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LER 05000336/2013-003-00 (Unit 2) describe … LER 05000336/2013-003-00 (Unit 2) describes an unanalyzed condition in which Dominion identified their DC ammeter circuits were unfused. Specifically, Dominion did not provide overcurrent protection for wiring associated with DC ammeter indication in the control room to prevent wires from overheating due to fire induced faults and excessive currents flowing through the cable. With enough current flowing through the cable, the potential existed that the overloaded ammeter wiring could damage system wiring or adjacent safety-related circuits in the cable raceways needed for post-fire safe shutdown. This condition could result in a loss of the associated safe shutdown components or a secondary fire in another fire area. The failure to protect safe shutdown cables from the effects of postulated fires was a performance deficiency. This performance deficiency was a violation of Millstone Power Station, Unit 2, Renewed Facility Operating License Condition 2.C.(3), which requires in part, post-fire safe shutdown cables remain free of the effects of fire-induced cable faults during postulated fires. Contrary to the above, Dominion identified they failed to meet this requirement and the condition existed since initial construction of Unit 2. The issue was more than minor because it was associated with the protection against external events (fire) attribute of the mitigating systems cornerstone and it adversely affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. The team determined that the finding was of very low safety significance (Green), based IMC 0609, Appendix F, Fire Protection Significance Determination Process (SDP), Phase 2 screening criteria. The finding screened to Green based upon, task number 2.3.5, because the affected cables were routed in alternate shutdown fire areas that are continually manned or protected by detection and automatic suppression systems. Remaining fire areas are protected by detection systems, automatic suppression systems or rely on manual fire-fighting activities. Additionally, the cable construction is Institute of Electrical and Electronics Engineers (IEEE) 383 (thermoset) which decreases the likelihood of inter-cable and intra-cable interactions. Based on a team walkdown, the team determined that the ammeter cable routing was not routed near a credible fire ignition source in the affected fire areas. Because this finding is of very low safety significance and had been entered into Dominions corrective action program (CR530987), this violation is being treated as a Green, licensee-identified NCV consistent with the NRCs Enforcement Policy.nsistent with the NRCs Enforcement Policy.

Discovered date

23:59:59, 30 September 2016 +

Docket

05000336 +

Event date

23:59:59, 30 September 2016 +

Finding integer

2 +

Finding type

Non-cited violation +

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Identified by

Licensee-identified +

Inspection Manual Chapter

NRC Inspection Manual 0609/Appendix F +

Inspection report

IR 05000336/2016007 +

Inspector

Christopher Cahill +, Scott Freeman +, W Cook +, S Galbreath +, K Young +, Dan Orr +, Eugene Dipaolo +, Jigar Patel +, Jeff Rady + and Louis Dumont +

LER

05000336/LER-2013-003, Regarding Postulated DC Ammeter Circuit Hot Shorts +

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15:55:17, 30 May 2018 +

Person