Headquarters Daily Report NOVEMBER 28, 1995 *************************************************************************** REPORT NEGATIVE NO INPUT ATTACHED INPUT RECEIVED RECEIVED HEADQUARTERS û REGION I û REGION II û REGION III û REGION IV û PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION I NOV. 28, 1995 Licensee/Facility: Notification: Public Service Electric & Gas Co. MR Number: 1-95-0143 Hope Creek 1 Date: 11/28/95 Hancocks Bridge,New Jersey Dockets: 50-354 BWR/GE-4 Subject: INADVERTENT EMERGENCY DIESEL GENERATOR BREAKER CLOSURE; GRASS INTRUSION AT SERVICE WATER INTAKE Discussion: On November 26, 1995, with the plant in Mode 5 (Refuel), two events occurred that had a significant impact on Hope Creek station operations: (1) At approximately 12:15 a.m., control room operators were preparing to synchronize and load the "B" emergency diesel generator (EDG) to complete an 18 month technical specification surveillance (24 hour run with "hot" restart). Four previous attempts to perform this surveillance over the past week were unsuccessful because of failed generator bearing temperature instrumentation and faulty measurement and test equipment. During this most recent attempt, when the operator energized the alternate infeed breaker synchroscope to compare line versus bus voltage, the EDG output breaker unexpectedly tried to close 120 degrees out of phase with its associated 4160 VAC vital bus. A loud noise was heard in the control room and the vital switchgear room, and the EDG output breaker tripped free. The EDG continued to run unloaded and power to the vital bus was not interrupted. Following the event, no obvious visual indication of damage to the vital switchgear or the "B" EDG was identified. The licensee initiated a Significant Event Review Team (SERT) to thoroughly examine this event and identify root causes and corrective actions. Preliminary results of this review have determined that a failed Bailey Controls solid state logic module may be at fault; however, the suspect card was removed and bench tested satisfactorily. In addition, a new card was installed in its place and the condition could not be repeated. The SERT also noted that previous problems with this same logic module were documented in March 1995, but no work had been completed prior to this event. Both the "A" and "C" EDG's are operable, satisfying the minimum number of EDG's required for the current operating mode (TS 3.8.1.2). The "D" EDG is not available at this time due to scheduled testing of its associated vital battery bus. (2) At approximately 8:30 p.m., control room operators received indication of a significant grass intrusion at the station's service water intake structure. The traveling water screens at the suction of both operating service water pumps ("A" and "B") had restricted flow, indicated by high differential pressure across the screens and low pump motor current for both pumps. At the time, the "D" pump was out of service for scheduled maintenance. In accordance with abnormal operating procedures, operators attempted to start the "C" service water pump. However, within seconds of its start, the "C" pump tripped on overcurrent. Following the event, the "C" pump motor windings were "meggered" and found to be shorted. Further, operators discovered that the "B" pump discharge strainer (rotating basket) tripped on overload due to a high differential pressure condition caused by grass clogging. REGION I MORNING REPORT PAGE 2 NOV. 28, 1995 MR Number: 1-95-0143 (cont.) Significant amounts of grass were found on the traveling screens which was subsequently removed. The "B" pump strainer element was backwashed and restored to normal, but the pump is not considered operable because of ongoing scheduled maintenance on the "B" and "D" channels of protection instrumentation. The station is currently in a 72 hour action statement (TS 3.7.1.2.b) since only one of the two required service water pumps is operable ("A" pump). The station plans to replace the "C" pump motor with the motor from the "D" pump. Regional Action: The resident inspectors will continue to monitor the status of the licensee's reviews and plans for needed corrective maintenance. Contact: Robert Summers (610)337-5189 Larry Nicholson (610)337-5128 _ REGION IV MORNING REPORT PAGE 2 NOVEMBER 28, 1995 Licensee/Facility: Notification: Wolf Creek Nuclear Oper. Corp. MR Number: 4-95-0151 Wolf Creek 1 Date: 11/28/95 Burlington,Kansas Licensee Phone Call to the SRI Dockets: 50-482 PWR/W-4-LP Subject: LOSS OF APPROXIMATELY 75 ANNUNCIATORS Discussion: On November 27, 1995, at 6:55 p.m. (CST) approximately 50 control room annunciators alarmed in several unrelated groups. After verifying that the alarms were not caused by an event in progress and determining that the alarms were not valid, operators determined that the groups of alarming annunciators also did not correspond to any of the patterns associated with power supply failures in the annunciator system. Operators determined that the 50 illuminated annunciators represented far less than 75 percent of the total number of annunciators in the control room, the fraction that required an entry into the emergency plan. Additional troubleshooting identified that a 125 Volt DC to 125 Volt DC isolation converter failed. This converter provided power to optical isolators in the RK045A annunciator cabinet for approximately 75 annunciators. The optical isolators isolated safety related field input circuits from the nonsafety-related annunciator circuitry. Without power to the optical isolators, approximately 50 of the 75 failed annunciators failed to the alarm state, while the remaining 25 (approximately) annunciators did not fail in an alarm state due to the circuit design. On November 28, 1995, at approximately 2 a.m., electricians replaced the DC to DC isolation converter, restoring the failed annunciators to an operable condition. Regional Action: The SRI responded to the site and monitored licensee activities. Contact: F. Ringwald (316)364-8653 _