Headquarters Daily report JANUARY 23, 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 JANUARY 23, 1995 MR Number: H-95-0015 NRR DAILY REPORT ITEM SIGNIFICANT EVENTS EVENTS ASSESSMENT BRANCH DIVISION OF OPERATING REACTOR SUPPORT Subject: POWER-OPERATED RELIEF VALVES INOPERABLE The NRR/AEOD Events Assessment Panel on January 17, 1995, classified the inoperability of both power-operated relief valves (PORVs) at Haddam Neck as a Significant Event for the Performance Indicator Program. The significant event classification was based on the risk significance of the event. Haddam Neck has two Copes-Vulcan PORVs. Both PORVs failed a surveillance test on February 19, 1994, due to a leak in the diaphragm assembly. During the 1993 refueling outage which had ended in July 1993, the licensee replaced the PORV diaphragms with a new type made of different material and of a changed shape. A lubricant was needed to help install the diaphragms due to the changed shape. The lubricant was believed to have allowed some extrusion of the diaphragm from between the base and the cover and away from the bolt holes. This extrusion caused tears at several diaphragm bolt holes and allowed the bolts to loosen over time. The air leakage was such that the PORVs would operate for a short period of time before depleting the air supply in the emergency air accumulator. The PORVs are designed to remain operable for thirty hours during a design basis accident, and capable of four valve strokes during feed and bleed scenarios. The PORVs may be supplied air to open from either the nonsafety related air compressors or the 107 gallon emergency air accumulator. The nonsafety related air compressors can not be credited during an accident since the air compressors are expected to fail because of the harsh environment created when the PORVs open. Once the PORVs have failed closed due to depletion of the emergency air accumulator, core cooling capability is lost if auxiliary feedwater and main feedwater are not available for steam generator cooling. At this point, even if the emergency core cooling injection systems are available, core damage will occur. The Probabilistic Safety Assessment Branch performed a risk assessment of this event and the conditional core damage probability (CCDP) was estimated to be 6 x 10-4. The feed and bleed failure probability was set equal to 1 for 117 days (one-half of the approximate surveillance period of 234 days between July 1993 and February 1994). The largest contributor to the CCDP is the station blackout initiating event (43 percent). Degradation of the electrical system (i.e., station blackout, loss of offsite power, loss of DC bus A) is the initiator which has the largest probability (69 percent) of leading to core damage due to loss of feed and bleed upon PORV failure. CONTACT: Eric Benner, NRR/DOPS/OECB (301) 415-1171 PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION I JANUARY 23, 1995 Licensee/Facility: Notification: Consolidated Edison Co. Of N.Y. MR Number: 1-95-0007 Indian Point 2 Date: 01/23/95 Buchanan,New York SRI PC Dockets: 50-247 PWR/W-4-LP Subject: FUEL POOL DRAINDOWN Reportable Event Number: N/A Discussion: On January 19, 1995, at approximately 10:00 P.M., Con Edison personnel inadvertently isolated the service air header to the Fuel Handling Building. This resulted in a loss of the air supply to the inflatable seal around the fuel pool gate. As the seal deflated, water leaked around the gate and the spent fuel pool level dropped from its normal level of 94 feet (referenced to mean sea level) down to approximately 91 feet (24 feet above the spent fuel assemblies). The low level alarm (setpoint 93 feet 3 in) was received about 3:00 a.m. on January 20, 1995. Con Edison personnel took prompt actions to restore the air header in the Fuel Handling Building, and pumped the water back into the fuel pool using portable pumps. Water level was restored to normal at 1:55 p.m. January 20. There were no abnormal radiation levels observed as a result of this event. The fuel handling building header was isolated when, as part of the preparations for an upcoming refueling outage job to replace the main condenser, the service air header in the turbine building was being tagged out to be removed and relocated. The isolation was intended to be downstream of the branch connection to the fuel handling building. The plant drawings were consulted and the appropriate valve identified. The tag was placed in the field on the valve with that identification tag. However, Con Edison has determined that the valve was mislabelled. The identification label for the valve downstream of the branch connection was placed on the valve upstream of the branch connection during the mid-1980s (time frame based upon the valve identification label was installed). The fuel pool is designed such that if the water level is drained down to the bottom of the gate, approximately 8 feet of water will remain above the spent fuel assemblies. Regional Action: The resident inspection staff will follow Con Edison corrective actions. Contact: Gordon Hunegs (914)739-9360 Lawrence Doerflein (610)337-5378