ML22271A750

Preapplication Meeting Slides: Technical Specification Change to Support Elimination of ESFAS Single Point Vulnerability

ML22271A750
Person / Time
Site:	Waterford
Issue date:	09/29/2022
From:	Entergy Operations
To:	James Drake NRC/NRR/DORL/LPL4
Drake J, NRC/NRR/DORL/LPL4
References
Download: ML22271A750 (29)

Text

TECHNICAL SPECIFICATION CHANGE TO SUPPORT ELIMINATION OF ENGINEERED SAFETY FEATURES ACTUATION SYSTEM SINGLE POINT VULNERABILITY WATERFORD 3 September 29, 2022

2 Technical Specification Change to Support Elimination of Engineered Safety Features Actuation System Single Point Vulnerability Pre-Submittal Meeting Agenda ESFAS Design PPS Design Issue of Concern

Background

Planned Modification Technical Specification Change Closing

3 ESFAS Design

4 ESFAS Design

• Engineered Safety Features Actuation System (ESFAS) is part of the Plant Protection System (PPS)

• The PPS can be broken down into two subsystems; Reactor Protective System (RPS)

ESFAS

• The ESFAS generates actuation signals for the Engineered Safety Features (ESF) and ESF support systems to mitigate the consequences of accident conditions.

5 ESFAS Design The following is a list of the ESFAS signals:

• Safety Injection Actuation Signal (SIAS)

• Containment Isolation Actuation Signal (CIAS)

• Containment Spray Actuation Signal (CSAS)

• Main Steam Isolation Signal (MSIS)

• Recirculation Actuation Signal (RAS)

• Emergency Feedwater Actuation Signal for SG 1 (EFAS-1)

• Emergency Feedwater Actuation Signal for SG 2 (EFAS-2)

6 PPS Design

7 PPS Design

8 Issue of Concern

9 Issue of Concern The following ESFAS signals have SPV identified in their circuitry (1 out of 1 Logic):

• Main Steam Isolation Signal (MSIS)

K305A or B and K313A or B Actuation Relay failure will close Main Steam Isolation Valve (MSIV), Feedwater Isolation Valve (FWIV), Feedwater Regulating Valve, and Feedwater Startup Regulating Valve

• Closure of a single MSIV will result in asymmetric steam generator transient (ASGT), resulting in a Core Protection Calculator (CPC) Auxiliary Trip (reactor trip) on Low DNBR and High Local Power Density.

• If closure of both MSIVs are affected, then there will be a complete loss of heat sink, and the RCS pressure safety limit will be challenged, resulting in a reactor trip on High Pressurizer Pressure.

10 Issue of Concern

• Containment Spray Actuation Signal (CSAS)

K114A or B Actuation Relay failure will close Component Cooling Water (CCW) flow to the non-critical loop.

This will result in loss of CCW flow to the Reactor Coolant Pumps (RCPs) and the Control Element Drive Mechanism (CEDM) cooling coils. Loss of seal cooling to the RCP can result in serious RCP seal damage, with the potential for a small break LOCA.

12 Background

• A license amendment request (LAR) was submitted on December 6, 2017 (ML17340B321) as supplemented by letter dated June 29, 2018 (ML18180A271) to support installation of the new design in RF-22 (2019).

• The LAR was later withdrawn (ML18354B283) due to parts unavailable to implement design change during RF-22.

• Before this LAR was withdrawn, the NRC staff had conducted a partial review of the technical aspects of the request. This review is documented in an internal memorandum, which is located under ADAMS Accession No. ML18362A312 (not publicly available).

• Proposed resubmitted LAR makes no technical changes to previous (withdrawn) LAR submittal as supplemented.

13 Planned Modification

14 Planned Modification Modify ESFAS MSIS and CSAS Circuits

• Revise the ESFAS Actuation Circuit from a 1 out of 1 logic (Slide 14) to a parallel 2 out of 2 logic (Slide 15).

Removed the SPV from the circuit Parallel 2 out of 2 logic meets the Reg Guide 1.22 requirements

• Add an LED Test Fixture with an LED to illuminate when an ESFAS Actuation Relay Contact closes.

Provides indication of failed relay Provides safe means to test without need for intrusive maintenance using meters for voltage and continuity checks

• Modification will be implemented under 10 CFR 50.59

15 1 out of 1 Logic - Simplified View

16 Parallel 2 out of 2 Logic (Trip Hardening) - Simplified View

17 Resolution - Parallel 2 out of 2 Logic With Test Panel

18 125VDC Test PushButton Testing LED Lights

19 125VDC Test PushButton Testing of Actuation Relay

20 125VDC Test PushButton Testing of Actuation Relay

21 125VDC Test PushButton ESFAS Actuation

22 Technical Specification Change

23 Technical Specification Change 23 Remove ESFAS Relays K305, K313, K114 from Technical Specification Table 4.3-2 Note 3 which removes the exemption from online testing that was necessary because of the previous 1 out of 1 logic.

This will change the test frequency of ESFAS Relays K305, K313, K114 (and the added MSIS & CSAS Relays) to the frequency established by the Surveillance Frequency Control Program.

24 Technical Specification Change 24 Markup of Current Technical Specification Table 4.3-2 Note 3

25 Closing

26 Closing

• The planned ESFAS circuit modification will:

Eliminate identified Single Point Vulnerability A single failure of a component in the test circuit will not cause an actuation.

Allow for non-intrusive, safe method for testing on-line Identify a failure of an ESFAS Actuation Relay Comply with Reg. Guide 1.22 Be implemented under 10 CFR 50.59 26

27 Closing

• LAR updates TS testing requirements consistent with Surveillance Frequency Control Program and Reg. Guide 1.22 to support planned ESFAS circuit modification

• LAR does not request NRC approval of modification

• Proposed resubmitted LAR makes no technical changes to previous LAR submittal

• Expected submittal date is October 2022

• LAR approval needed to support startup from Fall 2023 refueling outage (RF-25)

28 Conclusion Thank you for your time and attention.

Questions?

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