This section discusses U.S. commercial nuclear power reactors, NRC’s approach to natural hazard assessments, NRC’s endorsement of PRA, and actions NRC has taken on natural hazard assessments since the Fukushima Daiichi disaster. Currently, 104 commercial nuclear power reactors operate in the United States. Together, these reactors generated almost 20 percent of our nation’s electricity in 2011. These reactors are located at 65 power plants across the country (see fig. 1) and are operated by 26 different companies. All 104 operating reactors received their construction permits in the 1960s and 1970s, with most receiving their operating licenses in the 1970s and 1980s. Many reactors are reaching or have reached the end of their initial 40-year license. As of March 2012, NRC had renewed 71 reactor licenses for an additional 20 years and was currently reviewing 11 license renewal applications.reactors in Georgia in February 2012 and two new reactors in South Carolina in March 2012 and is considering 10 applications for the building and operation of new commercial nuclear power reactors. In March 2011, NRC chartered a staff task force to review its processes and regulations in light of the Fukushima Daiichi disaster and to recommend whether NRC should make near-term improvements to its The task force issued its final report in July 2011. regulatory system.Among other things, the task force found that NRC regulations and guidance provide a robust approach for assessing natural hazards, but it noted that NRC’s processes for assessing natural hazards had evolved over time. As a result, the licensing bases, design, and level of protection from natural hazards differ among operating reactors depending on when the reactors were built and when they were licensed for operation. Based on these findings, the task force recommended, among other things, that NRC order licensees to reevaluate the seismic and flooding hazards at their sites against current NRC requirements and guidance and, if necessary, update their reactor design bases. The task force further recommended that NRC initiate rulemaking to require licensees to confirm seismic and flooding hazards every 10 years, address any new and significant information and, if necessary, update their reactor design bases. In addition, the task force recommended that, while these longer term actions are being completed, NRC order licensees to check their seismic and flood protection features to identify and address any plant- specific vulnerabilities and verify the adequacy of monitoring and maintenance for protection features such as watertight barriers and seals. In response to the task force report, in August 2011, NRC directed agency staff to identify the task force recommendations that could and, in the staff’s view, should be implemented without unnecessary delay. The staff submitted a report to NRC in October 2011 with their proposed prioritization of the recommendations. In this report, the staff recommended that NRC move forward with requiring licensees to reevaluate the seismic and flooding hazards at their sites and to check their seismic and flood protection features. However, the staff recommended that NRC wait to initiate rulemaking requiring licensees to confirm their sites’ seismic and flooding hazards every 10 years in order to gain experience from the implementation of the initial reevaluation. In December 2011, NRC approved the staff’s proposals and supported actions on several recommendations. That same month, Congress passed, and the President signed, the 2012 Consolidated Appropriations Act, which included a provision directing NRC to require that licensees reevaluate external hazards at their sites, including seismic and flooding hazards, as expeditiously as possible. In February 2012, NRC staff proposed issuing a request for information that, among other things, would ask licensees to reevaluate the seismic and flooding hazards at their sites. The staff suggested PRA as one of two acceptable methods for licensees to use in reevaluating seismic hazards. The staff did not exclude, but also did not suggest, PRA as a method for assessing flooding hazards because, according to NRC officials, NRC currently uses a deterministic approach for assessing flooding hazards. NRC staff also proposed addressing other natural hazards, such as wind and missile loads from tornados and hurricanes, at a later date once sufficient resources are available for the reevaluations. According to NRC officials, it is not clear yet whether agency staff will suggest licensees use PRA or other methods to reevaluate those other natural hazards. In March 2012, NRC issued the request for information proposed by agency staff in February. Licensees and NRC apply PRA to natural hazards at operating U.S. nuclear power reactors to a limited extent, according to information provided by nuclear power industry representatives, NRC officials, and several experts in assessing nuclear reactor risks that we interviewed and data we obtained. While NRC has endorsed PRA as a means to enhance and extend traditional deterministic assessments, the agency has not conducted the analyses to determine whether or not it should require licensees of operating reactors to develop and maintain PRAs that address natural hazards. Nuclear power industry representatives, NRC officials, and several experts in assessing nuclear reactor risks we interviewed, as well as data we obtained, indicate that licensees and NRC apply PRA to natural hazards at operating nuclear power reactors to a limited extent. Prior to its response to the Fukushima Daiichi disaster, the last time NRC requested licensees to assess natural hazards was in 1991 when the agency initiated the IPEEE program. For the IPEEE, NRC requested each licensee to voluntarily identify and report plant-specific vulnerabilities to severe accidents caused by external events, including natural hazards. Although PRA was suggested by NRC as one of several possible methods for licensees to use in their examinations, most licensees opted to use methods other than PRA. Specifically, NRC received 70 IPEEE submissions from licensees covering all operating reactors. According to NRC’s summary of the 70 submissions, about 40 percent applied PRA to seismic hazards, and about 15 percent applied PRA to high winds, floods, and other external events. NRC reported that almost no licensees identified vulnerabilities with respect to seismic hazards, and none identified vulnerabilities related to high winds, flooding, or other external events. Nonetheless, according to NRC’s summary, 70 percent of the IPEEE submissions identified plant improvements related to seismic hazards, and about 50 percent identified plant improvements related to high winds and flooding. NRC performed a review of all IPEEE submissions to assess the technical adequacy of the methods and data used and noted that the quality of licensees’ submissions varied. NRC did not attempt to verify or validate licensees’ results. NRC staff proposed in 2011 that licensees reevaluate seismic hazards under the agency’s Generic Issue-199 program. Similar to the IPEEE, the proposal cited PRA as one—but not the only—possible method for assessing seismic hazards. The NRC staff has now proposed to pursue the reevaluation of seismic hazards as part of the implementation of the Fukushima Daiichi task force recommendations and has identified PRA as one of the methods that licensees can choose to use. Nuclear Energy Institute representatives told us that, if data were to be collected on licensees’ current application of PRA to natural hazards, they believe the data would likely show little difference since the IPEEE in the 1990s. They also stated that they believe few of those PRAs developed for the IPEEE would have been updated since then. Likewise, senior NRC officials told us that were NRC to obtain current data on licensees’ application of PRA to natural hazards, the results would likely show limited application, substantial variability, and few new or updated assessments since the IPEEE. According to several experts in assessing nuclear reactor risks we spoke with, few of the nation’s operating reactors currently have PRAs in place that address natural hazards. For example, one expert stated that some reactors have PRAs that address seismic hazards, and a few have PRAs that address external floods, but the rest do not have PRAs that address natural hazards at all. NRC does not collect comprehensive data on the extent of licensees’ voluntary application of PRA to natural hazards at operating reactors. NRC officials stated that, because PRAs are not required for operating reactors, NRC does not have comprehensive data on their use. NRC officials told us that where licensees voluntarily undertake risk-informed applications or license amendments, the information licensees submit to NRC may include results on natural hazards. For example, when a licensee chooses to use a risk-informed approach to request a change to its licensing basis, the licensee must determine whether natural hazards are a significant contributor to risk and provide that information to NRC. To make this determination, the licensee may use a PRA. Apart from these circumstances, however, NRC does not have data on operating reactor licensees’ PRA use. NRC officials could not tell us, therefore, which licensees of operating reactors have voluntarily undertaken PRAs that address natural hazards, what natural hazards are addressed, when existing PRAs were first developed and last updated, or the extent to which they meet NRC-endorsed quality standards. Nuclear Energy Institute representatives similarly told us that they do not collect data on PRA use and do not have a plant-by-plant listing of which reactors have PRAs in place that address natural hazards. NRC officials said that they do not collect comprehensive PRA information because licensees of operating reactors are not required to have a PRA. Further, they told us that, if NRC decided to collect this information, the agency would likely issue a “generic communication”––NRC’s primary method of communicating information to licensees and interested stakeholders or requesting information from them. NRC officials told us that a generic communication to obtain comprehensive PRA information would take NRC a significant amount of time to develop and issue.