ML25167A043
| ML25167A043 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 06/26/2025 |
| From: | Constellation Energy Generation |
| To: | Division of Operating Reactor Licensing |
| Klett, AL | |
| References | |
| EPID L-2025-LRM-0076 | |
| Download: ML25167A043 (1) | |
Text
Limerick Revise Operability Requirement for Standby Gas Treatment System (SGTS)
June 26, 2025
- Introductions
- Meeting Objectives
- Background Information
- Scope of Technical Specification Changes
- Justification
- Overview of Submittal Schedule
- Summary and Wrap-up
- Questions Agenda 1
Limerick LAR to Revise TS 3.6.5.3 (SGTS)
Corporate Licensing Engineers -Lane Oberembt Corporate Licensing Senior Manager - Wendi Para Corporate/Limerick Risk Engineer - Suzanne Loyd, Connelly Richards Limerick Regulatory Assurance Manager - Jordan Rajan Limerick Regulatory Assurance Engineers - George Budock, Renee Guy Limerick Operations - Sagar Patel, J.D. Williamson Limerick SGTS Engineer - John Creamer
Introductions
2 Limerick LAR to Revise TS 3.6.5.3 (SGTS)
- Present information to the NRC to provide a clear understanding of the proposed Limerick License Amendment Request (LAR)
- The proposed change adds a footnote to SR 4.6.5.3.d.2 to state that automatic initiation and manual start from the control room are not required for one Standby Gas Treatment Subsystem when manually isolated while the other subsystem is in service for purging, inerting or de-inerting.
- This change is required for protection of the associated ductwork
- Obtain feedback from the NRC on the proposed LAR to ensure a high-quality submittal and support efficient use of resources, both NRC & Constellation.
- Establish a mutual understanding of the proposed schedule and corresponding need date to ensure adequate NRC resource availability Meeting Objectives 3
Limerick LAR to Revise TS 3.6.5.3 (SGTS)
- LCO 3.6.5.3 requires, Two independent standby gas treatment subsystems shall be OPERABLE in OPERATIONAL CONDITIONS (OPCON) 1, 2, or 3 and when (1) irradiated fuel is being handled in the refueling area secondary containment, or (2) during CORE ALTERATIONS.
- OPERATIONAL CONDITIONS (OPCON) equivalent to MODE
- During plant startup after an outage, inspections and work are continuing in the drywell and containment. The air is continuously purged to maintain a habitable environment for personnel. To minimize the possibility of any radioactive release, the air is routed through the in-service SGTS filter train.
Background Information 4
Limerick LAR to Revise TS 3.6.5.3 (SGTS)
- The second, standby, train of SGTS is isolated via associated hand switch and manual slide gates to prevent possible damage if a DBA LOCA or HELB in OPCON 1, 2, or 3 were to occur. These slide gates prevent the duct work and filter housing from being damaged due to the pressure surge of the accident while containment purging is in-service.
- Procedural steps exist to align this isolated SGTS train if it is emergently required to be put into service.
- Based on this isolation, the train is declared inoperable when LCO 3.6.5.3 is not met.
- In this condition, Limerick cannot change OPCONs during startup without either:
- Securing the purge, re-opening the slide gates and re-aligning plant equipment to restore the standby SGTS to OPERABLE status, or
- Using LCO 3.0.4.b, performing an associated risk assessment and, if acceptable, changing OPCONs and entering the action.
Background Information cont.
Limerick One-Time Extension of Type A (ILRT) LAR 5
- Prior to 2020, Limerick entered LCO 3.0.4.b to change OPCONs during startup when purging containment.
- Limerick incorporated TSTF-359 into their TS in 2004 (Amds. 169 and 132, for U1 and U2, respectively)
- TSTF-359 Increase Flexibility in Mode Restraints revised LCO 3.0.4 to allow entry into a OPCON when an LCO was not met. One option was performance of a risk assessment as outlined in LCO 3.0.4.b.
- TSTF-359 states, Adoption of LCO 3.0.4.b would result in this consideration applying to assessments for planned activities, as well as emergent conditions.
- In 2020, a concern was raised by an NRC Inspector about repeated use of LCO 3.0.4.b for routine/planned evolutions since this practice was not in accordance with NEI 03-10.
- NEI 03-10 was issued in 2003 to provide industry implementation guidance for TSTF-359.
- NEI 03-10 states, It is not intended for routine use.
- The Limerick Licensing Basis does not reference NEI 03-10.
- TSTF-359, the TS and TS Bases, and the staff's SE for TSTF-359 do not state the provision cannot be used for routine use.
Background Information cont.
Limerick One-Time Extension of Type A (ILRT) LAR 6
- Since 2020, Limerick has reverted to securing purging operations, unisolating the standby train of SGTS, declaring it operable, making the OPCON change, re-isolating the train of SGTS, and restart purging.
Background Information cont.
Limerick One-Time Extension of Type A (ILRT) LAR 7
- The LAR would add a footnote to SR 4.6.5.3.d.2 to state it is not required for one Standby Gas Treatment Subsystem which is manually isolated while the other subsystem is in service for purging, inerting or de-inerting.
- - Not required for one Standby Gas Treatment Subsystem manually isolated while the other subsystem is in service for purging, inerting or de-inerting containment.
- The change would require the standby SGTS train to be fully functional except for automatic initiation and manual start from the control room.
Scope of Technical Specification Changes 8
Limerick LAR to Revise TS 3.6.5.3 (SGTS)
- The physical act of turning the Mode Switch from 3 to 2 or 2 to 1 does not change the plant configuration in such a way as to make operability of the second train of SGTS more important than it was prior to the switch being manipulated.
- Reducing unnecessary component manipulations during critical plant evolutions will enhance the overall safety of the plant startup.
- The station will remain in the 7-day action during OPCON change rather than restart the action after the OPCON change when the system is again declared inoperable due to the manual slide gates being re-closed.
- Information provided by the Probabilistic Risk Analysis (PRA) shows there is no safety significance to SGTS as measured relative to Core Damage Frequency (CDF). Similarly, there are no SGTS functions that mitigate Large Early Release Frequency (LERF) scenarios.
Justification Limerick LAR to Revise TS 3.6.5.3 (SGTS) 9
- Pre-submittal Meeting with NRC to discuss LAR - June 26, 2025
- Request NRC approval by April 15, 2026, to support plant startup from Limerick Refueling Outage Li1R21 (spring 2026).
Overview of Submittal Schedule 10 Limerick LAR to Revise TS 3.6.5.3 (SGTS)
- Add a footnote to SR 4.6.5.3.d.2 to state that automatic initiation and manual start from the control room are not required for one Standby Gas Treatment Subsystem when manually isolated while the other subsystem is in service for purging, inerting or de-inerting to maintain a habitable work environment.
- Approval would minimize distracting plant evolutions during plant startup.
- Approval would help eliminate the increased risk of equipment inoperability due to component manipulation.
Summary and Wrap-up 11 Limerick LAR to Revise TS 3.6.5.3 (SGTS)
Questions?
Limerick One-Time Extension of Type A (ILRT) LAR 12
Supplemental Information Limerick LAR to Revise TS 3.6.5.3 (SGTS) 13
Supplemental Information 14 Limerick LAR to Revise TS 3.6.5.3 (SGTS)
LCO 3.0.4 (Unit 1 & Unit 2)
Supplemental Information 15 Limerick LAR to Revise TS 3.6.5.3 (SGTS)
Unit 1 & 2 SR 4.6.5.3.d.2 Supplemental Information cont.
16 Limerick LAR to Revise TS 3.6.5.3 (SGTS)