ML24319A149
| ML24319A149 | |
| Person / Time | |
|---|---|
| Site: | Technical Specifications Task Force |
| Issue date: | 11/14/2024 |
| From: | Technical Specifications Task Force |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| Download: ML24319A149 (1) | |
Text
Technical Specifications Task Force A Joint Owners Group Activity TSTF 1
Discussion of TSTF-502-T, Correct Containment Isolation Valve Bases Regarding Closed Systems
Technical Specifications Task Force A Joint Owners Group Activity TSTF Introduction
- In 2007, the TSTF approved TSTF-502-T, "Correct Containment Isolation Valve Bases Regarding Closed Systems."
- TSTF-502 made the following change to the PWR TS 3.6.3, "Containment Isolation Valves," and BWR TS 3.6.1.3, "Primary Containment Isolation Valves," (PCIVs) LCO Bases:
"The normally closed isolation valves are considered OPERABLE when manual valves are closed, automatic valves are de-activated and secured in their closed position, and blind flanges are in place, and closed systems are intact. These passive isolation valves/devices are those listed in Reference 2."
- Reference 2 is FSAR, Section [6.2].
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Technical Specifications Task Force A Joint Owners Group Activity TSTF
Background
- The CIV/PCIV LCOs require each [primary] containment isolation valve ([P]CIV) shall be operable.
- The LCO does not address closed systems.
- The SRs test purge valves, manual valves and blind flanges, automatic power operated valves, check valves, traversing incore probe shear isolation valves, excess flow check valves, and MSIVs.
- There are no SRs on closed systems.
- NUREG-1430 and NUREG-1432 Actions for penetrations with a single CIV have a Condition Note that states, Only applicable to penetration flow paths with only one containment isolation valve and a closed system.
- NUREG-1431, NUREG-1433, and NUREG-1434 have Actions for penetrations with a single [P]CIV, but do not mention closed systems.
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Technical Specifications Task Force A Joint Owners Group Activity TSTF Problem Statement
- The TS LCO Bases refer to intact closed systems, but there are no LCO or SR requirements that establish what constitutes an intact closed system.
- Does intact mean zero leakage, insignificant leakage, leakage less than the design basis, or gross failure? Is it related to assumed containment leakage under Appendix J?
- There are no Actions that apply if its determined that a closed system is not intact.
- This leaves licensees wondering how to determine if a closed system is "intact" and what action to follow if it is not (or whether to enter LCO 3.0.3).
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Technical Specifications Task Force A Joint Owners Group Activity TSTF Historical Requirements
- Prior to implementation of Generic Letter 91-08, "Removal of Component Lists from Technical Specifications," the TS contained a table of CIVs.
- A review of representative plant TS did not find any tables that listed closed systems.
- The GL stated, With this TS change, the LCO, remedial actions, and surveillance requirements will apply for all valves that are classified as containment isolation valves by the plant licensing basis.
- A review of representative FSAR lists of CIVs did not find any that listed closed systems, only valves.
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Technical Specifications Task Force A Joint Owners Group Activity TSTF Origins of the Closed System Reference
- Some plants utilize GDC 57, Closed System Isolation Valves, which states:
- Each line that penetrates primary reactor containment and is neither part of the reactor coolant pressure boundary nor connected directly to the containment atmosphere shall have at least one containment isolation valve which shall be either automatic, or locked closed, or capable of remote manual operation. This valve shall be outside containment and located as close to the containment as practical. A simple check valve may not be used as the automatic isolation valve.
- In other words, if a penetration is connected to a closed system that meets the criteria, the penetration design is only required to have one CIV.
- When a TS Action refers to a penetration with a single CIV, that penetration is a GDC 57 CIV. The B&W and CE Actions make reference to the closed system design, but the W and BWR Actions do not.
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Technical Specifications Task Force A Joint Owners Group Activity TSTF Actions When a GDC 57 Credited Closed System is Not Intact
- Leakage from a closed system may affect the operability of the system itself, which may be the subject of other specifications.
- If closed system leakage results in exceeding the containment leakage rate, La, the Containment TS applies.
- If a closed system is not "intact," the condition would be evaluated against any applicable system TS and evaluated under the Corrective Action Program.
- Leakage from closed systems will be governed by ASME requirements on Code Class 1, 2, and 3 systems. Also, the ASME requirements on structural integrity may apply.
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Technical Specifications Task Force A Joint Owners Group Activity TSTF Conclusion
- The CIV LCO and SRs do not apply requirements on closed systems.
- There are no CIV Actions on closed systems.
- Historically and currently, plants lists of CIVs do not include closed systems.
- The discussion of closed systems in the Bases reflects the GDC 57 design allowance for penetrations connected to some types of closed system to have a single CIV. This does not make the closed system subject to the CIV TS requirements.
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