ML21053A201
| ML21053A201 | |
| Person / Time | |
|---|---|
| Issue date: | 03/02/2021 |
| From: | Benjamin Beasley NRC/NRR/DANU/UARL |
| To: | Irish S Terrestrial Energy USA LTD |
| Adrian Muniz, NRR/ DANU 301-415-4093 | |
| Shared Package | |
| ML21053A100 | List: |
| References | |
| EPID No. L-2020-LRO-0034 | |
| Download: ML21053A201 (3) | |
Text
OFFICIAL USE ONLY PROPIETARY INFORMATION Feedback for TEUSA PDC White Paper Note: (( )) denotes proprietary information.
By letter dated January 6, 2021 (Agencywide Documents Access and Management System Accession No. ML21025A031), Terrestrial Energy USA (TEUSA) submitted a revision to the white paper titled, Principal Design Criteria for IMSR Structures, Systems and Components in response to previous NRC comments. The staff reviewed the revisions made to the white paper and is providing the following feedback regarding the changes. The staff has grouped the feedback into three categories: (1) the staff is satisfied with the revisions and does not feel that additional changes to the white paper or feedback is necessary, (2) the staff does not necessarily feel that additional changes to the white paper are likely to be necessary, but did want to provide feedback based on the revisions to either confirm understanding or to provide feedback that should be considered in future licensing actions, and (3) the staff feels that additional revisions to the Principal Design Criteria (PDC) white paper are likely necessary.
Category 1: The staff reviewed the response provided by TEUSA for the following items, and does not have any additional feedback regarding the revisions to the white paper: 1, 4, 5, 6, 10, 11, 15, 17, 18, 19, 22, 23, 24, and 26 (Please note that the numbers refer to the Item Numbers in the original staff feedback and not PDC numbers).
Category 2: For the following items, the staff has some additional feedback for consideration but does not feel that additional revisions to the PDC white paper is necessary:
Item NRC Feedback or Discussion Number 2 The staff notes that the TEUSA response indicates that they intend to ((
)) This feedback is intended for future licensing actions and no further action is required for the PDC white paper.
3 It appears the paper still uses primary coolant and fuel salt interchangeable.
However, the NRC staff doesnt think it is crucial to revise the white paper.
7&8 The NRC staff reads ((
.)) The staff does not expect changes to the white paper to be necessary, but did want to clarify the intended application of the PDC before making that conclusion.
9 The staff is tentatively satisfied with the provided response, but additional design information might be necessary. The staff would like to learn if there are other sources of moderator materials (e.g. water) that would be available and could lead to a criticality event. The staff cannot imagine a situation where this would arise, but discussion of the design might be necessary before concluding that no additional changes are necessary.
Enclosure 2 OFFICIAL USE ONLY PROPIETARY INFORMATION
OFFICIAL USE ONLY- PROPIETARY INFORMATION 12 This may be better addressed in the future. However, salt retention of radionuclides is a unique feature of MSRs. The PDCs may need to reflect unique features of a design. Therefore, it is still not clear to the NRC staff whether [
]. A quick clarification discussion with TEUSA regarding this topic for normal operation and anticipated operational occurrences might prevent the need of additional modifications to the white paper.
16 The staff does not have specific information that is required to be added at this time; however, further discussion is needed to fully understand how the IMSR responds to various transients and what safety systems are relied upon. Depending on the outcome of that discussion, there might be additional information needed to be included in various PDCs.
20 The staff would be very interested in seeing the calculations that support this position during future reviews. ((
)). However, this would be in the postulated accident realm and therefore, no additional modifications are necessary for this white paper.
21 The feedback is addressed although there may still be some ambiguity in the use of cover gas vs off gas throughout the document. The staff would like to discuss to ensure common understanding of the definitions.
23 The staff wants to confirm that the definitions for off-gas and cover gas are the same between the PDC white paper and the Interfaces white paper. It appears the white papers describe these systems slightly differently which may contribute to confusion regarding the function for each system.
25 The response to the NRC staff feedback appears to indicate the IMSR design ((
.))
TEUSA should consider whether (( .))
Category 3: For the following items, the staff has additional feedback for consideration and believes that additional revisions to the PDCs might be necessary:
Item NRC Feedback or Discussion Number 13 &14 The NRC staff wishes to clarify the initial feedback provided for PDC 10. The feedback was not meant to ((
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OFFICIAL USE ONLY PROPIETARY INFORMATION
.)) Also, note that if other PDCs are impacted by this feedback, they should be analyzed as well.
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