Headquarters Daily report MAY 05, 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 MAY 5, 1995 MR Number: H-95-0098 NRR DAILY REPORT ITEM SIGNIFICANT EVENTS EVENTS ASSESSMENT BRANCH DIVISION OF OPERATING REACTOR SUPPORT Subject: UPDATE - POTENTIAL PRESSURE LOCKING OF CONTAINMENT SUMP RECIRCULATION VALVES CLASSIFIED AS A SIGNIFICANT EVENT UPDATE TO MORNING REPORT H-95-0094 DATED APRIL 20, 1995 The NRR/AEOD/RES Events Assessment Panel previously classified the potential pressure locking of both containment sump recirculation valves at Millstone, Unit 2, as a Significant Event for the Performance Indicator Program (see Director's Highlights dated April 19, 1995, and Morning Report H-95-0094). The significant event classification was based on the risk significance of the event because of the emergency core cooling system (ECCS) recirculation function being inoperable. Subsequently, the licensee had quarter-scale testing performed on a smaller valve of the same type and vendor. The testing indicated that a small volume of air is typically trapped in the bonnet, therefore, during a design-basis loss-of-coolant accident (LOCA), the air space in the valve bonnet would act as a cushion and limit the pressure increase in the valve bonnet to about 11 psi. The licensee asserted that these particular valves are operable under these particular conditions. With these valves operable, the ECCS recirculation function remains operable, reducing the risk significance of the postulated event significantly. On May 2, 1995, the NRR/AEOD/RES Events Assessment Panel re-examined this event and determined that it remained a significant event based on weaknesses in the licensee's motor operated valve (MOV) program. The licensee had several prior opportunities to identify the susceptibility of these valves to pressure locking. These prior opportunities include: a Stone and Webster Engineering Corporation (SWEC) review of pressure locking performed in 1990 which did not consider post-LOCA conditions for this valve; Information Notice 92-26 which informed licensees of pressure locking of flexible-wedge gate valves; a Millstone Unit 1 MOV inspection performed in March 1994 which questioned the screening criteria used in the 1990 SWEC review. The most recent opportunity to identify the susceptibility of these valves to pressure locking was a Raytheon Engineers & Constructors independent re-review of the SWEC review which identified these valves as susceptible to pressure locking in September 1994, and for which the licensee did not evaluate the operability of the valves or reportability of the issue until January 1995, after the unit was shut down for a refueling outage. CONTACT: Eric J. Benner (301) 415-1171 PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION III MAY 5, 1995 Licensee/Facility: Notification: Commonwealth Edison Co. MR Number: 3-95-0082 La Salle 2 Date: 05/04/95 Marseilles,Illinois PLANT MANAGER BRIEFING Dockets: 50-374 BWR/GE-5 Subject: DELAY IN RESTART FROM REFUELING OUTAGE TO RETRAIN OPERATING CREWS Reportable Event Number: N/A Discussion: On 5/4/95, the plant manager informed the SRI that as a consequence of the human performance error events on 5/3/95 (see morning report 3-95-0081), all of the operating crews would receive additional classroom and simulator training on management expectations, and changes would be made to the control room crew structure and operator responsibilities. The training for each crew was planned to take eight hours and would include classroom, simulator training, and assessment. Reactor startup is not intended to begin until five of the six crews had completed training, which would be at 4 p.m. Friday 5/12/95. The previous critical path work would have permitted restart on Wednesday 5/10/95. Plant management has made crew training a critical path item to emphasize their intention to reduce human errors and improve operating crew performance. Regional Action: Based on the previous events, the region and resident personnel plan to provide augmented coverage of the Unit 2 restart activities, when they occur. Contact: L. MILLER (708)829-9629 PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION IV MAY 5, 1995 Licensee/Facility: Notification: Nebraska Public Power District MR Number: 4-95-0059 Cooper 1 Date: 05/05/95 Brownville,Nebraska Phone call from Resident Inspector Dockets: 50-298 BWR/GE-4 Subject: REACTOR VESSEL WATER LEVEL PERTURBATION Reportable Event Number: N/A Discussion: On May 1, 1995, with the unit operating at 100%, control room operators had noticed that the reactor vessel water level chart recorder had exhibited larger than normal variance (plus or minus) in steady state level indication. To reduce the variance, an operator slid the level recorder out, turned off the power to the recorder, cleaned the slide wire, and then returned the recorder to service. When the recorder was returned to service, a momentary voltage fluctuation was introduced into the circuitry, which generated a false low water level signal. The reactor feedwater controller responded to the low water level indication and increased output to increase level. The momentary increase in level lasted less than (one) 1 minute, with a resultant level increase of approximately 2.5 inches. The influx of cooler water caused a 25 MWth power increase that lasted for the same duration as the level increase. The licensee's initial investigation into the concern revealed no anomalies, with a preliminary determination of a faulty capacitor in the recorder part of the circuit. Reactor vessel level returned to normal steady state in less than 2 minutes with no further fluctuations. The licensee is continuing to investigate the problem. The licensee has identified two other chart recorders, steam flow and feed flow, that could exhibit the same characteristics upon failure of a similar capacitor. Regional Action: The resident inspectors will perform routine followup to ensure the root cause of the anamoly was determined. Contact: P. Harrell (817)860-8250 T. Reis (817)860-8185 PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION IV MAY 5, 1995 Licensee/Facility: Notification: Texas Utilities Electric Co. MR Number: 4-95-0060 Comanche Peak 2 Date: 05/05/95 Glen Rose,Texas Call from Senior Resident Inspector Dockets: 50-446 PWR/W-4-LP Subject: COMANCHE PEAK UNIT 2 UNPLANNED OUTAGE Reportable Event Number: N/A Discussion: On Saturday, May 6, 1995, the licensee will begin power reduction for an unplanned shutdown of Unit 2 to repair a suspected leaking valve in the chemical and volume control system (CVCS). The small 2-5 gph leak is located inside the reactor coolant system (RCS) loop Room 4 with the leakage originating in the vicinity of two Check Valves (2-8378 A&B) in the CVCS to Loop 4 cold leg charging flow path. Valves 2-8378 A&B are Westinghouse bolted bonnet 3-inch check valves. The licensee believes that the leakage is emanating from the gasketed bonnet joint on one of the check valves. Both valves were disassembled during the previous refueling outage. The licensee is voluntarily taking this short outage to improve plant reliability for the peak demand during the summer months. Work planned for the outage includes seal welding all four 3-inch bolted bonnet check valves in the charging flow path, replacement of packing on leaking Valve 2-8146 (CVCS Loop 4 cold leg charging flow path isolation) potential replacement of a source range nuclear instrument detector, and various repairs of balance of plant equipment. The outage is scheduled to last approximately one week. Regional Action: The resident inspector and Region IV will monitor licensee activities. Contact: A. T. Gody, Jr. (817)897-1500