ML24348A069
| ML24348A069 | |
| Person / Time | |
|---|---|
| Site: | 05200050 |
| Issue date: | 12/13/2024 |
| From: | NuScale |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML24348A006 | List:
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| References | |
| LO-176318 | |
| Download: ML24348A069 (1) | |
Text
Response to NuScale Topical Report Audit Question Question Number: A-NonLOCA.LTR-45 Receipt Date: 06/17/2024 Question:
The current revision of the non-LOCA LTR contains provisions to provide bounding mass release values to the radiological analysis rather than mass release values based on transient results. However, the topical report only provides an example for an unspecified transient but does not provide a method to select bounding values for particular transients. Therefore, NRC staff approval will be of use of bounding values in lieu of values derived from transient analysis, but the method by which applicants and licensees select bounding values and the justification that said values are bounding is not reviewed and approved with this topical report and will be subject to application-specific NRC staff review. If more extensive approval is desired, provide LTR markups that specify the method by which bounding values are selected for specific transients with either justification that this method results in bounding values, or description of checks that will be performed (e.g., comparison with transient results as suggested in the LTR example) to provide assurance that values are bounding.
Response
In Revision 4 of TR-0516-49416-P, Non-Loss-of-Coolant Accident Analysis Methodology, NuScale revised Section 4.3.6 to allow for use of bounding values for radiological analysis as an alternative to providing event-specific transient results into the downstream radiological analysis. Section 4.3.6 identified an example method to determine bounding values. There are other methods that could be used to determine bounding values, depending on the level of conservatism desired. The specific bounding values, and the justification of those values, is provided on an application-specific basis. In the case of the Standard Design Approval Application (SDAA) for the US460 design, the bounding values and associated justification are provided in Chapter 15 of the Final Safety Analysis Report (FSAR).
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Given that Section 4.3.6 of TR-0516-49416-P only describes an example, NuScale has no objection to the approach identified by the NRC in the audit question. Therefore, NuScale proposes no changes to TR-0516-49416-P in response to this audit question.
Note that the change to TR-0516-49416-P was to add the option to use bounding values as an alternative to the previously approved event-specific transient methodology (i.e., not to replace it). Therefore, the NRC approval of the use of bounding values should not negate the validity of the previously approved event-specific transient methodology.
No changes to the SDAA are necessary.
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