ML21335A077

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Dec 07 2021 LGS Digital Modernization Pre-submittal Meeting Slides
ML21335A077
Person / Time
Site: Limerick  Constellation icon.png
Issue date: 12/07/2021
From: Rhoades D
Exelon Generation Co, Exelon Nuclear
To: Marshall M
Plant Licensing Branch 1
Sreenivas V, NRR/DORL/LPLI, 415-2597
References
Download: ML21335A077 (33)
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Text

Limerick Generating Station Digital Modernization Project LAR Technical Specifications Changes NRC Pre-submittal Meeting December 7, 2021

Agenda / Opening Remarks

-Introductions

-Current Limerick Technical Specifications (TS)

-Limerick Digital Upgrade Project

-Changes to Make the Limerick TS More Consistent with ITS

-Changes to the Limerick TS To Reflect the Upgraded Design

-TS Presentation in the LAR

-Next Steps 1

Introductions - Exelon Project Team Licensing Darani Reddick, Licensing Director Dave Helker, Licensing Manager Frank Mascitelli, Licensing Lead George Budock, LGS Regulatory Assurance Pareez Golub, Digital Licensing SME Brian Mann, Technical Specifications SME Engineering John Connelly, Central Design Organization (CDO) Manager Mark Samselski, CDO - Lead Responsible Engineer George Bonanni, CDO - Senior Staff Engineer Mike Foote, CDO - Senior Staff Engineer Scott Schumacher, Systems Engineering 2

(continued)

Introductions - Exelon Project Team Project Management Steve Hesse, Project Director Dave Molteni, Senior Manager and Station Lead Jerry Segner, Principal Project Manager Kayla Marriner, Project Manager Operations Paul Krueger, Operations 3

(continued)

Introductions - Westinghouse Project Team Project Management Tom Pietryka, Program Manager Engineering Terry Tuite, PPS Lead - Engineering Warren Odess-Gillett, Lead - Licensing Cal Tang, BWR Technical Advisor 4

Current Limerick Technical Specifications (TS) 5

Limerick Existing TS Overview

  • Limerick is a two-unit BWR/4 plant with TS based on NUREG-0123, Standard Technical Specifications for General Electric Boiling Water Reactors.
  • Significant differences between the Limerick TS and BWR/4 TS based on the improved STS (NUREG-1433):
  • Limiting Safety System Setting (LSSS) Section in Chapter 2
  • Instrumentation TS include trip setpoints and response time limits
  • Instrumentation TS typically include four tables:

- Table 1 - Function, Minimum Operable Channels per Trip System, Operational Condition, Actions

- Table 2 - Trip Setpoint and Allowable Value

- Table 3 - Response Time Limits

- Table 4 - Surveillance Requirements

  • Tables have lists of Actions and make extensive use of footnotes 6

Limerick Digital Modernization Project 7

Project Overview

  • The Limerick project is a pilot for future digital modernization projects at other Exelon sites and for other plants.
  • An integrated digital Plant Protection System (PPS) replaces the analog systems that provide:
  • Nuclear Steam Supply Shutoff System (NSSSS) (isolation) instrumentation
  • End-of-Cycle Recirculation Pump Trip (EOC RPT) instrumentation
  • Upgrades analog Redundant Reactivity Control System (RRCS) to digital (ATWS).
  • Most logic changed from typical BWR one-out-of-two-taken-twice to two-out-of-four.

8

9 Trip Logic TRIP LOGIC One-Out-Of-Two-Taken-Twice Channel A Channel B Channel C Channel D Trip Unit 1 Trip Unit 2 Trip Two-Out-Of-Four Channel A Channel B Channel C Channel D Trip

Changes to Make the Limerick TS More Consistent with ITS 10

Move LSSS Table to Instrumentation Chapter

  • The existing Limerick LSSS section contains a table of functions but references TS 3.3.1 for Actions and Surveillances.
  • The LAR will retain the Limerick LSSS section, but the table of function will be moved to the instrumentation section.
  • Consistent with ITS.
  • Supports other project changes to the TS.
  • Improves useability of TS.
  • Provides better model TS for future digital upgrades.

11

Relocate Trip Setpoints to Licensee Control

  • The BWR STS (NUREG-1433) only contains Allowable Values. Trip setpoints were relocated to licensee control.
  • The Limerick TS contain both Trip Setpoints and Allowable Values.
  • The LAR will relocate trip setpoints to licensee control.

The LAR will either reference previous amendments in which the NRC approved the application of the trip setpoint methodology or will describe the applicable trip setpoint methodology.

Change is:

Consistent with ITS.

Supports other project changes to the TS.

Provides better model TS for future digital upgrades.

12

Relocate Response Time Limits to Licensee Control

  • The BWR STS (NUREG-1433) requires response time testing, but the limits are relocated to licensee control.
  • The Limerick TS contains response time limits.
  • Response time limits will be relocated to licensee control following the guidance in Generic Letter 93-08, Relocation of Technical Specification Tables of Instrument Response Time Limits.

Change is:

Consistent with ITS.

Supports other project changes to the TS.

Provides better model TS for future digital upgrades.

13

Create a Loss of Power TS

  • The BWR STS (NUREG-1433) requirements on Loss of Power instrumentation (Degraded Voltage and Loss of Voltage) are in a separate specification.
  • The Limerick TS 3.3.5, ECCS Instrumentation, contains functions for Degraded Voltage and Loss of Voltage.
  • The LAR will move the Loss of Power requirements to a separate specifications, consistent with the ITS, without change except to relocate the trip setpoints to licensee control.

Change is:

Consistent with ITS.

Supports other project changes to the TS.

Simplifies the PPS specifications.

Provides better model TS for future digital upgrades.

14

Changes to the Limerick TS To Reflect the Upgraded Design 15

16 SENSORS & LOGIC A, B, C, D Reactor Vessel Water Level - Low, Level 3 A, B, C, D Drywell Pressure - High A, B, C, D Reactor Vessel Steam Dome Pressure - High

Actuation Logic ACTUATED SYSTEM RPS Trip Units TS 3.3.1, Reactor Protection System A, B, C, D Reactor Vessel Water Level - Low, Level 2 A, B, C, D Drywell Pressure - High A, B, C, D Main Steam Line Pressure - Low

Actuation Logic Isolation Valves TS 3.3.2, Isolation Actuation Instrumentation A, B, C, D Reactor Vessel Water Level - Low, Level 1 A, B, C, D Drywell Pressure - High A, B, C, D Condensate Storage Tank Level - Low

Actuation Logic Core Spray System, Low Pressure Coolant Injection System, High Pressure Coolant Injection System, Automatic Depressurization System, EDG TS 3.3.3, ECCS Actuation Instrumentation The Surveillances in each specification test from the sensor to the actuated system (Channel Calibration, Response Time Test, Logic System Functional Test).

The Actions in each specification are based on the ability of the operable sensors to initiate the one-out-of-two-taken-twice logic to initiate the supported system.

Each specification is independent, even though the specifications are based on many of the same parameters.

CURRENT TS DESIGN A, B, C, D Reactor Vessel Water Level - Low, Level 2 A, B, C, D Condensate Storage Tank Level - Low

Actuation Logic TS 3.3.5, RCIC Actuation Instrumentation RCIC SPECIFICATION Dotted Lines Indicate Separation of Specifications

17 A

Comparators B Comparators C Comparators D

Comparators CHANNELS A Drywell Pressure - High A Condenser Vacuum - Low A MSL Pressure - Low

B Drywell Pressure - High B Condenser Vacuum - Low B MSL Pressure - Low

C Drywell Pressure - High C Condenser Vacuum - Low C MSL Pressure - Low

D Drywell Pressure - High D Condenser Vacuum - Low D MSL Pressure - Low

Division 1 Actuation Logic DIVISIONS Division 2 Actuation Logic Division 3 Actuation Logic Division 4 Actuation Logic All Comparators Communicate with All Divisions All the Sensors in a Channel Communicate with that Channels Comparators ACTUATED SYSTEMS Different Divisions Communicate with Different Devices RPS Trip Units (Div 1 or 3 Half-Scram Div 2 or 4 Half-Scram)

HPCI (Div 2&4)

RCIC, ADS (Div 1&3)

LPCI, CS, EDG, Isolation Valves (Div 1, 2, 3, 4)

REVISED TS DESIGN Dotted Lines Indicate Separation of Specifications

New TS Organization

  • To reflect the new design, the Section 3.3 TS are reorganized:

3.3.1 Plant Protection System Instrumentation Channels 3.3.1 Reactor Protection System Instrumentation 3.3.2 Plant Protection System Divisions 3.3.2 Isolation Actuation Instrumentation 3.3.3 Reactor Trip Units 3.3.3 Emergency Core Cooling System Actuation Instrumentation 3.3.3.A Reactor Pressure Vessel (RPV) Water Inventory Control (WIC) Instrumentation 3.3.4.1 ATWS Recirculation Pump Trip System Instrumentation 3.3.4.2 End-of-Cycle Recirculation Pump Trip System Instrumentation 3.3.5 Loss of Power 3.3.5 Reactor Core Isolation Cooling System Actuation Instrumentation 3.3.6 Control Rod Block Instrumentation (Unchanged) 3.3.7 Monitoring Instrumentation (unchanged) 3.3.7.4 Remote Shutdown (Unchanged) 3.3.7.5 Accident Monitoring Instrumentation (Unchanged) 3.3.7.6 Source Range Monitors (Unchanged) 3.3.9 Feedwater/Main Turbine Tip System Actuation Instrumentation (Unchanged) 18

TS 3.3.1, Plant Protection System Instrumentation Channels

  • An arrangement of components and modules as required to generate a single protective action signal when required by a generating station condition. A channel loses its identity where single protective action signals are combined.

The TS will contain a single table that lists the sensor function, applicable operational condition, minimum operable channels, and allowable value.

Like the ITS, the specification will include the Actions and Surveillance Requirements instead of separate tables.

Average Power Range Monitor (APRM), Intermediate Power Range Monitors (IRMs), and Oscillation Power Range Monitor (OPRM) inputs are treated as channel inputs.

Only manual functions credited in the accident analysis (i.e., satisfying 10 CFR 50.36(c)(2)(ii) Criterion 2 or 3) are required.

19 (continued)

TS 3.3.1, Plant Protection System Instrumentation Channels Example Table (Format Only) 20 (continued)

TS 3.3.1, Plant Protection System Instrumentation Channels The TS will require three sensor channels to be operable for most four channel functions.

10 CFR 50.36(c)(i) states, Limiting conditions for operation are the lowest functional capability or performance levels of equipment required for safe operation of the facility.

Most sensor channels provide input to all divisions.

Only three channels are needed to meet all design requirements for voted channels.

Consistent with the regulations and the plant design, the 3.3.1, PPS Channel Instrumentation, LCO will only require three sensor channels to be operable for most functions.

All four channels are maintained and tested by the PPS.

Under the new TS, one channel can be removed for testing or otherwise be inoperable without entering an Action.

Simplifies the current TS which contains Actions and SR Notes to facilitate removing a channel from service for testing.

21 (continued)

TS 3.3.1, Plant Protection System Instrumentation Channels The Actions will not be based on the actuated system.

The typical Surveillance will be a calibration of the sensor to the input of the comparator.

The comparator is tested by the PPS self-test.

22

TS 3.3.2, Plant Protection System Divisions

  • The designation applied to a given system or set of components that enables the establishment and maintenance of physical, electrical, and functional independence from other redundant sets of components.

NOTEA division can have one or more channels.

  • The LCO will require all four divisions to be operable.
  • Still under development.

- May be an Allowable Value table for TS limits implemented in the division, such as timers.

- The TS will recognize that different divisions may support different actuated components.

23 (continued)

TS 3.3.2, Plant Protection System Divisions

  • The LAR will include revisions to certain TS Surveillance Requirements by crediting self-diagnostics of the digital platform:
  • Will credit NRC-approved WCAP-18461-P-A, Common Q Platform and Component Interface Module System Elimination of Technical Specification Surveillance Requirements
  • Will include analysis providing a comparison between the Limerick-specific design and the WCAP-18461-P-As scope
  • Draft analysis shows:

- Some SRs can be eliminated: Channel Checks, Channel Functional Tests, Logic System Functional Tests

- May add a new SR to test new design

- Reduce scope of response time testing 24

TS 3.3.3, Reactor Trip Units

  • New specification will be created that provides requirements on the trip system from the division reactor trip matrix through the scram valves.
  • Still under development 25

3.3.5, Loss of Power Instrumentation

  • Degraded voltage and loss of voltage functions moved from existing ECCS Actuation Instrumentation TS to a separate TS.
  • Consistent with the ITS.
  • Trip setpoints and response time limits relocated to licensee control.
  • Do not anticipate changing other requirements.

26

Other Changes

Instrumentation

  • Isolation functions are part of the digital modernization project, but TS requirements not incorporated into PPS TS.
  • Trip logic is changed from one-out-of-two-taken-twice to two-out-of-four.
  • Actions revised to reflect the new design.
  • 3.3.4.1, ATWS Recirculation Pump Trip System Instrumentation
  • The ATWS RPT system instrumentation is part of the digital modernization project but is not part of PPS.
  • Retained as a separate TS.
  • Trip logic is changed from one-out-of-two-taken-twice to two-out-of-four.
  • Actions revised to reflect the new design.
  • Trip setpoints and response time limits relocated to licensee control.
  • There will be changes to the defined terms to reflect the other TS changes.

27

TS Presentation in the LAR 28

TS Markup

  • The LAR TS markups will be similar to a TS conversion markup.
  • Current TS (CTS) markup showing disposition of requirements with numbered Discussions of Change (DOCs).
  • New TS markup showing origin of existing requirements and new requirements with numbered DOCs.

29

Next Steps 30

Next Steps

  • Arrange a follow-up meeting in mid-January to receive any NRC staff feedback.

31

Discussion 32

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