ML20134L765
| ML20134L765 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 11/12/1996 |
| From: | Rinaldi F NRC (Affiliation Not Assigned) |
| To: | Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| References | |
| GL-88-20, TAC-M83636, TAC-M83637, NUDOCS 9611210207 | |
| Download: ML20134L765 (4) | |
Text
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UNITED STATES
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WASHINGTON, D.C. 2000H001
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November 12, 1996 Mr. George A. Hunger, Jr.
Director-Licensing, MC 62A-1 PECO Energy company Correspondence Control Desk P.O. Box No. 195 Wayne, PA 19087-0195 l
SUBJECT:
RESPONSE TO OUR REQUEST FOR ADDITIONAL INFORMATION REGARDING REVIEW OF INDIVIDUAL PLANT EXAMINATION OF EXTERNAL EVENTS (IPEEE) 1 FOR LIMERICK GENERATING STATION, UNITS 1 AND 2 (TAC NOS. M83636 AND M83637)
REFERENCES:
1.
Letter from F. Rinaldi, U.S. NRC, to G. A. Hunger, PECO i
Energy Company, dated December 22, 1995.
2.
Letter from G. A. Hunger, Jr., PECO Energy Company, to U.S. NRC, dated June 28, 1996.
1 3.
Letter from G. A. Hunger, Jr., PECO Energy Company, to U.S. NRC, dated July 28, 1995.
i 4.
Letter from G. A. Hunger, Jr., PECO Energy Company, to U.S. NRC, dated June 26, 1995.
5.
U.S. NRC Generic Letter 88-20, Supplement 5, " Individual Plant Examination of External Events for Severe Accident Vulnerabilities," September 8, 1995.
Dear Mr. Hunger:
I i
In your response (Reference 2) to a request for additional information (RAI) l (Reference 1) regarding seismic question 1, you did.not provide all the requested information. You stated in Reference 2.th'at in light of the revised Lawrence Livermore National Laboratory's (LLNL) seismic hazard curves, you believe that a reduced-scope evaluation for Limerick and Peach Bottom nuclear power plants, as previously stated in Reference 3, would meet the intent of Supplement 4 to GL 88-20.
You stated further in Reference 2 that you are awaiting NRC's response to Refere'nce 3 citing a statement in Supplement 5 to 4
GL 88-20:
" Licensees who prepiously submitted their requests to modify their seismic IPEEEs may choose n't to submit any response to this generic letter o
l supplement; should that be the case, NRC will respond separately to their previous requests."
We understand that you are still awaiting NRC's response to your July 28, 1995, letter (Reference 3). As you are m e, the Limerick IPEEE was h
submitted on June 26,1995 (Reference 4); and Supplement 5 to GL 88-20 V
(Reference 5) was not issued until September 1995.
In September 1995 during the Limerick IPEEE submittal review, the staff noted that a reduced-scope, instead of a focused-scope, seismic margins approach was used for Limerick h
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9611210207 961112 PDR ADOCK 0500 2
G. Hunger seismic IPEEE. The staff decided at that time, instead of rejecting the IPEEE submittal and requesting the resubmittal of a completed IPEEE information package, to issue a specific request for the missing information (seismic question 1 cf Reference 1). This situation was discussed with your staff in a conference call held on January 18, 1996.
Participants of this conference call included J. Phillabaum (PECO), J. Basilio (PECO), A. Marie (PEC3),
F. Rinaldi (NRC), and J. Chen (NRC).
With regard to the reasons stated in Reference 3 to justify the use of a i
reduced-scope seismic approach for Limerick and Peach Bottom, we would like to offer the following comments, and refer you to Supplement 5 to GL 88-20.
1.
"The 1993 LLNL results demonstrate that the seismic hazard is much less than what the NRC staff originally believed."
It is true that the 1993 LLNL seismic hazard estimates are lower than the 1989 LLNL seismic hazard estimates; however, they are generally higher than the 1989 Electric Power Research Institute's (EPRI's) seismic hazard estimates. As you may be aware that the staff did perform a specific seismic revisit study to determine whether the 1993 LLNL estimates would significantly change the original binning results, and the study indicated that the binning would not be significantly affected.
(The process used to define the binning in NUREG-1408 employed comparisons of the relative i
seismic severity, not the absolute seismic hazard probabilities, of the Eastern U.S. plant sites.
Both 1989 LLNL and EPRI estimates were used in the original process.) Supplement 5 to GL 88-20 was issued to report the results of the revisit study and document the NRC's position that the binning would not be changed.
2.
"The probability of exceeding the safe shutdown earthquake (SSE) using the revised 1993 LLNL mean hazard results is less than the mean probability of exceeding the SSE at the reduced scope plants identified in NUREG-1407."
As discussed above, the absolute seismic hazard probabilities were not used in the binning process for NUREG-1407. Therefore, your second reason does not justify that Limerick or Peach Bottom should be considered as a reduced-scope plant.
3.
"The probability of exceeding the SSE based Jpon 1993 LLNL mean hazard results is less than the probability of exceeding the 0.3g NUREG/CR-0098, ' Development of Criteria for Seismic Review of Selected Nuclear Power Plants,' review level spectrum based on the 1993 LLNL mean hazard results."
It seems that this statement should be applicable for all Eastern U.S. sites. However, the NRC staff feels that it cannot be used to justify that any plant should be re-assigned to the reduced-scope bin.
G. Hunger '
In Supplement 5, we did not change the binning assignment but made some adjustments in overall scope. The basis for the staff's action, including discussion of issues contained in your July 28, 1995, letter, is also discussed in the supplement.
Therefore, we have concluded that ycur decision to change the scope for the seismic events portion of the IPEEE is not justified or consistent with the staff position in Supplement 5.
As you are aware, our IPEEE submittal review will focus on the information requested in Supplement 4 and Supplement 5, as appropriate, to GL 88-20. The staff will attempt to obtain any missing information in the IPEEE submittal through an RAI.
If this attempt fails to 4
get meaningful information, we will conclude that the submitted IPEEE did not meet the intent of the GL 88-20 supplement.
Sincerely,
/S/
Frank Rinaldi, Project Manager Project Directorate I-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation cc:
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G. Hunger l l
In Supplement 5, we did not change the binning assignment but made some adjustments in overall scope. The basis for the staff's action, including discussion of issues contained in your July 28, 1995, letter, is also
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discussed in the supplement.
Therefore, we have concluded that your decision to change the scope for the seismic events portion of the IPEEE is not justified or consistent with the staff position in Supplement 5.
As you are aware, our IPEEE submittal review will focus on the information requested in Supplement 4 and Supplement 5, as appropriate, to GL 88-20. The staff will attempt to obtain any missing information in the IPEEE submittal through an RAI.
If this attempt fails to get meaningful information, we will conclude that the submitted IPEEE did not meet the intent of the GL 88-20 supplement.
Sincerely, lnh-t-~ G. / A r Frank Rinaldi, Project Manager Project Directorate I-2 Division of Reactor Projects - I/II j
Office of Nuclear Reactor Regulation Doci;et Nos. 50-352/353 cc:
See next page
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