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ACCESSION #: 9510060257 CP&L Carolina Power & Light Company William R. Robinson PO Box 165 Vice President New Hill NC 27562 Harris Nuclear Plant SEP 29 1995 SERIAL: HNP-95-087 United States Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT DOCKET NO. 50-400/LICENSE NO. NPF-63 10 CFR 21 REPORT - CHARGING SAFETY INJECTION PUMP MINIFLOW CHECK VALVE DEFICIENCY Gentlemen: On September 27, 1995, Carolina Power & Light Company (CP&L) determined that deficiencies associated with Charging Safety Injection Pump (CSIP) Miniflow Check Valves at the Harris Nuclear Plant were reportable under 10 CFR 21. CP&L hereby submits the enclosed report describing a deficiency in Anchor Darling supplied 2" check globe valves which resulted in not meeting forward flow requirements through the CSIP miniflow lines and also resulted in excessive valve backseat leakage. Harris is Nuclear Plant LER 95-008 dated September 28, 1995, describes an event where the "B" CSIP was placed in service when it was inoperable because of the inability of it's miniflow check valve to meet forward flow testing requirements. Due to plant conditions at the time (Mode 4) this failure of the check valve did not create a substantial safety hazard. However, the forward flow deficiency could have created a substantial safety hazard under different plant conditions and may also be applicable to other nuclear plants. Questions regarding this submittal may be referred to Mr. T. D. Walt at (919) 362-2711. Sincerely, MGW Enclosure c: Mr. S. D. Ebneter Mr. S. A. Elrod Mr. N. B. Le Mr. F. Bensinger (Anchor Darling Valve) State Road 1134 New Hill NC Tel 919 362-2502 Fax 919 362-2095 ENCLOSURE TO HNP-95-087 CAROLINA POWER & LIGHT COMPANY HARRIS NUCLEAR PLANT FAILURE OF CHARGING SAFETY INJECTION PUMP MINIFLOW CHECK VALVES SEPTEMBER 29, 1995 REPORTABLE UNDER 10 CFR 21 E1-1 ENCLOSURE TO HNP-95-087 SUBJECT: Harris Nuclear Plant, 10 CFR 21 reportable deficiency. Failure of Charging Safety Injection Pump (CSIP) Miniflow Check Valves. ITEM WHICH FAILS TO COMPLY: 2" - 1878 Socket Ends Stainless Steel Piston Check Globe Valve (HNP Valve Nos. 1CS-179 & 1CS-193) SUPPLIED BY: Anchor Darling Valve Company, Williamsport, Pa. 17701. NATURE OF DEFICIENCY: Check valves 1CS-179 and 1CS-193 are in the miniflow lines for the CSIPs Trains A & B respectively. The original valves installed utilized a bonnet-to-body seal weld. During Refueling Outage No. 5 (May 1994) a design change was implemented to replace the original valves with the subject valves which utilize a pressure seal bonnet closure design. This modification was completed to improve accessibility to the valve's internals for ASME Section XI inspection purposes. There were no recorded occurrences of forward flow or backseat failures with the original valves. The design function of these check valves is twofold. First, the valve is designed to provide forward flow through the miniflow line during normal and accident conditions. Miniflow ensures that there is at least 60 GPM through a CSIP even if the pump becomes dead-headed due to high Reactor Coolant System (RCS) pressure conditions. Therefore, these check valves must be capable of passing adequate forward flow to allow the miniflow line to accomplish its safety function. Second, the valve is designed to prevent backflow through the miniflow line to prevent flow diversion from an operating CSIP in the event one of the other CSIPs failed or was not in service. Flow diversion might prevent sufficient flow to the RCS and thereby prevent the CSIP from meeting its safety function. Thus, these check valves must be capable of preventing backflow to accomplish their safety function. These valves have exhibited deficiencies since October 7, 1994. The following is a short description of these deficiencies: On October 7, 1994, Valve 1CS-179 exhibited back leakage (value not recorded) and the valve piston was replaced. E1-2 ENCLOSURE TO HNP-95-087 NATURE OF DEFICIENCY: (continued) On January 13, 1995, Valve 1CS-179 was tested and exhibited 6 GPM back leakage. On January 13, 1995, Valve 1CS-193 was tested and exhibited 3 GPM back leakage. Corrective maintenance found the resilient seat only two thirds the way around the disc. On July 8, 1995, 1CS-193 failed a backseat test due to the valve being stuck open. The disc assembly which consisted of a disc, disc skirt, retaining ring, and resilient (soft) seat was replaced with a single piece disc assembly (without a soft seat) supplied by Anchor Darling. On August 4, 1995, 1CS-193 failed a forward flow test. The cause of these failures appear to be the cocking of the piston towards the valve outlet port. The cocking was apparently caused by the relatively large hydraulic surge which occurs when the CSIP is started. These valves were installed in May 1994. They were ordered using a specification which included the following technical requirements: 4.1.3 "All materials except packing,..., shall be suitable for a minimum of 40 years service." 4.3.2 "The valve design shall be based on the following pressure and temperature. The valve must maintain pressure integrity and operability at these conditions. The valves shall also be capable of operation with the specified differential pressure across the valve disc. Design Pressure: 2735 psig for stainless valves. Design Temperature: 650 degrees F metal-to-metal seat design on piston check. Differential Pressure: 2735 psig for stainless steel valves." 5.8 "The valve parts shall be compatible with the specified environment and shall be of suitable material to withstand the operating conditions specified herein." 7.4.2 "Following the shell hydrostatic test, seat leakage testing shall be performed in accordance with MSS-SP-61, except the hold time shall be 5 minutes minimum. Allowable leakage is 2 cc/hr. per inch of nominal valve size." There are two additional safety-related valves of this type installed in the plant at this time: 1CS-536 Boric Acid Transfer Pump A Discharge Check Valve 1CS-546 Boric Acid Transfer Pump B Discharge Check Valve E1-3 ENCLOSURE TO HNP-95-087 NATURE OF DEFICIENCY: (continued) These two valves operate at approximately 120 psi, while the CSIP check valves operate at 2712 psi. Therefore this application is at significantly lower pressure than the CSIP miniflow application and are not subject to the large hydraulic forces caused by pump start-up. These valves were installed on February 4, 1994 and have undergone surveillance testing with no occurrence of forward flow or backseat failures. The defect in question is not considered applicable to these valves. SAFETY IMPLICATIONS: The substantial safety hazard that could have been created is the failure of these valves to pass sufficient forward flow to protect the CSIP when alternate miniflow is required and to prevent backflow through the miniflow line to prevent flow diversion from an operating CSIP in the event one of the other CSIPs failed or was not in service. DATE PROBLEM WAS CONFIRMED: The need to evaluate this deviation was identified on August 17, 1995. It was evaluated and determined to be reportable on September 27, 1995. PROBLEM REPORTED: On September 29, 1995, the NRC Operations Center was notified of this reportable item under 10 CFR 21. CORRECTIVE ACTION: The valves that experienced failures (1CS-179 and 1CS-193) were replaced by valves of the same design as originally installed. The modification which replaced these valves and the acceptance testing demonstrating full flow was completed on September 25, 1995. The original check valve design is still in use on the third CSIP (C Train). No recorded forward flow or backseat failures have occurred on this valve. No further corrective action is planned. E1-4 *** END OF DOCUMENT ***