NL-22-0315, Technical Specification 5.6.6 Post Accident Monitoring Instrumentation Report for Drywell Temperature Indicator Inoperable for Greater than 30 Days

Technical Specification 5.6.6 Post Accident Monitoring Instrumentation Report for Drywell Temperature Indicator Inoperable for Greater than 30 Days

ML22124A308
Person / Time
Site:	Hatch
Issue date:	05/04/2022
From:	Dean E Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-22-0315
Download: ML22124A308 (3)

Text

~ Southern Nuclear E, D. Dean Ill Sile Vice President 11028 Hatch Parkway , orth Bllxlay, OA 31513 Plant Hatch 912.453.5859 tef 912.453.2077 fax May 4, 2022 U.S. Nucleir R.~gul~tory Commls~lon ATTN: Doeum~nt Control Desk Wishlngton, D. C. 20555e0001 Edwin I. H1teh Nuel@~r Pl~f'lt m Unlt 1 T~chnicil Speelfie~tion ~.6.6 ~oit Accident M@nitorifl{;l lflitn.!m@ntition R~p@rt f@r Drvw~ll T~mp~ratura lndlc~tm Inoperable for Gr~at~r than 30 D~ws Ladiis ~nd G~ntl@m@n:

In ~ceordime~ with Edwin I. H~teh Nucl~~r Plint Unit 1 T~ehnic~l Sp~clfications Llml"t!ng e

Cgnditlon for Operii!tlon 3.3.3.1, Reguird Action B.1, Southfglm Nucl~~r Operatln{;l Compiny (SNC) I~ ~ubmittlng thl~ report r~liited to po~t ~eeldent monitoring lnstrum@ntg1tion, This l~tter eont~ins no r~9,.!l~tory eommitm~n~. If you h~ve any qu@stion~, pl~1s@ ~nt1et Jimmy Collins g1-t 912.4@3.2342.

Resp~et-fully submltt~d,

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E. D. D~~fl Site Vi~~ President. Pl~nt H~teh EDD/jmh Ce: R.~9long1! Adminlitr~tor, R.~sion ll NRR Prnjeet Mimg1g~r = H~teh Senior Re§ident lnsp~ctor = Hatch RTVPE: CHA02.004

NL-22-0315 Edwin I. Hatch Nuclear Plant - Unit 1 Technical Specification 5.6.6 Post Accident Monitoring Instrumentation Report for Drywell Temperature Indicator Inoperable for Greater than 30 Days Enclosure Post Accident Monitoring Instrumentation Report

Enclosure to NL-22-0315 Post Accident Monitoring Instrumentation Report In accordance with Edwin I. Hatch Nuclear Plant (HNP) Unit 1 Technical Specification (TS) 5.6.6 a report is required to be submitted within 14 days upon entering LCO 3.3.3.1 Condition B. TS 5.6.6 states that the report shall outline the preplanned alternate method of monitoring, the cause of the inoperability, and the plans and schedule for restoring the channel to operable status.

Description of Condition On March 30, 2022, while conducting operator rounds, it was noticed a local Drywell Temperature Element (TE), 1T47N003, was reading outside the acceptance criteria.

Subsequently, the related channel was declared inoperable and Condition A of LCO 3.3.3.1, "Post Accident Monitoring Instrumentation" was entered. The Completion Time (CT) of Condition A is 30 days and expired on April 29, 2022. HNP has been unable to return the channel to operable status prior to the Condition A CT and is thus now in LCO Condition B which requires submittal of this report in accordance with TS 5.6.6 within 14 days.

Preplanned Alternate Method of Monitoring There are thirteen TE's in the drywall used to monitor individual temperatures at various levels along with the drywall bulk average temperature. With TE 1T47N003 inoperable, there remain twelve operable TE's that will continue to be monitored, including one, 1T47N009, on the same elevation as 1T47N003. These other TE's are indicating normal, historical temperatures. These TE's are monitored on operator rounds and automatically by recorders in the control room.

Drywall temperatures can be reliably monitored by the other twelve drywell TE's even with 1T47N003 inoperable. Appropriate actions are procedurally captured and will be taken if an increase is noted on any TE.

Cause of lnoperability During operator rounds, TE 1T47N003 was found to be trending up approximately 1-1.5°F per day and eventually failed upscale. All other drywall temperature indications remained stable, including TE 1T47N009 which is on the same elevation as TE 1T47N003. Engineering and l&C performed troubleshooting activities to investigate the cause and to ensure there was not an actual drywall temperature rise. Historical temperature trend data shows that TE 1T47N003 and 1T47N009 have historically tracked each other within an 8-10 degree difference in temperature until TE 1T47N003 recently began to deviate from TE 1T47N009. Additionally, drywall wide range radiation monitor recorder data was reviewed to identify if there were any increases in radiation correlated with the perceived increase in temperature which would be indicative of a steam leak. These trends were found to be within normal bands. Considering the above information, it has been determined that the temperature trend seen on TE 1T47N003 only, and not on any other drywall TEs, would not be indicative of a genuine rise in drywell temperature but rather a failed individual TE. Based on this, TE 1T47N003 has failed and is inaccurate.

Plans and Schedule for Restoring the Instrument to Operable TE 1T47N003 is located in the drywell which cannot be accessed while at power. Therefore, TE 1T47N003 cannot be repaired until entry into the drywall can be made. Repair activities will be completed during the H1R31 refueling outage (February 2024). If, however, Unit 1 were to be shut down due to a forced outage prior to H1 R31, this work is in the required work scope. This work will replace or repair TE 1T47N003 and will restore normal drywall temperature monitoring to operable status.

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