Morning Report for May 27, 1999
Headquarters Daily Report MAY 27, 1999 *************************************************************************** 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 I MAY 27, 1999 Licensee/Facility: Notification: Northeast Utilities MR Number: 1-99-0019 Millstone 2 Date: 05/27/99 Waterford,Connecticut SRI PC Dockets: 50-336 PWR/CE Subject: MANUAL REACTOR TRIP BECAUSE OF A SECONDARY STEAM LEAKS Reportable Event Number: 35763 Discussion: At about 3:12 p.m. on May 25, 1999, operators manually tripped the Unit 2 reactor after experiencing feedwater (FW) system transients and receiving a report of a steam leak in the turbine building. The plant responded to the trip as designed with no complications. Operators isolated the steam supply to the turbine building to ensure the steam leak would be isolated. Upon completion of the operator's standard post-trip actions, Unit 2 was stable in Operational Mode 3, hot standby, at normal operating pressure and temperature. Decay heat removal was provided by the steam generators using auxiliary feedwater and the atmospheric steam dump valves. There were no injuries as a result of the steam leak. The source of the steam leak was the inlet flange on the relief valve on the 1A main FW heater, the first heater downstream of the "A" main FW pump. The relief valve, whose setpoint is 450 psi, is designed to protect the FW heater shell. Due to improperly functioning level control valves in the 1A and 2A heaters, the 1A heater pressure increased and lifted the relief valve. The licensee believes that the resulting force on the relief valve tailpiece imposed sufficient force on the relief valve inlet flange to relieve the gasket pre-load allowing the gasket to be displaced. The licensee plans to remain in Operational Mode 3, hot standby, while correcting the cause of the trip. In addition to completing some minor repairs prior to restart, the licensee plans to test and inspect the level control system for the FW heaters and conduct an inspection of the secondary plant following the transient imposed by the reactor trip. Regional Action: The resident inspectors responded to the control room to observe the post trip activities until the plant was stable in Operational Mode 3. The resident inspectors are also following the licensee's investigation into the cause of the FW system transient. Contact: David Beaulieu (860)447-3170 James Linville (610)337-5129 _
Page Last Reviewed/Updated Wednesday, March 24, 2021
Page Last Reviewed/Updated Wednesday, March 24, 2021