ML23033A384

February 9, 2023, Meeting Handout: NRC Staff Comments on TSTF-576 Revision 2 (Draft), SRV Requirements

ML23033A384
Person / Time
Site:	Technical Specifications Task Force
Issue date:	02/02/2023
From:	NRC/NRR/DSS/STSB
To:
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Download: ML23033A384 (1)

Text

TSTF-576, Revision 2 (draft), Revise Safety/Relief Valve Requirements (ADAMS Accession No. ML23019A253)

NRC staff feedback to the Technical Specifications Task Force (TSTF) for meeting on February 9, 2023

Background:

Some Boiling Water Reactor plants experience safety/relief valves (SRVs) lifting outside the technical specification (TS) allowable tolerances during post-cycle testing. When this occurs, licensees are required to submit licensee event reports (LERs) (>40 LERs over the past 10 years). These evaluations consistently demonstrate that the specified safety function relating to reactor coolant system overpressure protection was maintained, despite exceeding the tolerances allowed in the relevant surveillance requirement (SR). Industry and the NRC staff have been working to develop a resolution for the issue since late 2019.

Current TSTF Proposal: The TSTF is proposing to change the existing SR in the TS for the SRVs and:

• limit the scope to confirming the as-left setpoints are within acceptable tolerance

• move the SRV as-found lift pressure acceptance criteria from TS to a licensee-controlled document and evaluate performance at a system level Summary of Technical Issue: The existing SR in TS specifies acceptance criteria for the as-found condition of the valves at +/-3% over their setpoints. This supports meeting the limiting condition for operation (LCO) for reactor coolant system (RCS) overpressure and was also determined by staff to ensure that assumptions and inputs for any secondary analyses (containment integrity, etc.) are bounded.

Questions for the TSTF:

In general, demonstrating that the RCS overpressure LCO is met using a system-based approach may be acceptable. However, NRC staff needs to clearly understand the relationship between the new system-based acceptance criteria and other parts of the licensing bases. The following questions will help provide context:

1. Are the proposed acceptance criteria for as-found lift pressures also relied on to demonstrate that secondary requirements are met? If so, how was that conclusion reached (similar to the analyses done for the earlier 1% to 3% change)?

2. If not, how will licensees determine that other licensing and design basis requirements dependent on as-found valve lift pressure are met? Most of these requirements are at a system level, but SRV discharge line dynamic loading may need to be considered at the SRV-specific level.