ML25106A273

Transcript of Advisory Committee on Reactor Safeguards - Terrestrial Energy USA (Teusa) Subcommittee Meeting, March 20, 2025, Pages 1-81 (Open)

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Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION

Title:

Advisory Committee on Reactor Safeguards, Terrestrial Energy USA (TEUSA)

Open Session Location:

teleconference Date:

Thursday, March 20, 2025 Work Order No.:

NRC-0268 Pages 1-52 NEAL R. GROSS AND CO., INC.

Court Reporters and Transcribers 1716 14th Street, N.W.

Washington, D.C. 20009 (202) 234-4433

NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 1

1 2

3 DISCLAIMER 4

5 6

UNITED STATES NUCLEAR REGULATORY COMMISSIONS 7

ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 8

9 10 The contents of this transcript of the 11 proceeding of the United States Nuclear Regulatory 12 Commission Advisory Committee on Reactor Safeguards, 13 as reported herein, is a record of the discussions 14 recorded at the meeting.

15 16 This transcript has not been reviewed, 17 corrected, and edited, and it may contain 18 inaccuracies.

19 20 21 22 23

1 UNITED STATES OF AMERICA 1

NUCLEAR REGULATORY COMMISSION 2

+ + + + +

3 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 4

(ACRS) 5

+ + + + +

6 TERRESTRIAL ENERGY USA (TEUSA) SUBCOMMITTEE 7

+ + + + +

8 OPEN SESSION 9

+ + + + +

10 THURSDAY 11 MARCH 20, 2025 12

+ + + + +

13 The Subcommittee met via Video-14 Teleconference, at 8:30 a.m. EDT, Scott P. Palmtag, 15 Chair, presiding.

16 17 COMMITTEE MEMBERS:

18 SCOTT P. PALMTAG, Chair 19 RONALD G. BALLINGER, Member 20 VICKI M. BIER, Member 21 VESNA B. DIMITRIJEVIC, Member 22 CRAIG D. HARRINGTON, Member 23 GREGORY H. HALNON, Member 24 ROBERT P. MARTIN, Member 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

2 DAVID A. PETTI, Member 1

THOMAS E. ROBERTS, Member 2

MATTHEW W. SUNSERI, Member 3

4 ACRS CONSULTANTS:

5 DENNIS BLEY 6

STEPHEN SCHULTZ 7

8 DESIGNATED FEDERAL OFFICIAL:

9 CHRISTOPHER BROWN 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

3 TABLE OF CONTENTS 1

AGENDA PAGE 2

Opening Remark and Objectives..........

4 3

Staff Opening Remarks..............

7 4

Reactor Design Overview Summary......... 10 5

Principal Design Criteria Topical Report

.... 37 6

Public Comments................. 51 7

Transition to Closed Session

.......... 52 8

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

4 P R O C E E D I N G S 1

8:30 a.m.

2 CHAIR PALMTAG: Good morning. This 3

meeting will now come to order. This is a meeting of 4

the Terrestrial Energy Subcommittee on the Advisory 5

Committee on Reactor Safeguards. I am Scott Palmtag, 6

chair of today's subcommittee meeting. ACRS members 7

in attendance in person are Ron Ballinger, Matthew 8

Sunseri, Greg Halnon, Craig Harrington, Robert Martin, 9

Dave Petti, Tom Roberts, and myself. ACRS members in 10 attendance virtually are Vesna Dimitrijevic and Vicki 11 Bier. We have two consultants today virtually by 12 Teams, and that's Steve Schultz and Dennis Bley. If 13 I have missed anyone, either ACRS members or 14 consultants, please speak up now.

15 Christopher Brown of the ACRS staff is the 16 Designated Federal Officer for the meeting. No member 17 conflicts of interest were identified for today's 18 meetings. We have a quorum for today's meeting.

19 During today's meeting, the subcommittee 20 will receive a briefing on the topical report and 21 staff's draft safety evaluation for Terrestrial Energy 22 principal design criteria (PDCs) for the integral 23 molten salt reactor (IMSR) structure systems and 24 components, Revision C. The PDCs are integral to the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

5 review of the unique aspects of the design. In 1

addition, PDCs aid in the NRC staff's evaluation of 2

applicable regulations and allow the NRC staff to 3

assess with reasonable assurances that an advanced 4

reactor technology will conform to the proposed design 5

base with adequate margins of safety. We are 6

reviewing this topical report because it serves as a 7

foundation for the safety design approach for the 8

IMSR.

9 The ACRS was established by statute and is 10 governed by the Federal Advisory Committee Act, or 11 FACA. The NRC implements FACA in accordance with our 12 regulations.

Per these regulations and the 13 committee's bylaws, the ACRS speaks only through the 14 published letter reports. All member comments should 15 be regarded as only the individual opinion of that 16 member, not a committee position.

17 All relevant information related to ACRS 18 activities, such as letters, rules for meeting 19 participation, and transcripts are located on the NRC 20 public website and can easily be found by typing about 21 us ACRS in the search field on NRC's homepage.

22 The ACRS, consistent with the agency's 23 value on public transparency in regulation of nuclear 24 facilities provides opportunity for public input and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

6 comment during our proceedings. We have received no 1

written statements or requests to make an oral 2

statement from the public. However, we have also set 3

aside time at the end of this meeting for public 4

comments.

5 Portions of this meeting may be closed to 6

protect sensitive information, as required by FACA and 7

the Government in the Sunshine Act. Attendance during 8

the closed portion of the meeting will be limited to 9

the NRC staff and its consultants, applicants, or 10 licensees. And those individuals and organizations 11 will have entered into an appropriate confidentiality 12 agreement. We will confirm that only eligible 13 individuals are in the closed portion of this meeting 14 when it starts.

15 The ACRS will gather information, analyze 16 relevant issues and facts, and formulate proposed 17 conclusions and recommendations, as appropriate, for 18 deliberation by the full committee. A transcript of 19 this meeting is being kept and will be posted on our 20 website.

21 When addressing the subcommittee, the 22 participant should first identify themselves and speak 23 with sufficient clarity and volume so that they may be 24 readily heard. If you are not speaking, please mute 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

7 your computer on Teams or by pressing *6 if you're on 1

the phone.

2 Please do not use the Teams chat feature 3

to conduct sidebar discussions related to the 4

presentations. Rather, limit the meeting chat 5

function to report IT problems.

6 For everyone in the room, please keep all 7

your electronic devices in silent mode and mute your 8

laptop microphone and speakers. In addition, please 9

keep sidebar discussions in the room to a minimum 10 because the ceiling microphones are live.

11 For the presenters, your table microphones 12 are unidirectional and you'll need to speak into the 13 front of the microphone straight-on to be heard. You 14 also have to bring them fairly close to your mouth.

15 Finally, if you have any feedback for the 16 ACRS about today's meeting, we encourage you to fill 17 out the public meeting feedback form on the NRC's 18 website.

19 We will now proceed with the meeting, and 20 I'd like to call on John Segala, branch chief of NRR, 21 for opening remarks.

22 MR. SEGALA: Thank you, chair and 23 subcommittee. Good morning. I'm John Segala. I'm 24 chief of the Advanced Reactor Licensing Branch 2 in 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

8 the Division of Advanced Reactors in Non-Power 1

Production and Utilization Facilities in NRR.

2 Over the past six years, Terrestrial 3

Energy has been having pre-application engagement with 4

the NRC staff on their integral molten salt reactor 5

design. During that time, the NRC staff has reviewed 6

and provided written feedback on eight white papers 7

and one technical report. The NRC staff is also 8

currently reviewing a topical report on postulated 9

initiating events, as well as a technical report on 10 source term. Both of these reports have been preceded 11 by white papers where we have provided written 12 feedback on them.

13 As you mentioned, we're here today to have 14 Terrestrial and the NRC staff brief the ACRS 15 subcommittee on Terrestrial's principal design 16 criteria topical report and the NRC staff's safety 17 evaluation. To help provide context for this topical 18 report, Terrestrial is going to present a design 19 overview of their IMSR, and that should help add a 20 framework for the discussion today.

21 We understand that ACRS is maybe initially 22 thinking that they would not issue a letter on this 23 topical report. The NRC staff is not requesting one, 24 but we do look forward to having discussions today 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

9 with the subcommittee and hearing your input and your 1

feedback on this topical report. I believe that 2

completes my opening remarks.

3 Okay. Thank you. All right. We'll now 4

turn it over to Darren Love, who will give a reactor 5

design overview summary.

6 MR. AKSTULEWICZ: So, chairman, I'll be 7

introducing folks at the table first to help you. To 8

my far left is Simon Irish, the president of 9

Terrestrial Energy. To his right is Darren Love, who 10 is the director of engineering, and he will be doing 11 the presentation on the systems and structures for the 12 IMSR. My name is Frank Akstulewicz. I am the 13 licensing manager for regulatory efforts for 14 Terrestrial Energy here in the U.S., and to my right 15 is Bill Smith who is the senior vice president for 16 operations and engineering. Also in the audience is 17 the vice president for business development and 18 project management.

19 So I'd like to thank the committee for the 20 opportunity to come before you and present information 21 about the IMSR. This is our first opportunity to 22 present to you on this particular model. Simon would 23 like to have a few introductory remarks before we get 24 into the presentation, so if that's okay.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

10 MR. IRISH: Thank you, Frank. Chairman, 1

it's a pleasure to be here today. We, as a company, 2

have spent the last over a decade committed to 3

developing the IMSR system. We have, over the last 4

two years, recognized market demand is such that we 5

are accelerating that development. This meeting today 6

is an important milestone in our regulatory engagement 7

with the NRC and represents our first topical report.

8 We have come here today, I think, with a 9

full technical team and look forward to answering and 10 assisting in the answers of any questions that may be 11 discussed by the ACRS this morning. Thank you very 12 much.

13 MR. LOVE: Good morning, chairman and 14 fellow ACRS members. I'm grateful for the opportunity 15 to present the design overview of the IMSR. My name 16 is Darren Love. I am the engineering director for 17 Terrestrial Energy. The engineering department of 18 Terrestrial Energy is responsible for

design, 19 development, modeling, and simulation activities for 20 the IMSR nuclear power plant. I've been with 21 Terrestrial Energy for four years, serving first as a 22 mechanical engineering manager prior to becoming the 23 engineering director. Prior to joining Terrestrial 24 Energy, I worked within the oil and gas industry 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

11 performing fitness-for-service inspections and 1

engineering analysis services for many of the world's 2

leading refineries.

3 The integral molten salt reactor 4

technology builds upon the extensive research 5

conducted at Oakridge National Laboratories. The 6

concept of the molten salt reactor dates back to the 7

late 1940s with the Aircraft Reactor Experiment being 8

the first molten salt reactor to operate from 1953 to 9

1954. The ORNL further advanced the MSR developments 10 with the Molten Salt Reactor Experiment, which 11 extensively operated from 1964 to 1969.

12 Following the MSRE, research continued on 13 the Molten Salt Breeder Reactor and the Denatured 14 Molten Salt Reactor. The DMSR introduced two 15 innovations critical to the commercial viability of 16 MSRs. First was the use of low-enriched uranium as 17 the fuel source and a once-through fuel cycle 18 enhancing proliferation resistance.

19 After a period of dormancy, interest in 20 MSRs was renewed in the early 2000s as part of the 21 Generation for Nuclear Reactor initiative. ONRL 22 subsequently developed the SM-AHTR concept, which 23 introduced the concept of the cartridge core design as 24 a key innovation.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

12 In 2012, Terrestrial Energy was founded to 1

build upon these advancements, incorporating the use 2

of standard assay LEU once-through fuel cycle and the 3

integral core architecture into the IMSR core unit.

4 The successful operation of the MSRE validated the 5

feasibility of liquid-fueled MSRs. However, there are 6

significant design differences between the MSRE and 7

the IMSR, like the advancements in the fuel cycle 8

strategy, safety, and commercial deployment 9

considerations.

10 The IMSR plant is designed to provide 11 high defense customized co-generation for industrial 12 applications. It consists of two distinct facilities:

13 the nuclear facility which houses the reactor and is 14 subject to nuclear regulation and the thermal and 15 electric facilities or a separate non-nuclear facility 16 that converts thermal energy into industrial heat or 17 electricity.

18 The nuclear facility labeled A on this 19 slide follows a standardized design and operates 20 independently from a thermal electric facility. In 21 this dual IMSR configuration shown on this slide, it 22 produces 884 megawatts of thermal energy at a supply 23 temperature of 585 degrees Celsius.

24 MEMBER HALNON: Darren, this is Greg.

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13 Before you get too far, what do you mean by 1

standardized? I mean, this is a nonstandard design.

2 Are you talking about the building layouts, the 3

control room and that sort of thing, is standard or --

4 MR. LOVE: The standard IMSR design so --

5 MEMBER HALNON: Standard IMSR. Okay.

6 MR.

LOVE:

With the

IMSR, the 7

configuration or the site-specific configuration would 8

occur in the thermal and electric facility, but the 9

nuclear facility would be standard amongst all 10 designs.

11 MEMBER HALNON: Keep in mind this is our 12 first interaction with this. I know you've done a lot 13 in Canada and whatnot, but we don't know what standard 14 is yet.

15 MR. LOVE: Terrestrial Energy standardized 16 design.

17 MEMBER HALNON: Okay. Thanks.

18 MR. LOVE: Thermal electric facility 19 labeled as B is a non-nuclear installation that 20 receives thermal energy from the two IMSR core units 21 and can generate 822 megawatts of thermal input or 390 22 net of electrical power or a flexible combination of 23 heat and electricity based on customer needs.

24 Additionally, the IMSR nuclear power plant can 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

14 incorporate molten salt, thermal energy storage and 1

buffering, enhancing the load-following capability, 2

and optimizing commercial performance. The end use of 3

IMSR-generated power could be any industrial facility 4

providing heat, electricity, or a combination of both.

5 This slide presents the major buildings of 6

the IMSR plant. Within the nuclear facility, there 7

are two primary structures: the reactor auxiliary 8

building (RAB) labeled RAB 1 and RAB 2 and the common 9

control building (CB). Each RAB houses a single IMSR 10 core unit, along with its necessary nuclear and 11 support systems to transfer heat from the reactor to 12 the thermal electric facilities. These systems 13 include the IMSR core unit, the heat transport 14 systems, the process and emergency cooling systems.

15 The control building is centrally located between the 16 two RAB structures and contains the main control room 17 for operating both core units in RAB 1 and RAB 2.

18 The thermal electric facility is located 19 outside the nuclear facility perimeter. It consists 20 of a turbine building for each of the operating core 21 units and its corresponding RAB.

22 Based on commercial requirements, the 23 turbine building and steam generation building may 24 feature different heat transport configurations. For 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

15 electrical generation applications, a salt-to-water 1

steam generation system will produce super-heated 2

steam to drive a non-nuclear industrial steam turbine 3

and conventional power equipment. The turbine 4

building also contains the feedwater, steam, and 5

electrical systems for heat and power generation.

6 Located within each RAB or auxiliary 7

building, there is a single operating IMSR core unit.

8 The IMSR core unit is a graphite-moderated thermal 9

spectrum and has a replaceable core unit on a seven-10 year replacement. It uses standard assay low-enriched 11 uranium and is a liquid fuel molten salt reactor. It 12 uses eutectic fluoride-based salt as both the fuel and 13 the coolant.

14 MEMBER PETTI: Just a question. What's 15 the power density?

16 MR. LOVE: Power density --

17 MEMBER PETTI: Of the reactor, the core --

18 MR. LOVE: So each core produces 442 19 megawatts thermal.

20 MEMBER PETTI: The power density could, 21 could trigger --

22 MR. LOVE: Fair enough. I would say that 23 we'll come back to you on that question.

24 MEMBER PETTI: I mean, light water 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

16 reactors sit at one number. I'm just trying to put it 1

in the spectrum.

2 MR. LOVE: The IMSR core unit includes the 3

integrated primary pumps, along with emergency heat 4

removal systems within the IMSR unit. The IMSR design 5

includes a passive negative temperature reactivity 6

coefficient that passively controls the operation of 7

the core unit.

8 Within the simplified flow diagram, on the 9

left-hand side, it shows the IMSR core unit. Molten 10 salt is circulated around the IMSR core unit through 11 the integral pumping system through the graphite core 12 to generate fission heat, which transfers the heat 13 through the primary heat exchangers to a secondary 14 coolant system, or SCS, which utilizes a non-nuclear 15 fluoride-based secondary salt loop.

16 Heat is transferred from the SCS to the 17 tertiary salt loop where site-specific design 18 configuration allows for different options for power 19 generation ranging from electrical generation for both 20 on-and off-grid applications, process heat 21 requirements, and grid stabilization programs such as 22 backup power generation sources such as wind and 23 solar.

24 I'll turn it over to --

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17 MEMBER PETTI: Just another question.

1 What's the pressure of the secondary loop?

2 MR. LOVE: The secondary loop is slightly 3

higher than the primary loop.

4 MEMBER PETTI: In the atmospheric.

5 MR. LOVE: In the atmospheric.

6 MEMBER PETTI: Because we've had other 7

designs come in the issue of a steam generator --

8 because I'm assuming that steam pressure is pretty 9

high.

10 MR. LOVE: So in the secondary salt loop, 11 the SCS is a fluoride-based salt, so going into the 12 IMSR is fluoride salt, a near atmosphere --

13 MEMBER PETTI: I'm saying in the steam 14 generator, right, that steam is pretty high pressure 15 to feed the turbine.

16 MR. LOVE: Yes.

17 MEMBER PETTI: If there were steam 18 generator tube break, high-pressure steam would come 19 back into the secondary loop and, if it's not designed 20 for high pressure, it could cause a failure. That's 21 the safety issue.

22 MR. LOVE: Oh, you can't see my notes 23 there, so we have the primary heat exchanger inside 24 the IMSR core unit. We have a secondary heat 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

18 exchanger which translates the secondary non-nuclear 1

fluoride salt to a tertiary loop, and that tertiary 2

loop then goes through -- there's a --

3 MEMBER PETTI: Okay. So it's the tertiary 4

loop then.

5 MR. LOVE: The tertiary loop there, yes.

6 MEMBER PETTI: Okay.

7 MR. LOVE: So you have two heat exchangers 8

between the water and the salt loop or the steam 9

generation system. And the steam generation system 10 outside the nuclear facility would be in the thermal 11 electric facility and would be sufficiently protected 12 from --

13 MEMBER ROBERTS: A similar question on 14 this figure. This is Tom Roberts. The tertiary salt 15 loop is not shown as feeding the steam generator. Is 16 that also a tertiary salt loop that feeds the primary 17 and the steam generator?

18 MR. LOVE: Yes. On this slide, it's 19 trying to show different configurations, potential, 20 so, yes, it would be the tertiary salt loop goes from 21 the secondary heat exchanger to the steam generation 22 heat exchanger in the case of pure electrical power 23 generation.

24 MEMBER ROBERTS: So in Dave's question, it 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

19 looks like the issue would be a steam generator tube 1

leak which then feeds back to the secondary heat 2

exchanger, which could feedback to the primary heat 3

exchanger to something --

4 MEMBER PETTI: If they're not designed to 5

handle the pressure. You get this propagation, right.

6 MR. LOVE: Yes, absolutely.

7 MEMBER PETTI: Before you move on, just 8

another question. I don't know if we're going to move 9

into something else. Obviously, I've got some 10 questions on the design.

11 DR. BLEY: This is Dennis Bley. Along 12 that same line, the secondary heat exchanger, I know 13 this is just a cartoon, but what would appear to be 14 the shell side that holds the salt for the tertiary 15 loop, is that common to all three of those paths to 16 the steam generator to the process heat and to the 17 grid services?

18 MR.

AKSTULEWICZ:

This is Frank 19 Akstulewicz. I'm not sure I understand your question.

20 Could you try to explain it again or your question 21 again?

22 DR. BLEY: From the secondary heat 23 exchanger, there are three that goes out. One goes to 24 the steam generator heat exchangers, one goes to what 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

20 you call processing uses, and the third one goes to 1

grid services. Is the salt that's moving through 2

those three loops, it's common inside the secondary 3

heat exchanger; is that right?

4 MR. AKSTULEWICZ: Sorry. The figure 5

showing potential different configurations all at the 6

same time, you would likely -- different applications 7

are shown here, so it's more of a pictorial 8

representation. You wouldn't have all --

9 DR. BLEY: Oh, well. We'll see the 10 details later. Go ahead.

11 MR. AKSTULEWICZ: Okay. But what you're 12 saying is is the configuration would be one of these 13 three choices.

14 MR. LOVE: Yes.

15 DR. BLEY: Oh, okay. You wouldn't have a 16 situation where you'd have multiple uses there. Okay.

17 MR. LOVE: Yes, exactly.

18 MEMBER PETTI: In terms of the core life, 19 I assume it's the graphite that's limiting.

20 MR. LOVE: Correct.

21 MEMBER PETTI: Do you know what the damage 22

-- I'm assuming it's sort of centerline, you know, in 23 the center of the core where the damage is the 24 greatest, at least that's what's causing the --

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21 MR. SMITH: For the record, it's Bill 1

Smith from Terrestrial Energy. Yes. The graphite is 2

assumed to last seven years based on its turnaround 3

and crossover point being seven years. We have 4

actually --

5 MEMBER PETTI: So, yes, I know about 6

graphite. So what's the BPA that you're reaching?

7 MR. SMITH: Above 21.

8 MEMBER PETTI: In seven years. Okay. And 9

so your -- its limit crosses back from zero to zero.

10 There's different criteria if you go back in time with 11 graphite.

12 MR. SMITH: Yes, there are.

13 MEMBER PETTI: Okay.

14 MR. AKSTULEWICZ: Okay. Thank you, 15 Darren. I'm going to take over the rest of the public 16 presentation. My name is Frank Akstulewicz. My 17 history has been a bachelor's degree in nuclear 18 engineering from Penn State. I came to work for 19 Bechtel Power Corporation in their Gaithersburg office 20 back in the early 70s. I was involved in the 21 construction of the Calvert Cliffs and Grand Gulf 22 facilities.

23 From there, I moved on to the NRC and I've 24 spent 42 years in service with the NRC in a number of 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

22 positions across the board, including Senior Executive 1

Service in which I was the deputy director or the 2

director for new reactor licensing for ten years. I 3

was in place when we were doing all the COL and design 4

certification licenses under Part 52.

5 I spent two terms or, I guess, sessions 6

I'll call them with two different commissioners as 7

technical assistants. One was with Commissioner Jeff 8

Merrifield, and I retired from Commissioner Annie 9

Caputo's office in 2019. Since that time, I've been 10 working with Terrestrial as their licensing manager 11 facilitating their regulatory engagement activities.

12 So the next slide talks a little bit about 13 what we have been doing. John mentioned it earlier, 14 we're been actively engaged with the NRC with white 15 papers, technical reports, and topicals. Some of them 16 are listed there. John mentioned we had eight papers 17 submitted. I went back and checked; that's actually 18 right. It's nice to know.

19 We found the process of submitting white 20 papers first before going to topicals or technicals to 21 be very valuable. The engagement with the staff 22 highlights a number of issues that we can facilitate 23 or simplify to provide the review process being much 24 simpler for them. So it's been very successful to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

23 this particular point. And as Simon mentioned 1

earlier, this is the first topical report we have 2

taken to the end. Hopefully, we'll get a final safety 3

evaluation afterwards.

4 Our regulatory process for our risk-5 reduction activities in terms of licensing, we are 6

currently engaged in pursuing a standard design 7

approval under Part 52. That is the process we are 8

engaged in. We believe it provides us the best 9

capabilities to transition. If an opportunity for a 10 construction permit would raise, we can convert the 11 information we're developing directly into a CP 12 application and move forward without any interruption 13 going forward.

14 So next slide, please. So, again, back to 15 the pre-application activities, well, first, I guess 16 the most important thing there is the third bullet 17 which highlighted the fact that we were one of the 18 first designs to engage with the Canada Nuclear Safety 19 Commission and a joint review. That was on our 20 postulated initiating events technical report. We 21 found that very successful in terms of highlighting 22 the unique differences between our regulatory 23 frameworks, but it also prepared us in terms of 24 providing information that would be useful in actually 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

24 converting the document to a topical report. John 1

mentioned that we have that report in the moment. It 2

does reflect lessons learned as an appendix to that 3

topical report, and we're moving forward with that 4

review.

5 A highlight that Simon didn't mention, but 6

the IMSR has completed phase one and phase two of 7

their vendor design review process with a positive 8

outcome. So that, again, provided another measure of 9

rigor with respect to understanding the design going 10 forward and providing insights as to where additional 11 work needs to be done.

12 We are engaged with IAEA. Our safeguards 13 activities are using the IAEA state standards. We are 14 also engaged with IAEA on a number of consultancy 15 efforts going forward.

16 Okay. So getting into the development 17 process for the topical report. One of the 18 interesting things that we learned as part of this 19 process is that fundamental safety functions in Canada 20 and the U.S. are essentially the same. They may call 21 them a little different, but, for all intents and 22 purposes, the three primary ones that are listed there 23 are identical between the two regulatory frameworks.

24 Canada does have a couple more that they 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

25 add in, like their safety function of shielding and 1

there's one for monitoring. Those are reflected in 2

our classification of components activities. In terms 3

of whether they will be safety related or not, we'll 4

get into that discussion perhaps a little later this 5

morning. But for all intents and purposes, that is 6

the starting point for our PDC development.

7 As the chairman mentioned, our 8

requirements for U.S. license applications under 9

52.137, specifically for standard design approval 10 which is, again, our regulatory approach, and the 11 Regulatory Guide 1.232 is the guidance for developing 12 non-LWR principal design criteria that we used or 13 followed for this particular process.

14 MEMBER PETTI: Just a question. You said 15 that PDC are requirements for the U.S. Are they not 16 requirements in Canada?

17 MR. AKSTULEWICZ: No, they're not.

18 MEMBER PETTI: Okay. Interesting.

19 MR. AKSTULEWICZ: Just as a quick note, 20 but the Canadian exercise focuses on the safety 21 functions. They don't have specific design criteria 22 that you have to follow or develop.

23 CHAIR PALMTAG: This is Scott Palmtag.

24 Since we're talking about the Canadian, can you 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

26 describe exactly what that means, Canadian phase one 1

and phase two?

2 MR. AKSTULEWICZ: Bill will take that one.

3 MR. SMITH: This is Bill Smith again. So 4

Canadian Nuclear Safety Commission offers vendor 5

design review phase one and phase two as a pre-6 licensing, so it's called the vendor design review.

7 They have 19 criteria against which they measure the 8

technology as to technology vendors, not licensees 9

normally. And those criteria go from plant layout to 10 decommissioning and everything in between. And then 11 it's passed against the Canadian regulations, which 12 don't include design criteria but safety functions, as 13 Frank has said.

14 Phase one is a general sort of perspective 15 do you have a clue and does your design have any 16 chance of meeting the Canadian requirements, and then 17 phase two just goes into deeper and deeper detail on 18 each of the 19 criteria. They report back on it. We 19 got their report in April of 2023, and the conclusion 20 is no fundamental barriers to licensing so long as you 21 continue to execute the design the way in which you 22 said under a quality standard and you continue to do 23 the R&D as you said and marry the two obviously; and 24 if you continue that work, then this technology, as 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

27 you've described it, is licensable. And there are 1

some other elements to it.

2 CHAIR PALMTAG: So it's a pre-application 3

stage.

4 MR. SMITH: Pre-application.

5 CHAIR PALMTAG: How would that relate to 6

the NRC? It would start at the white paper stage.

7 MR. SMITH: Probably a little beyond white 8

paper. To some extent, if I can assess it, topical 9

technical reports -- sorry. A little beyond white 10 paper, more topical technical reports.

11 The NRC and CNSC conducted a study of one 12 of our processes, PIE, four years ago, so there was 13 some coming together between Canadian and NRC on that 14 particular topic. You know, just --

15 CHAIR PALMTAG: I'm just trying to 16 understand how the --

17 MR. SMITH: Yes. So it's --

18 (Simultaneous speaking.)

19 CHAIR PALMTAG: -- Canadian stage versus 20 21 MR. SMITH: -- more technical topical 22 report as opposed to white paper. It's beyond white 23 paper for sure.

24 CHAIR PALMTAG: So you said the Canadians 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

28 are probably slightly ahead of the NRC in the reviews?

1 MR. SMITH: In the review of this 2

particular technology, yes, but you --

3 CHAIR PALMTAG: Okay. Thank you.

4 MEMBER SUNSERI: So I think you touched on 5

something, while we're talking about Canadians. I 6

know the U.S. NRC has a memorandum of understanding 7

with the Canadian CNS about accepting certain 8

technical explanations or whatever. So have any of 9

your topical reports been accepted by Canada and are 10 part of the MOU with the U.S.?

11 MR. AKSTULEWICZ: So Canada does not 12 review topical reports.

13 MEMBER SUNSERI: Okay.

14 MR. AKSTULEWICZ: That's not part of their 15 process. They will review design information, they 16 will review information associated -- they will do 17 audits if they want, but, as a structure, there's not 18 a process in place for topical reports.

19 MEMBER SUNSERI: But Bill was describing 20 something that was part of it, though, right?

21 MR. AKSTULEWICZ: So my understanding, and 22 Bill can correct me if I'm wrong, think of the vendor 23 design review as a 50,000-foot level construction 24 permit application where it highlights the details of 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

29 the systems, the engineering, to the degree that they 1

can. For example, an example I was thinking when the 2

chairman was asking a question was the QA. They do a 3

pretty extensive review of the QA system too their 4

standard for quality assurance. It's not the same as 5

Appendix B or NQA-1. They have their own CSA 6

standard.

7 But they look at that to see if there is 8

a weakness in their quality assurance oversight, so 9

it's more than just a white paper. I mean, they look 10 at the procedures and stuff, too, to make sure that 11 it's implemented appropriately.

12 MEMBER SUNSERI: You're probably wondering 13 why we're asking all these questions, at least I don't 14 know why but -- why I'm asking them. If there's any 15 possibility that something has been reviewed by the 16 Canadians and may not come before us because it's 17 already been accepted or something, that's kind of 18 where my head is going on all this.

19 MR. AKSTULEWICZ: Yes. That will be the 20 case with the PIE topical report where this would be 21 the second time that the staff, maybe even the third 22 time that the staff, we have seen that document 23 through its iterations because it started out as a 24 white paper, then it went to a topical report after 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

30 the evolution of the review as part of the joint --

1 and there's a joint report, right. So both regulators 2

put out their findings in terms of issues that they 3

still identified as part of their review that needed 4

to be resolved, so our topical report speaks to the 5

findings within that joint report moving forward to 6

show how we evolved our process to align with feedback 7

from both regulators.

8 MEMBER SUNSERI: You used an acronym for 9

that? What is that?

10 MR. AKSTULEWICZ: Oh, the postulated 11 initiating events, PIE.

12 MR. SMITH: Bill Smith again just to 13 clarify. That document sits inside our engineered 14 system and has gone through three revisions now, 15 thanks to both regulators and, of course, our own 16 feedback. So the document sits there as part of the 17 engineering basis, as well. And I can't imagine a 18 thing that would have been, currently anyways, 19 reviewed in Canada that would not ultimately then get 20 reviewed by the NRC staff, as well.

21 MEMBER HARRINGTON: This is Craig. Just 22 to be clear, on some of the reviews, there was this 23 joint project. Are your efforts pursuing both 24 Canadian and NRC approval, is that both ongoing?

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31 MR. SMITH: The Canadian one is not 1

ongoing. We stopped it at the end of vendor design 2

review phase two. It would only start again if there 3

was actually a license application in Canada, which is 4

not likely in the near term. So, right now, the focus 5

is to continue the stream in our --

6 MEMBER HARRINGTON: Okay. Thanks.

7 MR. AKSTULEWICZ: Those are all good 8

questions, and feel free to ask. We're here to 9

provide insight and answer your questions to help you 10 understand the design, obviously, and what we've done 11 and where we're going.

12 Okay. The next slide that is up is the 13 general process that was used to build the principal 14 design criteria document. As you are probably well 15 aware, because you've probably seen other topical 16 reports on principal design criteria, the starting 17 point is Regulatory Guide 1.232 that contains several 18 sets of general design criteria, including those that 19 are not specific to technology, and then appendices to 20 that regulatory guide are specific to certain types of 21 technologies.

22 The key point here was you start at those 23 starting points, and then you try to understand what 24 the safety basis for each of those principal design 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

32 criteria that are in the reg guide, what is the safety 1

function they're trying to fulfill and why they're 2

important. Then you start looking at the other 3

reference sets to see how well they match up with the 4

technology-specific requirements for SSCs that are 5

unique to what would be the IMSR in our particular 6

case and then look at how or if you would need to 7

modify the specific principal design criteria that are 8

in the regulatory guide to align with your specific 9

technology.

10 After doing rather exhaustive review of 11 the details and the general guidelines, it turns out 12 that the sodium fast reactor reference set is the 13 closest set for the IMSR. It's not aligned in all 14 cases, but it served as a really good starting point.

15 And, obviously, we had to take departures from that 16 reference set to be specific to our technology and, 17 obviously, we submitted those departures to the staff 18 and had them reviewed as part of the draft safety 19 evaluation, you know, finds them acceptable at the 20 moment.

21 MEMBER PETTI: Just a quick question. I'm 22 sure you must be aware of the ANS has a set of 23 criteria.

24 MR. AKSTULEWICZ: Yes, I was on that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

33 committee.

1 MEMBER PETTI: So, I mean, similar then if 2

you line them up to what you ultimately have --

3 MR. AKSTULEWICZ: Yes. There are some 4

unique differences. For example, the ANS standard, 5

their containment is built around a functional 6

containment design. We do not use a functional 7

containment. We have a leak-tight, you know, metal 8

containment, so that's obviously a variant right there 9

off the bat, right.

10 But the most important thing, and this is 11 one of the challenges that we had as part of that 12 committee work, was they employ a SARRDL, and what is 13 that? A specified acceptable radiological release 14 limit. We did not employ that, and that's part of our 15 discussion later this morning. But I can say that one 16 of the reasons is that a SARRDL is calculated 17 depending on what day of the week it is and whatever 18 meteorological condition you have because it's the 19 value that would reach a certain regulatory criteria 20 if you got a release. Well, depending on how the wind 21 blows and the rain or whatever, those numbers are 22 different day to day. And the other thing is you 23 won't know that you've exceeded it until you actually 24 have a release that exceeded it.

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34 So we chose not to go that way. We chose 1

to monitor parameters that would tell us where we are 2

in the process rather than waiting until the end to 3

figure out whether we've over-exceeded our limit. And 4

we'll get into that a little more in the proprietary 5

session.

6 MEMBER ROBERTS: So if I follow up on 7

that, the presentation mentioned LMP, licensing 8

modernization. I assume you're not using any of the 9

LMP concepts or --

10 MR. AKSTULEWICZ: Right now, the plan is 11 to not use any of the LMP concepts. We are or will be 12 risk informed. You have to use some PRA information 13 when you're developing your postulated initiating 14 events, but we do not believe that it's necessary to 15 use the LMP methodology to reach a successful safety 16 outcome, so that's kind of where we are.

17 MEMBER ROBERTS: Okay. Thank you.

18 MR. AKSTULEWICZ: Okay. Again, the 19 process here, we submitted an initial white paper. We 20 got feedback that we have turned into the topical 21 report. The resolution of that feedback is in the 22 topical report. We did take departures from the 23 standard language, and we can go through those in a 24 little more detail in the following session.

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35 We could not adopt all of the language as 1

it was written. The NRC did come out and do a 2

regulatory audit of very specific topics, and I think 3

we'll spend a lot more time on that this -- I keep 4

saying this afternoon but later this morning.

5 And so, as a summary, bottom line is, of 6

the 64 principal design criteria that are in the 7

reference set, and that would be the sodium fast 8

reactor reference set, we were able to adopt 31 of 9

them without -- I'm sorry, 20-something of them.

10 That's not the right number. No, that's not right.

11 I think the number is 28 or 23 -- 26, right. And this 12 was a stumbling point, so there's a little confusion 13 here because we thought that we were not modifying a 14 couple of them, but, during the final phases of our 15 review with the staff, they said, well, you're 16 changing this little word here, so that it's such a 17 minor edit, but it is a change so it's a change. So 18 the figures there aren't accurate.

19 So the staff's figures in the safety 20 evaluation are accurate. We said 26, and I think 21 it's, again, it's like 26 that were modified and then 22 10 that were not adopted in their entirety. And the 23 10 that were not adopted, I think, are important to 24 understand, and we'll have that discussion in a later 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

36 session.

1 MEMBER HALNON: This is Greg. Did you 2

have to do any new ones any different?

3 MR. AKSTULEWICZ: So that's a great 4

question. The answer is, no, we did not need to 5

identify a new one. There was a lot of discussion 6

about whether we needed one for graphite, and I'm sure 7

we'll have more discussion of that this afternoon. We 8

believe that the way we phrased our principal design 9

criteria to focus on material limits and performance 10 requirements simplifies that, so we don't need a 11 unique principal design criteria just for graphite.

12 CHAIR PALMTAG: I just wanted to state for 13 the public record that most of these modifications, as 14 you mentioned, were very small. This literally 15 changed sodium to molten salt, but there are quite a 16 few that we're going to have questions on, and we'll 17 have significant questions when we go into the closed 18 session.

19 MR. AKSTULEWICZ: Correct, yes. Again, 20 good point, chairman -- thank you -- is that a lot of 21 the modifications weren't substantive. Another 22 example is changing the language from primary coolant 23 to a fuel cell boundary, which is the same but just 24 different vernacular. So it's those types of 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

37 simplifications that highlighted a lot of the changes 1

where modifications were made.

2 I think that ends my presentation. So 3

I'll take any more questions if folks have them.

4 CHAIR PALMTAG: Any questions? Any 5

questions online? All right. Let's take a quick two-6 minute break and switch out the NRC.

7 (Whereupon, the above-entitled matter went 8

off the record at 9:15 a.m. and resumed at 9:18 a.m.)

9 MR. ROCHE: Good morning, chairman and 10 members. My name is Kevin Roche. I'm a project 11 manager in the Advanced Reactor Licensing Branch 2.

12 I'm very late in the game for this project, so there's 13 a number of folks that I'll touch on later who really 14 contributed greatly, made a greater contribution than 15 I did to where we are today, including members of the 16 staff. We have Matt Gordon and Ben Adams will be 17 online and were not able to attend in person. They'll 18 be doing, along with Hanh Phan, the majority of the 19 presenting.

20 So I'll move on to this portion. I'll 21 talk briefly about the chronology. We've had this 22 topical for a bit of time, and, hopefully, this will 23 be kind of a capstone and we can move forward, as was 24 discussed in a number of other topicals and technical 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

38 reports that Terrestrial has.

1 And now I'll turn it over to Hanh Phan who 2

will kind of walk us through the open portion of the 3

staff's presentation.

4 So as I mentioned, there's a number of 5

folks who contributed to the review of this topical.

6 As I mentioned, Matt Gordon and Ben Adams will be two 7

of the principal reviewers and are both online to 8

answer your questions. Ben Parks is also online to 9

help out. Adrian Muniz, Michelle Vega Rodriguez, and 10 Lucieann were all project managers or have all been 11 project managers during this time, so they all 12 contributed much more so than I did to the review.

13 Moving on, we initially received this 14 topical in 2023, held on it, went back and forth with 15 Terrestrial. They submitted two different subsequent 16 revisions, and here we are today. We issued the draft 17 around the 20th of February, and we're here in front 18 of you all.

19 And with that, I'll turn it over to Hanh.

20 MR. PHAN: Thank you, Kevin. Good morning 21 ladies and gentleman. My name is Hanh Phan, senior 22 PIE -- and also the technical lead for the -- project.

23 I spent almost 40 years in nuclear and PRA, half of 24 those in the professional labs and nuclear power 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

39 plants, the other half at the NRC.

1 In the next two slides, I will briefly 2

outline the purpose of the TEUSA PDC topical report.

3 The staff reviewed strategy, key regulations, and 4

relevant guidance. The main purpose of the technical 5

report is to establish criteria to support -- and 6

future IMSR license applications while it will 7

strengthen compliance with the regulatory requirements 8

of 10 CFR Part 50 and 52 associated with the PDC.

9 The staff reviewed strategy ensuring 10 compliance with the regulatory requirements. Two, 11 assessing conformance with the staff guidance, 12 specifically Reg Guide 1.232

guidance, with 13 developing principal design criteria of non-light 14 water reactors. Three, evaluating deviations from Reg 15 Guide 1.232 on IMSR design features. And, four, 16 assessing the applicability of Reg Guide 1.232 on IMSR 17 design features.

18 Next slide, please. This slide identifies 19 the regulation relevance to the PDC in the context 20 with the provisions in 10 CFR Parts 50 and 52, 21 applications for CP, OL, DC, COL, SDA, and MLs. They 22 all must submit PDC for their proposed facilities. The 23 specific regulation attached to the PDC are provided 24 in 10 CFR 50.34, 52.47, 52.79, 52.127, and 52.157.

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40 Since TEUSA intends to update the standard design 1

approval for the IMSR core units. Therefore, this is 2

subject to 10 CFR 52.157(a)(3)(I).

3 Additionally, 10 CFR Part 50 is also 4

applicable to -- which specifies requirements for the 5

scope and content of the PDC for non-LWRs.

6 Next slide, please. Reg Guide 1.232 7

provides guidance for non-standard designers, 8

applicants, and licensees in developing PDC for non-9 LWR design as required by the regulation.

10 As mentioned in the topical report, TEUSA 11 chose to use sodium fast reactors design criteria in 12 Reg Guide 1.232, Appendix B -- design criteria with 13 some modification. In the closed session discussion, 14 the staff specifically removed them.

15 This slide also mentions the draft ANS 16 20.2-2023. Just to clarify that this ANS guidance is 17 still undergoing endorsement as the basis for this TR 18 evaluation.

19 With that, I will turn it to Ben for the 20 IMSR PDC overview.

21 MEMBER SUNSERI: Just a quick question.

22 So the applicant mentioned they had to take, for my 23 words, an exception to some of the examples. I 24 thought we were building a reg guide that was 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

41 technology inclusive. I guess we missed molten salt 1

reactors that have the reference to sodium or a sodium 2

fast reactor standard. Am I about face or am I 3

missing something here?

4 MR. SEGALA: Yes, this is John Segala from 5

the NRC staff. I was just going to say that, yes, 6

back when we developed Reg Guide 1.232, it was a large 7

effort. We looked at developing the advanced reactor 8

design criteria which were general, and then we 9

developed high-temperature gas-cooled reactor design 10 criteria and sodium-cooled fast reactor design 11 criteria, but we did not, at that time, develop molten 12 salt reactor criteria because, back then, there wasn't 13 a whole lot of information on molten salt reactors in 14 terms of our competence and being able to develop 15 design criteria at that time. But as they mentioned, 16 since then, ANS is working on that and looking at 17 revising the reg guide to add some criteria of formal 18 salt reactors, but we did not do that at the time.

19 Does that answer your question?

20 MEMBER SUNSERI: Yes, it does. Thank you.

21 MR. SEGALA: And I'm just going to add 22 that the reg guide is, you know, not a requirement.

23 It's one acceptable way of coming up with your 24 principal design criteria, and it was technology 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

42 inclusive but it was based on the certain designs at 1

the time that we were looking at. So the reg guide 2

talks about the designs that we considered when we 3

developed those, but it was always anticipated as a 4

developer uses the reg guide to help develop their 5

principal design criteria that they would have to look 6

at the unique aspects of their design and customize 7

the PDCs to be appropriate for their unique design.

8 MEMBER SUNSERI: Okay. I mean, that's 9

kind of what I was thinking. I mean, the appendices 10 are just examples of how the criterion were applied, 11 so they could have just applied the criterion and not 12 have to take exception, right?

13 MR. SEGALA: To the extent it applies to 14 their specific design, you know, because these were 15 done based on the set of designs that we considered 16 back when we developed the reg guide. And so, you 17 know, you can only do so much based on what you know 18 at the time, but there's a lot of different, even 19 though you do it for the technology, there's a lot of 20 nuances and uniqueness as to specific designs that 21 they would have to customize that.

22 MEMBER SUNSERI: I'm not throwing stones 23 with these guys. They were before you for ten years.

24 I mean, that's well within the envelope of when the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

43 reg guide was developed.

1 MEMBER ROBERTS: Hey, Matt, I think I 2

agree with your thought. We had similar questions 3

when we reviewed the heat pipe microreactor PDC 4

topical a few months ago, and then also there's no 5

appendix in the reg guide for heat pipe reactor. And 6

they based everything on the ARDCs, the high-level 7

principles, and then they looked at the individual 8

examples for guidance. But I think that's the same 9

thing they did here, so the term exception to SFR 10 criteria probably isn't this number, I'm thinking.

11 The reality, they just had to find a different way to 12 meet the advanced reactor design criteria, which is 13 generically acknowledged and explicitly stated to 14 apply this technology. Yes, it was a good point.

15 MEMBER SUNSERI: Yes, I'm not trying to 16 belabor the point.

We're all looking for 17 inefficiencies in the regulatory process, and so, you 18 know, I'm just trying to wrap my head around where 19 they are.

20 DR. BLEY: This is Dennis. Just 21 remembering back and supporting what John was saying, 22 when they first brought that reg guide to us, I think 23 one of the reasons is they picked the ones where they 24 had substantial experience and expertise in-house to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

44 do as their first examples and told us at the time 1

they intended to extend it but they wanted to get it 2

out as fast as they could. I think that makes sense.

3 Since then, there's been an awful lot of 4

work at NRC looking at other kinds of designs, 5

including molten salt and development of the codes to 6

support their reviews, too.

7 CHAIR PALMTAG: This is Scott Palmtag. I 8

appreciate, John, that you're looking at Reg Guide 9

1.232 for molten salt. I'm having a little trouble 10 that there seems to bifurcation between the ANS and 11 the Terrestrial because one is going down a functional 12 containment and one is going down a real containment, 13 so I don't know how that's going to work. And even 14 for new technologies, that might be an issue.

15 But one thing I want to mention is I'm 16 kind of troubled by all these PDCs for the Terrestrial 17 are proprietary. It would certainly make this a lot 18 easier if these were PDC that we could apply to 19 different technologies. Is it normal for PDC to be 20 proprietary? I guess not because they're usually from 21 Reg Guide 1.232, at least the ones I'm seeing.

22 MR. ROBERSON: I'm not sure how to answer 23 that. I can say -- this is -- Roberson, I'm a branch 24 chief in IJMU. If you recall the Westinghouse --for 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

45 proprietary and even some of the PDCs we've seen for 1

the high-fission gas reactors, IC100 for instance --

2 it's not uncommon.

3 CHAIR PALMTAG: I guess that's another 4

reason to get, if we can get 1.232 updated for both 5

the heat pipe reactors and the molten salt to kind of 6

get ahead of this before everything becomes 7

proprietary. Just a comment. Thanks.

8 MR. ADAMS: Good morning, everyone. I'm 9

Ben Adams, technical reviewer with the NRC staff. I'm 10 in NRR DANU Technical Branch No. 1. This slide is 11 really just an overview of the PDCs that were chosen.

12 If you've seen the reg guide, this looks familiar.

13 Terrestrial did provide a justification 14 for every single design criteria they chose. We're 15 not going to be going over every single one today 16 because we'd be here for a few days, but we're going 17 to highlight the substantial ones.

18 Next slide, please. Okay. And this slide 19 is an overview of what's in the CT evaluation. I 20 won't spend too much time on this slide either. It 21 starts off with the regulations and the guidance that 22 are relevant, which we just went over a couple of 23 slides ago. And then it highlights some relevant 24 design information, and then it goes into the PDC 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

46 selection.

1 In the safety evaluation, we binned up the 2

discussion based on PDCs with no changes from the reg 3

guide and then ones with minimal terminology changes 4

and then ones with substantial technical changes. And 5

then it goes to the limitations and conditions, which 6

there are a few of, and then the conclusions.

7 Next slide, please. I guess that's it for 8

me.

9 MR. PHAN: Thank you, Ben. So in 10 conclusion --

11 CHAIR PALMTAG: This is Scott Palmtag 12 again. I appreciate we can't go through each one of 13 these, but can you at least tell us the numbers of the 14 ones that may be contentious?

15 MR. ADAMS: We have slides prepared for 16 the ones that I think ACRS will be interested in. For 17 example, I think we have a single slide that just 18 summarizes --

19 CHAIR PALMTAG: Yes, I understand a lot of 20 this is proprietary. But I'm just saying, for the 21 public record, can we at least tell which ones that 22 we're discussing with the main ones?

23 MR. PHAN: Yes. So based on the staff 24

reviews, we identified 26 PDCs in the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

47 quantification, 20 of those with minor -- changes and 1

18 of those important --

2 So in the closed session, the staff would 3

focus on the 18 that would be most important for your 4

information. So, mostly, if you'd like to know which 5

of those, they are PDC 5, 20 - 29, reacting with 6

control systems; PDC 10 on reactor design; PDC 12 on 7

suppression of reactor power -- PDC 19, control rooms; 8

PDC 41 through 43, relevance to the containment 9

atmosphere; and PDC 79, cover and off-gas inventory 10 maintenance. Those will be discussed specific in the 11 closed session.

12 MR. ADAMS: Okay. Thank you, Hanh.

13 CHAIR PALMTAG: So this is Scott. Did you 14 take the PSAR from Abilene Christian University's 15 project in -- to see and compare their PDCs to what we 16 came up with, being that Abilene was really the first 17 molten salt PSAR? So did you have any comparison 18 there that you can talk about?

19 MR. PHAN: We did not, but, Matt, would 20 you please respond to this question?

21 MR. GORDON: Hi. My name is Matthew 22 Gordon. In response, I am not aware of any overlap 23 with the Abilene Christian University PDCs and this 24 review.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

48 CHAIR PALMTAG: Because one of the 1

purposes advertised for ACU was to support the 2

commercialization of molten salt. It would surprise 3

me if you didn't utilize that research in what you've 4

already approved in your PSAR when you looked at this 5

PDC.

6 So maybe that's just a comment. It's just 7

surprising that you wouldn't have used that 8

significant research there, plus it's already been 9

approved by the agency and -- So I'll make some 10 comparisons as we go forward.

11 MEMBER PETTI: And just another question.

12 Are the limitations and conditions proprietary? Can 13 you give us a sense in the open session of what the 14 limitations were?

15 MR. PHAN: Because the language and mostly 16 the, not the design criteria, the language in the PDC 17

-- be more specific --

18 MR. ADAMS: Yes. This is Ben Adams. The 19 limitations in their entirety are not proprietary, but 20 there are some proprietary sentences in there.

21 MR. ROBERSON: This is Grant Roberson, 22 branch chief from DANU. I do want to circle back to 23 the observation made about ACU. If you can confirm my 24 understanding of this, Ben, because you did work on --

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49 does use a -- which has already been noted as one 1

difference from other IMSR, and that would be in 2

consideration -- correspondence of the PDCs. Would 3

you agree with that, Ben?

4 MR. ADAMS: I would agree with that, yes.

5 MEMBER HALNON: But it's a graphite-6 moderated liquid fuel.

7 MR. ROBERSON: I understand. I'm just 8

observing at least one difference with the --

9 MEMBER HALNON: I realize there would be 10 some differences, but there was a lot of experience 11 gained. I assumed you would have went through that.

12 MEMBER MARTIN: Regarding the proprietary 13 nature of the PDCs, I can appreciate, at this stage in 14 the review process, to hold back because of the 15 potential for any of these PDCs to evolve. But there 16 is not a reactor that it serves the public whose PDCs 17 are not otherwise open because, of course, they're all 18 in Appendix A. If I was a member of the public, I 19 would want to know the criteria for which, you know, 20 my neighborhood plant has been designed to. I think 21 that is very important, and I have a hard stop with 22 that.

23 But, again, I can understand there's some 24 evolution in this process and that, you know, that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

50 final decision can be made much later. I would hope 1

that, when it comes time to finalize the safety 2

analysis report, that those PDCs are then open to the 3

public so they can critique them. You know, not 4

everyone is, you know, a nuclear engineer, but there 5

are some. There are some very smart people out there 6

that will care about this.

7 Anyway, I'll throw that out there.

8 MR. PHAN: Thank you, gentlemen. We take 9

your feedback seriously. And in conclusion, to ensure 10 that the PDC are properly developed and 11 implemented, the staff has imposed four limitations 12 and conditions. We're going to present them in the 13 closed session. The staff finds TEUSA provided a 14 sufficient set of PDCs with the IMSR design, subject 15 to the L&Cs. The proposed PDCs established the 16 design, application, construction, testing, and 17 performance design criteria -- to provide reasonable 18 assurance that IMSR could be operated without undue 19 risk to the public. And based on our evaluation, the 20 staff conclusion is -- report, revisions --- is 21 suitable for use in the future IMSR licensing 22 application.

23 So this marks the end of our presentation 24 for the open session. In the upcoming closed session, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

51 we will go into more details on the PDCs that are 1

considered important to -- with that, we will answer 2

any additional questions you may have.

3 CHAIR PALMTAG: Any additional questions 4

for Terrestrial or for the NRC in the open session 5

from the ACRS members or consultants?

6 I think it's time to move on to public 7

comments. We have not received any written comments 8

for this meeting, but I would like to open it up for 9

public comments. If anyone in the public would like 10 to make a comment, please raise your hand and unmute 11 your microphone when it comes time. I can see one.

12 Spencer Toohill. Do you want to go ahead and unmute 13 your microphone?

14 MS. TOOHILL: Yes. Hi, there. Good 15 morning, everyone. Thank you all for the opportunity 16 for the public to ask any questions or comments. My 17 name is Spencer Toohill, and I am with the 18 Breakthrough Institute. And I really just have, 19 hopefully, a simple question. I'm just interested in 20 learning a bit more about what the next steps are 21 here. Obviously, this will transition to the closed 22 session for you all to discuss --

23 CHAIR PALMTAG: I'm sorry, Spencer, to cut 24 you off, but this is for public comments only, not 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

52 questions. If you do have any questions, I'd like to 1

refer you to the Designated Federal Officer, Chris 2

Brown, and his email can be found on the meeting 3

notice.

4 MS. TOOHILL: Okay. Thank you for the 5

redirect. I appreciate it. Thanks so much.

6 CHAIR PALMTAG: Do you have a comment?

7 MS. TOOHILL: No, I just had a question, 8

so I'm all set. Thank you so much.

9 CHAIR PALMTAG: All right. Thank you.

10 Was there another comment? Okay. Seeing none, I 11 think we're going to go ahead and we'll close the open 12 session and we'll move to a closed session. All 13 right. Thank you.

14 (Whereupon, the above-entitled matter went 15 off the record at 9:44 a.m.)

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Terrestrial Energy ACRS Subcommittee March 20th, 2025 Delivering carbon-free thermal and electrical energy Development of Principal Design Criteria for the Integral Molten Salt Reactor (IMSR)

ACRS Subcommittee Meeting - Open Session March 20, 2025

2 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Simon Irish, CEO and Director, Terrestrial Energy William Smith P.Eng, Senior Vice President of Operations and Engineering, Terrestrial Energy Francis Akstulewicz, Licensing Manager, Terrestrial Energy Darren Love P.Eng, Engineering Director, Terrestrial Energy

Introductions

3 Terrestrial Energy ACRS Subcommittee March 20th, 2025 3

Terrestrial Energy ACRS Subcommittee March 20th, 2025 IMSR Technology Overview Licensing Strategy Preapplication Activities Agenda Overview of Topical Report Development Process Conclusions I

II III IV V

4 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Denatured Molten Salt Reactor (DMSR) 2 conceptual design developed at ORNL Key innovation: Use of Low Enriched Uranium (LEU) with a once-through fuel cycle for strong proliferation defenses IMSR is based on MSR technology demonstrated at Oak Ridge National Laboratory (ORNL)

Based closely on molten salt technology demonstrated at ORNL. IMSR is a molten salt reactor that uses:

Fluoride chemistry Under 5% LEU once-through fuel cycle Thermal spectrum Graphite moderator Integral core architecture 1958 -1969 First Molten Salt Reactor (MSR) research program started in the 1950s1 Molten Salt Reactor Experiment (MSRE) at ORNL highly successful and lays foundation for future molten salt reactor designs 1980 2010 Small Modular Advanced High-Temperature Reactor (Sm-AHTR) design, using solid fuel and molten salt cooling 3 Key innovation:

Cartridge core design

>2012 Terrestrial Energys IMSR combines these critical innovations Use of SA-LEU fuel with a once-through fuel cycle Integral core architecture Source: ResearchGate; ORNL; Company 1.

ORNL, Molten Salt Reactor History and ORNL-2474 Quarterly Progress Reports 1958-1976 2.

ORNL, Conceptual Design Characteristics of a Denatured Molten-Salt Reactor with Once-Through Fueling 3.

ORNL, Pre-Conceptual Design of a Fluoride-Salt-Cooled Small Modular Advanced High-Temperature Reactor (SmAHTR)

5 Terrestrial Energy ACRS Subcommittee March 20th, 2025 IMSR Plant is designed to deliver -

behind the fence -

customized cogeneration to industry Standardized dual IMSR Nuclear Facility

• Subject to nuclear regulation

• Standardized, simplifying design and saving costs

• 884 MW (gross) thermal energy production for 585°C supply Prospective industrial cogeneration off-takers

• Chemical and petrochemical plant

• Hydrogen / ammonia / fertilizer plant

• Other industrials requiring clean heat & power Customized non-nuclear Thermal and Electrical facility

• Converts 884 MW (gross) thermal energy from two IMSRs to 585°C 822 MW (net) thermal or 390 MW (net) electric power for commercial supply - or any heat/electric power mix in between

• Can include molten-salt thermal energy storage and buffering to enhance its inherent strong load-following capability for commercial advantage

• Separate Nuclear Facility & non-nuclear Cogeneration Facility Prospective municipal off-takers

• Electric grid

• Desalination Separation of nuclear from thermal and electrical systems allows a standardized reactor design, while giving the end-user the flexibility to use thermal, electric, or both Note: Example is for a dual reactor core IMSR Plant. Scaling up is possible.

End-user heat / power (industry /

grid electric power)

B Non-nuclear Cogeneration Facility (heat / power)

Dual IMSR Nuclear Facility A

A C

C 5

B HEAT POWER Conversion loss HEAT 585°C 822 MWth (thermal) 390 MWe (electrical) 585°C A

Principal flow of energy

6 Terrestrial Energy ACRS Subcommittee March 20th, 2025 IMSR Plant Layout RAB Buildings Reactor Auxiliary Buildings (RAB), each containing an operating IMSR Core-unit and associated nuclear and support systems necessary to transfer heat in the reactor to the associated Thermal Electricity Facility.

Common Control Building Located between the two RAB structures, supports and provides services to both RAB units. Utilizes a common Main Control Room (MCR) for both RAB.

Turbine Buildings Each Turbine Building (TB) contains non-nuclear-grade, industry standard power equipment. The TB houses the Turbine Generator Set (TG), Condenser, and the associated feedwater, steam systems, electrical systems and other required equipment

7 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Graphite Moderated, Thermal Spectrum with Replaceable Core-unit (seven-year cycle)

Standard Assay Low Enriched Uranium <5% Enrichment and On-line Fueling Liquid-Fueled Molten Salt Reactor. The molten salt act as both the Fuel and Coolant Integrated Primary Pumps and Heat Exchanger with Emergency Heat Removal Passive Reactivity Control (negative temperature reactivity coefficient)

IMSR Technology Overview

8 Terrestrial Energy ACRS Subcommittee March 20th, 2025 8

Terrestrial Energy ACRS Subcommittee March 20th, 2025 Preapplication Activities Agenda Overview of Topical Report Development Process Conclusions III IV V

Licensing Strategy II IMSR Technology Overview I

9 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Licensing Strategy Engage NRC with Preapplication Activities

• Regulatory Engagement Plan submitted

• White papers

• Definition of IMSR Core-unit

• Exemptions required under Part 52

• Postulated Initiating Event Methodology (joint CNSC/NRC review)

• Technical reports

• Modeling and Simulation of Off-Gas Source Term

• Topical reports

• Principal Design Criteria for IMSR

• Postulated Initiating Events Methodology Pursue Standard Design Approval under Part 52

• Reduces regulatory risk

• Provides options for conversion to Construction Permit under Part 50

10 Terrestrial Energy ACRS Subcommittee March 20th, 2025 10 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Agenda Overview of Topical Report Development Process Conclusions IV V

IMSR Technology Overview I

Licensing Strategy Preapplication Activities II III

11 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Preapplication Activities US NRC

• IMSR pre-licensing activities with the US - NRC commenced in 2018 with grant support from the U.S. Department of Energy (DOE)

• Several white papers and topical reports have been submitted to and reviewed by the US NRC as part of the licensing engagement plan in the US, including PDC TR

• IMSR was selected by the US NRC and the CNSC for the first cross-border joint review of a high temperature reactor technology Canadian Nuclear Safety Commission (CNSC)

• completed Phase 1 and Phase 2 of the Vendor Design Review (VDR) of IMSR with positive conclusion IAEA

• safeguards-by-design will facilitate future licensing application for the IMSR

• Significant interactions with the IAEA and the CNSC on safeguards-by-design (SBD)

• Valuable feedback from the IAEA is being considered in the detailed design phase

12 Terrestrial Energy ACRS Subcommittee March 20th, 2025 12 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Preapplication Activities Agenda Overview of Topical Report Development Process Conclusions III IV V

IMSR Technology Overview I

Licensing Strategy II

13 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Terrestrial Energy ACRS Subcommittee March 20th, 2025 PDC Development Process Fundamental safety functions in Canada and US are the same

• Control reactivity

• Remove heat from reactor and stored fuel

• Confine radioactive releases so regulatory criteria are not exceeded PDC establish programmatic elements of a license that assure that the fundamental safety functions will be performed PDC are requirements for US license applications RG 1.232 establishes guidance for developing non-LWR PDC

14 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Process for Selecting Initial Set of PDC RG 1.232 contains several sets of general PDC that serve as starting points for technology specific PDC Understand the safety basis supporting the general PDC before selecting the initial starting set of PDC Understand the safety philosophy of the systems, structures and components in the reference PDC set to determine if the specific technology has similar or identical requirements Perform a line-by-line examination of the selected reference set language to the SSCs of the specific technology and the expected safety functions that are to be performed Sodium fast reactor reference set was closest to IMSR technology but not aligned in all cases Departures from reference set criteria must be justified in a licensing basis topical report and be approved by the US regulator

15 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Overview of PDC review and results TE white paper initially submitted to NRC to begin regulatory engagement on PDC development process.

NRC feedback incorporated into topical report and documentation bases.

Departures from RG 1.232 reference set of design criteria are justified and approved by US regulator.

Not all reference set PDC are adopted without modification to make the criteria technology specific.

NRC performed regulatory audit to support their regulatory findings.

Of the 64 PDCs set by the reference RG 1.232:

• 31 were adopted without modification

• 23 were adopted with modifications to reflect IMSR specific design

• 10 were not adopted as not necessary for the IMSR

16 Terrestrial Energy ACRS Subcommittee March 20th, 2025 16 Terrestrial Energy ACRS Subcommittee March 20th, 2025 Preapplication Activities Agenda Overview of Topical Report Development Process Conclusions III IV V

IMSR Technology Overview I

Licensing Strategy II

NRC Staff Review of the Terrestrial Energy USA, Inc.

Principal Design Criteria Topical Report for the Integral Molten Salt Reactor Kevin Roche, Project Manager Hanh Phan, Senior Reliability and Risk Analyst Ben Adams, Nuclear Systems Engineer Matthew Gordon, Materials Engineer Office of Nuclear Reactor Regulation (NRR)

Division of Advanced Reactors and Non-Power Production and Utilization Facilities (DANU)

ACRS Subcommittee Meeting (Open Session)

March 20, 2025

Agenda

• Review chronology

• Topical report (TR) purpose and review strategy

• Safety evaluation (SE) overview

• Conclusions 2

NRC Review Team

• Matthew Gordon, Materials Engineer, NRR/DANU (Technical Lead)

• Christopher Adams, General Engineer, NRR/DANU

• Joseph Ashcraft, Former NRC Staff, NRR

• Hanh Phan, Senior Reliability and Risk Analyst, NRR/DANU (IMSR Project Lead)

• Benjamin Parks, Senior Technical Advisor, NRR/DANU

• Kevin Roche, Project Manager, NRR/DANU (IMSR Project Manager)

• Adrian Muniz, Senior Project Manager, NRR/DANU

• Michelle Vega Rodriguez, Project Manager, NRR/DANU

• Lucieann Vechioli Feliciano, Project Manager, NRR/DANU 3

Review Chronology

• Jun 8, 2020: White Paper containing proposed Principal Design Criteria (PDC) for Integral Molten Salt Reactor (IMSR) submitted (ML20178A457)

• Aug 20, 2020: NRC staff provided comments (ML20304A561)

• Jan 17, 2023: TEUSA IMSR PDC TR, Revision 0 submitted (ML23025A066)

• Feb 17, 2023: TR accepted for review

• Sep 28, 2023: Closed clarification meeting

• Dec 29, 2023: TEUSA IMSR PDC TR, Revision B submitted (ML24053A168)

• Apr 8, 2024: PDC TR audit commenced

• Jul 2, 2024: Audit exited

• Jul 19, 2024: TEUSA IMSR PDC TR, Revision C submitted (ML24204A092)

• Aug 28, 2024: Closed clarification meeting

• Oct 7, 2024: Audit report issued (ML24233A246)

• Nov 4, 2024: Closed clarification meeting

• Feb 20, 2024: NRC staffs draft safety evaluation report issued (ML24339A121) 4

TR Purpose and Review Strategy

• Purpose of TR

• Establish the PDC to support the design/future license applications referencing the IMSR

• Demonstrate compliance with the relevant regulatory requirements of Title 10 of the Code of Federal Regulations (10 CFR) Parts 50 and 52 associated with PDC

• Review strategy

• Ensure compliance with regulatory requirements

• Review conformance with Regulatory Guide (RG) 1.232, Guidance for Developing Principal Design Criteria for Non-Light-Water Reactors

• Evaluate deviations from RG 1.232 in consideration of the key IMSR design features

• Assess applicability of RG 1.232 appendices and guidance to novel IMSR design features 5

Regulations

• In accordance with the provisions of 10 CFR Parts 50 and 52, applicants for a construction permit (CP),

operating license (OL), standard design certification (DC), combined license (COL), standard design approval (SDA), or manufacturing license (ML) must submit PDC for the proposed facility. Specifically, the following regulations pertain to the PDC:

• 10 CFR 50.34(a)(3)(i), which requires, in part, that applications for a CP include PDC for the facility. An OL would reference a CP, which would include PDC

• 10 CFR 52.47(a)(3)(i), which requires, in part, that applications for a standard Design Criteria (DC) include PDC for the facility

• 10 CFR 52.79(a)(4)(i), which requires, in part, that applications for a COL include PDC for the facility

• 10 CFR 52.137(a)(3)(i), which requires, in part, that applications for an SDA include PDC for the facility

• 10 CFR 52.157(a), which requires, in part, that applications for a ML include PDC for the reactor to be manufactured

• 10 CFR Part 50, Appendix A provides requirements on the scope and content of PDC for non-light water reactors (non-LWRs):

• The principal design criteria establish the necessary design, fabrication, construction, testing, and performance requirements for structures, systems, and components important to safety; that is, structures, systems, and components that provide reasonable assurance that the facility can be operated without undue risk to the health and safety of the public.

6

Guidance

• RG 1.232, Guidance for Developing Principal Design Criteria for Non-Light-Water Reactors (ML17325A611)

• Appendices provide example advanced reactor design criteria

• Draft American National Standards Institute (ANSI)/American Nuclear Society (ANS) ANSI/ANS 20.2-2023, Nuclear Safety Design Criteria and Functional Performance Requirements for Liquid-Fuel Molten Salt Reactor Nuclear Power Plants

• The NRC staff is in the process of reviewing ANSI/ANS 20.2-2023 for requested endorsement 7

IMSR PDC Overview

• TEUSA established the IMSR PDC as follows:

• Section I - Overall Requirements (DC 1-5)

• Section II - Multiple Barriers (DC 10-19)

• Section III - Reactivity Control (DC 20-29)

• Section IV - Heat Transport Systems (DC 30-46)

• Section V - Reactor Containment (DC 50-57)

• Section VI - Fuel and Radioactivity Control (DC 60-64)

• Section VII - Additional (DC 70-79) 8

Safety Evaluation Overview

• Regulations and guidance

• IMSR design features (informational)

• IMSR PDC

• PDC with no changes to the design criteria in RG 1.232

• PDC with minor terminology changes

• PDC with substantive technical changes

• Limitations and conditions

• Conclusions 9

Conclusions

• The NRC staff established four Limitations and Conditions (L&Cs)

• TEUSA provided a sufficient set of PDC for the IMSR design, subject to the L&Cs

• The PDC (subject to the L&Cs) establish the necessary design, fabrication, construction, testing, and performance DC for safety significant SSCs to provide reasonable assurance that the IMSR reactor could be operated without undue risk to the health and safety of the public

• The TEUSA PDC TR, Revision C, is suitable for reference in future licensing applications for the IMSR 10

Abbreviations ANSI/ANS - American National Standards Institute/American Nuclear Society CFR - Code of Federal Regulations COL - Combined license CP - Construction permit DANU - Division of Advanced Reactors and Non-power Production Facilities DC - Design criteria IMSR - Integrated Molten Salt Reactor L&C - Limitation and condition LWR - Light water reactor ML - Manufacturing license NRR - Office of Nuclear Reactor Regulation NRC - Nuclear Regulatory Commission OL - Operating license PDC - Principal design criteria RG - Regulatory guide SDA - Standard design approval SSC - Structure, system, or component SE - Safety evaluation TEUSA - Terrestrial USA, Inc.

TR - Topical report 11