ML18153D181
| ML18153D181 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 11/20/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18153D180 | List: |
| References | |
| REF-GTECI-A-46, REF-GTECI-SC, TASK-A-46, TASK-OR GL-87-02, GL-87-2, NUDOCS 9211300400 | |
| Download: ML18153D181 (8) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555
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sA F ETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION EVALUATION OF VIRGINIA ELECTRIC AND POWER COMPANY'S NORTH ANNA POWER STATION, UNITS 1 AND 2 AND SURRY POWER STATION, UNITS 1 AND 2 120-DAY RESPONSE TO SUPPLEMENT NO. I TO GENERIC LETTER 87-02 DOCKET NOS. 50-338/339, 50-280/281 INTRODUCTION By letter dated September 18, 1992, the Virginia Electric and Power Company, the licensee, submitted its response to Supplement No. I to Generic Letter (GL) 87-02, "Verification of Seismic Adequacy of Mechanical and Electrical Equipment in Operating Reactors, Unresolved Safety Issue (USI) A-46," dated May 22, 1992, for the North Anna Power Station, Units I and 2, and the Surry Power Station, Units I and 2.
In this supplement, the staff requested that the licensee submit the following information within 120 days of the issue date of the supplement:
- 1.
A statement whether you commit 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 No. 2) for the.resolution of USI A-46.
In this case, any devia-tion from GIP-2, as supplemented by the SSER No. 2, must be identified, justified, and documented.
If you do not make such a commitment, you must provide your alternative for responding to* GL 87-02.
- 2.
A plant-specific schedule for the implementation of the GIP 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 implementation and submit the summary report within 3 years after the issuance of the SSER No. 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 US! A-46 as requested in the SSER No. 2.
The licensee's in-structure response spectra are considered acceptable for US! A-46 unless the staff indicates otherwise during a 60-day review period.
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In addition, the staff requested in SSER No. 2 that the licensee inform the staff, in the 120-day response, if it intends to change its licensing basis to reflect a commitment to the USI A-46 (GIP-2) methodology for verifying the seismic adequacy of mechanical and electrical equipment, prior to receipt of the staff's plant-specific safety evaluation resolving USI A-46.
EVALUATION With regard to Item 1, the licensee stated that, "As a member of SQUG, Virginia Electric and Power Company commits to use the SQUG methodology and commitments set forth in the GIP in their entirety. The SQUG methodology and commitments include the clarifications, interpretations, and exceptions identified in SSER-2 as clarified by the August 21, 1992, SQUG letter
. responding to SSER-2."
The licensee also stated that it "... will generally conform to the GIP implementation guidance, which comprises suggested methods for implementing the applicable commitments."
The licensee's response is unclear as to 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 under-standing 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 resolu-tion of USI A-46.
This understanding was the basis for the staff's position, which was stated in SSER No. 2, that if the licensee commits to use GIP-2 for the implementation of USI A-46, it must commit to both the SQUG commitments and the use of the entire implementation guidance provided in GIP-2, unless 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 who 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 No. 2 that if a licensee uses methods that deviate from the criteria and pro-cedures 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. 1 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 procedures for responding to GL 87-02.
In addition, on October 2, 1992, the NRC staff responded 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. 1 to GL 87-02.
The licensee should refer to the staff's position, as delineated in its October 2, 1992 response, on the SQUG letter.
L With regard to Item 2, the licensee stated that it will submit a summary report to the NRC summarizing the results of the USI A-46 program at North Anna Power Station, Units 1 and 2, by March of 1996, and at Surry Power Station, Units 1 and 2, by February of 1997.
Although these submittal dates exceed the 3-year response period requested by the staff, the licensee indicated that the extensions are necessary for the following reasons:
(1) the existing plant refueling outage schedule controls the SQUG walkdown schedule, (2) to complete the SQUG walkdowns, two refueling outages per unit are necessary, and the current refueling outage schedule spans more than three years, (3) USI A-46 is being integrated with the seismic IPEEE program which increases the intensity of activities and lengthens the time for preparation of walkdown packages and the final summary report, and (4) personnel limitations due to the licensee's intention to use its own engineers for performing the walkdowns at all four units.
In addition, the licensee indicated that the 1993 North Anna, Unit 1 steam generator replacment activities will further limit the personnel available for performing the USI A-46 walkdowns.
The staff finds that the licensee has provided adequate justification for its submittal dates, and therefore, the schedules are acceptable.
Based on our review of the licensee response and the staff positions delineated in the SSER No. 2, we conclude that the licensee response with respect to in-structure response spectra for North Anna is adequate and acceptable, and the in-structure response spectra included in the plant LB documents may be used for the resolution of the USI A-46 issue.
If the licensee intends to use the option of developing or using "median-centered" in-structure response spectra, the licensee is requested to inform the staff the approximate date by which such information will become available.
With respect to the same USI-46 issue for Surry, in compliance with the requirement of SSER No. 2, the licensee has provided the requested information as follows:
I.
- 2.
- 3.
- 4.
- 5.
- 6.
Housner spectra on soil site anchored to a peak ground acceleration level of 0.15g was used as input ground motions.
Five percent damping was used for obtaining in-structure spectra for service building, emergency diesel generator enclosure building, safeguards building, and containment spray pump house.
The mathematical models used were three-dimensional multi-mass representations.
Soil-structure interaction was evaluated using both a finite element method or a three-step analytical spring method.
The results from both analyses show good comparison.
The effect of increasing and decreasing the low strain shear moduli by 50% was evaluated for the soil-structure interaction.
Three orthogonal time-histories were used as ground motion input.
- 7.
The vertical response of the structure has been included in the analysis.
- 8.
The in-structure response spectra generated for the three soil cases were enveloped and then broadened by 15%.
Based on our review of the licensee response and the staff positions delineated in the SSER No. 2, we conclude that the licensee response with respect to Surry is adequate and acceptable. This conclusion is based on an assumption that the statements made in the submittal, including the procedures used in generation of the floor response spectra, correctly reflect the FSAR and other licensing basis. The staff may audit the process by which the in-structure response spectra were generated.
The staff agrees with the licensee that the in-structure response spectra so generated via the procedures and criteria described in the submittal can be used as "conservative design" spectra for comparing seismic capacity to seismic demand at Surry Power Station.
The licensee indicated that it intends to change its licensing basis methodology, via 10 CFR 50.59, for verifying the seismic adequacy of new, replacement, and existing electrical and mechanical equipment prior to receipt of a final plant-specific SER resolving USI A-46.
The staff recognizes that the licensee may revise its licensing basis in accordance with 10 CFR 50.59 to reflect the acceptability of the USI A-46 (GIP) methodology for verifying the seismic adequacy of electrical and mechanical equipment covered by the GIP.
However, if the licensee does not commit to implement both the SQUG commitments and the implementation guidance, and the licensee has not committed to any acceptable alternative criteria and procedures, then the staff does not believe that it is feasible, at this time, for the licensee to change its licensing basis in the manner described.
CONCLUSIONS The staff interprets the licensee's response to Supplement No. 1 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 licensee does not commit to implement the entire GIP-2, 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 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 response dated October 2, 1992, to the SQUG.letter.
Although the licensee's proposed implementation schedules exceed the 3-year response period requested by the staff, the licensee provided adequate justification for its schedules, and therefore, the schedules are acceptable.
The staff finds that the licensee's response regarding in-structure response spectra for both North Anna and Surry is adequate and acceptable.
The staff recognizes that the licensee may revise its licensing basis in accordance with 10 CFR 50.59 to reflect the acceptability of the USI A-46 (GIP) methodology for verifying the seismic adequacy of electrical and mechanical equipment covered by the GIP.
However, if the licensee does not intend to commit to fully implement both the SQUG commitments and the implementation guidance, or commit to an acceptable alternative criteria and procedures, then the staff does not find it is feasible, at this time, for the licensee to change its licensing basis in the manner described.
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OCT 02.
Mr. Neil Smith, Chairman Seismic Qualification Utility Group c/o EPRI 1019 19th Street, N.W.
Washington, DC 20036
SUBJECT:
NRC RESPONSE TO SEISMIC QUALIFICATION UTILITY GROUP (SQUG)
ENCLOSURE 2 Re:
Letter, N. Smith, EPRI, To J. Partlow, NRR, dated August 21, 1992, concerning USI A-46 Issues.
Dear Mr. Smith:
This is to acknowledge the receipt of the SQUG response to Supplement No. 1 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 that successful implementation of the entire GIP-2, supple-mented by the staff's SSER No. 21 by each SQUG licensee will result in cost-effective plant safety enhancement for their USI A-46 plants.
The staff also be.-lieves that the positions delineated in Supplement No. l to Gl 87-02 and SSER No. 2 are clear and correct, and should not be misinterpret-ed.
The staff's convnents 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.
Enclosure!
As stated Sincerely, Jt!\\?~lON Associate Director for Projects Office of Nuclear Reactor Regulation
e ENCLOSURE I.
NRC's Comments on the SOUG Letter of August 21. 1992:
I.
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 method, rather, it is an acceptable evaluation method, for USIA-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 purpose of the NRC regulations relevant to equipment seismic adequacy 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 from a licensee. Although you are correct in your statement 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 additional information received following a rejection or a question from the staff. To eliminate any potential misunder-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 will either state its *approval (or rejection) of the information provided, or indicate the time duration needed for the review of such information, prior to transmitting a follow-up response of acceptance (or rejection) to the licensee. This time duration 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 valid. The ANCHOR code does not consider the effects of base plate flexibility on the anchorage capacity.
- 4.
With respect to transfer of knowledge regarding major problems identified, and lessons learned, in the USI A-46 plant walkdowns and third-party reviews, we request that you include the NRC in the distribution of written communications to all member utilities in this regard, and inform the NRC staff of any planned workshops on A-46 implementation for possible staff participation.
II.
NRC's Comments on the Procedure foe Reviewing the GIP
- 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 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 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 GIP {Item 5, page 3 of the procedure), the staff's posi~ion on the issue of its response timing is identical to that delineated in the response to a licensee submittal of additional information
{refer to item 2 of NRC's Corrunents on the SQUG letter in this enclosure). This comment also applies to the section "LICENSING CONSIDERATIONS" on page 5 of the Attachment to the SQUG letter.
- 3.
With resp~ct 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.