ML20235C844
| ML20235C844 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 06/30/1987 |
| From: | Whittier G Maine Yankee |
| To: | Murley T Office of Nuclear Reactor Regulation |
| References | |
| REF-GTECI-A-46, REF-GTECI-SC, RTR-NUREG-CR-4482, TASK-A-46, TASK-OR 8689L-LMO, GDW-87-137, GL-87-02, GL-87-2, MN-87-67, NUDOCS 8707090552 | |
| Download: ML20235C844 (2) | |
Text
-
MAIRE HARHEE 'ATOMICPOWER00MPARUe EDISON DRIVE avous,x. un,uE oa33s (207) 623-3521 June 30, 1987 MN-87-67 GDH-87-137 United States Nuclear Regulatory Commission Hashington, D. C.
20555 Attention:
Dr. Thomas E. Hurley, Director Office of Nuclear Reactor Regulation
References:
(a) License No. DPR-36 (Docket No. 50-309)
(b) MYAPCo Letter to USNRC dated March 24, 1986 (c) USNRC Letter to MYAPCo dated February 19, 1987 (Generic Letter 87-02)
(d) MYAPCo Letter to USNRC dated February 26, 1987 (e) USNRC Letter to MYAPCo dated March 26, 1987
Subject:
Maine Yankee Resolution of USI A-46 Gentlemen:
In response to your request in Reference (c) to conduct a review of the seismic adequacy of equipment against current seismic criteria, Maine Yankee believes that our participation in the NRC-sponsored Seismic Design Margins Program (SDMP) and receipt of a favorable Safety Evaluation Report (SER) provides adequate resolution of USI A-46 for the plant.
Ir. March of 1986, Maine Yankee agreed to participate in an NRC-sponsored SDMP.
Following the approach outlined in NUREG/CR-4482, this program used a combination of data collected from PRA studies, detailed plant walkdowns, experience data, and analysis to quantify the seismic capacity of the plant.
This review was performed by individuals knowledgeable of the A-46 Program, and utilized a combination of Seismic Qualification Utility Group (SQUG) caveats / criteria and conventional analyses.
This program demonstrated that, with limited upgrades, the seismic ruggedness for the plant is well beyond its original design basis.
Maine Yankee has provided, in Reference (d), a schedule for completion of these upgrades.
Following these upgrades, the High Confidence of Low Probability of Faihire (HCLPF) expressed in peak ground acceleration is estimated to be 0.27g.
gfo90552 t?70630 p
ADJCK 0$000309 AD (
O PDR I'
ll0 8689L-LM0
M AINE YANKEE ATOMIC POWER COMPANY United States Nuclear Regulatory Commission Page Two Attention:- Dr. Thomas E. Murley, Director MN-87-67 The results of the SDMP study are documented in a three volume report by Lawrence Livermore National Laboratory (NUREG/CR-4826, UCID-20948).
This report has been reviewed by the NRC and has received their concurrence on the technical findings.
Based on the NRC evaluation and our commitment to upgrade the items identified by the SDMP, the NRC concluded in Reference (e) that,
...all the issues associated with the design basis for MYAPS and hence the.
seismic design adequacy of the plant are considered resolved."
In order to ensure that seismic ruggedness is maintained, Maine Yankee has indicated in Reference (b), that new systems and their associated structures will be designed to 0.18g NUREG-0098 50th percentile with Systematic Evaluation Program allowables up to any interface with existing structures, systems, and components. The NRC agrees with this plan to ensure that future plant changes will not degrade the plant's existing seismic' ruggedness.
As a result of Maine Yankee's participat ' in the SDMP and.the NRC issuance of a favorable SER for the progra,. believe that Maine Yankee has more than met the intent of the proposed generic resolution of USI A-46 by virtue of the review having been performed at a seismic level greater than the design basis and by the inclusion of specified accident mitigation systems, structures, and components.
If you should have any further questions i
regarding the seismic adequacy of Maine Yankee, please feel free to contact me.
Very truly yours, MAINE YANKEE ATOMIC P0HER COMPANY b$W I
G. D. Whittier, Manager Nuclear Engineering and Licensing GDH/bjp 1
cc: Mr. Victor Nerses Mr. Hilliam-T. Russell Mr. Pat Sears Mr. Cornelius F. Holden l
8689L-LM0
.i