ML19275A548
| ML19275A548 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 09/28/1979 |
| From: | Parr O Office of Nuclear Reactor Regulation |
| To: | Proffitt W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| NUDOCS 7910040629 | |
| Download: ML19275A548 (5) | |
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',g NUCLEAR REGULATORY COMMISSION
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- E W ASHING T O N. D. C. 20555 o '.
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i Docket 50. 50-339
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Mr. W. L. Proffitt
'l Senior Vice President - Power Operations Virginia Electric and Power Company P. O. Box 26666 Richmond, Virginia 23261 s
Dear Mr. Prof fitt:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION To continue our review of your application for a license to operate the North Anna Power Station, Unit 2, additional information is required. The information requested is described in the Enclosure.
To maintain our licensing review schedule, we will need a completely adequate response to the enclosed request by October 12, 1979.
Please inform us after receipt of this letter of your confirmation of the above date or the date you will be able to meet.
Sincerely,
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Olan D. Parr, CDf Light Water Reactors Branch No. 3 Division of Project Management
Enclosure:
As Stated cc: See Next Page
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A Mr. W. L. Proffitt
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cc: Mr. Anthony Ganbaradel1a C1 arence T. 'Pi pps, Jr., Es q.
Of fice of the Attc" ey General 1700 Pennsyl vani a Avenue, fi.W.
11 South 12th Street - Room 308 Washington, D. C.
20006 Richmond, Virginia 23219
,,' Ca rrol l J. Sa vage, Es q.
Richard M. Foster, Esq.
1700 Pennsyl vania Avenue, f;.W.
211 Stribling Avenue
'Wa shington, D. C.
20006 Charlottesville, Virginia 22903 My James C. Dunstan Michael W. Maupin, Esq.
State Corporation Comission ilunton, Williams, Gay & Gibson Comonwalth of Virginia P. O. Box 1535 Blandon Building Richmond, Virginia 23212 Ri chmond, Vi rginia 23209 Mrs. June Allen Alan S. Rosenthal, Esq.
412 Owens Drive Atomic Sa fety and Licensing Appeal Itoard ibntwille, Alabana 35801 U.S. f;uclear Regulatory Comission Washington, D. C.
205b5 ter. James Torson 501 Leroy Michael C. Fa rrar, Esq.
Socorro, New Mexico 87801 Atomic Safety and Licensing Appeal Eoard U.S. fiuclear Regulatory Conmission Mrs. Margaret Dietrich Washington, D. C.
20555 Route 2, Box 568 Gordonsville, Virginia 22942 Dr. John II. Buc k Atomic Safety and Licensing Appeal Foard Willi an 11. Rodgers, Jr., Esq.
U.S. f;uclear Regulatory Comission Georgetown University Law Center Washington, D. C.
20555 600 fiew Jersey Avenue, fl.W.
Washington, D. C.
20001 Atomic Sa fety and Lice:1 sing Board ranel U.S. f,'uclear Regulatory Comission Mr. Peter S. liepp Washington, D. C.
20555
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Executive Vice President Sun Shipping & Dry Dock Company Mr. Michael S. Ki dd
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P. O. Box 540 U.S. fiuclear Regulatory Comission
,4 Chester, Pennsyl vania 19013 P. O. Box 128
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Spotsivania, Virginia 22553
'Mr. R. B. Bri ggs i..
Associata Director Dr. Paul W. Purdon 110 Evans Lane Department of Civil Engineering Oak Ridge, Tennessee 37830 Drexel University Philadel phia, Pennsyl vania 19104 i.
P00RORGNAL om
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Mr. W. L. Proffitt cc :
Dr. Lawrence R. Quarles
'N Apartment No. 51 e
Ke nda l-a t-Longwood
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Kennett Square, Pennsylvania 19348
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Mr. Irwin B. Kroot Ci tizens Energy forum P. O. Box 138 McLean, Virginia 22101 James B. Dougherty, Esq.
Potomac Alliance 1416 S Street, N.W.
Washington, D. C.
20009 s..
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1101 155
ENCLOSURE REQUESTFORADDITIONALINFORMA{lONg LEVEL MEASUREMENT ERRORS DUE TO ENVIRONMENTAL TEMPERATURE EFFECTS ON LEVEL INSTRUMENT REFERENCE LEGS T
t On June 22, 1979, Westinghouse Electric Corporation reported to NRC, a potential safety hazard under 10 CFR 21.
This report addresses errors gen-erated in the steam generator level indicati$n sensors following high energy pipe break accidents inside containment.
Further, the report implies that previous analyses of peak containment temperature and pressure may have been nonconservative. Breaks of this type can result in heatup of the steam gen-erator level measurement reference leg resulting in a decrease of the water column density with a consequent increase in the indicated steam generator water level (i.e., indicated level exceeding actual level).
IE Bulletin 79-21 includes further information on this problem and addresses appropriate actions which are to be taken by licensees of operating plants.
Applicants for an operating license are requested to submit a response to the following questions and to revise their safety analysis report consistent with this response.
1.
Describe the liquid level measuring systems within containment that are used to initiate safety actions or are used to provide post-accident monitoring information.
Provide a description of the type of reference leg used, i.e., open column or sealed reference leg.
2.
Provide an evaluation of the effect of post-accident ambient temperatures on the indicated water level to determine the change in indicated level relative to actual water level. This evaluation must include other sources of error including the effects of varying fluid pressure and flashing of reference leg to steam on the water level measurements.
3.
Provide an analysis of the impact that the level measurement errors in control and protection systems (2 above) have on the assumptions used
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in the plant transient and accident analysis.
This should include a review of all safety and control setpoints derived from level signals to verify that the setpoints will initiate the action required by the plant safety analyses throughout the range of ambient temperatures encountered by the instrumentation, including accident temperatures.
If this analyses demonstrates that level measurement errors are greater than assumed in the safety analysis, address the corrective action to be taken. The corrective actions considered should include design changes that could be made to ensure that containment temperature effects are automatically accounted for. These measures may include setpoint changes as an acceptable corrective action for the short term.
However, some form of temperature compensation or modification to eliminate or reduce temperature errors should be investigated as a long term solution.
I101 156
r 2-4.
Review Gnd indicate the required revisions, ar.necessary, of emergency procedures to include specific information obta'ined,from the review and evaluation of items 1, 2, and 3 to ensure that the operators are in-structed on the potential for and magnitude of erroneous level signals.
Provide a copy of tables, curves, or correction factors that would be applied to post-accident monitoring qystems that will be used by plant opera to rs.
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P00R OR lil 1101 157