Headquarters Daily Report DECEMBER 08, 1998 *************************************************************************** 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 IV DEC. 08, 1998 Licensee/Facility: Notification: Entergy Operations, Inc. MR Number: 4-98-0064 Grand Gulf 1 Date: 12/03/98 Port Gibson,Mississippi Resident Inspectors Dockets: 50-416 BWR/GE-6 Subject: REACTOR CORE ISOLATION COOLING TURBINE OVERSPEED AND TRIP DURING POSTMAINTENANCE TEST Discussion: On December 2, 1998, the licensee removed the reactor core isolation cooling (RCIC) system from service to conduct planned maintenance and modification on the RCIC turbine and pump. The modification included installing oil sample lines at the turbine bearing locations, an activity which required that all of the lubricating/control oil for the turbine be drained. When the turbine steam emission valve was opened during the postmaintenance test of the RCIC system (approximately 4:20 a.m. on December 3, 1998), the turbine reached an overspeed condition. It did not automatically trip and could not be tripped remotely. Operators took immediate action and shut down the RCIC turbine by closing the trip throttle valve from the control room. The licensee quarantined the RCIC turbine until an inspection was completed and formed a significant event review team to perform an investigation into the problems exhibited during the postmaintenance test. Initial investigation of the RCIC turbine/pump revealed that there was damage to the turbine bearings and that the oil in the pump bearing was bad. The licensee identified trapped air in the lubricating/control oil system and this air is believed to be the cause for the lack of control of the turbine and the subsequent turbine overspeed. The turbine was rotated by hand to remove the trapped air and the licensee was able to add 3 more gallons of oil. Initially, the licensee had refilled the system with 7 gallons of oil, per a maintenance procedure. However, the fact that the seals to the turbine had been compromised and more than normal oil leakage had occurred was not recognized. The investigation into the turbine trip function failure has not identified any apparent cause. No damage or problems could be found during the inspection of the electrical and mechanical overspeed devices and the linkage to the trip/throttle valve of the RCIC turbine. Subsequent testing of the overspeed trips and the trip/throttle valve were performed satisfactory. The licensee is continuing their investigation. The repairs to the RCIC system have been completed and testing is in progress. They are also performing an engineering evaluation into the potential overpressurization of the discharge piping of the RCIC pump, which may have occurred during the overspeed condition. REGION IV MORNING REPORT PAGE 2 DEC. 08, 1998 MR Number: 4-98-0064 (cont.) Regional Action: The resident inspectors are observing and reviewing the results of the licensees' investigation. Contact: Joseph I. Tapia (817)860-8243 Ronald A. Kopriva (817)860-8104 _