Headquarters Daily Report SEPTEMBER 28, 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 SEP. 28, 1998 Licensee/Facility: Notification: Generic MR Number: H-98-0141 Bwr Plants Date: 09/28/98 Subject: Potential for Directional Control Valve Electrical Connection to Interfere with Inlet Scram Valve on HCUs Discussion: Recent observations by NRC resident inspectors at three plants identified a potential problem with operation of the limit switch actuator of the inlet scram valve because of interference from the electrical connector and/or cable for the directional control valve on control rod drive hydraulic control units (HCUs). Inspectors at Duane Arnold, Vermont Yankee, and Pilgrim found the existence of this problem at those plants. The solenoid housing containing the solenoid coil and electrical wiring slides over the plunger on the base assembly and is attached to the base assembly by a keeper ring. As a result, the solenoid housing is free to rotate to a position where either the electrical connector or the cable can interfere with the operation of the inlet scram valve. The scram function would not be impacted because the inlet scram valve actuator would be strong enough to overcome the interference. However, the cable or connector on the solenoid housing could be damaged, and in the worst case, result in a short circuit in the rod control system that would prevent normal control rod insertion or withdrawal (although the scram function would not be affected). This issue was addressed by General Electric's Nuclear Energy Division in Service Information Letter (SIL) No. 3, "Control Rod Drive - Hydraulic Control Unit No. 729E950G1-G6," issued on July 31, 1973. The SIL recommended that each HCU be inspected and the solenoids be rotated out of the way of the inlet scram valve. It also stated that the cable could be secured to the HCU frame leg to hold the solenoid housing in the correct position and prevent it from interfering with the inlet scram valve. Some licensees subsequently used nylon cable ties to secure the cables to the HCU frame. Over the years, the message of the SIL may have been forgotten. Because of the tight quarters that plant personnel encounter during performance of maintenance on the HCUs, it is possible that the solenoid housings on adjacent HCUs can be bumped out of position, or cable ties may be removed during maintenance and not replaced at the completion of the maintenance. Contacts: Brian McDermott, Region I (802) 257-4319 E-mail: bjm@nrc.gov Michael Kurth, Region III (319) 851-5111 E-mail: mfk@nrc.gov David Skeen, PECB/DRPM/NRR (301) 415-1174 E-mail: dls@nrc.gov HEADQUARTERS MORNING REPORT PAGE 2 SEP. 28, 1998 MR Number: H-98-0141 (cont.) _ HEADQUARTERS MORNING REPORT PAGE 2 SEPTEMBER 28, 1998 Licensee/Facility: Notification: MR Number: H-98-0142 Proposed Generic Communication Date: 09/28/98 Subject: Proposed NRC Information Notice Concerning Failure of Socket Welds on Letdown Lines Discussion: The NRC intends to issue an Information Notice concerning failure of socket welds on letdown lines. Specifically, the Information Notice will address erosion of orifices and subsequent vibration induced fatigue failures of welds in letdown lines. Contacts: Carol Lauron, EMCB/DE/NRR 301-415-2736 E-Mail: cll@nrc.gov John Tappert, PECB/DRPM/NRR 301-415-1167 E-Mail: jrt@nrc.gov _