ML20128C532
| ML20128C532 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 04/25/1985 |
| From: | Hufham J TENNESSEE VALLEY AUTHORITY |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8505280321 | |
| Download: ML20128C532 (2) | |
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p, TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 374o1 400 Chestnut Street Tower II Y
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April 25, 1985 4
BLRD-5043842-51 8
BLRD-5043942-46
- 47E
' U.S. Nuclear Regulatory Canmission Region II Attn:
Dr. J. Nelson Grace, Regional Adninistrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
Dear Dr. Grace:
BELLEFWTE NUCLEAR PLANE LNITS 1 AND 2 - DEFICIENCY IN UNIERVCLTAE PROTECTION DURING AN ACCIIENT - BLRD-5043842-51, BLRD-5043942 FINAL EPORT The subject deficiency was initially reported to NRC-OIE Inspector R. V. Crlenjak on July 27, 1982 in accordance with 10 TR 50.55(e) as NG BLN EEB 8205. This was followed by our interim reports dated August 25 and November 19, 1982, January 17 and September 15, 1983 and April 17 and October 11, 1984.
Enclosed is our final report.
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If you.have any questions concerning this matter, please get in touch wLth R. H. ~ Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY
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. W. Hufham, Manager Licensing and Regulations Enelosure oc (Enclosure):
Mr. James Taylor, Director Office of Inspection and Enforcement U.S. ' Nuclear Regulatory Canaission Washington, D.C.
20555 F
Records ' Center Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 8505280321 850425 PDR ADOCK 050 B
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- An Equal Opportunity Employer
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BELLEFWTE NUCLEAR PLANT UNITS 1 AND 2 DEFICIENCY IN UNIER71TAE PROTECTICN DURING AN ACCIIENT NCR BLN EEB 8205 BLRD-50-438/82-51, BLRD-50-439/82-46 10 TR 50.55(e)
FINAL REPORT Description of Deficiency During a review, it was determined that the present design of the additiomi level of tndervoltage or overvoltage protection does not fully comply with the requirements as stated in Bellefonte Nuclear Plant (BLN) Final Safety Analysis Report-(FSAR) question 430.38 and the guidelines in NRC branch technical position -(BTP) PSB-1. Misinterpretation of these requirements by TVA caused the present design not to consider a degraded voltage concurrent with an accident. Because of this misinterpretation, the time delay selected
.to initiate separation of the class 1E distribution system from the degraded offsite power system will not permit connection to the alternate or emergency feeder soon enough to ensure adequate voltaps' for the required safety motors.
Safety Inclications Excessive delay in separating safety-related motors from a degraded voltage source and connecting to an emerpncy feeder could allow voltage levels to degrade sufficiently to cause motor speeds to drop below the optimtm point for the reestablishnent of nominal voltage levels. This could result in additional delay in starting the safety-related motors necessary to mitigate a design basis accident (DB A). As such, this condition could have adversely affected plant safety.
Corrective Action TVA has revised its design criteria, N4-RPDT75A, to incorporate the design modifications necessary to satisfy the NRC Staff position on degraded voltage protection and the voltap and time-delay set points for the degraded voltage design have been included in the BLN ao auxiliary power systen review, D288-G10190 RP.
Design changes and field modifications have been completed 4
throtsh engineering change notice (EG) 1559 Because this problen was caused by a misinterpretation of the original NRC Staff requirements by TVA (the NRC has published a clarification of the requirements in BIP PSB-1) and TVA has incorporated the correct interpretation in the plant design criteria, no further action to prevent recurrence is required.
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