ML23159A096
| ML23159A096 | |
| Person / Time | |
|---|---|
| Site: | 99902071 |
| Issue date: | 07/19/2023 |
| From: | Michael Orenak NRC/NRR/DANU/UAL1 |
| To: | Proffitt J NRC/NRR/DANU/UAL1 |
| References | |
| EPID L-2022-TOP-0051 | |
| Download: ML23159A096 (4) | |
Text
MEMORANDUM TO:
Joseph A. Proffitt, Acting Chief Advanced Reactor Licensing Branch 1 Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation FROM:
Michael D. Orenak, Project Manager Advanced Reactor Licensing Branch 1 Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation
SUBJECT:
SUMMARY
OF THE APRIL 24, 2023, OBSERVATION MEETING BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION STAFF AND X ENERGY, LLC REGARDING THE ATMOSPHERIC DISPERSION AND DOSE CALCULATION METHODOLOGY TOPICAL REPORT Meeting Information:
Applicant: X Energy LLC Docket/Project No. 99902071 EPID: L-2022-TOP-0051 Meeting
Title:
Pre-submittal Discussion of X-energy Topical Report, Atmospheric Dispersion and Dose Consequences Methods Meeting Date: April 27, 2023 Meeting Type: Observation Public Meeting Notice Agencywide Documents Access and Management System (ADAMS):
ML23108A164 Public Meeting Slides: ML23107A143 Meeting Attendees: See Enclosure for list of meeting attendees.
CONTACT: Michael D. Orenak, NRR/DANU (301) 415-3229 July 19, 2023 Signed by Orenak, Michael on 07/19/23
J. Proffitt 2
Meeting Summary:
The U.S. Nuclear Regulatory Commission (NRC) staff held a virtual partially closed meeting with representatives from X-Energy, LLC (X-energy). The meeting was conducted in accordance with NRC Management Directive 3.5, Attendance at NRC Staff-Sponsored Meetings (ML21180A271).
During the public meeting, X-energy presented their slides detailing the approaches being taken for atmospheric dispersion and dose approach for the Xe-100 reactor.
The NRC asked that given the Xe-100 is planned to be built with four units on site, has there been any consideration for a multi-unit event and any impacts on cross-units control rooms.
X-energy responded that the current analysis is to look at the limiting unit. X-energy stated they will evaluate multi-units in the future, but that is out of the scope for this topical report.
The NRC staff noted that the proposed TR dispersion methodology describes use of a generic method to make calculations without local meteorological conditions, but for a license application, site-specific atmospheric dispersion analysis must be made. X-energy responded that the methodology is intended to be bounding to result in a set of enveloping atmospheric dispersion factors (/Qs, pronounced chi over Qs). The NRC staff also noted that the topical report should describe the technical basis for the use of reduction factors, as taken from referenced documents, including application of the Ramsdell-Fosmire correlation.
The NRC staff also confirmed that X-energy intended to use equations from NRC Regulatory Guide (RG) 1.194, Atmospheric Relative Concentrations for Control Room Radiological Habitability Assessments at Nuclear Power Plants (ML031530505), and RG 1.145, Atmospheric Dispersion Models for Potential Accident Consequence Assessments at Nuclear Power Plants (ML003740205), with conservative generic values to develop the dispersion analysis. Then, once the specific site is known, X-energy will perform an ARCON analysis with site-specific meteorological information. The two analyses would be compared, and the most conservative atmospheric dispersion factors will be used as input to the dose analysis to support the license application (i.e., construction permit application).
The NRC staff noted that X-energy referenced NRC Draft Guide (DG) 4030. Because DG-4030 has yet to be approved, any topical report or application must have a full description of the methodology until the resulting Regulatory Guide is issued.
The NRC staff noted that for all /Q equations in the topical report, a value for each variable should be provided to support the NRC staffs review.
The NRC staff noted that the topical report should describe all reduction factors, how and why they are used (e.g., evaluation of design basis accident (DBA) consequences vs. use in the NEI 18-04, Revision 1, Risk-Informed Performance-Based Guidance for Non-Light Water Reactor Licensing Basis Development (ML19241A336), approach (non-DBAs)), and why they are appropriate to use in the methodology.
The NRC staff asked whether a point source is being used instead of a diffuse source for control room dose. X-energy clarified that it was a diffuse source consistent with guidance in RG 1.194.
J. Proffitt 3
The NRC staff noted the topical report methodology for non-DBAs would result in a best-estimate dose offsite. The NRC staff asked how the methodology would estimate consequence uncertainty as needed for the NEI 18-04 approach. X-energy indicated that uncertainty analysis is still under consideration.
The NRC staff asked for clarification if the control room /Qs were best-estimate or 95th percentile (conservative) considering the slide indicating that the event for control room dose was for non-DBAs only. X-energy responded that the control room /Qs will be conservative and will not use a reduction factor. X-energy clarified that the evaluated events for the control room dose analysis would be non-DBAs, consistent with the discussion in the X-energy topical report on principal design criteria (PDC), specifically that PDC-19 for the control room does not consider it to be required for defense-in-depth. The NRC staff stated that there was no precedent for not including evaluation of DBAs in the control room habitability evaluation, and the NRC staff would have to take additional time to consider this approach. X-energy stated the discussion of source terms and radiological releases are out of scope for this topical report and noted that it is a topic for future discussion.
There were no public comments at the end of the meeting. X-energy stated they would provide the topical report by the end of the following week (May 5th).
J. Proffitt 4
SUBJECT:
SUMMARY
OF THE APRIL 27, 2023, OBSERVATION MEETING BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION STAFF AND X ENERGY, LLC REGARDING THE ATMOSPHERIC DISPERSION AND DOSE CALCULATION METHODOLOGY TOPICAL REPORT DATED: JULY 19, 2023 DISTRIBUTION:
Public RidsOgcMailCenter RidsOpaMail Resource RidsNrrDanu Resource RidsNrrDanuUarl Resource JProffitt, NRR MOrenak, NRR SDevlinGill, NRR MHart, NRR JWhite, NRR JSchaperow, NRR ADAMS Accession Number: ML23159A096 NRR-052 OFFICIAL RECORD COPY OFFICE NRR/DANU/UAL1/PM NRR/DANU/UAL1/BC (A)
NRR/DANU/UAL1/PM NAME MOrenak JProffitt MOrenak DATE 7/05/2023 7/19/2023 7/19/2023
Enclosure List of Attendees Partially Closed Meeting Between the U.S. Nuclear Regulatory Commission Staff and X Energy, LLC Regarding the Graphite Material Qualification Methodology White Paper Monday, April 24, 2023 Name Organization Mike Orenak U.S. Nuclear Regulatory Commission (NRC)
Andrew Proffitt NRC Stephanie Devlin-Gill NRC Michelle Hart NRC Jason Schaperow NRC Jason White NRC Ingrid Nordby X-Energy LLC (X-energy)
Travis Chapman X-energy Jon Facemire X-energy Brian Froese X-energy Daniel Strohmeyer X-energy Jessica Maddocks X-energy Julia Sharma X-energy Stephanie Yazzie X-energy Yvonne Mirowski X-energy Wesley Steh X-energy Milton Gordon X-energy Martin van Staden X-energy Carl Friesen US Department of Energy Dominik Muszyn Lisa Momkus Oklo Lisa Matis Jodine Vehec Jana Bergman Curtiss Wright Matt Denman Kairos