ML24137A289

Terrapower, LLC – Topical Report NAT-2965 Natrium Human Factors Engineering Program Plan and Methodologies Audit Plan

ML24137A289
Person / Time
Site:	99902100
Issue date:	05/28/2024
From:	Stephanie Devlin-Gill Office of Nuclear Reactor Regulation
To:
References
L-2023-TOP-0026
Download: ML24137A289 (1)

Text

TERRAPOWER, LLC -TOPICAL REPORT NAT-2965 NATRIUM HUMAN FACTORS ENGINEERING PROGRAM PLAN AND METHODOLOGIES AUDIT PLAN (EPID NO: L-2023-TOP-0026)

Applicant:

TerraPower, LLC Applicant Address:

15800 Northup Way, Bellevue, WA 98008 Plant Name:

Natrium Project No:

99902100

Background:

By letter dated April 26, 2023, TerraPower, LLC (TerraPower) submitted topical report (TR)

NAT-2965, Natrium Human Factors Engineering Program Plan and Methodologies Revision 0 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23116A225), to the U.S. Nuclear Regulatory Commission (NRC) staff. The TR describes the Natrium Human Factors Engineering (HFE) Program Plan (HFEPP), including related methodologies, and requests that the NRC staff review and approve to support referencing of the report in future licensing submittals. By email dated June 21, 2023, the NRC staff informed TerraPower that the TR provided sufficient information for the NRC staff to conduct a detailed technical review (ML23167A476).

Purpose:

The purpose of the audit is for the NRC staff to gain a more detailed understanding of the Natrium HFEPP and how the HFEPP will support or demonstrate compliance with NRC regulations as discussed below. In section 2.0 of the TR, Requirements and Technical Basis, TerraPower states that the HFEPP creates an HFE program that is compliant with the requirements of Title 10 of the Code of Federal Regulations (10 CFR) 50.34(f)(2)ii and 50.34(f)(2)iii. TerraPower states in the TR that the HFEPP considers relevant practices provided in NUREG-0711, Human Factors Engineering Program Review Model, Revision 3 (ML12324A013). A secondary purpose of the audit is to identify any information that will require docketing to support the NRC staffs safety evaluation.

Regulatory Audit Basis:

The basis for the NRC staff audit includes the following key regulations, guidance, and standards (which are also referenced by TerraPower in the TR):

10 CFR 50.34(f)(2)(ii), which states, in part, establish a program, to begin during construction and follow into operation, for integrating and expanding current efforts to improve plant procedures. The scope of the program shall include emergency procedures, reliability analyses, human factors engineering, crisis management, operator training 10 CFR 50.34(f)(2)(iii), which states, in part, provide, for Commission review, a control room design that reflects state-of-the-art human factor principles prior to committing to fabrication or revision of fabricated control room panels and layouts.

NUREG-0700, Human-System Interface Design Review Guidelines, Revision 3 (ML20162A214)

NUREG-0711, Human Factors Engineering Program Review Model, Revision 3 NUREG-1764, Guidance for the Review of Changes to Human Actions, Revision 1 (ML072640413)

Regulatory Audit Scope:

The regulatory audit will follow the guidance in NRR Office Instruction LIC-111 Regulatory Audits, Revision 1 (ML19226A274) and focus on information provided by TerraPower in the electronic reading room (ERR).

Information and Other Material Necessary for the Regulatory Audit:

The NRC staff requests that TerraPower make available the information or experts necessary to respond to the audit questions included in the enclosure. These questions relate to the HFE elements described by NUREG-0711 and the associated criteria contained within that guidance.

Team Assignments:

Jesse Seymour Senior Reactor Engineer (Examiner), Audit Lead Stephanie Devlin-Gill Senior Project Manager, Audit Manager Logistics:

Entrance Meeting June 13, 2024, 2:30 PM Exit Meeting July 10, 2024, 4:00 PM Audit meetings will take place in a virtual format, using Microsoft Teams or another similar platform. Audit meetings will be scheduled on an as-needed basis after the entrance meeting and once the NRC staff has had the opportunity to review any documents placed in the online reference portal. The audit will begin on June 13, 2024, and continue as necessary, with activities occurring intermittently during the audit period. The audit period may be reduced or extended, depending on the progress made by the NRC staff and TerraPower in addressing audit questions.

Special Requests:

The NRC staff requests that TerraPower ensure that their technical staff are available to answer questions during the audit. The NRC staff also requests that TerraPower provide access to supporting documents via the TerraPower ERR.

Deliverables:

At the completion of the audit, the audit team will issue an audit summary within 90 days after the exit meeting but will strive for a shorter duration. The audit summary will be declared and entered as an official agency record in ADAMS and be made available for public viewing through the Publicly Available Records component of ADAMS.

If you have questions about this audit, please contact me at 301-415-5301 or Stephanie.Devlin-Gill@nrc.gov.

Sincerely,

/RA/

Stephanie Devlin-Gill, Senior Project Manager Advanced Reactors Licensing Branch 1 Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation Project No.: 99902100

Enclosure:

As stated cc: TerraPower Natrium via GovDelivery

Package: ML24137A288 Public: ML24137A289 NRR-106 OFFICE NRR/DANU/UAL1:PM NRR/DANU/UAL1:LA NRR/DRO/IOLB:BC NAME SDevlin-Gill DGreene LNist DATE 05/01/2024 05/02/2024 05/03/2024 OFFICE NRR/DANU/UAL1:BC NRR/DANU/UAL1:PM NAME JBorromeo SDevlin-Gill DATE 05/20/2024 05/21/2024

Enclosure Topical Report NAT-2965 Audit Topics TerraPower states in the topical report that the Natrium Human Factors Engineering Program Plan considers relevant practices provided in NUREG-0711, Human Factors Engineering Program Review Model, Revision 3 (ML12324A013). The criteria referenced in this Enclosure are contained in NUREG-0711.

1. Topical Report (TR) Section 1, Introduction

a. Criterion 2.4.1(2): The design assumptions and constraints of the HFE program (i.e.,

aspects of the design that are inputs to the HFE program) are not described. The NRC staff request that TerraPower identify these design assumptions and constraints.

b. Criterion 2.4.1(3): The duration of the HFE program is not described. The NRC staff request that TerraPower clarify whether the HFE program will be in effect from the start of the design cycle through completion of the initial plant startup test program.

c. Criterion 2.4.1(4): The Energy Island (EI) is not addressed within the programmatic scope discussion (i.e., only a Nuclear Island (NI) control room is discussed). The NRC staff request that TerraPower clarify whether a separate control room will exist for the EI and whether it will be included within the scope of the HFEPP.

2. Criterion 2.4.1(6): Section 5.4, Staffing, of the TR describes that a staffing analysis process systematically determines the minimum staff complement. However, the TR does not include discussion of the Shift Technical Advisor (STA) role. The NRC staff request that TerraPower clarify whether the HFEPP is intended to be utilized in conjunction with a future justification for omission of the STA from the staffing model.

3. Criterion 2.4.2(2): Section 4.0, Human Factors Engineering Organization, of the TR provides a description of the HFE organization. However, details related to the organizational relationships, reporting relationships, and lines of communication associated with this team are unclear. The NRC staff requests that TerraPower clarify how the HFE team will have the authority and appropriate organizational placement to assure that its areas of responsibility can be completed, to identify problems in establishing the overall HFE plan, and to control further processing, delivery, installation, or use of HFE products until any nonconformances, deficiencies, or unsatisfactory conditions have been adequately resolved.

4. Criterion 2.4.2(3): Section 4.1.1, Roles, of the TR describes the roles and qualifications of the HFE team and states that this definition of roles is based on NUREG-0711. However, the description provided in the HFEPP does not fully conform to the guidance of NUREG-0711 in this area and clarification is needed regarding how the HFEPP addresses the following aspects of team roles and qualifications from the NUREG-0711 Appendix, Composition of the HFE Design Team:

o The typical contribution of Nuclear Engineering to provide knowledge of the processes involved in controlling reactivity and generating power.

o The minimum qualifications of Instrumentation and Control (I&C) Engineering to have familiarity with the theory and practice of software quality assurance and control, and the typical contribution to provide input to software quality assurance programs.

o The minimum qualification of Architect Engineering to have 4 years of experience in the design of power plant control rooms.

o The minimum qualifications of Computer System Engineering, including degree and experience requirements.

o The minimum qualifications of Plant Procedure Development to have 4 years of experience in developing procedures for nuclear power plants, and the expected typical contributions of the position.

o The minimum qualifications of Personnel Training to have 4 years of experience in developing personnel training programs for power plants and experience in applying the systems approach to training, in addition to the expected typical contributions to develop content and format of personnel training programs for licensed and non-licensed plant personnel and to coordinate training issues arising from activities.

5. TR Section 4.1.2, Responsibilities

a. Criterion 2.4.2(4): The NRC staff requests TerraPower further describe assignments of tasks to personnel, such as assignments of individual core team members and extended team members for various tasks and within HFE program elements.

b. Criterion 2.4.3(1): The NRC staff requests TerraPower also identify the process through which the team will execute its responsibilities, including procedures for the following:

o assigning HFE activities to individual team members o governing the internal management of the team o making decisions on managing the HFE program o making HFE design decisions o controlling changes in design of equipment o reviewing of HFE products

6. Criterion 2.4.3(5): The TR describes HFE Implementation Plans (IPs) that will be used to subsequently develop Results Summary Reports (RSRs). However, procedures for the retention of HFE documentation items (such as RSRs and their supporting materials) and for making them available to the NRC staff for review are not described within the TR. The NRC staff request that TerraPower make these procedures (or a summary of their scope and content) available.

7. Criterion 2.4.3(6): The TR does not discuss the how the Natrium HFE program will be applied to contractors and subcontractors that are engaged in HFE-related work. The NRC staff requests TerraPower clarify how HFE requirements will be included in contracts and subcontracts that contribute to the HFE program, how contractor and subcontractor compliance with HFE requirements will be verified, and what milestones and the methods will be used for this verification.

8. Criterion 2.4.4(2): In section 8.2, Criteria for Prioritizing Human Factors Engineering Issues and Human Engineering Discrepancies, of the TR, TerraPower discusses the methodology for prioritizing HFE issues and Human Engineering Discrepancies (HEDs). However, the TR does not appear to specify that those HEDs categorized at Priority 1 (i.e., highest) and Priority 2 (high) must be resolved, as well as when such HEDs must be resolved by during the design lifecycle and licensing process. The NRC staff request that TerraPower clarify how the resolution of Priority 1 and 2 HEDs will be ensured by the HFE program.

9. Section 5.1, Operating Experience Review

a. Criterion 3.4.1(2): The TR does not appear to address the consideration of relevant HFE issues from NUREG/CR-6400, Human Factors Engineering (HFE) Insights for Advanced Reactors Based Upon Operating Experience, (ML063480112) (e.g., generic safety issues, Three Mile Island (TMI) issues, NRC generic letters and information notices, etc.) within the Operating Experience Review (OER) process scope. The NRC staff requests TerraPower clarify how the information in NUREG/CR-6400, where appropriate, is considered within the OER process.

b. Criterion 3.4.2(1): The TR does not discuss the administrative procedures for evaluating operating, design, and construction experience, and for ensuring that applicable

important industry experiences will be provided in a timely manner to those designing and constructing the plant. The NRC staff request that TerraPower provide details regarding how the OER process will account for evaluation of operating experience.

c. Criterion 3.4.2(4): The TR does not describe how operating experience issues determined to be relevant to the design, but not yet addressed, will be documented within an issue-tracking system. The NRC staff requests TerraPower describe the mechanism by which this tracking will be accomplished.

10. Criterion 4.4(2): TR Section 5.3, Allocation of Function, and Appendix A, Human Factors Engineering Allocation of Function and Task Grading Methodology, describe the Allocation of Function (AOF) process. However, the TR does not appear to discuss whether the function allocation will be performed iteratively to keep it current throughout the facility lifecycle. The NRC staff request that TerraPower clarify how the AOF process will maintain the function allocation current.

11. Criterion 5.4(1): In Section B.1.2, Scope, of TR Appendix B, Human Factors Engineering Task Analysis and Human-System Interface Design Methodology, TerraPower states that the task analysis (TA) process addresses human interactions with NI plant systems.

However, it is not clear whether the TA and human-system interface (HSI) design HFE elements will be applied within the scope of EI functions as well. The NRC staff request that TerraPower clarify whether the TR addresses any EI tasks that may be important to plant safety during maintenance, tests, inspections, and surveillances, in addition to those EI tasks with potential concerns for personnel safety.

12. Criterion 6.4(2): TR Section 5.4, Staffing, and Appendix C, Human Factors Engineering Staffing Analysis Plan, describe the staffing analysis process. However, the TR does not address the regulatory requirements of 10 CFR 50.54(k), 50.54(l), and 50.54(m) for licensed operator staffing. Additionally, the TR does not describe how it is intended to address the Shift Technical Advisor (STA) role. The NRC staff request that TerraPower clarify both how 50.54(k) through (m) and the STA role will be addressed by the TR.

13. Criteria 8.4.3(1)-(5): The TR references the development and application of an HFE style guide. However, this style guide was not included in conjunction with the TR. The NRC staff request that TerraPower make the HFE style guide available for the NRC staff review in TerraPowers electronic reading room.

14. Criterion 8.4.4.1(7): The TR does not address the change process that is expected to be used for human-system interfaces (HSIs) in the operating plant. The NRC staff request that TerraPower describe how, in the operating plant, HSIs will be modified and updated, temporary HSI changes will be made, and personnel-defined HSIs will be created.

15. Criteria 8.4.4.2(1-3), (5-7), and (10-11): The TR does not appear to address the post-Three Mile Island (TMI) HSI inventory requirements of 10 CFR 50.34(f)(2)(iv), (v), (xi), (xvii), (xviii),

(xix), (xxvi), and (xxvii). The NRC staff request that TerraPower describe how the HSI design process of the HFEPP will ensure that the technologically relevant aspects of, at a minimum, the requirements summarized below are incorporated into the design:

o 50.34(f)(2)(iv) - Safety parameters display system o 50.34(f)(2)(v) - Status of safety systems o 50.34(f)(2)(xi) - Relief and safety valve indication o 50.34(f)(2)(xvii) - Containment related indications o 50.34(f)(2)(xviii) - Core cooling indications o 50.34(f)(2)(xix) - Instrumentation to monitor post-accident plant conditions o 50.34(f)(2)(xxvi) - Leakage control and detection o 50.34(f)(2)(xxvii) - Radiation monitoring

16. TR Section 5.7, Human-System Interface Design, and Appendix B describe the HSI design process.

a. Criterion 8.4.4.2(12): The TR does not appear to address how the HSI design process will account for the manual initiation of protective actions. The NRC staff request that TerraPower describe how it will be ensured that the HSI design will support the manual initiation of protective actions at the system level for those safety systems otherwise initiated automatically.

b. Criterion 8.4.4.2(13): The TR does not appear to cover how the HSI design process will address the manual initiation of systems associated with critical safety functions. The NRC staff request that TerraPower describe how the HSI design process will provide displays and controls in the control room for the manual actuation of critical safety function related systems, as well as for monitoring those parameters that support them.

Additionally, the NRC staff request that TerraPower describe how these displays and controls will be independent of, and different from, the normal instrumentation and controls otherwise used.

c. Criterion 8.4.4.5(2): The TR does not discuss how consistency will be achieved between those HSIs which are in the control room and those located outside of it. The NRC staff request that TerraPower discuss how it will be ensured that the HSIs of the Remote Shutdown Facility are consistent with those in the main control room.

d. Criterion 8.4.4.6(2): The TR also does not appear to address how consistency will be achieved between the design of HSIs for local control stations and those in the control room. The NRC staff requests TerraPower describe how HFE will be incorporated into the HSIs for local control stations to ensure both that they are consistent with those in the MCR and that personnel can easily understand and use the HSIs.

e. Criteria 8.4.5(1 - 4): The NRC staff note that an HSI design process should address considerations related to the following as they relate to HSI failures and degradations:

o the effects of HSI failures and degradations, o the alarms and indications needed for timely detection, o back-up systems to ensure that important personnel tasks can be completed, and o compensatory actions (as well as supporting procedures) to ensure that personnel effectively manage degradations and transitions to back-up systems.

While the TR addresses HSI failures during integrated system validation (ISV) activities (with identified issues generally being expected to be addressed via the iterative HFE process), the NRC staff also note that ISV only samples a subset of the possible I&C and HSI degradations that can impact personnel task performance. The NRC staff request that TerraPower clarify how the HFEPP processes for HSI design, TA, procedures, and HFE verification and validation (V&V) will, in aggregate, adequately address the impact of automation failures, I&C degradations, and HSI degradations on personal task performance.

17. TR Section 5.8, Procedure Development

a. Criterion 9.4(1): The TR does not describe the development of Generic Technical Guidelines (GTG) within the Procedure Development Plan (PDP). The NRC staff request that TerraPower clarify whether GTGs will be included in the procedure development program.

b. Criterion 9.4(4): The NRC staff request that TerraPower make the procedure writers guide available for review so that the adequacy of its content can be verified.

Specifically, confirmation is needed that procedures developed using this guide will contain the following elements, as applicable:

o title and identifying information o statement of applicability and purpose o prerequisites o precautions o important human actions o limitations and actions o acceptance criteria o check off lists, and o reference material

c. Criterion 9.4(8): The TR does not specifically address the plan for maintaining procedures and controlling updates. Clarification is needed regarding how the procedure plan will address both maintaining procedures and controlling procedure updates.

d. Criterion 9.4(9): The TR does not appear to describe the physical means by which personnel will access and use procedures, particularly during operational events.

However, the NRC staff noted that the TerraPower Human Factors Engineering Concept of Operations White Paper (ML23125A328), Section 3.5 Procedures, describes that the HSIs in the nuclear control room are designed to support use of computer-based procedures and, furthermore, that storage space is provided in the nuclear control room and remote shutdown facilities for hardcopy sets of operating procedures to support required operation. The NRC staff request that equivalent information to what is described in the white paper regarding procedure accessibility also be included within the TR or otherwise docketed.

18. TR Section 5.9, Training and Qualification Program Development

a. Criterion 10.4.1(2): Section 5.9 does not specify whether the categories of personnel covered by 10 CFR 50.120, Training and qualification of nuclear power plant personnel, are within the scope of the SAT-based training program. The NRC staff request that TerraPower clarify what specific categories of personnel that will be trained under the training program.

b. Criterion 10.4.2(1): The NRC staff note that the TR does not define organizational roles related to training program development. The NRC staff requests TerraPower describe the organizational roles for developing training requirements, training information sources, and training materials, as well as for implementing the training program.

c. Criterion 10.4.2(3): The TR does not appear to describe the facilities and resources that will be needed to satisfy the requirements of the training program. The NRC staff request that TerraPower define these necessary facilities and resources (e.g., a plant-referenced, full-scope simulator).

d. Criterion 10.4.4(2): The TR does not specify whether the simulation facility will conform to NRC Regulatory Guide (RG) 1.149, Nuclear Power Plant Simulation Facilities for use in Operator Training, License Examinations, and Applicant Experience Requirements, nor does the TR provide a description of either the simulator facility or the program for simulator training. The NRC staff requests TerraPower clarify whether the simulation facility will conform to RG 1.149 (including revision number), provide the details of the program for simulator training (including length of time), and describe the simulation facility as required by 10 CFR 55.45(b), Implementation--Administration, and 10 CFR 55.46, Simulation facilities.

19. Criterion 11.4.3.5.1(4): TR Section D.6.7.5, Situation Awareness, discusses how situational awareness (SA) is assessed during V&V activities. This section proposes to use traditional three-level SA measures in which, in part, participants answer SA questions during freezes

in scenarios. The NRC staff note that this type of SA measure was originally developed for measuring SA during tasks that demand quick reactions and predictions in rapidly changing aviation situations. The NRC staff request that TerraPower clarify the basis for the selected methodology and whether other SA measurement approaches were considered.

Additionally, while section D.6.7.5 discusses the use of Situation Awareness Global Assessment Technique, it is unclear whether this method will only be used during early validation work, or if it will also be applied during ISV. If other methodologies (e.g., Situation Awareness Rating Technique) will be utilized as well, then that should also be clarified.

20. Criterion 11.4.3.5.1(5): TR section D.6.7.6, Workload, states that cognitive workload will be measured during ISV using the National Aeronautics and Space Administrations Task Load Index. Please explain how cognitive workload will be assessed. Clarification is needed both regarding whether other cognitive workload measurement approaches were considered and the rationale for the selected assessment methodology.

21. TR Section 5.12, Human Performance Monitoring

a. Criterion 13.4(1): TR Section 5.12 does not address how the human performance monitoring program will address future plant changes/modifications and their potential effects on human performance. The scope of the performance monitoring program should provide assurance that personnel can use the design effectively, changes/modifications do not adversely affect human performance, important human actions can be accomplished within the criteria for time and performance, and that an acceptable level of performance is maintained. The NRC staff requests TerraPower describe how the human performance monitoring program will ensure that plant changes do not adversely affect human performance.

b. Criterion 13.4(2): It is unclear whether the human performance monitoring program will be in effect beginning at the initial loading of plant fuel.

A human performance monitoring program should, in part, begin at initial loading of the plants fuel and trend human performance after the plant is operational. The NRC staff request that TerraPower clarify at what point the human performance monitoring program will commence.

c. Criterion 13.4(3): TR Section 5.12 does not address whether the human performance monitoring program will be informed, in part, by deterministic safety insights or whether the plan will ensure that degradations and corrective actions are promptly addressed. A human performance monitoring program should be, in part, structured such that the monitoring of human actions is commensurate with their safety importance, while facilitating the detection and correction of degradations in performance before they compromise plant safety. Clarification is needed regrading whether the human performance plan will be informed by deterministic safety insights in conjunction with risk insights, as well as whether the plan will ensure that degradations and corrective actions are addressed in a timely manner.

d. Criterion 13.4(4): TR Section 5.12 does not discuss the potential use performance data approximations for circumstances in which plant or personnel performance under actual design basis conditions might not be readily measurable. Such approximations of performance data should be used when the performance of the plant or personnel under actual design basis conditions may not be readily measurable. The NRC staff request that TerraPower clarify whether it is intended to use approximations of performance data within such contexts.