ML24137A266

Kairos - Hermes 2 Docs - Preliminary Chapter 9 of Hermes 2 SE to ACRS

ML24137A266
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Site:	Hermes  File:Kairos Power icon.png
Issue date:	05/15/2024
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From: Cayetano Santos Sent: Wednesday, May 15, 2024 11:40 AM To: Weidong Wang; Larry Burkhart Cc: Michael Orenak; Matthew Hiser; Brian Bettes; Josh Borromeo

Subject:

Preliminary Chapter 9 of Hermes 2 SE to ACRS Attachments: Chapter 09 - Auxiliary Systems.pdf

Weidong,

Attached is another preliminary chapter (Chapter 9) from the safety evaluation (SE) for the Hermes 2 construction permit application. This chapter has been reviewed by branch chiefs and received a preliminary review by OGC. However, this cha pter is not final because it still needs to be reviewed by division management and receive the final OGC review. Thus, this preliminary chapter could change between now and the approved SE that will be sent to ACRS for formal review. I am sending this chapter in advance so that members can become familiar with the safety evaluation and begin preparing for the formal review.

Fifteen preliminary chapters were provided to you on March 14, April 4, April 22, April 23, and May 10, 2024. If possible, I will send the remaining preliminary chapters (5 and 13) to you piecemeal after they receive the preliminary OGC review for the second and third planned subcommittee meetings on June 4 and June 12, 2024.

Kairos Power submitted Revision 0 of the preliminary safety analysis report (PSAR) for Hermes 2 in July 2023. All preliminary SE chapters being sent to the ACRS refer to Revision 1 of the PSAR. Although Revision 1 of the PSAR has not been submitted, Kairos stated their intent to do so once all PSAR changes are known (i.e., the end of the technical review). The current list of docketed PSAR changes that will be incorporated into Revision 1 of the PSAR can be found in ADAMS and on the NRC public webpage at https://www.nrc.gov/reactors/non-power/new-facility-licensing/hermes2-kairos/documents.html.

The staff has taken a different approach toward the Hermes 2 SE considering that Hermes 1 and Hermes 2 CP applications have most of the same information. Due to these similarities, the staff leveraged the Hermes 1 SE to the extent possible for Hermes 2, using an incorporation by reference for many sections. The following description, taken from Chapter 1 of the Hermes 2 SE, discusses how the staffs review of Hermes 1 was applied to its review of the Hermes 2:

Use of Docketed Information

The staffs review of the Hermes 2 CP application was informed by the Hermes 1 CP application review. The Hermes 2 facility includes many SSCs that are identical to those that would be used in the Hermes 1 facility. Accordingly, large portions of the Hermes 1 PSAR are identical to the Hermes 2 PSAR. In the July 14, 2023, CP application submittal, Kairos highlighted the differences between the Hermes 1 and Hermes 2 PSARs in two ways. First, Kairos used blue font in the Hermes 2 PSAR to identify any modified or new text. Second, Kairos provided a summary of the information deleted from the Hermes 1 PSAR to generate the Hermes 2 PSAR (ML23195A132).

In addition, Kairos identified the docketed information and audit information from Hermes 1 that is applicable to the Hermes 2 CP application in two letters dated October 27, 2023 (ML23300A141 and ML22300A144). This information is considered docketed information for the Hermes 2 CP application and was used to inform the staffs review.

Format and Content of Hermes 2 Safety Evaluation Sections

Based on the consistencies between the Hermes 1 and Hermes 2 PSARs described above, the staff leveraged the Hermes 1 SE to the greatest extent possible to support its review of the Hermes 2 CP application. Accordingly, applicable contents of the Hermes 1 SE were incorporated by reference into this SE. To determine which Hermes 1 SE content could be incorporated by reference, the staff reviewed the differences between the Hermes 1 and Hermes 2 PSARs. Where the Hermes 2 PSAR only contained minor deviations (e.g., minimal or no effect on the NRC SE or editorial changes, as compared to the Hermes 1 PSAR), the staffs SE was largely limited to incorporating by reference applicable portions of the Hermes 1 SE. Similarly, where the Hermes 2 PSAR contained a limited number of significant but discrete changes, but was otherwise identical to the Hermes 1 PSAR, the staffs SE was likewise limited to an evaluation of the variances between the two PSARs. In this case, the balance of the staffs SE also incorporated by reference applicable portions of the Hermes 1 SE. Based on this approach, many of the Hermes 2 SE sections are organized using the following structure:

• Brief introduction summarizing the Hermes 2 PSAR content with a focus on any changes in comparison to the Hermes 1 PSAR.

• Regulatory evaluation section that, in most cases, incorporates by reference the regulations and guidance from the corresponding section of the Hermes 1 SE due to the similarities between the Hermes 1 and Hermes 2 facility designs.

• Technical evaluation that:

o Identifies the consistent and modified Hermes 2 PSAR information, as compared to the Hermes 1 PSAR.

o Incorporates by reference, as appropriate, content from the Hermes 1 SE for PSAR information that is consistent between Hermes 1 and Hermes 2.

o Evaluates the new design information and non-editorial changes (i.e.,

minor and/or few significant changes), as compared to the Hermes 1 SE.

The depth of the staff review provided for each change is dependent on the significance of that change.

• A full conclusion specific to the Hermes 2 review.

For Hermes 2 PSAR sections that contain entirely new information and/or several significant changes when compared to the Hermes 1 PSAR, the staff performed its evaluation without incorporation by reference from the Hermes 1 SE. One example of a section which reflects such an evaluation by the staff is Section 5.2, Intermediate Heat Transport System, of this SE related to the intermediate salt loops. These systems are not in the design of the Hermes 1 test reactor; therefore, they were not evaluated by the staff in its review of the Hermes 1 CP application. Accordingly, the staff evaluated this system without incorporation by reference of the Hermes 1 SE.

If you have any questions, please contact me, Michael Orenak, or Matt Hiser.

- Tanny Santos

Hearing Identifier: Kairos_Hermes2_CPDocs_Public Email Number: 17

Mail Envelope Properties (MW4PR09MB90103FCD02274FDC768B015DE5EC2)

Subject:

Preliminary Chapter 9 of Hermes 2 SE to ACRS Sent Date: 5/15/2024 11:39:57 AM Received Date: 5/15/2024 11:39:00 AM From: Cayetano Santos

Created By: Cayetano.Santos@nrc.gov

Recipients:

"Michael Orenak" <Michael.Orenak@nrc.gov>

Tracking Status: None "Matthew Hiser" <Matthew.Hiser@nrc.gov>

Tracking Status: None "Brian Bettes" <Brian.Bettes@nrc.gov>

Tracking Status: None "Josh Borromeo" <Joshua.Borromeo@nrc.gov>

Tracking Status: None "Weidong Wang" <Weidong.Wang@nrc.gov>

Tracking Status: None "Larry Burkhart" <Lawrence.Burkhart@nrc.gov>

Tracking Status: None

Post Office: MW4PR09MB9010.namprd09.prod.outlook.com

Files Size Date & Time MESSAGE 6029 5/15/2024 11:39:00 AM Chapter 09 - Auxiliary Systems.pdf 324821

Options Priority: Normal Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

THIS NRC STAFF DRAFT SE HAS BEEN PREPARED AND IS BEING RELEASED TO SUPPORT INTERACTIONS WITH THE ACRS. THIS DRAFT SE HAS NOT BEEN SUBJECT TO FULL NRC MANAGEMENT AND LEGAL REVIEWS AND APPROVALS, AND ITS CONTENTS SHOULD NOT BE INTERPRETED AS OFFICIAL AGENCY POSITIONS.

9 AUXILIARY SYSTEMS

The auxiliary systems of the Hermes 2 test reactor facility consist of the reactor coolant auxiliary systems (the chemistry control system (CCS), the inert gas system (IGS), the tritium management system (TMS), the inventory management system (IMS), and the reactor thermal management system (RTMS); the reactor building heating, ventilation and air conditioning system (RBHVAC); the pebble handling and storage system (PHSS); the fire protection systems; the communication system; facilities for possession and use of byproduct, source, and special nuclear material (SNM); the plant water systems (service water system, treated water system, component cooling water system (CCWS), chilled water system); other auxiliary systems (remote maintenance and inspection system, spent fuel cooling system (SFCS),

compressed air system, cranes and rigging, and auxiliary site services); and the power generation system (PGS).

This chapter of the Hermes 2 construction permit safety evaluation (SE) describes the technical review and evaluation by the U.S. Nuclear Regulatory Commission (NRC) staff (the staff) of the preliminary design of the Kairos Power LLC (Kairos) Hermes 2 test reactor facility as presented in Chapter 9, Auxiliary Systems, of the Hermes 2 preliminary safety analysis report (PSAR),

Revision 1. The staff reviewed Hermes 2 PSAR Chapter 9 against the applicable regulatory requirements using regulatory guidance and standards to assess the sufficiency of the preliminary information on the Hermes 2 auxiliary systems for the issuance of CPs in accordance with Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Domestic Licensing of Production and Utilization Facilities. The following sections of the SE describe the areas reviewed as specified in NUREG-1537, Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors, Part 2, Standard Review Plan and Acceptance Criteria, as appropriate.

The principal design criteria (PDC) for the facility structures, systems, and components (SSCs) are described in Section 3.1 of the PSAR. The PDC are based on the NRC approved Kairos Power Topical Report, KP-TR-003-NP-A, Principal Design Criteria for the Kairos Power Fluoride Salt-Cooled, High Temperature Reactor, Revision 1, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20167A174). Each of the sections below identify the applicable PDC for the system being evaluated.

9.1 Reactor Coolant Auxiliary Systems

The reactor coolant auxiliary systems are made up of five systems that provide support for the functionality and performance of the Flibe coolant. Each of the five systems is evaluated in a separate section below.

9.1.1 Chemistry Control System

9.1.1.1 Introduction

Section 9.1.1, Chemistry Control System, of the Hermes 2 PSAR describes the CCS as being used to monitor coolant chemistry in the reactor vessel system and primary heat transport system (PHTS) for compliance with Flibe specifications found in KP-TR-005-P-A, Reactor Coolant for the Kairos Power Fluoride Salt-Cooled High Temperature Reactor Topical Report, Revision 1 (ML20219A591). The CCS allows for offline analysis of Flibe chemistry and can remove and replace a sufficient amount of coolant to restore conformance with the Flibe specification via the IMS. The CCS does not perform any safety-related functions, nor is it credited to mitigate postulated events. Each Hermes 2 unit has its own CCS and there are no shared components between the units.

9.1.1.2 Regulatory Evaluation

The staff reviewed Section 9.1.1.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the CCS design between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.1.1.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.1.1.2 of the Hermes 1 SE.

9.1.1.3 Technical Evaluation

The staff reviewed Section 9.1.1 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.1.1, Chemistry Control System). The staff found that Section 9.1.1 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for the minor change evaluated below. The staff also verified that the Hermes 2 CCS design and functionality remain identical to Hermes 1. Based on these consistencies, this section incorporates by reference Section 9.1.1.3, Technical Evaluation, of the Hermes 1 SE.

9.1.1.3.1 Minor Change Compared to the Hermes 1 PSAR

The minor change in Hermes 2 PSAR Section 9.1.1, as compared to the information in Hermes 1 PSAR Section 9.1.1, is the following:

x Each unit has its own CCS and there are no components shared between the units.

The CCS does not perform safety-related functions. Additionally, each unit having its own CCS will prevent one failure in the system from affecting both units. Based on the above, the staff finds that having a CCS for each unit is acceptable.

On the basis of its review, the staff finds that the CCS design will conform with guidance in NUREG-1537, Part 2, Section 5.4, Primary Coolant Cleanup System, to monitor and maintain coolant purity in order to limit degradation of essential components in the primary system.

9.1.1.4 Conclusion

Based on staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the information in Hermes 2 PSAR Section 9.1.1 is sufficient and meets applicable guidance and regulatory requirements identified in this section for the issuance of CPs in accordance with 10 CFR 50.35, Issuance of construction permits, and 10 CFR 50.40, Common standards. The information provided gives the staff reasonable assurance that the CCS will not lead to radiation exposure or releases that exceed limits in 10 CFR Part 20, Standards for Protection Against Radiation, and that the CCS can support proposed technical specifications related to coolant chemistry.

Further information will be required before approving operation of the Hermes 2 CCS (e.g.,

basis of sampling location to provide a well-mixed and representative chemistry sample, ability of CCS to correct coolant chemistry within specified timeframes) and this information will be reviewed at the operating license (OL) stage.

9.1.2 Inert Gas System

9.1.2.1 Introduction

Section 9.1.2, Inert Gas System, of the Hermes 2 PSAR describes the IGS. The design functions of the IGS are to:

x Maintain an inert environment for components using argon x Provide inert gas purge flow x Remove impurities from cover gas x Provide transport of tritium for treatment x Provide reactor coolant motive force during filling and draining

The PSAR also states that the IGS does not perform any safety-related functions. Each Hermes 2 unit has its own IGS and there are no shared components between the units.

9.1.2.2 Regulatory Evaluation

The staff reviewed Section 9.1.2.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the IGS between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.1.2.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.1.2.2 of the Hermes 1 SE.

9.1.2.3 Technical Evaluation

The staff reviewed Section 9.1.2 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.1.2, Inert Gas System). The staff found that Section 9.1.2 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for the minor change evaluated below. The staff also verified that the Hermes 2 IGS design and functionality remain identical to Hermes 1. Based on these consistencies, this section incorporates by reference Section 9.1.2.3, Technical Evaluation, of the Hermes 1 SE.

9.1.2.3.1 Minor Change Compared to the Hermes 1 PSAR

The minor change in Hermes 2 PSAR Section 9.1.2, as compared to the information in Hermes 1 PSAR Section 9.1.2, is the following:

x Each unit has its own IGS and there are no components shared between the units.

The system does not perform safety-related functions. Additionally, each unit having its own IGS will prevent one failure in the system from affecting both units. Based on the above, the staff finds that having a IGS for each unit is acceptable.

On the basis of its review, the staff finds that the IGS will be consistent with 10 CFR 20.1406, Minimization of contamination, based on its preliminary design, as there are systems provided to remove radioactive material from the IGS if necessary, and because the IGS can be monitored for leaks which would allow for action to limit release of radioactivity. The staff will verify the capability to monitor activity and releases with the design details provided in the OL application. Additionally, the staff finds that the IGS will be designed consistent with the guidance in NUREG-1537, Part 2, Section 9.6, Cover Gas Control in Closed Primary Coolant Systems, to assess and maintain cover gas purity and meet any technical specification applicable to the IGS.

9.1.2.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the information in Hermes 2 PSAR Section 9.1.2 is sufficient and meets applicable guidance and regulatory requirements identified in this section for issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. The information provided gives the staff reasonable assurance that the IGS can meet its design functions and will not lead to radiation exposure or releases that exceed limits in 10 CFR Part 20. Further information as may be required to complete the review of the Hermes 2 IGS (e.g., limit on circulating activity in the cover gas, details for allowable impurities, leakage detection) and can reasonably be left for later consideration in the OL application since this information is not necessary for the review of a CP application.

9.1.3 Tritium Management System

9.1.3.1 Introduction

Section 9.1.3, Tritium Management System, of the Hermes 2 PSAR describes a preliminary design for the TMS, which monitors and removes tritium from the vapor spaces of the reactor coolant system, the intermediate heat transport system (IHTS), the heat rejection radiator (HRR) enclosure, and the reactor buildings during normal operation. PSAR Section 9.1.3 states that the systems do not perform safety-related functions. Each Hermes 2 unit has its own TMS and there are no shared components between the units.

9.1.3.2 Regulatory Evaluation

The staff reviewed Section 9.1.3.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the TMS design between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.1.3.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.1.3.2 of the Hermes 1 SE.

9.1.3.3 Technical Evaluation

The staff reviewed Section 9.1.3 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.1.3, Tritium Management System). The staff found that Section 9.1.3 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for a few minor and significant changes, which are evaluated below in Sections 9.1.3.3.1 and 9.1.3.3.2, respectively. The staff found that the following portions of Section 9.1.3 in the Hermes 2 PSAR contain information consistent with the Hermes 1 PSAR (e.g., minor or editorial changes only):

x Section 9.1.3.2, Design Bases x Section 9.1.3.3, System Evaluation x Section 9.1.3.4, Testing and Inspection x Section 9.1.3.5, References

Since the Hermes 2 system design and functionality largely remain identical, excepting the differences evaluated below, there are few changes to the TMS as described in Section 9.1.3 of the Hermes 2 PSAR when compared to Section 9.1.3 of the Hermes 1 PSAR. Based on these consistencies, this section incorporates by reference Section 9.1.3.3, Technical Evaluation, of the Hermes 1 SE.

9.1.3.3.1 Minor Changes Compared to the Hermes 1 PSAR

The minor change in Hermes 2 PSAR Section 9.1.3, as compared to the information in Hermes 1 PSAR Section 9.1.3 is the following:

x Each unit has its own TMS and there are no components shared between the units.

The TMS does not perform safety-related functions. Each unit having its own TMS without any shared components will prevent one failure in the system from affecting both units. Based on the above, the staff finds that having a TMS for each unit is acceptable.

9.1.3.3.2 Significant Change Compared to the Hermes 1 PSAR

The significant change contained in Section 9.1.3 of the Hermes 2 PSAR, as compared to Section 9.1.3 of the Hermes 1 PSAR, includes information regarding the following:

x The addition of two primary system functions to the TMS: tritium separation from argon in the IHTS cover gas and tritium separation from dry air in the HRR enclosure

These changes are identified in PSAR Section 9.1.3.1, Description.

The staff evaluated the sufficiency of this additional preliminary information on the Hermes 2 TMS using the guidance and acceptance criteria from NUREG-1537, Part 2, Section 9.7, Other Auxiliary Systems. Because the TMS does not perform safety-related functions, adding two locations in the plant for monitoring and removing tritium does not affect reactor safety and is appropriate considering the addition of the IHTS and the HRR to the Hermes 2 facility design, as compared to the Hermes 1 facility design. Based on the above, the staff finds that the addition of the two additional TMS primary functions is acceptable.

On the basis of its review, the staff finds that the level of detail provided regarding the Hermes 2 TMS demonstrates an adequate basis for a preliminary design and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.7, to prevent uncontrolled release of radioactivity, to limit potential radiation exposures to within 10 CFR Part 20 requirements, and for no function or malfunction of the TMS to interfere with or prevent safe shutdown of the reactor.

9.1.3.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the information on the TMS in Hermes 2 PSAR Section 9.1.3 is sufficient and meets applicable guidance and regulatory requirements identified in this section for issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. The staff concludes that the preliminary design features intended to minimize contamination, support eventual decommissioning, and control releases to the environment will help ensure compliance with 10 CFR Part 20.

9.1.4 Inventory Management System

9.1.4.1 Introduction

Section 9.1.4, Inventory Management System, of the Hermes 2 PSAR describes a preliminary design for the IMS, which adds and removes reactor coolant to maintain the desired level and volume within reactor-coolant-containing systems and components (e.g., reactor vessel, CCS).

Each Hermes 2 unit has its own IMS and there are no shared components between the units.

Hermes 2 PSAR Section 9.1.4 states that the system does not perform safety-related functions.

9.1.4.2 Regulatory Evaluation

The staff reviewed Section 9.1.4.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the IMS design between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.1.4.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.1.4.2 of the Hermes 1 SE.

9.1.4.3 Technical Evaluation

The staff reviewed Section 9.1.4 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.1.4, Inventory Management System). The staff found that Section 9.1.4 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for minor changes evaluated below. The staff also verified that the Hermes 2 IMS design and functionality remain identical to Hermes 1. Based on these consistencies, this section incorporates by reference Section 9.1.4.3, Technical Evaluation, of the Hermes 1 SE.

9.1.4.3.1 Minor Changes Compared to the Hermes 1 PSAR

The minor changes in Hermes 2 PSAR Section 9.1.4, as compared to the information in Hermes 1 PSAR Section 9.1.4, include the following:

x Each unit has its own IMS and there are no components shared between the units.

x A change in the system description to reflect that the Hermes 2 design includes an intermediate heat exchanger (IHX).

The IMS does not perform safety-related functions. Each unit having its own IMS will prevent one failure in the system from affecting both units. The addition of the IHX to the system description is appropriate due to the IHX being a new SSC in the Hermes 2 design that is filled with reactor coolant on the shell side by the IMS. Based on the above, the staff finds that each unit having its own IMS and that the identification the IHX as being filled by the IMS are acceptable.

On the basis of its review, the staff finds that the preliminary design of the IMS satisfies the applicable acceptance criteria in NUREG-1537, Part 2, Section 9.7, to prevent uncontrolled release of radioactivity and for no function or malfunction of the IMS to interfere with or prevent safe shutdown of the reactor.

9.1.4.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the information on the IMS in PSAR Section 9.1.4 is sufficient and meets the applicable guidance and regulatory requirements identified in this section for issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. The staff concludes that the preliminary design features intended to minimize contamination and support eventual decommissioning will comply with the requirements of 10 CFR 20.1406.

9.1.5 Reactor Thermal Management System

9.1.5.1 Introduction

Section 9.1.5, Reactor Thermal Management System, of the Hermes 2 PSAR describes a preliminary design for the RTMS which consists of two subsystems: the equipment and structural cooling subsystem (ESCS) and the reactor auxiliary heating system (RAHS). The purpose of the ESCS is to remove heat from SSCs in the reactor cavity to maintain the temperatures within operational limits. The purpose of the RAHS is to preheat the reactor vessel and to ensure Flibe in the vessel is maintained above a minimum operating temperature. Each Hermes 2 unit has its own RTMS and there are no shared components between the units.

Hermes 2 PSAR Section 9.1.5 states that the RTMS does not perform safety-related functions.

9.1.5.2 Regulatory Evaluation

The staff reviewed Section 9.1.5.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the RTMS design between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.1.5.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.1.5.2 of the Hermes 1 SE.

9.1.5.3 Technical Evaluation

The staff reviewed Section 9.1.5 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.1.5, Reactor Thermal Management System). The staff found that Section 9.1.5 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for the minor change evaluated below. The staff also verified that the Hermes 2 RTMS design and functionality remain identical to Hermes 1. Based on these consistencies, this section incorporates by reference Section 9.1.5.3, Technical Evaluation, of the Hermes 1 SE.

9.1.5.3.1 Minor Change Compared to the Hermes 1 PSAR

The minor change in Hermes 2 PSAR Section 9.1.5, as compared to the information in Hermes 1 PSAR Section 9.1.5, is the following:

x Each unit has its own RTMS and there are no components shared between the units.

The RTMS does not perform safety-related functions. Additionally, each unit having its own RTMS will prevent one failure in the system from affecting both units. Based on the above, the staff finds that each unit having its own RTMS is acceptable.

On the basis of its review, the staff finds that the level of detail regarding the RTMS demonstrates an adequate basis for a preliminary design and satisfies the applicable acceptance criteria in NUREG-1537, Part 2, Section 9.7, to not result in accidents or unacceptable radioactivity releases and for no function or malfunction of the RTMS to interfere with or prevent safe shutdown of the reactor.

9.1.5.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the information on the RTMS in PSAR Section 9.1.5 is sufficient and meets applicable guidance and regulatory requirements identified in this section for issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. The staff concludes that the preliminary design features intended to minimize contamination and support eventual decommissioning are consistent with the requirements of 10 CFR 20.1406.

9.2 Reactor Building Heating, Ventila tion, and Air Conditioning System

9.2.1 Introduction

Section 9.2, Reactor Building Heating, Ventilation, and Air Conditioning System, of the Hermes 2 PSAR describes the RBHVAC. The RBHVAC is not proposed to provide any safety-related function or support any safety-related SSCs. Although radiation monitoring and filtration will be provided, the RBHVAC is not needed to mitigate any postulated event. No technical specifications are proposed for the RBHVAC. Each Hermes 2 unit has its own RBHVAC and there are no shared components between the units. The RBHVAC performs the following non-safety-related functions:

x Maintain environmental conditions (air quality, temperature, humidity, pressure, and noise levels) for personnel health, habitability, and for SSC operability x Provide a means to control and monitor tritium, beryllium, and other controlled effluents x Monitor exhaust air vented from the reactor building for controlled effluents x Ensure ventilation flow from areas of low hazard to areas of higher hazard potential x Minimize contamination of facility areas

9.2.2 Regulatory Evaluation

The staff reviewed Section 9.2.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the RBHVAC design between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.2.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.2.2 of the Hermes 1 SE.

9.2.3 Technical Evaluation

The staff reviewed Section 9.2 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.2, Reactor Building Heating, Ventilation, and Air Conditioning System). The staff found that Section 9.2 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for the minor change evaluated below. The staff also verified that the Hermes 2 RBHVAC design and functionality remain identical to Hermes 1. Based on these consistencies, this section incorporates by reference Section 9.2.3, Technical Evaluation, of the Hermes 1 SE.

9.2.3.1 Minor Change Compared to the Hermes 1 PSAR

The minor change in Hermes 2 PSAR Section 9.2, as compared to the information in Hermes 1 PSAR Section 9.2, is the following:

x Each unit has its own RBHVAC and there are no components shared between the units.

The RBHVAC does not perform safety-related functions. Additionally, each unit having its own RBHVAC will prevent one failure in the system from affecting both units. Based on the above, the staff finds that each unit having its own RBHVAC is acceptable.

On the basis of its review, the staff finds that the level of detail provided regarding the Hermes 2 RBHVAC demonstrates an adequate basis for a preliminary design and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.1, Heating, Ventilation, and Air Conditioning Systems, to support the as low as reasonably achievable (ALARA) program, radiation monitoring, and contamination control functions.

9.2.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the information in Hermes 2 PSAR Section 9.2 is sufficient and meets the applicable guidance and regulatory requirements identified in this section for issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. Additionally, the staff concludes that the design features and analyses described in the PSAR provide reasonable assurance that Kairos will meet 10 CFR 20.1101(b), 10 CFR 20.1101(d), and 10 CFR 20.1406.

9.3 Pebble Handling and Storage System

9.3.1 Introduction

Section 9.3, Pebble Handling and Storage System, of the Hermes 2 PSAR describes a preliminary design for the PHSS, which provides for handling and storing fuel and other pebbles. The system encompasses receipt and inspection of new fuel upon delivery, core loading, sensing, inspection and sorting during downstream circulation, re-insertion, core unloading, and removal and transfer to storage. Each Hermes 2 unit has its own PHSS and there are no shared components between the units.

9.3.2 Regulatory Evaluation

The staff reviewed Section 9.3.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the PHSS design between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.3.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.3.2 of the Hermes 1 SE.

9.3.3 Technical Evaluation

The staff reviewed Section 9.3 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.3, Pebble Handling and Storage System). The staff found that Section 9.3 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for two minor changes and one significant change evaluated below in Sections 9.3.3.1 and 9.3.3.2, respectively. The staff found that the following portions of Section 9.3 in the Hermes 2 PSAR contain information consistent with the Hermes 1 PSAR (e.g., minor or editorial changes only):

x Section 9.3.1.1, Pebble Extraction Machine, through 9.3.1.7, PHSS Inert Gas Boundary x Sections 9.3.1.9, New Fuel Pebble Introduction, and 9.3.2, Design Bases x Section 9.3.4, Testing and Inspection

Since the Hermes 2 system design and functionality largely remain identical, excepting the differences evaluated below, there are few changes to the PHSS design in Section 9.3 of the Hermes 2 PSAR when compared to Section 9.3 of the Hermes 1 PSAR. Based on these consistencies, this section incorporates by reference Section 9.3 of the Hermes 1 SE.

9.3.3.1 Minor Changes Compared to the Hermes 1 PSAR

The minor changes in Hermes 2 PSAR Section 9.3, as compared to the information in Hermes 1 PSAR Section 9.3, include the following:

x Each of the Hermes 2 units will have its own PHSS.

x The storage bay will be sized sufficiently for the 11-year operating life of Hermes 2 rather than the 4-year operating life of Hermes 1.

Each unit having its own PHSS will prevent one failure in the system from affecting both units.

The increased size of the PHSS storage bay is appropriate due to the increased amount of spent fuel, and the air cooling for the storage bay is designed to effectively cool the increased amount of spent fuel under normal and postulated events. This increased size and proper cooling allows for geometrically safe configurations during storage. Based on the above, the staff finds that each unit having its own PHSS and the increased storage bay size are acceptable.

9.3.3.2 Significant Change Compared to the Hermes 1 PSAR

The significant change contained in Section 9.3 of the Hermes 2 PSAR, as compared to Section 9.3 of the Hermes 1 PSAR, includes information regarding the following:

x The addition of design and construction information regarding the spent fuel storage racks.

These changes are identified in PSAR Section 9.3.1.8, Pebble Storage and PSAR Section 9.3.3, System Evaluation.

The staff evaluated the sufficiency of this additional preliminary information regarding the Hermes 2 spent fuel storage racks using the guidance and acceptance criteria of NUREG-1537, Part 2, Section 9.2, Handling and Storage of Reactor Fuel. In PSAR Table 3.6-1, Kairos lists the air-cooled and water-cooled spent fuel storage racks as safety-related and quality-related and to be designed as seismic design category 3 structures. PSAR Section 9.3.1.8 states the safety function of the spent fuel storage racks is to store the fuel storage canisters in a configuration that precludes criticality and supports heat removal. The staff finds that the safety and seismic classification of spent fuel storage racks is consistent with the graded approach of the American Society of Civil Engineers (ASCE) 43-19, Seismic Design Criteria for Structures, Systems, and Components in Nuclear Facilities, and the applicable guidance in NUREG-1537 and is, therefore, acceptable.

Kairos states the racks will be constructed of stainless steel meeting American Society for Testing and Materials (ASTM) A240, Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications, and the racks will be designed following American Institute of Steel Construction (AISC) N690-18, Specification for Safety-Related Steel Structures for Nuclear Facilities, and AISC 370-21, Specification for Structural Stainless Steel Buildings. AISC N690-18 has been endorsed by the staff with the exceptions and clarifications listed in NRC Regulatory Guide (RG) 1.243, Safety-Related Steel Structures and Steel-Plate Composite Walls for Other than Reactor Vessels and Containments. The staff considers the use of AISC N690-18, in conjunction with AISC 370-21 and its references to AISC Design Guide 27, Structural Stainless Steel, to be sufficient for designing the Hermes 2 spent fuel storage racks considering that AISC N690-18 is endorsed in RG 1.243. However, AISC 370-21 has not yet been reviewed by the staff for generic endorsement. The staff will perform a case-specific detailed review of the final design of the spent fuel storage racks during its evaluation of the OL application. This case-specific review will evaluate the ability of the structural design to adequately ensure the safety function of the racks, including any deviations of the structures from the typical structures addressed in AISC N690-18 and AISC 370-21.

Kairos evaluates the spent fuel storage racks designs in PSAR Section 9.3.3 with additional details of the fuel handling and drop analysis being provided in PSAR Section 9.3.1.8.2, Fill, Sealing, and Movement. The structural analysis of the spent fuel storage racks will use the load combinations in PSAR Table 3.5-1 with the addition of an impact load from a dropped storage canister. Kairos did not identify a specific load combination for the impact load from a dropped storage canister, but will provide it for as part of the drop analysis in the OL application.

Moving spent fuel canisters requires a fuel canister transporter, which contains one canister at a time, and a canister lifting device, which moves a canister between the transporter and the spent fuel storage racks. Kairos will analyze the impact of a storage canister dropped from the canister lifting device onto the spent fuel storage racks in the OL application. A drop of the fuel canister transporter or a canister from the transporter onto the spent fuel storage racks is not considered since the transporter complies with American Society of Mechanical Engineers (ASME) BTH-1-2017, Design of Below-the-Hook Lifting Devices, and is supported by a transporter crane designed as a Type I crane per ASME NOG-1-2020, Rules for Construction of Overhead and Gantry Cranes (Top Running Bridge, Multiple Girder). The staff finds the use of these standards to be consistent with RG 1.244, Control of Heavy Loads at Nuclear Facilities, and constitutes a highly reliable (i.e., single-failure proof) handling system, which does not require a drop analysis to demonstrate adequate safety. Additionally, Kairos states that the storage cannisters will be designed to preclude interference with the spent fuel storage racks during insertion and removal, therefore, Kairos does not consider an upward force on the racks can be caused by a stuck fuel canister. The staff finds that by preventing interference by the design of the storage canisters, it is acceptable for Kairos to not analyze for upward loads on the spent fuel storage racks. A more detailed review of the spent fuel canister and spent fuel storage rack designs will occur during the review of the Hermes 2 OL application, at which time the staff will confirm that the final design conforms to the design basis.

Based on the above, the staff finds that the preliminary design information in the PSAR is sufficient to determine that the spent fuel storage racks should perform their safety functions of precluding criticality and supporting heat removal.

On the basis of its review, the staff finds that the level of detail provided regarding the Hermes 2 PHSS demonstrates an adequate basis for a preliminary design and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.3, to support functions like maintaining subcriticality, preventing damage to pebbles, limiting radiation exposure, and material control and accounting.

9.3.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the preliminary design of the PHSS, as described in the Hermes 2 PSAR, is sufficient and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff also concludes that the preliminary design features related to criticality safety are consistent with the requirements of 10 CFR 70.24, Criticality accident requirements, and the preliminary design features intended to minimize contamination and support eventual decommissioning provide reasonable assurance that Kairos will meet the requirements of 10 CFR 20.1406(a) for the Hermes 2 facility. Further technical or design information required to approve operation of the PHSS will be evaluated in the review of the OL application.

9.4 Fire Protection Systems and Programs

9.4.1 Introduction

Section 9.4, Fire Protection Systems and Programs, of the Hermes 2 PSAR describes a preliminary design for fire protection systems and related programs. The fire protection program integrates components, procedures, analysis, and personnel used to define and carry out all activities of fire protection. The fire protection system is designed to detect, control, and extinguish fires so that a continuing fire will not prevent safe shutdown or result in an uncontrolled release of radioactive material that exceeds acceptance criteria. The Hermes 2 fire protection systems consist of unit-specific systems that serve each reactor building and common systems that serve the shared turbine building and the shared main control room.

Kairos stated that a detailed description of the fire protection program and a fire hazards analysis will be provided with the application for an OL.

9.4.2 Regulatory Evaluation

The staff reviewed Section 9.4.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the fire protection systems and programs between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.4.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.4.2 of the Hermes 1 SE.

9.4.3 Technical Evaluation

The staff reviewed Section 9.4 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.4, Fire Protection Systems and Programs). The staff found that Section 9.4 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for minor changes evaluated below. The staff also verified that the Hermes 2 fire protection systems and programs design and functionality remain similar to Hermes 1. Based on these consistencies, this section incorporates by reference Section 9.4.3, Technical Evaluation, of the Hermes 1 SE.

9.4.3.1 Minor Changes Compared to the Hermes 1 PSAR

The minor changes in Hermes 2 PSAR Section 9.4, as compared to the information in Hermes 1 PSAR Section 9.4, include the following:

x There is one common fire protection program for the Hermes 2 site.

x The fire protection systems consist of unit-specific systems that serve each reactor building and common systems that serve the shared turbine building and the shared main control room.

In Hermes 2 PSAR Section 9.4, Kairos states that Unit 1 and Unit 2 will have one common fire protection program and that there will be unit-specific systems for each reactor building and common systems for other areas. This approach is consistent with the facility having two units compared to the one unit of Hermes 1. The use of unit-specific systems for each reactor building, common systems that serve shared structures and systems, and a common fire protection program is an appropriate design and program structure for a two-unit facility. Based on the above, the staff finds that having unit-specific and common fire protection systems is acceptable.

Additionally, Hermes 2 PSAR Section 7.4, Main Control Room and Remote Onsite Shutdown Panel, contains changes that are applicable to fire protection systems and programs. The applicable minor changes, as compared to the information in Hermes 1 PSAR Section 7.4, Main Control Room and Remote Onsite Shutdown Panel, include the following:

x The main control room is shared between Unit 1 and Unit 2 and provides the means for operators to monitor each unit and shared systems, control the performance of each unit and the shared systems, and manage the response to postulated event conditions in each unit.

x Unit-specific remote onsite shutdown panels (ROSP) are now provided that separate the means to shut down each unit and monitor plant parameters in response to postulated event conditions. Additionally, the ROSPs are located in the safety-related portion of the reactor building for each unit.

These changes provide the capabilities to monitor and control each unit inside and outside the control room in the event of a fire and the staff finds that the preliminary design is consistent with PDC 19, Control Room. Based on the above, the staff finds that having a common main control room and individual RSOPs to support the response to a postulated fire event is acceptable.

On the basis of its review, the staff finds that the level of detail provided regarding the Hermes 2 fire protection systems and programs demonstrates an adequate basis for a preliminary design and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.3, Fire Protection Systems and Programs, to support post-fire safe shutdown.

9.4.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 PSAR, the staff concludes that information provided in the PSAR meets the regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. Based on the information provided in the PSAR, the staff also concludes that the preliminary description of the fire protection program and the fire protection systems demonstrate an adequate design basis for a preliminary design so that the requirements of 10 CFR 50.34(a) are met. Further programmatic, technical, or design information required to approve operation of the test reactor will be evaluated in the review of the OL application.

9.5 Communication Systems

9.5.1 Introduction

Section 9.5, Communication, of the Hermes 2 PSAR describes a preliminary design for the Hermes 2 communication systems. Hermes 2 PSAR, Section 9.5.1, Description, states that the communication systems provide communications during normal and emergency conditions between essential areas of the facility and between locations remote to the facility. The communication systems are common systems shared between the Hermes 2 units. The communication systems are not safety-related, are not credited for mitigation of design basis events, and have no safe shutdown function.

9.5.2 Regulatory Evaluation

The staff reviewed Section 9.5.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the communication systems between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.5.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.5.2 of the Hermes 1 SE.

9.5.3 Technical Evaluation

The staff reviewed Section 9.5 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.5, Communication Systems). The staff found that Section 9.5 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for the minor change evaluated below. The staff also verified that the Hermes 2 communication systems design and functionality remain similar to Hermes 1. Based on these consistencies, this section incorporates by reference Section 9.5.3, Technical Evaluation, of the Hermes 1 SE.

9.5.3.1 Minor Change Compared to the Hermes 1 PSAR

The minor change in Hermes 2 PSAR Section 9.5, as compared to the information in Hermes 1 PSAR Section 9.5, is the following:

x The communication systems are common systems shared between Unit 1 and Unit 2

The sharing of communication systems across the single facility is appropriate because personnel should be made aware of events and activities occurring in one unit or common areas that could affect the entire facility. Additionally, the sharing of communication systems in dual unit sites has been standard for the currently operating reactor fleet for decades. Based on the above, the staff finds that having shared communication systems is acceptable.

On the basis of its review, the staff finds that the level of detail provided regarding the Hermes 2 communication systems demonstrates an adequate basis for a preliminary design and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.4, Communication Systems.

9.5.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the design of the Hermes 2 communication systems, as described in Hermes 2 PSAR Section 9.5, is sufficient and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. A more detailed evaluation of this information will occur during the review of the Hermes 2 OL application, at which time the staff will confirm that the final design conforms to this design basis.

9.6 Possession and Use of Byproduct, Source, and Special Nuclear Material

9.6.1 Introduction

Section 9.6, Possession and Use of Byproduct, Source, and Special Nuclear Material, of the Hermes 2 PSAR discusses radioactive materials, including byproduct material, source material, and SNM that will be present at the Hermes 2 facility. PSAR Section 9.6 also discusses locations where these materials will be stored or used at the facility, systems that interact with these materials and controls for handling these materials. PSAR Section 9.6 states that the design bases for systems interacting with byproduct, source, or SNM are to prevent uncontrolled releases of radioactive materials and to maintain any Kairos personnel exposures within 10 CFR Part 20 dose limits and ALARA objectives.

PSAR Section 9.6 states that Kaiross Hermes 2 CP application does not request authorization to possess any radioactive material, and that amendments or applications for license(s) allowing such possession of such material would be submitted at later date(s). During the general audit for Hermes 1 (ML23115A480), Kairos stated that it planned to possess byproduct, source and SNM associated with operation under a 10 CFR Part 50 OL for Hermes 1, but that it might also request authorization to possess such materials prior to the issuance of an OL through a CP amendment request, for example. Possession of radioactive material by Kairos would be evaluated when an application is submitted to the NRC. Kairos confirmed that this same approach will be taken for Hermes 2 by letter dated October 27, 2023 (ML23300A144).

9.6.2 Regulatory Evaluation

The staff reviewed Section 9.6.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the approach to possession of radioactive material between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.6.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.6.2 of the Hermes 1 SE.

9.6.3 Technical Evaluation

The staff reviewed Section 9.6 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.6, Possession and Use of Byproduct, Source, and Special Nuclear Material). The staff found that Section 9.6 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR except for the minor change evaluated below. The staff also verified that the Hermes 2 approach to the possession and use of byproduct, source, and SNM remains identical to Hermes 1. Based on these consistencies, this section incorporates by reference Section 9.6.3, Technical Evaluation, of the Hermes 1 SE.

9.6.3.1 Minor Change Compared to the Hermes 1 PSAR

The minor change in Hermes 2 PSAR Section 9.6, as compared to the information in Hermes 1 PSAR Section 9.6, is the following:

x Hermes 2 PSAR Section 9.6.3 added the IHTS and the PGS to the list of systems which may contain tritium.

The IHTS and PGS are new systems for the Hermes 2 design and may contain tritium.

Hermes 2 PSAR Sections 5.2, Intermediate Heat Transport System, 9.1.3, and 9.6.3 state that the TMS manages the inventory of tritium in the reactor system, including the IHTS, to reduce environmental releases. Hermes 2 PSAR Sections 9.9.1, Steam System, and 9.9.3, Condensate and Feedwater System, also discuss the control and monitoring of tritium releases from the PGS. The staff reviewed the information on the preliminary design of the IHTS, TMS, and PGS and found it acceptable for the issuance of CPs as discussed in SE Sections 5.2, Intermediate Heat Transport System, 9.1.3, and 9.9, respectively.

Additionally, as discussed in Hermes 2 PSAR Section 13.2.1, Accident Analysis and Determination of Consequences, the radioactive material at risk of release (MAR) calculation for the maximum hypothetical accident (MHA) accounts for a bounding initially generated amount of tritium in total for the reactor, not the amount of tritium in each individual system. The MHA analysis uses bounding estimates of the radionuclides in the circulating activity MAR and the structural MAR, and it also uses bounding estimates for the transport and release of those MAR sources. As discussed in Hermes 2 PSAR Chapter 14, Technical Specifications, MAR quantities will also be controlled by upper bound limits in the technical specifications (TS) to help ensure that the assumptions in the MHA remain bounding for all facility operating conditions. Therefore, the staff finds that the consequences of a potential release of tritium for Hermes 2, including in the IHTS and PGS, will be within the bounds of the MHA, and that routine operational releases of tritium will also be controlled to help ensure that any releases are within 10 CFR Part 20 dose limits and ALARA. Based on the above, the staff finds that accounting for tritium in the IHTS and PGS is acceptable.

On the basis of its review, the staff finds that the level of detail provided in Hermes 2 PSAR Section 9.6 and other PSAR sections regarding the Hermes 2 possession and use of byproduct, source, and SNM demonstrates an adequate basis for a preliminary design and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.5, Possession and Use of Byproduct, Source, and Special Nuclear Material. Based on this review, the staff finds that: (1) the auxiliary facilities and systems are designed for the possession and use of source material, SNM, and byproduct material located at Hermes 2 and produced by the reactor and (2) the Hermes 2 design provides reasonable assurance that the uncontrolled release of radioactive material to the unrestricted environment and public will not occur. Because the design bases include limits on potential personnel exposures, the staff has reasonable assurance that Kairos will comply with the regulations in 10 CFR Part 20 and the ALARA program during Hermes 2 facility operation.

9.6.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the information provided in the PSAR and the preliminary design of the Kairos program and auxiliary facilities for the possession and use of byproduct material, source material, and SNM at Hermes 2, as described in the PSAR, is sufficient and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff also concludes that the preliminary design and programs described in the PSAR provide reasonable assurance that Kairos will comply with 10 CFR Part 20 during operation. Further technical or design information required to approve operation of the test reactor will be evaluated in the review of the OL application.

9.7 Plant Water Systems

Section 9.7, Plant Water Systems, of the Hermes 2 PSAR describes four auxiliary water systems:

x Service water x Treated water x Component cooling water (CCWS) x Chilled water

The auxiliary water systems do not provide any safety-related function or support any safety-related SSCs, are not needed to mitigate any postulated event, and are not credited with performing safe shutdown functions. No TS are proposed in the PSAR for these water systems.

These water systems perform the following non-safety-related functions:

x Supply, treat, and store water x Distribute water for cooling and maintenance x Remove heat from non-essential loads x Remove heat from essential loads x Discharge heat to the environment

The introduction to PSAR Section 9.7 states that water systems which directly interface with systems containing radioactive material will be designed to meet the requirements of 10 CFR 20.1406. As indicated by PSAR Figure 9.7-1, Plant Water System Process Flow Diagram, only the CCWS interfaces with systems containing radioactive material in the current design. Kairos confirmed in the general audit that, in the final design, any auxiliary water systems that connect to a system containing radioactive material will be designed to meet the requirements of 10 CFR 20.1406.

9.7.1 Regulatory Evaluation for Auxiliary Water Systems

The staff reviewed Section 9.7.1, Regulatory Evaluation for Auxiliary Water Systems, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the auxiliary water systems design between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.7.1 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.7.1 of the Hermes 1 SE.

9.7.2 Service Water System

9.7.2.1 Introduction

Section 9.7.1, Service Water System, from the Hermes 2 PSAR describes how the service water system draws water from municipal sources and provides the water to other water systems and supports general facility services (e.g., potable water). The service water system is not safety-related and is not credited for the mitigation of postulated events. The service water system is designed in accordance with local building codes. The service water system is a common system shared between Unit 1 and Unit 2.

9.7.2.2 Technical Evaluation

PDC applicable to the service water system are:

x PDC 2, "Design Bases for Protection Against Natural Phenomena" x PDC 4, Environmental and Dynamic Effects Design Bases

Section 9.7.1 of the Hermes 2 PSAR describes the service water system as a supply system for other water systems and for general facility use. No portion of the service water system will be located in the proximity of safety-related SSCs. As described in PSAR Section 3.5.3.2, Conformance with PDC 2 for Internal and External Flooding, the design of the safety-related portion of each reactor building includes features to protect vulnerable safety-related SSCs from the effects of potential internal flooding and water spray that may result from the failure of water systems outside the safety-related portion of the building, whether due to the effects of natural phenomena or other conditions. Thus, the staff finds that the preliminary design of the service water system is consistent with PDC 2 and PDC 4 regarding the effects of damage that could result from natural phenomena or other postulated events that involve failure of the service water system. Consistent with the guidance of NUREG-1537, Part 2, Section 9.7, for auxiliary system operation and potential malfunctions, the Hermes 2 service water system has been designed such that it will not cause accidents affecting the reactor, uncontrolled releases of radioactivity, or interference with safe shutdown of the reactor.

9.7.2.3 Conclusion

Based on the findings above, the staff concludes that the preliminary design of the service water system is sufficient and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. A more detailed evaluation of the service water system design will occur during the review of the Hermes 2 OL application, at which time the staff will confirm that the final design conforms to this design basis.

9.7.3 Treated Water System

9.7.3.1 Introduction

Section 9.7.2, Treated Water System, of the Hermes 2 PSAR describes how the treated water system provides chemistry control and supplies make-up water to the CCWS and the safety-related decay heat removal system. Portions of the treated water system may be located in proximity to SSCs with safety-related functions, and portions of the system may cross the base-isolation moat that provides seismic protection for the reactor cell and PHSS cell. The treated water system is not safety-related and is not credited for the mitigation of postulated events. The treated water system is designed in accordance with local building codes. Portions of the treated water system are shared between Unit 1 and Unit 2.

9.7.3.2 Technical Evaluation

PDC applicable to treated water system are:

x PDC 2, Design Bases for Protection Against Natural Phenomena x PDC 4, Environmental and Dynamic Effects Design Bases

Section 9.7.2, Treated Water System, of the Hermes 2 PSAR describes how the treated water system design features and features of the reactor building satisfy the above design criteria.

Because portions of the treated water system may be located in proximity to SSCs with safety-related functions, those safety-related SSCs will be protected either by seismically mounting nearby treated water system components or installation of barriers to prevent adverse interactions. As described in PSAR Section 3.5.3.2, the design of the safety-related portion of each reactor building includes features to protect vulnerable safety-related SSCs from the effects of potential internal flooding and water spray that may result from the failure of water systems within and outside the safety-related portion of the building, whether due to the effects of natural phenomena or other conditions. Thus, the staff finds that the preliminary design of the treated water system is consistent with PDC 2 and PDC 4 regarding the effects of damage that could result from natural phenomena or other postulated events that involve failure of the treated water system. Consistent with the guidance of NUREG-1537, Part 2, Section 9.7, the treated water system satisfies guidance for auxiliary system malfunctions such that it would not initiate a reactor accident, initiate an uncontrolled release of radioactivity, or interfere with safe shutdown of the reactor.

9.7.3.3 Conclusion

Based on the staff findings above, the staff concludes that the preliminary design of the treated water system is sufficient and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. A more detailed evaluation of the treated water system design will occur during the review of the Hermes 2 OL application, at which time the staff will confirm that the final design conforms to this design basis.

9.7.4 Component Cooling Water System

9.7.4.1 Introduction

Section 9.7.3, Component Cooling Water System, describes how the CCWS provides cooling water for the RBHVAC, the ESCS, the SFCS, and the IGS. The CCWS is managed by the plant control system to maintain desired operational temperature limits. Heat from the CCWS is rejected to the environment. Each unit has its own CCWS and there are no shared components between the units. The CCWS does not perform safety-related functions and is not credited for the mitigation of postulated events. Portions of the CCWS may be located in proximity to SSCs with safety-related functions, and portions of the system may cross the base-isolation moat that provides seismic protection for the reactor cell and PHSS cell. As shown in PSAR Table 3.6-1, Structures, Systems, and Components, the CCWS is designed in accordance with local building codes.

9.7.4.2 Technical Evaluation

PDC applicable to the CCWS are:

x PDC 2, Design Bases for Protection Against Natural Phenomena x PDC 4, Environmental and Dynamic Effects Design Bases x PDC 44, Structural and Equipment Cooling x PDC 45, Inspection of Structural and Equipment Cooling Systems x PDC 46, Testing of Structural and Equipment Cooling Systems

Section 9.7.3 of the PSAR provides a description of the CCWS and identifies how the CCWS satisfies the above design criteria. Because portions of the CCWS may be located in proximity to SSCs with safety-related functions, those safety-related SSCs will be protected either by seismically mounting nearby CCWS components or installation of barriers to prevent adverse interactions. As described in PSAR Section 3.5.3.2, Conformance with PDC 2 for Internal and External Flooding, the design of the safety-related portion of each reactor building includes features to protect vulnerable safety-related SSCs from the effects of potential internal flooding and water spray that may result from the failure of water systems within and outside the safety-related portion of the building, whether due to the effects of natural phenomena or other conditions. Thus, the staff finds that the preliminary design of the CCWS is consistent with PDC 2 and PDC 4 regarding the effects of damage that could result from natural phenomena or other postulated events that involve failure of the CCWS.

The CCWS transfers heat from safety significant SSCs such as the fuel storage pool under normal operating conditions, but performs no safety-related heat transfer functions for accident mitigation. The CCWS design provides for periodic inspection and testing to ensure the integrity and capability of the system to cool SSCs and to adequately transfer heat to the ultimate heat sink. Based on this capability, the staff finds that the preliminary design of the CCWS is consistent with PDC 44, PDC 45, and PDC 46.

Kairos has adequately described the design bases of the CCWS in PSAR Sections 9.7 and 9.7.3. The staff finds that the CCWS preliminary design, as described in the PSAR, is consistent with PDC 2, PDC 4, PDC 44, PDC 45, PDC 46, and the guidance of NUREG-1537, Part 2, Section 9.7, with regard to performing heat transfer functions consistent with the system design basis and ensuring auxiliary system malfunctions would not initiate a reactor accident, initiate an uncontrolled release of radioactivity, or interfere with safe shutdown of the reactor.

9.7.4.3 Conclusion

Based on the staffs findings above, the staff concludes that the preliminary design of the CCWS is sufficient and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. A more detailed evaluation of the CCWS design will occur during the review of the Hermes 2 OL application, at which time the staff will confirm that the final design conforms to this design basis.

9.7.5 Chilled Water System

9.7.5.1 Introduction

Section 9.7.4, Chilled Water System, of the Hermes 2 PSAR states that the chilled water system provides cooling water to the RBHVAC system and other facility SSCs that are not safety-related. The chilled water system is not safety-related and is not credited for the mitigation of postulated events. The chilled water system is designed in accordance with local building codes. Each unit has its own chilled water system and there are no shared components between the units.

9.7.5.2 Technical Evaluation

PDC applicable to chilled water system are:

x PDC 2, Design Bases for Protection Against Natural Phenomena x PDC 4, Environmental and Dynamic Effects Design Bases

Section 9.7.4 of the PSAR provides a description of the chilled water system and identifies how the chilled water system satisfies the above design criteria. No portion of the chilled water system will be located in the proximity of safety-related SSCs. As described in PSAR Section 3.5.3.2, the design of the safety-related portion of each reactor building includes features to protect vulnerable safety-related SSCs from the effects of potential internal flooding and water spray that may result from the failure of water systems outside the safety-related portion of the building, whether due to the effects of natural phenomena or other conditions.

Thus, the staff finds that the preliminary design of the chilled water system is consistent with PDC 2 and PDC 4 regarding the effects of damage that could result from natural phenomena or other postulated events that involve failure of the chilled water system. Consistent with NUREG-1537, Part 2, Section 9.7, the chilled water system satisfies guidance for auxiliary system malfunctions such that it would not initiate a reactor accident, initiate an uncontrolled release of radioactivity, or interfere with safe shutdown of the reactor.

9.7.5.3 Conclusion

Based on the staff findings above, the staff concludes that the preliminary design of the chilled water system is sufficient and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. A more detailed evaluation of the chilled water system design will occur during the review of the Hermes 2 OL application, at which time the staff will confirm that the final design conforms to this design basis.

9.8 Other Auxiliary Systems

9.8.1 Remote Maintenance and Inspection System

9.8.1.1 Introduction

Section 9.8.1, Remote Maintenance and Inspection System, of the Hermes 2 PSAR describes how the remote maintenance and inspection system (RMIS) will provide the ability to remotely access, inspect, and handle components in the reactor system, the PHTS, and the PHSS. The RMIS is located in the reactor building and includes manipulators, tooling, cameras, monitors, cranes and rigging. The RMIS is not safety-related and does not perform safety-related functions. Portions of the system may cross the base-isolation moat that provides seismic protection for the reactor cell and PHSS cell. Each unit has its own RMIS and there are no components shared between the units.

9.8.1.2 Regulatory Evaluation

The staff reviewed Section 9.8.1.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the RMIS design between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.8.1.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.8.1.2 of the Hermes 1 SE.

9.8.1.3 Technical Evaluation

The staff reviewed Section 9.8.1 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.8.1, Remote Maintenance and Inspection System).

The staff found that Section 9.8.1 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for the minor change evaluated below. The staff also verified that the Hermes 2 RMIS design and functionality remain identical to Hermes 1. Based on these consistencies, this section incorporates by reference Section 9.8.1.3, Technical Evaluation, of the Hermes 1 SE.

9.8.1.3.1 Minor Change Compared to the Hermes 1 PSAR

The minor change in Hermes 2 PSAR Section 9.8.1, as compared to the information in Hermes 1 PSAR Section 9.8.1, is the following:

x Each unit has its own RMIS and there are no components shared between the units.

The RMIS does not perform safety-related functions. Additionally, each unit having its own RMIS will prevent one RMIS failure from affecting both units. Based on the above, the staff finds that each unit having its own RMIS is acceptable.

On the basis of its review, the staff finds that the level of detail provided regarding the Hermes 2 RMIS demonstrates an adequate basis for a preliminary design and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.7, for auxiliary systems to not cause accidents to the reactor, uncontrolled release of radioactivity, or interfere with safe shutdown of the reactor.

9.8.1.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the preliminary design of the RMIS is sufficient and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. The staff also concludes that the design features described in the PSAR help provide reasonable assurance that Kairos will comply with 10 CFR 20.1101(b) and 10 CFR 20.1406. A more detailed evaluation of the RMIS design will occur during the review of the Hermes 2 OL application, at which time the staff will confirm that the final design conforms to this design basis.

9.8.2 Spent Fuel Cooling System

9.8.2.1 Introduction

Section 9.8.2, Spent Fuel Cooling System, of the Hermes 2 PSAR describes a preliminary design for the SFCS, which cools spent fuel canisters in the spent fuel storage pool and storage bay. PSAR Section 9.8.2 states that the system does not perform safety-related functions.

9.8.2.2 Regulatory Evaluation

The staff reviewed Section 9.8.2.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the SFCS design between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.8.2.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.8.2.2 of the Hermes 1 SE.

9.8.2.3 Technical Evaluation

The staff reviewed Section 9.8.2 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.8.2, Spent Fuel Cooling System). The staff found that Section 9.8.2 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for minor changes evaluated below. The staff also verified that the Hermes 2 SFCS design and functionality remain identical to Hermes 1. Based on these consistencies, this section incorporates by reference Section 9.8.2.3, Technical Evaluation, of the Hermes 1 SE.

9.8.2.3.1 Minor Changes Compared to the Hermes 1 PSAR

The minor changes in Hermes 2 PSAR Section 9.8.2, as compared to the information in Hermes 1 PSAR Section 9.8.2, include the following:

x The number of pebbles that each units SFCS is sized to cool was increased to account for the higher number generated during 11 years of operation for Hermes 2 versus the 4 years of operation of Hermes 1.

x Each unit has its own SFCS and there are no components shared between the units.

Because the system does not perform safety-related functions, increasing the cooling capacity of the system does not affect reactor safety and is appropriate for the increased operational life of Hermes 2. Additionally, each unit having its own SFCS will prevent one failure in the system from affecting both units. Based on the above, the staff finds that the increase in pebble (cooling) capacity and each unit having its own SFCS are acceptable.

On the basis of its review, the staff finds that the level of detail provided regarding the Hermes 2 SFCS demonstrates an adequate basis for a preliminary design and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.2, Handling and Storage of Reactor Fuel, to support functions including preventing thermal failure and limiting radiation exposure.

9.8.2.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the preliminary design of the SFCS, as described in the PSAR, is sufficient and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. The staff also concludes that the preliminary design features intended to minimize contamination and support eventual decommissioning will help ensure compliance with the requirements of 10 CFR 20.1406.

Further technical or design information required to approve operation of Hermes 2 will be evaluated in the review of an OL application.

9.8.3 Compressed Air System

9.8.3.1 Introduction

Section 9.8.3, Compressed Air System, of the Hermes 2 PSAR states that the compressed air system provides compressed air for general facility services and for use in valve operation. The compressed air system is not safety-related and is not credited with performing safe shutdown functions. Each unit has its own compressed air system and there are no shared components between the units.

9.8.3.2 Regulatory Evaluation

The staff reviewed Section 9.8.3.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the compressed air system design between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.8.3.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.8.3.2 of the Hermes 1 SE.

9.8.3.3 Technical Evaluation

The staff reviewed Section 9.8.3 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.8.3, Compressed Air System). The staff found that Section 9.8.3 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for the minor change evaluated below. The staff also verified that the Hermes 2 compressed air system design and functionality remain identical to Hermes 1. Based on these consistencies, this section incorporates by reference Section 9.8.3.3, Technical Evaluation, of the Hermes 1 SE.

9.8.3.3.1 Minor Change Compared to the Hermes 1 PSAR

The minor change in Hermes 2 PSAR Section 9.8.3, as compared to the information in Hermes 1 PSAR Section 9.8.3, is the following:

x Each unit has its own compressed air system and there are no components shared between the units.

The compressed air systems do not perform safety-related functions. Additionally, each unit having its own compressed air system will prevent one failure in the system from affecting both units. Based on the above, the staff finds that each unit having its own compressed air system is acceptable.

On the basis of its review, the staff finds that the level of detail provided regarding the Hermes 2 compressed air system demonstrates an adequate basis for a preliminary design and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.7, for auxiliary systems to not cause accidents to the reactor, uncontrolled release of radioactivity, or interfere with safe shutdown of the reactor.

9.8.3.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the preliminary design of the compressed air system is sufficient and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. A more detailed evaluation of the compressed air system design will occur during the review of the Hermes 2 OL application, at which time the staff will confirm that the final design conforms to this design basis.

9.8.4 Cranes and Rigging

9.8.4.1 Introduction

Section 9.8.4, Cranes and Rigging, of the Hermes 2 PSAR describes that each unit has a reactor building gantry crane to move equipment and support material receiving and shipping.

Because of the heavy loads that would be lifted by the cranes, failure or mis-operation of the cranes could damage safety-related SSCs if a load was to drop. The reactor building cranes and associated rigging are not safety-related, perform no safety-related functions, and share no components between the units.

9.8.4.2 Regulatory Evaluation

The staff reviewed Section 9.8.4.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the cranes and rigging design between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.8.4.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.8.4.2 of the Hermes 1 SE.

9.8.4.3 Technical Evaluation

The staff reviewed Section 9.8.4 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.8.4, Cranes and Rigging). The staff found that Section 9.8.4 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for minor changes evaluated below. The staff also verified that the Hermes 2 reactor building cranes and rigging design and functionality remain identical to Hermes 1. Based on these consistencies, this section incorporates by reference Section 9.8.4.3, Technical Evaluation, of the Hermes 1 SE.

9.8.4.3.1 Minor Changes Compared to the Hermes 1 PSAR

The minor changes in Hermes 2 PSAR Section 9.8.4, as compared to the information in Hermes 1 PSAR Section 9.8.4, include the following:

x Each unit has its own reactor building cranes and rigging and there are no components shared between the units.

x A statement was modified in PSAR Section 9.8.4.2, Design Bases, to state that Consistent with PDC 4, safety-related SSCs are protected from the dynamic effects potentially created by the failure of the crane and rigging equipment.

x A statement was modified in PSAR Section 9.8.4.3, System Evaluation, to state that Design features are include in the plant design so that failure of the lifting device does not interfere or preclude the ability of a safety-related system to perform a safety function.

x A second statement was modified in PSAR Section 9.8.4.3 to clarify that heavy loads would only be moved over safety-related equipment when the reactor is shutdown and the consequences of a load drop had been determined to not pose a safety concern.

The above changes clarify that the overall plant design protects safety-related equipment from the potential effects of crane or rigging malfunctions. Since the cranes and associated rigging may be used to move heavy equipment in proximity to safety-related SSCs, protection against dynamic effects potentially created by the malfunction of the crane or rigging equipment is necessary to conform with PDC 4. The reactor building cranes and rigging do not perform safety-related functions, and the cranes and rigging do not include design features intended to prevent malfunctions that result in a heavy load drop. Rather, administrative controls and interlocks prevent the crane from moving heavy loads over safety-related SSCs except when (1) the reactor is shut down and (2) the consequences of a potential load drop have been determined to neither damage stored irradiated fuel to the extent that a significant off-site release would occur, nor preclude operation of sufficient equipment to achieve safe shutdown.

Additionally, each unit having its own reactor building crane in separate reactor buildings will prevent one crane failure from affecting both units. Based on the above, the staff finds that each unit having its own cranes and rigging, and the changes to PSAR Sections 9.8.4.2 and 9.8.4.3 described above, are acceptable.

On the basis of its review, the staff finds that the level of detail provided regarding the Hermes 2 reactor building cranes and rigging demonstrates an adequate basis for a preliminary design and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.7, for auxiliary systems to not cause accidents to the reactor, uncontrolled release of radioactivity, or interfere with safe shutdown of the reactor.

9.8.4.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the preliminary plant design is sufficient to protect safety-related equipment from dynamic effects that could result from crane operations and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. A more detailed evaluation of the dynamic effects that could result from crane operations, and an evaluation of these effects against the final design, will occur during the review of the Hermes 2 OL application, at which time the staff will confirm that the final design conforms to this design basis.

9.8.5 Auxiliary Site Services

9.8.5.1 Introduction

Section 9.8.5, Auxiliary Site Services, of the Hermes 2 PSAR states that the Hermes 2 auxiliary site services include non-safety related systems and equipment that support operation of the plant, such as machine shops, chemistry laboratory, sewers, lighting, warehousing, and storage. The auxiliary services are not credited for the mitigation of postulated events and will be built so that they will not interfere with the ability of safety-related SSCs to perform their safety function(s). Some site services are proposed to be shared between Unit 1 and Unit 2.

Warehouses, fire water storage, facility lighting, storm and sanitary sewers, and ground water monitoring wells are expected by Kairos to be shared by both the Hermes 1 and Hermes 2 facilities.

9.8.5.2 Regulatory Evaluation

The staff reviewed Section 9.8.5.2, Regulatory Evaluation, of the Hermes 1 SE for applicability to the Hermes 2 SE. Based on the similarities between the Hermes 1 and Hermes 2 facility designs and the consistency of the auxiliary site services between Hermes 1 and Hermes 2, the staff finds that the regulations and guidance listed in Section 9.8.5.2 of the Hermes 1 SE are applicable to Hermes 2. Therefore, this section incorporates by reference Section 9.8.5.2 of the Hermes 1 SE.

9.8.5.3 Technical Evaluation

The staff reviewed Section 9.8.5 of the Hermes 2 PSAR and compared it to the equivalent section in the Hermes 1 PSAR (Section 9.8.5, Auxiliary Site Services). The staff found that Section 9.8.5 of the Hermes 2 PSAR contains information consistent with that in the Hermes 1 PSAR, except for the minor change evaluated below. The staff also verified that the Hermes 2 auxiliary site services remain identical to Hermes 1. Based on these consistencies, this section incorporates by reference Section 9.8.4.3 of the Hermes 1 SE.

9.8.5.3.1 Minor Change Compared to the Hermes 1 PSAR

The minor change in Hermes 2 PSAR Section 9.8.5, as compared to the information in Hermes 1 PSAR Section 9.8.5, is the following:

x Some site services are shared between Unit 1 and Unit 2. Warehouses, fire water storage, facility lighting, storm and sanitary sewers, and ground water monitoring wells are expected to be shared across the site.

In Hermes 2 PSAR Section 9.8.5, Kairos states that Unit 1 and Unit 2 will share some auxiliary site services and other auxiliary site services (e.g., warehouses, fire water storage, facility lighting, storm and sanitary sewers, and ground water monitoring wells) will be shared between the Hermes 1 and Hermes 2 facilities. The auxiliary site services are not used to perform or support safety-related functions, so the sharing of these auxiliary services does not affect the safety of the facilities. Based on the above, the staff find that sharing of auxiliary services between the units and across the site is acceptable.

On the basis of its review, the staff finds that the level of detail provided regarding the Hermes 2 auxiliary services demonstrates an adequate basis for a preliminary design and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.7, for auxiliary systems to not cause accidents to the reactor, uncontrolled release of radioactivity, or interfere with safe shutdown of the reactor.

9.8.5.4 Conclusion

Based on the staff findings above, and as incorporated by reference from the Hermes 1 SE, the staff concludes that the preliminary design of the auxiliary site services is sufficient and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 50.40. A more detailed evaluation of the auxiliary site services will occur during the review of the Hermes 2 OL application, at which time the staff will confirm that the final design conforms to this design basis.

9.9 Power Generation System

The PGS consists of the following systems:

x Steam system x Turbine generator system x Feedwater and condensate system

The purpose of the PGS is to convert the heat energy contained within the IHTS into electrical energy. The PGS does not perform any safety-related functions and the majority of the PGS is shared between Unit 1 and Unit 2.

9.9.1 Steam System

9.9.1.1 Introduction

Section 9.9.1, Steam System, of the Hermes 2 PSAR states that the steam system uses heat from the IHTS salt to generate superheated steam for the turbine generator system for power generation. Each unit contains a superheater in the portion of the reactor building that is not safety-related. The output of the superheater passes through a unit-specific isolation valve into a common steam header that supplies the turbine generator system and recirculated steam for evaporation of condensate. The turbine generator system, the feedwater and condensate system, and shared components of the steam system are outside the reactor buildings.

Saturated steam from a shared evaporator feeds the superheater.

The steam system is not safety-related and is not credited for the mitigation of postulated events. The steam system provides heat removal during normal operations through the power conversion system. The unit-specific main steam isolation valves upstream of the common superheater outlet header support single unit operation as needed. The steam system is designed to handle a turbine trip without a corresponding reactor trip via the turbine bypass line, condenser (which is sized to handle 100% steam load), and steam relief valves (which have the capability to reject 100% load to the atmosphere). The steam system is designed in accordance with industry codes and standards for piping and pressure vessels.

9.9.1.2 Regulatory Evaluation

The applicable regulatory requirements for the evaluation of the Hermes 2 facility steam system are:

x 10 CFR 50.34, Contents of applications; technical information o 10 CFR 50.34(a)(3)(ii) requires that a CP application PSAR include, The design bases and the relation of the design bases to the principal design criteria.

o 10 CFR 50.34(a)(3)(iii) requires that a CP application PSAR include, Information relative to materials of construction, general arrangement, and approximate dimensions, sufficient to provide reasonable assurance that the final design will conform to the design bases with adequate margin for safety.

o 10 CFR 50.34(a)(4) which requires, in part, that a CP application PSAR include, A preliminary analysis and evaluation of the design and performance of structures, systems, and components [SSCs] of the facility x 10 CFR 50.35 x 10 CFR 50.40

The staff did not evaluate whether the requirements in 10 CFR Part 20 would be met for the construction of the Hermes 2 facility. Instead, the staff assessed whether Kairos identified the relevant requirements for an operating facility and provided descriptions of the preliminary facility design. The staff assessed this to determine whether the PSAR provides an acceptable basis for the development of systems and whether there is reasonable assurance that Kairos will comply with the regulations in 10 CFR Part 20 during Hermes 2 facility operation.

Guidance for this review includes:

x NUREG-1537, Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors, Parts 1 and 2, Section 9.7, provides review criteria and procedures.

9.9.1.3 Technical Evaluation

PDC applicable to the steam system are:

x PDC 4, Environmental and dynamic effects design bases x PDC 60, Control of releases of radioactive materials to the environment x PDC 64, Monitoring radioactivity releases

Section 9.9.1 of the PSAR provides a summary description of the steam system and identifies design features of the facility that support the system design function, prevent uncontrolled releases of radioactivity, and prevent interactions that could interfere with or prevent safe shutdown or cause a reactor accident. The steam system removes heat from the IHTS and transfers the superheated steam to the turbine generator for power generation or alternative heat rejection paths either directly to the main condenser or to atmosphere. Tritium produced in the reactor could propagate through the PHTS and IHTS to the steam system, and the steam system preliminary design includes features to control and monitor releases to the atmosphere.

The proposed Hermes 2 facility includes design features that prevent steam system malfunctions from adversely affecting safety-related equipment, which reasonably ensures those malfunctions would not result in reactor accidents; uncontrolled releases of radioactivity; or interference with, or prevention of, safe shutdown of the reactor.

A portion of the steam system, including each units superheater and steam isolation valve, are located in the non-safety related portion of each reactor building. The steam piping is not located near safety-related SSCs. Section 9.9.1 of the PSAR states that safety-related SSCs located inside the safety-related portion of the reactor building are protected from the effects of high-pressure steam line breaks by protective features (e.g., barriers or blowout panels),

qualified for the environmental conditions, provided with sufficient separation, or a combination of these measures. Because of these design features, staff finds that the preliminary design of the facility is consistent with PDC 4 for ensuring that safety-related SSCs are able to withstand the effects of steam system malfunctions and accidents.

The steam system interfaces with the IHTS through the superheater. Tritium formed in the reactor and transported by the PHTS to the IHTS could migrate across the superheater tubes and remain present in the blowdown flow from the evaporator. This fluid, along with feedwater and condensate drains, is directed to the flash vessel where recirculated superheated steam evaporates the fluid for release to the atmosphere through a monitored vent. The preliminary steam system design also includes radioactivity monitoring capability at the steam system relief valves. Therefore, the design of the steam system conforms with PDC 60 and 64 with respect to controlling the release of tritium to the environment and monitoring releases of radioactive material. These design features support development of programs at OL application stage to satisfy the requirements of 10 CFR Part 20.

The staff observed that Kairos postulated multiple initiating events involving the rupture of steam system components. The potential positive reactivity insertion resulting from a steam line break is addressed in Hermes 2 PSAR Section 13.1.2, Insertion of Excess Reactivity. A rupture of a tube within the superheater that results in steam intrusion into the IHTS is discussed in Hermes 2 PSAR Section 13.1.10.11, IHX Failure Due to Superheater Tube Rupture or Leak.

The effect of this event on the IHTS is addressed in Hermes 2 PSAR Section 5.2, Intermediate Heat Transport System. These initiating events are addressed in SE Sections 13.1.2, Insertion of Excess Reactivity, 13.1.10.11, IHX Failure Due to Superheater Tube Rupture or Leak, and 5.2, Intermediate Heat Transport System, respectively.

On the basis of its review, the staff finds that the level of detail provided regarding the Hermes 2 steam system demonstrates an adequate basis for a preliminary design; meets PDC 4, 60, and 64; and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.7, in that potential malfunctions should not result in reactor accidents, uncontrolled releases of radioactivity, or interfere with or prevent safe shutdown of the reactor.

9.9.1.4 Conclusion

Based on the staffs findings above, the staff concludes that the preliminary design of the facility is sufficient with respect to the steam system and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. A more detailed evaluation of the steam system design will occur during the review of the Hermes 2 OL application, at which time the staff will confirm that the final design conforms to this design basis.

9.9.2 Turbine Generator System

9.9.2.1 Introduction

Section 9.9.2, Turbine Generator System, of the Hermes 2 PSAR states that the turbine generator system converts thermal energy in the steam to electrical energy. One turbine generator building and one turbine generator are shared between Unit 1 and Unit 2. The turbine generator system interfaces with the steam system and the condensate and feedwater system.

The turbine generator system is not safety-related and is not credited for the mitigation of postulated events.

9.9.2.2 Regulatory Evaluation

The applicable regulatory requirements for the evaluation of the Hermes 2 test reactor turbine generator system are:

x 10 CFR 50.34 o 10 CFR 50.34(a)(3)(ii) requires that a CP application PSAR include, The design bases and the relation of the design bases to the principal design criteria.

o 10 CFR 50.34(a)(3)(iii) requires that a CP application PSAR include, Information relative to materials of construction, general arrangement, and approximate dimensions, sufficient to provide reasonable assurance that the final design will conform to the design bases with adequate margin for safety.

o 10 CFR 50.34(a)(4) which requires, in part, that a CP application PSAR include, A preliminary analysis and evaluation of the design and performance of structures, systems, and components [SSCs] of the facility x 10 CFR 50.35 x 10 CFR 50.40

Guidance for this review includes:

x NUREG-1537, Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors, Parts 1 and 2, Section 9.7, provides review criteria and procedures.

9.9.2.3 Technical Evaluation

The PDC applicable to the turbine generator is PDC 4, which specifies that safety-related equipment shall be appropriately protected from the dynamic effects of equipment malfunctions, including missiles.

Section 9.9.2 of the Hermes 2 PSAR describes that the turbine generator converts thermal energy in the steam to electrical energy in the turbine generator building. The turbine generator building is separate from the reactor buildings and the safety-related equipment located within those buildings. Also, the turbine generator is favorably oriented with respect to safety-related equipment located in the reactor buildings such that missiles resulting from postulated turbine generator malfunctions would not be able to adversely affect the ability of the safety-related equipment to perform their safety functions. Because of these design features, staff finds that the preliminary design of the facility is consistent with PDC 4 for safety-related SSCs to be appropriately protected against the dynamic effects of turbine generator system malfunctions.

Therefore, these design features reasonably ensure that turbine generator system malfunctions would not result in reactor accidents, uncontrolled releases of radioactivity, or interference with or prevention of safe shutdown of the reactor.

On the basis of its review, the staff finds that the level of detail provided regarding the Hermes 2 turbine generator system demonstrates an adequate basis for a preliminary design, meets PDC 4, and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.7, in that potential malfunctions should not result in reactor accidents, uncontrolled release of radioactivity, or interfere with or prevent safe shutdown of the reactor.

9.9.2.4 Conclusion

Based on the staffs findings above, the staff concludes that the preliminary design of the facility is acceptable with respect to design and location of the turbine generator system and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. A more detailed evaluation of the turbine generator system design will occur during the review of the Hermes 2 OL application, at which time the staff will confirm that the final design conforms to this design basis.

9.9.3 Condensate and Feedwater System

9.9.3.1 Introduction

Section 9.9.3, Condensate and Feedwater System, of the Hermes 2 PSAR states that the condensate and feedwater system returns condensed steam from the air-cooled condenser to the condensate tank, deaerates, reheats the water to feedwater temperature and pressure, and supplies feedwater to the evaporator. The air-cooled condenser is sized to handle 100 percent of the steam flow from the turbine bypass system, which permits the power conversion system to withstand a turbine trip without requiring corresponding reactor trips. The condensate and feedwater system includes radiation monitors on the air-cooled condenser and deaerator vapor vents which monitor tritium releases to the atmosphere during normal operations. The condensate and feedwater system is not safety-related and is not credited for the mitigation of postulated events. As shown in Hermes 2 PSAR Table 3.6-2, Design and Construction Codes and Standards for Fluid Systems, the condensate and feedwater system is designed in accordance with industrial standards for piping and pressure vessels.

9.9.3.2 Regulatory Evaluation

The applicable regulatory requirements for the evaluation of the Hermes 2 test reactor condensate and feedwater system are:

x 10 CFR 50.34 o 10 CFR 50.34(a)(3)(ii) requires that a CP application PSAR include, The design bases and the relation of the design bases to the principal design criteria.

o 10 CFR 50.34(a)(3)(iii) requires that a CP application PSAR include, Information relative to materials of construction, general arrangement, and approximate dimensions, sufficient to provide reasonable assurance that the final design will conform to the design bases with adequate margin for safety.

o 10 CFR 50.34(a)(4) which requires, in part, that a CP application PSAR include, A preliminary analysis and evaluation of the design and performance of structures, systems, and components [SSCs] of the facility x 10 CFR 50.35 x 10 CFR 50.40

The staff did not evaluate whether the requirements in 10 CFR Part 20 would be met for the construction of the Hermes 2 facility. Instead, the staff assessed whether Kairos identified the relevant requirements for an operating facility and provided descriptions of the preliminary facility design. The staff assessed this to determine whether the PSAR provides an acceptable basis for the development of systems and whether there is reasonable assurance that Kairos will comply with the regulations in 10 CFR Part 20 during Hermes 2 facility operation.

Guidance for this review includes:

x NUREG-1537, Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors, Parts 1 and 2, Section 9.7, provides review criteria and procedures.

9.9.3.3 Technical Evaluation

PDC applicable to the condensate and feedwater system are:

x PDC 4, Environmental and dynamic effects design bases x PDC 60, Control of releases of radioactive materials to the environment x PDC 64, Monitoring radioactivity releases

Section 9.9.3 of the Hermes 2 PSAR provides a summary description of the condensate and feedwater system and identifies design features of the facility that support the system design function, prevent uncontrolled releases of radioactivity, and prevent interactions that could interfere with or prevent safe shutdown or cause a reactor accident.

The condensate and feedwater system is located in the turbine generator building, which is separate from the reactor buildings and the safety-related equipment located within those buildings. Because of these design features, staff finds that the preliminary design of the facility is consistent with PDC 4 for safety-related SSCs to be appropriately protected against the dynamic effects of pipe breaks and malfunctions affecting the condensate and feedwater system.

Tritium formed in the reactor and transported by the PHTS and IHTS to the steam system could be exhausted from the turbine into the condenser or be directed into the deaerator. These components include vents for controlled release of gases potentially containing tritium into the atmosphere. The preliminary feedwater and condensate system design includes radioactivity monitoring capability at the condenser and deaerator vents. Therefore, the preliminary design of the feedwater and condensate system conforms with PDC 60 and PDC 64 with respect to controlling the release of tritium to the environment and monitoring releases of radioactive material. These design features support development of programs at the OL application stage to satisfy the requirements of 10 CFR Part 20.

On the basis of its review, the staff finds that the level of detail provided regarding the Hermes 2 condensate and feedwater system demonstrates an adequate basis for a preliminary design, meets PDC 4, 60, and 64; and satisfies the applicable acceptance criteria of NUREG-1537, Part 2, Section 9.7, in that potential malfunctions should not result in reactor accidents, uncontrolled releases of radioactivity, or interfere with or prevent safe shutdown of the reactor.

9.9.3.4 Conclusion

Based on the staffs findings above, the staff concludes that the preliminary design of the facility is sufficient with respect to the condensate and feedwater system and meets the applicable regulatory requirements and guidance identified in this section for the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40. A more detailed evaluation of the condensate and feedwater system design will occur during the review of the Hermes 2 OL application, at which time the staff will confirm that the final design conforms to this design basis.

9.10 Summary and Conclusions for Auxiliary Systems

The staff evaluated the information on the Hermes 2 auxiliary systems as described in PSAR Chapter 9 and finds that the preliminary information on, and design criteria of, the auxiliary systems, including the PDC, design bases, and other design information: (1) provide reasonable assurance that the final design will conform to the design bases, (2) meet all applicable regulatory requirements, and (3) meet the applicable acceptance criteria in NUREG-1537, Part 2, allowing the staff to make findings that:

x Kaiross preliminary information and commitments to design the reactor coolant auxiliary systems, RBHVAC systems, PHSS, communication systems, water systems, other auxiliary systems, and PGS are sufficient and meet the applicable regulatory requirements and guidance for the issuance of CPs. Further information on these items can reasonably be left for later consideration in the OL application.

x The preliminary information on fire protection systems and programs is sufficient and meets the applicable regulatory requirements and guidance for the issuance of CPs.

Further information can reasonably be left for later consideration in the final safety analysis report, fire protection program, and fire hazards analysis that will be submitted with an OL application.

x The preliminary design of the Kairos program and auxiliary facilities for the possession and use of byproduct material, source material, and SNM at Hermes 2 is sufficient and meets the applicable regulatory requirements and guidance for the issuance of CPs.

Further information related to possession and use of byproduct material, source material, and SNM during operations and decommissioning can reasonably be left for later consideration during future reviews of a Hermes 2 OL application and proposed decommissioning plan, respectively.

Based on these findings referenced above, the staff concludes the following regarding the issuance of CPs in accordance with 10 CFR 50.35 and 10 CFR 50.40:

x Kairos has described the proposed design of the auxiliary systems, including, but not limited to, the principal architectural and engineering criteria for the design, and has identified the major features or components incorporated therein for the protection of the health and safety of the public.

x Such further technical or design information as may be required to complete the safety analysis, and which can reasonably be left for later consideration, will be supplied in the final safety analysis report.

x Safety features or components which require research and development have been described by Kairos and a research and development program (see SE Section 1.1.5, Ongoing Research and Development) will be conducted that is reasonably designed to resolve any safety questions associated with such features or components.

x There is reasonable assurance that safety questions will be satisfactorily resolved at or before the latest date stated in the application for completion of construction of the proposed facility.

x There is reasonable assurance: (i) that the construction of the Hermes 2 facility will not endanger the health and safety of the public, and (ii) that construction activities can be conducted in compliance with the Commissions regulations.

x The issuance of permits for the construction of the Hermes 2 facility would not be inimical to the common defense and security or to the health and safety of the public.

9.11 References for Auxiliary Systems

American Institute of Steel Construction (AISC) N690-18, Specification for Safety-Related Steel Structures for Nuclear Facilities, AISC: Randolph Street, Chicago, IL. June 2018.

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. AISC 370-21, Specification for Structural Stainless Steel Buildings, June 2021.

American Society of Civil Engineers (ASCE) 43-19, Seismic Design Criteria for Structures, Systems, and Components in Nuclear Facilities, Alexander Bell Drive, Reston, VA. January 2021.

American Society of Mechanical Engineers (ASME) BTH-1-2020, Design of Below-the-Hook Lifting Devices, ASME: Two Park Avenue, New York, NY. January 2017.

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. ASME NOG-1-2020, Rules for Construction of Overhead and Gantry Cranes (Top Running Bridge, Single or Multiple Girder, Top Running Trolley Hoist), December 2020.

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. ASME B30.2 -2016, Overhead and Gantry Cranes (Top Running Bridge, Single or Multiple Girder, Top Running Trolley Hoist), May 2017.

American Society for Testing and Materials (ASTM) A240, Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications, ASTM: Harbor Drive, West Conshohocken, PA. December 2022.

Kairos Power LLC, Reactor Coolant for the Kairos Power Fluoride Salt-Cooled High Temperature Reactor Topical Report, KP-TR-005-P-A, Revision 1, July 2020, ADAMS No.

ML20219A591.

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. Principal Design Criteria for the Kairos Power Fluoride Salt-Cooled, High Temperature Reactor, KP-TR-003-NP-A, Revision 1, June 2020, ADAMS No. ML20167A174.

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. Transmittal of Kairos Power CPA Changes, February 2022, ADAMS No. ML22049B555.

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. Transmittal of Changes to Hermes Construction Permit Application, February 2022, ADAMS No. ML22042A095.

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. Transmittal of Changes to PSAR Sections 9.1.1 and 9.1.4, June 2022, ADAMS No.

ML22160A689.

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. Transmittal of Responses to NRC Requests for Confirmation of Information Hermes Preliminary Safety Analysis Report, Section 9.1, August 2022, ADAMS No. ML22231B228.

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. Submittal of the Preliminary Safety Analysis Report for the Kairos Power Fluoride Salt-Cooled, High Temperature Non-Power Reactor (Hermes), Revision 3, May 31, 2023, ADAMS Pkg. ML23151A743.

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. Kairos Power Response to Hermes 2 General Audit Question 1.5-2, October 27, 2023, ADAMS No. ML23300A144.

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. Submittal of the Preliminary Safety Analysis Report for the Kairos Power Fluoride Salt-Cooled, High Temperature Non-Power Reactor (Hermes 2), Revision 1, [month] xx, 2024, ADAMS Pkg. MLxxxxxxxxx.

Nuclear Regulatory Commission (U.S.) (NRC). NUREG-1537 Part 2, Guidelines for Preparing and Reviewing Application for the Licensing of Non-Power Reactors, Parts 1 and 2. NRC:

Washington, D.C. February 1996, ADAMS Accession Nos. ML042430055 and ML042430048.

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. Regulatory Guide 4.20, Constraint on Releases of Airborne Radioactive Materials to the Environment for Licensees Other Than Power Reactors, Revision 1, April 2012, ADAMS No.

ML110120299.

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. Regulatory Guide 1.243, Safety-Related Steel Structures and Steel-Plate Composite (SC)

Walls for other than Reactor Vessels and Containments, August 2021, ADAMS No.

ML21089A032.

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. Regulatory Guide 1.244, Control of Heavy Loads at Nuclear Facilities, December 2021, ADAMS No. ML21006A346.

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. Summary Report for the Regulatory Audit of Kairos Power LLC Hermes Construction Permit Preliminary Safety Analysis Report - General Audit, June 2023, ADAMS No.

ML23160A287.

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. Safety Evaluation for the Kairos Power LLC Construction Permit Application for the Hermes Non-Power Test Reactor, June 16, 2023, ADAMS Pkg. ML23158A265.

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. Summary Report for the Regulatory Audit of Kairos Power LLC Hermes 2 Construction Permit Preliminary Safety Analysis Report - General Audit, [month] xx, 2024, ADAMS No.

MLxxxxxxxxx.