\r\n\r\n\r\nPOTENTIAL EXISTENCE OF DEFECTS IN SHIELD PASSIVE THERMAL SHUTDOWN\r\nSEAL SYSTEM\r\n<\/p>\r\n
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<\/a>\r\n“The defect being reported concerns an identified inconsistency\r\nbetween the intended design functionality of the SHIELD passive\r\nthermal shutdown seal (SDS) and that observed during post-service\r\ntesting.\r\n<\/p>\r\n
\r\n“The purpose of the SDS is to reduce current reactor coolant system\r\ninventory losses to very small leakage rates for a plant that\r\nresults in the loss of all reactor coolant pump (RCP) seal cooling.\r\nThe SDS is a thermally actuated, passive device integral to the RCP\r\nNumber 1 seal insert and is positioned between the Number 1 seal and\r\nthe Number 1 seal leak-off line to provide a near leak-tight seal\r\nonce activated.\r\n<\/p>\r\n
\r\n“There are two delivered components associated with this report: 1.\r\nthe SDS hardware, and 2. the Probability Risk Assessment (PRA) SDS\r\nmodel and the assigned SDS reliability. The hardware component is\r\nthe SHIELD passive thermal shutdown seal. The associated PRA SDS\r\nmodel and assigned reliability basic component is WCAP-17100-P-A,\r\nSupplement 1, Rev. 0, ‘PRA Model for the Westinghouse Shut Down Seal\r\nSupplemental Information for All Domestic Reactor Coolant Pump\r\nModels’ (dated December 2012).\r\n<\/p>\r\n
\r\n“The SDS has only been delivered and installed in the following\r\nplants: Beaver Valley Unit 2, Callaway, D.C. Cook Unit 1, Farley\r\nUnits 1 and 2, and Wolf Creek.\r\n<\/p>\r\n
\r\n“Westinghouse has concluded that the hardware itself will not\r\nadversely impact safe plant operation.\r\n<\/p>\r\n
\r\n“Westinghouse has completed a root cause analysis (RCA) and an\r\nindependent third party review of this RCA is expected to be\r\ncompleted by August 2013. In parallel, SDS design improvements are\r\nbeing considered and may be completed during the third quarter of\r\n2013. Additionally, and if necessary, Westinghouse will revise\r\nWCAP-17100 and its Supplements, as needed, to reflect any new\r\ninformation that is developed.\r\n<\/p>\r\n
\r\n“Affected customers have been informed via their respective Customer\r\nProject Managers of the post-service test failure.”\r\n<\/p>\r\n<\/blockquote>\r\n
\r\nIf you’re a Georgia Power customer, you’re a Southern Company\r\ncustomer, and Southern Company owns Farley units 1 and 2.\r\nWere you informed?\r\n<\/p>\r\n
\r\nThere’s a picture in here, but it’s copyrighted by Southern Company,\r\nin Pressurized Water Reactor Owners Group News, Fall 2011,\r\n\r\nU.S. NRC Approves PWROG PRA Model for New Westinghouse RCP Shutdown Seal for Referencing in Licensing Applications<\/a>,\r\n
\r\n\r\nInstallation of the SDS at Farley Unit 2 (see photo) along with\r\nimplementation of the PRA Model took place this October. Scott said\r\nthat Southern Nuclear also has plans to install the SDS at its Alvin\r\nW. Vogtle Electric Generating Plant (Units 1 and 2) near Waynesboro,\r\nGeorgia (USA).\r\n<\/p>\r\n
\r\nPacific Gas and Electric also is scheduled to install the SDS at its\r\nDiablo Canyon Power Plant in San Luis, California (USA) in fall\r\n2012, said Mendez.\r\n<\/p>\r\n
\r\n[Picture redacted due to copyright]\r\n<\/h3>\r\n
\r\nNumber 1 Seal Housing with Westinghouse SDS Insert at Farley Unit 2\r\n
\r\nSouthern Company grants Westinghouse permission to use photographs\r\nof the SHIELD shutdown seal installation at Farley Unit 2, for the\r\nexpress purposes of Westinghouse’s PRA Model article for the PWROG\r\nNews. This photograph is copyrighted by Southern Company.\r\n<\/p>\r\n<\/blockquote>\r\n
\r\nWestinghouse just introduced this seal two years ago,\r\nand first installed it at Farley, according to Westinghouse PR\r\n22 June 2011,\r\n\r\nWestinghouse Introduces SHIELD\u00ae Passive Thermal Shutdown Seal<\/a>,\r\n
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<\/a>\r\n\r\nWestinghouse partnered with Southern Nuclear Operating Company (SNC)\r\nto successfully install the first-of-its-kind SHIELD\u00ae passive\r\nthermal shutdown seal in each RCP at the Joseph M. Farley Nuclear\r\nPower Plant (Unit 1) near Dothan, Alabama (USA), during the plant’s\r\nfall 2010 refueling outage. SNC has announced plans to apply the\r\nproduct to Farley Unit 2 during its next refueling outage.\r\n<\/p>\r\n
\r\nThe Farley Unit 1 SHIELD\u00ae seal installation garnered a 2011 Nuclear\r\nEnergy Institute (NEI) Top Industry Practice (TIP) Award for\r\nSouthern Nuclear. The installation of the SHIELD\u00ae shutdown seal\r\nreduced the estimated risk of core damage by some 40 percent, and\r\nthe overall plant safety margin also has been improved.\r\n<\/p>\r\n<\/blockquote>\r\n
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<\/a>\r\nMore details by Marsha White, Westinghouse Technical Communications,\r\nin Power Engineering 1 September 2011,\r\n\r\nPassive Thermal Shutdown Seal Successfully Installed at Farley Plant<\/a>.\r\n