ML20198E109

Safety Evaluation Accepting Licensee 920921 120-day Response to GL 87-02, Verification of Seismic Adequacy of Mechanical & Electrical Equipment in Operating Reactors,Usi A-46

ML20198E109
Person / Time
Site:	Cooper
Issue date:	11/25/1992
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20198E101	List: ML20198E095 ML20198E109
References
REF-GTECI-A-46, REF-GTECI-SC, TASK-A-46, TASK-OR GL-87-02, GL-87-2, TAC-M69439, NUDOCS 9212040129
Download: ML20198E109 (4)

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Enclosure 1

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UNITED STATES l' - 'n NUCLEAR REGULATORY COMMISSION t, -y WASHINGTON. D. C. 20555 j

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION EVALUATION OF NEBRASKA PUBLIC POWER DISTRICT'S 110-DAY RESPONSE TO SUPPLEMENT NO. 1 TO GENERIC LETTER 8J-32 FOR COOPER NUCLEAR STATION DOCKET NO. 50-E93 TAC NO. M69439 INTRODUCTION On May 22, 1992, the NRC staff issued Supplement No. I to Generic Letter (GL) 87-02, " Verification of Seismic Adequacy of Mechanical and Electrical Equipment in Operating Rcettors, Unresolved Safety Issue (JSI) A-46." In this supplement, the staff requested that licensees submit the following information within 120 days of the issue date of the supplement:

I. A statement whether you cor.ait to use both the Seismic Qualification Utility Group (SQUG) commitments and the implementation guidance provided in the Generic Implementation Procedure, Revision 2 (GIP-2) as supplemented by the staff's Supplemental Safety Evaluation Report No. 2 (SSER-2) for the resolution of USI A-46. In this case, any deviation from GIP-2, as supplemented by the SSER-2, must be identified, justified, and documented. If you do not make such a commitment, you must provide youi alternative for responding to GL 87-02.

2. A plant-specific schedule for the implementation of the GIP-2 and submission of a report to the staff that summarizes the results of the USI A-46 review, if you are committing to implement GIP-2. This schedule shall be such that each affected plant will complete its implementetion and submit the summary report within 3 years after the issuance of SSER-2, unless otherwise justified.

3. The detailed information as to what procedures and criteria were used to generate the in-structure response spectra to be used for USI A-46 as requested in SSER-2. The licensee's in-structure response spectra are considered acceptable for USI A-46 unless the staff indicates otherwise during a 60-day review period.

In addition, the staff requested in SSER-2 that each licensee inform the staff, in its 120-day response, if it intends to change its licensing basis to reflect a commitment to the USI A-46 (GIP-2) methodolcgy for verifying the 9212040129 921125 8 DR ADOCK 0500

4 seismic adequacy of mechanical and electrical equipment, prior to receipt of the staff's plant-specific safety evaluation resolving USI A-46.

By letter dated September 21, 1992, the Nebraska Public Power District (the licensee for Cooner Nuclear Station) submitted its response to Supplement No. I to Gener c Letter (GL) 87-02.

i EVALUATION Implementation of SOUG and GIP-2 commitments With regard to Item 1, the licensee stated that it "... commits to the SQUG commitments set forth in the GIP in their entirety, including the clarifications, interpretations, and exceptions identified in the SSER-2 as clarified by the August 21, 1992, SQUG

, letter responding to SSER-2." The licensee also stated that it "... generally will be guided by the remaining (non-commitment) sections of the GIP, i.e.,

GIP implementation guidance, which comprises suggested methods for implementing the applicable comitments."

The licensee's response is unclear as te whether or not the licensee intends to implement both the SQUG commitments and the implementation guidance. In accepting GIP-2 as a method for resolving USI A-46, it was the staff's understanding that the SQUG members who chose to implement GIP-2 would '

essentially use the entire procedure, including the SQUG commitments, which contain the general programmatic objectives and goals, and the implementation guidance, which contains the specific criteria and procedures to be used for the resolution of USI A-46. This understanding was the basis for the staff's position, wt.ich was stated in SSER-2, that if the licensee commits to use GIP-2 for the impicnentation of USI A-46, it must commit to both the SQUG commitments and the use of the entire implementation guidance provided in GIP-2, un'less otherwise justified to the staff. In order to allow some flexibility in implementing GIP-2, the staff acknowledged in the supplement to GL 87-02 that SQUG members wno commit to GIP-2 (both the SQUG commitments and the implementation guidance) may deviate from it provided that such deviations are identified, documented and justified. However, it was also indicated in SSER-2 that if a licensee uses methods that deviate from the criteria and procedures described in the SQUG commitments and in the implementation guidance of GIP-2 without prior NRC approval, the staff may find the use of such methods unacceptable with regard to satisfying the provisions of GL 87-02.

In light of the above, the staff interprets the licensee's response to Supplement No, I to GL 87-02 as a commitment to the entire GIP-2 including both the SQUG commitments and the implementation guidance, and therefore considers it acceptable. If the staff's interpretation is incorrect, then in accordance with Supplement No. 1 to GL 87-02, the licensee should provide for staff review, as soon as practicable prior to implementation, its alternative criteria and proc.dures for responding to GL 87-02.

. In addition, Enclosure 2 provides the staff's response, dated October 2, 1992, to the August 21, 1992, SQUG letter. The staff does not concur with all of the SQUG's clarifications and positions stated in that letter, and thus, the licensee should not use the August 21, 1992, letter as guidance in responding to Supplement No. I to GL 87-02. The licensee should refer to the NRC staff's October 2,1992 letter (see Enclosure 2) for the staff's position on the SQUG letter.

Imolementation schedule With regard to Item 2, the licensco stated that it I will submit a summary report to the NRC summarizing the results of the  ;

USI A-46 program at Cooper Nuclear Station by May 22, 1995. This submittal  !

date is within the 3-year response period requested by the staff and is therefore acceptable.

In-structure response spectra With regard to Item 3, the NRC staff has reviewed the licensee's in-structure response spectra to be used for USI A-46 evaluations. Specifically, the staff has reviewed the licensee's response with the objective of assessing the acceptability of the response to item 11.4.2.3 of SSER-2.

The plant SSE peak ground acceleration (PGA) is 0.209 The licensee has developed 'in-structure response spectra (IRS) utilizing the N69W component of the July 1952 Taft, California, earthquake records normalized to 0.20g PGA.

The 7% damped design response spectrum is the Housner spectral shape with amplifications determined by approximately averaging the peaks and valleys of the Taft spectrum. The licensee states that the IRS should be considered as the " conservative design" spectra for verifying the plant equipment. However, the staff does not agree. The parameters that are not in favor of such acceptance are: non-conservative input spectrum, Regulatory Guide 1.61 type damping, and soil-property variations not according to the Standard Review-Plan. The applicat* ef the design motion at the foundation level and some unspecified broadening of IRS peaks can be considered as conserotive considerations. Overall, a review of the IRS provided by the liensee (if at 1/2% or 1% damping as stated on page 6 of the licensee':, submittal) does not lend itself to such an acceptance.

Based on our review of the licensee response and the staff positions l delineated in the SSER-2, we conclude that the licensee response is adequate i

and acceptable, but the IRS developed by the licensee should be considered as

" median centered" in-structure response spectra, rather than " conservative design" spectra. This conclusion is based on the assumption that the stateme-ts made in the submittal,-including the procedures used in generation of the IRS, correctly reflect the FSAR and other licensing basis. The staff may audit the process by which the in-structure response spectra were j generated.

i It is noted that the licensee did not indicate in its submittal that it

! intended to change its licensing basis to reflect a commitment to the USI A-46 l methodology prior to receipt of the staff's plant-specific SER.

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CONCLUSIONS i The staff interprets the licensee's response to Supplement No. I to GL 87-02 as a commitment to the entire GIP-2, including both the SQUG commitments and i the implementation gridance, and therefore considers it acceptable. If this 1 interpretation is incorrect, and the licensee does not commit to implement the entire GIP-R, then in accordance with Supplement No. I to GL 87-02, the 1

licensee'should provide _ for staff review, as soon as practicable prior to.

{ implementation, its alternative criteria and procedures for responding to

! GL 87-02. Additionally the licensee should not merely follow the August 21,

! 1992, SQUG letter for implementing GIP-2, but should refer to the staff's j October 2,1992 respor.se to the- SQUG letter (see Enclosure 2).

1 The implementation schedule proposed by the licensee is within the 3-year .

{ response period requested by-the staff in Supplement No, I to GL 87-02 and is j therefore acceptable.

i l The in-structure response spectra developed by the licensee is adequate and acceptable, but should be considered as " median centered" in-structure -

response sis;tra, rather than " conservative design" spectra, i- - Principal Contributors

H. Ashar 4

P.'Chen M. McBrearty i_ Date: November 25, 1992 i

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ENCLOSURE 2

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4 Mr. Neil Smith, Chairman Seismic Qualification Utility Group l

c/o EPRI 3 1019 19th Street, N.W.

Washington, DC 20036 )

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SUBJECT:

NRC RESPONSE TO SEISMIC QUALIFICATION UTILITY GROUP (SQUG)

Re: Letter, N. Smith, EPRI, To J. Partlow, NRR, datad August 21, 1992,  !

concerning USI A-46 Issues, j

Dear Mr. Smith:

This is to acknowledge the receipt of the SQUG response to Supplement No. I to Generic Letter (GL) 87-02, and Supplemental Safety Evaluation (SSER) No. 2, on the SQUG Generic Implementation Procedure for Seismic Verification of Nuclear Plant Equipment, Revision 2, as corrected February 14, 1992 (GIP-2). The NRC staff believes thr.t successful implementation of the. entire GIP-2,' supple-mented by the staff's SSER No. 2, by each SQUG licensee will result in cost-4 effective plant safety enhancement for their USI A-46 plants.

The staff also believes that the positions delineated in Supplement No. I to

Gl. 87-02 and SSER No. 2 are clear and correct, and should not be misinterpret-ed. The staff's comments on SQUG's August 21, 1992, letter and attachment are provided in the enclosure to this letter. If you need further clarification concerning our response, please contact Mr. James Norberg at 504-3288.

1 Sincerely, r

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% dit James G. Cartlow

. As'sociate Director for Projects Office of Nuclear Reactor Regulation

Enclosure:

As stated ,

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i ,. * -s ENCLOSURE I

!. NRC's Coments on the SOUG Letter of Auaust 21. 1992

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1. In regard to the issue of seismic qualification, the staff

-reiterates the position stated in the SSER No. 2, in that the GIP-2 methodology is not considered to be a seismic qualification j method, rather, it is an= acceptable evaluation method for US! A-46 plants only, to verify the seismic adequacy of the safe-shutdown equipment and to ensure that the pertinent equipment.

seismic requirements of General Design Criterion 2 and the pur

'of the NRC regulations relevant-to equipment seismic adequacy pose including 10 CFR Part 100 are satisfied.-

( 2. The second paragraph on page 2 of your letter addressed the issue

of timing of staff response to additional information requested i from a licensee. Although you ar~e correct in your. statement l regarding the sixty-day. period for response to initial. submittal

of in-structure response spectra (ISRS) information, we do not

! agree that_the same concept applies to a licensee's submittal of i additional information received following a rejection or a

! question from-the staff. To eliminate any potential misunder-I standing in this regard, the staff has determined that it will respond to any submittal of additional information received from a licensee within 60 days. However, in this response, the staff l will either state.its approvP (or rejection) of the information--

i' provided, or indicate the tt Juration needed for the review-of such information, prior to'h , Amitting a follow-up response of i acceptance-(or rejection) to~the licensee. This time duration i will vary depending on the complexity of the submittal. .

3.

Regarding the EBAC and ANCHOR computer. codes, the_ staff's

[ evaluations and concerns stated in the SSER No.:2 are correct.and i valid. The ANCHOR code does not consider the effects of base t

plate flexibility on the ' anchorage capacity,

4. With respect to transfer of knowledge regarding major problems- '

l identified, and lessons--learned, in the USl A-46 plant walkdowns L and third-party reviews, we request that you include the NRC in l the distribution of written communications to all member utilities in this regard, and infore the NRC staff of any planned workshops on A-46_ implementation for possible staff participation.

_ NRC's Coments on th' e Procedure for Reviewina- the GIP -

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1. _The staff supports SQUG's establishment of a; Peer Review Panel composed of. seismic experts since it should serve to enhance the-

. review process.of substantive changes to-the technical-

! requirements in the GIP,. prior to-its submittal to NRC for approval. However, since the NRC no longer intends to help-t finance a Peer Review Panel, the staff does not believe it=

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is appropriate to participate in the selection of the Peer Review members, who will be financed by SQUG/EPRI. We would like to.

emphasize-that staff's review of a proposed GIP change will j receive thorough independent NRC evaluation and will be assessed '

on its merits.

2. With respect to the NRC review and approval of the changes to the 'I

! GIP (Item 5, page 3 of the procedure), the staff's position on the l 15pte of-its response timing is identical.to that delineated in i the response to a licensee submittal of additional information (refer to item 2 of NRC's Comments on the SQUG letter in this

! enclosure). This comment also applies to the section " LICENSING l l CONSIDERATIONS" on page 5 of the Attachment to-the SQUG letter, f

3. With respect to item 4, " Additional Restrictions," the text should

. be expanded to reflect that new information which indicates that existing GIP criteria and guidelines may be unconservative should

be evaluated for potential 10 CFR Part 21 implications.

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