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ACRS CPA Presentation - Oct 23 Open (Fh Sodium Fire IC Structures)
	ML25293A257
Person / Time
Site:	Kemmerer File:TerraPower icon.png
Issue date:	10/23/2025
From:	; TerraPower
To:	; Office of Nuclear Reactor Regulation
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SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved a TerraPower & GE Vernova Hitachi Nuclear Energy technology Kemmerer Unit 1 ACRS Subcommittee Meeting Natrium Design ACRS Subcommittee Meeting October 23, 2025

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved a TerraPower & GE Vernova Hitachi Nuclear Energy technology Fuel Handling Systems Overview

FHI includes the equipment necessary to manipulate the positions of core assemblies during Mode 4 refueling operations and maintain the functional containment boundary when the equipment is installed

Primary components consist of IVTM, which is used to transfer core assemblies in RV, and FTL, which is used to transfer core assemblies out of RV to FHE

FHI can move core assemblies within the core, from core location to the In-Vessel Storage location outside the core, and from any location within the core to the FTL.

FHE includes equipment that facilitates receipt, inspection, conditioning, storage, installation, and removal of all core assemblies

During refueling outages, the EVHM moves non-irradiated and irradiated core assemblies between the RV located in the RXB and the EVST located in the FHB.

Following refueling outage, the BLTC moves irradiated core assemblies from EVST to PIC to be processed for storage in SFP

The BLTC is utilized to transfer core assemblies from the NAPS to the EVST in preparation for a refueling outage

FHP provides water-based environment for intermediate-term storage of spent fuel and is used for storage of non-fuel irradiated core assemblies prior to disposal Provides core assembly cooling, spent fuel reactivity control, fission product containment, and radiation shielding PIC transitions core assemblies being stored in sodium environment to water-filled environment FHP is divided into 4 subsystems:

SFP

PIC

Fuel Pool Cooling (FPC)

Fuel Pool Purification (FPP)

Fuel Handling Overview

Function ID Function Description Safety Classification DL3-RR1f The FHI seals to the reactor head perform part of the primary coolant boundary barrier (primary functional containment boundary) function.

SR FHI provides a temporary load path function (NSRST) and a structural support load path function (SR) for core assemblies being transferred, charged or discharged in RV, that do not require continuous load path structural support

Function ID Function Description Safety Classification DL3-HR6 Passive Heat Removal in EVHM SR DL3-HR7 Passive Heat Removal in EVST SR DL3-HR8 Passive Heat Removal in BLTC SR DL3-HR9 Passive Heat Removal in PRC SR DL3-RR3 EVHM Cask Barrier SR DL3-RR3a EVHM Transfer Barrier Function SR DL3-RR4 EVST Barrier SR

Function ID Function Description Safety Classification DL3-RR5 BLTC Barrier SR DL3-RR5a BLTC Transfer Barrier SR DL3-RR6 PRC Cell Barrier SR DL4-RR5 EVST Guard Tank Leak Prevention NSRST DL5-PAM1 Post Accident Monitoring NSRST EVST provides SR structural support load path function for SR components EVHM, BLTC, PRC, and CAP provide temporary load path function (NSRST) for SR SSCs during fuel movement activities

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved FHP - System Safety Functions 10 Function ID Function Description Safety Classification DL3-HR10 Passive Heat Removal in FHP SR DL3-HR13 Passive Heat Removal in the FFC SR DL3-RR8 Failed Fuel Canister Barrier SR DL3-RR5a BLTC Transfer Barrier SR DL4-HR4 FHP Emergency Makeup NSRST DL2-RR2 PIC Radionuclide Boundary NSRST DL5-PAM1 Post Accident Monitoring NSRST Intact and failed fuel racks provides SR structural support load path function for SR components PHM and PIC provide temporary load path function (NSRST) for SR SSCs during fuel movement activities

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved 11 Fuel Handling - R&D System Component CTE PSAR TRL Relevance to Safety Case In-Vessel Fuel Handling System In-Vessel Transfer Machine Grapple Finger Operation 3

The grapple finger manipulates core assemblies from within the RV during refueling operations and is part of a SR load path IVTM Grapple Finger operation is assigned TRL 3 based on need for additional R&D testing in representative sodium environment and will test integrated performance and reliability of grapple fingers Grapple finger operation will be tested to confirm operability including full scale air and sodium prototype testing

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved a TerraPower & GE Vernova Hitachi Nuclear Energy technology Sodium Fire and Leak Mitigation Overview

Detects, collects, and contains sodium leaks to mitigate the effects of sodium fires

Leak prevention is addressed by sodium system design

SSCs consist of sodium leak detectors, wiring, guard enclosures, steel plating, splash guards, drain lines, heat tracing, and catch pans

As guard pipes provide full secondary pressure-boundary for sodium containing piping, they are part of system design and not NNA

Detection and monitoring capabilities provide defense in depth and provide operators with early notification of leaks so they can take necessary action

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved NNA - System Safety Functions 15 Function ID Function Description Safety Classification DL4-RR3a SPS Supply Valve Isolation on Leak Detection NNA sends leak detection signal to AMC. AMC automatically closes SPS-P valve.

NSRST DL4-RR3b SPS Pumps Trip on Leak Detection NNA sends leak detection signal to AMC. AMC automatically trips SPS-P pumps.

NSRST DL4-RR3c SPS Cells Barrier Isolation on Leak Detection NNA sends leak detection signal to the UMC. UMC automatically closes NHV dampers.

NSRST DL4-DID1 NNA shall provide additional protection for prevention of adverse conditions in the HAA to establish reasonable confidence risk remains within targets NSRST

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved Inerted Cell Vessel or Component Process Pipe Process Drain Tank Process Drain Line Mechanical Joint Catch Pan Guard Enclosure 5

4 3

Drain Lines Non-inerted Cell Steel plating Catch Pan 1

Steel plating Catch Pan 2

NNA Concepts for Sodium Containing SSCs Steel plating 6

Leak prevention is applied through sodium system design

Includes selection of materials appropriate for sodium environment

ASME codes are applied based on the safety classification of the SSC and temperature of the system

Special treatments are applied to provide increased assurance SSC design basis functions can be achieved

Sodium fire protection strategy is based on a defense-in-depth fire protection design approach and utilizes leak prevention, detection and passive mitigation

Leak detection is provided by leak detectors in all areas containing sodium

Passive leak mitigation is provided through various means depending on the system and the function the leak mitigation feature is intended to protect

Primary SPS piping includes a guard pipe that retains leaks within the guard pipe (through RXB penetrations)

IHT SSCs in HAA include guard enclosure or clamshell that contains leaks and drain to catch pans in RAB pipe chase (through RXB penetrations)

Catch pans are sized to accommodate 125% of the design basis leak from sodium source it is collecting from

Leaks are postulated for all piping that normally contain sodium and criteria are adapted from NUREG-0800, BTP 3-3 and BTP 3-4, for moderate energy piping

Considers additional criteria for high-temperature creep from ASME BPVC Section III Division 5

Sodium pipe ruptures are postulated for piping areas subject to high stress

Postulated design basis ruptures are deterministically bound by Dt/4 crack for seismically qualified piping and full-circumferential break for non-seismically qualified piping

Leakage cracks in smaller pipes are considered when determining worst-case leaks in each area (i.e., BTP 3-4 provision to eliminate 1-inch or smaller pipes from analysis is not used)

Consideration for Dt/4 or full circumferential breaks may be excluded from sodium piping for:

For low stress piping regions per applicable stress limits from BTP-3-4, safety classification, pipe class, and temperature

Piping regions with negligible creep per Appendix HCB-III, ASME BPVC Section III, Division 5

Methodology for long-term creep for high temperature piping will be provided at operating license stage

Design basis leakage cracks will be postulated for areas excluded from Dt/4 or full circumferential breaks at operating license stage

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved a TerraPower & GE Vernova Hitachi Nuclear Energy technology I&C Systems Overview

RPS accepts input signals from plant instrumentation, applies required logic, and automatically generates output to initiate SR reactor trip and ESF actuations and NSRST CRD scram driveline follow signals

XIS provides instrumentation to sense neutron flux during fuel movement, reactor startup, power operations, reactor shutdown, and LBEs and provides inputs to RPS and NIC

RIS provides instrumentation to monitor selected parameters in or near RV and provides inputs to the RPS and NIC

NIC is group of systems that perform NSRST and NST control and monitoring functions

Collection of sub-systems and is implemented on distributed control system

RMS provides both NSRST and NST radiation monitoring indications during operation, refueling, and post-accident conditions

AST senses ground motion and provides signal to open RPS trip breakers in response to seismic BDBE

NSRST signal is separate from RPS coincidence logic

PAM NSRST and NST functionality is provided using NIC and RPS NSRST I&C - System Overview

Safety Classification DL3-RC1a Reactor scram on high-high neutron flux (RPS, XIS)

SR DL3-RC1b Reactor scram on high-high hot pool temperature (RPS, RIS)

SR DL3-RC1c Reactor scram on high-high primary sodium level (RPS,RIS)

SR DL3-RC1d Reactor scram on high-high power-to-flow ratio (RPS, XIS, RIS)

SR DL3-RC1e Reactor scram on high-high cold pool temperature (RPS, RIS)

SR DL3-RC1f Reactor scram on high-high positive neutron rate (RPS, XIS)

SR DL3-RC1g Reactor scram on high-high negative neutron rate (RPS, XIS)

SR DL3-RC1h Reactor scram on low-low primary sodium level (RPS, RIS)

SR DL3-RC1i Reactor scram on low power, high neutron flux (RPS, XIS)

SR DL3-RC1j Reactor scram on primary low of sodium flow (RPS, RIS)

SR DL3-RC2 Reactor scram on loss of power (RPS)

SR

Safety Classification DL3-HR2 PSP trip on high-high primary sodium temperature (RPS, XIS, RIS)

SR DL3-HR3 ISP trip on high-high primary sodium temperature (RPS, XIS, RIS)

SR DL3-HR11 SPS pump trip on low primary sodium level (RPS, RIS)

SR DL3-HR12 ISP trip on high-high primary sodium level (RPS, XIS, RIS)

SR DL4-RC1 Reactor scram-manual (RPS)

NSRST DL4-RC3 CRD driveline scram follow (RPS)

NSRST DL4-RC4 Automatic seismic trip (RPS, AST)

NSRST DL4-HR6 Manual PSP trip (RPS)

NSRST DL4-HR7 Manual ISP trip (RPS)

NSRST DL4-RR8 Manual SPS pump trip on low primary sodium level (RPS, RIS)

NSRST DL5-PAM1 Post-accident monitoring (RPS, XIS, RIS, RMS)

NSRST

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved I&C - NIC Safety Functions 28 Function ID Function Description Safety Classification DL4-RR3a SPS supply valve isolation on leak detection (AMC)

NSRST DL4-RR3b SPS pump trip on leak detection (AMC)

NSRST DL4-RR4a Automatically close SCG isolation valves on leak detection (RMC, AMC)

NSRST DL2-HR2 ISP trip on low IHT level (CTC)

NSRST DL4-HR2 PSP trip on automatic backup (RIS, CTC)

NSRST DL4-HR3 ISP pump trip automatic backup (RIS, CTC)

NSRST DL4-RR1c HAA HVAC operations following postulated release (RMS, UMC)

NSRST DL4-RR3c SPS cells barrier isolation leak detection (UMC)

NSRST DL4-RR4b SCG cells barrier isolation leak detection (RMS, UMC)

NSRST DL4-RR4c Vapor trap cell isolation (UMC)

NSRST

4 RPS divisions leverage internal diversity of Curtiss-Wright RadICS platform

I&C systems have simple design

DID features are identified using NEI 18-04 process

Cyber-security requirements are considered throughout design process I&C Summary

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved a TerraPower & GE Vernova Hitachi Nuclear Energy technology Safety-Significant Structures Overview

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved SUBJECT TO DOE COOPERATIVE AGREEMENT NO.DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved General Plant Layout 32

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved NI Buildings Safety Functions 33 Function ID Function Description Safety Classification DL3-HR4 Inherent RAC Operation The portions of the RXB substructure maintains the outer boundary of the RAC air flow path.

SR DL4-RR1 Ex-RES Functional Containment Barrier Functional containment barrier that encompasses the primary system boundary, including the RES barrier NSRST DL4-RR1a HAA Barrier Sub-function of the ex-RES functional containment barrier (DL4-RR1) that includes the HAA barrier NSRST DL4-RR7 Fuel Handling Building Barrier FHB superstructure is designed for a slightly negative pressure as part of enveloping barrier NSRST DL4-RR3 SPS Cells Barrier The RAB substructure provides an enveloping barrier for radionuclide retention in the SPS cells NSRST

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved SUBJECT TO DOE COOPERATIVE AGREEMENT NO.DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved NI Buildings Functional Containment Barriers 34

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved NI Buildings Safety Functions 35 Functional Requirement Function Description Safety Classification Specific SR Load Paths The RSS transfers loads from the RES to the RXB substructure.

The RAC stacks are supported by the RXB substructure. Portions of RXB also provide flow path for RAC operation.

SR Specific NSRST Load Paths The RXB substructure walls & slabs provide load paths for NSRST SSCs performing PSFs inside the substructure NSRST Temporary Load Paths for SR SSCs At-grade slabs of RXB substructure, FHB substructure and transfer corridor between RXB & FHB supports the PSF of temporary load path for FHEs performing their PSFs NSRST External Hazard Protection Protect SR & NSRST SSCs by designing NI structures to applicable codes and standards to withstand DBHLs without loss of structural integrity SR & NSRST

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved Safety & Seismic Classifications Primary Design & Analysis Codes NI Buildings Seismic Design 36 Building SR SCS1 NSRST SCN1 NST RXB Substructure X

RXB Superstructure X*

FHB Substructure X

FHB Superstructure X

RAB Substructure X

RAB Superstructure X

NCB Substructure X

NCB Superstructure X

Code Applicability Safety Classification SR NSRST ACI 301-05 Structural Concrete Specification X

ACI 301-16 Structural Concrete Specification X

ACI 318-08 Concrete Structure - Limit State Design Method (in conjunction with ACI349-13 and ACI 301-05)

X ACI 318-19 Concrete Structure - Limit State Design Method (in conjunction with ACI301-16)

X ACI 349-13 Concrete Structure - Limit State Design Method X

AISC 341-16 Structural Steel Seismic Design Provisions X

X AISC 348-14 Specification for Structural Joints Using High-Strength Bolts X

X AISC 360-16 Structural Steel - Load and Resistance Factor Design (in conjunction with AISC348-14)

X AISC N690-18 Structural Steel - Load and Resistance Factor Design ( in conjunction with AISC360-16)

X ASCE/SEI 4-16 Dynamic Analysis Considerations X

ASCE/SEI 7-16 General Design Basis Loads and Seismic Design Methodology X

X ASCE 43-19 Seismic Design Criteria X

IBC 2021 Building Design Code for State of Wyoming X

Design equivalent to SCN1 as a seismic interaction source in seismic interactive prevention design

SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright © 2025 TerraPower, LLC. All Rights Reserved ACI - American Concrete Institute AISC - American Institute of Steel Construction AMC - Auxiliary Monitoring and Control System ASCE - American Society of Civil Engineers ASME - American Society of Mechanical Engineers AST - Anticipatory Automatic Seismic Trip System BDBE - Beyond Design Basis Event BLTC - Bottom Loading Transfer Cask BPVC - Boiler and Pressure Vessel Code BTP - Branch Technical Position CAP - Core Assembly Pot CFR - Code of Federal Regulations CRD - Control Rod Drive System CTC - Coolant Temperature Monitoring and Control System CTE - Critical Technology Element DBHL - Design Basis Hazard Level DID - Defense In Depth ESF - Engineered Safety Feature EVHM - Ex-Vessel Handling Machine EVST - Ex-Vessel Storage Tank FHB - Fuel Handling Building FHE - Ex-Vessel Fuel Handling System FHI - In-Vessel Fuel Handling System FHP - Water Pool Fuel Handling System FPC - Fuel Pool Cooling FPP - Fuel Pool Purification FTL - Fuel Transfer Lift HAA - Head Access Area I&C - Instrumentation and Control IBC - International Building Code IEEE - Institute of Electrical and Electronics Engineers IHT - Intermediate Heat Transport System ISP - Intermediate Sodium Pump IVS - In-Vessel Storage IVTM - In-Vessel Transfer Machine LBE - Licensing Basis Event MCR - Main Control Room NCB - Nuclear Island Control Building NEI - Nuclear Energy Institute NHV - Nuclear Island Heating, Ventilation, and Air Conditioning System NI - Nuclear Island NIC - Nuclear Island Control System NNA - Sodium Leak Detection, Collection, and Containment System NSS - Nuclear Island Salt System NST - Non-Safety-Related with No Special Treatment NSRST - Non-Safety-Related with Special Treatment NSS - Nuclear Island Salt System PAM - Post Accident Monitoring PDC - Principal Design Criteria PHM - Pool Handling Machine PIC - Pool Immersion Cell PRA - Probabilistic Risk Assessment PSAR - Preliminary Safety Analysis Report PSF - PRA Safety Function PSP - Primary Sodium Pump R&D - Research and Development RAB - Reactor Auxiliary Building RAC - Reactor Air Cooling System RES - Reactor Enclosure System RIS - Reactor Instrumentation System RMC - Rod Monitoring and Control System RMS - Radiation Monitoring System RPS - Reactor Protection System RSC - Remote Shutdown Complex RV - Reactor Vessel RXB - Reactor Building SCG - Sodium Cover Gas System SFP - Spent Fuel Pool SPS - Sodium Processing System SR - Safety-Related SSC - Structures, Systems, and Components TRL - Technology Readiness Level UMC - Utility Monitoring and Control System XIS - Nuclear Instrumentation System Acronyms 38

ML25293A257

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