ML24128A255
| ML24128A255 | |
| Person / Time | |
|---|---|
| Site: | 99902094 |
| Issue date: | 04/05/2024 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML24128A253 | List: |
| References | |
| Download: ML24128A255 (1) | |
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Public Meeting with the University of Illinois at Urbana-Champaign Regarding Principal Design Criteria Topical Report April 5, 2024
Introductions
2
Agenda
- Discuss draft NRC requests for additional information (RAIs) on the UIUC Topical Report, University of Illinois Urbana-Champaign High Temperature Gas-cooled Research Reactor: Micro Modular Reactor (MMRTM)
Principal Design Criteria, submitted November 15, 2023 (ADAMS Accession No. ML23319A407)
- Discuss other NRC staff questions on the UIUC Topical Report
- Open discussion
- Questions
- Public Comments 3
Draft RAI 1 PDC 15: The NRC staff notes that the language proposed in the TR University of Illinois Urbana-Champaign High Temperature Gas-cooled Research Reactor: Micro Modular Reactor (MMRTM) Principal Design Criteria, Release 1 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23319A407), for principal design criterion (PDC) 15 reflects that of NRC Regulatory Guide (RG) 1.232, Developing Principal Design Criteria for Non-Light Water Reactors, Revision 0 (ML17325A611), Appendix C, Modular High-Temperature Gas-Cooled Reactor Design Criteria, criterion 15 (i.e., MHTGR-DC 15),
but with the phrase All systems that are part of the helium pressure boundary, such as removed. The comment provided in TR Appendix A, "Comparison of RG 1.232 Appendix C MHTGR-DC and USNC MMR PDC, mentions a conflict between NRC and USNC terminology related to the helium pressure boundary (HPB). Provide further explanation regarding this conflict in terminology and how the difference necessitates the proposed language change. Additionally, indicate whether there are any MMR structures, systems, or components to which PDC 15 would apply if the wording in RG 1.232 were unchanged, but to which it would not apply because of the proposed change. If there are, provide an explanation for the exclusion and the bases used to determine that this conforms with applicable regulatory requirements.
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Draft RAI 2 PDC 16: The NRC staff notes that the language proposed in the TR for PDC 16 deviates from the language used in RG 1.232, Appendix C, criterion 16 (i.e., MHTGR-DC 16). The reason for the proposed changes is unclear to the NRC staff. Specifically, MHTGR-DC 16 verbiage is generally understood to encompass the functional containment capacity of advanced reactor fuel forms, such as TRISO and/or FCM. Additionally, the proposed verbiage appears to change the intent of the criterion from requiring a functional containment to requiring an analysis of a functional containment. Finally, the staff notes that identifying specific design features to be relied upon to meet functional containment requirements is not generally necessary and may limit future design flexibility. Explain and/or revise, as appropriate, the proposed PDC 16 language.
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Draft RAI 3 PDC 32: The NRC staff notes that the wording as applicable or justification if not required added to proposed PDC 32 compared to RG 1.232, Appendix C, criterion 32 (i.e.,
MHTGR-DC 32) is not completely clear. Specifically, the proposed additional language does not clearly imply whether it is applicable to the whole criterion (i.e., both (1) and (2)) or just to (2). Additionally, the phrase or justification if not required does not grammatically align with the structure of the remainder of the language. As appropriate, revise PDC 32 to articulate its intent more clearly.
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Draft RAI 4 Although TR Section 1.4 states that UIUC requests an NRC safety evaluation of the USNC MMRTM PDCs provided in Section 4 and listed in Appendix A to be used for the UIUC MMRTM, the NRC staff notes that some statements in the TR (e.g., in Section 5.0) appear to imply that the PDCs in the TR would be applicable to any future reactor applications under Parts 50 or 52 using the USNC MMR design, not just the UIUC research reactor. The NRC staff notes that the TR was submitted by UIUC under the project no. 99902094 which was created to support activities pertaining to UIUCs pre-application engagement with the NRC for the research reactor planned to be sited at the UIUC campus. The NRC staff understands this TR was submitted for review as part of pre-application activities that directly support the anticipated future applications for a construction permit and operating license for a research reactor to be sited at the UIUC campus. Please confirm that the applicability of the TR is limited to future applications from UIUC to construct and operate a research reactor at UIUC using the USNC MMR design, and clarify the TR as appropriate.
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Additional Discussion Item 1 PDC 19: To reflect UIUC MMR design intentions, specifically that operator actions not be required in response to accidents, the term monitor is used instead of maintain with respect to accident response design features. To ensure that the exclusion of design features intended to provide for operator actions in response to accident conditions is justified, a TR limitation or condition (L/C) or PDC language update may be necessary, as follows:
- a. L/C (example/draft wording only; approval of any PDC(s) and/or any final L/C language is subject to the completion of the NRC staffs review): UIUC MMR PDC 19 reflects the passive nature of the UIUC MMR design, which is intended to ensure adequate cooling during accident conditions without any reliance on operator actions. As such, the PDC language does not specify design features to support operator actions to maintain the unit in a safe condition under accident conditions. The NRC staff finds UIUC MMR PDC 19 acceptable under the condition that licensing actions referencing this PDC shall provide adequate justification (potentially by reference to another NRC-approved licensing action that provides justification) to support the underlying assumption that operator action is not required to maintain the nuclear power unit in a safe condition under accident conditions, as appropriate to the context and detail of the referencing licensing action.
- b. OR UIUC could edit the proposed PDC 19 language itself, to specify that the design shall ensure that operator action is not required to maintain the nuclear power unit in a safe condition under accident conditions, and therefore only monitoring is to be provided for.
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Additional Discussion Item 2 PDC 37: TR Section 4.4.6 provides PDC-37 with the inclusion of as applicable when referencing the functional testing of structural and leak tight integrity of components with respect to the passive residual heat removal system.
Comments provided note this deviation but not an explanation as to the purpose. This alteration implies that some portions of the system will have a design so as not to permit or plan for functional testing of structural or leak tight integrity as per a screening criterion determining what is applicable. Please elaborate on the inclusion of this language and its intention.
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- Open discussion
- Questions
- Public Comments 10