ML23117A002
| ML23117A002 | |
| Person / Time | |
|---|---|
| Site: | 99902069, Hermes File:Kairos Power icon.png |
| Issue date: | 04/27/2023 |
| From: | David Petti Advisory Committee on Reactor Safeguards |
| To: | David Petti Advisory Committee on Reactor Safeguards |
| References | |
| Download: ML23117A002 (1) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS WASHINGTON, DC 20555 - 0001 April 27, 2023 MEMORANDUM TO:
David Petti, Lead Kairos Power Licensing Subcommittee Advisory Committee on Reactor Safeguards FROM:
David Petti, Member Advisory Committee on Reactor Safeguards
SUBJECT:
INPUT FOR ACRS REVIEW OF KAIROS NON-POWER REACTOR HERMES CONSTRUCTION PERMIT APPLICATION - SAFETY EVALUATION FOR CHAPTER 1, THE FACILITY In response to the Subcommittees request, I have reviewed the NRC staffs safety evaluation (SE) with no open items, and the associated section of the applicants Preliminary Safety Analysis Report (PSAR), for Chapter 1, The Facility. The following is my recommended course of action concerning further review of this chapter and the staffs associated safety evaluation.
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Background===
Chapter 1 provides an overview of the Hermes facility. It is a 35MWth test reactor that will be licensed under 10 CFR Part 50. The purpose of this non-power reactor is to test and demonstrate the key technologies, design features, and safety functions of the Kairos Power Fluoride SaltCooled High Temperature Reactor technology as well as its structures, systems, and components (SSCs). Kairos is pursuing a 104c license. The PSAR meets the guidance provided in NUREG-1537 for non-power reactors.
The reactor uses TRISO fueled pebbles in a molten salt, Flibe, coolant, resulting in a high temperature low pressure system with robust inherent safety characteristics. Functional containment is provided by TRISO fuel and the strong fission product retention capabilities of the Flibe. The design relies of passive heat removal and does not need an emergency core cooling system for decay heat removal.
Key inherent safety features include:
Functional containment provided by TRISO fuel and Flibe Primary heat transport system that operates at near atmospheric pressure All reactivity coefficients (fuel, moderate and coolant temperature) are negative.
Coolant void is negative and reflector coefficient is positive but small Reactor vessel and other safety related components are located within a seismically isolated structure
Shielding is used to minimize occupational exposure Ventilation systems are such that flow is from areas of no or low contamination zones to zones of higher concentration SE Summary This chapter of the SE describes the review procedures the staff used in the review of the Hermes construction permit application and the associated regulatory bases. At a minimum, a preliminary design needs only include the principal design criteria, the design bases, general facility arrangement, and approximate dimensions.
The staff identified ten ongoing R&D activities that are necessary to confirm the adequacy of the design of SSCs to resolve safety questions prior to the completion of construction. These are related to confirming fuel pebble behavior; high temperature material qualification and surveillance; oxidation of graphite; validation of computer codes; development of a fluidic diode; justification of thermodynamic and vapor pressure correlations used in source term analysis; development of process sensor technology for key reactor process variables; and development of reactor coolant chemical monitoring instrumentation. Kairos stated these activities will be completed before completion of construction. The staff is tracking these activities.
The staff reviewed Kairos assessment of relevant operating experience and specific design features related to the use of TRISO fuel, the use of Flibe coolant, the use of pebble bed reactor cores, and the use of graphite moderated reactors to facilities in the past. The staff confirmed that some of the characteristics of Hermes are novel and Kairos is using the historical operation experience to the extent practicable in the design.
The staff reviewed the principal safety considerations as described in Kairos Construction Permit (CP) application, as supplemented. Applicable standards and requirements have been met; relevant acceptance criteria have been satisfied for the preliminary design; there is reasonable assurance that the final design will confirm to the design bases with adequate margin for safety; there is reasonable assurance that the facility can be constructed in conformity with relevant regulations; radioactive releases from the facility are not likely to exceed guidelines of 10 CFR Part 100 and 10 CFR Part 20.
The staff also found that Kairos is acting in good faith in terms of its interactions with the Department of Energy for the disposition of high-level waste and spent nuclear fuel from the Hermes facility.
The staff finds that subject to certain condition the preliminary design and analysis of the Hermes facility, as described in the PSAR is sufficient and meets the applicable regulatory requirements and guidance for the issuance of a CP in accordance with 10 CFR Part 50.
Further technical information required to complete the safety analysis in support of operation can reasonably be left for later consideration in the Final Safety Analysis Report.
Concerns I did not identify any specific deficiencies in my review. Most of the details of the staff findings are found in other chapters of the SE.
Recommendation As lead reviewer for Hermes SE Chapter 1, I recommend no further action on the scope of this chapter.
References
- 1. USNRC, Draft Safety Evaluation for Hermes NonPower Reactor Preliminary Safety Analysis Report Chapter 1, February 7, 2023 (ML23065A010)
- 2. Kairos Power LLC, Submittal of the Preliminary Safety Analysis Report for the Kairos Power Fluoride Salt-Cooled, High Temperature Non-Power Reactor (Hermes), Revision 2, February 2023 (ML23055A672)
- 3. USNRC, NUREG-1537, Part 1, Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors, Format and Content, issued February 1996 (ML042430055)
- 4. USNRC, NUREG-1537, Part 2, Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors, Standard Review Plan and Acceptance Criteria, issued February 1996 (ML042430048)
April 27, 2023
SUBJECT:
INPUT FOR ACRS REVIEW OF KAIROS NON-POWER REACTOR HERMES CONSTRUCTION PERMIT APPLICATION - SAFETY EVALUATION FOR CHAPTER 1, THE FACILITY Package No: ML23117A000 Memo Accession No: ML23117A002 Publicly Available Y Sensitive N Viewing Rights:
NRC Users or ACRS Only or See Restricted distribution *via e-mail OFFICE ACRS/TSB*
SUNSI Review*
ACRS/TSB*
ACRS*
NAME WWang WWang LBurkhart (WWang for) DPetti DATE 4/27/2023 4/27/2023 4/27/2023 4/27/2023 OFFICIAL RECORD COPY