ML19338F511
| ML19338F511 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 10/16/1980 |
| From: | Sylvia B VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Harold Denton, Youngblood B Office of Nuclear Reactor Regulation |
| References | |
| 849, NUDOCS 8010200446 | |
| Download: ML19338F511 (2) | |
Text
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e YIHOINIA l$LECTHIC AND l'OWEN CO SU% NY HIcIIxoNI),VIMOINIA nun 61 October 16, 1980 Mr. Harold R. Denton, Director Serial No. 849 Office of Nuclear Reactor Regulation N0/RMB Attention:
Mr. B. Joe 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
Dear Mr. Denton:
MULTIPLE STRUCTURE ARS CONCERN NORTH ANNA UNIT NO. 2 A meeting was held between Stone and Webster, Vepco, and members of the NRC staff on September 22, 1980_to discuss the results of the independent verifi-cation by the NRC of the pipe stress analysis performed by Stone and Webster on the North Anna Unit No. 2 Low Head Safety Injection Pump discharge piping.
During the meeting, the NRC staff requested the following additional informa-p tion that could act be adequately addressed during the meeting:
1.
The ef feet of containment growth, due to post-accident pressurization and thermal expansion, on the operability of the Low Head Safety Injection.(LHSI) pumps.
2.
A discussion of the conservatisms used in the generation and use of the Amplified Response Spectra (ARS) curves.
3.
A discussion of the relationship of a plot of the station ground response spectra to Curve No. 9 Reactor Containment Mat Response
@ el. 204 ft.,
supplied to you in our letter Serial No. 616 dated July 11, 1980.
The purpose of this letter is to respond to item No. I concerning the LHSI pump operability.
We are still in the process of. evaluating the concerns stated in item Nos. 2 and 3 and - will supply this information as soon as possible.
In response to your concern stated in item 1 above, we have reviewed LHSI Pump operability with respect to containment growth, due to post-accident pressurization ' and thermal expansion.
It is our conclusion that the opera-bility of. the pumps will not be af fected during the postuinted out of plumb periods associ.ated with the post-accident containment response.
- 8 410200 g
Mr. Ilarold R. Denton Vinois A Ettetnic AND Powea Coxrm To All LHSI pumps were optically aligned over the entire length of the pump, the icvelness of the can flange flat was within.005 inches, and elaborate field procedures were established to ensure the proper pump to can clearances at the seismic guide.
The precise alignment of the pumps confirms the fact that the pumps were installed plumb to within a very narrow tolerance.
Our conclusion considered the above information along with vendor allowable perpendicular misalignment of 0*-15',
which computes to approximately 2.5 inches at the can to pump flange. The calculated external containment growth is approximately 1 inch.
Knowing the strict and precise installation tech-niques followed to ensure plumbness of the pumps, and the vendor allowable perpendicular misalignment, it can be seen that misalignmr created by post-accident imposed loads i til not exceed allowables.
Since the vendor's allowables for perpendicular misalignment will not be exceeded, we have concluded that the pump will remain operable during the period of containment growth following the postulated accident.
If you have any questions or require additional information on this matter, please contact us.
Very truly yours, bl,
.u
/.
B. R. S Ivia nager - Nuclear Operations and Maintenance RMB/smv:SM2 cc:
Mr. Robert A. Clark, Chief Operating Reactors Branch No. 3 Division of Licensing Washington, D. C.
20555 Mr. James P. O'Reilly, Director Office of Inspection and Enforcement
-Region II-Atlanta, Georgia 30303
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