ML25105A030
| ML25105A030 | |
| Person / Time | |
|---|---|
| Site: | 99902069 |
| Issue date: | 05/16/2025 |
| From: | Cayetano Santos NRC/NRR/DANU/UAL1 |
| To: | Kairos Power |
| References | |
| Download: ML25105A030 (1) | |
Text
KAIROS POWER, LLC - AUDIT PLAN OF THE APPROACH TO ADDRESS LIMITATIONS AND CONDITIONS CONTAINED WITHIN SAFETY EVALUTIONS FOR FUELS TOPICAL REPORTS (EPID NO. L-2025-LRM-0057)
Applicant:
Kairos Power, LLC Applicant Address:
707 W. Tower Ave, Suite A Alameda, CA 94501 Plant Name(s) and Unit(s):
Kairos - Hermes Test Reactor Hermes 2 Test Reactor Facility Fluoride-Salt-Cooled, High-Temperature Reactor Project No.:
99902069
Background:
Kairos Power LLC (Kairos) began pre-application discussions with the U.S. Nuclear Regulatory Commission (NRC) staff on its proposed Kairos Power Fluoride-Salt-Cooled, High-Temperature Reactor (KP-FHR) in October 2018. In December of 2020, Kairos announced that the Hermes test reactor would be used to support future development of the KP-FHR. Kairos was issued a construction permit (CP) on December 14, 2023, for the Hermes 1 test reactor to be located at a site in Oak Ridge, Tennessee (Agencywide Documents Access and Management System (ADAMS) Accession No. Package ML23338A260). Kairos was issued two CPs on November 21, 2024, for the Hermes 2 test reactor facility located at an adjacent site (Package ML24324A019).
Since 2018 Kairos has submitted several topical reports (TR) and technical reports that apply to both the Hermes test reactors and the KP-FHR commercial power reactor. By letter dated December 18, 2019, Kairos submitted TR KP-TR-010-P, KP-FHR Fuel Performance Methodology (ML19352G704). This TR described a methodology for analyzing a tristructural isotopic (TRISO) coated fuel particle with a uranium oxycarbide (UCO) fuel kernel for the KP-FHR power and test reactors. The fuel performance methodology includes the manufacturing characteristics, material properties, physical models, and uncertainty analysis associated with modeling. By letter dated March 31, 2022, the NRC staff approved Revision 3 of KP-TR-010 subject to limitations and conditions contained within the associated NRC safety evaluation (Package ML21354A676). On May 5, 2022, Kairos submitted the approved version of Revision 3 of KP-TR-010-P-A (Package ML22125A275).
By letter dated June 30, 2020, Kairos submitted TR KP-TR-011-P, Fuel Qualification Methodology for the Kairos Power Fluoride Salt-Cooled High Temperature Reactor (KP-FHR),
(Package ML20182A829). This TR described the fuel qualification methodology for the KPFHR
2 power and test reactors. The KPFHR fuel consists of TRISO fuel particles embedded in a carbon matrix pebble. Kairos relies on the Electric Power Research Institute (EPRI) TR EPRI-AR-1(NP)-A, Uranium Oxycarbide (UCO) Tristructural Isotropic (TRISO)-Coated Particle Fuel Performance (Package ML20336A052) for qualification of the TRISO fuel particles, while KP-TR-011-P details the qualification of the fuel pebble. The methodology in KP-TR-011-P considers mechanical and structural performance as well as chemical, thermal, and irradiation effects on the fuel pebble. By letter dated March 2, 2023, the NRC staff approved Revision of 2 of KP-TR-011-P subject to limitations and conditions contained within the associated NRC safety evaluation (ML23048A326). On March 30, 2023, Kairos submitted the approved version of Revision 2 of KP-TR-011-P-A (Package ML23089A395).
Kairos plans to submit operating license (OL) applications for Hermes 1 and Hermes 2 in accordance with Part 50 of Title 10 of the Code of Federal Regulations (10 CFR), which will include the Final Safety Analysis Reports (FSARs). These TRs will be key references in the Hermes 1, Hermes 2, and KP-FHR FSARs and their use will require that the limitations and conditions contained within their respective safety evaluations are satisfied.
Purpose:
The purpose of this audit is for the NRC staff to gain a better understanding of Kairos approach to meet certain limitations and conditions specified in the NRC safety evaluations for KP-TR-010-P-A, KP-TR-011-P-A, and EPRI-AR-1(NP)-A. The audit is expected to facilitate a more effective and efficient review of Kairos upcoming OL applications for Hermes 1 and Hermes 2.
Regulatory Audit Basis:
The basis for the audit includes the regulatory requirements in paragraph (b)(4) of 10 CFR 50.34, Contents of applications; technical information. This requires that each application for an OL contain an FSAR that includes an analysis and evaluation of the design and performance of structures, systems, and components, of which performance of the fuel is a vital aspect, with the objective of evaluating the risk to public health and safety. The analysis and evaluation shall take into account any pertinent information developed since the submittal of the preliminary safety analysis report.
Regulatory Audit Scope:
The audit scope includes information that describes Kairos approach to meet the following limitations and conditions specified in the NRC safety evaluations for KP-TR-010-P-A, KP-TR-011-P-A, and EPRI-AR-1(NP)-A:
Limitation and Condition 1 in the NRC staffs safety evaluation (SE) for KP-TR-011-P-A states:
Future license applications for non-power KP-FHRs shall include justification of the applicability of this methodology during rapid reactor transient events.
Paragraph 8 in Section 3.5 of the NRC staffs SE for EPRI-AR-1(NP)-A states:
Particles from the AGR [Advanced Gas Reactor] tests fall within the ranges delineated by the statistical ranges laid out in the TR (specifically, the
3 specification ranges reflected in Table 5-5). As such, no limitation or condition need to be imposed on an applicant directly referencing this TR.
However, staff notes that this TR does not provide for the only set of parameters for acceptable TRISO performance, and that TRISO particles sharing many but not all the characteristics of the particles tested In the AGR program could easily be shown to perform adequately. An applicant could have particles exceeding boundary values in areas and continue to have acceptable performance, but an applicant-specific demonstration would need to be provided. Staff is receptive to reviewing applications that reference this TR with supplemental justification for limited discrepancies from the performance envelope described here, and review of that supplemental justification would be incorporated as part of any future licensing submittal.
Limitation and Condition 7 in the NRC staffs SE for KP-TR-010-P-A states:
The calculational framework may not be used to evaluate fuel performance during anticipated AOOs, DBAs, and BDBEs. In the present form of the methodology presented in the TR, justification for the temperature and irradiation conditions is provided only for quasi steady-state conditions, and additional information would need to be provided for the NRC staff to approve use of the methodology for AOOs, DBAs, and BDBEs.
Information and Other Material Necessary for the Regulatory Audit:
The NRC staff requests information describing how Kairos plans to meet the limitations and conditions listed above, which may include methodology updates, supporting experimental data, calculations, computer code validations, and other material, as applicable.
The NRC staff may request additional documents as needed.
Team Assignments:
Hakan Ozaltun Reactor System Engineer, Audit Lead Chris Van Wert Senior Technical Advisor Pravin Sawant Senior Nuclear Engineer Cayetano Santos Jr. Senior Project Manager Kenneth Geelhood Contractor Christine Goodson Contractor Additional audit team members may be added as needed.
Logistics:
Entrance Meeting:
June 2025, estimated and subject to change Exit Meeting:
August 2025, estimated and subject to change The NRC staff requests that all the documents in the audit scope be provided by Kairos on an online reference portal. An online reference portal, established by Kairos, would allow the NRC staff access to the technical information. Use of the online reference portal is acceptable provided that Kairos establishes measures to limit access to specific NRC staff (e.g., based on NRC e-mail addresses or the use of passwords which will only be assigned to the NRC staff
4 directly involved in the audit on a need-to-know basis) and to make the documents view-only (i.e., prevent NRC staff from saving, copying, downloading, or printing any documents). The conditions associated with the online reference portal must be maintained throughout the audit process. The NRC staff who should initially be granted access to the portal are listed in the Team Assignments section. The NRC project managers for the audit will provide Kairos with the names of additional NRC staff who should be granted access.
The NRC staff requests that Kairos make their technical staff and subject matter experts available to answer questions during the audit.
The audit will follow the guidance in the Office of Nuclear Reactor Regulation (NRR) Office Instruction LIC-111, Regulatory Audits (ML19226A274). Audit meetings will take place primarily in a virtual format, using Microsoft Teams. Audit meetings will be scheduled on an as-needed basis after the entrance meeting and once the NRC staff has reviewed the documents placed in the online reference portal. If a site visit is needed, review topics will be provided to Kairos and mutually agreeable dates will be established.
Special Requests:
None.
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 an earlier issuance. The audit summary will be declared and entered as an official agency record and be made publicly available for viewing through ADAMS.
References:
Title 10 of the Code of Federal Regulations NRR Office Instruction LIC-111, Regulatory Audits If you have questions about this audit, please contact me at 301-415-7270 or by email at Cayetano.Santos@nrc.gov.
Date: May 16, 2025 Cayetano Santos Jr., Sr. Project Manager Advanced Reactor Licensing Branch 1 Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation CAYETANO SANTOS Digitally signed by CAYETANO SANTOS Date: 2025.05.16 09:25:47 -04'00'