ML20054H117
| ML20054H117 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 06/16/1982 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8206220590 | |
| Download: ML20054H117 (2) | |
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TENNESSEE VALLEY AUTHORITY
, j S h'Philifdodoc TENNESSEE 374oi l
U N rA. G EU;;.a 400 Chestnut Street Tower II l
82 JilN 18 A 9. al 9 Jur.s 16, 1982 BLRD-50-438/81-48 BLRD-50-439/81-51 U.S. Nuclear Regulatory Constission Region II Attn:
Mr. James P. O'Reilly, Regional Administrator 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303
Dear Mr. O'Reilly:
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - AUTOMATIC DIESEL START FROM AUXILIARY CONTROL ROOM - BLRD-50-438/81-48, BLRD-50-439/81 FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector R. V. Crlenjak on July 20, 1981 in accordance with 10 CFR 50.55(e) as NCR BLN BLP 8119 This was followed by our interim reports dated August 19, 1981 and January 19, 1982. Enclosed is our final report.
If you have any questions concerning this matter, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY DS h M L. M. Mills, Manager
(
Nuclear Licensing Enclosure cc:
Mr. Richard C. DeYoung, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 pCGl> C 8206220590 820616 W-h PDR ADOCK 05000438 S
PDR An Equal Opportunity Employer
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l ENCLOSURE BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 AUTOMATIC DIESEL START FROM AUXILIARY CONTROL ROOM NCR BLN BLP 8119 BLRD-50-438/81-48, BLRD-50-439/81-51 10 CFR 50.55(e)
FINAL REPORT Description of Deficiency Auxiliary Control System Criteria N4-50-D791, paragraph 4.2, requires that the design shall assume that evacuation of the main control room (MCR) can occur simultaneously or coincidently with the loss of offsite power. Standby AC Auxiliary Power System Criteria N4-RPD775A, paragraph 3 6.4, requires in part that "a main bus undervoltage (loss of offsite power) shall cause the diesel generator supplying standby power to that switchgear to start,
" The Solid State Control System (SSCS) control logic and hardware implementation does not implement these requirements. The Class IE medium voltage switchgear bus undervoltage signal intended in part to automatically start the diesel generator engine is inadvertently disabled by the diesel generator system SSCS logic when the main control room evacuation is initiated. Any subsequent required use of any or all of the diesel generators must be manually initiated from the auxiliary control room.
The apparent cause of the deficiency was a design error. TVA's Quality Assurance Branch is investigating the possible QA implications of this and other similar NCR's (see BLN QAB 8101).
Safety Implications Failure of the diesel generators to automatically start upon loss of offsite power would necessitate a manual start from the auxiliary control room. This requirement occurring simultaneously with the additional demand made of the operator during an evacuation of the main control room would unnecessarily complicate shutdown and/oc challenge safety components. Loss of offsite power and evacuation of the main control room are not mutually exlcusive events although the probability of simultaneous occurrence is extremely low. Failure to automatically start the diesel generators under these conditions could have jeopardized the safe operation of the plant as it would have affected the ability to safely shut down.
Interim Progress TVA has reviewed and corrected all affected drawings under ECN 1309 The date of completion for the design change was March 13, 1982. The corrected design was issued at that tine and properly reflects the design criteria.
Hardware installation required by design changes will be completed by fuel load.
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