ML24348A054
| ML24348A054 | |
| 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: ML24348A054 (1) | |
Text
Response to NuScale Topical Report Audit Question Question Number: A-NonLOCA.LTR-37 Receipt Date: 05/06/2024 Question:
Provide a methodology that must be used to determine the time-in-cycle core average burnup is used to calculate the fuel thermal conductivity as a function of temperature or incorporate the approach in the revision 3 of this TR with updated burnup values with which the fuel thermal conductivities are calculated.
TR Section 4.3.1.2.2, Fuel Rod Material Properties, states: the fuel pellet properties, UO2 properties are used to reflect the core average response. Since the fuel pellet thermal conductivity is a function of burnup and fuel temperature, and the fuel pellet thermal conductivity degrades with burnup, a representative time-in-cycle core average burnup is used to calculate the fuel thermal conductivity as a function of temperature. However, the TR does not provide a methodology for determining this value. The staff asked the same question during its review of Revision 3 of this TR (ML19039A090). (( 2(a),(c),ECI Please provide proposed markups to the TR.
Response
Section 2.2.3 of EC-0000-7782, Revision 3, NPM-20 NRELAP5 Basemodel (previously provided in the electronic reading room (eRR)) describes the treatment of fuel exposure in the NRELAP5 basemodel for the NuScale Power Module (NPM) for the US460 Standard Design Approval Application (i.e., the NPM-20). (( }}2(a),(c),ECI NuScale Nonproprietary NuScale Nonproprietary
(( }}2)a,(c),ECI the burnup limit of approximately 60 GWd/MT described in Final Safety Analysis Report Chapter 4. The treatment of fuel exposure in the NPM-20 basemodel in EC-0000-7782 is then expanded in the non-loss-of-coolant accident (non-LOCA) basemodel in EC-0000-8507, Revision 2, NPM-20 NRELAP5 Non-LOCA Model (provided in the eRR with this response). (( }}2)a,(c),ECI The tables of biases in Section 7.2 of TR-0516-49416-P, Revision 4, Non-Loss-of-Coolant Accident Methodology, identify fuel temperature is biased low, nominal, or high, depending on the event. (( }}2)a,(c),ECI The methodology in Section 4.3.1.2.2 of TR-0516-49416-P, Revision 4, specifies that a representative time-in-cycle core average burnup be used. ((
}}2)a,(c),ECI As identified by the reference in this audit question, the previous version of TR-0516-49416-P that was reviewed and approved by the NRC (i.e., Revision 3) did not provide a more detailed discussion of the burnup or a specific burnup value in the topical report itself. Instead, the information was provided by NuScale in support of an NRC audit. Consistent with the approach taken during the review and approval of TR-0516-49416-P-A, Revision 3, NuScale has provided NuScale Nonproprietary NuScale Nonproprietary
the more detailed information in this audit response and is not including the information in the topical report itself. Therefore, no markups are required. No changes to the SDAA are necessary. NuScale Nonproprietary NuScale Nonproprietary}}