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 37381 August 2, 2016 10 cFR 50 4 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C . 20555-0001 Subject Watts Bar Nuclear Plant, Unit 2 Facility Operating License No. NPF-96 NRC Docket No. 50-391 Technica!

Specification (TS) 5.9.8 - Post Accident Monitoring System (PAMS) Report The program requirements for the Watts Bar Nuclear Plant (WBN) Post Accident Monitoring System (PAMS) requires a report to be submitted within 14 days when Condition B of Technical Specification Limiting Condition for Operation 3.3.3, "Post Accident Monitoring (PAM) lnstrumentation," is entered. On July 22,2016, an evaluation determined that the containment isolation valve indication for the Steam Generator Blowdown (SGBD) isolation valves outside containment have been inoperable for more than 30 days. This special report is provided in the Enclosure.

There are no new regulatory commitments in this letter. Please direct any questions concerning this matter to Gordon Arent, WBN Licensing Director, at (423) 365-2004.Respectfully, /Paul Simmons Site Vice President Watts Bar Nuclear Plant Enclosure cc: See Pag e 2 U.S. Nuclear Regulatory Commission Page 2 August 2, 2016 cc (Enclosure):

NRC Regional Administrator - Region l!NRC Senior Resident lnspector - Watts Bar Nuclear Plant NRC Project Manager - Watts Bar Nuclear Plant Enclosure Technical Specification 5.9.8 PAI,IS Report Backqround The Watts Bar Nuclear Plant WBN) Technical Specification (TS) 3.3.3, "Post Accident Monitoring (PAM) lnstrumentation," specifies the operability requirements for PAM instrumentation.

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 were determined to have inoperable valve position indication.

TS 3.3.3 Limiting Condition for Operation (LCO) Condition A allows a single indication channel to be inoperable for 30 days. lf the indication channel is not restored within 30 days, LCO Condition B is entered, which requires action in accordance with TS 5,9.8 to be taken immediately.

TS 5.9.8 requires a report to be submitted to the Nuclear Regulatory Commission within 14 days.A review for past operability of the SGBD isolation valve indication completed on July 22,2016 determined that, due to Environmental Qualification (EQ) concerns, the indication in question had been inoperable when Unit 2 first entered Mode 3 on March 30, 2016.This report outlines the preplanned alternate method of monitoring, the cause of inoperability, and the plans and schedule for restoring the instrumentation channels of the Function to OPERABLE status, Preplanned Alternate Method of Monitorinq With the outboard SGBD isolation valve indication inoperable, operations personnelwill use blowdown flow indication to validate valve closure in the event of a containment isolation signal.Gause of lnooerabilitv The outboard SGBD isolation valves are Target Rock solenoid valves with reed switches to support position indication.

The design of the insulation around the solenoid valves subjected the valves and the reed switches to elevated temperatures that invalidated their EQ test report. The insulation for these valves has been removed, resulting in reduced temperatures at the reed switches.Actions and Schedule to Restore lnstrumentation Function to Ooerable Condition Replacement of the outboard SGBD isolation valve indication requires the valve to be closed and de-energized.

Loss of blowdown has an adverse impact on steam generator chemistry, and should be performed when the unit is not at power. The actions to replace the SGBD isolation valve reed switches have been scheduled following a power ascension reactor trip from 30 percent power, which is anticipated to occur in August 2016.