Headquarters Daily Report JUNE 24, 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 - HEADQUARTERS JUNE 24, 1998 MR Number: H-98-0097 NRR DAILY REPORT ITEM GENERIC COMMUNICATIONS NRC INFORMATION NOTICE 98-24: STEM BINDING IN TURBINE GOVERNOR VALVES IN REACTOR CORE ISOLATION COOLING (RCIC) AND AUXILIARY FEEDWATER (AFW) SYSTEMS, dated June 26, 1998 The U.S. Nuclear Regulatory Commission is issuing this information notice to inform addressees about a design oversight that prevented operation of a safety-related system. Technical contacts: Vern Hodge, NRR 301-415-1861 E-mail: cvh@nrc.gov John Boardman, AEOD 301-415-6354 E-mail:jrb@nrc.gov _ HEADQUARTERS MORNING REPORT PAGE 2 JUNE 24, 1998 MR Number: H-98-0098 NRR DAILY REPORT ITEM GENERIC COMMUNICATIONS Generic Letter 98-03, "NMSS LICENSEES' AND CERTIFICATE HOLDERS' YEAR 2000 READINESS PROGRAMS," was issued on June 22, 1998. This letter was issued to all uranium hexafluoride production plants, uranium enrichment plants, and uranium fuel fabrication plants to (1) notify them of the need for Year 2000 readiness programs, (2) request that they complete their programs by December 31, 1998 and be Year 2000 compliant by December 31, 1999, and (3) require them to submit a written response indicating whether they will take the requested action. Contacts: Gary Purdy, NMSS/IMNS Harry Felsher, NMSS/FCSS 301-415-7897 301-415-5521 E-mail: gwp1@nrc.gov E-mail: hdf@nrc.gov _ HEADQUARTERS MORNING REPORT PAGE 3 JUNE 24, 1998 Licensee/Facility: Notification: MR Number: H-98-0099 Limerick Generating Station, Unit 2 Date: 06/24/98 Subject: ROOT CAUSE FOR SPURIOUS ACTUATION OF STANDBY LIQUID CONTROL SYS. Discussion: On June 3, 1998, the Limerick Generating Station experienced a spurious actuation of the standby liquid control (SLC) system pump and injected 300 to 350 gallons of sodium pentaborate into the reactor vessel. At the time of the event the plant was in cold shutdown, the alarm light in the control room associated with the circuit continuity for the squib valve was tagged out, and testing of the safety relief valve (SRV) was in progress. The licensee's investigation team attributes the spurious operation of the SLC pump to electromagnetic induction (EMI) in the redundant reactivity control system (RRCS) cables. The EMI was caused when technicians were cycling the "2M" SRV with the hand switch in the auxiliary equipment room. At Limerick, the cables for the SRV switch share a 6 foot run in the same cable tray with the SLC RRCS cables. The SRV cable is 125 volts DC and the RRCS cables are 120 volts AC. Repeated energizing and deenergizing of the SRV cables from the SRV test induced voltage on the RRCS cables. The voltage spike produced in the RRCS cables by EMI lasted long enough to interact with the CMOS components on the RRCS logic card. Thus, the RRCS logic card interpreted the voltage spike as a valid signal for SLC injection. The design at Limerick is somewhat unique in that firing of the squib valve, starting of the SLC pump, and isolation of the RWCU system are all initiated by the same SLC output card. The licensee has installed ferrite EMI suppression beads on selected wiring in the RRCS cabinet to reduced EMI on the affected wiring. Also, this event has been discussed with other NRC project managers for plants, such as Hope Creek and Perry. that have the same SLC system design as Limerick. Contact: Tom Greene, PECB/NRR 415-1175 E-mail: tag@nrc.gov _