ML20198D312
| ML20198D312 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 05/08/1992 |
| From: | Engle L Office of Nuclear Reactor Regulation |
| To: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| TAC-M82916, TAC-M82917, NUDOCS 9205200091 | |
| Download: ML20198D312 (4) | |
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UNITED STATES 5
NUCLEAR REGULATORY COMMISSION -
o WASHINoToN. o.C. 20086 May 8, 1992 f
Docket Nos. 50-338 and 50-339 Mr. W. L. Stewart--.
S::nior Vice President - Nuclear Virginia Electric and Power Company 5000 Dominion Blvd.
Glen Allen Virginia 23060
Dear Mr. Stewart:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION/ SETTLEMENT MONITORING PROGRAM FOR CLASS 1 STRUCTURES / PIPE STRESSES DVE TO DIFFERENTIAL SETTLEMENT -
NORTH ANNA-POWER STATION, UNITS 1 AND 2 (NA-1&2) (TAC N05. M82916
.AND M62917)
Regarding the subject as noted above, we questioned the adequacy of p'ipe modM s used for stress calculations, including the use of soil spring constants,-spacing of springs, and anchor stiffness.
By letter dated September 29, 1989, you responded to this matter by stating that a-two-to-ten fold increase or decrease of the anchor translational-stiffness values would
. result in a less than 1% change of the critical stress levels.
However, it is not clear in your September 29, 1989 response that the effect of the variation of the anchor rotational stiffness values was evaluated as.part of your response.
It-is our position that rotational stiffness could significantly influence the results of pipe stress-levels. Therefore, a parametric study should be performed for the-effects of anchor rotation as well as other pertinent parameters,-including soil spring effects, and-the results of this study should be_used to determine the~ acceptability-of. pipe stress levels.
Based on ourzreview of your. submittal dated October 2, 1989, our concerns, as delineated above, sdll remain and a request for additional information, provided in the enclosure-to this lettcr,.is needed ir! order for us to complete our review of this matter.
By telecopy dated April-21, 1992, you were provided in-draft form our concerns and the request for additional information as provided in the enclosure to
- this letter. We requect that your response be provided as quickly as possible in order that we can complete our review of your October 2,1951 submittal by
-May 30,-19o2.
Fin &lly,'any correspondence regarding these matters should
' identify TAC Nos. M82916 and M82917.
WIC FILE CENTER COPY 9
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Mr. W. L. Stewart May 3,1992 This requirement affects fewer than 10 respondents and, therefore, is not subject to Office of Management and Budget review under P.L.96-511.
Sincerely,
/s/
Leon B. Engle, Project Manager Project Directorate 11-2 Division of Reactor Projects - 1/11 Office of Nuclear Reactor Regulation cc:
See next page Q'~'"lBUTIQN:
Docket file P122 NRC & Local PDRs PDil-2 RDG file SVarga Glainas HBerkow LEngle DMiller OGC ACRS (10)
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JNorberg o'FicE t/i!PAlj-2 PM:PDl 4 D:PJII-2 NAME i
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92 56/92
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DATE OfflCIAL RECORD COPY FILENAME: NA82916A.LTR I-1
Mr. W. L. Stewart North Anna Power Station Virginia Electric & Power Company Units 1 and 2 cc:
Mr. William C. Porter, Jr.
C.M.G. Buttery, M.D., M.P.H.
County Administrator State Health Commissioner Louisa County Office of the Commissioner P.O. Box 160 Virginia Department of Health Louisa, Virginia 23093 P.O. Box 2448 Richmond, Virginia 23218 Michael W. Maupin, Esq.
Hunton and Williams Regional Administrator, RII P.O. Box 1535 U.S. Nuclear Regulatory Commission Richmond, Virginia 23212 101 Marietta Street, N.W., Suite 2900 Atlanta, Georgia 30323 Dr. W. T. Lough virginia State Corporation Commission Mr. G. E. Kane, Manager Division of Energy Regulation North Anna Power Station P.O. Box 1197 P.O. Box 402 Richmond, Virginia 23209 Mineral, Virginia 23117 Old Dominion Electric Cooperative Mr. J. P. O'Hanlon 4201 Dominion Blvd.
Vice President - Nuclear Operations Glen Allen,_ Virginia 23060 Virginia Electric and Power Company 5000 Dominion Blvd.
Mr. E. Wayne Harrell Glen Allen, Virginia 23060 Vice President - Nuclear Services Virginia Electric and Power Co.
Mr. Martin Bowling 5000 Dominion Blvd.
Manager - Nuclear Licensing Glen Allen, Virginia 23060 Virginia Electric and Power Co.
5000 Dominion Blvd.
Glen Allen, Virginia 23060 Office of the Attorney General Supreme Court Building 101 North 8th Street Richmond,-Virginia 23219 Senior Resident Inspector North Anna ~ Power Station U.S. Nuclear Regulatory Commission Route 2. Box 78 Mineral, Virginia 231172
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ENCLOSURE Recuast For Additional Informa112n North Anna Power Station. Units 1 & 2 Qocket Nos. 50-330 and 50-339 Pine Stress Due To Differential Settlement 1,
Vertical, "translational" differential settlements which are considered as boundary conditions would impose a significent influence on the buried pipe stresses, if anchor rotations are restrained.
This fact should be const* red in the parametric study of the pipe stress calculation.
2.
Currently there is little margin existing to absorb any additional p'pe stress.
Therefore, complete pipe stress calculations incorporating the above mentioned parametric study and the croposed new TS permissible differential settlements should be submitted ror staff review. The submittal should include a justification of the pipe configuration used for analysis.
3.
Without assurance that the stresses of the buried pipes have been properly calculated, and in light of the potential significant reduction of the margin of safety as a result of the preceding differential settlements, the staff questions the validity of the licensee's 10 CFR 50.92(c) evaluation.
4.
The acceptance of the above stress calculation is contingent upon the staff acceptance of the survey measurenents of the survey points, including but not limited to survey points 113 and 117, in connection to total and differential settlements.
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