ML20062F504
| ML20062F504 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 08/05/1982 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-82 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8208120066 | |
| Download: ML20062F504 (2) | |
Text
........
l P
TENNESSEE VALLEY AUTHORITY CH ATTANOOGA. TENNESSEE 37401 400 Chestnut Street Tower II August 5, 1982 BLRD-50-438/81-08 s
e BLRD-50-439/81-08 v
U.S. Nuclear Regulatory Comission Q
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 - SOLID STATE AC VOLTAGE RELAYS -
BLRD-50-438/81-08, BLRD-50-439/81 FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector M. Thomas on January 2, 1981 in accordance with 10 CFR 50.55(e) as NCR BLN BLP 8012. This was followed by our interim reports dated February 2, May 14, and September 11, 1981 and February 24, 1982.
Enclosed is our final report. We consider 10 CFR Part 21 to be applicable to this deficiency.
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 L. M. Mills, Manager Nuclear Licensing Enclosure cc:
Mr. Richard C. DeYoung, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Comission Washington, DC 20555 nic1:tCIAl. col],[,
8208120066 820805 I 6 d[
DR ADOCK 05000 An Equat Opportunity Ernployer
\\
J e
ENCLOSURE BELLEFONTE NUCLEAR PLANT UNITS 1 AND P SOLID STATE AC VOLTAGE RELAYS NCR BLN BLP 8012 BLRD-50-438/81-08, BLRD-50-439/81-08 10 CFR 50.55(e)
FINAL REPORT Description of Deficiency The solid state ac voltage type 27 (221B series) and type 47 (211F series) relays used on the 6.9 kV, Class 1E switchgear require a source of de control pcwer for proper operation. The present design configuration of the relays utilizes a contact from the undervoltage relay to energize an auxiliary relay upon detection of an undervoltage condition. The auxiliary relay initiates alarms and breaker trips. However, when do control power is lost and then restored (such as might accompany a bus transfer), the auxiliary relay will become energized long enough to initiate the supply feeder breaker trip sequence even though an actual undervoltage condition does not exist.
If this were to occur at a time when offsite power was not available and the source of power was the emergency onsite power source (diesel generator), this condition would lead to the inadvertent isolation of a 6.9 kV, Class IE, switchgear board.
In this instance, the boards would have to be manually reconnected. This deficiency occurred because the solid state relay supplied was not an exact functional duplicate of the electro-mechanical type relay TVA specified on the bid request.
The 6.9 kV switchgear was designed and supplied by Gould-Brown Boveri, h'estminster, Maryland.
Safety Implications This condition could lead to the inadvertent isolation of a 6.9 kV, Class IE, switchgear board.
If this were to occur at a time when offsite power was not available, the supply breaker would be locked out and the board would have to be reconnected manually. Therefore, this condition could have led to a situation whereby no ac power was available for a period of time until the board could be manually reconnected which could have adversely affected plant safety.
Corrective Action TVA has returned the deficient relays to the vendor. The vendor is in the process of factory modifying the internal circuitry of the type 27 (211B series) undervoltage relays to prevent them from dropping out on loss of dc biasing voltage. This modification will eliminate spurious trips when the l
de power supply is switched. The vendor has replaced the type 47 (211F series) with the type 47 (211N series). The vendor haa now developed the type 27 (211R series) and type 47 (211N series) relays which do not drop out on loss of de voltage.
Instruction manuals for the modified relays h'.ec tuer appr7ved by TVA. Expected completion d'fn fe" the mod ificat i nn and reinstallation of these relays is February 10, 1983 To prevent recurrence, the application of these relays at other TVA nuclear projects is being reviewed to determine if this condition exists..This review will be completed by February 26, 1983, and nonconformances written as required.