ML24193A214

Summary Report for the Regulatory Audit of the Kairos Power Hermes 2 Preliminary Safety Analysis Report - General Audit

ML24193A214
Person / Time
Site:	Hermes  File:Kairos Power icon.png
Issue date:	07/11/2024
From:	Michael Orenak NRC/NRR/DANU/UAL1
To:
References
EPID L-2023-CPS-0000
Download: ML24193A214 (50)

Text

SUMMARY

REPORT FOR THE REGULATORY AUDIT OF KAIROS POWER LLC HERMES 2

CONSTRUCTION PERMIT PRELIMINARY SAFETY ANALYSIS REPORT

GENERAL AUDIT

OCTOBER 2023 - JUNE 2024

1.0 BACKGROUND

AND PURPOSE

By letter dated July 14, 2023 (Agencywide Documents Access and Management System (ADAMS) Package Accession No. ML23195A121), Kairos Power LLC (Kairos) applied for a construction permits (CPs) under Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Domestic Licensing of Production and Utilization Facilities, for the Hermes 2 test reactor facility. The proposed facility contains two fluoride salt-cooled, high temperature test reactors with intermediate heat transfer loops and a common power generation system. The general audit plan was issued on October 3, 2023 (ML23268A446). This audit enabled the U.S.

Nuclear Regulatory Commission (NRC) staff (the staff) to gain a better understanding of the Hermes 2 CP application through review and discussion of underlying supporting documentation. Enhanced understanding and communications supported effective and efficient development of information needs.

2.0 AUDIT REGULATORY BASES

The bases for the audit are the regulations of 10 CFR 50.34, Contents of applications; technical information, paragraph (a), Preliminary safety analysis report, 10 CFR 100.10, Factors to be considered when evaluating sites, and 10 CFR 100.11, Determination of exclusion area, low population zone, and population center distance.

3.0 AUDIT OBJECTIVES

The primary objective of the audit was to enable a more effective and efficient review of the Hermes 2 preliminary safety analysis report (PSAR) through the staffs review of supporting documentation and discussion with Kairos.

4.0 AUDIT ACTIVITIES

The audit was conducted from October 2023 to June 2024, via the Kairos electronic reading room (ERR). The staff conducted the audit in accordance with the Office of Nuclear Reactor Regulation (NRR) Office Instruction LIC-111, Revision 1 Regulatory Audits, (ML19226A274).

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Members of the audit team, listed below, were selected based on their detailed knowledge of the subject. Audit team members included:

• Pravin Sawant, NRR (Senior Nuclear Engineer, Lead Technical Reviewer)

• Jason Schaperow, NRR (Senior Reactor Systems Engineer)

• Andrew Bielen, Office of Research (RES) (Senior Reactor Systems Engineer)

• Ben Adams, NRR (General Engineer)

• Michelle Hart, NRR (Senior Reactor Engineer)

• Clair Song, NRR (Mechanical Engineer)

• Alexander Chereskin, NRR (Materials Engineer)

• Alexandra Siwy, NRR (Senior Nuclear Engineer)

• Amitava Ghosh, NRR (Physical Scientist)

• Joe Ashcraft, NRR (Electronics Engineer)

• Calvin Chung, NRR (Electronics Engineer)

• Jenise Thompson, NRR (Geologist)

• Steve Jones, NRR (Senior Safety and Plant Systems Engineer)

• George Thomas, NRR (Senior Civil Engineer)

• Sarah Tabatabai, NRR (Geophysicist)

• Mike Orenak, NRR (Lead Project Manager)

• Matt Hiser, NRR (Senior Project Manager)

• Edward Helvenston, NRR (Project Manager)

• Brian Bettes, NRR (Project Manager)

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Prior to the audit, the audit team reviewed the PSAR and defined the range of topics in the audit plan to be addressed and focused on during the audit. The following table documents dates that the staff transmitted audit questions and when audit meetings were held:

Audit Questions (ADAMS Audit Meetings Accession No.)

October 13, 2023 (ML23296A220) October 4, 2023 (entrance meeting)

October 31, 2023 (ML23304A209) October 27, 2023 (structural design)

November 20, 2023 (ML23324A117) November 6, 2023 (operating life)

December 4, 2023 (ML23338A235) November 13, 2023 (instrumentation and control)

December 11, 2023 (ML23346A016) November 15, 2023 (seismic shear wave measurements)

January 2, 2024 (ML24002B139) November 28-29, 2023 (metallic materials crosswalk)

January 24, 2024 (ML24024A226) November 30, 2023 (nearby industrial facilities)

February 2, 2024 (ML24033A181) December 4, 2023 (human factors engineering)

February 12, 2024 (ML24043A217) December 5, 2023 (geology)

February 15, 2024 (ML24046A173) December 7, 2023 (materials and component replacement)

February 26, 2024 (ML24057A387) December 12, 2023 (instrumentation and control)

December 15, 2023 (structural design)

December 19, 2023 (multiple subjects)

December 19, 2023 (control room hazards, cranes and rigging)

January 3, 2024 (steam line breaks, load combinations and fatigue analyses)

January 4, 2024 (steam line breaks)

January 8, 2024 (accident analyses)

January 12, 2024 (irradiation of reactor vessel)

January 12, 2024 (geology)

January 16, 2024 (instrumentation and control)

January 17, 2024 (accident analyses)

January 19, 2024 (heat transport systems)

January 22, 2024 (instrumentation and control)

January 23, 2024 (thermal embrittlement)

January 25, 2024 (effective areas for aircraft impact)

February 1, 2024 (accident analyses)

February 8, 2024 (rupture disks)

February 21, 2024 (rupture disks and intermediate heat transfer system (IHTS))

February 28, 2024 (instrumentation and control)

March 6, 2024 (rupture disks and IHTS)

March 21, 2024 (rupture disks and IHTS)

April 3, 2024 (spent fuel pool storage racks)

May 2, 2024 (rupture disks and IHTS)

May 7, 2024 (rupture disks and IHTS)

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The staff reviewed the following documents via the ERR:

o Chapter 2 Data Report of Geotechnical Exploration K-33 Site Additional discussion of Boring B6 o Chapter 3 Hermes Reactor Building System Design Description o Chapter 4 Graphite Hermes 2 CPA Crosswalk Dec 2023 Metallics Hermes 2 CPA Crosswalk Dec 2023 Hermes Reactor Vessel Internals System Requirements Document Hermes Reactor Vesel System Requirements Document Hermes Reactor Vessel Support System Requirements Document Hermes Reactor Core System Design Description Hermes Reactivity Control and Shutdown System Design Description Hermes Reactor Vessel Internals System Design Description Hermes Reactor Vessel System Design Description Hermes Reactor Vessel Support System Design Description o Chapter 5 Kairos internal memo, BeNaF properties from open literature sources Hermes 2 Primary Heat Transport System Requirements Document Hermes 2 Intermediate Heat Transport System Requirements Document Hermes 2 Primary Heat Transport System Design Description Hermes 2 Intermediate Heat Transport System Design Description Hermes Primary Salt Pump System Design Description Briggs, R. B., 1963, Molten Salt Reactor Program Semiannual Progress Report for Period Ending July 31, 1963, ORNL-3529, Oak Ridge National Laboratory, Oak Ridge, Tennessee.

Draft Memo, A Qualitative Comparison Study of Construction Rules for Rupture Disks within ASME Section III, Division 5 and Section VIII, Division 2 Rupture Disk Design Code Justification o Chapter 6 Hermes Decay Heat Removal System Design Description o Chapter 7 Hermes Instrumentation, Controls & Electrical Description and Architecture o Chapter 9 Chemistry Control System Requirements Document Inert Gas System Requirements Document Inventory Management System Requirements Document Hermes Pebble Handling and Storage System Design Description Hermes Reactor Thermal Management System Design Description Hermes Chemistry Control System Design Description Hermes Inert Gas System Design Description Hermes Tritium Management System Design Description Hermes Inventory Management System Design Description

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o Chapter 13 Tritium Inventory and Release Calculation Methodology for the Maximum Hypothetical Accident and Postulated Events Applicability of the Maximum Hypothetical Accident to Hermes 2 Applicability of HER-EP-RPT-000-0005 to Hermes 2 Expected changes to QRA for Hermes 2 Adaptation of the Hermes Safety Case Documentation for Hermes 2 Thermal Fluids Phenomena Identification and Ranking Table

5.0

SUMMARY

OF AUDIT OUTCOME

The staffs audit focused on the review of supporting documents associated with the topics identified in the audit plan and subsequently transmitted questions. The staff reviewed information through the Kairos ERR and held discussions with Kairos staff to understand and resolve questions. In many cases, Kairos updated the Hermes PSAR to resolve items discussed in the audit. Gaining access to underlying documentation and engaging in audit discussions about various aspects of the Hermes 2 design facilitated the staffs understanding of the Hermes 2 CP application and aided in assessing the safety of the proposed test reactors. The tables below reproduce the transmitted audit questions and summarize the resolution of the questions.

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6.0 EXIT BRIEFING The staff conducted an audit closeout meeting on June 6, 2024. At the closeout meeting, the staff reiterated the purpose of the audit and discussed their activities.

7.0 ADDITIONAL INFORMATION RESULTING FROM AUDIT Three RCIs (ML24135A257 and ML24135A257) were generated as a result of this audit. Kairos submitted two documents describing the Hermes 1 docketed information that is applicable to Hermes 2 (ML23300A141 and ML23300A144). In addition, Kairos provided supplemental information and voluntarily updated portions of the Hermes 2 PSAR ( ML24138A211, ML24136A253, ML24073A317, ML24072A297, ML24039A189, ML24026A299, ML24025C685, ML24011A290, ML24009A247, ML24003A765, ML23356A078, ML23355A161, ML23355A192, and ML23349A147). PSAR updates were captured in aggregate though PSAR Revision 1, which included an updated version of KP-TR-022 (ML24144A090).

8.0 OPEN ITEMS AND PROPOSED CLOSURE PATHS

Not applicable. There were no deviations from the audit plan.

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SUMMARY

REPORT FOR THE REGULATORY GENERAL AUDIT OF KAIROS POWER LLC HERMES 2 CONSTRUCTION PERMIT PRELIMINARY SAFETY ANALYSIS REPORT DATED: JULY 11, 2024

ADAMS Accession No. ML24193A214 *concurred by email OFFICE PM: NRR/DANU/UAL1 LA: NRR/DANU/UAL1 BC: NRR/DEX/EXHB NAME MOrenak DGreene (SLent for) BHayes*

DATE 6/17/2024 6/24/2024 7/09/2024 OFFICE BC: NRR/DEX/EICB BC: NRR/DEX/ESEB BC: NRR/DANU/UTB2 NAME FSacko ITseng CdeMessieres*

DATE 7/03/2024 7/08/2024 07/10/2024 OFFICE BC: NRR/DANU/UAL1 PM: NRR/DANU/UAL1 NAME JBorromeo* MOrenak DATE 7/09/2024 7/11/2024