Headquarters Daily Report APRIL 23, 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 - HEADQUARTERS APRIL 23, 1996 MR Number: H-96-0033 NRR DAILY REPORT ITEM GENERIC COMMUNICATIONS NRC Information Notice 96-24, "Preconditioning of Molded-Case Circuit Breakers Before Surveillance Testing" dated April 25, 1996. The NRC is issuing this information notice to alert addressees to the detrimental effect that preconditioning of molded-case circuit breakers could have on the diagnostic validity of surveillance tests. Technical contacts: Sikhindra Mitra, NRR (301) 415-2783 Stephen D. Alexander, NRR (301) 415-2995 Christopher Myers, RIV (817) 860-8144 _ REGION I MORNING REPORT PAGE 2 APRIL 23, 1996 Licensee/Facility: Notification: Northeast Utilities MR Number: 1-96-0038 Millstone 2 Date: 04/22/96 Waterford,Connecticut RI PC Dockets: 50-336 PWR/CE Subject: EMERGENCY DIESEL GENERATOR FAILURE Discussion: During a routine monthly surveillance on April 17, 1996, the "B" Emergency Diesel Generator (EDG) tripped on high crankcase pressure 5 minutes after being loaded. The plant was shutdown in Mode 5 at the time. The "A" EDG had successfully completed its monthly surveillance several hours earlier. The Unit 2 reserve station supply transformer (RSST) was supplying shutdown electrical loads, and the Unit 1 RSST was available for cross-tie, if necessary. The cause of the diesel failure has not yet been determined. The diesel engine is a 12 cylinder, Fairbanks-Morse (now Colt), opposed piston design. Licensee inspection of the diesel upper internals revealed two melted aluminum bearings, a damaged piston, and apparent damage to the connecting rod or upper crankshaft. An event review team was appointed on April 18, but substantive review was delayed until April 21, when the vendor representative arrived onsite. Maintenance on the "B" EDG, which was performed in March 1996 during the current outage, included an 18-month inspection and preventive maintenance, as well as, replacement of the bearings that subsequently melted. Post-maintenance testing included a 12-hour run-in operation, and a 24-hour load test. The "A" EDG received the same maintenance and testing during this outage with the exception that the bearings were not replaced. Pending a causal analysis by the licensee's event review team, the licensee is considering the "A" EDG fully operable; but is evaluating measures to enhance the availability of redundant power sources while the "B" EDG undergoes extensive repairs. Regional Action: The resident inspectors are following the event review team, as well as operations control of redundant power sources. Some indication of lack of aggressive maintenance of redundancy was evident in licensee plans to conduct maintenance on the Unit 1 RSST subsequent to the "B" EDG failure, and delays in establishing power backfeed through the Unit 2 normal station supply transformer. Region I inspectors will monitor the progress and results of the licensee's causal analysis and corrective actions. Contact: Jacque Durr (610)337-5224 Paul Swetland (203)447-3179 _ REGION II MORNING REPORT PAGE 3 APRIL 23, 1996 Licensee/Facility: Notification: Virginia Power Co. MR Number: 2-96-0033 North Anna 1 2 Date: 04/23/96 Richmond,Virginia Dockets: 50-338,50-339 PWR/W-3-LP,PWR/W-3-LP Subject: NORTH ANNA STATION MANAGEMENT CHANGES Discussion: Virginia Electric and Power Company announced that Mr. E. S. Grecheck, Manager Design Engineering and Support, will replace Mr. W. R. Matthews as the Assistant Station Manager - Operations and Maintenance at the North Anna Station. Mr. Matthews had previously been selected to fill the Station Manager position after Mr. J. A. Stall resigned to take a position at another utility. These changes are effective on May 1, 1996. Regional Action: Information Only. Contact: L. GARNER (404)331-5536 _ REGION II MORNING REPORT PAGE 4 APRIL 23, 1996 Licensee/Facility: Notification: Tennessee Valley Authority MR Number: 2-96-0034 Browns Ferry 3 Date: 04/23/96 Decatur,Alabama Dockets: 50-296 BWR/GE-4 Subject: BROWNS FERRY UNIT 3 SCRAM ON LOW REACTOR WATER LEVEL Discussion: At 3:51 a.m., CDT, on April 21, 1996, Browns Ferry Unit 3 scrammed from 85 percent due to low reactor water level. The low water level was caused by decreased oil pressure in the "3C" reactor feedwater pump turbine (RFWPT) and failure of the "3C" feedwater pump discharge check valve to fully seat. Upon initial indications of the problem, power was reduced from 100 percent. The feedwater pump turbine low oil pressure was due to an incorrectly positioned valve. Operators had just shifted purification lineup from main turbine oil tank to the "3C" RFWPT tank, and oil level was reduced in the RFWPT tank. The disc pin failed on the "3C" feedwater pump discharge check valve. The disc separated from the rest of the valve and only partially blocked reverse flow from the other two feedwater pumps. A packing failure also occurred on the check valve at the actuator pivot arm penetration. Minimum reactor water level during the incident was -47 inches. HPCI and RCIC both actuated and injected to recover reactor level. Other isolation functions actuated as expected. Review of rod scram data indicated that scram times were all within limits. Subsequent to the scram a leak was identified on a flanged connection on the "3A" Reactor Water Cleanup (RWCU) regenerative heat exchanger, and RWCU was isolated. The leak was from the "A" regenerative heat exchanger and was estimated to be 10 gpm. Licensee drawings depict this joint as a gasketed connection which has a seal repair clamp device permanently installed due to chronic leakage. This modification is isolable from the reactor. Isolation is concurrent with RWCU isolation. A revision to the modification was made to permit injection of sealant via the bolting ring instead of just ports in the installed clamp. The RWCU heat exchanger room and most of the "C" feedwater pump room were contaminated as a result of the leaks. The contamination did not hinder personnel in the performance of normal duties. Regional Action: The senior resident responded to the site. The inspector verified the reactor plant was stable, observed control room recorder traces of the incident, discussed the transient with some of the involved operators, and verified that plant management was pursuing the noted areas of concern. The inspectors reviewed the work order with focus on proper control of application of sealant. The inspector observed disassembly of the check valve and attended licensee PORC meetings. The inspectors are continuing review of the RWCU modification. Contact: Mark S. Lesser (404)331-0342 _