ML17164A741
| ML17164A741 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 08/11/1998 |
| From: | Nerses V NRC (Affiliation Not Assigned) |
| To: | Byram R PENNSYLVANIA POWER & LIGHT CO. |
| Shared Package | |
| ML17164A742 | List: |
| References | |
| GL-88-20, TAC-M74478, TAC-M74479, NUDOCS 9808180274 | |
| Download: ML17164A741 (8) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 August 11, 1998 go-3II7 Mr. Robert G. Byram Senior Vice President-Generation and Chief Nuclear Officer Pennsylvania Power'and Light Company 2 North Ninth Street Allentown, PA 18101
SUBJECT:
REVIEW OF THE SUSQUEHANNA STEAM ELECTRIC STATION, UNITS 1 AND 2, INDIVIDUALPLANT EXAMINATIONSUBMITTAL-INTERNALEVENTS (TAC NOS. M74478 AND M74479)
Dear Mr. Byram:
Enclosed is the NRC staffs supplement to the October 27, 1997, staff evaluation report (SER) of the Susquehanna Steam Electric Station (SSES), Units 1 and 2, Individual Plant Examination (IPE) submittal for internal events, including internal flooding.
On October 27, 1997, the NRC forwarded to Pennsylvania Power 8 Light Company (PPSL) an SER stating that the NRC staff could not conclude that the SSES IPE submittal met the intent of Generic Letter (GL) 88-20.
In response, you submitted additional information and on February 27, 1998, briefed the staff on revisions made to address the issues identified in the SER.
On April 1, 1998, the staff audited the SSES IPE at your offices in Allentown, Pennsylvania.
The enclosed SER supplement addresses the final resolution of the issues raised by the staff in its original SER.
In the revised IPE, the calculated mean core damage frequency (CDF) is about 7E-7/reactor-cycle of 15 months (or about 5E-7/reactor-year), which is about a factor of seven higher than the original IPE CDF of 1E-7/reactor-cycle.
Anticipated transient without scram contributes about 63% to the CDF, loss of decay heat removal contributes about 23%, internal flooding contributes about 10%, station blackout contributes about 2%, and transients contribute about 2%. The contribution of loss-of-coolant-accident (LOCA) and interfacing systems LOCA is less than 1%.
You have implemented all of the plant improvements identified in the original IPE, as well as additional improvements.
On the basis of the information provided, the staff concludes that the revised SSES IPE process is adequate to meet the following four objectives of GL 88-20:
t To develop an appreciation for severe accident behavior, To understand the most likely severe accident sequences that could occur at the plant, To gain a more quantitative understanding of the overall probabilities of core damage and fission product releases, and (4)
Ifnecessary, to reduce the overall probabilities of core damage and fission product releases by modifying, where appropriate, hardware and procedures that would help prevent or'mitigate severe accidents.
9808i80274 9808%i PDR ADOCK 05000387 P
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Robert G. Byram Therefore, the staff concludes that the SSES IPE submittal, as supplemented, meets the intent of GL 88-20. The staff notes your commitment to identify instances of plant improvements in order to maintain a low CDF or further decrease the CDF, at SSES.
The staff also notes PP8L's strong in-house PRA capability. The SSES IPE was performed almost entirely in-house; also, according to PP8L, it is continually using and updating the SSES PRA. Although the NRC staff had several concerns about the original SSES IPE approach, because of the revisions performed in the front-end portion, the ongoing use of the PRA in conjunction with PP&L's defense-in-depth approach, and the ongoing identification and implementation of improvements, the staff believes that the current front-end analysis of the SSES IPE presents an exemplary analysis.
The staff encourages you to continually confirm the IPE's reliability of equipment and operator performance ensuring that it portrays SSES plant capability under severe accident conditions.
However, some weaknesses still remain in the IPE's back-end analysis.
The staff believes that it is unlikely that these remaining weaknesses have affected the overall conclusion from the revised analysis or the capability of identifying vulnerabilities; it may, however, limit its usefulness in other regulatory applications, especially in applications related to containment performance.
The staff believes that PP8L can enhance the usefulness of the SSES IPE by addressing the weaknesses discussed in the enclosed SER supplement.
It should be noted, that the staff focused its review primarily on your ability to examine SSES Units 1 and 2 for severe accident vuinerabilities. Although certain aspects of the IPE were explored in more detail than others, the review is not intended to validate the accuracy of the detailed findings (or quantification estimates) that stemmed from the examination.
Therefore, this SER does not constitute NRC approval or endorsement of any IPE material for purposes other than those associated with meeting the intent of GL 88-20.
Ifyou have any questions regarding the enclosed SER supplement, please contact me at (301) 415-1484.
Sincerely,
/S/
Docket Nos. 50-387/50-388
Enclosure:
As stated Victor Nerses, Senior Project Manager Project Directorate I-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation RCapra MO'Brien OGC ACRS cc w/encl: See next page EOISUJlM:
Docket File PUBLIC PDI-2 Reading JZwolinski CAnderson, RGN I VNerses THarris (E-Mail SE)
ELois JLane OFFICE PDI-2/PM PDI-2/D NAME V erses:mw
/f /~v O'rien RCa ra ~
DATE g / 5 /98
%ass 8 /ll /98 OFFICIALRECORD COPY DOCUMENT NAME: a:>SUM74478.LTR
Robert G. Byram Therefore, the staff concludes that the SSES IPE submittal, as supplemented, meets the intent of GL 88-20. The staff notes. your commitment to identify instances of plant improvements in order to maintain a low CDF or further decrease the CDF, at SSES.
The staff also notes PP8L's strong in-house PRA capability. The SSES IPE was performed almost entirely in-house; also, according to PP8L, it is continually using and updating the SSES PRA. Although the NRC staff had several concerns about the original SSES IPE approach, because of the revisions performed in the front-end portion, the ongoing use of the PRA in conjunction with PP8L's defense-in-depth approach, and the ongoing identification and implementation of improvements, the staff believes that.the current front-end analysis of the SSES IPE presents an exemplary analysis.
The staff encourages you to continually confirm the IPE's reliabilityof equipment and operator performance ensuring that it portrays SSES plant capability under severe accident conditions.
However, some weaknesses still remain in the IPE's back-end analysis.
The staff believes that it is unlikely that these remaining weaknesses have affected the overall conclusion from the revised analysis or the capability of identifying vulnerabilities; it may, however, limitits usefulness in other regulatory applications, especially in applications related to containment performance.
The staff believes that PPBL can enhance the usefulness of the SSES IPE by addressing the weaknesses discussed in the enclosed SER supplement.
It should be noted, that the staff focused its review primarily on your ability to examine SSES Units 1 and 2 for severe. accident vulnerabilities. Although certain aspects of the IPE were explored in more detail than others, the review is not intended to validate the accuracy of the detailed findings (or quantification estimates) that stemmed from the examination.
Therefore, this SER does not constitute NRC approval or endorsement of any IPE material for purposes other than those associated with meeting the intent of GL 88-20.
Ifyou have any questions regarding the enclosed SER supplement, please contact me at (301) 415-1484.
Sincerely, Docket Nos. 50-387/50-388
Enclosure:
As stated cc w/encl: See next page Victor Nerses, Senior Project Manager Project Directorate I-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Mr. Robert G. Byram Pennsylvania Power & Light Company Susquehanna Steam Electric Station, Units1 &2 CC:
Jay Silberg, Esq.
Shaw, Pittman, Potts &Trowbridge 2300 N Street N.W.
Washington, D.C. 20037 Bryan A. Snapp, Esq.
Assistant Corporate Counsel Pennsylvania Power & Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Licensing Group Supervisor Pennsylvania Power & Light Company 2 North Ninth Street Allentown, Pennsylvania I8I01 Senior Resident Inspector U. S. Nuclear Regulatory Commission P.O. Box 35 Berwick, Pennsylvania 18603-0035 Director-Bureau of Radiation Protection Pennsylvania Department of Environmental Resources P. O. Box 8469 Harrisburg, Pennsylvania 17105-8469 Mr. Jesse C. Tilton, III Allegheny Elec. Cooperative, Inc.
212 Locust Street P.O. Box 1266 Harrisburg, Pennsylvania 17108-1266 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, Pennsylvania 19406 General Manager Susquehanna'Steam Electric Station Pennsylvania Power and LIght Company Box 467 Berwick, Pennsylvania 18603 Mr. Herbert D, Woodeshick Special Office of the President Pennsylvania Power and Light Company Rural Route 1, Box 1797 Berwick, Pennsylvania 18603 George T. Jones Vice President-Nuclear Operations Pennsylvania Power and Light Company 2 North Ninth Street Allentown, Pennsylvania 18101 Dr. Judith Johnsrud National Energy Committee Sierra Club 433 Orlando Avenue State College; PA 16803 Chairman Board of Supervisors 738 East Third Street Berwick, PA 18603
Robert G. Byram i.
"r, Therefore, the staff concludes that the SSES IPE submittal, as supplemented, meets the intent,"
of GL 88-20. The staff notes your commitment to identify instances of plant improvements in order to maintain a low CDF or further decrease the CDF, at SSES.
The staff also notes PP8L's strong in-house PRA capability. The SSES IPE was performed almost entirely in-house; also, according to PP8L, it is continually using and updating the SSES PRA. Although the NRC staff had several concerns about the original SSES IPE approach, because of the revisions performed in the front-end portion, the ongoing use of the PRA in conjunction with PP&L's defense-in-depth approach, and the ongoing identification and implementation of improvements, the staff believes that the current front-end analysis of the SSES IPE presents an exemplary analysis.
The staff encourages you to continually confirm the IPE's reliabilityof equipment and operator performance ensuring that it portrays SSES plant capability under severe accident conditions.
However, some weaknesses still remain in the IPE's back-end analysis.
The staff believes that it is unlikely that these remaining weaknesses have affected the overall conclusion from the revised analysis or the capability of identifying vulnerabilities; it may, however, limit its usefulness in other regulatory applications, especially in applications related to containment performance.
The staff believes that PP8L can enhance the usefulness of the SSES IPE by addressing the weaknesses discussed in the enclosed SER supplement.
It should be noted, that the staff focused its review primarily on your ability to examine SSES Units 1 and 2 for severe accident vulnerabilities. Although certain aspects of the IPE were explored in more detail than others, the review is not intended to validate the accuracy of the detailed findings (or quantification estimates) that stemmed from the examination.
Therefore, this SER does not constitute NRC approval or endorsement of any IPE material for purposes other than those associated with meeting the intent of GL 88-20.
Ifyou have any questions regarding the enclosed SER supplement, please contact me at (301) 415-1484.
Sincerely,
/s/
Docket Nos. 50-387/50-388 Victor Nerses, Senior Project Manager Project Directorate l Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Enclosure:
As stated cc w/encl: See next page
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Docket File PUBLIC PDI-2 Reading JZwolinski RCapra MO'Brien OGC ACRS CAnderson, RGN I VNerses THarris (E-Mail SE)
ELois JLane OFFICE PDI-2/PM NAME VNerses:mw DATE I/5 /98
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'8 /It /98 OFFICIALRECORD COPY DOCUMENT NAME: a:>SUM74478.LTR
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