ML20033C074
| ML20033C074 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 11/10/1981 |
| From: | Starkey R CAROLINA POWER & LIGHT CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| RSEP-81-1783, NUDOCS 8112020633 | |
| Download: ML20033C074 (2) | |
Text
e f REGION.
A W GEOpdf, Carolina Power & Light Company y;NOVI3 a8. p H. B. ROBINSON STEAM ELECTRIC PLANT Post Office Box 790 Hartsville, South Carolina 29550 NOV101981 Robinson File No:
2-0-4-a-3 Serial: RSEP/81-1783 to
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Mr. James P. O'Reilly Q
[
[f Director of Regulatory Operations f (
Bi U. S. Nuclear Regulatory Commission b,,_ Og J
7$f 4
l Region II y
101 Marietta Street, Northwest
.j kA8 Atlanta, Georgia 30303
^b y
N H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-261 LICENSE NO. DPR-23 INFORMATION REPORT TEST FAILURE OF "B" REACTOR TRIP CIRCUIT BREAKER
Dear Mr. O'Reilly:
This report is being submitted as an information report.
While performing routine Periodic Test No. 19B (Reactor Protection Logic Tra'.n B) on September 23, 1981, "B" Reactor Trip Circuit Breaker (TCB) failed to trip when the trip signal was initiated. The breaker did trip during the racking out process for closer inspection. The breaker was inspected and found to have the undervoltage trip device in the trip posi-tion.
Act:>a Taken "B" Reactor TCB was declared inoperable at 1325 hours0.0153 days <br />0.368 hours <br />0.00219 weeks <br />5.041625e-4 months <br /> on September 23, 1981 and removed from its cubicle.
"A" Reactor Bypass TCB was removed from its cubicle, installed inplace of "B" Reactor TCB and tested success-fully. PT-19B was completed satisfactory at 1618 hours0.0187 days <br />0.449 hours <br />0.00268 weeks <br />6.15649e-4 months <br />.
"A" Reactor Trip Breaker had been demonstrated operable during PT-19A at 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br /> on September 23, 1981.
Cause Description and Analvsis Subsequent inspection and testing of "B" Reactor TCB revealed noticeable wear on the operating mechanism roller lever. This part was re g.g O oookg bA PDR S1 e i
.s Letter to Mr. James P. O'Reilly Serial: RSEP/81-1783 Page 2 but again failed upon test.
The manufacturer's service representative (Westinghouse) was brought onsite to assist in the determination of failure mode and repair of the breaker. After considerable testing and inspection, the cause of failure was determined to be the under-voltage (UV) trip device. The UV device exhibited a loss of spring tension and resultant binding which is attributed to normal wear.
This accounted for the initial breaker condition (i.e., UV device in tripped position, breaker untripped) in that the UV device lacked sufficent spring force to operate the breaker trip mcchanism. The service representative replaced the UV device; the breaker was tested satisfactorily. The breaker was returned to service on September 30, 1981 in the place of "A" Reactor Bypass TCB.
At no time was the plant operated in a less conservative condition than allowed by the Technical Specifications, and the installed Reactor TCB's were always capable of respondir.g to both automatic and manual trip signals. This failure is considered an isolated event of component failure, and no further action is considered necessary. This item has been evaluated pursuant to 10CFR21 and is not considered reportable.
Should you have any questions regarding this special report, please contact me.
Very truly yours, s
kbbbl j
R. B. Starkey, r.
General Manager H. B. Robinson S.E. Plant HTC/tm cc:
R. A. Hartfield (3)
V. Stello (40)
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