ML23117A017
| ML23117A017 | |
| Person / Time | |
|---|---|
| Site: | 99902069, Hermes |
| Issue date: | 04/27/2023 |
| From: | Charles Brown Advisory Committee on Reactor Safeguards |
| To: | David Petti Advisory Committee on Reactor Safeguards |
| References | |
| Download: ML23117A017 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS WASHINGTON, DC 20555 - 0001 April 27, 2023 MEMORANDUM TO: David Petti, Lead Kairos Power Licensing Subcommittee Advisory Committee on Reactor Safeguards FROM: Charles Brown, Member /RA/
Advisory Committee on Reactor Safeguards
SUBJECT:
INPUT FOR ACRS REVIEW OF KAIROS NON-POWER REACTOR HERMES CONSTRUCTION PERMIT APPLICATION - DRAFT SAFETY EVALUATION FOR CHAPTER 8, ELECTRIC POWER SYSTEMS In response to the Subcommittees request, I have reviewed the NRC staffs draft safety evaluation (SE) with no open items, and the associated section of the applicants Preliminary Safety Analysis Report (PSAR), for Chapter 8, Electric Power Systems, Revision 0. I also reviewed selected parts of Revision 2 to confirm my conclusion for this memorandum. The following is my recommended course of action concerning further review of this chapter and the staffs associated safety evaluation.
Background
Chapter 8 of the SE documents the staffs review of the Kairos Power LLC (Kairos) Hermes construction permit of the preliminary design of the Hermes non-power test reactor structures, systems, and components (SSCs) as presented in Chapter 8, Electric Power Systems, of the Hermes PSAR. The Hermes construction permit application purpose is to test and demonstrate the key technologies, design features, and safety functions of the Kairos Power-FHR technology and its SSCs.
SE Summary The staff SE evaluated and documented descriptions and discussions of Hermes PSARs Electric Power System. The staff reviewed Hermes PSAR Chapter 8 against applicable regulatory requirements using regulatory guidance and standards to assess the sufficiency of the preliminary design of the Hermes facility. Hermes PSAR Section 8.1, Summary Description, states that the purpose of the electrical system is to provide power to plant equipment for operation and that the electrical system consists of the non-Class 1E normal power system and the backup power system. Further, Kairos states that, due to the passive design of Hermes, safety-related structures, systems, and components (SSCs) do not require electric power to perform safety-related functions following a design basis event. The design does not have any emergency electrical power systems as described in NUREG-1537, Part 2, Section 8.2. In addition, Kairos states that alternating current (AC) power from off-site or backup power sources is not required to mitigate a design basis event.
D. Petti Discussion The Hermes Electric Power System is comprised of three parts, The primary grid power source, the Normal Power System, and the Backup Power System. The architectural design of the system identifies the interconnection interfaces between the three parts and the configuration between the parts and their associated subsystems. PSAR Figure 8.1-1, Electrical Configuration Diagram, provides an overview of the interconnections of the three parts and individual subsystems. Kairos states that owing to the passive design of Hermes, none of SSCs require electrical power to perform safety-related functions following a postulated event.
The primary grid power source consists of a single incoming feeder from the utility with a nominal feeder voltage of 4.16 kilovolt (kV), and a 4.16 kV/480 V step down transformer which feeds an automatic transfer switch to the normal power system bus.
The backup power source consists of backup 480 V generators driven by a fuel source yet to be determined and supporting subsystems and a portable generator connection both of which serve as an alternate feed to the automatic transfer switch. The backup generators start automatically upon loss of the utility power source.
The Normal Power System bus then feeds the Plant Control System, the Reactor Protection System, the Remote Onsite Shutdown Panel, Main Control Room, and Emergency Lighting and Communications loads through multiple 120V AC Uninterruptible Power Supplies each having a 72-hour capacity.
The NRC staff found that the descriptions and discussions of Kairos Chapter 8 Electric Power System are sufficient and meet the applicable regulatory requirements and guidance, and acceptance criteria, for the issuance of a construction permit.
Concerns I did not identify any specific deficiencies during my review.
Recommendation As lead reviewer for Hermes PSAR Chapter 8 and staff SE, I do not have any specific recommendations at this stage on the Hermes PSAR and staff review.
References
- 1. USNRC, Draft Safety Evaluation for Hermes NonPower Reactor Preliminary Safety Analysis Report Chapter 8, January 2023 (ML23017A120)
- 2. Kairos Power LLC, Submittal of the Preliminary Safety Analysis Report for the Kairos Power Fluoride Salt-Cooled, High Temperature Non-Power Reactor (Hermes), Revision 2, February 2023 (ML23055A672)
- 3. USNRC, NUREG-1537, Part 1, Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors, Format and Content, February 1996 (ML042430055)
D. Petti 4. USNRC, NUREG-1537, Part 2, Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors, Standard Review Plan and Acceptance Criteria, February 1996 (ML042430048)
D. Petti April 27, 2023
SUBJECT:
INPUT FOR ACRS REVIEW OF KAIROS NON-POWER REACTOR HERMES CONSTRUCTION PERMIT APPLICATION - DRAFT SAFETY EVALUATION FOR CHAPTER 8, ELECTRIC POWER SYSTEMS Package No: ML23117A000 Memo Accession No: ML23117A017 Publicly Available Y Sensitive N Viewing Rights: NRC Users or ACRS Only or See Restricted distribution *via e-mail OFFICE ACRS/TSB* SUNSI Review* ACRS/TSB* ACRS*
NAME WWang WWang LBurkhart CBrown DATE 4/27/2023 4/27/2023 4/27/2023 4/27/2023 OFFICIAL RECORD COPY