Headquarters Daily report JULY 12, 1995 *************************************************************************** REPORT NEGATIVE NO INPUT ATTACHED INPUT RECEIVED RECEIVED HEADQUARTERS X REGION I X REGION II X REGION III X REGION IV X *************************************************************************** PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION I JULY 12, 1995 Licensee/Facility: Notification: New York Power Authority MR Number: 1-95-0090 Indian Point 3 Date: 07/12/95 Buchanan,New York Dockets: 50-286 PWR/W-4-LP Subject: MAIN TURBINE RUNBACK DURING SURVEILLANCE TESTING Reportable Event Number: N/A Discussion: On July 10, 1995, at 4:28 a.m., a main turbine runback from 89 percent to 50 percent power occurred while testing the over power delta temperature (OP delta T) reactor protection circuits. During the test, instrument and control (I&C) technicians identified a failure in the OP delta T channel 1 setpoint generator. OP delta T channel 1 was declared inoperable, and the affected bistables (OP delta T reactor trip and rodstop/turbine runback) were placed in the trip condition. However, the I&C technicians erroneously returned the OP delta T channel 1 bypass switch from defeat to normal. This action satisfied the turbine runback logic (1 out of 4) and initiated the runback. The OP delta T reactor trip logic is 2 out 4, and was not satisfied. During the transient, the reactor coolant system (RCS) reached a maximum average temperature (Tave) of 585 degrees F, and a maximum pressure of 2350 psig. Because the rod control system was in manual as required by the surveillance test, there was no inward rod movement during the runback. This contributed to higher RCS Tave and pressure, and the powered operated relief valves (PORVs) cycled twice. Rod control was subsequently placed in automatic, and the rods inserted. During the runback, the high pressure steam dumps did not open as expected, which also contributed to higher RCS Tave and pressure. Although the steam dumps did not open, secondary side pressure did not increase enough to open the steam generator atmospheric steam dump valves. After the transient, elevated tailpipe temperatures were noted for the pressurizer PORVs and safety valves. The licensee subsequently determined that a PORV and a safety valve were experiencing slight seat leakage. Currently the plant remains at 50 percent reactor power. OP delta T channel 1 was returned to service after replacing and successfully testing a new setpoint generator module. The high pressure steam dump valve control circuitry was repaired and tested satisfactorily. The licensee continues to evaluate PORV and safety relief valve seat leakage. Regional Action: The residents are continuing to follow licensee activities. Contact: Richard Urban (610)337-5271 PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION II JULY 12, 1995 Licensee/Facility: Notification: Tennessee Valley Authority MR Number: 2-95-0059 Browns Ferry 3 Date: 07/12/95 Decatur,Alabama Dockets: 50-296 BWR/GE-4 Subject: BROWNS FERRY UNIT 3 ESF ACTUATION Reportable Event Number: 29045 Discussion: On July 10, 1995, at approximately 1446, an auto start of the Unit 3 Emergency Diesel Generators (EDGs) occurred while performing a wire lift associated with the EDG start logic. Unit 3 is currently defueled. Wire lifts were being performed in accordance with the licensee's work plan to facilitate testing of the accident signal logic system. While lifting a wire the electrician's pliers shorted between two relay contacts. This resulted in the generation of a simulated accident signal and subsequent auto start of the Unit 3 EDGs. The EDGs did not tie onto the shutdown board since normal supply voltage was available. The EDGs were secured and returned to standby readiness. The Unit 1 and 2 EDGs were unaffected by this event. This event was reported to the NRC as an unanticipated ESF actuation. The licensee is still reviewing the starting sequence of the four EDGs. The 3D EDG started first followed by the remaining 3 EDGs approximately 80 seconds later. Event Number 29045 incorrectly stated that 3 of 3 EDGs started. Interviews with personnel involved in the incident indicated that two short circuits had actually occurred. The first occurred while lifting a wire. The electrician stopped the work and attempted to insulate the wire with insulating tape. A short time later he attempted to lift the wire again but another short circuit occurred. The licensee hypothesizes that the first short circuit started the 3D EDG but did not provide a signal sufficient to auto start all four EDGs. The second short circuit started the remaining EDGs. The licensee is continuing to review the incident. Regional Action: The Resident Inspector is performing followup to the event by inspecting the relay cabinet and reviewing the circuit drawings to confirm the cause. Contact: Mark S. Lesser (404)331-0342