ML20198E319
| ML20198E319 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 11/25/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20198E317 | List: |
| References | |
| REF-GTECI-A-46, REF-GTECI-SC, TASK-A-46, TASK-OR GL-87-02, GL-87-2, NUDOCS 9212070016 | |
| Download: ML20198E319 (3) | |
Text
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UNITED STATES ai NUCLEAR REGULATORY COMMISSION
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WASHINGTON. D.C. 20666
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SAFETY EVALVATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION 1
EVALUATION OF IOWA ELECTRI.G LIGHT AND POWER COMPANY'S l
120-DAY RESPONSE TO SUPPLEMENT NO. I 1
TO GENERIC LETTER 87-02 i
FOR DUANE ARNOLD ENERGY CENTER I
DOCKET NO. 50-331 INTRODUCTION i
j By letter dated September 21, 1992, the Iowa Electric Light and Power Company, l
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 Duane Arnold Energy Center (DAEC).
In this supplement, the staff requested that the licensee submit the following-information within l
120 days of the-issue datc of the supplement:
I 1.
A statement whether you commit to use both the Seismic Qualification Utility Group (SQUG) commitments and the implementation guidance i
provided in the Generic Implementation Procedure, Revision 2 (GIP-2), as-
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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 i
from GIP-2, as supplemented by the SSER No. 2, must be identified, l
justified, and documented, if you do not make'such a commitment, you i
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 l
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 l
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 USI A-46 as requested in_the SSER No. 2.
The licensee's in-structure response spectra are considered acceptable-for USI A-46 unless the staff l
indicates otherwise during a 60-day _ review period.
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 fnr verifying the seismic adequacy of mechanical and electrical equipment, pior to receipt of i
the staff's plant-specific _ safety evaluation resolving.USI A-46.
This report provides the staff's evaluation of the licensee's rer.ponse.
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EVALVATION With regard to item 1, the licensee stated that it "... commits to use the SQUG methodology as documented in the GIP Revision 2 (corrected February 14,1992) to resolve OSI A-46 at the Duane Arnold Energy Center (DAEC)." The licensee also stated, "lELP generally will be guided by other sections of the GIP which are not commitments, i.e., GIP implementation guidance, which comprises suggested methods for implementing the applicable commitments."
The licensee's response was clarified in the November 18, 1992 telecon that the licensee commits to implement both the SQUG commitments and the implementation guidance. The licensee stated that they intend to obtain prior NRC approval for any significant or programmatic deviations from the guidance portions of the GIP, but that for minor deviations they would not see( prior NRC approval.
However, the licensee would maintain the justifications for the minor deviations onsite.
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 re 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 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 tc satisfying the provisions of GL 87-02.
In addition, the attached letter provides the staff's response, dated October 2, 1992, to the August 21, 1992, SQUG 1etter. 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 October 2, 1992 letter for the staff's position on the SQUG 1etter.
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 DAEC by November 21, 1005, This submittal date is within the 3-year response period requested by '.n> staff and is therefore acceptable.
With ret w te S.em 3, the staff assessed the acceptability of the response to item II.?.2 3 o~ SSER No. 2.
The plant Safe Shutdown Earthquake (SSE) peak ground accd er dion (PGA) is 0.129 The Design Response Spectra (DRS) are based on the smoothed response spectra from the 1935 Helena, Montana, earthquake normalized to 0.129 PGA. An artificial time history (ATH) of the horizontal ground motion was developed from the 1940 El Centra earthquake.
The 5% spectrum developed from the ATH enveloped the DRS at all frequencies, with about 30% to 50% above the DRS between the frequencies of 2 to 8 Hz.
The in-structure response spectra (IRS) were generated by applying the ATH to the three-dimensional dynamic seismic models of the structures at the foundation levels. The licensee states that these spectra should be considered as
" conservative, design" IRS for verifying the equipment.
Though the DRS amplifications are low (compared to the conservative DRS defined in GIP-2),
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the ATH utilized for developing the IR5 compensates for the deficiency. Other l
parameters such as soil-springs, damping, mass and stiffness characteristics, are adequately considered. Overall, the amplifications and broadening of the IRS peaks appear to be reasonable, i
The staff concludes that the licensee response is adequate and acceptable, and that the IRS may be considered as " conservative, design" in-structure response spectra.
This conclusion is based on the assumption that the statements 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 l
process by which the in-structure response spectra were generated.
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 US! A-46 j
methodology prior to receipt of the staff's plant-specific SER.
[0NCLUS10NS i
The staff accepts the licensee's response to Supplement No. 1 to GL 87-02 as clarified by the November 18, 1992 telecon, committing to the entire GIP-2 including both the SQUG commitments and the implementation guidance.
a Additionally, the licensee should not merely follow the August 21, 1992, SQUG letter for implementing GlP-2, but should refer to the October 2, 1992 letter for the staff's response to the SQUG letter.
As indicated in SSER-2, 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 trovisions of GL 87-02.
The implementation schedule propv.,ed by the-licensee is within the 3-year response period requested by the staff in Supplement No I to GL 87-02 and is therefore acceptable.
j The licensee's in-structure response spectra have been reviewed and found to be adequate and acceptable.
The IRS may be considered as " conservative J
design" IRS for the resolution of USI-46 issues at DAEC.
I
Attachment:
Ltr. from J. Partlow, NRC, to j
N. Smith, SQUG, dated October 2, 1992 l
Principal Contributors: PYChen M McBrearty H Asher R Pulsifer Date: November 25, 1992
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ENCLOSURE 2
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Mr. Neil Smith, Chairman Seismic Qualification Utility Group c/o EPRI 1019 19th Street, N.W.
Washington, DC 20036
$UBJECT:
NRC RESPONSE TO SEISMIC QUALIFICATION UTILITY GROUP (SQUG)
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. 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 that successful implementation of the entire GIP-2, supple-s mented by the staff's SSER No. 2, by each SQUG licensee will result in cost-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-l 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.
l Sincerely, r
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l h db James G. Partlow Associate Director for Projects Office of Nuclear Reactor Regulation
Enclosure:
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ENCLOSURE 1.
NRC's Coments on the 50VG Letter of Auoust 21. 1992:
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 method, rather, it is an acceptable evaluation method, for USI 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 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 ycur 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 l
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 ccmplexity 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 Coments on the Procedure for Reviewina the GIP 1.
The staff supports SQUG's establishment of a Peer Review Panel com;nted of seismic experts since it should serve to enhance the reviu 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 nelp 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 I
members, who will be financed by SQUG/EPRI.
We would like to j
emphasize that staff's review of a proposed GIP change will receive thorough independent NRC evaluation and will be assessed on its merits.
i 2.
With respect to the NRC review and approval of the changes to the GIP (! tem 5, page 3 of the procedure), the staff's position on the issue of its response timing is identical to that delineated in j
the response to a licensee submittal of additional information (refer to item 2 of NRC's Comments on the SQUG letter in this i
enclosure).
This comment also applies to the section " LICENSING l
CONSIDERATIONS" on page 5 of the Attachment to the SQUG letter.
With respect to item 4, " Additional Restrictions," the text should 4
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i 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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