ML19242B492
| ML19242B492 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco, North Anna |
| Issue date: | 06/26/1979 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Proffitt W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| NUDOCS 7908080609 | |
| Download: ML19242B492 (4) | |
Text
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4 NUCLEAR REGULATORY COMMISSION 2
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.E W ASHING TO N,0. C. 20555
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June 26,1979
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Docket Nos. 50-338 & 50-339 Mr. W. L. Proffitt Senior Vice President - Power Operations Virginia Electric & Power Company P. O. Sox 26666 Richmond, Virginia 23261 Gentl emen:
Racently, because of operator error, an inadvertent reactor scram and safety injection occurred durirg monthly surveillance tests of the safeguards. system at a PWR facility.
At the time of the event, train "A" of the safeguards system had been placed in " test", and the operator, in addition to inserting a high steam flow signal required by the test, inadvertently incorrectly in-serted a low steam pressure signal.
This action resulted in a low steam pressure signal (signifying a main steam line break) in train "A" which initiated main steam isolation valve (MSIV) isolation and a reactor s c ram.
One MSIV, however, did not close because of a ' valve solenoid failure.
The re.ultant differential pressure between two steam lines initiated a safety injection signal from train "B".
In the ensuinq events several more equipment failures occurred.
One feedwater regulation valve failed to close because of another solenoid failure.
The steam driven auxiliary feedwater pump tripped on overspeed and one of the steam generator atmospheric relief valves failed to fully reseat upon closure.
This occurrence, with its ensuing sequence of events, is of concern to the NRC staff because of the serious questions that are raised due to the multiple equipment failures and whether a very real problem could exist that has not been analyzed. For example, the potential for common mode failures (in this case two apparently independent solenoid va ve failures) should be investigated to ensure that a problem does l
nct exist which could negate the criteria assumed in your previous accident analyses or which could lead to an overall reduction in system rel ' abil i ty.
This occurrence is also of concern because of an apparent sense of complacency towards periodic surveillance requirements in general and on engineered safeguards systems in particular which has all too often resulted in inadvertent reactor scrams and safety injection system actuations.
From the standpoint of unnecessary challenges to the reactor trip and the safeguards systems and the imposition of unnecessary themal stress cycles on reactor coolant system and its components, this is undesirabla.
524 799 7908080hd
. June 26,1979 You and your plant supervisors should review the events described in this letter, to determine whether similar errors have occurred or could occur at your facility and whether the potential exists for a problem associated with occurrences that you have not previously considered.
In addition, it is requested that management policies and procedures be reviewed and strengthened as necessary to assure that multiple equip-ment failures in safety-related systems will be vigorously pursued and analy:ed to identify potential failure modes not previously considered that could lead to a significant reduction in the ability of safety systems to function as required.
Finally, you are requested to review your engineered safety system surveillance procedures to determine whether appropriate cautions are incluted and to ensure that plant operators and supervisors are aware of the importance of avoiding challenges to the protective features of your facility.
Within 30 days of receipt of this Ic:.ter, please submit, in accordaace with 10 CFR 550.54(f) of the Comm'.sion's regulations, the results of these re/iews.
In addition to licensing reviews of these mutters, we hav: requested that the NRC's Office of Inspection and Enforcement perform a followup inspection on these matters in the near tcture.
- incerely, s'
h ) \\, f O N A L Q arreTT. Eisenhut, Acting Di rector Division of Operating Reactors Office of Nuclear Reactor Regulation cc: See next page 524 300
Mr. W. L. Prof fitt cc:
Mrs. James C. Arnold John J anzer, Esq.
P. O. Box 3951 Pepper, Haui1 ton & Scheetc Charlottesville, Virginia 22903 123 South Broad rect Philadelphia, fent..j
- lW)
Mr. Anthony Gambaradella Of fice of the Attorney General Clarence T. Kipps, Jr., Esq.
11 South 12th Street - Room 308 1700 Pennsylvania Avenue,. f;.W.
Richmond, Virginia 23219 Washington, D. C.
20006 Carroll J. Savage, Esq.
Richard M. Foster, Esq.
1700 Pennsylvania Avenue, fi. W.
211 St rib'ing Avenue Wasnington, D. C.
20006 Charlot tesville, Virginia 22903 Mr. James C. Dunstan Michael W. Maupin, Esq.
State Corporation Cormission Hunton, Williams, Gay & Gibson Cocmonwealth of Vi rg i n i a P. O. Box 1535 Blandon Building Richmond, Vi rginia 23212 Richmond, Virginia 23209 l'rs. June Allen 412 Owens Drive Huntsville, Alabama 35801 Mr. James Torson Al an S. Rosenthal, Esq.
501 Leroy Atomic Safety and Licensing Socorro, New Mexico 87801 Appeal Board U.S. f;uclear Regulatory Conmission Mrs. Margaret Dietrich Washington, D. C.
20555 Route 2, Box 568 Gordonsville, Vi rginia 22942 Michael C. Fa rrar, Esq.
Atonic Safety and Licensing William H. Rodgers, Jr., Esq.
Appeal Board Georgetown University Law Center U.S. Nuclear Regulatory Commission 600 New Jersey Avenue, N.W.
Wash ingtor., D. C.
20555 Washington, D. C.
20M1 Dr. John H. Buck Mr. Peter S. Hepp Atomic Safety and Licensing Executive Vice President Appml Board Sun Shipping & Dry Dock Company U.S. f!uclear Regulatory Cocriission P. O. Box Sf0 Washington, D. C.
20555 Chester, Pennsylvania 19013 Mr. R. B. Briggs Atomic Safety and Lic ensing Associate Director Board Panel 110 Evans Lane U.S. f;uclear Regulatory Commission Oak Ridge, Tennessee 37830 Washington, D. C.
20555 524 301
u Mr. W. L. Proffitt cc:
Mr. Michael S. Kidd U. 5. Nuclear Regulatory Commission P. O. Box 128 Spots 1vania, Virginia 22553 Dr. Paul W. Purdom Department of Civil Engineering Drexel University Philadelphia, Pennsylvania 19104 Dr. Lawrence R. Quarles Apartment No. 51 Kenda l-a t -Longwood Kennett Square, Pennsylvania 19348 Mr. Irwin B. Kroot Ci t izens Energy Forum P. O. Box 138 McLean, Vi rginia 22101 James B. Dougherty, Esq.
Potomac Alliance P. O. Box 9306 Washington, D.C.
20005 3 /,4 JUc I~
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