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NOED-00-4-001 - Comanche Peak 1 (TXU Electric)UNITED STATES January 24, 2000 Mr. C. L. Terry
Dear Mr. Terry: By letter dated January 19, 2000, and supplement dated January 20, 2000, you requested that the NRC exercise discretion not to enforce compliance with the actions required in Technical Specification 3.7.3. That letter and its supplement documented information previously discussed with the NRC in telephone conversations on January 19 at 2 p.m. CST and on January 20 at 2 p.m. and 6:30 p.m. CST. You stated that on January 21, 2000, you planned to enter a 4-hour Limiting Condition for Operation (LCO) to repair an air leak on a hydraulic unit associated with a feedwater isolation valve (FIV) and that maintenance activities could take longer than 4 hours. You requested that a Notice of Enforcement Discretion (NOED) be issued pursuant to the NRC's policy regarding exercise of discretion for an operating facility, set out in Section VII.c, of the "General Statement of Policy and Procedures for NRC Enforcement Actions" (Enforcement Policy), NUREG-1600, and be effective for a period not to exceed 24 hours. The hydraulic pump for Valve 1-HV-2136, SG 1-03 FIV (FIV 1-03), was not maintaining its prime due to air inleakage. The hydraulic system is used to hold the valve open during normal operation. The failure of the hydraulic pump would not inhibit the valve from shutting within the required time and operability was therefore not impacted; however, failure of the pump would result in a slow closure of the valve and a resultant plant transient. Repair of the FIV at power required mechanically restraining the valve open and replacing its hydraulic pump. During that time, FIV-03 would not be able to perform its function of feedwater isolation. The primary safety function of the FIVs is to isolate main feedwater flow to the secondary side of the steam generators following a high energy line break. Each feedwater line also contains a feedwater control valve (FCV) that provides backup isolation of main feedwater. The FCVs receive the same redundant isolation signals and have the same closure stroke time design requirements as the FIVs. The feedwater isolation function can also be completed through the automatic tripping of the main feedwater pumps. Your Probabilistic Risk Assessment Group assessed the risk of performing the maintenance at power assuming that the FIV was unavailable to perform its intended function. It was concluded that the incremental increase in risk associated with performing the maintenance at power was not risk-significant. You also referenced several industry studies on averted risk which were relevant to your request and which showed that the risks from remaining at power while repairs were made to FIV 1-03, were considered to be less than those associated with a plant transient to shut down the plant. Compensatory actions taken included verifying that the FCV was capable of performing its intended function, conducting briefings prior to the start of the maintenance activity, and assuring that the on shift operations crew were knowledgeable of the appropriate normal and emergency operating procedures. In addition, no other risk significant activities were allowed which may have affected the Unit 1 activity. The safety basis for granting the NOED was that compliance with the Technical Specification LCO would involve an unnecessary plant transient without a corresponding health and safety benefit. The staff agreed with your determination that approving the request for enforcement discretion would avoid an undesirable pressure and thermal transient which would otherwise occur if compliance with the Technical Specification was forced. In addition, the staff considered that there was no relationship with the discovery that unit specific loads which were on common buses may not have been in conformance with the specific words in Regulatory Guide 1.81, "Shared Emergency Shutdown Electrical Systems for Multi-Unit Power Plants." Ensuring that the relationship between these issues was fully understood was an important factor in approving your request. On the basis of the staff's evaluation of your request, including the compensatory measures described above, the staff concluded that an NOED was warranted because we were clearly satisfied that this action involved minimal or no safety impact and had no adverse radiological impact on public health and safety. Therefore, the NRC staff elected to exercise discretion not to enforce compliance with Technical Specification 3.7.3, "Feedwater Isolation Valves (FIVs) and Associated Bypass Valves," for a period of 24 hours to allow repair of FIV 1-03. This letter documents our telephone conversation on January 20, 2000, at 6:36 p.m. CST, at which time we orally issued this NOED. We understand that you entered the Technical Specification LCO at 9:33 a.m. CST on January 20, 2000, that the condition causing the need for this NOED was corrected by you on January 21, 2000, at 3:22 p.m. CST, and that you exited from Technical Specification 3.7.3 and from this NOED at that time. However, as stated in the Enforcement Policy, action will normally be taken, to the extent that violations were involved, for the root cause that led to the noncompliance for which this NOED was necessary.
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