ML18192C078
| ML18192C078 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 07/11/2018 |
| From: | Office of New Reactors |
| To: | |
| References | |
| LAR 18-009 | |
| Download: ML18192C078 (1) | |
Text
10 CFR Part 50, Appendix A, General Design Criterion (GDC) 34, "Residual heat removal", requires the plant design to provide a system to remove residual heat. The safety system function shall be to transfer fission product decay heat and other residual heat from the reactor core at a rate such that specified acceptable fuel design limits and the design conditions of the reactor coolant pressure boundary are not exceeded.
License Amendment Request (LAR)18-009 states "In MODE 5, vacuum fill configuration, the PRHR HX is not credited in the safety analysis to remove decay heat. If decay heat removal by the RNS is lost during vacuum fill, the heat removal function is provided by the vent path through the ADS valves and the injection flow path from the IRWST with containment closure capability provided."
NRC staff is seeking clarification regarding the referenced safety analysis in order to establish a finding that the supporting safety analysis is acceptable.
Specifically, NRC staff documented their examination of APP-SSAR-GEF-088, Revision 0, "Small Break LOCA (SBLOCA), Loss of Normal Residual Heat Removal System (RNS)
Cooling, and Long Term Core Cooling Mass and Energy Release Assessment of Outstanding Design Debt," Attachment D, "Shutdown Loss-of-RNS Debt Assessment Evaluation," in an audit summary associated with LAR 17-027, "Reactor Coolant System Vacuum Fill and ITAAC for Containment Floodup" (ML18074A142) and needs to confirm whether this same analysis is supporting LAR 18-009. Accordingly, NRC staff requests that the licensee (1) confirm that Attachment D of APP-SSAR-GEF-088 is the safety analysis that is referenced in LAR 18-009, and (2) provide a brief summary of the supporting safety analysis describing the evaluation model, input parameters and initial conditions (including which equipment is operable and credited for event mitigation),
and the analysis conclusions.