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Morning Report for Macrh 14, 2000
Headquarters Daily Report MARCH 14, 2000 *************************************************************************** REPORT NEGATIVE NO INPUT ATTACHED INPUT RECEIVED RECEIVED HEADQUARTERS X REGION I X REGION II X REGION III X REGION IV X PRIORITY ATTENTION REQUIRED MORNING REPORT - HEADQUARTERS MARCH 14, 2000 Licensee/Facility: Notification: Part 21 Database MR Number: H-00-0015 Eaton Cutler-Hammer Date: 03/14/00 Subject: Part 21 - Potential misapplication of zinc chromate plating to circuit breaker parts Discussion: VENDOR: Eaton Cutler-Hammer PT21 FILE NO: 99-50-0 DATE OF DOCUMENT: 11/12/99 ACCESSION NUMBER: ML993240465 SOURCE DOCUMENT: EN 36428 REVIEWER: REXB, D. Skeen Eaton Cutler-Hammer (E-CH) reported a potential for malfunction of Westinghouse Type DS and DSL Class 1E circuit breakers. During breaker reconditioning activities on 13 breakers for South Texas Project, some of which had been previously refurbished by Westinghouse in 1994, E-CH personnel discovered two breakers with hardened metal parts that had been plated with zinc chromate. Plating of metal parts is a common practice to improve the appearance of some parts. However, the plating process can allow hydrogen to be diffused into hardened parts which can cause the parts to become embrittled and cause cracking and breaking, if a heat treatment is not applied to desorb the hydrogen (see NRC Information Notice 96-46, "Zinc Plating of Hardened Metal Parts and Removal of Protective Coatings in Refurbished Circuit Breakers", Accession No. 9608090035). E-CH is now the manufacturer of DS and DSL circuit breakers, since buying the manufacturing facilities for the 600-V circuit breaker product line from Westinghouse in 1994, and has recently begun performing safety-related breaker refurbishments. During disassembly of one breaker, E-CH was removing a Spirol pin (trade name for a rolled metal pin) that secures the levering shaft to the interlock plate, when it broke. The pin appeared to be a gold color, indicative of zinc chromate plating. During disassembly of a second breaker, E-CH found a roller constraining link, which is normally blue-black in color, that was also plated with zinc chromate. Westinghouse Repair and Replacement Services told the NRC that the pin in question holds the levering shaft to the interlock plate and that the pin is not removed when the assembly is plated. Westinghouse believes that plating the pin does not present a safety hazard because they have received no reports of this pin failing in service. Licensees may wish to inspect the Spirol pin and the roller constraining pin for signs of damage and whether these parts have been plated during the next scheduled maintenance interval. See Morning Report H-00-0016 for related information. The NRC will post ensuing reports on this subject on its website at http://www.nrc.gov/NRC/PUBLIC/PART21/2000. Contacts: Dave Skeen, NRR Steve Alexander, NRR Kamal Naidu, NRR HEADQUARTERS MORNING REPORT PAGE 2 MARCH 14, 2000 MR Number: H-00-0015 (cont.) 301-415-1174 301-415-2995 301-415-2980 dls@nrc.gov sda@nrc.gov krn@nrc.gov _ HEADQUARTERS MORNING REPORT PAGE 2 MARCH 14, 2000 Licensee/Facility: Notification: Part 21 Database MR Number: H-00-0016 Eaton Cutler-Hammer Date: 03/14/00 Subject: Part 21 - Potential application of incorrect torque specifications to circuit breaker arc chute mounting bolts Discussion: VENDOR: Eaton Cutler-Hammer PT21 FILE NO: 99-51-0 DATE OF DOCUMENT: 11/12/99 ACCESSION NUMBER: ML993210268 SOURCE DOCUMENT: EN 36429 REVIEWER: REXB, D. Skeen Eaton Cutler-Hammer submitted a 10CFR Part 21 report concerning discrepancies discovered during circuit breaker refurbishment activities (EN #36429, 11/12/99). The original Westinghouse maintenance program manual (MPM) for DS low voltage metal enclosed switchgear, written in 1993, listed the arc chute torque values for DS-206 and DSL-206 breakers as 40-45 inch-pounds, and values for the DS-400, -500, and -600 series breakers as 65-70 inch-pounds. Westinghouse Repair and Replacement Services (RRS) personnel told the NRC that prior to putting together the MPM in 1993, no torque values were given for the arc chutes, but because of customer complaints of cracked arc chutes, Westinghouse decided to list torque values for the arc chutes in the MPM. The reason for the difference in values between the 206 model and the other models is that the design of the arc chute boss on the higher series model breakers is more substantial than the design of the arc chute boss on the 206 model. The Westinghouse values were based on experimental data, i.e. tightening the arc chutes until they cracked and then backing down from that value to provide margin. Westinghouse also stated that the breakers were satisfactorily tested seismically in 1994, using the stated 1993 MPM values. Eaton-Cutler Hammer (E-CH) told NRC that they developed torque values for the DS and DSL breakers when they took over production in 1994. The arc chute torque values listed on the design drawing in 1994 was 20-24 inch-pounds for all DS and DSL breakers. There was no differentiation between the 206 model and higher model numbers. However, E-CH stated that they subsequently discovered a small error in the design drawing value, and the correct torque values are given on the manufacturing instructions (MI) that are used on the factory floor to assemble the breakers. The MI lists the torque value as 24 +/- 2 inch-pounds. E-CH recently revised the design drawing to reflect the correct torque value in October 1999. Westinghouse revised the MPM in March 1999 and the arc chute torque values were lowered to match the design drawing values for the DS-206 breakers. The values for the higher series breakers were also lowered to 40 +/- 5 inch-pounds. Westinghouse stated that the higher series values were lowered to provide additional margin to preclude cracking the arc chutes. In addition to the torque value discrepancies, E-CH also noted that the HEADQUARTERS MORNING REPORT PAGE 3 MARCH 14, 2000 MR Number: H-00-0016 (cont.) o-rings used to hold the arc chute mounting bolt in place when the arc chute is not mounted on the breaker, were damaged on some of the breakers being refurbished. At this time the safety significance appears to be minimal. No failures of circuit breakers in service have been reported because of pieces of the arc chutes or o-rings becoming dislodged and falling into the operating mechanism. Also, it is unclear when the arc chutes were cracked, or what torque value was used on the bolts of the cracked arc chutes. It is possible that using the values in the Westinghouse MPM could lead to arc chute cracking, but it is also possible that plant personnel could overtorque the bolts if care is not taken to ensure that the bolts are not overtightened during maintenance activities. Licensees may wish to consider checking the torque value on the arc chute bolts, checking the arc chutes for cracks, and inspecting the o-rings for damage during the next scheduled breaker maintenance interval. See Morning Report H-00-0015 for related information. The NRC will post ensuing reports on this subject on its website at http://www.nrc.gov/NRC/PUBLIC/PART21/2000. Contacts: Dave Skeen, NRR Steve Alexander, NRR Kamal Naidu, NRR 301-415-1174 301-415-2995 301-415-2980 dls@nrc.gov sda@nrc.gov krn@nrc.gov _ REGION II MORNING REPORT PAGE 3 MARCH 14, 2000 Licensee/Facility: Notification: Tennessee Valley Authority MR Number: 2-00-0009 Sequoyah 1 Date: 03/14/00 Soddy-Daisy,Tennessee Dockets: 50-327 PWR/W-4-LP Subject: SEQUOYAH UNIT 1 UNEXPECTED OPERATION OF RESIDUAL HEAT REMOVAL RELIEF VALVE Reportable Event Number: 36792 Discussion: On March 17, 2000, at 0017 Unit 1 was in Mode 5 (cold shutdown), with the reactor coolant system (RCS) temperature at 156 degrees F and 330 psig. Operators were conducting a venting procedure on the residual heat removal (RHR) system to remove any gas voids from the injection path, in preparation for entering Mode 4 (hot shutdown). During this evolution, the licensee believes that the Train A RHR discharge relief valve unexpectedly lifted and released RCS water to the pressurizer relief tank (PRT). The relief valve reseated and RHR A train was isolated with the transient lasting approximately 30 minutes. The PRT rupture disc was breached and approximately 1500 gallons of water was released to the containment. RCS temperature and pressure after the event were 156 degrees F and 145 psig. The RCS release was contained in lower containment and there were no personnel contaminations. The licensee is evaluating the cause of the event and is in the process of replacing the PRT rupture disc and relief valve, and plans to lift-test the replaced valve. Regional Action: The resident inspectors have been following the licensee's troubleshooting activities and corrective actions. Contact: P. E. FREDRICKSON (404)562-4530 _
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