ML18093A747

Special Rept 88-2:on 880217,reactor Trip Breaker Exceeded Time Requirement for Opening During Surveillance Testing. Caused by Equipment Problem.Undervoltage Trip Attachment Replaced & Breaker Maintained Per Breaker Maint Procedure

ML18093A747
Person / Time
Site:	Salem
Issue date:	03/16/1988
From:	Zupko J Public Service Enterprise Group
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
88-002, 88-2, NUDOCS 8803230106
Download: ML18093A747 (3)

Text

Public Service Electric and Gas Company P.O. Box E Hancocks Bridge, New Jersey 08038 Salem Generating Station March 16, 1988 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Dear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-75 DOCKET NO. 50-311 UNIT NO. 2 SPECIAL REPORT 88-2 This Special Report addresses the circumstances surrounding the Channel B Reactor Trip breaker functional surveillance failure which occurred on February 17, 1988. This report is being submitted in accordance with the reporting requirements of Technical Specification 6.9.2.

Sinc~rely yours,

~).1L) /).

J. M. i<;'fo', -VJ~ A General Manager-Salem Ope~ations MJP:pc Distribution The Ene:-av PGo;:,,'"

8803230106 880316 95*2189 111M1i2-8~

PDR ADOCK 05000311 S DCD

SPECIAL REPORT NUMBER 88-e .*

PLANT IDENTIFICATION:

Salem Generating Station - Unit 2 Public Service Electric & Gas Company Hancock's Bridge, New Jersey 08038 IDENTIFICATION OF OCCURRENCE:

Reactor Trip Breaker exceeded time requirement for opening during surveillance testing Event Date{s): 02/17/88 Report Date: 03/16/88 This report was initiated by Incident Report No.88-054 CONDITIONS PRIOR TO OCCURRENCE:

Mode 1 Reactor Power 100% Unit Load 1140 MWe DESCRIPTION OF OCCURRENCE:

On February 17, 1988 the Reactor Trip Breaker {RTB) channel "B" Technical Specification Table 4.3-1 Functional Surveillance failed.

The breaker indicated opening time exceeded the 10 cycle requirement. It indicated that the breaker opened in 83 cycles.

As required, Technical Specification Table 3.3-1 Action 1 was entered at 1121 hours0.013 days <br />0.311 hours <br />0.00185 weeks <br />4.265405e-4 months <br /> upon the indicated failure of the breaker .. The breaker was replaced with a calibrated spare and at 1247 hours0.0144 days <br />0.346 hours <br />0.00206 weeks <br />4.744835e-4 months <br />, with succesful completion of a functional test, the Action Statement was exited.

Technical Specification Table 3.3-1 Action 1 states:

"With the number of channels OPERABLE one less than requir-ed by the Minimum Channels OPERABLE requirement, be in HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />; however, one channel may be bypassed for up to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> for surveillance testing per Specification 4.3.1.1 provided the other channel is OPERABLE."

As required by the Technical Specifications, the Nuclear Regulatory Commission was notified at 1157 hours0.0134 days <br />0.321 hours <br />0.00191 weeks <br />4.402385e-4 months <br /> on February 17, 1988.-

APPARENT CAUSE OF OCCURRENCE:

The apparent root cause of this event has been attributed to ari equipment problem.

RTB Channel "B" was being tested as per its Technical Specification functional testing requirements. The Sequence of Events (SOE) computer indicated that the RTB opened in 83 cycles instead of the required 10 cycles. Subsequently the RTB was declared inoperabie.

Investigation of .this concern did not reveal ~ specific problem.

Subsequent retesting of the RTB showed it functioning as required.

Also, the UVTA and breaker forces were similar to the as left data from the previous breaker maintenance.

UNIT 2 SPECIAL REPORT 88~ APPARENT CAUSE OF OCCURRENCE:

• It was noted that *the SOE printout showed the breaker had opened at the precise time the trip signal was removed. This indicates *the computer interrupt, which is normally generated by the trip breaker input to the SOE, malfunctioned. If the computer inte*rrupt did malfunction, it would result in the computer waiting for the next interrupt to occur before polling the SOE inputs for state changes.

The next interrupt was then generated by the removal of the trip signal 83 cycles after the trip signal was generated. It is suspected that at this time the computer polled the inputs and found the breaker tripped then time stamped that trip at 83 cycles instead of when the trip actually occurred. This could not be confirmed since additional testing of the replacement trip breaker in this position and of the P-250 computer showed proper timing on the SOE printout.

ANALYSIS OF OCCURRENCE:

The functional surveillance of the reactor trip breakers ensure they.

will reliably function within the respective time limit.to mitigate transients and accidents as taken credit for in the Updated Final Safety Analysis Report (UFSAR} ~-

During the period when the Channel B breaker was not functioning properly, the redundant Channel A breaker was operable and the Channel B bypass breaker was operable. Therefore, this event did not affect the safety of the general public, however, it is reportable to the Nuclear Regulatory Commission in accordance with Technical Specification 6.9.2.

CORRECTIVE ACTION:

Although a specific equipment problem-could not be identified the following prudent action was completed prior to declaring the trip breaker suitable for service:

The Undervoltage Trip Attachment (UVTA} was replaced and the breaker maintained in accordance with the breaker maintenance procedure; The SOE card, suspected 6f malfunctioning, was checked and reseated; Cable connections and breaker connections between breaker and the SOE computer were checked for damage and tightness, however, no anomalies were identified; and The auxiliary relay will be tested during the next scheduled breaker surveillance. This relay is electrically located between the breaker open contacts and the SOE computer.

M ...~ .* I '

General Manage:/-

Salem Operations MJP:pc SORC Mtg.88-022