ML19269D137
| ML19269D137 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 02/22/1979 |
| From: | Brown S VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 300B, NUDOCS 7902270374 | |
| Download: ML19269D137 (1) | |
Text
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.q0 Vepco Mr. James P. O'Reilly, Director Serial No. 300B Office of inspection & Enforcemen{ebruary 22, 1979 PSE&C/MLM:adw:me
' U. S. Nuclear Regulatory Comission Region II Docket No. 50-339 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303
Dear Mr. O'Reilly:
On Januar 10CFR50.55(e)y'31,1979, Vepco submitted the final report as required by and 10CFR21 to NRC Region II regarding the neutron stream-ing fix for Unit 2 (Serial No. 300A). Subsequent to this submittal, Westinghouse has sent Vepco additional infomation concerning the effects of LOCA on tP loads to the fuel assemblies and reactor core internals which we believe is pertinent to your evaluation of the supplementary neu-tron shield.
The fuel assembly impact loads have increased from those reported in FSAR Appendix SA by approximately 10%. This change alone would reduce t.ie margins previously reported in the FSAR; i.ortever, the loads are still less than the allowable values. Recent testing on fuel grid-impact strength has resulted in We.itinghouse increasing the allowable loads by spproximately 25% above those reported in Appendix EA. Tnese new allowables have been reported to the NRC on the diablo Canyon plant. Nhen using the new allow--
able load along with the revised actual impact loads, the revised margin is actually higher than that previously reported in Appendix 5A. The "better estimate" factor of safety of 1.76 reported in the FSAR would now be about 1.97.
The limiting stress on the reactor vessel internals at the core barrel
. girth weld have decreased from that which was previously reported in Appendix 5A. This is due to the time phasing of the component forces.
In sumary, the proposed supplementary neutron shield for Unit 2 does not change the conclusion previously established in Appendix SA of the North Anna FSAR.
Please contact me if further information is required.
0 'k'" Y 5*
l j g) 7,(dac W C. Brown, Jr.
Seni Vice Presiden ower Stat on Engineering a Construction cc: Mr. John G. Davis, Acting Directo
~0ffice of Inspection & Enforcement Mr. Harold R. Denton, Director hk Office of Nuclear Reactor' Regulation N
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