NG-19-0077, Technical Specification 5.6.6 Post Accident Monitoring (PAM) Report
| ML19161A138 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 06/06/2019 |
| From: | Dean Curtland NextEra Energy Duane Arnold |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NG-19-0077 | |
| Download: ML19161A138 (5) | |
Text
June 6, 2019 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001 Duane Arnold Energy Center Docket 50-331 Renewed Op. License No. DPR-49 NEXTeraM ENERGXe
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DUANE ARNOLD NG-19-0077 Technical Specification 5.6.6 Post Accident Monitoring (PAM) Report The purpose of this letter is to submit the attached report required by the Duane Arnold Energy Center Technical Specifications (TS) Section 5.6.6, Post Accident Monitoring (PAM) Report. This letter makes no new commitments or changes to any existing commitments. If you have any questions, please call Mike Davis, Licensing Manager at (319) 851-7032.
Dean Curtland Site Director, Duane Arnold Energy Center NextEra Energy Duane Arnold, LLC
Enclosure:
Technical Specification 5.6.6 Post Accident Monitoring (PAM) Report cc:
Administrator, Region Ill, USNRC Project Manager, DAEC, USNRC Resident Inspector, DAEC, USNRC NextEra Energy Duane Arnold, LLC, 3277 DAEC Road, Palo, IA 52324
BLIND CARBON COPY LIST FOR NG-19-0077 June 6, 2019 DAEC-CTS Project M. Strope (electronic)
M. Davis (electronic)
P. Hansen (electronic)
Central Iowa Power Cooperative (electronic)
Corn Belt Power Cooperative (electronic)
GOS (electronic)
SUBJECT:
Technical Specifications 5.6.6 PAM 14 Day Report
Enclosure to NG-19-0077 Technical Specification 5.6.6 Post Accident Monitoring (PAM) Report 2 pages follow
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Background===
Enclosure to NG-19-0077 Technical Specification 5.5.6 Post Accident Monitoring (PAM) Instrumentation 14-Day Report The primary purpose of the PAM instrumentation is to display plant variables that provide information required by the control room operators during accident situations.
This information provides the necessary support for the operator to determine that the actions automatically initiated by the Engineered Safety Features (ESF) equipment have successfully accomplished their safety functions for Design Basis Events.
Main Steam Isolation Valve (MSIV) position is a Type B, Category I variable provided for verification of containment integrity. In the case of MSIV position, the important information is the isolation status of the containment penetration. For the Duane Arnold Energy Center (DAEC), the Primary Containment Isolation Valve (PCIV) position PAM instrumentation consists of the individual open (i.e., red) and closed (i.e.,
green) position indicating lights for each active PCIV. These indicating lights are located on various control panels in the control room.
On May 4, 2019 at 2059, while operating at 100% power, the 'D' Main Steam Line Outboard Isolation Valve (MSIV), CV4421, closed indication light (green light) was found lit, with the open indicating light (red light) lit, indicating dual valve position.
Operators immediately confirmed that there were no other indications that the 'D' Outboard MSIV had left its full open position. Specifically, operators verified that there were no changes in main steam flow, reactor power, or reactor pressure. Subsequent investigation determined the cause was from the failure of 'D' Outboard MSIV Closed Position Switch, ZS4421 B. This failure required entry into Technical Specifications (TS) Limiting Condition for lnoperability 3.3.3.1, PAM Instrumentation, Condition A; One or more Functions with one required channel inoperable. Condition A requires restoration of the required indication channel to an Operable status within 30 days.
Resolution of the issue within 30 days (June 3, 2019) was not achieved, then requiring, per TS 3.3.3.1 Condition B, that a report be submitted within the following 14 days in accordance with TS Section 5.6.6. "PAM Report".
The TS 5.6.6 PAM report requirement states the cause of the inoperability is to be discussed along with plans for restoration. The report requirement also assumes the condition has not been corrected and as such calls for outlining alternate monitoring methods and their equivalency to the lost function, or justification of non-equivalency.
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Enclosure to NG-19-0077 Cause of the lnoperability The cause of the inoperability is the failure of ZS4421 B, Position Indicating Switch for CV4421, 'D' Main Steam Line Outboard Isolation Valve (MSIV). This limit switch is located inside the Steam Tunnel and the failure will be determined via maintenance activities during the next Forced Outage.
Preplanned Alternate Methods of Monitoring The failed limit switch provides indication of isolation status of the 'D' Main Steam Line. Both the open and closed position indications for the 'D' Inboard MSIV remain operable. These PAM instruments provide redundant status of the isolation status of the 'D' Main Steam Line. In addition, other control room indications are available to support isolation status. These included the_ 'D' Main Steam line flow indications.
Degree of Equivalence of alternate indication The 'D' Inboard MSIV position indications are a Type B, Category I variable in accordance with Regulatory Guide 1.97, and therefore, are fully equivalent indication of the isolation status of the 'D' Main Steam Line.
Plans and Schedule for Resolving the Operable but Degraded Condition Work Order 40662931 is currently scheduled to repair limit switch (ZS4421 B) during the next Forced Outage.
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