ML19263E028
| ML19263E028 | |
| Person / Time | |
|---|---|
| Issue date: | 04/17/1979 |
| From: | Kerr G NRC OFFICE OF STATE PROGRAMS (OSP) |
| To: | Sechrest M AFFILIATION NOT ASSIGNED |
| References | |
| FRN-43FR56677, RULE-PR-20 NUDOCS 7905250038 | |
| Download: ML19263E028 (1) | |
Text
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UNITED STATES j
NUCLEAR REGULATORY COMMISstON
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W A SH ING TO N, 0. C. 20555 l-nj,5 May es, 1979 Decket Nos. 50-250 a-9 and 50-281 t'r..i. L. Prof fitt Senior Vice President - Pcwer Virginia Electric and Power Company Post Office Box 26666 Richmond, Virginia 23261 Cear f'r. P ro f fi tt:
The purpose of tnis letter is to state our position regarding the use of soil structure interaction for the seismic pipestress analyses being performed for Surry Power Station, Units 1 and 2.
Based on the results of the information you provided by your letter dated May 24, 1979 in response to our May 18, 1979 letter and in other meetings, we confirm 'that soil structure interaction methodology may be used for Surry provided that seismic stresses calculated are increased by a factor of 1.5.
This factor applies to the seismic stresses derived from amplified response spectra using 1% damping.
It is further acknowledged that certain individual dnalyses may require Consideration on a case by Case basis.
The earthquake of primary safety concern is the SSE.
However, due to the nonlinearities of tne soil which are considered in the soil structure interaction analyses, the stiffness of the subgrade ic a function of the earthquake level.
Since the floor response spectra are sensitive to tne stiffness of the subgrade, they too are dependent en the earthquake level.
Therefore, it is requested that the following two points De acdressed:
1.
Discuss in detail why it can be concluded that the piping analyzed for the SSE condition will safely withstand all earthquakes up to and including the SSE.
2.
For any piping systems which meet SSE requirements but do not meet the FSAR OBE design requirements, provide the level of earthqucke for which the FSAR 03E design requirements are met.
Sincerely, Jk!'
4 Ei senan, De:u y Dire: tor 3.
2.
Civisicr cf ^.peratir,g Raa:: ors 2217 s33 peso O
Mr.
'a.
L. Proffitt Virginia Electric and Power Company cc:
Mr. Micnael n'. Maupin Hunt n and Williams os Of fice Box 1535 c
Ricn Onc, Virginia 23213 Saem Li:rary College of dilliam and Mary Williamsourg, Virginia 23185 Jonalc J. Burke
- 3. 'aclear Regal atory Cct.11ssion Region !I Office of Inspection and Enforcement 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 2217 334 9
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