Headquarters Daily Report JULY 05, 1996 *************************************************************************** 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 JULY 5, 1996 Licensee/Facility: Notification: Public Service Electric & Gas Co. MR Number: 1-96-0066 Hope Creek 1 Date: 07/03/96 Hancocks Bridge,New Jersey SRI PC Dockets: 50-354 BWR/GE-4 Subject: REACTOR MANUAL CONTROL SYSTEM FAILURE Discussion: At about 7:30 p.m. on July 1, 1996, the reactor manual control system (RCMS) locked up causing a loss of manual control for the control rods, as well as, a full core display indication for the control rod position indication system, and a loss of alarm function for the scram accumulators. The operators attempted to reset the condition; however, the RMCS then lost power. At the time of the event, Hope Creek was at full power and had operated at power for the previous 99 days. With the RMCS locked up, operators entered two 12-hour shutdown action statements due to the loss of the scram accumulator alarm functions since the applicable surveillance requirements require periodic testing of the accumulator pressure and water level alarms. These alarms are normally indicated on the full core display and were unavailable after the power loss. Local accumulator pressure indication is available outside of the control room, and operators commenced two-hour log readings on the these indications. There is no local indication of water level (leak detection) for the accumulators. With this alarm feature unavailable, the operators could not ensure that accumulator water level was acceptable for the scram function. Consequently, all accumulators were declared inoperable which caused all control rods to be declared inoperable. Both associated action statements required restoring the control rods to operable status or be in hot shutdown within the following 12 hours. TS 3.0.3 did not apply to these circumstances and thus, did not require an accelerated shutdown. The affected power supply was replaced after technicians found a blown fuse. Then, after some tuning, the replaced power supply worked acceptably; however, operators still could not reset the RMCS. Additional troubleshooting identified that the "activity control card #1" in the RMCS was grounded. This card was replaced and the RMCS was successfully reset. At about 5:45 a.m. on July 2, following acceptable post-maintenance testing, the associated TS action statements were cleared. Licensee procedures for implementing a plant shutdown for technical specifications require that the shutdown commence in sufficient time for an orderly shutdown. Normally, this would mean, for a 12-hour action statement, that plant shutdown should commence with about six hours remaining in the allowed outage time (AOT). However, in this case, operators could not proceed with an orderly shutdown since they could not move control rods other than by scram function. Given the rod pattern at the time of the event, reactor engineering expected that, at most, a reduction to about 85 to 90 percent power could be achieved by lowering recirculation flow prior to causing flow- biased flux trips on the average power range monitors. The senior nuclear shift supervisor elected REGION I MORNING REPORT PAGE 2 JULY 5, 1996 MR Number: 1-96-0066 (cont.) to not reduce power at that time since it would result in a number of alarm or off-normal conditions, which he felt could be distracting. He recognized that an orderly shutdown was not possible with the RMCS locked up, and was prepared to manually scram the unit from 90 to 100 percent power if the AOT expired. Conditions were restored prior to AOT expiration. Regional Action: The resident inspectors responded to the event and monitored licensee recovery actions, as well as control room activities. Contact: Larry Nicholson (610)337-5128 Robert Summers (609)935-3850 _ REGION I MORNING REPORT PAGE 2 JULY 5, 1996 Licensee/Facility: Notification: Public Service Electric & Gas Co. MR Number: 1-96-0065 Hope Creek 1 Date: 07/03/96 Hancocks Bridge,New Jersey SRI PC Dockets: 50-354 BWR/GE-4 Subject: SAFETY AUXILIARY COOLING SYSTEM (SACS) CONCERN - HEAT REMOVAL CAPACITY Discussion: As part of continuing engineering review of the ultimate heat sink capacity at the Hope Creek station, the licensee discovered that the actual flow through the SACS system is apparently greater than assumed in the ultimate heat sink calculations. The net effect of this concern is that this reduces the current margin in the ultimate heat sink temperature for certain plant operating configurations. The licensee has limited operation of the plant to river water temperatures below 85.7 degrees F. This administrative limit is still valid (or bounding) as long as both SACS loops are operable. However, plant technical specifications permit cross-tieing the SACS loops for the purpose of providing cooling water flow to the emergency diesel generators provided that one of the SACS loops has become inoperable. Upon this allowed but unusual alignment of SACS, the SACS flow concern could be more limiting than the current administrative limits for service water (ultimate heat sink) temperature. The licensee continues their investigation of this concern and is developing appropriate guidance for the operators as a contingency measure for the potential case of operations with SACS cross-tied. Current plant configuration for both service water and SACS is that all subsystems are operable. The current service water temperature is: 79 degrees F. Regional Action: Routine resident follow-up. Contact: Larry Nicholson (610)337-5128 Robert Summers (609)935-3850 _