ML24346A195
| ML24346A195 | |
| Person / Time | |
|---|---|
| Site: | 05200050 |
| Issue date: | 12/11/2024 |
| From: | NuScale |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML24346A130 | List:
|
| References | |
| LO-175762 | |
| Download: ML24346A195 (1) | |
Text
Response to NuScale Technical Report Audit Question Question Number: A-4.FuelCR.TeR-6 Receipt Date: 02/26/2024 Question:
For axial growth, provide the calculation that determines the maximum fast fluence. The staff notes that the new value is (( 2(a),(c),ECI whereas in the DCA it was (( }} 2(a),(c),ECI (Section 4.1.6 of TR-117605-P). Although the power has increased, the maximum burnup which is proportional to fluence has only been increased a small amount. Provide proposed markup to the TeR that provides the basis for the calculated fluence value.
Response
In TR-117065-P, Revision 1, NuFuel-HTP2'Fuel and Control Rod Assembly Designs, the (( }}2(a),(c),ECI allowable fast fluence value is a byproduct of mechanical calculations that predict when the gap between the fuel rod and the top nozzle closes. [ ] (( }}2(a),(c),ECI. The fast fluence analysis did not determine expected fluence predictions for the fuel, but this analysis determined the allowable fluence NuScale Nonproprietary NuScale Nonproprietary
value to protect the criterion that the fuel rod is not predicted to grow to the point of contact with the top nozzle. For the fuel axial growth analysis in TR-0816-51127, Revision 3, for the US600 design, a different approach was used. (( }}2(a),(c),ECI The difference between the US600 and US460 fluence values is that the US460 fluence represents the fluence where the fuel rod to top nozzle gap approaches zero and the US600 fluence is an expected end-of-life (EOL) fluence that results in a large EOL fuel rod to top nozzle gap. Response Supplement TR-117605-P, Revision 1, NuFuel-HTP2'Fuel and Control Rod Assembly Designs will not be updated to include how the fluence in Section 4.1.6 was calculated. The following is an excerpt from Section 4.2.4.1.1 of the Safety Evaluation Report for FSAR Chapter 4 from the Design Certification Application (ML20205L411) regarding axial growth with emphasis in bold: Section 4.1.6, Axial Growth, of TR-0816-51127, Revision 3, provides a growth analysis performed for the life of the fuel in accordance with EMF-92-116(P)(A), Revision 0. The staff finds that the analysis demonstrates, using the worst case tolerances and growth models, that sufficient clearance is maintained between the fuel assembly and top nozzle and between the fuel assembly and core plate. The fluence calculated for the US460 design is more conservative than the calculation performed for the US600, but is still performed in accordance with EMF-92-116(P)(A), Revision
- 0. The conclusions emphasized above are still applicable without adding explicitly how the fluence was calculated in the technical report.
No changes to the SDAA are necessary. NuScale Nonproprietary NuScale Nonproprietary}}