ML23354A009
| ML23354A009 | |
| Person / Time | |
|---|---|
| Site: | 99902094 |
| Issue date: | 12/19/2023 |
| From: | Edward Helvenston NRC/NRR/DANU |
| To: | Brooks C University of Illinois |
| References | |
| L-2022-NFN-0011 | |
| Download: ML23354A009 (4) | |
Text
From:
Edward Helvenston Sent:
Tuesday, December 19, 2023 5:41 PM To:
Brooks, Caleb Cc:
Grunloh, Timothy P; lfoyto@illinois.edu; Kelly Sullivan; Patrick Boyle; Paulette Torres; Greg Oberson (He/Him); Holly Cruz (She/Her/Hers); Dan Beacon (He/Him)
Subject:
Request for Additional Information Regarding UIUC Event Sequence Identification and SSC Safety Classification Methodology Attachments:
UIUC Safety Classification and Event Sequence Identification Methodology TR RAIs (final).pdf
Dear Dr. Brooks:
By letter dated September 7, 2023 (Agencywide Documents Access and Management System (ADAMS)
Package Accession No. ML23250A318), University of Illinois at Urbana-Champaign (UIUC) submitted Revision 0 of the topical report (TR), University of Illinois Urbana-Champaign High Temperature Gas-cooled Research Reactor: Event Sequence Identification and SSC Safety Classification Methodology, for the U.S. Nuclear Regulatory Commission (NRC) staffs review.
The U.S. Nuclear Regulatory Commission (NRC) staff identified additional information needed to continue its review of the TR, as described in the enclosed request for additional information (RAI). As discussed, provide a response to the RAI or a written request for additional time to respond, including the proposed response date and a brief explanation of the reason, by January 19, 2024. Following receipt of the complete response to the RAI, the NRC staff will continue its review of the topical report.
If you have any questions regarding the NRC staffs review or if you intend to request additional time to respond, please contact me at (301) 415-4067 or by electronic mail at Edward.Helvenston@nrc.gov.
Sincerely, Ed Helvenston, U.S. NRC Non-Power Production and Utilization Facility Licensing Branch (UNPL)
Division of Advanced Reactors and Non-Power Production and Utilization Facilities (DANU)
Office of Nuclear Reactor Regulation (NRR)
O-6B22 (301) 415-4067 Project No. 99902094 EPID: L-2022-NFN-0011
Enclosure:
As stated cc: GovDelivery Subscribers Concurrence on RAI Questions OFFICE NRR/DANU/UTB1/BC NRR/DANU/UNPL/BC(A) NRR/DANU/UNPL/PM NAME GOberson HCruz EHelvenston DATE 12/12/2023 12/12/2023 12/19/2023
Hearing Identifier:
NRR_DRMA Email Number:
2347 Mail Envelope Properties (BY5PR09MB59566205EC0087066D947614E097A)
Subject:
Request for Additional Information Regarding UIUC Event Sequence Identification and SSC Safety Classification Methodology Sent Date:
12/19/2023 5:41:06 PM Received Date:
12/19/2023 5:41:00 PM From:
Edward Helvenston Created By:
Edward.Helvenston@nrc.gov Recipients:
"Grunloh, Timothy P" <tgrunloh@illinois.edu>
Tracking Status: None "lfoyto@illinois.edu" <lfoyto@illinois.edu>
Tracking Status: None "Kelly Sullivan" <Kelly.Sullivan@nrc.gov>
Tracking Status: None "Patrick Boyle" <Patrick.Boyle@nrc.gov>
Tracking Status: None "Paulette Torres" <Paulette.Torres@nrc.gov>
Tracking Status: None "Greg Oberson (He/Him)" <Greg.Oberson@nrc.gov>
Tracking Status: None "Holly Cruz (She/Her/Hers)" <Holly.Cruz@nrc.gov>
Tracking Status: None "Dan Beacon (He/Him)" <Daniel.Beacon@nrc.gov>
Tracking Status: None "Brooks, Caleb" <csbrooks@illinois.edu>
Tracking Status: None Post Office:
BY5PR09MB5956.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 1812 12/19/2023 5:41:00 PM UIUC Safety Classification and Event Sequence Identification Methodology TR RAIs (final).pdf 91908 Options Priority:
Normal Return Notification:
No Reply Requested:
No Sensitivity:
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OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR ADDITIONAL INFORMATION EVENT SEQUENCE IDENTIFICATION AND SAFETY CLASSIFICATION METHODOLOGY TOPICAL REPORT UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN PROJECT NO. 99902094 Based on its review, the NRC staff requires the following additional information to continue its review of the University of Illinois at Urbana-Champaign (UIUC) topical report (TR).
- 1) The TR University of Illinois Urbana-Champaign High Temperature Gas-cooled Research Reactor: Event Sequence Identification and SSC Safety Classification Methodology, Revision 0 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23250A318), in Section 3.1, discusses how the proposed definition of safety-related (SR) UIUC has proposed for its reactor will meet the intent of the 10 CFR 50.2 definition of SR structures, systems, and components (SSCs). However, the staff notes that the proposed definition of SR in TR Section 3.2.2 specifies SSCs that are relied upon during and following all event sequences and that event sequences are defined in TR Sections 2.2.2 and 2.3.3 as conditions based on limiting postulated initiating events (PIEs), which based on the examples provided in TR Appendix A, all appear to be off-normal events. The 10 CFR 50.2 definition of SR SSCs includes, in part, SSCs that are relied upon during and following design basis events to assure 2) the capability to shut down the reactor and maintain it in a safe shutdown condition. The staff notes that, per 10 CFR 50.49 (which the staff notes is not applicable to research reactors, but which does apply to nuclear power plants that use the 10 CFR 50.2 definition of SR SSCs), design basis events are considered conditions of normal operation, including anticipated operational occurrences. As such, the staff considers the intent of the 10 CFR 50.2 definition of SR SSC to include SSCs required to achieve safe shutdown from normal operations.
Is UIUCs definition of SR in TR Section 3.2.2 intended to include SSCs required for safe shutdown from normal operations, as well as those that are relied upon during and following event sequences? If so, clarify the definition or explain how it meets this intent.
- 2) TR Section 3.3.1 states [t]he limiting PIEs will be identified and serve as an input in the safety classification methodology. However, the application of this statement in the context of the TR is not fully clear. Please clarify the statement in TR Section 3.3.1. Specifically:
- a. Describe what a "limiting PIE" is and how a PIE is determined to be limiting (i.e., what figure(s) of merit would be used).
- b. Describe how "limiting PIEs" align with the event sequence categories described in TR Section 2.3.4. Does each category have a single limiting PIE (e.g., as described in NUREG-1537, Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors (ML042430055 and ML04243055)) or multiple limiting PIEs, and how is that decided?
- c. When classifying SSCs based on limiting PIEs alone, how will consideration be given to PIEs that were not considered limiting, but rely on different SSCs than the limiting case?
For example, if SSC A is relied upon to mitigate PIE X, and SSC B is relied upon to mitigate PIE Y, how does the methodology classify SSC A, if PIE Y is identified as the "limiting PIE" of the two (particularly for potential cases when the failure of SSC A following PIE X could result in measurable consequences)?