ML25219A024

TSTF-585 Final RAIs

ML25219A024
Person / Time
Site:	Technical Specifications Task Force
Issue date:	08/07/2025
From:	Office of Nuclear Reactor Regulation
To:	Technical Specifications Task Force
References
EPID L-2023-PMP-0000
Download: ML25219A024 (2)

Text

REQUEST FOR ADDITIONAL INFORMATION TECHNICAL SPECIFICATIONS TASK FORCE TSTF-585, REVISION 4, REVISE LCO 3.0.3 TO REQUIRE MANAGING RISK" (EPID: L-2023-PMP-0000)

INTRODUCTION By letter dated March 7, 2025 (Agencywide Documents Access and Management System Accession No. ML25066A098) the Technical Specifications Task Force (TSTF) submitted traveler TSTF-585, Revision 4, Revise LCO 3.0.3 to Require Managing Risk. The U.S. Nuclear Regulatory Commission (NRC) staff requires the following additional information complete our review of the traveler.

REQUESTS FOR ADDITIONAL INFORMATION

1) There are several risk assessment elements in the NUMARC 93-01, Revision 4F guidance that could be interpreted by a licensee as being optional when performing the risk assessment since the guidance says the risk assessment should rather than shall or must consider these elements. In addition, the traveler itself also introduces elements that say should instead of shall or must. The guidance language represents an oversight issue for the NRCs Reactor Oversight Process since the vague guidance could create challenges for enforceability when used as a technical specification requirement. Since the methodology would now be used to make a technical specification decision as to whether an extended Completion Time of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is acceptable, the staff believes that the methodology (when used as an LCO 3.0.3 requirement) must require a minimum acceptable level of rigor and uniformity for licensees that adopt TSTF-585. Accordingly, the risk assessment must, as a minimum:

a. Assess the elements cited in NUMARC 93-01, Section 11.3.2, General Guidance for the Assessment - Power Operations and Shutdown, Paragraphs 2, 6, and 8 for quantitative assessments. These factors must be considered to ensure that LCO 3.0.3 risk assessments provide an appropriate level of rigor and would be implemented uniformly across the operating reactor fleet.

b. Assess the elements in NUMARC 93-01, Section 11.3.7.1, Establishing action thresholds based on qualitative considerations. These elements must be considered in a qualitative risk assessment.

c. Assess non-quantifiable factors. Section 3.2.2 of TSTF-585 states, Consistent with the NUMARC guidance, non-quantifiable factors must also be assessed. The staff agrees with this statement. However, all of the STS Bases are marked up to say that non-quantifiable factors should be assessed.

d. Assess the configuration-specific core damage frequency (CDF) and large early release frequency (LERF). Section 3.2.2 of TSTF-585 and the STS Bases markup state this should be done.

Please update the traveler and/or the model application to require these elements to be considered in every LCO 3.0.3 risk assessment.

2) TSTF-585 proposes a change to each the STS LCO 3.0.3 Bases that states, The determination that continuing operation is acceptable should be documented in sufficient detail to allow a knowledgeable individual to understand the basis for the determination

[Emphasis added]. In order to ensure that there is adequate documentation for NRC inspectors to evaluate the licensee response to an LCO 3.0.3 entry, the licensing basis for a plant adopting TSTF-585 must require this documentation (i.e., change the word should to shall or must). Please update the traveler and model application to reflect this requirement.

3) Section 3.2.2 of TSTF-585 states, Whenever practicable, the Maintenance Rule risk assessment tools will be used to determine a quantitative value for risk. Similarly, TSTF-585 modifies each of the STS LCO 3.0.3 Bases to state, Whenever practicable, a quantitative value for risk should be determined. If determination of a quantitative value for risk is not practicable, a qualitative assessment of risk may be used with appropriate consideration of the plant conditions and uncertainties to determine whether continued operation for a limited time is acceptable. To ensure that the risk assessment is performed with an appropriate level of rigor and to minimize potential for human error, the licensing basis should require the numeric determination whenever possible. Accordingly, this statement should be revised to state whenever the plants PRA model is available, a quantitative value for risk shall Qualitative assessment shall only be used to make necessary adjustments to the numeric determination to factor in plant conditions that are not modeled in the PRA (e.g., control room ventilation inoperability) or when the PRA model is not available. Please update the traveler to reflect this change.