Headquarters Daily Report JUNE 11, 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 JUNE 11, 1996 MR Number: H-96-0045 NRR DAILY REPORT ITEM GENERIC COMMUNICATIONS NRC Information Notice 96-36, "Degradation of Cooling Water Systems Due to Icing," dated June 12, 1996. The NRC is issuing this information notice to alert addressees to potential degradation of facility water intake systems (circulating, service, and fire water) due to icing conditions. Technical contacts: John R. Tappert, NRR (301) 415-1167 Bruce Jorgensen, RIII (708) 829-9615 _ REGION IV MORNING REPORT PAGE 2 JUNE 11, 1996 Licensee/Facility: Notification: Pacific Gas & Electric Co. MR Number: 4-96-0057 Diablo Canyon 1 Date: 06/11/96 Avila Beach,California Licensee Phone Call to RIV Dockets: 50-275 PWR/W-4-LP Subject: MANUAL REACTOR TRIP ON LOSS OF BOTH MAIN FEEDWATER PUMPS Reportable Event Number: 30607 Discussion: On June 10, 1996, at 1:06 a.m. (PDT), Diablo Canyon Unit 1 initiated a manual reactor trip following the loss of both main feedwater pumps (MFPs). The plant response following the trip was generally uncomplicated. Earlier in the shift, a channel set failure alarm was received and was associated with the Eagle 21 solid state protection system (Set 2, Rack 8). Troubleshooting revealed that the channel failure was associated with the loop calculation processor (LCP) which performs calculations for protection functions, performs data comparison to setpoint values, and initiates trip signals. After discussions between maintenance and operations personnel, the decision was made to reset the LCP. Resetting the LCP by I&C technicians caused all rack associated "deenergize to trip" bistables to trip and analog outputs (indicators, control inputs, etc.) to go to zero. The licensee's preliminary evaluation indicates that resetting the LCP initiated a condensate system load transient bypass (LTB) signal when the turbine first stage pressure (PT-506) indication went to zero. The LTB signal automatically realigns the condensate system to raise main feedwater pump suction pressure by bypassing the condensate polishers and feedwater heaters and starting the standby condensate and booster pump set. The LTB signal also eliminates condensate rejection and recirculation flow through the gland seal and steam jet air ejector condensers. Upon receipt of the LTB signal, operators reduced power by 50 MWe in order to maintain power at or less than 100 percent due to the lowered feedwater temperatures (reduced feedwater heating and the resultant drop in RCS cold leg temperature). Following the LTB automatic realignment of the condensate system, operators reset the LTB signal and restored the condensate system to the normal alignment. Operators noted a low MFP suction pressure (approximately 150 psig) and initiated a 25 MW per minute power reduction; however, MFP 1-1 tripped apparently on overspeed. Operators then initiated a rapid ramp to 600 MWe and started all three auxiliary feedwater pumps. Approximately 1 minute later, MFP 1-2 tripped during operator feedwater flow adjustments due to high discharge pressure (possibly due to throttling of feedwater flow). On the loss of the second MFP, the operators initiated a manual reactor trip. Following the reactor trip, operators experienced a decreasing condenser vacuum. Normal vacuum was restored and maintained by starting a vacuum REGION IV MORNING REPORT PAGE 3 JUNE 11, 1996 MR Number: 4-96-0057 (cont.) pump. Unit 1 was maintained in Mode 3 and with decay heat being removed by the auxiliary feedwater system and steam bypass to the condenser. After the reactor trip, other equipment problems were noted including a flange leak on the discharge of heater drain tank Pump 2 and a seal leak on condensate booster Pump 1-2. Diesel Generator 1-1 started but did not load onto the bus. This is a known condition which occurs due to the light loading of the bus. The licensee's evaluation of the event determined that personnel had not fully considered the impact that resetting the LCP would have on the condensate system. As immediate corrective actions, the licensee has limited those personnel who can authorize resetting activities on the solid state protection system. The loss of the MFPs was found to be caused by the condensate system's response on restoration of the LTB signal. While restoration from an LTB signal had been done in the simulator in operator training sessions, apparently the simulator may not accurately model the actual plant response. The licensee is reviewing the training and procedural guidance related to restoration from an LTB signal. Secondary system leaks were repaired. At approximately 6:45 a.m. on June 11, 1996, the licensee began withdrawal of shutdown bank control rods to initiate the Unit 1 startup. Regional Action: The senior resident inspector responded to the site following the reactor trip and monitored the licensee's recovery and corrective actions. The Region continues to follow the licensee's investigation of the cause of loss of the main feedwater pumps. Contact: H. Wong (510)975-0296 M. Tschiltz (805)595-2354 _ REGION IV MORNING REPORT PAGE 3 JUNE 11, 1996 Licensee/Facility: Notification: Nebraska Public Power District MR Number: 4-96-0058 Cooper 1 Date: 06/11/96 Brownville,Nebraska Resident Inspector Dockets: 50-298 BWR/GE-4 Subject: PLANT STARTUP Discussion: On June 9, 1996, the licensee began a reactor startup and the reactor was taken critical at 7:45 a.m. At 11:52 a.m. on June 10, the main generator was placed into service ending a planned outage. The licensee entered the outage on June 1, 1996 (Morning Report 4-96-0052), to perform fuel sipping to identify leaking fuel assemblies. The decision to enter the outage was based on the licensee's desire to minimize the radioactive material contamination and personnel radiation exposure consequences which could result from additional plant operation with failed fuel. The Technical Specification iodine limits were not approached. Work performed during the outage included identification and replacement of one leaking fuel bundle, revision of the core reload analysis for the replaced fuel assembly and for inclusion of revised thermal limits in response to a vendor Part 21 report, repair of two small reactor coolant system leaks inside the primary containment (on test connections), modifications to correct fire protection design deficiencies, and repair of two intermediate range neutron monitoring instrumentation channels. During the startup, the licensee reported that a high pressure coolant injection system valve failed during surveillance testing. Also, one of the previously failed channels of the intermediate range neutron monitoring instrumentation failed. Subsequent licensee review determined that the high pressure coolant injection valve was actually operable. Regional Action: The resident inspectors observed portions of the reactor startup and are performing routine inspection followup. Contact: E. E. Collins (817)860-8291 Mary Miller (402)825-3371 _ REGION IV MORNING REPORT PAGE 4 JUNE 11, 1996 Licensee/Facility: Notification: Texas Utilities Electric Co. MR Number: 4-96-0059 Comanche Peak 2 Date: 06/11/96 Glen Rose,Texas Resident Inspectors Dockets: 50-446 PWR/W-4-LP Subject: LOW FLYING AIRPLANE APPROACHES SITE Discussion: On June 9, 1996, at approximately 2:30 p.m. (CDT), licensee security personnel observed a low flying single engine propellar aircraft inside the protected area. The security officer was able to read the numbers on the side of the airplane. The licensee provided this information to the local sheriff's department. With help from the Federal Aviation Administration (FAA), local law enforcement personnel were able to identify the pilot of the airplane. The licensee indicated that Somervell County officials plan to press charges through the FAA. The state of Texas has been informed. Regional Action: Region IV will continue to monitor ongoing investigations by local law enforcement officials and the FAA. Contact: Blaine Murray (817)860-8126 Dennis Schaefer (817)860-8192 _