ML20028F393

Ro:On 821220,reactor Trip Circuit Breaker a Failed to Trip When Trip Signal Initiated.Caused by Sticking Undervoltage Relay.Relay Replaced.Contacts Cleaned

ML20028F393
Person / Time
Site:	Robinson
Issue date:	01/19/1983
From:	Starkey R CAROLINA POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
BSEP-83-62, NUDOCS 8302010319
Download: ML20028F393 (2)

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Cp&L Carolina Power & Light Company

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H. B. ROBINSON STEAM ELECTRIC PLANT POST OFFICE BOX 790 HARTSVILLE, SOUTH CAROLINA 29550 JANI J 1983 Robinson File No: 13510 Serial: RSEP/83-62 Mr. James P. O'Reilly ,

Regional Administrator u U. S. Nuclear Regulatory Commission u Region II _

101 Marietta Street, Suite 3100 .x -

Atlanta, Georgia 30303

• r H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 F3 DOCKET NO. 50-261 - -

LICENSE NO. DPR-23 .c.

INFORMATION REPORT CI TEbT FAILURE OF "A" REACTOR TRIP CIRCUIT BREAKER

Dear Mr. O'Reilly:

This report is being submitted as an information report.

While performing routine Periodic Test (PT) No. 19A (Reactor Protection Logic Train A) on December 20,1982, "A" Reactor Trip Circuit Breaker (TCB) failed to trip when the trip signal was initiated.

I Action Taken "A" Reactor TCB was declared inoperdole at 1450 hours0.0168 days <br />0.403 hours <br />0.0024 weeks <br />5.51725e-4 months <br /> on December 20, 1982, and removed from its cubicle. "B" Reactor Bypass TCB was removed f rom its cubicle, installed in place of "A" Reactor TCB, and tested successfully. Periodic Test PT-19A was completed satisfactorily, and "B" Reactor TCB was demonstrated operable during PT-19B at 1709 hours0.0198 days <br />0.475 hours <br />0.00283 weeks <br />6.502745e-4 months <br /> i on December 20, 1982.

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_Cause Description and Analysis Sub sequent inspection and testing of "A" Reactor TCB revealed that the undervoltage relay appeared to be sticking. The relay was removed f rom the breaker, cleaned, lubricated, and found to operate properly.

8302010319 830119 .

l PDR ADOCK 05000261 0 PDR ;ggqaAL COPE l

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.A* Lstter to Mr. Jrm:c P. O'Railly Strici: RSEP/83-62 Page 2 However, a new undervoltage relay was installed in the breaker. It is believed that the reason the relay failed to operate was due t.o improper lub rica tion. Additionally, the inspection of the breaker mechanism revealed that the operating links for A and B phases were cracked. The links were also replaced as a preventative maintenance measure. The cracked condition of these operating links had no af fect on .the proper operation of the breaker. Also, the breaker secondary contacts and X relay contacts were cleaned. "A" Reactor TCB was returned to its proper cubicle, racked into place, and tested in accordance with the applicable portions of PT-19A. This test was repeated two additional times to ensure "A" Reactor TCB would respond properly to a trip signal. "A" Reactor TCB was declared operable at 1036 hours0.012 days <br />0.288 hours <br />0.00171 weeks <br />3.94198e-4 months <br /> on December 23, 1982.

At no time was the plant operated in a less conservative condition than allowed by the Technical Specifications, and the installed TCB's were always capable of responding to both automatic and manual trip signals.

An engineering evaluation has been initiated to determine if periodic replacement of the Reactor TCB undervoltage relays is advisable and to review the lubrication and cleaning intervals for adequacy. All cor-rective actions determined to be necessary as a result of the-evaluation will be implemented. Additionally, the Reactor and Bypass TCB's will be inspected during the upcoming Steam Generator Inspection outage with

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particular attention being directed to the condition of the undervoltage relays and trip mechanism operating links.

Should you have any questions regarding this special report, please contact me.

Very truly yo r ,

Ibb ' 6[$f R. B. Starkey, Jr.

General Manager H. B. Robinson SEG Plant HTC:JMC/bss cc: S. P. Weise

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