ML19326D695
| ML19326D695 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 06/27/1980 |
| From: | Sylvia B VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Harold Denton, Youngblood B Office of Nuclear Reactor Regulation |
| References | |
| 575, NUDOCS 8007030156 | |
| Download: ML19326D695 (3) | |
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VrnaturA Ex.ucrnic Axn Powen Co><rAxy RI C11>t O N D.VI HOIN I A C U u 61 June 27, 1980 Mr. lin old R.
Denton, Director Serial No. 575 Of fice of Nuclear Reactor Regulation N0/RMB:ms Attn:
Mr. B. J. Youngblood, Chief Docket No. 50-339 Licensing Branch No. 3 License No. NPF-7 Division of Licensing' U. S. Nuclear Regulatory Commission Washington, D. C.
20555 NRC REQUE"T FOR ADDITIONAL INFORMATION TECHNICAL $<CCIFICATION CHANGE REQUEST NORTH ANNA UNIT NO. 2
Dear Mr. Denton:
In our letter Serial No. 537 dated June 18, 1980, we requested that North Anna Unit No. 2 Technical Specification Table 3. 7-4 be revised to include addition-al safety related hydraulic snubbers as a result of recent reanalyses *.o bring the af fccted systems into compliance with FSAR comraiteents.
During.m iew of this matter, the NRC staff requested that Vepco explain why support modifica-tion recently made on Unit No.
2 Low Head Safety Injection (LHSI) systen piping was dif ferent from those modifications made on Unit No.
1.
These modifications were made to reduce the nozzle loads on the LHSI pumps.
The reasons for the dif fe rences in support modifications. was discussed in a telephone call with the NRC staff on June 24, 1980 and are documented in this letter.
The dif ferences can be explained in terms of the extent to which the loads were reduced on each unit and to the experience gained on Unit 2 during the reanalysis that was applied to Unit 1 before the start of its reanslysis.
he init a: goal for loading on the LHSI pump discharge nozzles for Unit 2 was a combineJ moment of 12,000 foot pounds.
Since significant reduction in in loading by modification of the seismic characteristics of the system did not appear to be feasible, the approach taken was to increase the flexibility of the piping for the different thermal conditions tha t the system experiences.
Hermal flexibility may be changed without affecting the seismic response of the system by simply replacing a rigid restraint with the appro-priate combination of a spring and snubber.
This procedure was done for Unit 2 at a total of ten support locations.
At some locations, due to design con-siderations, two snubbers in parallel we re used instead of one.
These parallel snubbers, acting in the same direc tion, have the same e f fect as a single snubber.
80070&O/5%-
[
e' Cx Ysac xir EttcTalC AND %WER COMPANY TO -
Mr.
Harold R.
Denton 3
Should you require any additional information, please contact us.
Very truly yours,
'[ [
B. R. Sylvia Manager - Nuclear Operations and Maintenance cc:
Mr. Ja'mes P. O'Reilly, Director
. Office of Inspection and Enforcement Region II i
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