendment request on June 28, 2010.

Oconee was a pilot plant for the risk-informed approach transition.  NRC approved the plant’s license  amendment request on December 29, 2010.

On September 7, 2012, NRC notified Arkansas Nuclear One, Unit 2 that it did not accept the  reactor’s license amendment request, and the reactor is no longer under enforcement discretion.  Plant operators may resubmit an amendment request at an unspecified future date.

Arkansas Nuclear One, Unit 1 submitted an extension request to delay submittal of its license  amendment request to August  2013. NRC staff are currently reviewing the extension request.

Beaver Valley submitted an extension request to delay submittal of its license amendment request to  December  2013. NRC staff are currently reviewing the extension request.

Browns Ferry originally committed to submit its License Amendment Request in March 2012 but was  granted an extension by NRC to March 2013.

section_title: Appendix IV: Comments from the Nuclear Regulatory Commission

section_title: Appendix V: GAO Contact and Staff Acknowledgments
subsections: section_title: GAO Contact

section_title: Staff Acknowledgments
paragraphs: In addition to the individual named above, Kim Gianopoulos and Ernie  Hazera, Assistant Directors; Steve Carter; and Stephanie Gaines made  key contributions to this report. R. Scott Fletcher, Cindy Gilbert, Amanda  Manning, Armetha Liles, Cynthia Norris, Carol Herrnstadt Shulman,  Jeanette Soares, and Kiki Theodoropoulos provided technical assistance.


Question-summary annotations: questions: question: How well has NRC addressed their fire safety issues?
answer: The Nuclear Regulatory Commission (NRC), together with plant operators, has made progress in resolving three fire safety issues raised in GAO's 2008 report by implementing GAO's recommendations or taking other actions.
child_questions: question: How has the NRC implemented GAO's recommendations?
answer: NRC implemented the recommendation on multiple spurious operations (malfunctions caused by fire that could cause safety-related equipment to malfunction) by issuing new guidance or requiring additional modifications at the 36 plants with 57 reactors operating under deterministic regulations.

question: To what extent have they addressed fire wraps and compensatory measures?
answer: NRC did not implement the recommendations to address the effectiveness of fire wraps or the extended use of interim compensatory measures plants use instead of repairing or replacing damaged safety equipment; however, NRC did take some actions, including (1) evaluating and reporting on corrective actions plants used to mitigate safety concerns associated with fire wraps and (2) developing metrics to gauge the progress of NRC's staff in resolve underlying issues related to the extended use of compensatory measures.

questions: question: What is notable example of a fire safety concern?
answer: In 1975, a fire at a nuclear power plant damaged critical control cables and hampered operators' ability to monitor the status of the plant's reactor.
child_questions: question: What did the NRC to resolve the problems related to the fire?
answer: NRC subsequently issued deterministic fire safety regulations for plants to follow, but differences in plant design, coupled with changes in NRC guidance, made it difficult for most plants to meet the regulations without seeking numerous exemptions.

question: What new approaches has NRC since engaged?
answer: In 2004, NRC issued a regulation permitting plants to voluntarily transition to risk-informed fire protection requirements. This new approach mirrors NRC's efforts to adopt a more risk-informed regulatory approach to nuclear safety in general.

question: What is GAO's relationship to the issue of fire safety?
answer: This new approach mirrors NRC's efforts to adopt a more risk-informed regulatory approach to nuclear safety in general.