ML25261A323
| ML25261A323 | |
| Person / Time | |
|---|---|
| Site: | Kemmerer File:TerraPower icon.png |
| Issue date: | 08/27/2025 |
| From: | Joshua Borromeo Office of Nuclear Reactor Regulation |
| To: | George Wilson TerraPower |
| Shared Package | |
| ML25261A322 | List: |
| References | |
| EPID L-2025-LRO-0000 | |
| Download: ML25261A323 (1) | |
Text
August 27, 2025 George Wilson Senior Vice President, Regulatory Affairs TerraPower, LLC 15800 Northup Way Bellevue, WA 98008
SUBJECT:
TERRAPOWER, LLC - U.S. NUCLEAR REGULATORY COMMISSION STAFF FEEDBACK REGARDING WHITE PAPER: REGULATORY INTERPRETATION OF THE APPLICABILITY OF 10 CFR 50.10 AND 10 CFR 51.4 DEFINITIONS OF ACTIVITIES CONSTITUTING CONSTRUCTION TO THE INSTALLATION OF CONDUIT AND CABLE TRAYS, REVISION 0 (EPID NO. L-2025-LRO-0000)
Dear George Wilson:
By letter dated January 3, 2025 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML25003A162), TerraPower, LLC (TerraPower), on behalf of US SFR Owner, LLC (USO), submitted a white paper (WP) titled Regulatory Interpretation of the Applicability of 10 CFR 50.10 and 10 CFR 51.4 Definitions of Activities Constituting Construction to the Installation of Conduit and Cable Trays, Revision 0, for the U.S. Nuclear Regulatory Commission (NRC) staffs review. The NRC staff was requested to review this paper and provide feedback. The NRC staff has completed its review of the submittal. The enclosure of this letter provides the NRC staffs feedback and observations on the WP.
If you have questions about 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 Docket No.: 50-0613
Enclosure:
As stated cc: TerraPower Natrium via GovDelivery
ML25261A323 OFFICE NSIR/DPCP/RPPB/TR NSIR/DPCP/RPPB/BC NRR/DANU/UAL1:TR/PM NAME TLeach AMarshall RBrusselmans DATE 3/25/2025 4/21/2025 4/22/2025 OFFICE NRR/DANU/UAL1:LA NRR/DANU/UAL1:BC NRR/DANU/UAL1:PM NAME DGreene JBorromeo RBrusselmans DATE 5/7/2025 8/26/2025 8/27/2025
3 OFFICE OF NUCLEAR REACTOR REGULATION RESPONSE TO TERRAPOWER, LLC REQUEST FOR INTERPRETATION OF 10 CFR 50.10 AND 10 CFR
51.4 INTRODUCTION
By letter dated January 3, 2025 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML25003A162), TerraPower, LLC (TerraPower), on behalf of US SFR Owner, LLC (USO), submitted a white paper (WP) titled Regulatory Interpretation of the Applicability of 10 CFR 50.10 and 10 CFR 51.4 Definitions of Activities Constituting Construction to the Installation of Conduit and Cable Trays, Revision 0, for the U.S. Nuclear Regulatory Commission (NRC) staffs review. The letter included TerraPowers assessment of the applicability of 10 CFR 50.10 as it relates to installation of conduit and cable trays for security equipment. The NRC staff was requested to review this paper and provide feedback. The NRC staff has completed its review of the submittal. The enclosure of this letter provides the NRC staffs feedback and observations on the WP.
OVERVIEW OF 10 CFR 50.10 AND 10 CFR 51.4 Construction, in accordance with 10 CFR 51.4, is based around structures, systems, or components (SSCs) that have particular importance such as being safety-related or meeting the security requirements in 10 CFR Part 73. Activities related to the driving of piles, subsurface preparation, placement of backfill, concrete, or permanent retraining walls within an excavation, installation of foundations, or in-place assembly, erection, fabrication, or testing for these specific SSCs are considered construction.
The definition of construction in 10 CFR 50.10 is divided into two parts; it specifies activities deemed to constitute construction and activities which are excluded from the definition.
Construction in 10 CFR 50.10 is defined similarly to 10 CFR 51.4.
Pursuant to 10 CFR 50.10, License required; limited work authorization, paragraph (c), [n]o person may begin the construction of a production or utilization facility on a site on which the facility is to be operated until that person has been issued either a CP... or a limited work authorization[.]
EVALUATION AND CONCLUSION The NRC staff evaluated TerraPowers regulatory applicability assessment taking into consideration the details regarding the proposed conduit and cable trays and Natrium reactor designs. Specifically, the NRC staff evaluated whether construction of the conduit or cable trays meet the definition of construction provided in 10 CFR 50.10(a)(1). The NRC staffs evaluation is summarized as follows:
The regulations in 10 CFR 50.10(a)(1)(i) through (iv) are not applicable because the conduit and cable trays will not fulfill any safety function for the Natrium reactor facility.
The regulation in 10 CFR 50.10(a)(1)(v) is not applicable because, as discussed in TerraPowers assessment, the conduit and cable tray are not part of the Natrium plants physical or cyber security program and as such does not contain any SSCs necessary to
comply with 10 CFR Part 73, Physical Protection of Plants and Materials. For the Natrium design, the primary physical protection for a cable is provided by the insulation, shielding, and jacket. Security cable will consist of appropriately rated armored cable.
Conduit and cable trays provide additional mechanical support and protection. Conduit and cable trays do not provide a transmission pathway for the signal from the security system and are not required for the security system to fulfill its function. Therefore, conduit and cable trays are not part of the structure, system, or component (SSC) of the security system in 10 CFR 73.
The regulation in 10 CFR 50.10(a)(1)(vi) is not applicable because the conduit and cable trays do not contain SSCs needed as part of the plants fire protection system to comply with 10 CFR 50.48, Fire protection, or criterion 3 of 10 CFR Part 50, Domestic Licensing of Production and Utilization Facilities, appendix A, General Design Criteria for Nuclear Power Plants.
The regulation in 10 CFR 50.10(a)(1)(vii) is not applicable because the conduit and cable tray do not involve onsite emergency facilities necessary to comply with the requirements of 10 CFR 50.47, Emergency plans, and 10 CFR Part 50, appendix E, Emergency Planning and Preparedness for Production and Utilization Facilities.
The above evaluation also applies to the related sections of 10 CFR 51.4 that define construction.
Based on this evaluation, the NRC staff offers the following feedback: the installation of conduit and cable trays as described does appear not meet the definition of construction provided in 10 CFR 50.10(a)(1) or 10 CFR 51.4(1) and therefore, a CP or a limited work authorization pursuant to 10 CFR 50.10 would not be required to begin the construction of the conduit or cable trays.
Because the information provided in TerraPowers January 3, 2025, letter is preliminary in nature and does not constitute a license application, the NRC staffs determination does not constitute either a review or approval of the design of the planned conduit or cable trays for the proposed Natrium facility.