ML24289A034

Discussion of NRC Staff Comments on Draft TSTF-585, Revision 3, Revise LCO 3.0.3 to Require Managing Risk

ML24289A034
Person / Time
Site:	Technical Specifications Task Force
Issue date:	08/08/2024
From:	Technical Specifications Task Force
To:	Office of Nuclear Reactor Regulation
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Download: ML24289A034 (1)

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Technical Specifications Task Force A Joint Owners Group Activity TSTF 1

Discussion of NRC Staff Comments on Draft TSTF-585, Revision 3, "Revise LCO 3.0.3 to Require Managing Risk"

Technical Specifications Task Force A Joint Owners Group Activity TSTF

Background

• The existing LCO 3.0.3 requires a rapid plant shutdown regardless of the risk significance of the plant condition.

• Historical information has shown that about half of the plant shutdowns initiated under LCO 3.0.3 could be avoided if licensees had additional time to resolve the condition or obtain relief from the NRC.

• A rapid plant shutdown is a major plant evolution that exercises an array of plant equipment and procedures.

• Most TS-required equipment is in standby, and its inoperability does not threaten stable plant operation.

• A rapid shutdown may be unwarranted for a limited period of time if plant risk is determined to be acceptable and the required risk management actions are implemented.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF

Background

March 5, 2020 First presubmittal meeting October 29, 2020 Presubmittal webinar with NRC April 6, 2021 Provided draft TSTF-585, Rev. 0, "Revise LCO 3.0.3" June 7, 2021 NRC provided comments on draft November 30, 2021 Provided draft, TSTF-585, Rev. 1, "Provide an Alternative to the LCO 3.0.3 One-Hour Preparation Time" March 17, 2022 NRC provided comments on draft October 25, 2022 Workshop with NRC and PWROG RMC on use of Maintenance Rule tools for LCO 3.0.3 risk evaluation March 6, 2023 TSTF-585, Rev. 2, formally submitted to NRC.

July 17, 2023 TSTF/NRC teleconference. NRC suggested an alternative approach with a fixed time to assess risk and implement mitigating actions.

December 12, 2023 Provided draft TSTF-585, Rev. 3, "Revise LCO 3.0.3 to Require Managing Risk" March 7, 2024 NRC provided comments on draft 3

Technical Specifications Task Force A Joint Owners Group Activity TSTF

Background

At the October 25, 2022, workshop, the TSTF (supported by the PWROG Risk Management Committee) met with the NRC staff (including the staffs Maintenance Rule subject matter expert) and described how the 50.65(a)(4) risk evaluation tools could be used to assess plant risk when entering LCO 3.0.3.

- The traveler justification was expanded in Revision 3 to describe how the Maintenance Rule (MR) risk assessment and NUMARC 93-01 guidance would be used.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Purpose

• The purpose of todays meeting is to discuss the NRCs comments on draft TSTF-585, Rev. 3, to identify any changes to the traveler needed prior to submittal.

• The order of the NRCs comments has been changed to ensure there is sufficient time to discuss the comments that could have the largest effect on the traveler.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 1

1) All of the TS that result in default (no action specified for a condition) or direct entry into LCO 3.0.3 should be evaluated to determine whether the proposed LCO 3.0.3 is acceptable or if other actions should be taken. All of these should be evaluated for allowing the use of the proposed LCO 3.0.3 versus the existing LCO 3.0.3 actions (or using something different than LCO 3.0.3) and a justification should be provided. These should be reviewed by the Technical Branches.

Discussion There are innumerable reasons for entering LCO 3.0.3, and it is not possible to identify all of them. The type of item-by-item review suggested by the staff is impractical and the majority of the conditions would be of very low probability of occurrence. Such an approach is contrary to the NRC's goal of applying resources to risk-significant issues.

6 (continued)

Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 1 However, as discussed in Section 3.4.1 of the traveler justification, the TSTF performed a review of the STS and identified:

- Explicit entries into LCO 3.0.3 (9 TS)

- TS without Actions for obvious failures to meet the LCO (35 TS)

Each action was then evaluated considering:

- Could the Condition affect safe plant operation assuming no other failures or accidents?

- Could the Condition be assessed for its risk impact?

- Could the Condition be entered for failures that would not significantly degrade the ability of the system to perform its primary function?

- Are there proceduralized actions that can be taken to diminish the impact of the failure?

- Would an immediate plant shutdown be complicated by the failure?

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 1 Most TS Actions are amenable to entry into LCO 3.0.3 and performance of a risk assessment.

- The traveler justification provided example evaluations for ECCS, control room ventilation, AC Sources - Operating, and instrumentation.

A few Actions were determined to not be appropriate for the revised LCO 3.0.3, and changes to the TS are proposed to require a shutdown.

- NUREG-1430, TS 3.1.6, "AXIAL POWER SHAPING ROD (APSR) Alignment Limits"

- NUREG-1431, TS 3.6.10, "Hydrogen Ignition System (HIS)"

- NUREG-1430, NUREG-1431, and NUREG-1432, TS 3.7.2, "Main Steam Isolation Valves (MSIVs)"

- NUREG-1430 through NUREG-1434 TS 3.8.4, "DC Sources - Operating"

- NUREG-1430 through NUREG-1434 TS 3.8.9, and NUREG-2194 TS 3.8.5, "Distribution Systems - Operating" 8

Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 5

5) The traveler proposes to generically risk-inform LCO 3.0.3 using the risk assessment and management methodology contained in NUMARC 93-01, Section 11, similar to the precedents described in Section 2.4 of the traveler. Section 3.1.2 of the traveler provides operating experience to purport that the proposal will generically improve plant safety. The traveler did not describe how adequate DID or SM would be assured to justify the extended LCO 3.0.3 time frames in the submittal. The NRC staff uses the guidance in RG 1.177, "An Approach for Plant-Specific, Risk-Informed Decisionmaking: Technical Specifications" and RG 1.174 to evaluate risk-informed proposals regarding changes to TS completion times. DID and SM justifications are necessary elements of a risk informed submittal.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 5 Discussion As discussed in Section 3.1.3, the proposed change is not a risk-informed submittal in accordance with RG 1.174 or 1.177.

LIC-206, "Integrated Risk-Informed Decision-Making for Licensing Reviews," discusses the difference between risk-informed submittals, submittals that utilize risk insights, and deterministic submittals.

Using Figure 1, TSTF-585 is not a risk-informed application following RG 1.174 (a Type 3 change).

TSTF-585 is not a Type 2 change, in that the traveler does not contain PRA information or significant risk discussion.

TSTF-585 leverages already existing risk methods implementing 10 CFR 50.56(a)(4), which use Core Damage Frequency (CDF) and Large Early Release Frequency (LERF), but the traveler does not include any PRA calculations or significant risk discussion.

There is no reliance on plant-specific PRA models beyond those already implemented by licensees that are routinely inspected by the NRC. The traveler does not request NRC approval of those tools.

TSTF-585 is a Type 1 submittal, which "contains no PRA information and little to no risk discussion."

The TSTF is willing to repeat the October 25, 2022 MR workshop, if needed, to assist the NRC staff in evaluating the traveler.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 5 Defense-in-depth and safety margin are an aspect of RG 1.174 and 1.177 evaluations, which is not the correct guidance for evaluating the traveler. However:

- RG 1.160, "Monitoring the Effectiveness of Maintenance At Nuclear Power Plants,"

discusses demonstrating compliance with 10 CFR 50.65. It states that the Commission discussed defense-in-depth at various locations in approval of the MR and determined that the MR provides for continued emphasis on defense-in-depth.

- RG 1.174 states, "With sufficient safety margins, (1) the codes and standards or their alternatives approved for use by the NRC are met and (2) safety analysis acceptance criteria in the licensing basis (e.g., FSAR, supporting analyses) are met or proposed revisions provide sufficient margin to account for uncertainty in the analysis and data."

• The proposed change is only applicable if a TS LCO is not met. Therefore, it would be expected that codes and standards are not met, and safety analysis acceptance criteria are not met. Safety margin Is not a concept applicable to this change.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 5

a. Section 3.2.1 purports that a 6-hour preparation time is justified because the risk assessment and implementation of risk management actions (RMAs) can be accomplished within that time frame, and an anecdotal statement regarding conservative operator training in Section 3.2.1. The current LCO 3.0.3 total shutdown completion time requirement is extended by an additional 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />. The additional 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> of preparation time is allowed regardless of whether or not a risk assessment is successful or even performed. Thus, the additional 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> for the overall LCO 3.0.3 completion time are not dependent on any risk considerations, but are completely associated with deterministic considerations. However, these deterministic considerations, including preservation of adequate DID and reduction in SM (or impact on plant safety from extended operation in a condition of zero SM) are not described or evaluated in the submittal.

b. Section 3.2.4 purports that the extension of the preparation time to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is justified, given an acceptable risk assessment and implementation of RMAs, because the activities associated with preparing for a plant shutdown can be accomplished within the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The current LCO 3.0.3 total shutdown preparation time is extended by an additional 23 hours2.662037e-4 days <br />0.00639 hours <br />3.80291e-5 weeks <br />8.7515e-6 months <br /> if a risk assessment is successfully completed during the first six hours. The additional 23 hours2.662037e-4 days <br />0.00639 hours <br />3.80291e-5 weeks <br />8.7515e-6 months <br /> are purported to be supported by the risk-based consideration of utilizing the NUMARC 93-01, Section 11, maintenance risk assessment and management methodology. However, the deterministic considerations associated with a risk-informed justification, including preservation of adequate DID and reduction in SM (or impact on plant safety from extended operation in a condition of zero SM) are not described or evaluated in the submittal.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 5 Discussion Section 3.2.1 states that 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> is acceptable to perform the evaluation, not that the evaluation justifies 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

DID and Safety Margin are already discussed.

The 6-hour time to perform the risk assessment was a suggestion of the NRC staff in order to simplify the application of the requirements by providing time to perform the risk assessment and implement risk management actions before the decision of whether a 24-hour delay time is acceptable.

The current one-hour delay was chosen arbitrarily and has no safety basis.

Providing six hours instead of one hour is still an arbitrary period, but based on providing a reasonable time to perform analyses or take action before initiating a shutdown.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 9 9)

LCO 3.0.3 extended shutdown track should not apply when entered intentionally. As currently stated in the draft TSTF-585, it allows a 6-hour delay in commencing a shutdown for intentional entry, even though it says the 24-hour delay period doesnt apply.

Intentional entry should require the shutdown to begin immediately since the entry was planned, and the licensee presumably had appropriate time to prepare for the shutdown, including assessing risk and implementing RMAs.

Discussion In TSTF-565, the NRC approved a change to the LCO 3.0.3 Bases. The traveler removed the sentence, "It [i.e. LCO 3.0.3] is not intended to be used as an operational convenience that permits routine voluntary removal of redundant systems or components from service in lieu of other alternatives that would not result in redundant systems or components being inoperable." (emphasis added). The NRC accepted a change to the LCO 3.0.3 Bases to instead state, "Planned entry into LCO 3.0.3 should be avoided. If it is not practicable to avoid planned entry into LCO 3.0.3, plant risk should be assessed and managed in accordance with 10 CFR 50.65(a)(4), and the planned entry into LCO 3.0.3 should have less effect on plant safety than other practicable alternatives." This description is not altered in TSTF-585.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 9 The TSTF-565 justification continues to be applicable to the proposed LCO 3.0.3 change, in that the MR will be used to assess the risk of intentional entry, which should be avoided.

The current ability to intentionally enter LCO 3.0.3 is a necessary operational capability. Under many plant designs, necessary operations can result in a brief entry into LCO 3.0.3, such as venting piping common to two trains of a system or opening a door separating redundant components to move equipment. This capability should be retained to avoid initiating a plant shutdown, and is consistent with NRCs historical position:

- In 1979, NRC internal guidance (Accession No. 790807003) to the regions stated, ""[I]t should be noted that throughout the STS [Standard Technical Specifications], and typically in the custom technical specifications, the licensee is not prohibited from voluntarily entering action statements. We believe it is necessary and desirable to structure the technical specification to permit the operator to exercise judgment within the latitude permitted by Technical Specifications.

- In 1987, in a letter titled, "Intentional Entry into Technical Specification Limiting Condition for Operation 3.0.3," (Accession No. 8704300349), the NRC stated, "Region V recognizes that occasional entry into LCO 3.0.3 for surveillance or maintenance purposes may be appropriate."

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 6

6) Conditions that result in a loss of function, yet allow the extended action time, require more detailed justification, including DID measures and SMs, or dose consequences, if the extended action time can be applied. For example, the NRC disagrees with the TSTF conclusion that loss of function of emergency core cooling system (ECCS) does not require a direct shutdown path.

Discussion The term "loss of function" is not a black or white concept. Systems may be inoperable (which IS a black or white concept) while retaining significant functionality. Therefore, "loss of function" is not a useful term when discussing the appropriate actions when an LCO is not met and LCO 3.0.3 is entered.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 6 ECCS is an excellent example.

A licensee could enter LCO 3.0.3 because both low pressure ECCS pumps are inoperable. Those pumps are in standby at power, but in most designs they are needed for residual heat removal when shutdown. Requiring an immediate shutdown could be averse to safety even though it could be argued that a "loss of function" exists.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 8

8) There are no specified prerequisites for ensuring the risk assessments performed for LCO 3.0.3 are adequate to capture the configuration risk. Describe why the NUMARC 93-01 risk-assessment process is adequate to support TSTF-585.

Discussion The reasons why the NUMARC 93-01 risk assessment process is adequate to support TSTF-585 is described in Section 3.1.3 and 3.1.3.1 of the traveler justification.

At a public meeting between the TSTF and the NRC held on October 25, 2022, the TSTF and NRC discussed the use of the MR risk assessment for this application.

The TSTF is willing to hold another, similar public meeting if necessary.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 3

3) The wording of the proposed LCO 3.0.3 is not specific. The term acceptable, as it relates to continued plant operation should be defined. The model application should clearly define the risk criteria ("normal work control" core damage frequency (CDF) and large early release frequency (LERF)) that will be used to determine whether the additional time to shut down may be used.

Discussion The wording was chosen to be consistent with LCO 3.0.4, which states "determination of the acceptability."

The proposed LCO Bases state, "If the risk assessment determines that there is no more than a minimal increase in risk after implementation of risk management actions (i.e., the level determined acceptable during normal work control levels as discussed in Section 11 of NUMARC 93-01), then continuing operation for a limited time is acceptable."

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 7

7) As proposed, the traveler could potentially be applied after the time limit for a RICT is exceeded. Explain the interaction between TSTF-585 and TSTF-505. Demonstrate that its within the normal work controls risk thresholds.

Discussion Risk-Informed Completion Times only apply to Required Actions. There are no Required Actions with the RICT option that direct entry into LCO 3.0.3.

The TS provide default Actions when "Required Actions and associated Completion Times are not met," and those default Actions do not direct entering LCO 3.0.3.

Therefore, failing to complete the Required Actions within the RICT would not result in entering LCO 3.0.3.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 10

10) If the licensee does not have a reasonable expectation of being able to restore within the extended 24-hour period or of obtaining regulatory relief (e.g., an NOED), then they should begin the shutdown immediately. If the risk assessment is not performed, then shutdown should begin immediately.

Discussion In all TS Actions, the time allowed by the TS to take Actions is provided regardless of whether it is anticipated that the Action will be completed. As stated in Section 1.3, "Required Actions must be completed prior to the expiration of the specified Completion Time."

The TSTF's position is that regulatory requirements should not be based on intent or expectation. Applying "reasonable expectation" to a TS Action is contrary to a stable regulatory framework.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 2 2)

There are several mischaracterizations and sentences that are difficult to understand in the traveler.

a. The last sentence in the first paragraph of Section 2.3 states the proposed change requires a licensee to assess the risk significance of the degradation that led to entry. The overall plant risk, including the degradation, is assessed.

b. The last sentence of Section 3.0 is unclear.

c. The STS Bases state that a risk assessment addressing inoperable systems and components must be completed. The assessment must address the risk of the entire plant considering the inoperable structures, systems, and components (SSCs).

d. Some Westinghouse STS Bases markups are in a bad format, they look different than the other pages.

e. The last variation in the model evaluation is difficult to understand.

Discussion The listed issues can be addressed in the submitted traveler.

Regarding items a and c, the proposed LCO 3.0.3 Bases state, "The risk assessment must consider all inoperable equipment regardless of whether the equipment is included in the normal 10 CFR 50.65(a)(4) risk assessment scope." This is also consistent with Section 11 of NUMARC 93-01.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 4 4)

In Section 3.4.1, the traveler discusses the reason for allowing 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> if two trains of control room emergency filtration system (CREFS) are inoperable. The TS allows 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> if there is an inoperable boundary that results in two trains inoperable, but this does not apply to other conditions. The traveler does not discuss why the existing TS differentiate between inoperability due to boundary and other causes. The analysis is incomplete.

Control room heating, ventilation, and air conditioning (HVAC) TS should have its own shutdown path (up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) and not go to LCO 3.0.3.

Discussion The TSTF has provided a draft traveler to the NRC for comment, TSTF-604, "Revise Ventilation System Actions," which justifies a 24-hour Completion Time for two inoperable control room ventilation systems.

The discussion of control room ventilation will be removed from the traveler to avoid confusion.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Comment 11

11) The potential effect on reporting requirements should be addressed, i.e., the TS required shutdown commences upon entry into LCO 3.0.3, not at the end of the 24-hour CT.

Discussion There are no reporting requirements based on entry into LCO 3.0.3.

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Technical Specifications Task Force A Joint Owners Group Activity TSTF Next Steps

• The TSTF intends to revise the TSTF-585 draft considering the NRCs comments and to submit it for review.

• Does the NRC staff want the TSTF to arrange another workshop similar to the October 2022 workshop to discuss how the Maintenance Rule risk assessment tools can be used to assess the risk associated with remaining in LCO 3.0.3?

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Technical Specifications Task Force A Joint Owners Group Activity TSTF 26 Discussion