ML24348A059
| ML24348A059 | |
| Person / Time | |
|---|---|
| Site: | 05200050 |
| Issue date: | 12/13/2024 |
| From: | NuScale |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML24348A006 | List:
|
| References | |
| LO-176318 | |
| Download: ML24348A059 (1) | |
Text
Response to NuScale Topical Report Audit Question Question Number: A-NonLOCA.LTR-40 Receipt Date: 05/28/2024 Question:
(( 2(a),(c) Please provide proposed markups to the TR to include the requested information.
Response
This is a revised response to audit question A-NonLOCA.LTR-40 to address NRC feedback received on July 12, 2024; the original response posted to the electronic reading room (eRR) on June 10, 2024 is unchanged in the eRR. The revised portion of the response begins with the section identified as Response to Additional NRC Feedback. The TR-0516-49416-P, Non-Loss-of-Coolant Accident Analysis Methodology, Revision 4, Section 4.3.5 identifies that VIPRE-01 is used for the subchannel analysis of non-loss-of-coolant accident (non-LOCA) events. The acceptance criteria of minimum critical heat flux ratio (MCHFR) and maximum fuel centerline temperature are therefore evaluated with VIPRE-01. Section 4.3.5 of TR-0516-49416-P describes that NRELAP5 is used to provide input to VIPRE-01. ((
}}2(a),(c)
NuScale Nonproprietary NuScale Nonproprietary
(( }}2(a),(c) NuScale Nonproprietary NuScale Nonproprietary
(( }}2(a),(c) NuScale Nonproprietary NuScale Nonproprietary
(( }}2(a),(c) Response to Additional NRC Feedback On July 12, 2024, the NRC provided the following feedback: (( }}2(a),(c) In response to the NRC feedback, Section 4.3.5 of TR-0516-49416-P, Revision 4, is revised as shown in the attached markups ((
}}2(a),(c)
Markups of the affected changes, as described in the response, are provided below: NuScale Nonproprietary NuScale Nonproprietary
Non-Loss-of-Coolant Accident Analysis Methodology TR-0516-49416-NP Draft Revision 5 © Copyright 2024 by NuScale Power, LLC 44 limiting initialization for a given transient progression to ensure the maximum power and core inlet fluid temperature are reached prior to reactor trip system actuation. For example, in the case of a heatup event, the RCS increases in temperature, causing a pressurizer insurge and subsequent increase in pressure. The limiting CHF scenario is the transient progression that results in the highest core outlet temperature at the time of reactor trip on high pressure, which is generally the faster heatups where the pressurizer initialization is biased to delay the high pressure trip. Audit Question A-NonLOCA.LTR-40 For some transients, a spectrum of cases is analyzed from the limiting initialization. (( Audit Question A-NonLOCA.LTR-23 }}2(a),(c) After the system transient analysis calculations are performed and assessed, for events that require subchannel analysis, a number of cases are identified as limiting for MCHFR. For the limiting cases selected, the required system transient parameters are tabulated as a function of time for input to the downstream subchannel analysis calculations, to calculate margin to CHF. The system transient parameters are provided for subchannel analysis for sufficient time for the subchannel analyses to demonstrate that the MCHFR has occurred, typically 10-15 seconds following reactor trip.}}