ML25028A267

X-Energy, LLC - NRC Audit Plan for XE-100 Graphite Core Assembly Material Qualification and Design Methodologies Topical Report

ML25028A267
Person / Time
Site:	99902071
Issue date:	01/28/2025
From:	Adrian Muniz NRC/NRR/DANU/UAL2
To:	X-Energy
References
EPID L-2024-TOP-0032, CAC 000431
Download: ML25028A267 (1)

Text

X-ENERGY LLC - AUDIT PLAN FOR XE-100 TOPICAL REPORT GRAPHITE CORE ASSEMBLY MATERIAL QUALIFICATION AND DESIGN METHODOLOGIES, REVISION 1 (CAC / EPID NO. 000431 / L-2024-TOP-0032)

APPLICANT INFORMATION Applicant:

X Energy, LLC Applicant Address:

530 Gaither Road, Suite 700, Rockville, MD, 20850 Design Name:

Xe-100 Project No(s):

99902071

Background:

By letter dated November 1, 2024, X Energy, LLC (X-energy) submitted topical report (TR) 009380, Xe-100 Licensing Topical Report Graphite Core Assembly Material Qualification and Design Methodologies, Revision 1 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24306A125). This TR describes (1) the material qualification methodology and associated test plan for the graphite core assembly (GCA), (2) the design methodology for the GCA and associated components, (3) use of the Irradiated Graphite Numerical Iterative Solver (IGNIS) within the design methodology, and (4) the application of NEI 18-04, Risk-Informed Performance-Based Technology Inclusive Guidance for Non-Light Water Reactor Licensing Basis Development, (ML19241A472) to the GCA.

This audit is in support of the U.S. Nuclear Regulatory Commission (NRC) staffs safety review of the TR submitted by X-energy.

Purpose:

The purpose of the audit is for the NRC staff to gain a more detailed understanding of X-energys GCA material qualification and design methodologies, and to identify any information that will require docketing to support the NRC staffs safety evaluation of the subject TR which is expected to be referenced in future licensing applications for X-energys Xe-100 reactor design.

Therefore, the NRC staff is requesting access to X-energy documents associated with the GCA material qualification and design methodologies as referenced in the TR.

Regulatory Audit Basis:

This regulatory audit focuses on the information contained in TR 009380, Xe-100 Licensing Topical Report Graphite Core Assembly Material Qualification and Design Methodologies, Revision 1. The regulatory requirements applicable to this topical report are as follows:

Title 10 of the Code of Federal Regulations (10 CFR) 50.34(a)(4) requires an applicant for a construction permit (CP) to perform a preliminary analysis and evaluation of the design and performance of structures, systems, and components (SSCs) with the objective of assessing the

2 risk to public health and safety resulting from operation of the facility and including determination of margin of safety during normal operations and transient conditions. These analyses are generally associated with the principal design criteria (PDC) and associated SSC design bases. X-energy submitted TR Xe-100 Principal Design Criteria, Revision 3 (ML24047A308) which was reviewed and approved by the NRC staff in the safety evaluation (ML24284A012). Section 2.1, Regulatory Requirements, of the TR identifies the following PDC as applicable to the Graphite Core Assembly (GCA):

PDC-Required Functional Design Criterion (RFDC) 26: The reactor core shall be designed to include movable poisons that can insert and maintain safe shutdown during design basis events (DBEs) and design basis accidents (DBAs)

PDC-RFDC 34: A passive system shall be designed to ensure that acceptable fuel and radionuclide release limits are not exceeded during DBEs and DBAs PDC-RFDC 70: The reactor core shall be designed such that the reactor vessel and reactor system geometry is maintained to (1) ensure geometry for passive removal of residual heat from the reactor core to the ultimate heat sink and (2) permit sufficient insertion of neutron absorbers to provide for reactor shutdown.

10 CFR 50.34(b)(4) requires an applicant for an operating license to perform a final analysis and evaluation of the design and performance of SSCs with the objective stated in 10 CFR 50.34(a)(4).

10 CFR 50.35(a)(3) enables issuance of a CP if a research and development program can be reasonably designed to resolve any safety questions associated with safety features or components. Such research and development may include obtaining sufficient data on the safety features of the design to assess the analytical tools used for safety analysis in accordance with 10 CFR 50.43(e)(iii).

10 CFR 50.43(e)(1)(iii) requires (for applications for an operating license, design certification, combined license, standard design approval, or manufacturing license which differ significantly from light-water reactor designs that were licensed before 1997) that sufficient data exist on the safety features of the design to assess the analytical tools used for safety analyses over a sufficient range of normal operating conditions, transient conditions, and specified accident sequences, including equilibrium core conditions.

Regulatory Audit Scope:

The audit will follow the guidance in NRR Office Instruction LIC-111 (ML19226A274),

Regulatory Audits, and focus on information provided by X-energy through the electronic reading room, and, if necessary, onsite visits.

3 Information and Other Material Necessary for the Regulatory Audit:

The NRC staff requests that the following references from the TR be made available upon audit entrance:

GCA Graphite Material Qualification Plan (Document No. 009186)

Xe-100 Design Methodology for Graphite Core Assembly and Graphite Core Components (Document No. 009650)

Graphite Material Model Overview: IGNIS (Document No. 009815)

Xe-100 NEI 18-04 Implementation methodology for the Graphite Core Assembly (GCA)

(Document No. 009322)

Additional material may be requested as needed.

Team Assignments:

Meg Audrain Materials Engineer, Audit Technical Lead Joseph Bass Reactor Engineer Alex Chereskin Materials Engineer Tim Drzewiecki Senior Reactor Systems Engineer Matthew Gordon Materials Engineer Ian Jung Senior Reliability and Risk Analyst Clair Song Mechanical Engineer Vince Voltaggio Reactor Engineer Adrian Muniz Senior Project Manager Ondra Dukes Project Manager Members of the audit team may change during the audit.

Logistics:

Entrance Meeting February 3, 2025 Exit Meeting Week of May 26, 2025 (estimate)

Audit meetings will take place in a virtual format, using Microsoft Teams or another similar platform. Audit meetings will be scheduled as needed after the entrance meeting. The audit will begin on February 3, 2025, and continue as necessary, with activities occurring intermittently during the audit period. The audit period may be reduced or extended, depending on the progress made by the NRC staff and X-energy in addressing audit questions.

Special Requests:

The NRC staff requests that X-energy subject matter experts are available to answer questions during the audit. The NRC staff also requests that X-energy provides access to supporting documents via the X-energy electronic reading room. X-energy should track the NRC staffs audit questions and make the responses available in the electronic reading room.

In addition, if there is any information (e.g., revised markups to the TR) identified during the audit that will require docketing to support the NRC staffs safety evaluation, the NRC staff requests that X-energy make the draft information available in the electronic reading room for discussion with the NRC staff before the information is formally docketed.

4 Deliverables:

At the completion of the audit, the NRC staff will issue an audit summary within 90 days after the exit meeting. The audit summary will be made publicly available in ADAMS.

References:

Title 10 of the Code of Federal Regulations.

If you have questions about this audit, please contact me at 301-415-4093 or via email at adrian.muniz@nrc.gov or Ondra Dukes at 301-415-0537 or via email at ondra.dukes@nrc.gov.

Date: January 28, 2025 Adrian Muniz, Senior Project Manager /RA/

Advanced Reactors Licensing Branch 2 Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation Docket No.: 99902071 cc: X-energy Xe-100 via GovDelivery

ML25028A267 NRR-106 OFFICE NRR/DANU/UAL2:PM NRR/DANU/UAL2:PM NRR/DANU/UTB3:BC NAME ODukes AMuniz GOberson DATE 01/26/2025 01/27/2025 01/27/2025 OFFICE NRR/DANU/UAL2:BC NRR/DANU/UAL2:BC(A)

NAME JSegala AMuniz DATE 01/27/2025 01/28/2025