ML24255A321

Memo - Summary of Meeting on August 27, 2024 with TRISO-X to Discuss Draft Supplement Responses to Structural Programmatic Requests for Additional Information

ML24255A321
Person / Time
Site:	Triso-X
Issue date:	10/08/2024
From:	Matt Bartlett NRC/NMSS/DFM/FFLB
To:	James Downs NRC/NMSS/DFM/FFLB
Shared Package
ML24255A320	List: ML24255A321 ML24255A323
References
EPID L-2022-PMP-0005
Download: ML24255A321 (1)

Text

OFFICIAL USE ONLY - SECURITY RELATED INFORMATION OFFICIAL USE ONLY - SECURITY RELATED INFORMATION UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 205550001 MEMORANDUM TO:

James Downs, Acting Chief Fuel Facility Licensing Branch Division of Fuel Management Office of Nuclear Material Safety and Safeguards FROM:

Matthew Bartlett, Sr. Project Manager Fuel Facility Licensing Branch Division of Fuel Management Office of Nuclear Material Safety and Safeguards

SUMMARY

OF MEETING ON AUGUST 27, 2024, WITH TRISO-X LLC, TO DISCUSS DRAFT SUPPLEMENT RESPONSES TO STRUCTURAL PROGRAMMATIC REQUESTS FOR ADDITIONAL INFORMATION, (ENTERPRISE PROJECT IDENTIFIER L2022PMP0005)

The U.S. Nuclear Regulatory Commission (NRC) hosted a closed Microsoft Teams meeting with TRISO-X, LLC (TRISO-X) on August 27, 2024, from 11:00 a.m. until 12:30 p.m. The purpose of the meeting was to discuss the draft supplemental responses from TRISO-X to the NRC staff to resolves requests for additional information (RAIs) issued via letter dated November 17, 2023 (Agencywide Documents Access and Management System [ADAMS] Accession No. ML23313A110). TRISO-X provided their initial responses to the RAIs via letter dated December 15, 2023 (ML23349A208), which did not resolve the RAIs.

This meeting involved discussion of the response for Structural RAI 22, (Building) Risk Category. It continues discussions from meetings held on January 24, 2024 (ML24030A847),

April 9, 2024 (ML24102A180), and June 27, 2024 (ML24206A077).

CONTACT: Matt Bartlett, NMSS/DFM 301415-7154 A document transmitted herewith contains Security-Related Information. When separated from, this document and are decontrolled.

October 8, 2024 Signed by Bartlett, Matthew on 10/08/24

OFFICIAL USE ONLY - SECURITY RELATED INFORMATION J. Downs 2

OFFICIAL USE ONLY - SECURITY RELATED INFORMATION TRISO-X posted slides to the online portal1 on August 14, 2024, which was the originally scheduled date for this meeting. The NRC staff rescheduled the meeting to August 27, 2024, to allow additional time to review the new information in the slides, which were subsequently emailed to the NRC, see enclosure 2. The slides proposed a new approach to satisfy the performance requirements of Title 10 of the Code of Federal Regulations (10 CFR) §70.61 and 70.64, which included the following points:

1.

Internal equipment is designated as a critical non-structural components (CNSCs) and items relied on for safety (IROFS) to protect against intermediate or high-consequence events resulting from natural phenomena hazard (NPH) events.

2.

Since TRISO-X is crediting CNSC to mitigate the consequences of NPH events, they do not intend to credit any exterior barriers, such as the building structure.

3.

Because TRISO-X is not intending to rely on the building structures to perform a safety function or meet the performance requirements for 10 CFR 70.61, they believe that designing and constructing in accordance with building risk category III, from American Society of Civil Engineers (ASCE) 7-16, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, is appropriate.

The NRC staff stated that TRISO-X needs to demonstrate their approach for all the credible NPH events for the site. The slides are focused on the seismic NPH. TRISO-X indicated they have that information and would provide it in the future.

As TRISO-X does not believe that the building or structures are needed to meet the performance requirements, they plan to meet the baseline design criteria in 10 CFR 70.64 by meeting the building codes (i.e., building risk category III from ASCE 7-16). The NRC staff agreed in principle that structures not important to safety (i.e., that are not IROFS) could be designed based on an industrial code that does not account for radiological hazards. However, the current application indicates the buildings are relied on for preventing or mitigating potential consequences of NPH events. Therefore, the building structures should use an appropriate code that takes account of the applicable hazards (e.g., radiological, chemical, criticality).

ASCE 43, Seismic Design Criteria for Structures, Systems, and Components in Nuclear Facilities would be appropriate for structures important to safety for a fuel cycle facility. The NRC staff can consider a risk informed approach to allow use of an industrial code such as ASCE 7-16, provided a more robust building risk category IV is used to provide more reliability for the nuclear material hazards.

The NRC staff requested TRISO-X to explain their analysis for determining that NPH events do not result in intermediate or high consequence events. TRISO-X stated that since the building is designed to meet the base line design criteria (BDC) according to the international building codes, the NPH events are highly unlikely. The NRC staff stated that TRISO-X appears to be relying on the design of the building as the engineered mitigation to mitigate the consequences of NPH events. TRISO-X stated they do not understand the staff's statement that they need to evaluate NPH events without considering the design of the building to meet the BDC because the unmitigated state should be based on existing features, which includes the design of the building. The staff pointed out that NPH events are different from process safety events. The likelihood of NPH events is independent of the design. Elements of the design relied on to 1 Documents provided on the portal are internal TRISO-X documents not to be docketed in ADAMS.

OFFICIAL USE ONLY - SECURITY RELATED INFORMATION J. Downs 3

OFFICIAL USE ONLY - SECURITY RELATED INFORMATION mitigate the intermediate and high consequences of NPH events need to be identified as IROFS, consistent with 10 CFR 70.61(e).

For the TRISO-X approach to be acceptable to the NRC staff, TRISO-X would need to demonstrate they are only relying on CNSCs to meet the performance requirements. However, this appears to contradict the TRISO-X statements that meeting the BDC is used to ensure NPH events meet the performance requirements. The NRC staff emphasized that meeting the BDC does not replace the requirement to meet 10 CFR 70.61. TRISO-X stated they believe they have adequately considered the potential accident sequences and are addressing the performance requirements. The NRC staff proposed performing an audit at the TRISO-X site to discuss the issues more in-depth and consider specific examples.

TRISO-X raised concern regarding the timing of the supplemental information, which is currently due August 30, 2024. The NRC staff stated that they support moving the date of the supplement to allow further discuss to reach alignment during the audit, which could be held toward the end of September 2024. The NRC staff stated that they will provide an extension for the supplement due date until several weeks after the audit.

TRISO-X pointed out that the existing guidance provided in NUREG1520, Standard Review Plan for License Applications for Fuel Cycle Facilities, regarding NPH analysis, does not adequately address this topic and is a potential cause for the misalignment between TRISO-X and the NRC staff. The NRC staff acknowledged this comment and will consider it as a potential lesson learned topic for resolution in future updates to the guidance.

A list of participants is provided as Enclosure 1. A copy of the TRISO-X slides is provided in (non-public).

Docket No. 07007027

Enclosures:

1.

Participant List (public) 2.

TRISO-X Slides (non-public) cc: trisox@listmgr.nrc.gov

ML24255A320; Memo ML24255A321 OFFICE NMSS NMSS/DFM/FFLB* NMSS/DFM/FFLB NMSS/DFM/FFLB NAME JRudd SPoy MBartlett JGoodridge DATE Sep 12, 2024 Sep 18, 2024 Sep 19, 2024 Sep 20, 2024 OFFICE NRR/DRO/IRSB NMSS/DFM/MSB NMSS/DFM/FFLB*

NMSS/DFM/FFLB NAME TGovan TBoyce SLav JDowns for MBartlett DATE Sep 23, 2024 Sep 20, 2024 Oct 8, 2024 Oct 8, 2024