Headquarters Daily Report MAY 24, 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 MAY 24, 1996 Licensee/Facility: Notification: Consolidated Edison Co. Of N.Y. MR Number: 1-96-0051 Indian Point 2 Date: 05/24/96 Buchanan,New York SRI PC Dockets: 50-247 PWR/W-4-LP Subject: REACTOR SCRAM OF MAY 23, 1996 Discussion: At 2:30 a.m. on May 23, 1996, the Indian Point Unit 2 reactor automatically scrammed from 100 percent power. The reactor scram was generated by a single loop loss of flow signal from the reactor coolant system (RCS) loop associated with the 22 reactor coolant pump (RCP). Just prior to this event, maintenance personnel had replaced the breaker for the 24 circulating water pump (CWP) with a spare breaker. The 24 CWP is powered off of 6900 volt (6.9 kv) bus 4, one of six 6.9 kv buses. Unknown to the maintenance personnel, they had installed an incorrectly sized breaker in the cubicle for 24 CWP which resulted in a size mismatch between the breaker's collets and the bus stabs. When the 24 CWP was started, this mismatch caused a high current condition in the breaker which generated a fault on bus 4 and physically damaged the breaker and its cubicle. Due to the fault condition, bus 4 deenergized and caused RCP 22 to lose power which generated the automatic scram on single loop loss of flow. Following the scram, the turbine generator tripped at which time 6.9 kv buses 2, 3 ,4 and 5 (normally powered from on-site power) should have automatically transferred to the off-site power source. Buses 2 and 5 transferred; bus 4 could not due its faulted condition. Bus 3 is designed to transfer together with bus 4, but with the fault on bus 4, bus 3 did not transfer and became deenergized. Loss of bus 3 resulted in the deenergization of the 23 RCP and 480 volt vital bus 3A. Loss of voltage on bus 3A caused all three emergency diesel generators (EDGs) to start as designed; however, as a station blackout condition did not exist, the EDGs did not load (as designed) onto their associated 480 volt vital buses. Operators determined that bus 3A was not faulted and then manually loaded the 3A bus onto the 22 EDG. Plant conditions were stabilized shortly after the scram using the plant's emergency operating procedures. All systems responded as designed to the scram. On the afternoon of May 23, 6.9 kv bus 3 was returned to service and the 23 RCP restarted. Bus 3A was then reenergized from bus 3 and the 22 EDG secured. Regional Action: The resident staff is following Con Edison's resolution of this problem. Root cause investigation is being performed to determine how the wrong sized breaker was placed in the 24 CWP cubicle. Following repair and testing of bus 4, Con Edison plans to reenergize bus 4, restart RCP 22, and then perform control rod drop time testing to collect data in response to NRC Bulletin 96-01. Contact: Curtis Cowgill (610)337-5233 Robert Temps (610)337-5356 _ REGION III MORNING REPORT PAGE 2 MAY 24, 1996 Licensee/Facility: Notification: Northern States Power Co. MR Number: 3-96-0057 Monticello 1 Date: 05/24/96 Monticello,Minnesota FOR INFORMATION ONLY Dockets: 50-263 BWR/GE-3 Subject: UNIT STARTUP AFTER 39 DAY REFUELING OUTAGE AND SHUTDOWN FOR FORCED OUTAGE. Discussion: On May 19, 1996, the licensee initiated a unit startup from a refueling outage which began on April 10, 1996. At about 2:20 p.m. (CST) the unit was made critical. On May 23, the licensee synchronized the generator to the grid. However, about 11 minutes later, operators reduced electrical load and took the generator off-line due to high vibrations on turbine bearing #6. The licensee had experienced bearing vibration problems earlier this week. Preliminary investigation showed that the packing clearances between the turbine shaft and the turbine casing shaft seals on both sides of the low pressure turbines are not within specification. At about 3:00 pm (CST), the operators inserted a manual reactor shutdown to facilitate further inspection and repairs. The licensee plans to resume startup activities on May 26, 1996. During the 39-day outage, the licensee replaced the two low pressure and one high pressure turbines to support a future power uprate project. The licensee expects to achieve increased electrical power output through greater efficiency without increasing thermal power. The licensee also replaced the recirculation pump seals, inspected the core shroud and core spray piping welds, inspected the emergency core cooling system torus suction strainers, and performed other preventive and corrective maintenance activities. During the force outage, the licensee plans to correct the packing clearance problem and repair packing leaks on two steam jet air ejector drain valves. Regional Action: The inspectors observed numerous outage-related and startup activities. The inspectors also observed the manual reactor shutdown activities. Contact: M. JORDAN (708)829-9637 _