ML20216D833
| ML20216D833 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 07/26/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20216D819 | List: |
| References | |
| GL-88-20, NUDOCS 9907300160 | |
| Download: ML20216D833 (7) | |
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STAFF EVALUATION REPORT OF PUBLIC SERVICE ELECTRIC & GAS COMPANY INDIYlDUAL PLANT EXAMINATION OF EXTERNAL EVENTS (IPEEE) SUBMITTAL FOR HOPE CREEK GENERATING STATION
1.0 INTRODUCTION
On June 28,1991, the U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 88-20, Supplement 4 (with NUREG-1407, Procedural and Submittal Guidance) requesting all licensees to perform individual plant examinations of external events (IPEEE) to identify plant-specific vulnerabihties to severe accidents and to report the results to the Commission together with any licensee-determined improvements and corrective actions. In a letter dated July 31, i 1997, the licensee, Public Service Electric and Gas Company (PSE&G), submitted the l response to tivis GL for Hope Creek Generating Station (HCGS). l The NRC contracted with Brookhaven National Laboratory and Sandia National Laboratories to conduct screening reviews in the seismic and fire areas, respectively, of the licensee's IPEEE l
submittal. The staff conducted a screening review of the high winds, floods, and other external events (HFO) area of the submittal. Based on the results of the screening reviews, a request for additional information (RAl) in the seismic area was sent to the licensee on July 23,1998.
The licensee responded to the RAI in a letter dated September 21,1998. Based on the results of the original review, and the additional information provided in the response to the RAl, the staff concluded that the aspects of seismic; fires; and high winds, floods, transportation and other external events were adequate!y addressed. The review findings are summarized in the evaluation section below. Details of the staff's and contractors' review findings are presented in the three technical evaluation reports attached to this staff evaluation report (SER).
In accordance with Supplement 4 to GL 88-20, the licensee provided information to address the resolution of Unresolved Safety issue (USI) A-45, " Shutdown Decay Heat Removal Requirements," Generic Safety issue (GSI)-103, " Design for Probable Maximum Precipitation (PMP)," GSI-57," Effects of Fire Protection System Actuation on Safety-Related Equipment,"
and the Sandia Fire Risk Scoping Study (FRSS) issues. These issues were explicitly requested in Supplement 4 to GL 88-20 and its associated guidance in NUREG-1407. The review findings regarding these issues are included in this SER. The licensee did not propose to resolve any additional USIs or GSis as part of the HCGS IPEEE.
2.0 EVALUATION l
HCGS utilizes a General Electric BWR/4 boiling water reactor with a thermal power output of 3411 MWt. HCGS was designed in the early 1970's and began commercial operation in December 1986. The plant shares a 700-acre site with the Salem Generating Station on the east bank of the Delaware River in Salem County, New Jersey.
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2 The licensee used a PRA to perform their seismic assessment, and the approach was generally consistent with the methodology of NUREG-1407. The risk quantification was done for both .
Electric Power Research Institute (EPRI) and the revised Lawrence Livermore National Laboratory (LLNL) hazard curves. In addition, based on the seismic walkdown results, about 90 components were selected for detailed fragility evaluation. For fire events, the licensee utilized the EPRI Fire Induced Vulnerability Evaluation (FIVE) methodology, 'Nhich was approved by the NRC, to do the initial screening. The licensee per.'ormed a PRA quantification for a detailed analysis of the unscreened fire areas. The licensea evaluated high winds, floods, and other extemal events using the progressive screening approach discussed in NUREG-1407 and GL 88-20, Supplement 4. HCGS was designed to be in compliance with the 1975 standard review plan (SRP) criteria, and the licensee stated that all aspects of its licensing basis as documented in the HCGS Updated Final Safety Analysis Report that are of importance to the IPEEE (e.g.,
tomado wind loads, nearby facility and transportation characteristics) conform to the 1975 SRP criteria. Plant walkdowns were also performed to confirm that there were no significant changes in the plant design or operation that occurred since the plant's licensing.
Core Damaoe Freouency Estimates The licensee estimated the contribution to plant core damage frequency (CDF) from seismic events to be about 1E-6/ reactor year (RY) using the EPRI hazard curve and about 4E-6/RY using the revised LLNL curve. A quantification for fire events, that utilized the EPRI FIVE methodology, indicated that the contribution to plant CDF from fire was about 8E 5/RY. The contribution to CDF from HFO events was estimated by the licensee to be less than the NUREG-1407 screening criteria (i.e.,1E-6/RY). The licensee estimated that the overall CDF due to intemal events was about SE-5/RY including intemal flooding.
Dominant Contributors The licensee determined the dominant contributors to CDF resulting from seismic events (95 percent of the total estimated seismic contribution) were: a seismic failure of all four divisions of a particular set of 120 volt AC instrumentation distribution panels; a seismically induced loss of power to these same panels; a seismic loss of off-site power; a seismic failure of high pressure injection, with subsequent random f ailures including failures of reactor depressurization and of a diesel generator; and a seismic failure of all four divisions of a second set of 120 volt AC l instrumentation distribution panels coupled with a failure of manual recovery of automatic l functions. The dominant contributors to fire CDF (86 percent of the total estimated fire
! contribution) were fires in the building that contains the reactor control area and the diesel
! generators, in this building, particulariy in the cable spreading room, there is a confluence of equipment and cables for different electrical divisions that contributes to the relatively high contribution to fire CDF. Table 4-8 of the licensee's submittal gives a detailed listing by room of the contributors to fire CDF. The CDF contribution due to HFO events was estimated to be below the NUREG-1407 screening criterion (i.e.,1E-6/RY).
The licensee's IPEEE assessment appears to have examined the significant initiating events and dominant accident sequences.
3-Containment Performance The licensee has assessed containment performance under seismic conditions at HCGS by investigating containment structuralintegrity during seismic events, the ruggedness of containment isolation equipment to protect against containment bypass, and isolation and penetration failures (including hatches). The failure of the instrumentation distribution panels that were noted as being the highest contributors to seismic CDF contribution also contribute to a loss of isolation signals to the primary containment isolation valves. The frequency of such an event is estimated by the licensee to be on the order of 1?-7/RY. The licensee evaluated the
, impact of fires on containment performance and found them to be of little significance, similar to the IPE evaluation, with no unique accident sequences as a result of fire.
The licensee's containment performance analyses for seismic and intemal fire events appeared to have considered important containment performance issues and are consistent with the intent of Supplement 4 to GL 88-20.
Generic Safety issues As a part of the IPEEE, a set of generic and unresolved safety issues (USl A-45, GSI-131, GSt-103, GSI-57, and the Sandia FRSS issues) were identified in Supplement 4 to GL 88-20 and its associated guidance in NUREG-1407 as needing to be addressed in the IPEEE. The staff's evaluation of these issues is provided below.
- 1. USl A-45," Shutdown Decay Heat Removal Requirements" This issue was addressed in Section 3.2.1 of the HCGS IPEEE submittal for seismic conditions and in Section 4.9 for fire. No vulnerabilities to the decay heat removal system were found due to either seismic or fire events from the licensee's IPEEE walkdowns and assessments. The staff finds that the licensee's evaluation of USl A-45 is consistent with the guidance provided in Section 6.3.3.1 of NUREG-1407 and, therefore, the staff considers this issue resolved.
- 2. GSI-131,
- Potential Seismic Interaction involving the Movable In-Core Flux Mapping System Used in Westinghouse Plants" This issue does not apply to HCGS.
- 3. GSI-103,
- Design for Probable Maximum Precipitation (PMP)"
The licensee evaluated this issue and reported in Section 5.5.1 of its submittal that the original design for HCGS was consistent with the high intensity rainfall (i.e., PMP) specified in NRC GL 89-22. The staff finds that the licensee's GSI-103 evaluation is consistent with the guidance provided in Section 6.2.2.3 of NUREG-1407 and, therefore, the staff considers this issue resolved.
- 4. GSI-57," Effects of Fire Protection System Actuation on Safety-Related Equipment" l The licensee has asses 0ed the impact of inadvertent actuation of fire protection systems on safety systems which o also one of the issues identified in the FRSS. The submittal addresses this issue in Sect;on 4.10. The staff finds that the licensee's GSI-57 evaluation is consistent with the guidance provided in EPRl's FIVE methodology which I was accepted by the NRC staff and, therefore, the staff considers this issue resolved. )
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- 5. Fire Risk Scoping Study Issues l In Section 4.8 of its submittal, the licensee has explicitly addressed the FRSS issues l following the EPRI guidance on these issues. The licensee states in its submittal that it I has not identified any unacceptable risks or outliers at HCGS due to the FRSS issues.
The staff finds that the licensee's evaluation is consistent with the guidance provided in NUREG-1407 and, therefore, the staff considers these issues resolved.
In addition to those safety issues discussed above that were explicitly requested in Supplement 4 to GL 88-20, four generic safety issues were not specifically identified as issues to be resolved under the IPEEE program; thus, they were not explicitly discussed in Supplement 4 to GL 88-20 or NUREG-1407. However, subsequent to the issuance of the GL, the NRC evaluated the scope and the specific information requested in the GL and the associated IPEEE guidance, and concluded that the plant-specific analyses being requested in the IPEEE program could also be used, through a satisf actory IPEEE submittal review, to resolve the extemal event aspects of these four safety issues. The following discussions summarize the staff's evaluation of these safety issues at HCGS.
- 1. GSI-147,
- Fire-Induced Altemate Shutdown / Control Room Panelinteractions" The licensee's IPEEE submittal contains a discussion addressing this issue in Section 4.8.5 on Fire Risk Scoping Study issues. In the discussion, the licensee states that HCGS has a safe shutdown f acility, the remote shutdown system (RSS), that is independent of the control room. The RSS is comprised of a remote shutdown panel (RSP) and redundant shutdown instrumentation and controls. The licensee states that once control has been transferred to the RSP from the main control room, the RSP is independent of the main control room and fully capable of performing a safe reactor shutdown to a hot - and ultimately to a cold condition. Based on the results of the IPEEE submittal review, the staff considers that the licensee's process is capable of identifying potential vulnerabilities associated with this issue. On the basis that no vulnerability associated with this issue was identified in the IPEEE submittal, the staff considers this issue resolved.
- 2. GSI-148, " Smoke Control and Manual Fire-Fighting Effectiveness" i
The licensee's IPEEE submittal contains information addressing this issue in Section 4.8.4.1. The licensee addressed this issue and concluded that the HCGS fire protection systems and procedures provide adequate assurance that manual fire fighting effectiveness will not be significantly degraded from smoke and other fire effects.
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Based on the results of the IPEEE submittal review, the staff considers that the licensee's process is capable of identifying potential vulnerabilities associated with this issue. On the basis that no vulnerability associated with this issue was identified in the IPEEE submittal, the staff considers this issue resolved for HCGS.
- 3. GSI-156. " Systematic Evaluation Program (SEP)"
- 4. GSI-172,
- Multiple System Responses Program (MSRP)"
The licensee's IPEEE submittal contains information directly addressing the following external-event-related MSRP issues: (1) effects of fire protection system actuation on safety-related and non safety-related equipment (Section 4.8.1.2); (2) seismically induced fire suppression system actuation (Section 4.8.1.2); (3) seismically induced fires j (Section 4.8.1.1); (4) effects of hydrogen line rupture (Section 4.8.1.1); (5) the IPEEE-
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related aspects of common cause failures associated with human errors (Section i 3.1.5.3.2) for seismic events and (Sections 4.6.5 and 4.8.4.3) for fires; (6) non safety- I related control system / safety-related system dependencies (Sections 3.2.3 and 4.8.5);
l (7) effects of flooding and/or moisture intrusion on non safety-related and safety-related equipment (Section 4.8.10); (8) seismically induced spatial / functional interactions .
(Sections 3.1.2.2 and 3.2.3); (9) seismically induced flooding (Section 3.1.2.2.1); (10) seismically induced relay chatter (Section 3.1.5.4); and (11) evaluation of earthquake magnitude greater than safe shutdown earthquake (Section 3).
Based on the results of the IPEEE submittal review, the staff considers that the licensee's process is capable of identifying potential vulnerabilities associated with GSI-172. On the basis that no potential vulnerability associated with this issue was identified in the IPEEE submittal, the staff considers the IPEEE-related aspects of this issue to be resolved for HCGS.
Uniaue Plant Features. Potential Vulnerabilities. and improvements 1
In Section 7 of its submittal the licensee discussed the HCGS safety features and plant l improvements. The submittal did not identify any unique safety features at the plant.
The licensee defined a vulnerability as a scenario that contributed inordinately to the HCGS CDF, as compared to other plants of similar type and vintage. The licensee stated that no fundamental weaknesses or vulnerabilities with regard to external events were identified during their evaluation. Section 7 of the submittal did, however, discuss two improvements that have been implemented as a result of the IPEEE review. The first improvement was a physical improvement, the addition of a missile shield in front of the door to the Technical Support Center to protect safety-related cables inside the building from tornado missiles. The second improvement involved working with the U.S. Coast Guard to bring about the discontinuation of shipments of explosives along the Delaware River in the vicinity of the Hope Creek and Salem Nuclear Generating Stations. These shipments, that were discovered during the licensee's IPEEE review of potential transportation-related hazards, occurred during the summer of 1996
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l and had not been appropriately authorized by the U.S. Coast Guard.
3.0 CONQLUSIONS On the basis of the overall review findings, the staff concludes that: (1) the licensee's IPEEE is complete with regard to the information requested by Supplement 4 to GL 88-20 (and associated guidance in NUREG 1407), and (2) the IPEEE results are reasonable given the HCGS design, operation, and history. Therefore, the staff concludes that the licensee's IPEEE process is capable of identifying the most likely severe accidents and severe accident' velnerabilities, and therefore, that the HCGS IPEEE has met the intent of Supplement 4 to GL 88 20 and the resolution of specific generic safety issues discussed in this SER.
It should be noted th6t the staff focused its review primarily on the licensee's ability to examine HCGS for severe accident vulnerabilities. Although certain aspects of the IPEEE were explored in more detail than others, the review was not intended to validate the accuracy of the licensee's detailed findings (or quantification estimates) that underlie or stemmed from the examination. Therefore, this SER does not constitute NRC approval or endorsement of any IPEEE material for purposes other than those associated with meeting the intent of Supplement l 4 to GL 88-20 and the resolution of specific generic safety issues discussed in this SER.
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Attachments: 1. Technical Evaluation Report - Seismic Events {
- 2. Technical Evaluation Report - Files i
- 3. Technical Evaluation Report - High Winds, Floods and other Extemal Events I l
Principal Contributors: B. Hardin A. Rubin Date:
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Attachment 1 HOPE CREEK GENERATING STATION INDIVIDUAL PLANT EXAMINATION OF EXTERNAL EVENTS (IPEEE)
TECHNICAL EVALUATION REPORT SEISMIC EVENTS
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