ML20128B823

Safety Evaluation Accepting Licensee 120-day Response to Suppl 1 to GL 87-02

ML20128B823
Person / Time
Site:	Millstone
Issue date:	11/23/1992
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20128B807	List: ML20128B803 ML20128B823
References
REF-GTECI-A-46, REF-GTECI-SC, TASK-A-46, TASK-OR GL-87-02, GL-87-2, NUDOCS 9212040097
Download: ML20128B823 (4)

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ENCLOSURE SAFETY EVALU4110N BY 1HE OFFICE OF NUCLEAR REACTOR REGUlAUQB EVALUATIQLOF THL120-DAY RESPONSE TO SUPPLEMENT NO. _L IQ_.SENERIC LETTER 87-02 NORTHEA';T NUCLEAR ENERGY COMPAfd tillLSTONE NUCLEAR POWER STATION. UNIT 1 DOCVET NO. 50-245 BACKGROUND By letter dated September 21, 1992, the Northeast Nu: lear Energy Company, the licensee, submitted their response to Supplement No. I to Generic letter 87-02 (GL 87-02), dVerification of Seismic Adequacy of Me;hanical and Electrical Equipnent in Operating Reactors, Unresolved Safety Issue (USI) A-46," dated May 22; 1992, for Millstone Nucl'.ar Power Station, Unit 1. In Supplement No.

I to GL 87-02, the staff requested that affected licenseas 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-2) for the resolution of USI A-46. In this case, any deviation from GIP-2, as supTlemented by the SSER No. 2, must be identified, justified, and docJmented. If you do not make such a comitment, 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 +uch that sach affected plant will complete its implementation and ;ubmit the summary report within 3 yeart 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 USI A-46 as requested in the SSER No. 2. The licensee's ta-structure response spectra are considered acceptable for USI A-46 unless the staff indicates otherwise dur:ng a 60-day review period.

In additian, the staff requested in SSER No. 2 that the licensees inform the staff in the 120-day response if they intend to char.ge their licensing basis to reflect a commitment to the USI A-46 (GIP-;) 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.

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r EVALUATION to comply With regard with the SQUGtocommitments item 1, the set licensee forth instated Revisionthat,

? of"NNECO the GIP, inc intend [s]luding the clarifications, interpretations, and exceptions identified in SSER-2 la order to satisfy GL 87-02." The staff recognizes that the licensee has chosen to implement GIP-2, including both the SQUG commitments aad the implemeatation guidance, for responding to GL 87-02. The staff finds that this is an i acceptable method to resolve USI A-46 at Millstone Nuclear Power Station, Unit 1.

The licensee indicated that they )lan to use existing anchorage evaltations, which were performed as part of tie Systematic Evaluation Program at Millstene Unit 1, as justification of seismic adequacy for USI A-46. The staff finds this approach acceptable provided that the anchorage evaluations previously performed meet the criteria and procedures approved by the staff in SSER No.2 (Section 11.4.4). The licensee also indicated that they plan to use existing seismic qualification test r(ports to demonstrate seismic adequacy for any equipment on their safe shutdown equipment lists (SSELs) which were previously qualified to IEEE 344-1975. The staff finds that this approach is acceptable for verifying equipment operability -but the licensee should also verify the seismic adequacy of the anchorage of this equipment in accordance with the criteria and procedures approved by the staff in SSER No. 2.

The licensee stated that they intend to u.e the Seismic Margin Mathods defined in the Electric Power Research Institute's (EPRI) Report NP-6041-SL, dated August 1991, as one option for the resolution of equipmcnt outliers. The methods defined in this report were intended to be used in conjunction with the seismic margin earthquake (Si-lE), and not with the safe shutdown earthquake (SSE) used in USI A-46 reviews. The criteria and methods defined in the EPRI report are less conservative than those defined in GlP-2. Therefore, the m9 hods defined in this report are, in general, not acceptable to the staff for resolving USI A-46 issues. ilthough the staff acknowledges that outlier resolution is beyond the scope of GIP-2, the staff generally endorses, with the clarifications provided in SSER No. 2, the types of outlier resolution described in Section 5 of GIP-2 (i.e., dynamic testing, engineer',ng analysis, physical repair, and replacement). As stated in Ser. tion 11.5 o. SSER No. 2, ,

"It is the responsibility of the utility to resolve outliers, tsing existing-procedures (e.g., plant-specific procedural controls and QA reqairements) as it would resolve any other seismic concerns." The staff will consider the application of somo of the criteria provided in EPRI Report NP-6041-SL, for the resolution of equipment outliers, on a case-by-case basis.

With regard-to item 2, the licensee stated that they will submit the Safe Shutdown Equipment List Reports, the Relay Evaluation Reports, and the Seismic Evaluation Reports to the NRC providing the results of the USI A-46 program at Millstone Unit 1,-within 180 days following the completion of Cycle #15 refueling outage (Winter 1995). Tiie proposed implementation schedule for Millstona Unit 1 excceds the 3-year response period. However, because of its current rerueling outage schedule, the staff finds that the proposed schedule is acceptable.

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t With regard to item 3, the licensee stated that it "will, at our option, use any of the methods recommended by Section 4.2 of the GIP, for defining in-structure response spectra (demand) for comparison to the SQUG Bounding Spectrum and the Gensric Earthquake Ruggedness Spectra," and that the licensee "will provide technical justification of the spectra generation methods where required by SSER No. 2, Section 11.4.2.4."

Since Millstone Unit 1 is identified as a Category 2 ISEP) plant in Generic Letter 87-02, Supplement No. 1, the staff finds that the licensee's response is adequate and acceptable, with one possible ex;eption, which is discussed below, regarding the licensee's response to SSER No. 2, Section 11.4.2.4.

Furthermore, if more than one set of in-structure response spectra appear in the licensing basis acuments, the more conservative set of spectra must be used to qualify for the definition of " conservative design" in-structure response spectra for the resolution of USI A-46 issues at Millstone 1. 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 NRC staff the approximate date by which such information will become available.

With respect-to SSER No. 2, Section 11.4.2.4, if the licensee intends to use the option or scaling IPEEE s;;ectra for use in USI A-46, then the licensee's res m nte is not acceptable since it did not provide the spectra generation meinods as requested in SSER No. 2. Therefore, if the licensee intends to use this option, it should submit the information roquested in SSER No. 2 as soon as possible for staff review.

The licensee indicated that, as part of the resolution of GL 87-02, they intend to change their licensing basis, via 10 CFR 50.59, to include the GIP methodologies as an option for demonstrating the seismic adequecy of new and replacement plant equipment. The staff recognizes thct the licensee may revise their 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, since the licensee intended to augment their licensing basis to include the GIP methodology as an o) tion for verifying seismic adequacy, rather than revise their licensing ) asis such that the GIP-2 would be the sole methodolog). the staff cautions that it is not acceptable to combine any part of GIP-2 with the current licensing basis methodologies such that it results in a less conservative approach than if GIP-2 or the current' licensing basis methodologies were applied separately.

CONCLUSIONS The staff finds that the licensee's commitment ta implement GIP-2, including the clarifications, interpretations and exceptions identified in SSER No. 2, to be an acceptable method for resolving USI A-46 at the Millstone Nuclear Power Station, Unit 1.

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l e-1 The staff finds that it is acceptable for the licensee to use previously performed anchorage evalt Lions for US! A-46, provided that the evaluations meet the criteria and procedures approved in SSER No. 2 (Section 11.4.4). The staff also finds that it is acceptable to use existing seismic qualification test reports to demonstrate operability for SSEL equipment which was qualified to IEEE 344-1975. -

The methods defined in EPRI Report NP-6041-SL are, in general, not acceptable to the etaff for resolving equipment outliers. However, the staff will consider the a) plication of some of the criteria provided in EPRI Report NP-6041-SL, for t1e resolution of equipment outliers, on a case-by-case basis.

The proposed implementition schedule for Millstone Unit 1 exceeds the 3-year response period. However, because of its current refueling outage schedule, the staff finds that the proposed schedule is acceptable.

The staff finds that the licensee's response concerning the in-structure =

response spectra is acceptable, with une possible exception where the licensee <

refers to SSER No. 2, Section !!.4.2.4. If the licensee intends to use IPEEE' s)octra for USI A-46, it should submit for staff review as soon as possible, tie information requested in SSER No. 2, Section 11.4.2.4.

The staff recognizes that the licensee may revise their licensing basis in accordance with 10 CFR 50.59 to reflect the acceptability of the US! A-46 (GIP) methodology for verifying the seismic adequacy of electrical and mechanical equipment covered by the GIP. However, since the licensees intend io augment their licensing basis to include the GIP methodology as an option for verifying seismic adequacy, rather than revise their licensing basis such that the GIP-2 would be the sole methodology, the staff cautions that it is -

not acceptable to combine any part of GIP-2 with the current licensing basis methodologies such that it results in a less conservative approach than if GIP-2 or the current licensing basis methodologies were applied separately.

Principal Contributors: P. Chen M. McBrearty D. Jeng

• rate: November 23, 1992

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