ML25220A105
| ML25220A105 | |
| Person / Time | |
|---|---|
| Site: | 99902100 |
| Issue date: | 08/08/2025 |
| From: | Joshua Borromeo NRC/NRR/DANU/UAL1 |
| To: | George Wilson TerraPower |
| References | |
| EPID L-2024-TOP-0006 | |
| Download: ML25220A105 (1) | |
Text
August 8, 2025 George Wilson Senior Vice President, Regulatory Affairs TerraPower, LLC 15800 Northup Way Bellevue, WA 98008
SUBJECT:
TERRAPOWER, LLC - FINAL SAFETY EVALUATION OF NAT-4950, INSTRUMENTATION & CONTROL ARCHITECTURE AND DESIGN BASIS TOPICAL REPORT, REVISION 2 (EPID NO. L-2024-TOP-0006)
Dear George Wilson:
By letter dated March 7, 2024, TerraPower, LLC (TerraPower) submitted Topical Report (TR) NAT-4950 Revision 1, Instrumentation & Control Architecture and Design Basis Topical Report (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24068A186) to the U.S. Nuclear Regulatory Commission (NRC) staff which contains an overview of the instrumentation and control (I&C) architecture and design basis for the proposed Natrium plant. The TR also addresses the associated design basis and the process for I&Cs relationship to lines of defense, structure, system, and component classification, and I&C functions basis and allocation to individual systems. On April 15, 2024, the NRC staff found that the material presented in the TR provided technical information in sufficient detail to enable the NRC staff to begin its detailed technical review (ML24101A204).
On June 24, 2024, the NRC staff transmitted an audit plan to TerraPower (ML24163A003) and subsequently conducted an audit of materials related to the TR from July 8, 2024, to September 30, 2024. The audit summary report was issued on March 7, 2025 (ML25015A128). On October 30, 2024, TerraPower submitted a revision of the TR (ML24305A009) to clarify portions of the TR as discussed in the audit summary.
The enclosed final Safety Evaluation (SE) is being provided to TerraPower, because the NRC staff has found NAT-4950, Revision 2, acceptable for referencing in licensing actions to the extent specified and under the limitations and conditions delineated in the TR and the SE. The final SE defines the basis for the NRC staffs acceptance of the TR.
The NRC staff requests that TerraPower submit to NRC staff an approved version of this TR within three months of receipt of this letter. The approved version should incorporate this letter and the enclosed SE after the title page. The approved version should include a -A (designating approved) following the TR identification symbol.
If you have any questions regarding this matter, please contact Roel Brusselmans at (301) 415-0829 or via email at Roel.Brusselmans@nrc.gov.
Sincerely,
/RA/
Joshua Borromeo, Chief Advanced Reactor Licensing Branch 1 Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation Project No.: 99902100
Enclosure:
As stated cc: TerraPower Natrium via GovDelivery
Pkg: ML25220A104 Letter: ML25220A105 Enclosure (Public): ML25220A106 NRR-043 OFFICE NRR/DEX/EICB:TR NRR/DEX/EICB:BC NRR/DANU/UAL1:PM NAME DTaneja FSacko RBrusselmans DATE 7/25/2025 7/25/2025 7/25/2025 OFFICE NRR/DANU/UAL1:LA OGC:NLO NRR/DANU/UAL1:BC NAME DGreene JEzell JBorromeo DATE 7/30/2025 8/1/2025 8/4/2025 OFFICE NRR/DANU/UAL1:PM NAME RBrusselmans DATE 8/4/2025