ML24051A065

Digital I&C LAR RAIs Re HFE (Email)

ML24051A065
Person / Time
Site:	Limerick
Issue date:	02/16/2024
From:	Marshall M Plant Licensing Branch 1
To:	Mascitelli F, Rickey A Constellation Energy Generation, Constellation Nuclear
Sreenivas V, NRR/DORL/LPLI, 415-2597
References
EPID L-2022-LLA-0140
Download: ML24051A065 (1)

Text

From:

Michael Marshall To:

[Licensee] Frank Mascitelli (Constellation Nuclear); Rickey, Ashley:(Constellation Nuclear)

Cc:

Demetrius Murray; Hipo Gonzalez

Subject:

Limerick Generating Station, Units 1 and 2 - Request for Additional Information Regarding Limerick Digital Instrumentation and Controls License amendment Request (EPID L-2022-LLA-0140)

Date:

Friday, February 16, 2024 10:37:00 AM Hello Frank and Ashley, By letter dated September 26, 2022 (Agencywide Documents Access and Management System Accession No. ML22269A569; non-public), as supplemented by letters dated August 12, 2022 (ML22224A149), November 29, 2022 (ML22333A817),

February 8, 2023 (ML23039A141), February 15, 2023 (ML23046A266), March 30, 2023 (ML23089A324), April 5, 2023 (ML23095A223), June 26, 2023 (ML23177A224),

July 31, 2023 (ML23212B236), September 12, 2023 (ML23255A095), October 30, 2023 (ML23303A223), November 21, 2023 (ML23325A206), and January 26, 2024 (ML24026A296), Constellation Energy Generation, LLC (Constellation; the licensee) submitted license amendment requests to replace the Limerick Generating Station, Units 1 and 2 (Limerick) existing safety-related analog control systems with a single digital control system called plant protection system. The supplement dated September 12, 2023 replaced in its entirety the original license amendment requests dated September 26, 2023. The licensee replaced the original submittal, because it had mistakenly included proprietary information in the non-proprietary parts of the requests. The U.S. Nuclear Regulatory Commission (NRC) staff made all of the original submittal non-public. With the exceptions noted by the licensee in its letter dated September 26, 2023, the content of the replacement and the original are the same.

The proposed amendment requests would change both the design and technical specifications to permit the use of a new single digital instrumentation and controls system to replace analog instrumentation of reactor protection system, analog nuclear steam supply shutoff system, emergency core cooling system, reactor core isolation cooling system, and end-of-cycle recirculation pump trip at Limerick. In addition, the proposed amendments would change the classification of the redundant reactivity control system from safety-related to non-safety-related, eliminate the automatic redundant reactivity control system feedwater runback function, eliminate the automatic isolation function for the turbine enclosure main steam line tunnel temperature high indication, eliminate several surveillance requirements, and allow the use of automated operator aids (or automated controls) from main control room.

The NRC staff has reviewed the information provided in the license amendment request and has determined that additional information is needed to complete our review. This request for additional information (RAI) was discussed with Constellation on February 15, 2024. Constellations response to the RAIs shall be provided to the NRC within 30 days of the date of this email.

RAIs 1 to 4 were provided to Constellation in a separate email dated January 26, 2024. The NRCs review is ongoing, and additional RAIs, if any, will be provided in separate correspondence.

RAIs

5. In response to the requirements in Three Mile Island (TMI) Action Item I.D.1, the licensee for Limerick reviewed the plants control room design with consideration of human factors engineering (HFE) principles. The review of the control room was required to include the use of task analysis (i.e., TMI I.D.1.5.1.b(ii)). A task analysis should identify important human actions (IHAs).

In Section 6.8 of the HFE Program Plan, which was included with Constellations letters dated September 26, 2022 and September 12, 2023, the licensee states that the human reliability analysis (HRA) identifies IHAs that are within the scope of the analog to digital upgrade. Also, the licensee states that risk-IHAs were identified in Chapter 19 of the final safety analysis report. The licensee stated that it used the screening analysis described in NUREG-1764, Guidance for the Review of Changes to Human Actions, and considered the guidance in NUREG-0711, Human Factors Engineering Program Review Model, in the identification of IHAs. In Sections 2.0 and 5.4 of the Combined Results Summary Report (RSR),

which was included in Constellations letters dated September 26, 2022 and September 12, 2023, the licensee stated that IHA considered in a manner consistent with the guidance in NUREG-0711, where applicable. NUREG-0711 Section 7.1 indicates applicants should identify those human actions most important to safety via a combination of probabilistic and deterministic analyses, and then address them when conducting the HFE. The specific guidance used from NUREG-0711 is not specified.

The HFE Conceptual Verification RSR, which was included with Constellations letters dated February 9, 2023 and April 5, 2023, contains a list of manual operator actions impacted by the modification and included in the current licensing basis in Section 4.3.2.1 Table 3. Section 4.3.2.2 Table 4 provides a list of additional manual actions considered, but that were not part of the licensing basis.

These actions in Table 4 were identified as time sensitive actions. However, neither of these sections discusses whether there were any IHAs identified using probabilistic analyses. Additionally, Sections 4.3.2.1 and 4.3.2.2 do not state whether these manual actions met the criteria to be considered an IHA.

a. Please clarify which of the manual actions described in Sections 4.3.2.1 and 4.3.2.2 of the HFE Conceptual Verification RSR are identified as an important IHAs per the HFE Program Plan.

b. Please, identify the specific guidance (i.e., methods) used to identify the IHAs, including whether any probabilistic analyses were used. For example, if specific guidance from NUREG-0711 was used, please provide the sections of the document that were used.

6. In response to the requirements in TMI Action Item I.D.1, the licensee for Limerick

reviewed the plants control room design considering HFE principles. The review of the control room was required to include the use of task analysis (i.e., TMI I.D.1.5.1.b(ii)). A task analysis should identify IHAs. The Limerick Detailed Control Room Design Review (DCRDR) Program Plan (comparable to the Limerick HFE Program Plan) that was developed by the licensee in response to TMI I.D.1 included an operating experience review (OER) intended to discover human engineering shortcomings that have caused actual operating problems.

In Section 6.8 of the HFE Program Plan, the licensee states that the HRA identifies IHAs that are within the scope of the analog to digital upgrade. The licensee stated that it used the screening analysis described in NUREG-1764 and considered the guidance in NUREG-0711 in the identification of IHAs. In Sections 2.0 and 5.4 of the Combined RSR, which was included in Constellations letters dated September 26, 2022 and September 12, 2023, the licensee stated that IHA considered in a manner consistent with the guidance in NUREG-0711, where applicable. NUREG-0711, Section 7.1 indicates applicants should identify those human actions most important to safety via a combination of probabilistic and deterministic analyses, and then address them when conducting the HFE. The specific guidance used from NUREG-0711 is not specified.

In Section 6.4 of the HFE Program Plan, the licensee states that its OER methodology is based on review criteria in NUREG-0711 and guidance in Electric Power Research Institute (EPRI) Report 3002004310, Human Factors Guidance for Control Room and Digital Human-System Interface Design and Modification.

The specific guidance used from NUREG-0711 and EPRI Report 3002004310 is not specified.

In the Limerick Safety-Related Instrumentation and Control Upgrade HFE Preliminary Validation (PV) RSR, which was included in Constellations letters dated March 30, 2023 and June 26, 2023, the licensee states that there are deterministic actions that are identified as impacted or affected by the modification. Specifically, some actions that were performed locally in the plant are now performed through the upgraded system from digital controls in the control room. In Section 1 of the PV RSR, the licensee states that Constellation personnel identified credited manual operator actions (CMAs) in the Limerick licensing basis that are impacted the analog to digital upgrade at Limerick.

Section 7.1 of NUREG-0711 states, in part, applicants identify those human actions most important to safety via a combination of probabilistic and deterministic analyses, and then address them when conducting the HFE.

NUREG-0711, Section 7.4 states that applicants should identify deterministic IHAs from operator actions credited in the Limerick Final Safety Analysis Report and operator actions identified in the diversity and defense-in-depth coping analyses.

Section 3.4.1(5) of NUREG-0711 states, in part, that the applicants OER should identify IHAs in the predecessor plants or systems and determine whether they remain important in the applicants design.

a. Please clarify as to whether the CMAs are required as a part of any identified IHAs identified deterministically which are affected by the modification.

b. If there are, please describe the methodology used to screen the existing impacted actions as IHAs.

c. Please provide a discussion on how operating experience affected the relevance of IHA and the proposed modifications.

7. In response to the requirements in TMI Action Item I.D.1, the licensee for Limerick reviewed the plants control room design considering HFE principles. The review of the control room was required to include the use of function analysis (i.e., TMI I.D.1.5.1.b(ii)). The Limerick DCRDR Program Plan (comparable to Limerick HFE Program Plan) that was developed by the licensee in response to TMI I.D.1 included a function analysis that examined the required functions and functional sequences with respect to available staffing, technology, and other resources to determine how the functions may be executed.

In Section 4 of the Combined RSR and in Section 6.5 of the HFE Program Plan, the licensee states that an functional requirements analysis (FRA) and function allocation (FA) were performed and that the facilitys FRA and FA methodology was based upon principles described in NUREG-0711, EPRI report providing HFE guidance for control room design and modification, IEEE-1023, Recommended Practice for the Application of Human Factors Engineering to Systems, Equipment, and Facilities of Nuclear Power Generating Stations and Other Nuclear Facilities, providing recommendations for applying HFE, and an EPRI HFE training course. The specific guidance used from NUREG-0711 and the other documents is not specified.

In Section 4.1.2 of the Combined RSR, the licensee describes the methodology used for the FRA. This includes taking the current list of control room tasks and using subject matter experts to review and identify all tasks that will be impacted by the modification. This section of the document does not specify what changes were made for the high-level functions, nor did the document discuss what the specific changes were made to impacted tasks.

Section 4.4 of NUREG-0711 describes use of a structured, documented methodology reflecting HFE principles to perform FRA and FA, including describing the plants functional hierarchy, including, as appropriate: goals, functions, processes, and systems. Based on the information provided by Section 4.1.2 of the Combined RSR, a task analysis was performed to determine changes to the current list of control room tasks. There was no discussion about the plants functional hierarchy.

a. Please clarify if there are no changes to the plants functional hierarchy or

requirements for high-level functions due to the proposed modification. If there are changes, please provide the following details regarding the task analysis:

i. Please describe the functional hierarchy, such as determining goals, functions, processes, or systems.

ii. Please clarify whether high-level functions remain unchanged and if they are, please provide the technical basis for modifications.

iii. Please describe which functions differed for the new design or clarify that there are no differences.

iv. Please provide a list of requirements that should be identified for each high-level function that will be affected by the proposed modification, if applicable.

8. In response to the requirements in TMI Action Item I.D.1, the licensee for Limerick reviewed the plants control room design considering HFE principles. The review of the control room was required to include the use of function and task analysis (i.e.,

TMI I.D.1.5.1.b(ii)). The DCRDR Program Plan (comparable to HFE Program Plan) that was developed by the licensee in response to TMI I.D.1 included a function analysis that examined the required functions and functional sequences with respect to available staffing, technology, and other resources to determine how the functions may be executed and a task analysis that delineated system functions and the specific actions that needed to be taken to accomplish those functions.

For manual actions that the operator must perform correctly to safely operate the unit or maintain it in a safe condition, the necessary cognitive and physical needs of the operator should be met, including an evaluation of the overall cognitive and physical load on the operator during performance of these actions. This includes consideration of other operator responsibilities and their impact on operator performance. Part of HFE includes determining if the overall cognitive and physical load on the operator will impact their ability to take the necessary manual actions to safely operate the unit or maintain it in a safe condition.

The function analysis is performed to review the new reassignments since existing functions were reassigned as part of the modification. In Section 4 and Appendix A of the Combined RSR, there is no discussion of the acceptability of the aggregate of all functions allocated to the control room staff, nor on whether the functions interfered with each other. Section 4 of the Combined RSR and Section 6.5 of the HFE Program Plan, the licensee states that the FRA and FA methodology was based on the principles in NUREG-0711, EPRI report providing HFE guidance for control room design and modification, IEEE-1023 providing recommendations for applying HFE, and an EPRI HFE training course. The specific guidance used from NUREG-0711 is not specified.

One of the principles of NUREG-0711 relates to ensuring that the overall role of

personnel is evaluated by considering all personnel allocated functions in the aggregate to ensure that the operator is able to perform all required duties.

a. Please describe how the new or changed operator tasks resulting from the modification were considered in conjunction with existing tasks such that the complete set of operator tasks were considered in aggregate for their appropriateness.

b. Please describe how the new or changed aggregate tasks affects the overall role of personnel.

Best Regards, Michael L. Marshall, Jr.

Senior Project Manager Plant Licensing Branch 1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation 301-415-2871 Docket No. 50-352 and 50-353