ML25339A124
| ML25339A124 | |
| Person / Time | |
|---|---|
| Site: | 05000614, 99902117 |
| Issue date: | 12/05/2025 |
| From: | Yazzie S Long Mott Energy |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML25339A122 | List: |
| References | |
| 2025-PLM-NRC-014 | |
| Download: ML25339A124 (0) | |
Text
1 Date: December 5, 2025 Docket No. 50-0614 LME Response to NRC RAI No. ACC-5 NRC RAI Letter No. ML25307A005 Dated November 6, 2025.
Regulatory Basis:
Long Mott Energy submitted an Environmental Report (ER), ML25090A063, as part of its CP application in accordance with 10CFR Part51, Environmental Protection Regulations for Domestic Licensing and Related Regulatory Functions. The Nuclear Regulatory Commissions (NRC) regulations at 10 CFR Part 51, which implement Section 102(2) of the National Environmental Policy Act (NEPA) of 1969, include requirements for applicants to provide information as may be useful in aiding the NRC sta in complying with NEPA, and other federal consultation obligations such as Section 106 of the NHPA and Section 7 of the Endangered Species Act and the Clean Air Act (CAA).
REQUIREMENT: 10 CFR 51.45(c) requires that the ER includes a description of the aected environment, contains sucient data to aid the Commission in its development of an independent analysis, and an analysis that considers and balances the environmental eects of the proposed action. Per NRC Regulatory Guide 4.2, this should include:
- An evaluation of the radiological consequences to the environment from potential accidents at the proposed site. The description of the design-basis accidents considered should include site-speci"c data and realistic meteorology (i.e., 50th percentile atmospheric dispersion) based on accident release assumptions described in the PSAR/FSAR.
RAI No: ACC-5 Please provide an updated Table 5.13.1-12 that is consistent with PSAR Table 3.2-5 providing both the safety dose, air dispersion conversion factor, and environmental dose. Please indicate if the calculated environmental dose is on a per module or total module basis for each DBA sequence.
2 LME Response:
Updated environmental DBA doses (attached) are calculated by applying a reduction factor to PSAR Table 3.2-5. Please note that PSAR Table 3.2-5 is the subject of Safety Evaluation audit questions and subject to change. The expected changes impact the DBEs mapped and are not expected to impact the DBAs or the DBA dose values. Because these PSAR audit issues are not "nalized, those edits are not included in the table.
Responder: Stephanie Yazzie Reviewer: Milton Gorden and Mark Feltner
DBE DBE Description DBA DBA Description modules(a)
Reduction Factor(c)
Best Estimate EAB Dose (rem) (d)
MCRW-01 modules 1-4 shut down, and then forced cooling for modules 1-4 is maintained by main feedwater pumps via steam generator main steam header and condenser until the plant reaches a safe stable state MCRW-07 modules 1-4 shut down, forced cooling after the initiating event is not maintained by main feedwater pumps via steam generator main steam header and condenser for module 1-4, and then successful SSS cooling in modules 1-4 is established and maintained until the plant reaches a safe stable state SCRW-07 module 1 shuts down, main steam header isolates in module 1, unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, modules 2-4 trip, and then forced cooling for modules 1-4 is maintained by main feedwater pumps via steam generator main steam header and condenser until the plant reaches a safe stable state SCRW-13 module 1 shuts down, main steam header isolates in module 1, unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, modules 2-4 trip, forced cooling after the initiating event is not maintained by main feedwater pumps via steam generator main steam header and condenser for modules 1-4, and then successful SSS cooling in modules 1-4 is established and maintained until the plant reaches a safe stable state MPLPF-08 Unsuccessful plant power runback, modules 1 & 2 shut down, main steam header isolates in modules 1 & 2, unsuccessful plant rebalance requires modules 3 & 4 to trip with main feedwater pump running, modules 3 & 4 trip, and then forced cooling for modules 1-4 is maintained by main feedwater pumps via steam generator main steam header and condenser until the plant reaches a safe stable state MPLPF-14 Unsuccessful plant power runback, modules 1 & 2 shut down, main steam header isolates in modules 1 & 2, unsuccessful plant rebalance requires modules 3 & 4 to trip with main feedwater pump running, modules 3 & 4 trip, forced cooling after the initiating event is not maintained by main feedwater pumps via steam generator main steam header and condenser for modules 1-4, and then successful SSS cooling in modules 1-4 is established and maintained until the plant reaches a safe stable state MTLPF-07 modules 1 & 2 shut down, main steam header isolates in modules 1 & 2, modules 3 & 4 do not trip after successful plant rebalance with main feedwater pump running, unsuccessful circulator restoration in modules 1 & 2, and then active RCCS cooling in modules 1 & 2 is maintained until the plant reaches a safe stable state MTLPF-22 modules 1 & 2 shut down, main steam header isolates in modules 1 & 2, unsuccessful plant rebalance requires modules 3 & 4 to trip with main feedwater pump running, unsuccessful circulator restoration in modules 1 & 2, and then active RCCS cooling in modules 1 & 2 is maintained until the plant reaches a safe stable state 9.74E-02 1
1.65E-01 5.29E-01 8.74E-02 SCRW-DBA Control Rod Withdrawal PSAR Section 3.6.1 Control rod withdrawal initiating event; reactivity controlled by inherent reactivity feedback; heat removal provided by passive RCCS cooling 4
1.84E-01 5.29E-01 MTLPF-DBA Loss of Primary Flow PSAR Section 3.6.2 Loss of primary flow initiating event; reactivity controlled by inherent reactivity feedback; heat removal provided by passive RCCS cooling 4
1.87E-01 5.29E-01 9.90E-02 3
SPLPF-14 Unsuccessful plant power runback, module 1 shuts down, main steam header isolates in module 1, unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, modules 2-4 trip, forced cooling after the initiating event is not maintained by main feedwater pumps via steam generator main steam header and condenser for modules 1-4, and then successful SSS cooling in modules 1-4 is established and maintained until the plant reaches a safe stable state SPLPF-19 Unsuccessful plant power runback, module 1 shuts down,main steam header isolates in module 1, unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, modules 2-4 fail to trip, and then active RCCS cooling in modules 1-4 is maintained until the plant reaches a safe stable state STLPF-22 module 1 shuts down, main steam header isolates in module 1, unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, unsuccessful circulator restoration in module 1, and then active RCCS cooling in module 1 is maintained until the plant reaches a safe stable state SD-74(e)
Unsuccessful HPB break isolation in module 1, module 1 shuts down, main steam header isolates in module 1, modules 2-4 do not trip after successful plant rebalance with main feedwater pump running, forced cooling for module 1 is not maintained by main feedwater pumps with the main steam header bypassed by a flow path through SSS to the condenser, unsuccessful SSS cooling in module 1, primary system pumpdown not credited in module 1, unsuccessful active RCCS cooling in module 1, and then passive RCCS cooling is maintained in module 1 until the plant reaches a safe stable state SD-76 Unsuccessful HPB break isolation in module 1, module 1 shuts down, main steam header isolates in module 1, unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, and then forced cooling for modules 1-4 is maintained by main feedwater pumps via steam generator main steam header and condenser until the plant reaches a safe stable state SD-84 Unsuccessful HPB break isolation in module 1, module 1 shuts down, main steam header isolates in module 1, unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, forced cooling after the initiating event is not maintained by main feedwater pumps via steam generator main steam header and condenser for modules 1-4, and then successful SSS cooling in modules 1-4 is established and maintained until the plant reaches a safe stable state SD-98 Unsuccessful HPB break isolation in module 1, module 1 fails to shut down, module 1 trips, main steam header isolates in module 1, modules 2-4 do not trip after successful plant rebalance with main feedwater pump running, and then forced cooling for module 1 is maintained by main feedwater pumps with the main steam header bypassed by a flow path through SSS to the condenser until the plant reaches a safe stable state.
1.28E+00 SD-DBA PSAR Section 3.6.3 Small depressurization initiating event; reactivity controlled by inherent reactivity feedback; heat removal provided by passive RCCS cooling 1
2.41E+00 5.29E-01 4
MD-63 Unsuccessful HPB break isolation in module 1, module 1-4 dampers open, module 1 trips, main steam header isolates in module 1, modules 2-4 do not trip after successful plant rebalance with main feedwater pump running, and then forced cooling for module 1 is maintained by main feedwater pumps with the main steam header bypassed by a flow path through SSS to the condenser until the plant reaches a safe stable state.
MD-68 Unsuccessful HPB break isolation in module 1, modules 1-4 dampers open, module 1 trips, main steam header isolates in module 1, Unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, and then forced cooling for modules 1-4 is maintained by main feedwater pumps via steam generator main steam header and condenser until the plant reaches a safe stable state MD-73 Unsuccessful HPB break isolation in module 1, module 1-4 dampers open, module 1 trips, Main steam header isolates in module 1, unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, forced cooling after the initiating event is not maintained by main feedwater pumps via steam generator main steam header and condenser for modules 1-4, and then successful SSS cooling in modules 1-4 is established and maintained until the plant reaches a safe stable state MTLFW-02 modules 1-4 shut down, unsuccessful SSS cooling in module 1-4, and then active RCCS cooling in modules 1-4 is maintained until the plant reaches a safe stable state MTLFW-DBA Loss of SG Feedwater PSAR Section 3.6.5 Loss of feedwater initiating event; reactivity controlled by inherent reactivity feedback; heat removal provided by passive RCCS cooling 4
1.59E-01 5.29E-01 8.42E-02 MFLB-01 modules 1-4 shut down, and then successful SSS cooling in modules 1-4 is established and maintained until the plant reaches a safe stable state SFLDBNI-01 module 1 shuts down, SG isolation valves close for module 1, modules 2-4 do not trip after successful plant rebalance with main feedwater pump running, circulators trip in module 1, and then forced cooling for module 1 is maintained by main feedwater pumps with the main steam header bypassed by a flow path through SSS to the condenser until the plant reaches a safe stable state.
SFLDBNI-16 module 1 shuts down, SG isolation valves close for module 1, unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, and then forced cooling for modules 1-4 is maintained by main feedwater pumps via steam generator main steam header and condenser until the plant reaches a safe stable state SFLMBRB-01 modules 1-4 shuts down, SG isolation valves close for module 1, modules 1-4 dampers open, forced cooling for modules 2-4 is maintained by main feedwater pumps via steam generator main steam header and condenser, and then active RCCS cooling in module 1 is maintained until the plant reaches a safe stable state 8.42E-02 MD-DBA PSAR Section 3.6.4 Medium depressurization initiating event; reactivity controlled by inherent reactivity feedback; heat removal provided by passive RCCS cooling 1
3.68E+00 5.29E-01 1.95E+00 MFLB-DBA PSAR Section 3.6.6 Main feedwater line break initiating event; reactivity controlled by inherent reactivity feedback; heat removal provided by passive RCCS cooling 4
1.59E-01 5.29E-01 5
SFLUBNI-01 module 1 trips, SG isolation valves close for module 1, modules 2-4 do not trip after successful plant rebalance with main feedwater pump running, and then forced cooling for module 1 is maintained by main feedwater pumps with the main steam header bypassed by a flow path through SSS to the condenser until the plant reaches a safe stable state.
MSLB-08(e) modules 1-4 shut down, forced cooling for modules 1-4 is not maintained by main feedwater pumps with the main steam header bypassed by a flow path through SSS to the condenser, unsuccessful SSS cooling in module 1-4, and then active RCCS cooling in modules 1-4 is maintained until the plant reaches a safe stable state SSLBNI-01 module 1 shuts down, SG isolation valves close for module 1, modules 2-4 do not trip after successful plant rebalance with main feedwater pump running, circulators trip in module 1, and then forced cooling for module 1 is maintained by main feedwater pumps with the main steam header bypassed by a flow path through SSS to the condenser until the plant reaches a safe stable state.
SSLBNI-16 module 1 shuts down, SG isolation valves close for module 1, unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, and then forced cooling for modules 1-4 is maintained by main feedwater pumps via steam generator main steam header and condenser until the plant reaches a safe stable state SSLBNI-22 module 1 shuts down, SG isolation valves close for module 1, Unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, forced cooling after the initiating event is not maintained by main feedwater pumps via steam generator main steam header and condenser for module 1-4, and then successful SSS cooling in module 1-4 is established and maintained until the plant reaches a safe stable state SSLSBRB-01 module 1 shuts down, SG isolation valves close for module 1, modules 2-4 do not trip after successful plant rebalance with main feedwater pump running, Circulators trip in module 1, and then forced cooling for module 1 is maintained by main feedwater pumps with the main steam header bypassed by a flow path through SSS to the condenser until the plant reaches a safe stable state.
SSGTL-07 module 1 shuts down, SG isolation valves close for module 1, SG dump path opens for module 1, SG dump path isolates for module 1, Unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, and then forced cooling for module 1-4 is maintained by main feedwater pumps via steam generator main steam header and condenser until the plant reaches a safe stable state SSGTL-13 module 1 shuts down, SG isolation valves close for module 1, SG dump path opens for module 1, SG dump path isolates for module 1, unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, forced cooling after the initiating event is not maintained by main feedwater pumps via steam generator main steam header and condenser for modules 1-4, and then successful SSS cooling in modules 1-4 is established and maintained until the plant reaches a safe stable state 1.20E-01 MSLB-DBA PSAR Section 3.6.7 Main steam line break initiating event; reactivity controlled by inherent reactivity feedback; heat removal provided by passive RCCS cooling 4
1.59E-01 5.29E-01 8.42E-02 SGTL-DBA PSAR Section Steam generator tube leak initiating event caused by 10 mm leak; steam generator is isolated by closure of the isolation valve to control water and steam 1
2.27E-01 5.29E-01 6
SSGTL-14 module 1 shuts down, SG isolation valves close for module 1, SG dump path opens for module 1, SG dump path isolates for module 1, unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, forced cooling after the initiating event is not maintained by main feedwater pumps via steam generator main steam header and condenser for module 1-4, unsuccessful SSS cooling in module 1-4, and then active RCCS cooling in modules 1-4 is maintained until the plant reaches a safe stable state SSGTL-18 module 1 shuts down, SG isolation valves close for module 1, SG dump path opens for module 1, SG dump path fails to isolate for module 1, and then active RCCS cooling in module 1 is maintained until the plant reaches a safe stable state SSGTR-01 module 1 shuts down, SG isolation valves close for module 1, SG dump path opens for module 1, SG dump path isolates for module 1, modules 2-4 do not trip after successful plant rebalance with main feedwater pump running, and then forced cooling for module 1 is maintained by main feedwater pumps with the main steam header bypassed by a flow path through SSS to the condenser until the plant reaches a safe stable state.
SSGTR-03 module 1 shuts down, SG isolation valves close for module 1, SG dump path opens for module 1, SG dump path isolates for module 1, modules 2-4 do not trip after successful plant rebalance with main feedwater pump running, forced cooling for module 1 is not maintained by main feedwater pumps with the main steam header bypassed by a flow path through SSS to the condenser, unsuccessful SSS cooling in module 1, and then active RCCS cooling in module 1 is maintained until the plant reaches a safe stable state SSGTR-07 module 1 shuts down, SG isolation valves close for module 1, SG dump path opens for module 1, SG dump path isolates for module 1, Unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, and then forced cooling for modules 1-4 is maintained by main feedwater pumps via steam generator main steam header and condenser until the plant reaches a safe stable state SSGTR-13 module 1 shuts down, SG isolation valves close for module 1, SG dump path opens for module 1, SG dump path isolates for module 1, Unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, forced cooling after the initiating event is not maintained by main feedwater pumps via steam generator main steam header and condenser for modules 1-4, and then successful SSS cooling in modules 1-4 is established and maintained until the plant reaches a safe stable state SSGTR-14 module 1 shuts down, SG isolation valves close for module 1, SG dump path opens for module 1, SG dump path isolates for module 1, unsuccessful plant rebalance requires modules 2-4 to trip with main feedwater pump running, forced cooling after the initiating event is not maintained by main feedwater pumps via steam generator main steam header and condenser for modules 1-4, unsuccessful SSS cooling in modules 1-4, and then active RCCS cooling in modules 1-4 is maintained until the plant reaches a safe stable 3.6.8 ingress; reactivity controlled by inherent reactivity feedback; heat removal provided by passive RCCS cooling SGTR-DBA PSAR Section 3.6.9 Steam generator tube rupture initiating event caused by 25 mm leak; steam generator is isolated by closure of the isolation valve to control water and steam ingress; reactivity controlled by inherent reactivity feedback; heat removal provided by passive RCCS cooling 1
2.27E-01 5.29E-01 1.20E-01 7
N/A The seismic analysis is deterministic, not derived from the PRA Seismic B-DBA PSAR Section 3.6.12 A seismic event creates a large (95) mm break at the point where the fuel handling inlet pipe connects to the top of the RPV on all four modules.
Reactor trips fail, all modules shut down on inherent reactivity feedback, main loop forced cooling fails, SSS fails, successful RCCS passive cooling in all four modules.
4 1.44E+01 5.29E-01 7.62E+00 Source: PSAR Table 3.2-5 Notes a) Indicates the number of modules experiencing the same type of event. For all DBAs, it is assumed that all four modules trip and contribute to the total offsite dose. However, this does not necessarily mean that all four modules experience the subject event.
b) Calculated at 3.57E-04 s/m3, PSAR Section 2.3.4.3 c) Reduction Factor = (1.89E-04 s/m3)/(3.57E-04 s/m3) d) Best Estimate reflects 1.89E-04 s/m3 e) This scenario is a BDBE. See Section 3.6 introduction for explanation.
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