ML20235D764
| ML20235D764 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 06/30/1987 |
| From: | Papanic G YANKEE ATOMIC ELECTRIC CO. |
| To: | Fairtile M NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM), Office of Nuclear Reactor Regulation |
| References | |
| TASK-03-06, TASK-3-6, TASK-RR FYR-87-67, NUDOCS 8707100292 | |
| Download: ML20235D764 (2) | |
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I Telephone (617) 872 8100 TWX 710 380-7619 YANKEE ATOMIC ELECTRIC COMPANY f
Inf 1671 Worcester Road, Framingham, Massachusetts 01701
. YANKEE
~
June 30, 1987 FYR 87-67 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Attention:
Mr. Morton Fairtile, Project Manager Project Directorate I-3 Division of Reactor Projects 1-11
Reference:
License No. DPR-3 (Docket No. 50-29)
Subject:
SEP Topic III-6, Reactor Pressure Vessel
Dear Mt. Fairtile:
The response characteristics of the reactor pressure vessel (RPV) under two different levels of scismic loads have been evaluated during the SEP.
In 1983 the RPV was analyzed using seismic loads represented by the Yankee Composite Spectrum (YCS).
In 1986, at the request of the NRC staff, the RPV was reanalyzed to the NRC cite specific spectrum.
The RPV at Yankee Nuclear Power Station is supported by the neutron shield tank (NST) support ring.
No slippage is possible at this interface.
The NST support ring, in turn, is supported by the reinforced concrete reactor support structure.
It is here that the potential for slippage may exist.
Our 1983 seismic analysis of the RPV concluded that the vessel would neither slide nor uplift under YCS loading. The staff stated in their February 3,1983 SER that this spectrum constitutes at least a lower bound SSE.
Consequently, Yankee is of the opinion that the potential sliding of the RPV is not a significant safety issue.
The 1986 analysis, using the NRC spectrum, concluded that RPV uplif t was negligible but could not prove conclusively that sliding of the NST support ring would not occur at this seismic level. Accordingly, we plan to initiate a program during the forthcoming operating cycle 19, the intention of which is to demonstrate acceptable RPV response under NRC spectra loading.
Failing that, we will develop a plant modification to insure acceptable RPV response under NRC spectra loads.
If the modification was determined to be necessary, we would plan to install this modification during the 1988 refueling outage.
8707100292 870630 0g(
ADOCK0500g9 PDR (fb P
rs United Stated Nuclear Regulatory Commission FYR 87-67 Page 2 June 30, 1987 Should we be unable to install this potential modification, Yankee will provide a justification for continued operation beyond the 1988 refueling start-up date.
The information provided herein was requested by the staff on June 29, 1987. This letter contains no new technical information; therefore, we expect it will have no effect on the scheduled issuance of the Topic III-6 cafety evaluation report.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY M
G. Papa ic, Jr.
Sr. Project Engineer - Licensing Yankee Project
/gbc cc: USNRC Region I USNRC Resident Inspector, YNPS I
i
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