Individual Plant Examinations

CFR50.54(f) states that the licensee must submit individual plant examinations (IPE) of nificant. safety issues to justify continuing operation of a reactor facility. The NRC issued leric... 

The confluence of sharply rising Operations and Maintenance (O M) costs. NRC requested Individual Plant Examinations (IPEs) and increased personal computer capabilities gave rise to the R R Workstation. Its uses and maintains-current PSA models and databases for individual plants to perform O M planning and scheduling, and uses the PSA in IPE models to identify plant design, procedure and operational vulnerabilities. The Risk and Reliability Workstation Alliance was organized by EPRI to support the R R Workshop in order to achieve O M cost reduction, plant productivity and safety enhancement through risk-based, user-friendly, windowed software louls (Table 3.6 8). The Alliance, initiated in 1992, includes 25 U.S. utilities and four international partners from Spain, France, Korea, and Mexico. SAIC is the prime contractor for the R R Workstation, with participation of five other PSA vendors. 

Individual Plant Examinations (IPE) (NUREG-1560) were performed by the U.S. utilities using their staff and utilities. Results from the IPEs indicate that human error can significantly increase or decrease the CDF. Certain human actions are consistently important for BWRs and PWRs. 

On August 8, 1985, the U.S. Nuclear Regulatory Commission (NRCf requested the operators of nuclear power plants in the U.S. to perform Individual Plant Examinations (IPE) on their plants. IPEs are probabilistic analyses that estimate the core damage frequency (CDF) and containment performance for accidents initiated by internal events (including internal flooding, but excluding internal fire). Generic Letter (GL) 88-20 was issued to implement the IPE request to identify any plant-specific vulnerabilities to severe accidents and report the results to the Commission. ... 

Risk-based information provides a foundation for regulation of severe accidents. Early PRAs, with large uncertainties, indicated risk that was above or below the Safety Goals depending on containment performance. Consequently the NRC developed an Integration Plan for Closure of Severe Accident Issues (SECY-88-47) with six main elements to this plan 1) individual plant examinations (IPE), 2) containment performance improvements, 3) improved plant oper itions, 4) severe accident research, 5) external event considerations, and 6) accident management. 

Individual Plant Examination Program Perspectives in Reactor Safety and Plant Performance, 1996. 

Individual Plant Examinations Perspectives on Reactor Safety, PSA-96... 

In-6. Office of Nuclear Regulatory Research, Individual Plant Examination Program ... 

This report summarises results of the Individual Plant Examinations for 74 nuclear power plant sites in the USA. The Individual Plant Examinations all involved Level 1 probabilistic risk assessments. Some also included level 2 analyses. The report describes the ranges of core damage frequencies in terms of the plant and containment types. The report provides a good indication of the t3q)es of frequency dominant accidents that might have to be addressed in the development of accident management strategies. 

US NRC. 1988. Individual plant examination for severe accident vulnerabilities-10 CFR 50.54(f). Generic Letter 88-20, November 23. Available at http //www.nrc.gov/reading-rm/adams. html (accessed October 2, 2015). 

NUREG-1560, "Individual plant examination programme perspectives on reactor safety and plant performance". Draft report for comments, November 1996. 

NUREG-1407, "Individual plant examination of external events for severe accident vulnerabilities. ... 

A seismic PSA was performed in the Individual Plant Examination of External Event (IPEEE) programme in USA and in some other member states. It was shown in these programmes that the probability of core damage caused by an earthquake is of a comparable order as the core damage probability caused by internal events. 

The USNRC requested that each licensee perform an individual plant examination of external events (IPEEE) to identify vulnerabilities, if any, to severe accidents and report the results together with any licensee-determined improvements and corrective actions. 

NUREG-1335, Individual plant examination Submittal guide, USNRC, Aug. 1989. 

International Nuclear Safety Advisory Group (IAEA) individual plant evaluation individual plant examination of external event International Peer Review Service (IAEA)... 

The basic steps involved in an external flooding analysis are similar to those followed for internal flooding in the individual plant examination. However, the focus of attention is on areas, which due to their location and grading may be susceptible to external flood damage. This requires information on such items as dykes, surface grading, locations of structures and locations of equipment within the structures. It is expected that the generic envelope will bound site hazard parameters. 

PSA is a methodology that can be applied to provide a structured analysis process to evaluate the frequency and consequences of accidents scenarios in nuclear power plants. NRC first applied PSA in the Reactor Safety Study (NRC, 1975). An important initiative (NRC, 1988) was the issuance of Generic Letter GL-88-20, which originated the program known as IPE, Individual Plant Examination, NRC (1988). This is because the Reactor Safety Study did not consider each plant individually in the risk assessment. 

NRC (1988). Individual Plant Examination for Severe Accident Vulnerabilities—10 CFR 50.54(f). Generic Letter GL-88-20, Nuclear Regulatory Commission, Washington, DC, USA. 

The results of the new containment calculations have been compared back to the structural assessments performed by the licensee during the Individual Plant Examination study (1990s), and are... 

Past research has indicated the plant-specific nature of severe accident vulnerabilities. Therefore, the Severe Accident Policy stated the desirability of performing a systematic examination of each nuclear power plant in order to identify potential plant-specific vulnerabilities to severe accidents. Three years later, the NRC issued a generic letter (88-20) and guidance (NUREG-1335), which called for licensees to perform a systematic Individual Plant Examination (IPE) of each nuclear power plant operating or under construction. The stated purpose of the Individual Plant Examination was to have each utility ... 

The Individual Plant Examination Generic Letter makes it clear that a major benefit from this activity is the education of the utility staff in the area of severe accidents. The utilities are expected to perform much of the analysis in-house and not rely solely on consultants for performing the analysis. 

Individual Plant Examination results were to be reported to the NRC within three years according to guidance provided in NUREG-1335. The results of the Individual Plant Examinations that have been received are currently being reviewed by the NRC. These results will be used, in part, to deal with Unresolved Safety Issues and Generic Safety Issues. The Individual Plant Examination submittals will indicate whether particular issues apply to the plant and the utility s case for resolution. If vulnerabilities are found, the utility is to provide a plan and schedule for resolving the problem. 

U.S. Nuclear Regulatory Commission, Title 10 Code of Federal Regulations 50.54 (f) Generic Letter 88-20, Individual Plant Examination for Severe Accident Vulnerabilities, Nov 23, 1988. 

Individual Plant Examination Submittal Guidance, NUREG-1335, August 1989. 

Plant-Specific Individual Plant Examinations (IPEs)... 

The next three subsections describe the role that quantitative risk estimates played in addressing and resolving three important regulatory issues Anticipated Transients Without Scram, Auxiliary Feedwater System Reliability, and Station Blackout. Following these discussions, current policies and practices of the NRC regarding the use of quantitative risk estimates are discussed in subsections addressing the Safety Goal Policy, the Backfit Rule, and Individual Plant Examinations. 

Once a consistent approach for dealing with Safety Goals and Backfits is established, the NRC will have a means to consider backfits and safety issues in a systematic and consistent manner. The process for selecting backfit options will be clarified, and efforts can be focused on those issues most important to risk. While risk will not become the sole measure of the importance of an issue, it can be used to assure that issues are placed in their proper perspective. If a risk-based approach to backfitting is to be implemented, risk analyses must be available to the decision-makers, and the validity of those analyses clearly understood. In some cases, NRC-sponsored risk assessments and special studies can provide the needed information however, another source of information is becoming available. That information source is the Individual Plant Examinations (IPEs). 

NUREG-1407, "Procedural and Submittal Guidance for the Individual Plant Examination of External Events (IPEEE) for Severe Accident Vulnerabilities", June 1992. 

As a separate issue, we made an attempt to look at the possibility that floor-mounted equipment in the drywell, especially across from the pedestal door, could present any significant obstacles with a significant impact on the melt spreading process. We could learn that this was not the case, but we did not manage to examine the relevant constmction details (or any containment) dirwtly for this purpose. Qearly, this is a subject well-suited to the individual plant examinations, and the guidance mentioned above specifically provides for it. 

The ROAAM process applied to the Maik-I liner attack problem is now essential complete. What remains is to conduct e final pe review and issue the final report. The results confirm the NUREG/CR-5423 conclusion that such failure, in file presence of water in the drywell, is physically unreasonable. This conclusion applies to Peach Bottom, but an initial examination of relevant plant parameters indicates that it may also be applicable to all but two plants. The individual plant examination program has been supplied the relevant guidance, and final conclusions on the other plants must await this detailed plwt-spedfic examination. 

U. S. Nuclear Regulatory Commission, Individual Plant Examination Submittal Guidance, USNRC Report, NUREG-1335, August 1989. 

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