Headquarters Daily Report FEBRUARY 04, 1997 *************************************************************************** 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 FEB. 04, 1997 Licensee/Facility: Notification: Texas Utilities Electric Co. MR Number: 4-97-0014 Comanche Peak 1 2 Date: 02/04/97 Glen Rose,Texas Resident Inspectors Dockets: 50-445,50-446 PWR/W-4-LP,PWR/W-4-LP Subject: POTENTIAL CONDITION OUTSIDE DESIGN BASIS Reportable Event Number: 31722 Discussion: Comanche Peak reported that they have identified a postulated scenario that may be more limiting than the FSAR accident analysis for a steam generator feedline rupture event. They discovered this after reviewing Event Number 31443 reported at Seabrook. The scenario involves a feedline rupture on Steam Generator 1 of a sufficient size such that all main feedwater flow is delivered to the break coincident with an assumed single failure occurring in the B train of the Solid State Protection System. This would result in the B motor driven AFW pump not receiving a start signal when the faulted steam generator reaches the lo-lo setpoint. The assumed failure would also affect the automatic function of the B train steam supply valve for the turbine driven AFW pump for opening upon receipt of a lo-lo level in 2 or more steam generators after a turbine trip. In this scenario, without any additional action, AFW flow would only be delivered to the faulted steam generator. However, at Comanche Peak, other AFW pump start circuitry, independent of the assumed single failure, would result in providing adequate AFW flow to the non-faulted steam generator. Specifically, upon a trip of both main feedwater pumps, an independent start signal will be generated for start of the motor driven AFW pumps. This signal is independent of the SSPS and is, therefore, not subject to the assumed single failure. Based on a preliminary analysis of this additional start signal along with operator actions to isolate the faulted steam generator, the licensee has determined that all acceptance criteria is satisfied and that the FSAR conclusions continue to be valid for the feedline rupture event. Regional Action: Resident inspectors will review the licensee's actions related to this matter. Contact: J. Tapia (817)860-8243 _