ML16215A104

Watts Bar, Unit 2 - Technical Specification (TS) 5.9.8 - Post Accident Monitoring System Report

ML16215A104
Person / Time
Site:	Watts Bar
Issue date:	08/02/2016
From:	Simmons P Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML16215A104 (3)

Text

Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381August 2, 201610 cFR 50 4ATTN: Document Control DeskU.S. Nuclear Regulatory CommissionWashington, D.C . 20555-0001SubjectWatts Bar Nuclear Plant, Unit 2Facility Operating License No. NPF-96NRC Docket No. 50-391Technica! Specification (TS) 5.9.8 - Post Accident Monitoring System(PAMS) ReportThe program requirements for the Watts Bar Nuclear Plant (WBN) Post Accident MonitoringSystem (PAMS) requires a report to be submitted within 14 days when Condition B ofTechnical Specification Limiting Condition for Operation 3.3.3, "Post Accident Monitoring(PAM) lnstrumentation," is entered. On July 22,2016, an evaluation determined that thecontainment isolation valve indication for the Steam Generator Blowdown (SGBD) isolationvalves outside containment have been inoperable for more than 30 days. This specialreport is provided in the Enclosure.There are no new regulatory commitments in this letter. Please direct any questionsconcerning this matter to Gordon Arent, WBN Licensing Director, at (423) 365-2004.Respectfully, /Paul SimmonsSite Vice PresidentWatts Bar Nuclear PlantEnclosurecc: See Pag e 2 U.S. Nuclear Regulatory CommissionPage 2August 2, 2016cc (Enclosure):NRC Regional Administrator - Region l!NRC Senior Resident lnspector - Watts Bar Nuclear PlantNRC Project Manager - Watts Bar Nuclear Plant EnclosureTechnical Specification 5.9.8PAI,IS ReportBackqroundThe Watts Bar Nuclear Plant WBN) Technical Specification (TS) 3.3.3, "Post AccidentMonitoring (PAM) lnstrumentation," specifies the operability requirements for PAMinstrumentation. TS Table 3.3.3-1, Function 1 1, "Containment lsolation Valve Position,"requires two operable indication channels per penetration flow path. On June 29, 2016,the outboard Steam Generator Blowdown (SGBD) isolation valves on WBN Unit 2 weredetermined to have inoperable valve position indication.TS 3.3.3 Limiting Condition for Operation (LCO) Condition A allows a single indicationchannel to be inoperable for 30 days. lf the indication channel is not restored within 30days, LCO Condition B is entered, which requires action in accordance with TS 5,9.8 to betaken immediately. TS 5.9.8 requires a report to be submitted to the Nuclear RegulatoryCommission within 14 days.A review for past operability of the SGBD isolation valve indication completed onJuly 22,2016 determined that, due to Environmental Qualification (EQ) concerns, theindication in question had been inoperable when Unit 2 first entered Mode 3 onMarch 30, 2016.This report outlines the preplanned alternate method of monitoring, the cause ofinoperability, and the plans and schedule for restoring the instrumentation channels of theFunction to OPERABLE status,Preplanned Alternate Method of MonitorinqWith the outboard SGBD isolation valve indication inoperable, operations personnelwilluse blowdown flow indication to validate valve closure in the event of a containmentisolation signal.Gause of lnooerabilitvThe outboard SGBD isolation valves are Target Rock solenoid valves with reed switches tosupport position indication. The design of the insulation around the solenoid valvessubjected the valves and the reed switches to elevated temperatures that invalidated theirEQ test report. The insulation for these valves has been removed, resulting in reducedtemperatures at the reed switches.Actions and Schedule to Restore lnstrumentation Function to Ooerable ConditionReplacement of the outboard SGBD isolation valve indication requires the valve to beclosed and de-energized. Loss of blowdown has an adverse impact on steam generatorchemistry, and should be performed when the unit is not at power. The actions to replacethe SGBD isolation valve reed switches have been scheduled following a power ascensionreactor trip from 30 percent power, which is anticipated to occur in August 2016.