ML22119A253
| ML22119A253 | |
| Person / Time | |
|---|---|
| Issue date: | 04/21/2022 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| Wang W | |
| References | |
| NRC-1938 | |
| Download: ML22119A253 (259) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards Kairos Power Subcommittee Docket Number: (n/a)
Location: teleconference Date: Thursday, April 21, 2022 Work Order No.: NRC-1938 Pages 1-197 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1716 14th Street, N.W.
Washington, D.C. 20009 (202) 234-4433
1 1
2 3
4 DISCLAIMER 5
6 7 UNITED STATES NUCLEAR REGULATORY COMMISSIONS 8 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 9
10 11 The contents of this transcript of the 12 proceeding of the United States Nuclear Regulatory 13 Commission Advisory Committee on Reactor Safeguards, 14 as reported herein, is a record of the discussions 15 recorded at the meeting.
16 17 This transcript has not been reviewed, 18 corrected, and edited, and it may contain 19 inaccuracies.
20 21 22 23 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 UNITED STATES OF AMERICA 2 NUCLEAR REGULATORY COMMISSION 3 + + + + +
4 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 5 (ACRS) 6 + + + + +
7 KAIROS POWER SUBCOMMITTEE 8 + + + + +
9 THURSDAY 10 APRIL 21, 2022 11 + + + + +
12 The Subcommittee met via Video-13 Teleconference, at 1:00 p.m. EDT, David A. Petti, 14 Chairman, presiding.
15 COMMITTEE MEMBERS:
16 DAVID A. PETTI, Chairman 17 RONALD G. BALLINGER, Member 18 VICKI M. BIER, Member 19 CHARLES H. BROWN, JR. Member 20 VESNA B. DIMITRIJEVIC, Member 21 GREGORY H. HALNON, Member 22 JOSE MARCH-LEUBA, Member 23 WALTER L. KIRCHNER, Member 24 JOY L. REMPE, Member 25 MATTHEW W. SUNSERI, Member 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 1 ACRS CONSULTANTS:
2 DENNIS BLEY 3 STEPHEN SCHULTZ 4
5 DESIGNATED FEDERAL OFFICIAL:
6 WEIDONG WANG 7
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
3 1 A-G-E-N-D-A 2 ACRS Chairman Introductory Remarks 3 Chairman . . . . . . . . . . . . . . . . . 4 4 NRC Staff Introductory Remarks 5 NRC Staff . . . . . . . . . . . . . . . . . 7 6 Design overview 7 Kairos Power . . . . . . . . . . . . . . . 14 8 Summary of Application Review 9 NRC Staff . . . . . . . . . . . . . . . . 166 10 Public Comment . . . . . . . . . . . . . . . . 196 11 Adjourn 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 1 P-R-O-C-E-E-D-I-N-G-S 2 1:00 p.m.
3 CHAIRMAN PETTI: The meeting will now come 4 to order. This is a meeting of the Kairos Power 5 Licensing Subcommittee of the Advisory Committee on 6 Reactor Safeguards. I'm David Petti, Chairman of 7 today's Subcommittee meeting.
8 ACRS members in attendance are Jose March-9 Leuba, Joy Rempe, Matt Sunseri, Walt Kirchner, Vesna 10 Dimitrijevic, Vicki Bier, and Greg Halnon.
11 Ron, are you on? Yes, I see Ron 12 Ballinger. And I haven't seen Walt Kirchner yet.
13 MEMBER BROWN: I'm here, Dave.
14 CHAIRMAN PETTI: Oh, and Charlie, you are 15 there. Okay, good.
16 MEMBER BROWN: Yes.
17 CHAIRMAN PETTI: Thank you. Steve Schultz 18 and Dennis Bley, our consultants, are also present.
19 Weidong Wang of the ACRS staff is the Designated 20 Federal Official for the meeting.
21 During today's meeting the Subcommittee 22 will get an overview of the Kairos Hermes Testing 23 Facility construction permit application and the NRC 24 staff approach to the safety review. The Subcommittee 25 will hear presentations by and hold discussions with 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 1 NRC staff, Kairos Power representatives, and other 2 interested persons regarding this matter.
3 The part of the presentations by the 4 Applicant and the NRC staff may be closed in order to 5 discuss information that is proprietary to the 6 Licensee and its contractors pursuant to 5 U.S.C.
7 552(b)(c)(4).
8 Attendance at the meeting that deals with 9 such information will be limited to the NRC staff and 10 its consultants, Kairos Power, and those individuals 11 and organizations who have entered into an appropriate 12 confidentiality agreement with them. Consequently, we 13 will need to confirm that we have only eligible 14 observers and participants in the closed part of the 15 meeting.
16 The rules for participation in all ACRS 17 meetings, including today's, were announced in the 18 Federal Register on June 13th, 2019. The ACRS section 19 of the U.S. NRC public website provides our charter, 20 bylaws, agendas, letter reports, and full transcripts 21 of all full and subcommittee meetings, including 22 slides presented there.
23 The meeting notice and agenda for the 24 meeting were posted there. We have received no 25 witness statements or requests to make an oral 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 1 statement from the public.
2 The Subcommittee will gather information, 3 analyze relevant issues and facts, and formulate 4 proposed positions and actions as appropriate for 5 deliberation by the full committee in the future.
6 A phone bridge line has been opened to 7 allow members of the public to listen in on the 8 presentations and the Committee discussion.
9 Additionally, we've made an MS Teams link available, 10 and there will be an opportunity for comment at the 11 conclusion of the prepared presentations for the 12 public that is interested in making such a comment.
13 A transcript of the meeting is being kept, 14 and it's requested that speakers identify themselves 15 and speak with sufficient clarity and volume so that 16 they can be readily heard.
17 Additionally, participants should mute 18 themselves when not speaking. To mute or unmute on a 19 phone, push Star 6. If you're on Teams and want to 20 make a public comment, you can just raise your hand 21 when we ask for public comments.
22 We'll now proceed with the meeting. And 23 I'd like to start by calling up NRR management, Duke 24 Kennedy. I understand you're going to say a few 25 words.
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 1 MR. KENNEDY: Good afternoon, everybody, 2 members of the ACRS, members of the public in 3 attendance. And I'd just like to give a few opening 4 remarks. So my name is Duke Kennedy, and I am the 5 acting chief of the Advanced Reactor Licensing Branch.
6 And it's my pleasure to be here today to provide 7 introductory remarks on behalf of the Division of 8 Advanced Reactors and Non-power Production and 9 Utilization Facilities in the Office of Nuclear 10 Reactor Regulation.
11 With me today is Mr. Ed Helvenston of the 12 Non-Power Production and Utilization Facility 13 Licensing Branch who is one of the project managers 14 for the Hermes review. And he'll provide the staff 15 presentation.
16 Also here is Jeff Schmidt of the Advanced 17 Reactor Technical Branch, who's the lead technical 18 reviewer, as well as Ms. Michelle Hart, another 19 technical reviewer, and other NRC staff who are 20 involved in the Hermes review.
21 So I'd like to thank the ACRS Subcommittee 22 for convening this meeting today to provide the staff 23 an opportunity to introduce the ACRS to the staff's 24 approach to the Hermes review.
25 So we recognize that Hermes represents the 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 1 confluence of two uncommon attributes and that it's a 2 non-light-water reactor design, and it's proposed to 3 be licensed and operated as a testing facility under 4 Section 104(c) of the Atomic Energy Act of 1954.
5 So recognizing this unique, novel 6 situation, the staff is pursuing a deliberate risk-7 informed approach to this review with a focus on 8 safety and reasonable assurance of protection of 9 public health and safety.
10 So the staff and Kairos Power have had the 11 opportunity to brief the ACRS on Kairos Power topical 12 reports. Some of these are applicable to both the 13 power reactor design and the non-power Hermes design.
14 So the staff has appreciated helpful comments from the 15 ACRS on topical reports covering different areas such 16 as reactor coolant, scaling methodology, the licensing 17 modernization project, and more recently fuel 18 qualification and mechanistic source term. So many of 19 these topical reports are or will be referenced in the 20 Hermes application.
21 So the staff looks forward to continued 22 interactions with the ACRS Subcommittee as this review 23 proceeds. Of course, we're at the initial meeting 24 here to kick things off and look forward to hearing 25 presentations from Kairos and questions and comments 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 1 from the ACRS members as well. So thank you very 2 much. I'm looking forward to an informative meeting.
3 CHAIRMAN PETTI: Thank you, Duke. Before 4 we turn it over to Kairos, just to reiterate for 5 members, we do have a closed session if we want to get 6 into more technical details, so just note that.
7 Kairos, the ball's in your court.
8 MEMBER REMPE: Dave, this is Joy.
9 CHAIRMAN PETTI: Yes?
10 MEMBER REMPE: Could I ask a question of 11 Duke before we go to Kairos?
12 CHAIRMAN PETTI: Okay.
13 MEMBER REMPE: Are you still there? Oh, 14 okay. So I've been pondering the last few weeks here 15 about what the NRC does to decide whether a facility 16 is a test reactor or a demonstration reactor. Because 17 we hear about, well, it's a lighter footprint with a 18 test reactor with respect to licensee.
19 And if I actually read, like, in Section 20 10 of the DCA, it says that the test reactor is being 21 constructed to demonstrate this new technology and 22 there aren't any special test facilities. You'll do 23 startup testing, but we do startup testing for 24 commercial reactors in some respects.
25 How does the NRC decide? And then what's 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 1 the cutoff with respect to power levels where you 2 suddenly say, no, come on guys, this is not going to 3 be a test reactor? It's a demonstration facility, and 4 you have a power level that shouldn't go through a 5 certain type of process. Are there some hard and fast 6 rules?
7 MR. KENNEDY: Well, Ed Helvenston will 8 touch on some of that in his presentation. But in 9 response to your questions, first, the term 10 demonstration reactor actually has a fairly particular 11 meaning when it comes to the Atomic Energy Act. And 12 it typically includes connection to an electrical grid 13 and demonstrating that the reactor technology can be 14 commercialized.
15 So Kairos Hermes will not be connected to 16 an electrical grid. They will not produce 17 electricity, and therefore wouldn't fall under that 18 definition of -- it's not a definition, but the 19 classification as a demonstration reactor per the 20 Atomic Energy Act. So it is a research and 21 development facility.
22 It is not a demonstration reactor, 23 although it may be used to demonstrate some of the 24 technologies or safety features. It doesn't fit under 25 those clauses in Section 202 of the Energy 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 1 Reorganization Act that talk about demonstration 2 reactors. So I think that's the answer to your first 3 question.
4 To the second question, there is a few 5 criteria that determine whether a Class 104(c) 6 research and development facility is a research 7 reactor or a testing facility. The easiest one is the 8 ten-megawatt thermal power cutoff limit. Above ten 9 megawatts, a facility is a testing facility. Below 10 ten megawatts, it would be research reactor.
11 So at or below ten megawatts it would be 12 research reactor unless it meets certain conditions 13 that are laid out in 10CFR Part 50. And those relate 14 to other features such as a liquid fuel, Kairos does 15 not have a liquid fuel, or a large cross sectional 16 area in the core that could be used for experiments.
17 And so these features would be restricted 18 to reactors with a power level of one megawatt. So if 19 these features, none of these features existed, and 20 the reactor power was greater than one megawatt, it 21 would also be classified as a testing facility.
22 So Kairos, being greater than ten 23 megawatts thermal, the Hermes reactor, it is clearly 24 a testing facility, or that's where it would fall 25 under section 104(c) of the Atomic Energy Act.
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 1 There is no actual upper bound to power 2 level in the Act or the regulations. The designation 3 of testing facility is based on the facility being 4 useful for research and development. So if it were 5 100 megawatts or 200 megawatts, it would still be 6 eligible be classified as a testing facility under the 7 Act and the regulations.
8 The next categorization would be a 9 commercial facility, and that would be dependent upon 10 the types of activities that it's carrying out. And 11 Mr. Helvenston will explain this more in his part of 12 the presentation.
13 So the answer is there is not an upper 14 bound, and the staff recognizes this, and the guidance 15 recognizes this. And so we are prepared to be able to 16 apply our review at the right level considering the 17 risks of the facility which can increase as power 18 level increases. And so we have the flexibility to 19 treat this case with the due diligence needed 20 respecting the potential risks.
21 MEMBER REMPE: Thank you. That helps a 22 lot. Have you had any experience in the past of ever 23 applying the regulation to a testing facility of this 24 magnitude? I know NRC was involved in the FFTF 25 approach, but have you ever had the responsibility to 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
13 1 license a testing facility of this power level?
2 MR. KENNEDY: Not that I'm aware of. As 3 far as I know, the National Institute of Standards and 4 Technology reactor at 20 megawatts is the closest that 5 NRC has licensed. If I'm incorrect about that, I will 6 provide that information to the Subcommittee. But to 7 the extent of my knowledge, we have not.
8 MEMBER REMPE: This helps. Thank you very 9 much.
10 MR. KENNEDY: Thank you.
11 CHAIRMAN PETTI: Okay, Kairos.
12 MR. PEBBLES: All right, thank you, Mr.
13 Chairman and members of the ACRS. My name is Drew 14 Pebbles, and I'm a licensing manager here at Kairos 15 Power.
16 As Duke mentioned, we have the opportunity 17 to engage the Subcommittee on several of our topical 18 reports that we submitted in pre-submittal phase. And 19 we look forward to engaging as you begin your review 20 of the Hermes PSAR.
21 Before we get started on the presentation, 22 I did want to provide some context for the level of 23 detail that you can expect in this presentation as 24 well as the level of detail that you can expect in the 25 PSAR that you'll begin to review.
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 1 First it's worth noting that we are 2 following the Part 50 process which is a two-step 3 process. And the construction permit application is 4 based on a preliminary design and a preliminary safety 5 analysis report.
6 Because of that, you won't see the same 7 fidelity in design or the safety case that you could 8 expect to see with the operating license application.
9 And today's overview reflects some of that level of 10 detail.
11 Second, it's worth noting that Hermes is 12 a non-power reactor. So the requirements in Part 50 13 are slightly different for non-power reactors than 14 they are for power reactors. We recently got approval 15 of our topical report with KP-TR-004, which is a 16 regulatory analysis topical in which we broke down all 17 of the requirements in Part 50 and which ones apply 18 and do not apply to the Hermes reactor.
19 And then finally, just due to the past 20 constraints of today's meeting, we won't be able to go 21 into detail in every system that you would expect to 22 see in the PSAR. But we tried to pick the major and 23 most important structure systems and components that 24 if you do have any specific questions on supporting 25 systems that you don't see in the presentation feel 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 1 free to ask.
2 Michael, are you sharing your screen?
3 MEMBER REMPE: Dave, this is Joy. I have 4 another question. I can't raise my hand very easily.
5 It was okay to ask it?
6 CHAIRMAN PETTI: Sure.
7 MEMBER REMPE: While you're getting the 8 slides up, I became aware of last week that you guys 9 had submitted some updates to your construction permit 10 where, you know, there were some substantial changes, 11 like you eliminated an intermediate cooling loop. And 12 you changed the operating number of years from ten to 13 four years.
14 Could you talk a little bit about what 15 made those substantial changes, you know, what 16 motivated you to make such changes? And should we 17 expect similar changes coming down the pike here?
18 Because, you know, we have limited time to do this 19 review.
20 And I know Applicants often complain about 21 how much it costs to go through an NRC review. And 22 when you're making that kind of change, that increases 23 costs. And so it'd be good to have some confidence 24 that we are expending our review time at the right 25 time.
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 1 MR. PEBBLES: Sure. Thank you for that 2 question. As far as the getting rid of the 3 intermediate loop, we don't think it had a materially 4 large impact on the application. We were in very 5 close contact with the NRC reviewers as we made the 6 change.
7 It turns out that there is very little 8 safety significance to that part of the plant. So 9 where it showed up in the application was actually 10 relatively minor compared to some of the other systems 11 that play a more important role in the safety case for 12 Hermes.
13 As far as the operating life, that came 14 about from the NRC review of some of the associated 15 topical reports that are currently under review with 16 the NRC. And it turned out, in the case of operating 17 life, that it could have slowed down our development 18 path which I'll talk about a little bit in the 19 introduction slide. But again, this wasn't a large 20 material change to the application.
21 CHAIRMAN PETTI: Just a follow on question 22 on the lifetime, you know, pebble beds can take a fair 23 amount of time to get to equilibrium. Is it four 24 full-power years, or four calendar years? And how 25 long, you know, relative to when you're going to get 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
17 1 to equilibrium, how much are you projecting in terms 2 of operating beyond equilibrium?
3 MEMBER MARCH-LEUBA: Somebody answering?
4 MR. PEBBLES: So it is calendar years.
5 I'm going to ask one of my subject matter experts for 6 the timing to equilibrium.
7 MR. SATVAT: It depends, it's close to a 8 year.
9 CHAIRMAN PETTI: So introduce yourself.
10 MR. SATVAT: This is Nader Satvat, manager 11 of Core Design. The residence time of Hermes reactor 12 is about close to 200 days. So if the reactor 13 operates steadily, it will get to equilibrium in about 14 a year.
15 CHAIRMAN PETTI: Yeah, but when you start 16 up, are you starting up like a traditional pebble-bed 17 where you start out with graphite pebbles and slowly 18 add lower image pebbles and then, you know, as those 19 burn, add higher image pebbles? So there's this 20 period where there's a lot of stuff going on with, 21 let's say, but not the steady state fuel element, if 22 you will.
23 MR. SATVAT: It's an area that we are 24 studying. But effectively, your assessment is 25 correct. We will adjust the effective abridgement of 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 1 the core to stay within a reasonably small excess 2 reactivity, whether using solar enriched fuel or 3 additional natural uranium to the core at the startup, 4 to bring the effective enrichment down.
5 CHAIRMAN PETTI: Okay. It's just, you 6 know, you'd like to get a -- I'm assuming you guys 7 want a fair number of pebbles to get to full burn-up 8 in the four years. That would seem to be a very good 9 goal.
10 MEMBER REMPE: So I heard answers to my 11 first two comments about the changes and that you 12 viewed them to not be significant. I didn't hear 13 about are we going to see some additional changes in 14 the construction permit, or you think it's fairly 15 stable here?
16 MR. PEEBLES: We think it's stable. There 17 may be minor changes that result from the discussions 18 with the review staff as we get through the current 19 audits that are open and any requests for additional 20 information that could come from the staff. But we 21 are not planning any major changes to the construction 22 permit application. Yes, sorry.
23 CHAIRMAN PETTI: Okay, keep going. If you 24 hear silence march forward.
25 (Laughter.)
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 1 MR. PEEBLES: Okay, next slide please.
2 All right, Kairos is a very mission-driven company, so 3 we like to start every presentation by reiterating our 4 mission which is to enable the world's transition to 5 clean energy, with the ultimate goal of dramatically 6 improving people's quality of life while protecting 7 the environment.
8 So, in order to achieve this mission, we 9 have to prioritize our efforts to focus on our clean 10 energy technology, specifically the KP-FHR, and make 11 sure that it is affordable and safe.
12 Next slide, please. So a quick look at 13 the agenda. I'll give a brief introduction to Kairos 14 and where the Hermes reactor fits in our development 15 path.
16 And then I'll turn it over to the 17 technical team to discuss the fuel and core design, 18 the reactor vessel and internals, the heat transport 19 systems, including the normal primary heat transport 20 system and the safety-related secure heat removal 21 system, as well as the pebble handling and storage 22 system.
23 Then we'll talk about some of the safety-24 related structures like the reactor building, the I&C 25 and electrical, and then we'll follow-up with an 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 1 overview of the safety case.
2 Next slide. Oh, delay, okay.
3 So a little bit about Kairos Power. Like 4 I said on the mission statement, we're singularly 5 focused on commercializing our clean energy technology 6 which is the fluoride, salt-cooled, high-temperature 7 reactor, or FHR. We were founded back in 2016, and 8 we're at a current staffing level of about 269.
9 That number is probably already out of 10 date, because we're growing every day. And it's also 11 worth noting that 90 percent of that staff is 12 engineering-focused which just underscores how 13 committed we are to achieving our mission.
14 We're privately funded, and our schedule 15 is driven by a goal to commercially demonstrate by the 16 2030s. That target date is based on when a large 17 capacity of natural gas is expected to retire. So our 18 cost targets are also in line with those natural gas 19 plants.
20 In order to meet those aggressive costs 21 and schedule goals, we've adopted a rapid iteration 22 approach to developing our technology. We use rapid 23 iteration throughout our development process, but on 24 this slide we depicted several of the major hardware 25 milestones that will occur from these iterations.
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
21 1 So if we start over on the left part of 2 the slide, you see the engineering test unit 3 demonstration experiment which is a non-nuclear water-4 based system that's up and running here in our 5 facility in Alameda.
6 Next is the engineering test unit which is 7 a non-nuclear Flibe-based system. It's a scaled down 8 version of our commercial reactor. And the scale is 9 actually very close to the Hermes reactor. It's in 10 the final stages of being completed and should be 11 operational within the next couple of months. And 12 that is located at our facility in Albuquerque.
13 We will be able to incorporate a lot of 14 that learning into the next iteration, which is our 15 first nuclear demonstration, which is the Hermes 16 reactor that I'll talk a little bit about on the next 17 slide.
18 And then following the Hermes reactor, we 19 have a full scale version of the commercial plant 20 that's non-nuclear that will be used for user training 21 and other purposes, that's our U-facility, and then 22 finally, the first commercial plant.
23 Next slide.
24 MEMBER REMPE: This is Joy. I had a 25 question or a comment on the past slide. When you go 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 1 from the 35 megawatts thermal up to the 100 and, well, 2 when you go up from the Hermes reactor to the 140 3 megawatt electric plant, how do you know that the 4 Hermes is going to be of sufficient scale that you'll 5 have confidence in the commercial plant?
6 I mean, we've got a long history in the 7 US, as well as Germany when they went from AVR to 8 THTR. We went from Peach Bottom to the Fort St. Vrain 9 reactor. And scale up led to problems that the larger 10 plants weren't commercially viable. What gives you 11 confidence you've captured enough of the salient 12 features in the Hermes that your scale-up's going to 13 work?
14 MR. HAUGH: Thanks, Joy, this is Brandon 15 Haugh, Director of Modeling and Simulation.
16 Classically when you look at the LWR fleet especially, 17 I think you picked some that were, you know, gas 18 reactor types that have their own challenges.
19 You know, this type of scale above 10-X is 20 very common. They went from very small, to medium, to 21 large. And large is very large. We're not making 22 those kind of leaps. So we figured this 10-X step is 23 very reasonable compared to previous technologies.
24 And also the safety features, and 25 behaviors, and systems are pretty much identical at 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 1 the Hermes reactor which has some small changes in 2 scale. Particularly around safety systems and safety 3 features, they're nearly identical. So that's the 4 reason we think that step is not too big, and it 5 doesn't present any undue risk.
6 MEMBER REMPE: You're telling me you think 7 that the molten salt reactor is more similar to a 8 light-water reactor than a non-LWR type of scale-up, 9 huh?
10 MR. HAUGH: No, I'm not saying that, I'm 11 just saying there is precedents. And in the 12 confidence in our technology, we believe that's a 13 reasonable step.
14 MEMBER REMPE: And that confidence comes 15 from the molten salt reactor experiment at Oak Ridge 16 or --
17 MR. HAUGH: It comes from a combination of 18 all the technology development activities we're doing, 19 and the safety case we're presenting, along with our 20 whole reactor program.
21 MEMBER REMPE: Thank you.
22 MR. HAUGH: Thanks.
23 CHAIRMAN PETTI: Just a quick 24 clarification that the U-facility will be the same 25 power as the commercial?
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 1 MR. HAUGH: The U-facility is an 2 electrically heated facility to demonstrate the full 3 scale primary system and to help with training on 4 operators and maintenance. So the electrical power 5 level is not determined yet, because it won't be 6 there. It's not to produce power, and it's --
7 CHAIRMAN PETTI: Right. But thermally, in 8 terms of heat fluxes, you're going to try to match, 9 you know, those sorts of things?
10 MR. HAUGH: We haven't determined that 11 yet. Because it's not necessarily a facility that 12 tests in terms of safety and things. It's more to 13 demonstrate the physical capability to manufacture it 14 and also to train people to work on the full scale 15 equipment.
16 CHAIRMAN PETTI: Okay. So it could be a 17 step between the 35 megawatt Hermes and the 18 commercial?
19 MR. HAUGH: Yes. I would very much expect 20 that the electrical load we put in to heat the U-21 facility is much smaller than a commercial and nuclear 22 heat load we would have in the KPX reactor.
23 CHAIRMAN PETTI: Okay. Thanks.
24 MEMBER REMPE: And the --
25 CHAIRMAN PETTI: That was Brandon Haugh, 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 1 the director of Modeling and Simulation.
2 MEMBER REMPE: And, Brandon, I guess I 3 just have one final comment, I think, about the steam 4 generators at San Onofre when you talk about the 5 confidence in scale-up with the light-water reactor 6 industry.
7 MR. HAUGH: Well, there's a whole other 8 set of reports on what went wrong there. And that has 9 nothing to do --- well, it had something to do with 10 the scale-up, but a lot of other things, I don't 11 think, are comparable.
12 This is Brandon Haugh again, I used to 13 work there, so --
14 MEMBER REMPE: I know.
15 MR. PEEBLES: All right, so on this slide, 16 just a little more about Hermes. The figure on the 17 right gives you an idea of scale between both the non-18 nuclear ETU, and the nuclear Hermes, and the non-19 nuclear U-facility and KPX.
20 So what are we trying to demonstrate with 21 this reactor? First and foremost, cost, establishing 22 a competitive cost through our iterative learning 23 cycle, which is part of a deliberate and incremental 24 risk reduction of the design and testing iteration 25 loops.
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 1 We're also flexing the supply chain which 2 also has an effect on cost, but making sure that we're 3 advancing the supply chains for specialized KP-FHR 4 components and materials. The licensing approach, 5 although the non-power reactor licensing approach will 6 be slightly different, licensing certain safety 7 concepts with Hermes will help inform the licensing 8 process for the KPX reactor.
9 And then finally, operations, providing a 10 complete demonstration of nuclear functions, including 11 reactor physics, fuel, structural materials, 12 irradiation, an radiological controls.
13 MEMBER REMPE: This is Joy ---
14 CHAIRMAN PETTI: So just a ---
15 MEMBER REMPE: Oh, go ahead Dave.
16 CHAIRMAN PETTI: Just, I would imagine, 17 you don't actually say it on the slide, but I would 18 imagine that any sort of specifications and procedures 19 that are used for Hermes will certainly inform what 20 needs to be done in the power reactor, so that it 21 provides basically a knowledge base so that you have 22 confidence that your procedures are sort of the right 23 ones. You're starting, you know, up the learning 24 curve, if you will.
25 MR. PEEBLES: Absolutely. And that's a 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 1 great example of where the iterative learning approach 2 come into play.
3 CHAIRMAN PETTI: Right.
4 MEMBER REMPE: So, Dave, I had question I 5 wanted to ask. So I ran something through the CP 6 application. I didn't see anything about your plan.
7 I don't know if you call it a capacity or availability 8 for the Hermes reactor. Do you have any idea how much 9 you're going to run it with respect to available time?
10 Are you planning to run it once a week or, you know, 11 an hour a week. Or have you guys thought about that 12 very much yet?
13 MR. PEEBLES: No, we don't have that 14 detail at this time.
15 MEMBER REMPE: Because I think that would 16 be important if you're going to demonstrate how, you 17 know, again I'm thinking about what happened with Fort 18 St. Vrain and availability to have it operating a lot.
19 MR. PEEBLES: Right, appreciate the 20 comment.
21 MR. PEEBLES: All right, so next I'm going 22 to turn it over to Brandon Haugh, the senior director 23 of Modeling and Simulation.
24 MR. HAUGH: Hi, thanks. This is Brandon 25 Haugh again. I'm going to introduce the first slide 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 1 here where we just introduce the fuel form, and then 2 I'll turn it over to the manager of Core Design, Nader 3 Satvat, to go into a little bit more detail on the 4 design of the core and tools.
5 So as some of us have seen before, we're 6 using a pebble fuel form. This pebble fuel form has 7 three regions. It's got a lower density graphite in 8 the center of it, that's to maintain the buoyancy of 9 the fuel in the side coolant. It's got a fuel region 10 that's on the outside of that low dense region, and 11 then it's got an outer fuel-free shell designed to 12 protect the fuel region and prevent salt ingress.
13 That fuel region contains particles that 14 are based on the AGR program for qualification, very 15 similar specifications. For sizing, you can see on 16 this slide that that pebble is roughly the size of a 17 ping pong ball, about four centimeters in diameter.
18 Core design then is a pebble-backed 19 concept where the pebbles circulate from the bottom to 20 the top of the core, since they're buoyant in Flibe.
21 And then that core consists of a mixture of graphite 22 moderator pebbles and fuel pebbles for optimum 23 moderation.
24 MR. SATVAT: This is Nader Satvat, manager 25 of Core Design. The specifics of the design of the 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 1 core of Hermes are listed in the table on Slide 10.
2 The power of the reactor is 35 megawatts thermal. The 3 fuel cycle of the core is 190 days average residence 4 time, about four to six passes. This is not fully 5 determined, but that's the range of pass for a pebble.
6 The discharge burn-up of the reactor is 7 six to eight percent FIMA. The safety parameters of 8 the core, overall negative temperature reactivity 9 coefficients, and also negative fuel and moderator 10 temperature reactivity coefficients, also the void and 11 coolant temperature coefficients are negative.
12 The methods were calculations for using 13 high fidelity methods, such as Monte Carlo, and also 14 internally developed tool, KPACS, for sharpening of 15 the core. There is a slide about methodology here in 16 a few slides. I'll touch in this a little bit with 17 more detail.
18 (Simultaneous speaking.)
19 MR. SATVAT: The power per pebble --
20 MR. HAUGH: Is there a question?
21 CHAIRMAN PETTI: I said yeah, I had a 22 quick question. Enrichment, are you going up to the 23 LEU limit even though the burn-up's only six to eight 24 percent?
25 MR. SATVAT: We're using the upper limit 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 1 of HELU.
2 CHAIRMAN PETTI: Yes, okay. So it's 3 relatively over-enriched relative to burn-up?
4 MR. SATVAT: Yes.
5 CHAIRMAN PETTI: Yes, I got you. Thanks.
6 MR. HAUGH: Thank you.
7 MR. SATVAT: The power per pebble is about 8 1,000 watt per pebble. That is to say within the 9 qualification limit of TRISO. The pebble figure 10 factor in this core is approximately two. The coolant 11 is Flibe, enriched with Lithium-7. And the level of 12 impurity in the Flibe is also a parameter that needs 13 to be adjusted, in part, to heavy metal at a ratio to 14 get the desired temperature reactivity coefficient for 15 Flibe.
16 MEMBER MARCH-LEUBA: Yes, this is Jose 17 March-Leuba. Obviously the Hermes core is tenth of 18 the volume of the real reactor. How do you get to 19 critical? What parameters do you change to obtain 20 criticality?
21 MR. SATVAT: Thank you for the question.
22 There are two approaches that we're considering. One 23 of them is similar to how HDR10 went to criticality.
24 So we call that a layered approach. So slowly 25 inserting -- so the core at the beginning is filled 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
31 1 with graphite pebbles and slowly inserted fuel and 2 graphite with a desired ratio until we get to a 3 critical weight (phonetic). So that's one approach.
4 The other approach is called mixed 5 approach. And step by step, we are going to increase 6 the ratio of fuel to graphite and natural uranium 7 pebbles until we get to criticality.
8 In both approaches, the prediction of next 9 step is very similar to how all conventional reactors 10 are done with one-over-M approach to get there safely.
11 MEMBER MARCH-LEUBA: But doing some 12 correcting, are you planning to change the 13 configuration of the core, that you run into graphite 14 dramatic concentrations?
15 (Simultaneous speaking.)
16 MR. SATVAT: -- ratio of the pebbles, yes.
17 MEMBER MARCH-LEUBA: So if you are going 18 to do it experimentally with one of them, it's going 19 to take you a couple of years to do the startup.
20 MR. SATVAT: The layered approach is not 21 going to be time consuming as opposed to the mixed bed 22 approach. Currently PHSS is capable to re-circulate 23 the whole core in less than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. And currently 24 the calculations we have done, it takes about six to 25 ten steps to get to criticality.
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 1 So you are correct. The mix of that is 2 going to be taking time. But it also allows us to do 3 some tests on the way they're specifically checking on 4 the condition of the fuel as they circulate through 5 the core.
6 MEMBER MARCH-LEUBA: How fast can you re-7 circulate the whole core? I'm concerned about the 8 homogeny to your core, that you start filling it up 9 from the bottom, and you risk criticality. And now 10 you still have a non-critical pump that you are going 11 to go super critical when you put more. You see what 12 I mean? You have to swap it and make it homogeneous.
13 MR. SATVAT: That is a very good point.
14 At each step of the mixed bed approach, the whole 15 control rod system is fully inserted. So the 16 prediction for next step, the next step starts with 17 all the rods in and slowly withdraw. The predictions 18 are calculated based on fully withdrawn control 19 system. So if in any case that next step we're 20 mismatching and additional, extra pebbles, the 21 control reactivity will basically compensate that.
22 As far as answering your question for 23 PHSS, I'll hand it over to Nico to respond to that 24 question.
25 MR. ZWEIBAUM: Yes. Well, so hi, this is 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 1 Nico Zweibaum. I'm the director or Salt Systems 2 Design which encompasses the pebble handling and 3 storage system.
4 But as Nader was just mentioning, we are 5 currently dimensioning the pebble re-circulation 6 system to be able to re-circulate the full core in 7 about 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. These parameters may be adjusted 8 based on what comes out of core design optimization 9 and alterations, but the reality is that the hardware 10 is pretty flexible to adapt to what the needs might be 11 on the core physics side.
12 MEMBER MARCH-LEUBA: Yes. And I'm sure 13 you've thought about this. And I certainly would like 14 to see all the details. But when you do the re-15 circulation, do you remove uranium pellets and replace 16 it with a carbon pellet? Or how do you ensure 17 homogeneity if you are doing it on the fly? I'm sure 18 you thought about it, but I want to see the details.
19 MR. SATVAT: Sure. As far as the 20 mechanical design, you'll see an animation that will 21 give you a better sense of how we are sorting pebbles, 22 and extracting them, and reinserting them. And then 23 we may follow-up with more specifics after that.
24 MEMBER MARCH-LEUBA: Right. And the other 25 thing is will you use the Hermes reactor, which a 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
34 1 fantastic thing that we're doing it, to calculate all 2 those relativity coefficients. But there will be --
3 how do you measure on, you run into carbon ratio that 4 is different than in the real reactor. So we'll have 5 to extrapolate, based on calculations, to what 140 6 megawatt electric will do, right?
7 MR. ZWEIBAUM: Yes, that's correct.
8 MEMBER MARCH-LEUBA: Okay. Thank you.
9 MEMBER REMPE: I have a question about 10 your rods that are in the core that are designed to go 11 in the core. As I recall, the THTR had some damaged 12 pebbles from that. And why are you sure you're not 13 going to have the same problem? Because actually that 14 led to some unavailability with the THTR.
15 MR. SATVAT: This is Nader Satvat, manager 16 of Core Design. I'm going to hand it to Chad Nixon, 17 the responsible engineer for the testing around that 18 component.
19 MR. NIXON: Hi, this is Chad Nixon. We've 20 done testing already with shutdown elements. And one 21 of the main things here is that the elements are 22 inserting into a bed that the pebbles are positively 23 buoyant. There's much less force required to insert 24 into our pebble bed since the pebbles can't depress 25 down into the core at the point the elements are 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
35 1 inserted.
2 MEMBER REMPE: That's good. And the, 3 quote, pebbles in your test were actually the same 4 material that will be in the core.
5 MR. NIXON: The preliminary testing we've 6 done is scaled testing with plastic polypropylene 7 pebbles.
8 MEMBER REMPE: They are floating in some 9 sort of fluid, I guess?
10 MR. NIXON: In water, yes.
11 MEMBER REMPE: Is some write-up about that 12 available for us to see? Again, I only looked at the 13 CP and a couple of the topical reports. Because I 14 didn't see anything about we've done testing, and we 15 have confidence that this is going to be okay.
16 MR. NIXON: No, we're not including that 17 as part of the construction permit application.
18 MEMBER REMPE: Okay, thank you.
19 MEMBER MARCH-LEUBA: Well, I'm reading 20 ahead, and I read this slide. And I'm looking at the 21 Slide 11. The shutdown margin we're shooting for is 22 k-effective of .99, which I assume is a non-23 proprietary number. I realize this is with one full 24 rollout. But that's only two rollouts from critical.
25 We will not make any mistakes while we're rolling all 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 1 those graphite pellets. And it doesn't sound like too 2 much margin to me. But, just a comment.
3 MR. SATVAT: This is Nader Satvat. Thank 4 you, Dr. Jose March-Leuba. That's a very good point 5 that you're bringing up. If you look at our 6 application, there is a lot of margin in our control 7 system. That is just the bare minimum. But, on top 8 of that, we're actually recognizing it's first-of-a-9 kind reactor, we do have, I believe, about 4,500 PCM 10 extra margin in our control rod system.
11 MEMBER MARCH-LEUBA: So then those 4,000 12 PPM is control rod systems you don't credit, but 13 exists.
14 MR. SATVAT: It does exist, precisely.
15 MEMBER MARCH-LEUBA: Okay, thank you.
16 MR. SATVAT: Yes. And just to add one 17 more point to previous question, in this reactor, the 18 fusion length is about to eight to ten diameter.
19 There's some level of biasing in the bed, not complete 20 homogeneity. It's not going to change parameters in 21 the core. However, recognizing that mixing the bed 22 during operation is a parameter that we need to take 23 into account, we do have an uncertainty analysis 24 which looks into perturbing or biasing carbon to have 25 a metal atom ratio across the core and observing the 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 1 impact on safety parameters.
2 Now I'm going to go to Slide 11. The 3 other reactivity control and shutdown system is, as 4 demonstrated on the right picture, has three shutdown 5 elements going directly to the bed, and four 6 reactivity control systems in the reflector. For that 7 to run, the director of reactor systems will go into 8 more detail about the release mechanisms and the 9 diversity right after this session.
10 The shutdown margin compensates power 11 defect, xenon decay, operational excess reactivity, 12 and depletion of the rods. As was just discussed, the 13 shutdown margin takes into account a single most 14 reactive rod failure and 1,000 PCM to k.1.
15 The sources of operational excess 16 reactivity, core composition is one of them. And it's 17 determined for different core states to compensate 18 change, for changing power levels, or manage other 19 transients. The method, we do have a high validity 20 method to calculate the power defect which combines 21 Monte Carlo and Kairos media using Star-CCM as the 22 tool.
23 Other notes. Drive mechanism sets limit 24 on withdrawal rate, which is the rate of insertion of 25 reactivity. And, also, KP-FHR has a strong prompt 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 1 effect to reduce regular use of the RCS.
2 The next slide is the core design 3 methodology. There are three boxes here. The box on 4 the left, which is the green box, light green is the 5 safety tools. And as discussed earlier, due to lack 6 of operational data for FHRs, pebble bed FHRs, we are 7 relying on high fidelity methods, SERPENT as other 8 Monte Carlo engine reactor physics calculations, and 9 Star CCM for our pedal. The core, core is media 10 approximation.
11 Also Star-CCM is used for discrete element 12 modeling which determines the flow of pebbles in the 13 core and their distribution of resident's time which 14 is an input to KPAX. KPAX is an internally developed 15 tool to do field cycle analysis for pebble, but very 16 similar to VSOP but higher fidelity. KPATH is another 17 internally developed tool which connects a couple, 18 SERPENT and Star-CCM.
19 We do generate -- we do process of our own 20 ACE (phonetic) libraries for input to AXIOM, PSAB, and 21 SERPENT. That process is a part of our software 22 quality domain.
23 We also do have a light red box called 24 Support Tools. They're not used in our safety 25 analysis domain, but they are used for design purposes 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 1 or understanding the transient behavior of the 2 reactor. And KP-AGREE is a familiar code to threat 3 advanced gas for reactor evaluation. The KP version 4 of that is for Flibe system which is a time-dependent, 5 thermal-hydraulic, and kinetics tool couple.
6 And the next slide, there are some 7 representative information about the behavior of the 8 core with steady state data. Just for some 9 understanding of these numbers in Hermes' core, on the 10 left side we do have thermal plugs and ASP plugs. As 11 it can be seen, the thermal plugs peak in the 12 reflector, the reflector agent. At the middle there 13 are two temperatures for Flibe, and also the surface 14 temperature, and the distribution of that.
15 And on the right side is the power 16 distribution in the core, power density distribution 17 in the core, and also in the de-fueling region above 18 the core. And with that --
19 CHAIRMAN PETTI: I just have a question, 20 given the small size of Hermes, I assume it's 21 relatively leaky in terms of, you know, neutrons are 22 outside the vessel. Is that --
23 MR. SATVAT: Yes, precisely. That's 24 accurate.
25 CHAIRMAN PETTI: Yes. So the shielding is 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
40 1 going to have to take care of that.
2 MR. SATVAT: That kind of hits, that's a 3 correct point. In the -- Hermes says design, 4 reflector does a relatively good job for reducing 5 that, but still, you're right, we're taking that into 6 account for sure.
7 CHAIRMAN PETTI: Okay. So before we move 8 on to Oded, I just wanted to point out that we're 9 slightly behind schedule on our planned time allotment 10 for each slide presentation. So I just wanted to 11 check with Weidong and make sure that's that okay if 12 we start eating into the closed session time, maybe 13 take some of that back.
14 MR. WANG: I think up to Dave. Dave, how 15 do you think?
16 CHAIRMAN PETTI: No, let's just keep 17 going. Okay, Obed?
18 MEMBER MARCH-LEUBA: Yes, the time -- this 19 is Jose. The time estrangement is always the fault 20 of the members, and you can blame us for that. Keep 21 going.
22 (Laughter.)
23 CHAIRMAN PETTI: Got it.
24 MR. DORON: Okay, can you hear me okay?
25 CHAIRMAN PETTI: Yes.
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 1 MR. DORON: Okay. I'm Oded Doron, 2 Director of Reactor System Design. I'll be mainly 3 focusing today on high level overview of the vessel 4 internals and reactivity control and shutdown system.
5 Again, the content here is relatively high level.
6 We've tried to pull things directly from the PSAR 7 whenever possible so just give you a summary.
8 So a simple diagram here where you can see 9 on the left a vessel, lower head, coolant inlet 10 nozzles, and the vessel top head. Onto the right we 11 get into the internals.
12 The core structure is formed by graphite 13 blocks. Starting at the bottom we have a reflector 14 support structure that initially the reflector blocks 15 will sit on until the Flibe enters the system.
16 And then the blocks will -- they're 17 buoyant, so they will float, fueling chute, lower 18 fueling chute, the active core region, graphite 19 reflector, the core barrel which is concentric with 20 the vessel, downcomer region which is formed between 21 the core barrel and the vessel, upper plenum regions, 22 the fueling chute, and the flow diode which is 23 utilized for a natural circulation shutdown event.
24 CHAIRMAN PETTI: Just a question. Go 25 back. You probably may not be there, but you probably 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 1 know, pebble beds, the stress on the support plate, 2 you've got a lot of the pebbles to come through. You 3 have less graphite there. Have you guys gotten to the 4 stress analysis stage to see that you don't have any 5 problems exceeding limits on the support plate?
6 MR. DORON: Yes. So the support plate 7 will only --- we have to hold the weight of the 8 graphite structure until the Flibe enters the system, 9 and then the Flibe will float. And so the support 10 plate will be essentially stress free, the lower head 11 in general. It will have to support the weight of the 12 Flibe but not of the pebbles or the graphite. You'll 13 have to remember that they're buoyant.
14 CHAIRMAN PETTI: Yes, okay.
15 MR. DORON: Okay. And the weight of the 16 pebbles that are inserted, I think Nico will be 17 touching a little bit on that earlier. But they do 18 not go through that support plate. And yes, we have 19 started conducting stress analysis on the graphite.
20 CHAIRMAN PETTI: Okay. Thanks.
21 MEMBER REMPE: How big is -- what was the 22 diameter and height of the vessel? I didn't see it in 23 the PSAR.
24 MR. DORON: I don't believe it was 25 provided.
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 1 MEMBER REMPE: It doesn't have to be 2 exactly. I mean, is it three feet or --
3 MR. DORON: Eight-ish feet in diameter, 4 you know, let's say 12 to 16 in height, something like 5 that.
6 MEMBER REMPE: Thanks.
7 MR. DORON: Yes.
8 MEMBER BROWN: Can you stay on that? This 9 is Charlie Brown. I'm now back to the Slide 15 again.
10 I don't understand pebble bed reactors. You've gone 11 through this before, and I think I've forgotten. All 12 of the pebbles are inside the thing you called the 13 active core. They come up from the bottom, they go 14 out the top. Is that correct?
15 MR. DORON: Yes, sir. That is correct.
16 MEMBER BROWN: And the cooling means the 17 Flibe, is that outside, or does that get mixed with 18 the pebbles as well?
19 MR. DORON: The Flibe is everywhere.
20 MEMBER BROWN: So it's within the vessel 21 as well as external to the vessel?
22 MR. DORON: Not outside of the vessel, no.
23 Inside the vessel, within the vessel structure.
24 MEMBER BROWN: Well, you said the graphite 25 reflector is outside the vessel --
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 1 MR. DORON: Right.
2 MEMBER BROWN: -- and when the Flibe comes 3 in, that the graphite floats.
4 MR. DORON: If I said that, I misspoke.
5 So let me say it a little different maybe. The 6 graphite is in the vessel. Initially when we load, we 7 load without Flibe. We load dry.
8 MEMBER BROWN: Well, hold it. Maybe I'm 9 calling the vessel the wrong thing.
10 MR. DORON: Okay.
11 MEMBER BROWN: I'm talking about that 12 little tube in the center.
13 MR. DORON: Oh. No, sir. That is the 14 core region that is formed by the graphite structure.
15 So you have a lower plenum or fuel chute and then 16 upper plenum and de-fueling chute.
17 MEMBER BROWN: Oh, okay. So it's not like 18 there's a container that the pebbles sit in. They --
19 MR. DORON: No.
20 MEMBER BROWN: -- come up through an 21 annulus within the graphite reflector.
22 MEMBER MARCH-LEUBA: Charlie, this is 23 Jose. Maybe you can show us the Slide 16, show us the 24 flow of the coolant.
25 MR. DORON: Yes, that can help.
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 1 MEMBER MARCH-LEUBA: And we'll understand 2 better.
3 MR. DORON: Yes.
4 MEMBER BROWN: See, I looked at that one 5 to see if I could --- I'm sorry, I looked at that one.
6 I was lost there too, so I apologize. Go ahead to 16 7 if that'll help.
8 MR. DORON: That might help. And let me, 9 yes, so let me make a comment here and maybe this 10 comment will help you, make it a little clearer, is 11 that the internal structure is formed by the graphite 12 structure, okay.
13 MEMBER BROWN: Okay, but this little 14 barrel in the middle --
15 MR. DORON: That is formed by the 16 graphite.
17 MEMBER BROWN: Okay. And that's where the 18 pebbles are contained as they flow in --
19 MR. DORON: Correct.
20 MEMBER BROWN: -- and then up through.
21 And that's the blue stuff in the left-hand side? Or 22 is that the coolant flow path?
23 MR. DORON: That is the coolant flow.
24 This is all coolant here. This is not pebbles.
25 MEMBER BROWN: Okay. But the pebbles and 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 1 coolant mix, right?
2 MR. DORON: Yes. So again, Nico will 3 touch on that later in his presentation. So we have 4 pebble insertion lines. And so pebbles are inserted 5 through, and essentially through the graphite 6 structure, if you could think of it like that. And 7 then they enter through the lower fueling region. And 8 they float their merry way up through the core.
9 MEMBER BROWN: Does the graphite or the 10 Flibe go out along with the pebbles?
11 MR. DORON: The Flibe out of the free 12 surface at the top, at the top of the vessel.
13 MEMBER BROWN: So somehow the Flibe and 14 the pebbles get separated?
15 MR. DORON: Correct. Nico will go into 16 that.
17 MEMBER BROWN: Okay, all right. I'll stop 18 then. I won't slow this process down.
19 MR. DORON: Okay.
20 MEMBER BROWN: I'm sorry, I just don't 21 know pebble bed reactors.
22 MR. DORON: These are good questions.
23 These are good questions.
24 MEMBER REMPE: This is Joy. And I am 25 thinking about what I saw in the PSAR about the vessel 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 1 being fabricated and tested to have an extremely low 2 probability of leakage. And of course, I know you're 3 only talking the portion the vessel that holds the 4 coolant. Because I know you want to keep the coolant 5 above the core to make sure that it provides a fission 6 product release barrier. And I'm curious if you have 7 a specification for what an allowable leakage is.
8 Because everything leaks a little bit in life, it 9 seems like.
10 And secondly, how much above the core is 11 -- I never saw something like would give me an idea 12 whether it has to be an inch above the core, a 13 millimeter above the core, or a foot above the core.
14 Can you give me an idea of what you guys are thinking 15 about? Because I, again, didn't see it in the PSAR.
16 MR. DORON: Yes. Let me take those one a 17 time. So first of all, we are not assuming that the 18 vessel will leak Flibe. That is not an assumption 19 we're going with. So --
20 MEMBER REMPE: That's zero leakage, they 21 can't have any sort of leakage at all.
22 MR. DORON: I mean, if you think of it as 23 a -- it is the vessel that is containing the, you 24 know, all of the structure and all of the Flibe. And 25 so if I were to have leakage, it would be some kind of 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 1 a failure. It's not, I mean ---
2 (Simultaneous speaking.)
3 MEMBER REMPE: Let me interrupt you and 4 put it in a different way. I used to do leak testing 5 on sensors. And so even when we did leak testing, 6 there was a little bit of leakage. And that was 7 considered acceptable. And you're saying you're going 8 to have a perfect system that just isn't going to leak 9 at all.
10 MR. PEBBLES: So this is Drew Pebbles 11 again. That is correct, that there is no leakage 12 that's going to be allowed from the vessel. And all 13 the penetrations are above the free surface of the 14 Flibe.
15 MEMBER SUNSERI: I would add that's not 16 unlike a PWR that has zero pressure boundary leakage 17 as a criterion. And if you do get a leak, you have to 18 shut down.
19 MEMBER REMPE: When we used to do it, it 20 was like something like ten to the minus ten or 21 something --
22 MEMBER SUNSERI: No, I know, but there's 23 controlled leakage, there's pressure boundary leakage.
24 MEMBER REMPE: Having the penetrations 25 above helps, I can get that, and your wielding below.
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
49 1 So I get that. But go ahead and answer the other 2 questions, please, about how much above the core.
3 MR. DORON: I'm not sure if we defined 4 that in the PSAR, whether or not, but the fuel will 5 remain covered. So the coolant cannot drain lower 6 than covering the fuel.
7 MEMBER REMPE: Okay. So I think that's 8 going to be important to understand, because you're 9 going to have to have instrumentation to understand 10 when to get worried about that it's getting too close 11 to the top of the core. And I'm guessing you don't 12 want it just right level with the core.
13 But it'll be interesting as we evaluate 14 the instrumentation to make sure that there is enough 15 above the core that the sensors give signals to the 16 operators saying we've got a problem, and we need to 17 do something.
18 MR. DORON: Yes. And when Anthony, our 19 director of Instrumentation, Control and Electrical 20 speaks later, maybe he could touch on that just a 21 little bit. But you're correct.
22 CHAIRMAN PETTI: So but just to ask the 23 question a slightly different way, how far from the 24 top plate is the Flibe level?
25 MR. DORON: I don't believe we define that 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 1 --
2 CHAIRMAN PETTI: Okay.
3 MR. DORON: -- in the PSAR either. But, 4 I mean, you know, you could throw a number out. I 5 mean, some several inches, something like that if you 6 like it, during normal operations.
7 CHAIRMAN PETTI: Yes. Only if you want to 8 stay below those penetrations, you know, you've been, 9 yes. Okay.
10 MR. DORON: Correct. Good questions.
11 Okay. Let me jump into the flow here, okay. So if 12 you look on the left, normal operation coolant flow 13 path, I have the flow entering through the inlet 14 nozzles. And you'll recall I mentioned that the core 15 barrel is concentric with the vessel and the gap 16 between the core barrel and the vessel forms our 17 downcomer.
18 So I have a cold inlet coming through the 19 nozzle, through the downcomer, all the way down, 20 coming around and up through the core region that's 21 formed by the graphite, up through the upper plenum 22 and out the top.
23 So during natural circulation, I have 24 similar flow path, except I don't have my pump 25 anymore. And so it's not coming through the inlet, 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 1 and it's not coming out the top.
2 Instead I have the flow coming naturally 3 up through the core, heating up and then making its 4 way through the flow diode, and then into the 5 downcomer region where the heat is pulled out with our 6 DHRS, or decay heat removal system which is on the 7 outside of the vessel. And Nico will touch on that 8 later. It cools down through the downcomer, and then 9 repeats the process.
10 MEMBER MARCH-LEUBA: So let me see if I 11 understand. This is Jose. On the left, see on the 12 left when you're pumping, when you have a flow diode, 13 the red coolant goes out of the vessel to the DHRS, 14 correct, and then comes back? I don't see a red arrow 15 coming out.
16 MR. DORON: Right. So the DHRS does not 17 take the actual coolant. The DHRS removes the heat 18 from the vessel wall.
19 MEMBER MARCH-LEUBA: That is for natural 20 circulation.
21 MR. DORON: Yes.
22 MEMBER MARCH-LEUBA: I said the inside as 23 decay heat. I meant the normal operation of --
24 MR. DORON: Normal operation, the PHTS, 25 yes, the coolant comes out the top, out of the top 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 1 around and back through the inlet.
2 MEMBER MARCH-LEUBA: Okay. That's ---
3 MEMBER BROWN: And so going back, it's 4 only back pressure from the inlet that keeps the hot 5 stuff from going out through the diode.
6 MR. DORON: Yes, sir, that's correct.
7 MEMBER BROWN: In the left-hand one.
8 MR. DORON: Correct.
9 MEMBER BROWN: And is there something up 10 at the top where the red arrows, the red stuff goes 11 out through one of the pipes up at the top?
12 MR. DORON: Yes, there's a pump. But 13 we're not showing the pump here in this diagram --
14 MEMBER BROWN: Oh, okay. And then it goes 15 back, it goes around and gets cooled?
16 MR. DORON: Correct.
17 MEMBER BROWN: Is that Flibe only, or is 18 that -- are there pebbles mixed in with that as well?
19 MR. DORON: Flibe only, hopefully. Yes, 20 Flibe only.
21 MEMBER BROWN: So even though the Flibe 22 and the pebbles are mixed down in the core region --
23 MR. DORON: Correct.
24 MEMBER BROWN: They just --
25 MR. DORON: They cannot enter the hot 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
53 1 plenum.
2 MEMBER BROWN: That little triangle at the 3 top?
4 MR. DORON: Okay, so let's go back a 5 slide, Drew.
6 MEMBER BROWN: How does he get separated?
7 MR. DORON: So do you see where it says 8 upper plenum there?
9 MEMBER BROWN: Yes.
10 MR. DORON: Yes, so flow makes it into the 11 upper plenum, but pebbles do not. So graphite is 12 extremely machinable, extremely machinable. We can 13 make almost any shape to our heart's content within 14 reason, obviously. But we have it designed in such a 15 way that flow enters the upper plenum, but pebbles do 16 not.
17 MEMBER BROWN: Is it based on physical 18 size?
19 MR. DORON: Correct.
20 MEMBER BROWN: And, oh, geez. Okay.
21 MEMBER MARCH-LEUBA: So can I say that 22 this reactor is going to be 3D printed?
23 (Laughter.)
24 MR. DORON: You could say that, but it's 25 not going to be, no. It going to be --
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
54 1 MEMBER MARCH-LEUBA: Three-D hulls.
2 (Simultaneous speaking.)
3 MR. DORON: I mean, it's worthwhile to say 4 that, you know, we're machining a full graphite 5 structure currently for our engineering test unit 6 that, you know, drew had in his model there. So this 7 is not conjecture here. We're actually doing this.
8 And what I will tell you here is that --
9 and if there's more I think I'd prefer to take it to 10 the closed session. The graphite is extremely 11 machinable, very, very machinable to very, very high 12 tolerances.
13 MEMBER BROWN: But how does the Flibe and 14 the pebbles get differentiated? I mean, is there 15 something --
16 MR. DORON: The pebbles can't --- there's 17 coolant paths that restrict flow, that don't allow 18 pebbles into there.
19 MEMBER BROWN: But the pebbles can't block 20 it?
21 MR. DORON: Well, correct. Because the 22 pebbles are continuously moving.
23 MEMBER BROWN: Well, so is the Flibe.
24 MR. DORON: So is the Flibe.
25 (Laughter.)
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
55 1 MR. DORON: Yes. Yes, sir. Yes. Again, 2 I think -- I'm hopeful, maybe we can circle back after 3 Nico's presentation when you see a little bit --
4 MEMBER BROWN: All right.
5 MR. DORON: Let's circle back after that 6 and see if this, in combination with his presentation, 7 help answer, help shed some light on your questions.
8 MEMBER BROWN: Okay.
9 DR. BLEY: This is Dennis Bley. Is there 10 any chance, for the closed session, you guys have some 11 movies that would let people understand this better?
12 MR. DORON: I'll leave that to Drew. We 13 have some PHSS movies that we've done. I don't know 14 --
15 MR. PEBBLES: Yes, we have some animation 16 for the PHSS presentation. So we can circle back 17 after that and see if it helps clear up some ---
18 MR. DORON: Yes.
19 MR. PEBBLES: We don't have any backup 20 slides though, only what we submitted on the topic.
21 MR. DORON: Okay, shall we continue? All 22 right. This is the head layout. So, I mean, I can go 23 through every one or not here. But the big items, you 24 know, the pump is on the head. You mentioned the 25 coolant level sensors. You could see the allocated 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
56 1 space for those.
2 The shutdown elements that are in the 3 core, there's three of those. They're indicated by 4 the red dash circles there, and then the 4X for 5 control elements by the yellow dash circles there.
6 And then you could see we currently have two means of 7 pebble insertion, material sampling boards, reactor 8 thermocouples, a location for a neutron source.
9 MEMBER BROWN: So you have two types of --
10 -
11 MR. DORON: Sorry.
12 MEMBER BROWN: You said this earlier. So 13 you've got two types of reactor. Okay, one of them's 14 a shutdown, okay, so one of them's shutdown, the other 15 one's control elements.
16 MR. DORON: Correct. And the next slides 17 are going to be discussing those.
18 MEMBER BROWN: And if one -- and you all 19 are doing, I think you mentioned this earlier, but if 20 one reactor shutdown accident element doesn't operate, 21 that's a pretty thin margin. I think Dave or somebody 22 made a comment about that.
23 MR. DORON: Yes. But we are allowing for 24 that.
25 MEMBER BROWN: And where are your sensors, 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
57 1 your neutron sensors? Those are the purple things?
2 MR. DORON: Yes, source range neutron 3 detectors.
4 MEMBER BROWN: What about power range or 5 in between, whatever your ranges are?
6 MR. DORON: I can let -- Nader, do you 7 mind speaking to the power detectors quickly?
8 MR. SATVAT: Sure. This is Nader Satvat.
9 The power range detectors are in the cavity, in the 10 bio-shield structure.
11 MEMBER BROWN: In the what structure?
12 MR. SATVAT: They're outside of the 13 reactor vessel.
14 MEMBER BROWN: Oh, so they're external to 15 the vessel. These are in core -- the source range are 16 in core, the other ones are ex-core.
17 MR. SATVAT: Yes.
18 MR. DORON: Ex vessel, rather.
19 MEMBER BROWN: Ex vessel, that's fine. I 20 meant ex vessel.
21 MR. DORON: Okay.
22 MEMBER BROWN: Okay. Well, not okay, I'm 23 just saying I got you.
24 (Laughter.)
25 MEMBER MARCH-LEUBA: This question might 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
58 1 not relate certainly in your presentation, but I 2 notice there are three detectors. I'm thinking I&C.
3 Are we going to have two out of three detection 4 systems?
5 MEMBER BROWN: I looked at that, and 6 there's no definition of what there's going to be.
7 It's just a box.
8 (Laughter.)
9 MEMBER MARCH-LEUBA: Well, if you have 10 only three detectors you're going to have close to 11 four. So think about it. We'll need to know.
12 MR. DORON: Okay. And maybe Anthony can 13 take that later.
14 (Simultaneous speaking.)
15 MEMBER REMPE: What is the reserve 16 instrumentation? What are you going to put in there?
17 MR. DORON: You know, whatever it is that 18 we think is appropriate at the time. This is a first 19 of a kind facility.
20 MEMBER REMPE: So I have seen thermal 21 couples listed, and I've seen the level detectors.
22 MR. DORON: Yes.
23 MEMBER REMPE: I'm kind of wondering what 24 else you're going to put in.
25 MR. DORON: There's lots of things we're 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
59 1 discussing. We're leaving it available.
2 MEMBER REMPE: Okay.
3 MEMBER BROWN: What's a neutron source?
4 MR. DORON: I don't know if we 5 specifically discussed which one is our neutron source 6 in PSAR.
7 MEMBER BROWN: I thought uranium fissioned 8 and produced its own neutrons.
9 MR. DORON: This is just for startup --
10 (Simultaneous speaking.)
11 MR. DORON: -- the neutrons are the 12 startup source.
13 (Simultaneous speaking.)
14 MEMBER BROWN: You need an external source 15 in order to start up the reactor?
16 MEMBER KIRCHNER: Charlie, you always put 17 a external source in the core to start up.
18 CHAIRMAN PETTI: Yes. It's either PuBe or 19 americium-beryllium, usually.
20 MEMBER KIRCHNER: Yes, americium-beryllium 21 is a common one. But almost all reactors have that.
22 So you have the signal when you begin startup. And 23 this goes towards those earlier questions.
24 MEMBER BROWN: I will not make any 25 comments on that.
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
60 1 (Laughter.)
2 MEMBER REMPE: So have you thought what 3 type of coolant level of the sensor you're going to 4 use yet?
5 MR. DORON: We have thought about it. And 6 again, I don't know if Anthony's going to go into that 7 level of detail.
8 MEMBER REMPE: Well, it's actually not in 9 the PSAR too. I mean, you mentioned thermal couple, 10 I don't know what kind of thermal couple, but the 11 other detectors are pretty much undefined. And I 12 assume it's not going to change before the PSAR is 13 finalized.
14 MR. DORON: Drew, do you want to let 15 Anthony go here, or do you want to take a note to 16 discuss those later?
17 MR. PEBBLES: Let's get to Anthony's 18 presentation, just in the interest of time. And he 19 can speak to the level of detail that we have in the 20 PSAR for the InP system.
21 MR. DORON: Okay. Okay, so Hermes 22 Reactivity Control and Shutdown System, again, this is 23 relatively high level. It's from the PSAR. So the 4X 24 core in the reflector, and 3B core shutdown elements, 25 so the ones in the reflector are control elements, the 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
61 1 ones in the bed are shutdown elements.
2 The drive mechanism is a motor-driven 3 sheave. It's to position the elements. And release 4 mechanism is those two release, essential release 5 mechanisms. One is an electromagnetic clutch, and the 6 second is a motor isolation.
7 If you look at the little diagram there on 8 the right, we have the elements, a counter weight, the 9 wire rope. There's a housing there, connector, the 10 elements to the wire rope, the sheave, the clutch, and 11 the motor. That is all.
12 On the left we have the control element, 13 and on the right we have the shutdown element. So 14 again, the control element enters a dedicated path in 15 the reflector structure, the element connector there 16 that connects it to the wire, we have the cap, the 17 element connection plates, control element segments.
18 The control element is a segmented annular 19 design. It's got individual capsules, argon filled.
20 The absorber is B4C, the cladding is stainless, 316H, 21 a little diagram there showing what a cross section of 22 the control element might look like.
23 The shutdown element is cruciform. It's 24 got, again, the connector on the top plate there, it's 25 cruciform design, inner cladding, it contains the 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
62 1 absorber. It's argon filled. And the absorber is 2 B4C. And the cladding is stainless steel 316H.
3 That is all. I appreciate all the 4 questions. Thank you very much for your time.
5 MEMBER REMPE: So you don't have to answer 6 it now but later. I know I saw in the PSAR the 7 comment about the B4C melting temperature was more 8 than 1,000 degrees C above the operating temperatures.
9 But I didn't see anything about liquefaction 10 temperatures with B4C and stainless steel.
11 And are you considering that too? Because 12 it seems like that's a lower temperature than the 13 melting temperature. It's still probably not a 14 problem, but you might want to think about it.
15 MR. DORON: Okay. We can take that one as 16 a note in the interest of time.
17 MEMBER REMPE: The other one to think 18 about, that I was wondering about was reading about 19 this. The PSAR dismisses any concern about 20 combustible gas generation. And I get that you may 21 not be so concerned about hydrogen, but what about, is 22 there no concern about any sort of carbon-related 23 combustible gas generation?
24 MR. DORON: You know, a good question. I 25 would go to our salt chemistry team to answer that.
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
63 1 I don't know, I'm not ---
2 (Simultaneous speaking.)
3 MEMBER REMPE: And even if it's not today, 4 it's just something to think about for future 5 discussions.
6 MR. DORON: Okay.
7 MR. PEBBLES: We'll take that back. Thank 8 you.
9 MR. DORON: Yes, appreciate that.
10 MR. ZWEIBAUM: All right, good afternoon.
11 My name is Nico Zweibaum. I'm the director of Salt 12 Systems Design at Kairos. I'm going to be talking 13 about heat transport as well as pebble handling and 14 storage system in Hermes. So my mission here is for 15 everyone to understand where the Flibe goes, where the 16 pebbles go, and everything around that.
17 So starting with our primary heat 18 transport system, or PHTS in short, that system in 19 Hermes is responsible for transporting the heat from 20 the reactor to the ultimate heat sync, which is air, 21 during power operation and during normal shutdown.
22 That system is carrying Flibe around. It 23 operates near atmospheric pressure. It does not 24 provide a safety-related heat removal function. The 25 safety-related heat removal system is our decay heat 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
64 1 removal system which I'll be talking about next.
2 One safety-related function of the PHTS 3 though is a hot lag anti-siphon feature. And that is 4 performed by the geometry of our primary salt pump.
5 That pump, which we alluded to but did not show in 6 Oded's talk, it's sitting on the vessel head. The 7 reactor vessel has this upper head, and the pump 8 connects to it.
9 And it has a downward facing inlet.
10 That's here the Flibe is going through the pump and 11 out to the hot lag. When the level drops, that pump 12 essentially deprimes, and this what's providing that 13 anti-siphon feature. So we're not draining coolant 14 outside of the vessel, especially not below the normal 15 operating levels to keep the fuel covered.
16 A number of additional functions for that 17 PHTS, it contains the reactor coolants and directs the 18 flow between the reactor vessel and the heat rejection 19 sub-system. It is equipped to manage thermal 20 transients, maintain overall thermal balance that's 21 occurring as part of normal operations.
22 Since our coolant has a relatively high 23 freezing, melting temperature, it is equipped with 24 features to ensure that we maintain acceptable minimum 25 temperatures through makeup heating as necessary 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
65 1 during operations. It is able to drain to reduce for 2 acidic heat losses when we run into overcooling 3 transients. And it does provide for in-service 4 inspection, maintenance, and replacement activity.
5 MEMBER BROWN: How hot do you have -- how 6 high do have to keep the temperature for the fluoride 7 salt to keep it from solidifying?
8 MR. ZWEIBAUM: So the freezing temperature 9 of our Flibe is, I believe, around 460 degrees 10 Celsius. You'll see on Slide 23 our normal operating 11 temperatures, but the minimum nominal temperature 12 during operations is 550 C, so almost 100 C above 13 freezing.
14 MEMBER BROWN: So you have to keep it 100 15 degrees C above freezing at all times with another 16 system?
17 MR. ZWEIBAUM: You don't have to keep it 18 that high. That's the nominal temperature. You do 19 want to maintain a healthy margin above freezing 20 though, and this is what that makeup heating system 21 does, so maintaining it above the freezing temperature 22 of 460 C.
23 MEMBER BROWN: And how do you maintain 24 that uniformly throughout the system.
25 MR. ZWEIBAUM: We do have a thermal 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
66 1 management system that consists of a combination of 2 heaters and insulation. And we'll have a number of 3 demonstrations along the way to ensure that we know 4 how to handle Flibe and keep it molten in those 5 systems.
6 MEMBER BROWN: Is it stationary during 7 that period of time? Or is it still being pumped?
8 MR. ZWEIBAUM: It will be pumped at most 9 times except during a number of transients like system 10 blackout, for instance, where you would lose your 11 pump. And this is when we would get into the more 12 safety-related decay heat removal which I'll be 13 talking about in a moment.
14 MEMBER BROWN: Okay. Thank you.
15 CHAIRMAN PETTI: Just a question. This 16 whole issue of the draining, and preventing freezing, 17 does that make that part of a system safety grade or 18 not?
19 MR. ZWEIBAUM: No. The safety case is 20 really around keeping the vessel and the fuel intact.
21 And so it's really about maintaining low enough 22 temperatures to not compromise the integrity of the 23 vessel service.
24 CHAIRMAN PETTI: But if you were to freeze 25 the coolant, that would not be a good day, right?
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
67 1 MR. ZWEIBAUM: Hold on a second.
2 (Simultaneous speaking.)
3 CHAIRMAN PETTI: Would that lead to an 4 event you need to ---
5 MR. ZWEIBAUM: That is more of an 6 investment protection feature and less of a safety 7 concern. It is something that we'll want to maintain 8 for our own, I mean, to maintain the plan. But that 9 is not in the safety space.
10 MEMBER KIRCHNER: Dave, this is Walt.
11 Could we ask anyone, everyone on the line who is not 12 a speaker to mute their microphones. We've got 13 background noise. Someone's having lunch somewhere 14 out there.
15 MEMBER REMPE: This is Joy. And I think 16 from the way the colors are flashing on the screen 17 this is coming from the conference room which may make 18 it hard to mute yourselves if you're talking, but 19 think about it, okay.
20 MR. ZWEIBAUM: Yes, I think people are 21 being pretty disciplined here, but we'll keep it in 22 mind.
23 I'll keep going here, talking through what 24 that PHTS system is made of as far as subsystems or 25 components. We have our reactor coolant, obviously, 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
68 1 which is Flibe, that primary salt pump I mentioned 2 before, which is a variable speed cartridge-style pump 3 that's attached to the vessel head. It's inlet 4 extends downwards through the free surface, and this 5 is how the coolant gets into the pump and out to the 6 PHTS.
7 We have a heat rejection subsystem. That 8 subsystem provides for heat transfer from the reactor 9 coolant to atmosphere. It consists of a radiator, a 10 heat rejection blower that circulates air across, and 11 associated ducting and thermal managements.
12 We have our primary loop piping which is 13 what the Flibe is circulating through, and primarily 14 thermal management which, as mentioned earlier, 15 provides non-nuclear heating and insulation as needed 16 for various operations to keep the system at desired 17 temperatures.
18 On the next slide, this is a table and a 19 figure that, I believe, are actually strictly from the 20 PSAR but giving you a very, very rough sense of how 21 the system is configured on the right. So you do see 22 the reactor vessel in a much less exciting fashion 23 than what Oded was showing.
24 But you do see the primary salt pump on 25 the upper right of that vessel, through which the 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
69 1 coolant goes out off to the side to the heat rejection 2 radiator. This is where heat transfer occurs to the 3 atmosphere with that heat rejection blower and stack.
4 And the coolant comes back through coal bags back into 5 the reactor vessel.
6 The thermal duty, as mentioned in the core 7 design portion, is 35 megawatts thermal. We do plan 8 on having a single heat rejection radiator, single hot 9 lag, two coal bags to return into the vessel. The 10 primary loop line size is generally envisioned to be 11 somewhere between 8 and 12 inch nominal pipe size.
12 The hot lag temperature, if you will, 13 before the coolant gets into that heat rejection 14 radiator, will be somewhere between 600 and 650 15 Celsius, depending on operational modes. The cold lag 16 temperature is 550 C. Nominal flow rate is 210 17 kilograms per second, and the design pressure is 18 generally estimated at 525 kilopascals.
19 So this was for the PHTS which is our non-20 safety-related heat transport system.
21 MEMBER BROWN: How many kilopascals did 22 you say?
23 MR. ZWEIBAUM: Five hundred and twenty-24 five.
25 MEMBER BROWN: Do you have that in pounds 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
70 1 per square inch?
2 MR. ZWEIBAUM: I will in one second, 76 3 psi.
4 MEMBER BROWN: Okay, thank you. I came 5 that close to that. All right, I just want to make 6 sure I was right, thank you.
7 MR. ZWEIBAUM: That is the design pressure 8 though, that is not the anticipated operating 9 pressure.
10 MEMBER BROWN: How much lower do you 11 anticipate that to be?
12 MR. ZWEIBAUM: We'd be closer to 13 atmospheric pressure during normal operations.
14 MEMBER BROWN: Okay. All right, thank 15 you.
16 MR. HUGHES: This is Joel Hughes. I'm the 17 responsible engineer for the primary heat transfer 18 system. So just maybe one quick clarification. So 19 the carbon gas pressure at the inlet of the pump is 20 quite near atmospheric pressure. But the pump 21 obviously does add some pressure to it. It will be a 22 fair bit below that 525 kilopascal.
23 But it kind of depends on what your 24 definition is in terms of close to atmospheric 25 pressure. But it certainly adds some pressure at the 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
71 1 outlet there. And that's consumed along the flow path 2 back around the PHTS through the vessel back to the 3 inlet of the pump.
4 MEMBER BROWN: Okay, thank you.
5 MEMBER KIRCHNER: Joel, while you're on 6 the line, this is Walt Kirchner, how does the layout 7 break the seal? You've got the pump inlet stuck, not 8 stuck, intentionally positioned under the free 9 surface. Under normal operation, how many inches, or 10 meters, or whatever measurement you use, is that? And 11 what breaks the suction if you have a break in the 12 primary loop?
13 MR. HUGHES: Excellent question. So I 14 think as Oded mentioned, we'd have to define the exact 15 elevation of the pump inlet. But that downward 16 facing, basically, inlet of the pump would break the 17 suction on the hot leg side. So if we had a break in 18 the primary salt piping, you could pull a siphon, 19 right, and then down as the level of Flibe in the 20 vessel kind of travels downwards, and Flibe is leaving 21 the system. At some point it would break at the inlet 22 of the pump, specifically above the core level. I 23 don't know exactly how many inches above.
24 MEMBER KIRCHNER: Okay, okay.
25 MR. HUGHES: And then there's always a 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
72 1 similar --
2 (Simultaneous speaking.)
3 MEMBER KIRCHNER: -- above the core?
4 MR. HUGHES: Yes, that's the idea. And 5 then there would be, like, kind of a similar feature.
6 It might look geometrically different, but 7 functionally similar on the cold leg side as well so 8 that we don't siphon through the downcomer.
9 MEMBER KIRCHNER: Right, right. Okay, 10 thank you.
11 MR. HUGHES: Sure.
12 MR. ZWEIBAUM: So on to our safety-related 13 decay heat removal system, that is our DHRS, you see 14 a diagram of the configuration here on the left. So 15 the purpose of that system is to provide vessel 16 protection during postulated events for which the PHTS 17 we were talking about previously, is unavailable.
18 How this system works is based on in-19 vessel natural circulation. Oded mentioned that 20 before as part of what happens inside the vessel. So 21 you see the vessel represented here. But really what 22 this system is about is what's around it.
23 So it's a water-based ex-vessel system, 24 and the heat transfer modes are via thermal radiation 25 and convection. It is a system that operates through 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
73 1 continuous direct roll-off when the decay loads exceed 2 for acidic losses. That system is actually shut off 3 and isolated from the system when we're operating at 4 no or low power levels. In that case, we can rely on 5 heat removal via for acidic losses only. We're not 6 relying on the roll-off feature.
7 And the main thing on operation is that 8 this system gets activated when we cross some power 9 threshold. But after that, the system's status has 10 not changed. The state of that system does not change 11 on reactor event initiation. So when that DHRS, which 12 is a passive decay heat removal system, is called upon 13 for decay heat removal from the vessel, the system is 14 already containing water and ready to boil off.
15 This is kind of a self-regulated mechanism 16 in that the removal rate is directly a function of 17 vessel temperature. Since the primary mode of heat 18 transfer between the vessel and the DHRS is by thermal 19 radiation heat transfer, which is directly dependent 20 on temperature, which is important since the main 21 metrics that we're trying to control are going to be 22 peak temperatures of that vessel surface.
23 So you can see the configuration on the 24 left with the vessel that is facing those annular 25 thermosiphons. Those are connected to a water storage 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
74 1 tank via some piping and a separator where there is 2 the separation between the liquid water that comes in 3 and steam that comes out after boil off.
4 The storage tank is vented to atmosphere, 5 and so as the steam comes out, we do have that getting 6 out from the system through that upper penetration --
7 MEMBER MARCH-LEUBA: I have a couple of 8 questions.
9 MEMBER BROWN: Yes, that cavity the vessel 10 sits in, is that just air? And therefore you said 11 radiation from the vessel to the rods or whatever, the 12 annular thermosiphon.
13 MR. ZWEIBAUM: Yes.
14 MEMBER BROWN: So there's nothing in 15 there. It's just a dead air space, and then depending 16 on radiation and whatever convection flow of the air 17 within that space?
18 MR. ZWEIBAUM: That is correct.
19 MEMBER BROWN: So it's not a wrap-around, 20 is what I'm trying to get, where it's in contact with 21 the vessel?
22 MR. ZWEIBAUM: That is correct.
23 MEMBER MARCH-LEUBA: So this is Jose. How 24 many thermal cycles are there, I assume when you 25 designed it? I'm sure there is not only two.
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
75 1 MR. ZWEIBAUM: No, there is not only two.
2 There is a bit more detail on the next slide. So 3 maybe we can go through that. And as far as the --
4 MEMBER MARCH-LEUBA: Hold on, let me ask 5 my second question. Maintaining the inventory in the 6 storage tank up there, is it a safety function?
7 MEMBER MARCH-LEUBA: No.
8 MEMBER MARCH-LEUBA: Because if you run 9 out of it, then you have a problem. And if you are 10 constantly operating, you are constantly boiling it 11 off.
12 MR. ZWEIBAUM: Yes. So the system is 13 sized for that.
14 MEMBER BROWN: Pardon?
15 MR. ZWEIBAUM: The system is -- sorry, I 16 don't want to talk over you.
17 MEMBER MARCH-LEUBA: Yes, you said that 18 the system is sized for it, but things tend to go 19 wrong sometimes. I mean, I would have, at least in 20 the protection system, or certainly in the alarm 21 system, the level is too low.
22 MR. ZWEIBAUM: Yes. So there would be 23 some level where we would need to shut down. I may --
24 we have the responsible engineer for the decay heat 25 removal system, Casey Tompkins, on the line. So maybe 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
76 1 he can speak to that specific question.
2 MEMBER MARCH-LEUBA: No, just so you're 3 thinking about it, then we'll look. When we have 4 details, we'll look into it.
5 MR. ZWEIBAUM: Okay. That's all right 6 then. We'll keep going.
7 MEMBER BROWN: The point is you're venting 8 to atmosphere, so you're going to be losing water when 9 you're really hot.
10 MR. ZWEIBAUM: Yes. That is part of the 11 operations. We are expecting that.
12 MEMBER BROWN: And therefore you're going 13 to lose water.
14 MR. ZWEIBAUM: Can we get to the next 15 slide? Maybe that will get into a bit more detail 16 here that might explain some of this.
17 So maybe, speaking to the point that was 18 just made, before I go through the contents of the 19 slide, but you can see that that storage tank is 20 actually connected to a feed water system.
21 So during normal operation, you'll 22 constantly be replenishing that storage tank.
23 However, you're not relying on that feed water when 24 the system is called upon during a transient. So 25 there will be a normal operating mode where you do 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
77 1 have feed water and, I guess, a transient mode or a 2 postulated event mode where you would not have that 3 feed water. And you would be boiling off your 4 inventory that's in there.
5 MEMBER MARCH-LEUBA: And are you planning 6 to size it for the conventional 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, or those 30 7 days or --
8 MR. ZWEIBAUM: Yes.
9 MEMBER MARCH-LEUBA: It was an either/or.
10 MR. ZWEIBAUM: Seventy-two, sorry. I 11 started replying after the first half of your 12 sentence.
13 MEMBER MARCH-LEUBA: Okay, thank you.
14 MEMBER HALNON: Yes, this is Greg Halnon.
15 Is it just one storage tank, or do you have two, 16 three, just one?
17 MR. ZWEIBAUM: There are four. So let me 18 go through the contents of this slide. The first 19 point, but obviously by now this is clear, is that 20 that DHRS is independent from the primary coolant.
21 It's a water-based system, so it's isolated from the 22 Flibe system.
23 One other thing that I mentioned earlier 24 is there is no change of state on setup postulated 25 events. So that system is always on when we cross 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
78 1 some set power level.
2 But to a question that was asked multiple 3 times, there are four independent cooling loops. And 4 there is a three out of four kind of logic here where 5 we are sizing the system so we can lose one of those 6 four and still be within our envelope.
7 There is also a dual walls configuration 8 here. So if you look at the symbol, it is contained 9 within a deeper kind of shroud, if you will, so that 10 we can continue to have heat removal in the presence 11 of a water leak within this.
12 And there is one active component to note 13 here which is an isolation valve between the storage 14 tank and the thimbles, which is closed at no to low 15 power, that gets opened when we cross some threshold 16 power but then remain open.
17 And so this isolation valve failing in 18 place means that the operating system continues to 19 operate during a postulated event. And then we have 20 a flowed valve inside the separator that passively 21 regulates the flow of water from the storage tank to 22 the thimbles so as not to clog them. But that's 23 during normal operations. But that flow valve not 24 only failed to open so that we don't risk dry out of 25 the thimbles during a postulated event.
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
79 1 MEMBER KIRCHNER: This is Walt Kirchner.
2 Just a further detail. Go to the next slide. It's 3 fine. Yes. Is the system required, probably this 4 would be more tech specs kind of issue, to keep the 5 reactor vessel within its designed thermal limits?
6 MR. ZWEIBAUM: Yes, we will have tech 7 specs around that.
8 MEMBER KIRCHNER: Okay, thank you.
9 MEMBER BROWN: So this, you said there is 10 no change in state relative to postulated events, but 11 it's always on when you cross some power level. So 12 when you startup and you get to some predetermined or 13 calculated power level, then that's system is placed 14 and it's always on configuration.
15 So it's removing heat during all power 16 range operations --
17 MR. ZWEIBAUM: Yes.
18 MEMBER BROWN: -- except if you go below, 19 whatever the number is, and then it goes off again?
20 MR. ZWEIBAUM: Yes.
21 MEMBER BROWN: So, some type of sensors 22 tell you that?
23 MR. ZWEIBAUM: Yes.
24 MR. PEBBLES: So that's correct. This is 25 Drew Pebbles. I just wanted to make that 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
80 1 clarification. We're going to have a tech spec on 2 DHRS operability, which will likely include level and 3 other things in the tank.
4 That is for the initial conditions, but 5 it's not for maintaining reactor vessel temperatures 6 during normal operations.
7 MEMBER BROWN: So you'll also need them, 8 because you've got to feed into it, there has got to 9 be some type of minimum level you allow in the storage 10 tank? I mean, I presume that's part of your overall 11 configurations?
12 MR. PEBBLES: That's likely what it's 13 going to be for the PSAR level. We're only required 14 to mention the operability tech spec. The specific --
15 MEMBER BROWN: Yes, that's fine.
16 MR. PEBBLES: Yes. We'll be providing 17 that with the operating license application.
18 MEMBER BROWN: Okay. Thank you.
19 MR. PEBBLES: Yes.
20 MR. ZWEIBAUM: So the next three slides 21 kind of illustrate, in hopefully more clear ways, what 22 I was trying to describe as far as the three main 23 modes of operation.
24 So initially, as the core is at low to no 25 power, that isolation valve between the water storage 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
81 1 tank and the thimbles is closed. So the storage tank 2 is full of water, the thimbles are dry. And the only 3 heat that comes out of the vessel is for acidic heat 4 loss, but there is no direct heat transfer to water 5 and the thimbles.
6 MEMBER BROWN: You said the valve closes, 7 or opens. So it's, somehow it's designed such that 8 it's always going to go open if something fails?
9 Whatever that something is.
10 MR. ZWEIBAUM: Well, it would fail as is.
11 So in this case we are not relying on having water in 12 the thimbles to extract enough heat. So if there were 13 any failure in, in the current configuration that 14 you're seeing on the slide, then we're not relying on 15 the DHRS for decay heat removal anyways.
16 MEMBER BROWN: Yes, so the valve would be 17 closed if you go to low power, right?
18 MR. ZWEIBAUM: Yes.
19 MEMBER BROWN: But so, something has to 20 make it open.
21 MR. ZWEIBAUM: Yes.
22 MEMBER BROWN: If we go up above a certain 23 power.
24 MR. ZWEIBAUM: Yes, absolutely.
25 MEMBER BROWN: And what, the failure mode 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
82 1 you're saying is open, but if you're at low power and 2 -- so it's powered to stay shut, and then 3 theoretically if you lose power it opens up? That's 4 just a possible. Is that what you're saying?
5 MR. TOMPKINS: Hi, this is Casey Tompkins 6 --
7 MR. ZWEIBAUM: Also -- yes, go ahead.
8 MR. TOMPKINS: -- responsible engineer for 9 the decay heat removal system. So the valves fail in 10 place. So like if it's open and we lose power or 11 signal to it, it remains open. If it's closed, it 12 remains closed.
13 MEMBER BROWN: Ah.
14 MR. TOMPKINS: So if we don't, so if the 15 system is not running it's because we don't need it on 16 a postulated event. So then there is no reason for it 17 to change positions. And vice versa.
18 MEMBER BROWN: Okay.
19 MR. TOMPKINS: If it's open, then we need 20 it so it stays open.
21 MEMBER BROWN: So once it opens it will 22 stay open, if power goes away, and once it's closed it 23 will stay closed if whatever closed it goes away?
24 MR. TOMPKINS: Correct.
25 MR. ZWEIBAUM: So this is Nico Zweibaum 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
83 1 again. So, the transition between this slide and the 2 next slide is really what happens as you get above 3 those, this threshold power level.
4 So this is really normal operation of 5 Hermes. Your core is operating, well, it says high 6 power but really is power above that decline 7 threshold, but is nominal power for instance.
8 So in this case you got your line between 9 your feedwater and your storage tank that is open.
10 You also open the, or your isolation valve that was 11 between the storage tank and the thimbles is open.
12 And you're continuously flowing water through those 13 thimbles, boiling up and the steam gets vented out to 14 the atmosphere.
15 And then if you go to the next slide.
16 During the postulated event where you have a reactor 17 trip and you can't rely on your primary heat transport 18 system to extract heat, then you would have this 19 continuous boil-up of the inventory that was in your 20 storage tank.
21 So we're sizing to not be relying on the 22 feedwater system feeding water into the storage tank, 23 but instead we're boiling up the inventory of water 24 that is in those storage tanks.
25 MEMBER KIRCHNER: So, might I ask a 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
84 1 question on this? This is Walt Kirchner again. What 2 limits your design here in the three modes of 3 operation, is it the concrete temperature, is it 4 vessel temperature or is it decay heat removal?
5 MR. ZWEIBAUM: Well, the system is spliced 6 to protect against -- the main metric that we're after 7 is the vessel heat temperature. To avoid failure of 8 that structure.
9 MEMBER KIRCHNER: Right. Is that during 10 normal operation as well or just under the transient?
11 MR. ZWEIBAUM: Just under the transient.
12 During normal operations, your main means of heat 13 removal is through the primary heat transport system.
14 MEMBER KIRCHNER: Of course. But is 15 there, does that keep the temperature, well, I guess 16 the downcomers, the inner wall actually of the vessel.
17 So --
18 MR. ZWEIBAUM: That's right. Yes. And 19 that's where you have --
20 MEMBER KIRCHNER: Yes.
21 MR. ZWEIBAUM: -- coming back around 550 22 Celsius.
23 MEMBER KIRCHNER: Yes. Yes. So then what 24 about the concrete in the cavity. What temperate is 25 the concrete steam?
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
85 1 MR. ZWEIBAUM: Let me ask our manager to 2 answer this one if we --
3 MR. SONG: We did a --
4 PARTICIPANT: Who are you?
5 MR. SONG: Oh, sorry.
6 MEMBER KIRCHNER: It's kind of a leading 7 question because you would have to stay below you, you 8 know, your ACS or ACI. I forget the code.
9 (Simultaneously speaking.)
10 MEMBER KIRCHNER: American Concrete 11 Institute limits. If that, if indeed, the chamber 12 here is concrete.
13 MR. SONG: Yes. This is manager of steel 14 structure, Brian Song. And yes, we are considering 15 that. And considering to have the concrete 16 temperature beyond the limit of ACI 39 that you 17 described.
18 So that will be considered with the 19 thermal management system, so we will, that is a 20 consideration that we have.
21 DR. BLEY: This is Dennis Bley.
22 MEMBER KIRCHNER: Thank you.
23 DR. BLEY: On this sketch you show the 24 feedwater valve closed. Now, you wouldn't have 25 feedwater, but do you actually close it in case you do 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
86 1 have feedwater? This is covered in several different 2 kinds of events.
3 MR. ZWEIBAUM: I mean, if we have 4 feedwater available then we could be constantly 5 replenishing the storage tank. We're not forcing that 6 closed. But we are designing the system --
7 DR. BLEY: That's what I thought.
8 MR. ZWEIBAUM: -- to operate with it 9 closed.
10 DR. BLEY: You're just saying there might 11 not be feedwater and you're fine then. Okay.
12 MR. ZWEIBAUM: Correct.
13 DR. BLEY: Thanks.
14 MEMBER KIRCHNER: And just one follow-up 15 question. This is Walt Kirchner again. The way 16 you're showing the system there with the tank outside 17 the primary, poor choice of words, whatever the 18 reactor building is called, then this would be a 19 safety grade, or a safety-related system and be 20 hardened and protected against missiles, et cetera?
21 MR. ZWEIBAUM: Yes. The entire DHRS is 22 safety-related.
23 MEMBER KIRCHNER: Right. So then that 24 would have to be in a hardened enclosure.
25 MR. ZWEIBAUM: Yes. To be more precise, 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
87 1 the portions of the DHRS are required to perform the 2 safety-related heat removal function, will be 3 protected by the structure.
4 So, the feedwater portion, which is not 5 required for the safety-related heat removal function 6 may not necessarily be protected.
7 MEMBER KIRCHNER: Yes. No, I get that 8 part. I was thinking of the tank itself.
9 MR. ZWEIBAUM: Right.
10 MEMBER KIRCHNER: For missile protection 11 and seismic considerations.
12 MR. ZWEIBAUM: Yes. That is protected.
13 MEMBER BALLINGER: This is Ron Ballinger.
14 I keep looking at this and I keep thinking t to the 15 forth radiated heat transfer. And I keep wondering 16 what kind of uncertainty might there be in all of this 17 system because much of a change in temperate means a 18 lot of changes in heat transfer.
19 I'm assuming that there will be an 20 uncertainty analysis done of this whole system.
21 MR. ZWEIBAUM: Yes. Casey, do you want to 22 take this one for more detail?
23 MR. TOMPKINS: Yes, sure. This is Casey 24 here. So, because the temperature of the DHRS in our 25 operation is pretty low, changes in that temperature 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
88 1 don't really effect heat removal too much. The 2 temperature heat removal is mostly driven by the 3 vessel temperature.
4 But in terms of the heat and defectors, 5 there is uncertainty there, so we'll have to look at 6 that. But for the most part we'll have correct test 7 data on the anticipate heat removal from individual 8 thimbles under prototypical cavity conditions that 9 will give us higher confidence in what our removal 10 rates are. And we have codings that we're looking 11 into that give us more predictability.
12 MR. PEBBLES: And this is Drew Pebbles 13 again. Just to be clear, these are forward looking 14 statements right now for the PSAR. We don't have that 15 level of detail in the application. But qualification 16 of the system is done for the operating license 17 application.
18 MEMBER BALLINGER: Thank you.
19 MEMBER KIRCHNER: This is Walt Kirchner 20 again. Just a, this is probably a detail for the 21 future. But with these thimble enclosures inside the 22 cavity, the large flat plates that maximize the area 23 and protect the concrete, were they just around 24 annually, annulus structure of --
25 MR. ZWEIBAUM: They're around annulus 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
89 1 structures, but you have a fair amount that's around 2 the vessel.
3 MEMBER KIRCHNER: Okay. Which four --
4 MR. ZWEIBAUM: We're obviously only 5 showing one here but --
6 MEMBER KIRCHNER: Yes. Okay. Thank you.
7 MEMBER REMPE: You know, when I think 8 about Ron's question and Dave's earlier question at 9 the beginning of the meeting, this mockup that you're 10 getting ready to build, can you use it?
11 I know it's not in the PSAR, but is there 12 a vision that you might try and mock that up in that 13 facility and quantify some of the uncertainties?
14 MR. ZWEIBAUM: Are you referring to the 15 engineering test unit?
16 MEMBER REMPE: Yes. The one that's right 17 before Hermes that looked like it was going to be the 18 same scale, but when Dave was asking about surface 19 heat transfer, or heat fluxes, I don't think we heard 20 an answer to it. It's the --
21 MR. ZWEIBAUM: Right.
22 MEMBER REMPE: -- called the U-facility.
23 That's what it's called.
24 MR. ZWEIBAUM: So the U-facility is after 25 Hermes. The ETU --
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
90 1 MEMBER REMPE: Oh, you're right.
2 MR. ZWEIBAUM: -- is isothermal so we're 3 not including the DHRS. But there will be a separate 4 testing program for the DHRS to qualify it.
5 MEMBER REMPE: You're right. It's the one 6 that was before Hermes I was asking for. But you have 7 another test program that will be used for this?
8 Okay, got it.
9 MR. ZWEIBAUM: Right.
10 MEMBER BALLINGER: Just --
11 CHAIRMAN PETTI: Can you --
12 MEMBER BALLINGER: -- there's got to be a 13 lot of uncertainty. You know, plus or minus an inch, 14 excuse me, 2.54 centimeters would make a heck of a 15 difference.
16 CHAIRMAN PETTI: So just, I'm just 17 wondering if you, you guys are probably aware of the 18 tests that were done at Argonne for these types of 19 heat removal systems. They did air. And then I 20 believe they were going to do steam. Whether or not 21 that geometry would be helpful here with what they're 22 doing.
23 MR. ZWEIBAUM: Do we want to get into the 24 details?
25 MR. PEBBLES: I think we'll take that 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
91 1 back.
2 CHAIRMAN PETTI: Okay.
3 MR. PEBBLES: But --
4 CHAIRMAN PETTI: Yes, I just, I don't 5 know, I've lost track as to whether or not they got 6 funded to do the steam. I know they did the air. But 7 there may be something --
8 MR. PEBBLES: We did work with Argonne, we 9 did work with that facility. And we are also planning 10 on our internal campaigns to compliment that with more 11 prototypic conditions.
12 CHAIRMAN PETTI: Ah. Okay, thanks.
13 MR. ZWEIBAUM: Okay, so --
14 MEMBER MARCH-LEUBA: Another question.
15 All this is contingent on natural circulation of flow 16 working inside the vessel. How much margin do we have 17 on the Flibe volume?
18 I mean, how much inadvertent draining of 19 the Flibe can you tolerate? I mean, I'm working the 20 PRA here in my head and inadvertent drain of the 21 vessel by a couple of inches will stop the, not the 22 circulation and you're dead in tracks.
23 MR. PEBBLES: So the --
24 MEMBER MARCH-LEUBA: And I realize that 25 you have a procedure to drain it, but the PRA should 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
92 1 have one branch on the tree to handle that.
2 MR. PEBBLES: So, a couple of points 3 there. The detailed analysis wouldn't be until OOA.
4 But for a PSAR we are committing to keeping the active 5 core covered.
6 Nico mentioned the anti-siphon device, 7 which does define a lowest level for the postulated 8 event that we consider.
9 MEMBER MARCH-LEUBA: Right. But the 10 preliminary potential conceptual cartoon design, I 11 need to be convinced that you don't have inadvertent 12 draining that stops the natural circulation. I need 13 to be convinced that you have looked at it.
14 MR. PEBBLES: Yes. So if the core, if the 15 fuel remains covered, than the path for natural 16 circulation will be active. We are designing with 17 that logic in mind since we have to maintain the fuel 18 covered, in that condition the natural circulation 19 test will be there.
20 MR. ZWEIBAUM: I'm also going to let 21 Darrell Gardner weigh in here.
22 MR. GARDNER: So this is Darrell Gardner.
23 I'm the senior director of licensing for Kairos Power.
24 I think it's important, as I listen to conversation, 25 lots of good questions.
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
93 1 Many of these questions are related to 2 details of the design that are appropriate for a final 3 safety analysis report. I think it's also important 4 to remember that the findings at the PSAR stage are 5 different than those at the FSAR stage.
6 And so, conclusions and determinations 7 about safety acceptability are completely different.
8 So while I understand the comment, I think we need to 9 sort of pull back and remember what's required by the 10 regulations at this phase.
11 MEMBER MARCH-LEUBA: So the regulations 12 don't require the thing work?
13 MR. GARDNER: I'm sorry, I didn't 14 understand the question.
15 MEMBER MARCH-LEUBA: The regulations don't 16 require that the thing work safely?
17 MR. GARDNER: The regulations require that 18 we describe the safety, that we describe the systems 19 and the design criteria and the margins to safety.
20 That's what's required to get a construction permit.
21 When we come back for the FSAR, the 22 demonstration of how these things work is, that's 23 where that demonstration is satisfied.
24 MEMBER MARCH-LEUBA: Okay.
25 MR. GARDNER: There is no, there is not a 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
94 1 determination of safety acceptance at this stage of 2 the review.
3 MR. PEBBLES: Unless it's requested by the 4 applicant.
5 MR. GARDNER: Unless we request that. And 6 we have not requested that the staff make a 7 determination of safety acceptability at this time.
8 MEMBER MARCH-LEUBA: Okay. And I will 9 make sure that the ACRS letter says that in the first 10 paragraph. That we have no idea about the safety of 11 these reactors.
12 MR. GARDNER: Well, I'm not sure I would 13 necessarily agree with that comment. I think I would 14 suggest that you may not know all the details of how 15 it's satisfied at this stage.
16 MEMBER MARCH-LEUBA: You're -- I'm giving 17 you a, have you thought about this possible accident 18 in your conceptual design and you're telling me to get 19 lost. So I receive your comment.
20 MR. GARDNER: I don't think we're saying 21 that at all. I think we're trying to set the 22 framework for the questions that need to be resolved 23 at this stage of the review versus at a different 24 stage of the review.
25 MEMBER MARCH-LEUBA: I'll reserve my 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
95 1 questions --
2 CHAIRMAN PETTI: Fair enough.
3 MEMBER MARCH-LEUBA: -- for the Staff.
4 CHAIRMAN PETTI: Fair enough at this 5 point. Can I just ask a question? In terms of your 6 slides, A, we need a break. We'll also need the Staff 7 to talk. Where are we in terms of slides left?
8 MR. PEBBLES: So, two/thirds into it.
9 CHAIRMAN PETTI: Two/thirds?
10 MR. PEBBLES: Yes. We had, we have 11 another hour's worth of slide material.
12 CHAIRMAN PETTI: Another hour. That would 13 put us at 3:00. Okay, let's just keep going. We'll 14 also probably want a break. I thought the natural 15 break would be between you guys and the Staff, but so, 16 Members, if anyone feels like we need a break before 17 that, let me know. But let's just keep going because 18 I fear we are falling further behind. Is that 19 probably true?
20 MR. PEBBLES: Yes.
21 MR. ZWEIBAUM: Yes.
22 CHAIRMAN PETTI: This always happens, so.
23 (Laughter.)
24 CHAIRMAN PETTI: We're just so interested 25 in all the details. Let's keep going. Thanks.
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
96 1 MR. ZWEIBAUM: Okay. Next system is 2 changing gears a little bit, but this is about the 3 pebble handling and storage system.
4 Again, our fuel comes in pebble form. So 5 this is really the system that handles, moves the fuel 6 around and stores it. From initial onsite received 7 through in process circulation down to final onsite 8 storage.
9 A number of key sub-systems, one is the 10 pebble extraction machine that sits on top of the 11 reactor vessel and extracts pebbles from the core.
12 This is a single screw mechanism that removes the 13 pebbles from the molten salt.
14 We have a pebble inspection system that 15 will perform flaw detection and burn-up measurement of 16 removed pebbles. We have a processing system that 17 will sort pebbles into appropriate buffer storage 18 channels based on pebble types.
19 We have an insertion system, which is a 20 separate wheel feeder mechanism that inserts pebbles 21 back into the reactor via an in-vessel insertion line.
22 We have a number of storage system 23 canisters. Each canister can store around 2,000 24 damaged or spent fuel pebbles in a non-critical 25 configuration.
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
97 1 We have a storage cooling area. That area 2 will be passively cooled in building for spent fuel 3 canisters. And we have a new pebble addition system 4 which stores fresh fuel and prepares them for 5 circulation via high temperature bake out.
6 The next slide is a set of animations to 7 show you kind of the journey of the pebble through the 8 system. So if we start at the bottom right is where 9 you can see this rough diagram of the reactor core.
10 That red dot here would be a fuel pebble.
11 If we go next, that pebble goes up the 12 pebble extraction machine through an off head 13 penetration down to the inspection station that I 14 mentioned earlier. At that stage the pebbles are 15 inspected.
16 We make the determination between fuel and 17 moderator pebbles. If a pebble is a moderator pebble 18 then next it gets sent to a moderator storage bin.
19 If it's a fuel pebble next it goes to the 20 burn-up measurement station. This allows us to know 21 what the burn-up level of the fuel is to know if we're 22 below or above the threshold where the pebble has 23 reached its end of life, or effective life for Hermes.
24 Then next that pebble would get into 25 processing. And next into buffer storage.
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
98 1 Now if we, next, we have other pebbles, 2 and that could be of any different type, then that 3 could also get stored into a number of other buffer 4 storage canisters.
5 And the last case, next, would be if, 6 through burn-up measurement we find that this is a 7 spent fuel pebble then it gets discarded and sent into 8 one active storage canister that is connected to the 9 PHSS inner gas boundary at all times.
10 Next. If you look at the bottom towards 11 the bottom right you can see the new pebble insertion 12 canister. This is where new or fresh pebbles would be 13 stored. Whenever we send pebbles to active storage we 14 insert new pebbles.
15 Those go through the same inspection 16 station that recirculated fuel goes through. In case 17 we can detect any flaws then those pebbles would be 18 discarded immediately. Otherwise, they get processed.
19 And next go into one last storage bin that would 20 contain pebbles with no burn-up. Essentially fresh 21 fuel.
22 CHAIRMAN PETTI: So can I ask a question?
23 What differentiates a new pebble from a moderator 24 pebble in terms of the inspection?
25 I'm assuming you were using gamma to 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
99 1 determine moderator from fuel, from irradiated fuel.
2 MR. ZWEIBAUM: Gareth, do you want to take 3 this? We have our, the responsible engineer for our 4 pebble handling system.
5 MR. WHATCOTT: Sure. No problem, Nico.
6 When we insert new fuel we will do those in sort of a 7 sequential fashion. So we'll be able to know that 8 this line of pebbles coming in are all new.
9 CHAIRMAN PETTI: Ah, okay.
10 MR. WHATCOTT: That way we can maintain an 11 inventory of how many pebbles we've introduced.
12 CHAIRMAN PETTI: Okay.
13 MR. WHATCOTT: To differentiate between a 14 moderator and fuel pebbles, you mentioned gamma.
15 That's certainly one option. Another option we're 16 looking into currently is temperature since moderator 17 pebbles won't have decay and so they should be 18 thermally at a different temperature.
19 CHAIRMAN PETTI: Ah.
20 MR. WHATCOTT: And we can detect that 21 earlier on before having put it through a gamma 22 spectrometer.
23 CHAIRMAN PETTI: Yes. I mean, you 24 probably are aware of, in pebble beds, this 25 measurement is critical and is not as easy as it 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
100 1 sounds or looks in a simple diagram like this.
2 You have, at least for the pebble beds 3 that I was aware of, you had like 30 seconds to make 4 the measurement. And signal to noise ratio, looking 5 for the cesium-137 peak, which is generally a good 6 strong peak, but in fuel with all the other stuff it's 7 not as easy as it sounds.
8 So anything, another measurement could be 9 quite, quite useful in case that one is difficult.
10 Yes.
11 MR. WHATCOTT: Yes. No, we certainly 12 recognize the challenge with making this burn-up 13 measurement. We engaged with Sandia National 14 Laboratory and are working on some experimental work 15 with them to make sure that we can, we provide enough 16 time to develop this technology because as you 17 mentioned, other pebble bed systems have shown that 18 it's a challenging measurement to make on freshly 19 removed fuel that has high radioactivity.
20 So, yes. Looking at, using something like 21 a thermal, a thermal camera to screen out pebbles is 22 something we'd like to do as well so we're not having 23 to scan moderator pebbles and waste that time of the 24 gamma specter spectrometer.
25 CHAIRMAN PETTI: Yes.
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
101 1 MEMBER REMPE: Dave, I had a couple of 2 questions here. And I know we're behind so answer 3 what you can in a hurry and save the rest of them for 4 later.
5 But first of all, the construction permit 6 indicates that the canisters for the spent fuel 7 storage pebbles are flooded. And then it also talks 8 about during a full core offload that the pebbles 9 aren't sorted, you just put them in a canister.
10 And I was curious whether those canisters 11 would be flooded, and if so, then I am curious about 12 how you dry them out. And if you're going to measure 13 the off gas, then how that system is going to work in 14 any details of interest.
15 And then, finally, I believe NEIMA 16 requires that folks think about the whole fuel cycle.
17 And I was curious about what you will ultimately do 18 with these canisters of pebbles.
19 Back in the GA days they talked about 20 pushing the rods out of the fuel assemblies to try and 21 reduce the volume of the waste. I'm not sure what you 22 do with the pebbles. Maybe you even know, Dave, what 23 they've done in Germany. I've seen articles where 24 people talked about trying to break them and separate 25 the particles from the graphite to reduce the volume, 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
102 1 or is this not part of the Kairos plan to think about 2 what they're going to do with spent pebbles?
3 MR. ZWEIBAUM: I'll just answer the first 4 question because I think is very relevant to the 5 current conversation and safety piece. I think as far 6 as the fuel cycle we might table that to a later 7 discussion.
8 So, to clarify, the idea of flooding, if 9 I know what you're referring to in the PSAR, is purely 10 based on the analysis that was done to ensure that we 11 don't have any critical configuration. So in a worst 12 case scenario, where the canisters would be flooded, 13 we are conserving that we are still not in a critical 14 configuration.
15 That being said, this is not an 16 intentional flooding of the canisters. The canisters, 17 I think the current baseline is that they would be 18 stored temporarily in a storage pool, but the 19 canisters would be sealed. So we wouldn't have any 20 water ingress into those canisters.
21 The flooding, in the context of the PSAR, 22 was only related to the analysis that was done to 23 ensure that we don't have any critical configuration 24 of the fuel at any point.
25 MEMBER REMPE: Okay, so that helps. So 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
103 1 this would be a rare event, and if you did have to do 2 something with those pebbles it would be a rare event 3 and it's not something that's a planned operational 4 thing where you have to worry about drying out pebbles 5 that --
6 MR. ZWEIBAUM: That is right.
7 MEMBER REMPE: That helps.
8 CHAIRMAN PETTI: Okay --
9 MEMBER REMPE: And then at some point I am 10 curious about what you're going to do with the fuel 11 from this when it's --
12 CHAIRMAN PETTI: So I can just tell you, 13 Joy, the Germans just, in AVR and THTR, they didn't do 14 anything to the pebbles. And it's, you know, it's the 15 one thing that a prismatic has as a benefit is you can 16 take the compacts out and reduce the volume.
17 They didn't do anything to burn the pebble 18 matrix off or anything. So they just had a really 19 large volume of waste to deal with.
20 MEMBER REMPE: But it was only a couple of 21 reactors and I assume people want to do more than one 22 or two reactors with this. And so, again, we need to 23 think of the whole fuel cycle now because I guess 24 congressmen folks put that in the bill when they were 25 thinking about these new reactors.
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
104 1 MR. ZWEIBAUM: Yes. The end of the pebble 2 journey, for those of you who wants to know, the 3 pebble insertion hopper that is sitting at the top of 4 the reactor vessel, that would take the recirculated 5 fuel, take it down a pebble insertion line and the 6 pebbles are reinserted through the bottom of the core.
7 And repeat. So that is it for the PHSS.
8 CHAIRMAN PETTI: And you do plan to mock 9 this up, right, somewhere along the line?
10 MR. ZWEIBAUM: Mock this up as far as 11 physical testing?
12 CHAIRMAN PETTI: Yes. Yes.
13 MR. ZWEIBAUM: Yes. We've done a number 14 of scaled tests already. And we will continue to do 15 that. This is in scope for the engineering test unit.
16 And we'll have a number of other tests to confirm 17 those processes.
18 CHAIRMAN PETTI: Great. Thanks.
19 MR. PEBBLES: All right. So just real 20 quick, Dave, we just wanted to check with you and see 21 if this is where you wanted to take the break or if 22 you wanted to wait till the end?
23 CHAIRMAN PETTI: No, let's at least get 24 through yours.
25 MR. PEBBLES: Okay. All right.
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
105 1 MR. SONG: All right, so I'm Brian Song, 2 I'm manager of civil structures. And I'll go over the 3 Hermes civil structural stuff. Mainly Chapter 3 of 4 PSAR.
5 So, as you can see here, the reactor 6 building is approximately 250 feet long and 100 feet 7 wide. And the philosophy here is to design, to 8 separate the design and decouple the safety-related 9 portion of the building and the non-safety-related 10 portion of the building, which contains the SSCs, to 11 consolidate protection.
12 The safety-related portion of this 13 building is approximately 180 feet long and 50 feet 14 wide. And the design strategy of modulated 15 inflexibility is considered to allow for speed of 16 construction. And it is a, we are trying to make that 17 as simple as possible. So, it's a simple 18 configuration.
19 The safety-related building structure uses 20 a based isolation. And the non-safety-related 21 building is surrounded of the isolated super 22 structure.
23 The safety-related reactor building base 24 slab is approximately at grade with isolator basement 25 below. And the foundations are transferred to loads 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
106 1 of stiff rock.
2 The safety-related structure and 3 reinforced concrete structure that is hybrid of casts 4 in place, and also pre-cast concrete structure 5 elements. The safety-related person is designed to 6 protect safety-related SSCs from internal and external 7 events. Including potential damage from the non-8 safety-related portion of the building.
9 To credit, safety function, safety-related 10 reactor building is to protect and support the safety-11 related SSCs. And is not confinement or containment.
12 The building is applying performance based 13 design principles to align criteria with credited 14 safety function.
15 As you can see here, the safety-related 16 portion of the reactor building is divided into cells.
17 And the cells contain all the safety-related SSCs in 18 the facilities. And also some of the non-safety-19 related SSCs.
20 And I think there was a question about the 21 DHRS, so the DHRS is included in the reactor building 22 cell that you see here.
23 The message related portion of the 24 building is comprised of maintenance halls, including 25 high-bay shelves, maintenance corridors, truck bay 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
107 1 auxiliary worker inhabited areas. And it is a steel 2 frame construction with an independent foundation 3 system that will consist of a max slab with grade 4 beams.
5 And the non-safety-related portion of the 6 reactor building does not contain any safety-related 7 SSCs. And this portion of the building is designed so 8 that the payload does not interfere with the safety 9 functions of safe SSCs located in the safety-related 10 portion of the building. Or, yes. That's what, yes.
11 So that's kind of what this slide is. Any questions?
12 MEMBER BALLINGER: Yes. So, this is Ron 13 Ballinger. So the moat is just a separator?
14 MR. SONG: The moat, the moat is, yes. It 15 has a -- so the moat wall has two functions. So 16 because it's base-isolated so it will protect from the 17 displacement of the safety-related portion. And yes, 18 it is a separation of the building.
19 So a separation from the safety-related to 20 the non-safety-related portion of the building. Yes.
21 MEMBER BALLINGER: So is it seismically 22 significant?
23 MR. SONG: So, currently we're considering 24 this not to be safety-related. Maybe I will ask one 25 of my subject expert, Ben, if you want to add on to 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
108 1 the comment there. Ben Koslow.
2 MR. KOSLOW: Sure. Thanks, Brian.
3 MR. SONG: Yes.
4 MR. KOSLOW: The moat is sized so that 5 under the ground motions inspected for the site that 6 we have ample physical space so that the safety-7 related building does not come in contact with the 8 non-safety-related building. And then any of the 9 distribution systems that cross that gap have adequate 10 flexibility to accommodate that expected deformation 11 as well.
12 MEMBER BALLINGER: Does it have any 13 function to deal with thermal expansion because you're 14 dealing with very significant temperature differences 15 in various parts of that building?
16 MR. KOSLOW: So by the time you get out to 17 the moat, which is a fair distance away from the 18 reactor, it's not anticipated to have extreme 19 temperature fluctuations.
20 MEMBER BALLINGER: Okay.
21 MR. KOSLOW: Certainly the temperature 22 profile is accounted for when sizing things.
23 MEMBER BALLINGER: Thanks.
24 CHAIRMAN PETTI: Sometimes people might 25 call the moat a seismic gap. I've seen that in other 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
109 1 designs.
2 MEMBER BALLINGER: That's what I was kind 3 of thinking is what it was.
4 CHAIRMAN PETTI: Yes. Yes.
5 MEMBER KIRCHNER: Yes.
6 CHAIRMAN PETTI: So let me just ask a --
7 (Simultaneously speaking.)
8 MEMBER KIRCHNER: Dave, can I ask a 9 question?
10 CHAIRMAN PETTI: Yes, go ahead.
11 MEMBER KIRCHNER: This is Walt Kirchner.
12 Are you planning, for the safety part of the building 13 there, the inner part that's isolated, are you 14 planning on using steel plate composite concrete 15 construction?
16 MR. KOSLOW: Currently we're not. We are 17 considering precast concrete and cast in place as a 18 hybrid. However, that can be considered during our 19 design iteration we might, we'll see if that is 20 appropriate.
21 MEMBER KIRCHNER: It's just that this is 22 just an observation, not a request. It's just one 23 member.
24 You might look at that as an option for 25 the building that's isolated in terms of just ease of 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
110 1 construction vis-a-vis casting concrete and isolating 2 the concrete cast, complete cast structure. It's just 3 a thought. It's an observation, it's not a request.
4 MR. KOSLOW: Yes. Thank you for that.
5 MEMBER REMPE: Dave, I have a question too 6 on this building layout before you switch. Oh, Dave, 7 excuse me, I have a question about the reactor 8 building layout on the prior slide.
9 When I look at the CP application on saw 10 in Section 9.8.1 that they mentioned that there is 11 going to be a hot cells and a PIE and materials 12 testing laboratory facilities in the, could you tell 13 me where those are located? Are they in this 14 building?
15 MR. SONG: So currently the layout, it's 16 not -- so this is more preliminary based on the image 17 that is in the PSAR. That I don't think we actually 18 located that yet.
19 MEMBER REMPE: But it will be in this 20 building somewhere, is that a true statement? Or is 21 it going to be in a different building? Or are they 22 going to be in a different building?
23 MR. SONG: So, what was the system again?
24 Sorry, I --
25 MEMBER REMPE: Well, in Section 9.8.1 of 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
111 1 the PSAR it says that there is a hot cell, there is a 2 PIE and materials testing laboratory facilities. And 3 I was curious where they were all located.
4 They did say, I believe, that there was a 5 crane located, associated with them, and I was just 6 kind of curious where all of these facilities are. I 7 guess we can save the question till later, but I'm 8 just curious because, again, is there a potential you 9 could have any sort of radiation releases in the hot 10 cell facility.
11 How do you get stuff from the reactor to 12 the hot cell? I mean, there's a lot of those kind of 13 questions that we'll have to be thinking about as we 14 go through this review.
15 MR. KOSLOW: Yes, we'll double check the 16 words in the application and get back to you later in 17 the meeting.
18 MEMBER REMPE: Thank you.
19 MR. SONG: Thank you for the comment. So 20 the design considered is meteorological loads, such as 21 rain, snow, wind, tornado, and windblown missiles for 22 the site per local building code and NRC guidance for 23 the site.
24 The safety-related building is designed 25 without crediting the non-safety-related exterior 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
112 1 shell for protection from snow, wind, rain, and 2 missile loads. The exterior shell of the safety-3 related building is designed with a thickness to 4 protect the safety-related SSCs from high-wind 5 missiles, including debris from potential damage of 6 the non-safety-related reactor building.
7 Flooding loads. The safety-related 8 dumping will be protected from internal and external, 9 I'm sorry, internal flood with shields, curves and 10 drains, et cetera. Safety-related reactor venting 11 protects the safety-related SSCs from credible 12 external flood.
13 And the external envelopes uses water 14 tight flood protection features as well. There is 15 also isolator in the basement. However, the maximum 16 credible flood elevation is higher than that, but the 17 isolators will still perform with their function.
18 What's being provided.
19 So let's go to the next slide please. For 20 seismic loads we have been using risk-informed 21 performance based insights to determine the seismic 22 design criteria. For instance, ASCE 43-19 and we 23 define SDC 3 to be the criteria for the safety-related 24 SSCs.
25 The seismic design basis earthquake is 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
113 1 based on site specific seismic hazards considering 2 other recent nearby seismic hazard analysis. And site 3 specific geotechnical characteristics. And we will 4 confirm the data in the OOA.
5 The safety-related reactor building 6 incorporates spring dash pot (phonetic) seismic 7 isolation system, which lowers seismic demands of the 8 safety-related building and safety-related SSCs in 9 both horizontal and vertical directions.
10 And the moat wall and the flex connections 11 are considered to accommodate the displacements of the 12 isolated safety-related building. And also the -- and 13 the safety-related portion of the reactor building 14 will be represented by a three-dimensional FEA 15 developed in accordance with Chapter 3 of ASCE (audio 16 interference).
17 So that's -- I think that's --
18 MEMBER KIRCHNER: Another question, may I, 19 Dave? This is Walt.
20 Is the safety-related portion of the 21 reactor building also a functional containment or 22 confinement or does it --
23 MR. SONG: No, it's not. Yeah.
24 MEMBER KIRCHNER: So, where do you protect 25 it against leaks of Flibe in the system? At that 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
114 1 inner cavity is the place where you isolated?
2 For example, you showed isolation valves 3 on penetrations for the Flibe fluid lines. You show 4 a penetration for the pebble introduction and removal 5 systems. I didn't see isolation valves on that.
6 Where do you -- what do you try and 7 control any kind of fission product or Flibe leakage, 8 where is that done in terms of creating a "like a 9 confinement boundary" where you can control the 10 atmosphere because you're dealing with a toxic 11 material?
12 MR. HAGAMAN: This is Jordan Hagaman, 13 director of reliability engineering. In terms of 14 Flibe, the primary priority is to preserve enough 15 Flibe in the reactor vessel itself to maintain the 16 cooling function.
17 With regard to non-nuclear safety 18 considerations, we haven't discussed any of that in a 19 preliminary safety analysis report. And we're not 20 using the building for any physical confinement 21 functions for nuclear safety.
22 MR. GARDNER: So this is Darrell Gardner.
23 I would add one more thing there, that I think the 24 question you're asking really is more along the lines 25 of what we would consider contamination control, it's 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
115 1 not a confinement function.
2 MEMBER KIRCHNER: Okay. But it's a, let 3 me back off functional containment and just say 4 confinement. But some control, wouldn't your design 5 philosophy try and have a, how should I say it, a 6 barrier such that if you had fission product leakage 7 and/or leakage of Flibe, that you would have some 8 ventilation capability to have ventilation that would 9 be effective. It drives you to have kind of a minimal 10 leakage from that reactor building, right?
11 MR. GARDNER: Darrell Gardner again. Just 12 to reiterate, it would be from the contamination 13 control perspective, not from a dose consequence to 14 the public perspective.
15 MEMBER KIRCHNER: Okay.
16 MR. GARDNER: The Flibe is retaining the 17 fission product. It's --
18 MEMBER KIRCHNER: Yes. That's under 19 normal operation considerations. I'm just, I'm trying 20 to think of the fact --
21 CHAIRMAN PETTI: But the tritium --
22 MEMBER KIRCHNER: -- you have leakage the 23 tritium is going to come out.
24 CHAIRMAN PETTI: You've got ventilation, 25 right? And you've got a, what do you call it, traps 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
116 1 to, if there is any tritium in the vapor, in the 2 building.
3 MR. GARDNER: That's correct. There is a 4 non-safety HVAC system. That's why I said, this is 5 part of contamination control and effluent control, 6 it's not a dose consequence control.
7 MR. ZWEIBAUM: So before we move on, I did 8 want to circle back to Dr. Rempe's question about 9 Section 9.8.1. I did look at that section. And we do 10 say that that system is located in the reactor 11 building.
12 So like Brian said, the specific location 13 in the reactor building hasn't been nailed down, but 14 it is in the reactor building.
15 MEMBER REMPE: So thank you for that 16 clarification. I guess then I'm kind of thinking that 17 as part of a construction permit evaluation that it 18 would be behooves to know where it's located and how 19 material would come from the reactor in to some of 20 these facilities because that, I would think, would 21 fall under the purview of what we're thinking about 22 since you're pouring concrete to accommodate this and 23 we're supposed to understand the safety margin, I 24 believe, associated with some of these things.
25 And although we won't have all the 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
117 1 details, it seems like we need to know where it's 2 located. And there is a pathway that's adequately 3 protected. Does that seem reasonable to you?
4 MR. GARDNER: So, this is Darrell Gardner.
5 I'll speak to that quickly. Again, I think the kinds 6 of things that you're broaching over into is worker 7 protection and Part 20 requirements. Which are not 8 traditionally part of the PSAR.
9 We have addressed some bounding effluent 10 considerations, but as we note in the application, 11 those sort of details on things like shielding and 12 contamination control will all be addressed in the 13 FSAR.
14 MEMBER REMPE: Okay. Again, the Staff 15 will help decide this I guess too, but I'm thinking of 16 what we've seen in other construction permits we've 17 reviewed for other NPUFs in recent times. And we at 18 least kind of knew where the various rooms were 19 located in the building for some of the processes 20 involved. But we'll explore that further as we go 21 along in this review.
22 MR. GARDNER: Okay.
23 MR. CILLIERS: I'm going to go. Hi.
24 Thank you for the opportunity. This is Anthonie 25 Cilliers. I'm director for instrumentation controls 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
118 1 and electrical.
2 I'm going to start leading us into the 3 principles that we used to design the system and then 4 we'll move on to have a look at the architecture.
5 I'll also try and address some of the questions that 6 has come up before throughout the presentation, and 7 then we can have a further discussion.
8 Our I&C system is very much designed based 9 on the primary functions of the KP-FHR technology of 10 the reactor that we are designing. These include 11 features like a system so there is no depressurization 12 when you trip. And there's a large heat capacity in 13 the coolant. And pretty slow transients changes 14 inside the reactor itself. And of course, large 15 safety margin for the fuel integrity as well as for 16 the coolant. And these features are very important 17 for us when we were designing our reactor protection 18 system.
19 We have separated our I&C system into 20 various areas. First, we have our reactor protection 21 system. And they have been very deliberate to detect 22 an act on the fundamental metrics that might challenge 23 the integrity of the key system structures and 24 components.
25 And it relies on shutting down systems.
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
119 1 So it does rely on active power systems to shut it 2 down. So it relies basically on detect and shutdown 3 of various systems.
4 Then the next one we have is the plant 5 control systems, which is a non-safety-related system.
6 In this area this system relies of exhaust of hosts of 7 additional instruments throughout the plant. And that 8 is used to control plant operation, as well as early 9 detection of component failures to act on that before 10 we move into the safety space or any of the safety, 11 the SSCs integrity is challenged.
12 And we also have an intelligent health 13 monitoring system building. Again, non-safety-14 related, another safety-related system. This system 15 uses computational technics combined with 16 instrumentation data to detect component degradation 17 over time to assist us with operations and 18 maintenance. And also, keep us further away from 19 safety scenarios.
20 There has been questions about the 21 instruments specifically. Our instruments for the 22 plant, for the reactor protection system include 23 discrete level sensing in the core itself. That is an 24 in-house development process that we're going through 25 for custom detection working with the Flibe itself.
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
120 1 We will use thermal measurements in the 2 core. And again, we've been very deliberate in the 3 PSAR not to specifically talk about specific 4 technologies as we are evaluating various options in 5 these areas.
6 Neutron flux measurements as well is 7 inputs to the reactor protection system. At the 8 moment we are analyzing the exact location of them, so 9 you would have seen that some locations already 10 specify these locations to be specified.
11 But we have determined that our power 12 range detectors will most likely be outside of the 13 core. Almost definitely be outside of the core. So 14 is range detection is still, is still something that 15 we are finalizing.
16 And then we will also have indication for 17 a break in the pebble handling line, which is not 18 specified in the PSAR currently, but specific 19 measurement we'll be using there. But we have a 20 couple of different options that we are evaluating.
21 I think we can go to the next slide from 22 here.
23 MEMBER MARCH-LEUBA: Sorry.
24 MR. CILLIERS: Yes.
25 MEMBER MARCH-LEUBA: This is Jose again.
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
121 1 The use of ex-core detectors will be outside the core 2 but inside the vessel in the --
3 MR. CILLIERS: Outside the vessel.
4 Outside the vessel, yes.
5 MEMBER MARCH-LEUBA: Outside the vessel 6 where the DHRSs are?
7 MR. CILLIERS: Yes. Correct. It's with 8 the bioshield. Yes, likely in the bioshield area 9 outside of the vessel.
10 MEMBER MARCH-LEUBA: We still don't have 11 all the nomenclature of everything you call, but, so 12 it's not going to be in the reflectors it's going to 13 be outside --
14 MR. CILLIERS: It's not going to be in the 15 reflector, it's going to be outside the structure of 16 the vessel itself.
17 MEMBER MARCH-LEUBA: Very, very far away 18 from the core?
19 MR. CILLIERS: Yes. Yes. And the 20 temperature is also indicative of that, the 21 temperatures that those instruments will see. So it's 22 much lower temperatures that will be exposed to, 23 compared to what they will, that instruments inside 24 the core will see.
25 MEMBER MARCH-LEUBA: And this core has a 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
122 1 relatively low power auxiliary. Have you done some 2 estimates that you have sufficient signal to have to 3 drive the detectors?
4 MR. CILLIERS: Yes, that's correct.
5 That's where -- that's how we decide on the exact 6 location of these detectors.
7 Of course the source range detectors is a 8 little bit different because it also relies on the 9 size of the source itself and the location. But we 10 are very encouraging information there that they could 11 also probably be moved outside of the vessel itself.
12 CHAIRMAN PETTI: I'm glad you said that --
13 MR. CILLIERS: But the analysis --
14 CHAIRMAN PETTI: -- because I was going to 15 recommend that you look at that specifically. I think 16 in these small cores you could even put source range 17 stuff outside of the --
18 MR. CILLIERS: Yes.
19 CHAIRMAN PETTI: -- reactor which would 20 simplify a lot of things.
21 MR. CILLIERS: That's correct. So yes, we 22 will plan that out once we have more information on 23 the analysis from our mod safety (phonetic).
24 MEMBER MARCH-LEUBA: And this is Jose 25 again.
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
123 1 MR. CILLIERS: Yes.
2 MEMBER MARCH-LEUBA: On the cartoons 3 earlier we saw only three detectors for both level and 4 power.
5 MR. CILLIERS: Yes.
6 MEMBER MARCH-LEUBA: Have you decided that 7 you're only going to have three protection channels?
8 MR. CILLIERS: No. At the moment we are 9 deciding between two and three. You will see in the 10 Chapter 7 of PSAR we always expect four channels. So 11 most likely we will move them outside to have four of 12 them.
13 We are planning to have neutron flux 14 mapping inside the core. And those will not be 15 safety-related instruments that may use only the three 16 detectors.
17 MEMBER MARCH-LEUBA: Those are equivalent 18 to the SPDMs or the LPRMs in BWRs?
19 (Simultaneously speaking.)
20 MR. CILLIERS: The flux mapping.
21 MEMBER MARCH-LEUBA: Flux mapping. In 22 BWRs they're called LOCA power range monitors.
23 MS. CROWDER: Yes.
24 MEMBER MARCH-LEUBA: In PWRs they're 25 called SPDMs.
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
124 1 MR. CILLIERS: Yes. So, yes, that's for 2 flux mapping to determine what the flux shape is 3 inside the core.
4 MEMBER MARCH-LEUBA: Okay. Okay.
5 MEMBER BROWN: Can you back a slide?
6 MR. CILLIERS: Can I continue?
7 MEMBER BROWN: Yes. What do you mean a --
8 MR. CILLIERS: Okay, next slide.
9 MEMBER BROWN: No, no, no, no.
10 MR. CILLIERS: Oh, sorry.
11 MEMBER BROWN: Go back to --
12 MR. CILLIERS: Okay, I'm sorry.
13 MEMBER BROWN: What do you mean by semi-14 autonomous control room?
15 MR. CILLIERS: Oh, I apologize, I should 16 have continued there. So our control room does not 17 have any, we do not create any safety functions by 18 operators. So the control room itself acts as a view 19 into the reactor and into the plant itself.
20 So the operators are operating the plant 21 under normal operational conditions. But it does --
22 and some of the functions of operations is automated.
23 But the reactor protection system acts 24 completely separate from the control room itself. So 25 we are moving away from the relying on operator 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
125 1 actions for safety functions.
2 MEMBER MARCH-LEUBA: So what you're saying 3 is that the operators are not relied upon for any 4 safety function?
5 MR. CILLIERS: None at all.
6 MEMBER MARCH-LEUBA: And can you --
7 MR. CILLIERS: In the same way we would --
8 (Simultaneously speaking.)
9 MR. CILLIERS: Yes, go on.
10 MEMBER MARCH-LEUBA: Yes. Yes, then you 11 would have to worry about the force inside the core.
12 Anything the operator can do to make it go bad.
13 I mean, there are errors of omission and 14 errors of commission. Have you considered those?
15 MR. CILLIERS: Sorry, you have to repeat 16 that, I --
17 MEMBER MARCH-LEUBA: There are some things 18 called errors of omission when the operator doesn't do 19 something. And then this error of commission where 20 the operator does the wrong thing.
21 MR. CILLIERS: Yes. I will explain in the 22 next slide what the principles are of that.
23 MEMBER MARCH-LEUBA: Okay.
24 MR. CILLIERS: And then of course on the 25 electrical --
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
126 1 MEMBER REMPE: Excuse me. Are you 2 planning to have the operators licensed by the NRC?
3 MR. CILLIERS: At this stage we are 4 considering that, but we have to consider what is 5 actually the functions of the operators to have them 6 licensed. But yes, we are working through how they 7 will be licensed.
8 MEMBER REMPE: Thank you.
9 MR. CILLIERS: Then the last point there 10 on the electrical supply system, we'll have a slide on 11 that architecture. It's important to say that we, to 12 state that we do not have safety-related electrical 13 supply because we do not rely on the electrical supply 14 for any safety functions. And so that's outside of 15 the safety-related scope as well.
16 MEMBER MARCH-LEUBA: Are you planning to 17 have battery backup for monitoring?
18 MR. CILLIERS: We do have batter backup.
19 And I'll show that when we get to the layout of the --
20 MEMBER MARCH-LEUBA: Okay. I'll wait 21 then.
22 MR. CILLIERS: -- electrical system as 23 well. Although it's on safety-related.
24 So here is a little bit of a, the 25 principles that we have. As I mentioned, we are very 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
127 1 deliberate in the fundamental matrix of what we want 2 to measure for the reactor protection system so that 3 we can predict the integrity of the system itself.
4 You'll see on the left-hand side that's a 5 depiction of a operating envelope. The blue area is 6 the pump control system. And that is where the 7 operators is acting within.
8 And that brings us to the point where the 9 question came from the omission of operators or the 10 operators deliberately or by accident doing something 11 incorrectly. As long as the operations, both 12 operational parameters remain inside that blue, the 13 light blue area, the reactor protection system does 14 not intervene and the operators can actually operate 15 and make mistakes if that should happen without 16 challenging the integrity of the system itself.
17 Once it crosses the boundary into the red 18 space, the reactor protection system, those very 19 specific measurements, metrics will determine that the 20 plant is now in a space where it could challenge the 21 plant integrity. And automatically the reactor 22 protection system will intervene and shut the reactor 23 down.
24 At the same time it will also block all 25 operations coming from the plant control systems. So 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
128 1 it will take over complete control of the system. And 2 I will show you in the architecture how that is done.
3 Now, you'll see on the right-hand side 4 there is a graph of the different temperatures that 5 we're looking at and different instruments and that 6 will operate in specific ranges.
7 An important point to take away there is 8 our fuel integrity is 1,600 degrees. It's a very, 9 very high temperature, and we're staying far away from 10 that. Flood boiling point temperature is 1,430 11 degrees. Again, very far away from that. As well as 12 the vessel integrity, which is 850 degrees.
13 So our whole analysis of early detection 14 of operations that could challenge that revolves 15 around staying far away from that temperature as well.
16 And so we'll be operating in the range below 700, 705 17 and above 460 degrees.
18 And the real principle of the operating 19 system, of the plant control system is to maintain our 20 operating parameters in that blue boundary. And if it 21 crosses over at any time that's where we will check 22 the reactor. Any questions on that?
23 MEMBER BROWN: Yes.
24 MEMBER REMPE: Yes. Go ahead, Charlie.
25 MEMBER BROWN: Basic reactivity control 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
129 1 and plant condition control, is that done by the 2 operator?
3 MR. CILLIERS: Yes. That can be done by 4 the operator inside the blue space.
5 MEMBER BROWN: I heard you use, you said 6 can be.
7 MR. CILLIERS: Well they can be. The 8 plant control system will be automated to maintain 9 that at certain levels. But the operator will be able 10 to control the reactivity inside the blue space. Yes.
11 MEMBER BROWN: So, startups are done 12 automatically. You punch a button, the plant starts 13 up and everybody goes to sleep, is that the way they 14 envisioned it?
15 MR. CILLIERS: No, that's not the way we 16 envisioned it.
17 (Laughter.)
18 MEMBER BROWN: I'm being --
19 MR. CILLIERS: We will have a step-by-step 20 approach to get the plant up to temperature. And as 21 soon as we are in the blue space, then the operators 22 will be able to operate it. When the plant is heated 23 up and we can go to criticality.
24 MEMBER BROWN: Is the plant operating 25 condition maintained automatically without any 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
130 1 operator input? That's all I'm saying. Once you get 2 into the blue space --
3 MR. CILLIERS: Yes.
4 MEMBER BROWN: -- is it hands off?
5 MR. CILLIERS: Not in the blue space. In 6 the blue space the plant conditions will be 7 automatically controlled. But the operators can 8 change those conditions. As long as they remain 9 within the blue space.
10 CHAIRMAN PETTI: But they don't have to, 11 right?
12 MR. CILLIERS: They don't have to, no.
13 CHAIRMAN PETTI: Okay.
14 MR. CILLIERS: We could change modes.
15 There is a number of modes that it can move into. But 16 the operators, as long as they're in the blue space 17 the operators do have autonomy to be able to make 18 decisions in that space.
19 And it's important to note, once they get 20 into the red space the operators do not have any 21 control over what, to change any of those parameters.
22 And I'll explain that. I have a couple of examples in 23 the next slide.
24 MEMBER REMPE: So maybe you're planning to 25 mention this in the next few slides, but in Table 7.2-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
131 1 1 it lists some control parameters. And I just was 2 curious why the coolant level isn't listed as a 3 control parameter?
4 MR. CILLIERS: The coolant level within 5 the vessel itself?
6 MEMBER REMPE: Right. Because it seems to 7 me, again, you want to keep that coolant above the 8 core for natural circulation, as well as for fission 9 product retention.
10 MR. CILLIERS: Right. I will have to have 11 a look at that. I think, I believe the coolant level 12 is maintained through the syphon system, as well as 13 our full drain system. And then of course we've got 14 the trips on low and high level of the coolant. But 15 I will have to have a look, because I think -
16 MEMBER REMPE: Okay. Maybe I missed some 17 things too because it seems like it ought to be there.
18 Thank you.
19 MR. CILLIERS: Yes. Okay. So the next 20 slide you see, this is our architecture. And you see 21 in the PSAR as well.
22 You can see the separation between the 23 blue areas, which is non-safety, and the red areas, 24 which is the safety system. It's really important to 25 note that they are absolutely isolated from one 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
132 1 another. And this is achieved in two ways.
2 The reactor protection system in red 3 communications information out through a one-way, we 4 call it a data diode. But the reality is, there is 5 only one-way communication out of the reactor 6 protection system. It does not have hardware that can 7 take signals from the outside.
8 So it's a one-way communication to the 9 operators so that they can see what the indications 10 inside the reactor protection system. The reactor 11 protection system knows about itself and the 12 indications that it's getting from the reactor, which 13 I mentioned before includes the discrete level 14 indication, temperature indication, neutron detection, 15 as well as the DHRS line break. Those indications are 16 used for trips.
17 There is another output from the reactor 18 protection system, which is a slightly different one 19 from normal trips. And that is the DHRS activation.
20 And I think Nico explained some of that earlier on.
21 And what happens with DHRS is, once we've 22 reached a certain power level or accumulated a certain 23 level of fission products in the core, based on the 24 count of the neutron detectors the DHRS will be 25 activated by the reactor protection system 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
133 1 automatically and it will be locked so that the 2 operators are unable to deactivate it.
3 After shutdown, should a shutdown occur, 4 if the temperature is, goes low enough, that the 5 reactor protection system will then release that lock 6 so that the DHRS can be deactivated. But although it 7 won't be deactivated automatically. It will just 8 allow deactivation. So that's a spatial nuance to 9 what the reactor protection system does.
10 As for the rest, the reactor protection 11 system, it measures level temperature flux. And based 12 on that it activates the RCCS control safety elements 13 that will drop into the reflector, into the core based 14 on their design using gravity. So it actually removes 15 power from the system to drop those rods.
16 It also removes power from all the active 17 systems that the plant control system is operating.
18 That includes the primary salt pump, the PHSS, the 19 pebble handling system, as well as the other flood 20 coolant systems.
21 It's very much designed around using the 22 DHRS as our active cooling system. Having said that, 23 this is when we reach that great levels in the 24 operating envelop, the plant control system in the 25 blue space has got access to a whole host of 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
134 1 instruments.
2 And should anything, any failure be 3 detected through those instruments, the plant is also, 4 can also be shut down, or power can be reduced as 5 necessary, long before we reach the level where the 6 reactor protection system is required to intervene.
7 Any questions on that?
8 MEMBER BROWN: Absolutely. I notice in 9 your diagram that all your main plant control systems, 10 all your non-safety control systems, are directly 11 connected to the internet, through gateways and 12 ethernet connections. So a hacker can come in and 13 turn your plant upside down.
14 MR. CILLIERS: That is a really good 15 question. We talk about that quite a lot. It is --
16 we are all feeding information -- or the plant will be 17 feeding information to our support systems outside.
18 We rely heavily on the required cybersecurity features 19 that we're building in, but the same scenario, if you 20 go one slide back maybe, the -- as long as you stay in 21 the blue side, the blue space, the reactor cannot be 22 turned upside down. The reactor protection system 23 will always intervene if something like that should 24 happen.
25 Go on to the next slide. And you can see 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
135 1 there that the rate system is not connected to any 2 part of the outside world whatsoever. That being 3 said, we are not taking cybersecurity lightly, and 4 implementing all the needed cybersecurity 5 implementations of making sure that -- yes?
6 MEMBER BROWN: You could make it really 7 clear if you take that cloud away and don't put 8 anything in there. You can assess that issue when you 9 get down to the details.
10 MR. CILLIERS: Yes.
11 MEMBER BROWN: Very heavily detailed.
12 That is -- I probably shouldn't say anything, but to 13 me, that's totally unacceptable. I'm just passing on 14 one member's conclusion from reading this.
15 MR. CILLIERS: So noted. Thank you.
16 Next slide. Okay, I think this is a bit 17 of animation, so you can go to the first animation.
18 MEMBER BROWN: Can I give you one other 19 observation before you go on?
20 MR. CILLIERS: Sure.
21 MEMBER BROWN: You can go to -- is this 22 the picture, the next slide?
23 MR. CILLIERS: That's the next slide, it 24 should show pretty much the same system.
25 MEMBER BROWN: Yeah, well, you have -- the 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
136 1 one I've got, Slide 39, shows pictures of operators 2 sitting at screens.
3 MR. CILLIERS: Yes, that's coming up. So 4 that's the animation.
5 So, okay, just to give you an example of 6 the path that we are going through, with our 7 engineering test unit, we are actually building all of 8 these systems and testing them with all the features 9 that we require.
10 So the first animation, that is our flood 11 control system. That is actually being tested right 12 now. That includes controls of the primary salt pump 13 and various others, so basically all the non-safety 14 features.
15 Next slide.
16 MEMBER BROWN: So they're all integrated?
17 MR. CILLIERS: At the moment, they're all 18 integrated, yes.
19 MEMBER BROWN: So one or two processes 20 integrate all the plant-controlled functions into 21 those areas, totally? Even though they're non-safety-22 related, you've totally integrated that system? So if 23 a box goes up in flames, you're toast?
24 MR. CILLIERS: Yes, but for the reactor 25 system as well, that we will not integrate it in that 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
137 1 way. So the functions are separate, but they run on 2 a single box.
3 MEMBER BROWN: I saw that in your non-4 animation. Go ahead.
5 MR. CILLIERS: Okay. So, at the bottom 6 you can see our instrumentation test unit. That's 7 where we are testing all our salt-wetted instruments 8 at temperature and that's being conducted right now.
9 Next slide. The next one. That is our 10 remote support room where we are sourcing data through 11 -- from the control system where -- that's located in 12 our headquarters here in Albuquerque and that's 13 supporting for the engineers to support the operations 14 of the system.
15 Next slide. That's our project control 16 room that's in Albuquerque, New Mexico, where we are 17 developing the human-machine interfaces for the system 18 itself, as well as connecting that to the simulators 19 to test all our operations.
20 Next one. This is a couple -- just a 21 picture of the different instruments that we are 22 actually implementing in our engineering test unit.
23 You can see the little green one at the bottom right 24 corner. That is our in-house-developed level switch, 25 which uses two probes that, when the Flibe touches the 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
138 1 two probes, it indicates a level indication. So it 2 operates really fast and it's custom made for the 3 Flibe application specifically.
4 Next slide. We've developed a simulator 5 model that incorporates, at the moment, all the 6 thermal-hydraulic aspects of the system. And it's 7 connected directly to the HMI that we are developing 8 for the operators to use. And this will be used for 9 operator training, as well, as we move on. It will 10 also be expanded to include the neutronics processes 11 as well.
12 The last one. That is our reactor 13 protection system. We are using the HIPS platform 14 that is the license platform by Rock Creek Innovations 15 and we are testing that out as well with all the 16 safety indications. And as I said it's already 17 completely separate from all the other systems.
18 MEMBER BROWN: Are you using the HIPS 19 system right out of the HIPS topical report?
20 MR. CILLIERS: At the moment, yes. We're 21 not making changes from the --
22 MEMBER BROWN: With the volatile/non-23 volatile processors or FTGAs. Okay.
24 (Simultaneous speaking.)
25 MEMBER MARCH-LEUBA: Yes, this is Jose.
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
139 1 On the topic picture, I see five work stations in the 2 control room. You don't really expect five operators 3 per reactor, do you?
4 MR. CILLIERS: No, not at all. This is 5 for development purposes. We are most likely going 6 down to three, so the three seats in the front is the 7 operator screens and the two in the back are 8 instructor screens for operation.
9 MEMBER MARCH-LEUBA: And it looks like a 10 control room for operating a reactor for a light-water 11 reactor, right? I would have expected you to be 12 shooting for one operator at most.
13 MR. CILLIERS: We are using iterative 14 development. As we learn more, we will implement 15 those type of reductions.
16 MEMBER MARCH-LEUBA: And that again will 17 be maybe accomplished at the operating license step?
18 MR. CILLIERS: Yes.
19 MEMBER MARCH-LEUBA: We have no idea now.
20 Okay.
21 MR. CILLIERS: Next slide. I think this 22 is the last slide. So this is the indication of our 23 electrical architecture. Our electrical architecture 24 in the PSAR is currently limited to the I level 25 electrical supplies. We don't exactly know all of 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
140 1 those blocks what the exact power demands would be and 2 the voltages required for each different one.
3 Important, yes, is I think the question that came 4 earlier, you will see there is uninterruptable --
5 uninterrupted power supplies supplied to various 6 systems such as the plant control system, the reactor 7 protection system, the main control room.
8 All of those have got 72-hour 9 uninterrupted power supply capacity. Should we lose 10 complete power, although we do have normal power 11 supply coming in from a feeder from the utility, as 12 well as backup generators with automatic transfers 13 switching between our normal to backup supply, that 14 automated transfer switch is specified to transfer 15 power within 20 seconds from the normal supply to the 16 backup supply. And for that reason we have a small, 17 short duration capacity to prevent interruption during 18 the transfer, so that the systems that require power 19 do not trip. This is important. They require power 20 to not trip, will not trip during a transfer such as 21 that.
22 If the transfer fails, that 10 to 20 23 seconds lapses and then they will trip, so the plant 24 will trip without power if they don't have normal, 25 backup power supply.
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
141 1 MEMBER BROWN: You said a time. You said 2 20 seconds?
3 MR. CILLIERS: Yes, that's correct.
4 MEMBER BROWN: So you're going to have 5 enough built-in capacity in whatever systems, they'll 6 hold up during that open period?
7 MR. CILLIERS: Yes. It's a very small 8 power supply that's required. They just keep the 9 relays open.
10 MEMBER BROWN: So you get the backup --
11 MR. CILLIERS: Until the backup is 12 running, that's correct, yes.
13 And that's an important point to raise.
14 This is for the safety-related system, but it gives 15 you a better idea of what the architecture looks like 16 to supply the system so that you can monitor for 72 17 hours1.967593e-4 days <br />0.00472 hours <br />2.810847e-5 weeks <br />6.4685e-6 months <br /> after complete loss of power, although in most 18 cases our backup for normal power supply will be 19 available.
20 I think that was the last slide. Any 21 questions?
22 MEMBER BROWN: There will be more. This 23 is just an overview, right?
24 MR. CILLIERS: Of course.
25 CHAIRMAN PETTI: This is the end of the --
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
142 1 let's just call it the hardware discussion. And then 2 we're going to transition to safety cases?
3 MR. CILLIERS: Yes.
4 CHAIRMAN PETTI: Maybe this is the right 5 time to take a break then.
6 MEMBER BROWN: Good idea.
7 CHAIRMAN PETTI: So let's come back at 10 8 after the hour.
9 (Whereupon, the above-entitled matter went 10 off the record at 3:51 p.m. and resumed at 4:10 p.m.)
11 CHAIRMAN PETTI: Okay, it's ten after.
12 Kairos, are you ready to continue?
13 MR. PEEBLES: One second. We're pulling 14 up the slides.
15 All right, so last up is Jordan with the 16 safety case.
17 MR. HAGAMAN: All right, good afternoon.
18 My name is Jordan Hagaman. My role is Director of 19 Reliability Engineering at Kairos Power and in the 20 next few slides we'll be discussing the approach to 21 demonstrating margins for nuclear safety for the 22 Hermes construction permit design. I'll explain the 23 approach and the strategy to the design of the safety 24 case, but we're going to rely on other subject matter 25 experts at Kairos to address discipline-specific 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
143 1 questions.
2 The safety case for the Hermes reactor is 3 described in Chapter 13. First, it's important to 4 understand the overall design of the safety case 5 (audio interference) accident and its relationship to 6 other postulated events.
7 Coming up, we'll talk about specific 8 events in the safety case and further discuss the MHA 9 analysis itself as well as the approach to analyzing 10 the consequences of postulated events.
11 The focal point of the safety case is the 12 maximum hypothetical accident analysis which is 13 presented as a bounding demonstration of margins to 14 the dose limits in Part 100 siting criteria.
15 The MHA is specifically designed to be 16 bounding in a non-physical way which means it's 17 decoupled from many of the specific design details of 18 the future Hermes plant. This should give confidence 19 that the MHA analysis results and conclusions remain 20 consistent over time as the Kairos teams learn from 21 non-nuclear hardware demonstrations and make perfected 22 changes to the Hermes design before it's built.
23 As we'll discuss, the design of the MHA 24 has built in conservatisms that stress the components 25 of the Hermes' functional containment to overestimate 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
144 1 the postulated release of radionuclide material in the 2 source term.
3 The maximum hypothetical accident by 4 design bounds the consequences of all postulated 5 events considered for the Hermes safety case. We'll 6 get to the list of postulated events next.
7 The list of postulated event groups is 8 comprehensive such that the consequences of any 9 postulated initiating event are bounded by the 10 limiting case in one of those groups or the strategy 11 to preclude or prevent that initiator is described and 12 that's also in Chapter 13.
13 Although the MHA assumptions are largely 14 decoupled from the design features of the to be built 15 Hermes, the postulated event analyses will be more 16 dependent on the final design. Because of this, the 17 preliminary safety analysis at the construction permit 18 stage focuses on qualitative descriptions of how the 19 transients will be bounded by the performance of the 20 plant.
21 The detailed, quantitative results of 22 safety analysis for the postulated events will provide 23 the final demonstration that the consequences of all 24 of the PEs are bounded by the consequences of the MHA.
25 All of that information will be available in support 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
145 1 of the operating license application itself.
2 To get confidence at the construction 3 permit stage that the final safety analysis is 4 achievable, acceptance criteria are provided that 5 define figures of merit specific to each postulated 6 event group. These criteria are specifically defined 7 as surrogates that will be used to demonstrate that 8 the bounding case for each event group is bounded by 9 the MHA analysis.
10 To begin -- take that to the next slide.
11 As introduced earlier, the MHA is the 12 centerpiece of the Hermes safety case and the MHA is 13 the tool used to quantify margins of safety in the 14 preliminary Safety Analysis Report.
15 We'll discuss the actual assumptions and 16 margins for the MHA in the next slide. The other 17 seven groups are postulated events that will be 18 demonstrated to be bounded by the MHA. In each of 19 these events, the reactor protection system which we 20 just heard about in the last presentation is available 21 to remove power from key systems to initiate trips of 22 the RCSS, the primary pump, the pebble extraction 23 machine. And passive decay heat removal is available 24 to bring the Hermes reactor to a safe state without 25 recourse to operator actions.
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
146 1 In each event group, the analysis will 2 leverage the high-thermal margins of the TRISO fuel 3 and of the salt coolant to demonstrate mitigation of 4 radionuclide release consequences to lessen those from 5 the MHA.
6 So I'll describe each event class at a 7 high level and we can come back to it if there's any 8 questions about the strategy for any of these.
9 CHAIRMAN PETTI: So Jordan, I had a 10 question. If you've seen anything that we've written 11 on the concept of figuring out what events to look at, 12 we talk about starting with a clean sheet of paper and 13 rarely thinking hard about this.
14 How much of what you did, did you look at 15 other reactor types? Because, you know, this is a 16 unique one. It's neither feast nor foul or whatever 17 that expression is.
18 For instance, you know, there are a number 19 of fast reactor transients that are out there that one 20 could think about for a system like this. There's a 21 number of pebble bed transients or gas reactor 22 transients that have been done on every small gas 23 reactor that's ever been built in the world.
24 Did you look at, you know, those sorts of 25 events to come up with a list? Because specifically, 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
147 1 I don't see a lot in the unprotected event category.
2 And again, not arguing, per se, one should say a fully 3 unprotected event, but even a delayed reactivity 4 event.
5 My perspective here is you guys have an 6 amazingly robust technology because you're marrying 7 two really good technologies, TRISO fuel and salt.
8 And you can be bold in some of these events and show 9 how the inherent features of those two technologies 10 keep the design safe, even in some pretty severe 11 events, more severe than what you've looked at. And 12 yet, you haven't done that.
13 I just personally think that, from a 14 public safety perspective, that would be a very good 15 position, given you guys have really the first 16 advanced non-LWR to come into the system, that you 17 would be able to demonstrate very robustly with events 18 that even are a little bit more severe than what 19 you've considered.
20 MR. HAGAMAN: Thank you for that comment.
21 What we're trying to do with the first nuclear 22 demonstration hardware at Kairos is we're trying to 23 develop a safety analysis that can largely bound a lot 24 of the detailed trade space right now which means that 25 we're trying to decouple the safety analysis from a 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
148 1 lot of specific design considerations and further, 2 we're working on a pathway to demonstrate all of our 3 methods. And I believe at this point, it would be too 4 much of a step in one iteration trying to go all the 5 way to, for example, using inherent reactivity 6 feedback to reduce power without shutdown elements.
7 Right now, we think that it's an easier 8 step to credit reactivity shutdown via shutdown 9 elements rather than inherent reactivity feedback and 10 things like that, so we -- we're not looking to be too 11 aggressive with all of our margin at this point with 12 our very first reactor.
13 Is that addressing your question?
14 CHAIRMAN PETTI: I understood that. I was 15 thinking, as I read it, well, maybe you guys plan on 16 doing some transient testing in the reactor, like EBR2 17 did, or like the small gas reactors did. But then I'm 18 worried that, in a four-year life, you've got an awful 19 lot to do in four years. Those tests take a little 20 bit of time to think about.
21 Are you still even thinking about those 22 sorts of things because they could so well inform the 23 larger one, you know, you're planning the commercial 24 one when you're planning down the road.
25 MR. HAGAMAN: So I don't think that I have 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
149 1 more to offer at this time on whether or not we would 2 be considering that.
3 CHAIRMAN PETTI: Just a member's comment.
4 Something to think about.
5 MR. HAGAMAN: Okay.
6 CHAIRMAN PETTI: Because you guys, 7 probably most of you guys weren't even around in those 8 days. I was here when EBI2 was done in Idaho. I mean 9 it was on the front page of the papers. It made a big 10 impact about the safety of the technology and so it's 11 just something to consider.
12 MR. HAGAMAN: That's a good comment, but 13 at this point we don't have anything in chapter --
14 (Simultaneous speaking.)
15 CHAIRMAN PETTI: Right, I saw that.
16 MEMBER REMPE: So this is Joy, and I have 17 a question that is just general. Could you explain to 18 us how you track all the assumptions for, which data 19 don't yet exist, that you used in these analyses? And 20 is there some system that the staff can audit that 21 shows all of these assumptions? And if that list 22 exists, you also have a comment after then that says 23 we're planning to get this data in such and such a 24 facility?
25 MR. PEEBLES: So, just at a high level, 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
150 1 to answer your question, this is Drew Peebles. We do 2 have something that is available to the staff to 3 audit. And there is kind of an audit open on Chapter 4 13. I won't get ahead of the staff on their review, 5 but yes, the answer to your question is that 6 information is available to the staff.
7 MEMBER REMPE: And so just generally has 8 the staff been -- maybe they haven't finished the 9 review enough, but if a list does exist so they can 10 audit it, do they sometimes in some of the 11 interactions that are ongoing they've identified 12 additional assumptions that -- I mean, is this back 13 and forth yet? Or you haven't gotten that far in the 14 process with the RAIs?
15 MR. PEEBLES: Yeah, I think I better 16 answer those questions after the review is completed.
17 We're still in audit discussions right now.
18 MEMBER REMPE: Okay. Thank you.
19 MR. HAGAMAN: So I was prepared to just 20 speak briefly about what is grouped in each of these 21 postulated event groups for awareness. As a reminder, 22 these are all of the groups that we are, by design, 23 are making sure that our maximum hypothetical accident 24 analysis bounds.
25 So where the MHA is our tool to 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
151 1 demonstrate margins, these other events, we come up 2 with other methods to show that they are bounded by 3 the MHA and therefore have at least the margin that 4 the MHA demonstrates.
5 So the first group is insertion of access 6 reactivity. This is a group of events that includes 7 reactivity and insertion of events ranging from fuel 8 loading errors to increase in heat removal events and 9 overcooling to phenomena associated with shifting 10 reactor blocks or movement of gas bubbles.
11 The salt spill events involve a loss of 12 primary coolant from the primary heat transport 13 system. I want to note here that the preliminary 14 Safety Analysis Report deliberately describes events 15 as salt spills and not loss of coolant accidents. We 16 do this to avoid confusing the phenomenology of light-17 water reactor LOCAs with the phenomenology of the 18 Hermes reactor where coolant spills have significantly 19 less safety significance.
20 MEMBER MARCH-LEUBA: Let's just stop 21 there. Let's stop there. A salt spill is not called 22 a LOCA. What happens if you spill enough salt that 23 you uncover the return path so that your natural 24 circulation doesn't work anymore. Again, a LOCA of 25 the return line that goes to the feedwater, I mean the 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
152 1 one that goes to the heat exchanger, if that line 2 breaks down, everything drains through it, not only 3 drain through it, you stop the natural circulation and 4 you have a path out to the vessel for all the --
5 MR. HAGAMAN: I understand. The salt 6 spill, we look at the entire spectrum of locations and 7 sizes for leaks including on the cold leg and we have 8 features built into the vessel to break the siphon 9 should a leak in the cold leg happen. So the siphon 10 breaking --
11 MEMBER MARCH-LEUBA: How about breaking 12 the hot leg?
13 MR. HAGAMAN: I'm sorry, can you repeat 14 the question?
15 MEMBER MARCH-LEUBA: How about breaking 16 the hot leg?
17 MR. HAGAMAN: Hot leg as well. The 18 features are actually built into -- I want to make 19 sure I get the terminology correctly, the pump casing 20 itself, I believe, to break the siphon.
21 MEMBER MARCH-LEUBA: So the hot leg is 22 pumped from the pump from the top of the vessel?
23 MR. HAGAMAN: Correct.
24 MEMBER MARCH-LEUBA: What I'm looking for 25 is a possibility of draining the vessel, having a salt 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
153 1 spill, either through a LOCA or through an inadvertent 2 action of something that will lower the level below 3 and not the circulation.
4 MR. HAGAMAN: So I have a team of people 5 that is also looking for that scenario and we are 6 looking for the list of assumptions where we can say 7 that that is precluded. So we've done a lot of work 8 in that area. The anti-siphon features, limitations 9 on gas entrainment, as well as the trip timing for the 10 pump are all -- and the elevation of penetrations are 11 all part of the series of design characteristics that 12 we're going to be relying on to preclude that event.
13 MEMBER MARCH-LEUBA: So they will -- you 14 promised, I think you promised there will be design 15 features that will prevent this, but they don't exist 16 now?
17 MR. HAGAMAN: So Chapter 13 describes what 18 we call the list of prevented events. This is part of 19 the uncooled event where, for whatever reason, we look 20 for all of the ways that we could lose capability to 21 remove to decay through our DHRS system. And that is 22 one of the areas where we're identifying the design 23 features. We've done that at a high level in the 24 preliminary Safety Analysis Report. And what you can 25 expect is as part of the application for an operating 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
154 1 license, we will have all of the features and controls 2 that include both design features and programmatic 3 operational features to ensure that this event stays 4 precluded through the life of the plant.
5 MR. PEEBLES: This is Drew Peebles. I 6 have to add that this isn't a pinky promise that this 7 is going to happen at the OLA (phonetic). We have 8 hard commitments in the PSAR that we will maintain the 9 Flibe level above the active core for both normal 10 operations and all postulated events. But there is no 11 spill that we've identified that could drain the Flibe 12 below the top level of the active core.
13 MR. GARDNER: This is Darrell Gardner. I 14 would also add that currently in the PSAR, for any 15 penetration into the vessel, we have already describe 16 how we address, functionally, any seismic scenarios.
17 So if you go and look, for example, Chapter 9 for 18 systems that connect to the vessel, or if you look in 19 Chapter 5, which is the inlet and outlet PHCS lines, 20 that's already discussed.
21 MEMBER MARCH-LEUBA: I'm looking forward 22 to looking through all of that. I'm looking at 23 Chapter 15 -- 13 and it's very light on details.
24 MR. PEEBLES: So those are event analyses, 25 but again, in the system design you will see the 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
155 1 discussions of the design features to preclude drain 2 down events.
3 MEMBER MARCH-LEUBA: I don't see anywhere 4 saying -- I mean you always say keeping the core 5 covered. What you need to say is keeping the natural 6 circulation path covered.
7 MR. PEEBLES: That's also in Chapter 4.
8 Chapter 4 has commitments for both natural circulation 9 and keeping the core covered.
10 MEMBER MARCH-LEUBA: We'll look at it in 11 more detail when we review chapter by chapter. Right 12 now, I don't have much hard feeling that everything is 13 -- I think if you start with assumptions that 14 everything is super safe and work backwards, that's 15 the impression I'm getting.
16 MEMBER REMPE: It does seem like the welds 17 holding the bottom plate of the vessel to the cylinder 18 are going to be very robust to never fail.
19 MR. PEEBLES: Yes, but that's not 20 dissimilar than the light-water reactor vessels.
21 MEMBER REMPE: There are hemispheres and 22 they're welded to different locations other than a 23 flat plate. I'm just kind of thinking about it. I 24 don't have an opinion yet. I'm just exploring it.
25 CHAIRMAN PETTI: Keep on going, Jordan.
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
156 1 MR. HAGAMAN: All right, so as discussed, 2 salt spills include the spectrum of leak sizes and 3 locations throughout the non-safety-related primary 4 coolant system where we leave off. The loss of forced 5 circulation is an event group that includes a range of 6 events from mechanical or electronic failures of the 7 primary pump during operation to flow blockages in the 8 primary coolant system, all the way to just normal 9 loss of -- normal heat sink events or even a loss of 10 power. Those are all grouped under loss of forced 11 circulation.
12 The mishandling or malfunction of pebble 13 handling in storage systems, this is a group of events 14 that includes pebble transfer line breaks for lines 15 that bring the pebbles into the empty core or the at-16 power core, all the way to the lines transferring 17 pebbles to storage containers. So we look at the 18 potential for malfunctions or breaks in all of the 19 lines there.
20 The radioactive release from a subsystem 21 or component. This is a standard category from NUREG-22 1537 for an FHR. For Hermes, it includes faults in 23 the tritium management system, the inert gas system, 24 chemistry control, inventory management.
25 General challenges to normal operation 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
157 1 includes spurious control system trips, inadvertent 2 operator actions. There's a suite of possible events 3 that you could expect inside of what Anthony in the 4 last presentation showed as his blue box. All of 5 these events we expect to be bounded by the worst 6 event and the loss of forced circulation.
7 And the internal and external hazard 8 events, this largely goes back to Chapter 2 of the 9 preliminary Safety Analysis Report in Brian Song's 10 presentation from earlier today where internal fire, 11 internal and external floods, seismic, high winds are 12 all evaluated against their potential to interrupt the 13 function of safety-related SSEs. We build that into 14 the design basis.
15 So we're ready to jump into the slide 16 about the maximum hypothetical accident. So in order 17 to demonstrate in the construction permit application 18 that the Hermes maximum hypothetical accident is, in 19 fact, a sufficiently conservative hypothetical event, 20 the PSAR points out specific, non-physical assumptions 21 that are meant to challenge the elements of functional 22 containment, namely, that's to drive the fusion of 23 radionuclides through TRISO layers and to increase the 24 evaporation of radionuclides from the free surface of 25 the Flibe coolant itself.
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
158 1 The MHA analysis presented in Chapter 13 2 heavily leverages the methodology for -- that was in 3 the source term topical report that was under ACRS 4 review last year. That's KP-TR-012. The specific 5 assumptions include pre-transient diffusion of 6 radionuclides as neglected. This takes a little bit 7 of explanation.
8 This assumption maximizes the amount of 9 material at risk which accounts for inside the TRISO 10 fuel itself. By neglecting the fact that during 11 normal operations, material will naturally transport 12 and diffuse through TRISO barriers in steady state 13 before a transient condition which would deplete that 14 source of material at risk. We neglect that 15 phenomenon to maximize the amount of material at risk 16 in the fuel.
17 But at the same time, the amount of 18 material at risk assumes in the salt itself, reflects 19 an upper bound of the opposite assumption where a 20 maximal amount of material diffuses in steady state 21 from the fuel to the salt. So we have a hypothetical 22 super position of these two assumptions that 23 effectively double counts for the material that would 24 move from the fuel to the salt during normal 25 operation. So for the accident analysis, rather than 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
159 1 making a choice between in the fuel or in the salt, 2 that material is both in the fuel and in the salt for 3 the purposes of a hypothetical accident.
4 Hypothetical temperature histories are 5 presented in Chapter 13. These are specifically 6 designed to drive radionuclide release from the TRISO 7 fuel where diffusion happens at a higher rate at 8 higher temperature to drive radionuclides from the 9 graphite structures and to drive radionuclides from 10 the Flibe salt coolant where evaporation of different 11 species is higher with higher temperatures.
12 These are artificial, prescribed, flat 13 temperature profiles and while they drive the release 14 of radionuclides and the MHA, they also are important 15 input to the definition of figures of merit for the 16 postulated event analyses.
17 The next assumption has to do with the gas 18 base itself. And essentially everything that leaves 19 the free surface of the Flibe coolant is free to 20 transport to the site boundary in analysis space with 21 minimal reliance on the confinement of radionuclides 22 within the gas boundary itself and within the reactor 23 building itself. And so we minimize reliance on 24 retention in any physical structures and we -- in the 25 analysis presented in Chapter 13 are mostly focused on 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
160 1 the mitigative capability of both the TRISO fuel and 2 the salt.
3 Lastly, there's tritium modeling. We take 4 a conservative approach in two ways. First, the 5 tritium content that is inside the salt coolant and 6 inside the carbon matrix of the pebbles is assumed to 7 hypothetically puff release at the beginning of the 8 transient. That's a very non-mechanistic, 9 hypothetical way to treat that material at risk.
10 The second way is the tritium content 11 within the graphite reflector structure itself is 12 released by a bounding diffusion model that's driven 13 by a time and temperature curve which is also in 14 Chapter 13.
15 So the table at the bottom of the slide 16 shows the demonstration of margins of safety for the 17 Hermes reactor that's presented in Chapter 13. Our 18 criteria is the siting criteria in Part 100. That 19 includes the limit on whole body dose at the boundary 20 which is 25 rem for the worse two hours of the 21 accident. And also, thyroid dose has a limit of 300 22 rem.
23 Against these limits, the Hermes safety 24 analysis demonstrates over 24 rem margin to the whole 25 body limit and over 299 rem to the thyroid dose limit.
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
161 1 Before I move on to the next slide, are 2 there questions?
3 CHAIRMAN PETTI: Just a quick question.
4 You guys are the first ones really employing 5 functional containment and there's not a lot of 6 details here in the PSAR, you know. There's a jump 7 from the topical report on source term to this. We 8 will be identifying cross-cutting issues and although 9 your numbers are low and I sort of don't -- I think 10 based on what you're saying they kind of make sense to 11 me.
12 Will there be a document that we could 13 look at to look at the release faction from the TRISO 14 or the release faction from the salt, something that 15 puts the pieces together?
16 I just think -- not from a standpoint of 17 did you do it right, but because you're the first 18 using the functional containment, having some of that 19 data out there and having the ACRS being able to make 20 a statement about that I think is important. And it's 21 something that probably would only have to come 22 through in an RAI would be my guess. So it's also a 23 note to the staff.
24 I think, you know, given you guys are the 25 first, there might be some value there.
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
162 1 MR. HAGAMAN: I appreciate the comment.
2 The specific details are not in the Preliminary Safety 3 Analysis Report. I don't want to get too far ahead of 4 the NRC staff's review of what they think is adequate 5 to substantiate it, but I do appreciate the comment 6 and I do recognize that this is the first application 7 to use the functional containment and those details 8 are --- they certainly are of interest to us 9 internally and of interest on the on-going NRC review 10 and I think that's as far as I can take it right now.
11 CHAIRMAN PETTI: No, that's fine. It's 12 out there. Thanks.
13 MR. HAGAMAN: All right, so the last 14 slide, very briefly, as we discussed already, the 15 methodology and the sample results of the postulated 16 event analysis were provided with the expectation 17 again that the real quantitative results, based on a 18 more final version of the design will be available in 19 support of the operating license application.
20 The postulated event methods are provided 21 in the report KP-TR-018. You'll also see in there 22 some sample calculations that illustrate how the 23 methods will work to demonstrate that the events are 24 bounded by the consequences of the maximum 25 hypothetical accident analysis.
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
163 1 For each postulated event group, 2 acceptance criteria are defined and reported in both 3 Chapter 13 and in that postulated event technical 4 report. The acceptance criteria defined for the 5 figures of merit and these criteria will ensure that 6 the limiting case in each group has consequences that 7 are bounded by the MHA where we're demonstrating our 8 dose margins, meaning that the safety case relies on 9 surrogate criteria rather than full dose consequence 10 analysis for each minor event in the safety case.
11 As stated earlier, validation of the 12 models and the detailed final analyses of the specific 13 postulated event groups will be available in support 14 of the operating license application.
15 Thank you for your time. I look forward 16 to questions now and during the review later this 17 year.
18 MEMBER REMPE: Dave, this is Joy. I have 19 a question for you. I got assigned, I believe, the 20 event analysis review and Walt's assigned to the 21 Chapter 13 review and I think these two reviews are 22 very closely related.
23 Can we plan to our discussion on them at 24 the same time when we go through the future 25 assignments or schedule?
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
164 1 CHAIRMAN PETTI: So 13 and which one?
2 MEMBER REMPE: This KP-TR-018.
3 CHAIRMAN PETTI: Oh, right, right, right, 4 right. Yes, yes, yes.
5 MEMBER REMPE: And I don't know if the 6 staff is doing a SC on the topic report or the 7 technical -- but I don't think they usually do. But 8 let's do them together.
9 CHAIRMAN PETTI: Yes, no, I think there's 10 a lot of things where the order in which we do things 11 will be important, so we need to work with the staff 12 on that.
13 MEMBER REMPE: Okay. Thank you.
14 CHAIRMAN PETTI: So we don't drag it out.
15 Yes. I see Vicki has her hand up.
16 MEMBER BIER: Yeah. Vicki Bier. Quick 17 comment. This is really just following up on the 18 discussion with Jose earlier about the detailed design 19 features that preclude various types of events.
20 I don't want to make too big a deal out of 21 the wording, but the language that was used is, we are 22 looking for assumptions that allow us to preclude.
23 And really, the thought process should be, we are 24 looking for possible paths by which this could happen, 25 by which you could get in trouble, and then preclude 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
165 1 those paths.
2 And I don't think it's what you're doing, 3 but there's a risk that if you're trying too hard to 4 prove what you want to be true, you may prove it even 5 though it's not true. So just a caution on that, but 6 not a big concern at this point.
7 MEMBER MARCH-LEUBA: Yeah. And this is 8 Jose. This is what we've been calling start with a 9 blank sheet, and that always means a blank sheet is 10 having a questioning attitude: what can possibly go 11 wrong? And it's not clear that we are having that, to 12 me.
13 So, certainly, with the detail available 14 -- for example, this anti-siphoning (phonetic) thing 15 that we've been taking credit for, there's a circular 16 logic in the PSAR. Chapter 5.3 goes to 4.3, who goes 17 to 12.2, who goes to -- eventually back to 4.3 and 18 another describes. Yeah. There will be lots of 19 questions when we go over chapter by chapter.
20 MR. HAGAMAN: Thank you for the comments.
21 CHAIRMAN PETTI: Okay. So, just before we 22 -- you guys will be done, right? We'll be 23 transitioning to the staff next, this --
24 MR. HAGAMAN: Yes.
25 CHAIRMAN PETTI: Yeah. I just want to put 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
166 1 on the record that I particularly like your technology 2 development path, that slide, your testing, testing, 3 testing. I think that's -- it's going to inform the 4 design tremendously and fill in a lot of gaps. I 5 mean, some of the stuff, not until you get to Hermes 6 will you really know. But for a facility that's never 7 been built, for a technology that's never been built 8 before, I think it's commendable the approach you guys 9 are using.
10 With that, let's get the staff up because 11 we are really running out of time. My guess is that 12 we'll be done before 5:30, hopefully, but we're 13 probably going to go over a little bit.
14 MR. HELVENSTON: Yeah. This is Ed 15 Helvenston with the staff. I'm trying to get the 16 slides loaded up now. Are they showing up okay?
17 CHAIRMAN PETTI: Yep.
18 MR. HELVENSTON: Okay. Perfect. I'll go 19 ahead and get started, then. My name is Ed 20 Helvenston. I'm from the Non-Power Production and 21 Utilization Facility Licensing Branch in the Division 22 of Advanced Reactors and Non-Power Production 23 Utilization Facilities in the NRC's Office of Nuclear 24 Reactor Regulation.
25 I'm one of the three project managers for 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
167 1 the staff's safety review of Kairos's construction 2 permit application. And I'd like to follow the 3 technical presentations we just heard with a staff 4 presentation in which I'll give a brief overview of 5 the staff's review process and schedule, and I'll also 6 try to touch on a few other important topics relevant 7 to the staff's review of a construction permit 8 application for a non-power testing facility.
9 So, as you know, the NRC's receipt and 10 review of applications for construction and operation 11 of new reactors based on novel technologies, such as 12 Hermes, is an important milestone in the success of 13 advanced nuclear technologies in the U.S. Although 14 it's the responsibility of Kairos as the Applicant, 15 and other designers, to demonstrate the safety of 16 their designs, the NRC staff must perform its mission 17 of independently reviewing the safety of these designs 18 in an efficient and effective manner.
19 Accordingly, the staff's review of a 20 design such as Hermes will be focused on the matters 21 that are most safety significant. The scope of the 22 staff's review of a design is commensurate with the 23 risk posed by a design. Performing an efficient and 24 effective review of a design such as Hermes warrants 25 innovative and novel approaches.
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
168 1 So, in terms of overall responsibility for 2 the staff review of the Hermes application, this lies 3 with the Division of Advanced Reactors and Non-Power 4 Production Utilization Facilities, also known as DANU, 5 which is in the NRC's Office of Nuclear Reactor 6 Regulation. So DANU has primary responsibility for 7 licensing activities for all 10 CFR Part 50 testing 8 facilities, including non-power testing facilities 9 using advanced technologies such as Hermes.
10 One example of an innovative and novel 11 approach that the staff is using for the Hermes review 12 is the staff's core team approach. To support an 13 efficient and effective review, what the staff has 14 done is we've assembled a core review team of near 15 full-time and significant part-time staff, which 16 includes two advanced reactors project managers from 17 DANU, a non-power reactor project manager from DANU --
18 myself -- technical reviewers from DANU, as well as an 19 attorney from OGC.
20 In lieu of divvying specific review areas 21 among a wider array of technical reviewers as we've 22 done with many reviews in the past, in the core team 23 approach, we have DANU technical reviewers with 24 significant advanced reactor technology expertise who 25 are taking responsibility for broader portions of the 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
169 1 application as well as gaining an understanding of the 2 overall design.
3 The types of technical topics that are 4 being reviewed by the DANU core team include many of 5 the topics that are integral to the reactor design, 6 such as thermal and structural analysis, fuel and core 7 design, and accidents. Some of the other types of 8 topics that are being reviewed outside the core team, 9 similar to a more traditional approach by subject-10 matter experts, include areas such as, for example, 11 quality assurance, fire protection, site 12 characteristics, and emergency planning.
13 CHAIRMAN PETTI: Ed, just a question.
14 MR. HELVENSTON: Yeah.
15 CHAIRMAN PETTI: Is reactor physics sort 16 of a subset of one of those things you had on -- items 17 on the previous slide? Is it in, like, fuels or in --
18 (Simultaneous speaking.)
19 MR. HELVENSTON: I'm not sure that it 20 really fits into any of the ones here. These are just 21 example topics. I wouldn't call this an exhaustive 22 list.
23 CHAIRMAN PETTI: Okay. Just with a moving 24 fuel system, again, it's the first time the staff has 25 seen it. I think we want somebody that understands 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
170 1 physics and shut-down margins and all those physics-y 2 things.
3 MR. HELVENSTON: Absolutely. We're 4 certainly looking at those areas as part of our 5 review.
6 CHAIRMAN PETTI: Great. Thanks.
7 MR. HELVENSTON: So, in terms of NRC 8 licensing of non-power reactors, a 10 CFR Part 50 9 license for a non-power reactor could either be issued 10 as a Class 103 license for a commercial facility or a 11 Class 104(c) license for a research and development 12 facility.
13 In accordance with the NRC regulations in 14 the Atomic Energy Act as amended, any Class 104(c) 15 facility must be useful in the conduct of research and 16 development activities of certain types that are 17 specified in Section 31 of the Atomic Energy Act. The 18 specific distinctions between 103 and 104(c) are based 19 on certain financial tests that are described in NRC 20 regulations in the AEA about how much the cost of 21 operating a facility is spent on and recovered from 22 commercial activities as opposed to R&D activities.
23 And in its construction permit 24 application, Kairos has stated it plans to apply for 25 a Class 104(c) utilization facility operating license.
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
171 1 And accordingly, the staff is conducting its review of 2 the Hermes C application consistent with the 3 requirement that's given in Section 104(c) of the AEA 4 that in order to permit the conduct of widespread and 5 diverse research and development, the Commission 6 imposed only the minimum amount of regulation needed 7 to permit it to fulfill its obligations to promote 8 common defense and security and protect health and 9 safety.
10 So types of non-power reactors that are 11 defined in NRC regulations include both research 12 reactors and testing facilities. A testing facility 13 as defined in Part 50 is a reactor designed to operate 14 at a thermal power in excess of 10 megawatts or in 15 excess of 1 megawatt if the reactor is to contain 16 certain features.
17 A research reactor is, in general, a non-18 power reactor that is not a testing facility, for 19 example, because its thermal power is below 10 20 megawatts. Per the Part 50 definition, a testing 21 facility may also be a reactor of the type described 22 in 10 CFR 50 21(c), in other words, a Class 104(c) 23 facility that is useful in the conduct of research and 24 development.
25 Many of the prescriptive requirements in 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
172 1 10 CFR Part 50 are only applicable to nuclear power 2 reactors and therefore do not apply to non-power 3 research reactors and testing facilities. However, 4 testing facilities are subject to the siting 5 requirements, including accident reference doses in 10 6 CFR Part 100.
7 Testing facilities are also subject to a 8 few 10 CFR Part 50 requirements that do not apply to 9 research reactors, including a requirement for ACRS 10 review of CP and operating license applications, as 11 well as mandatory Commission hearings for CP 12 applications.
13 This slide just gives a brief overview of 14 the licensing process for a testing facility such as 15 Hermes. The process is generally similar during the 16 CP and OL application reviews. When an application is 17 received, the staff first performs an acceptance 18 review of the application to determine whether the 19 application contains sufficient information in scope 20 and depth for the staff to begin its detailed 21 technical review of the application.
22 Once an application is accepted, the staff 23 begins its separate safety and environmental reviews 24 in parallel. For the CP, the product of these reviews 25 is a safety evaluation report, or SER, and 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
173 1 environmental impact statement, or EIS. And for the 2 OL, another SER and EIS supplement are prepared.
3 Once the staff completes its safety review 4 and SER for a CP or OL, ACRS meetings are held, and 5 following the ACRS review and issuance of the ACRS 6 letter to the Commission, a Commission or Atomic 7 Safety and Licensing Board, if delegated by the 8 Commission, hearings are held on the Commission as 9 applicable.
10 For a CP, a mandatory hearing required by 11 10 CFR 50.58 is held on the sufficiency of the staff's 12 safety and environmental reviews for issuance of a CP.
13 In addition, for either a CP or OL, there is a 14 potential for separate contested hearings on the 15 staff's safety or environmental reviews if requested 16 by interveners. Following any hearing or hearings, a 17 decision is made to grant or deny a permit or license.
18 So, as consistent with the minimum 19 regulation requirement that I mentioned in Section 20 104(c) of the Atomic Energy Act, and also consistent 21 with the need to perform an efficient and effective 22 review of the Hermes CP application, the staff will 23 perform a risk-informed review in that its review 24 depth and scope will be commensurate with the safety 25 significance of areas under review in the application.
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
174 1 The staff is maintaining a big-picture 2 safety perspective of the Hermes design and is 3 tailoring the scope and level of detail review based 4 not only on the small size of Hermes but also on the 5 anticipated strong safety case and low radiological 6 consequences and considering that the application is 7 a CP application for a testing facility.
8 The staff is also tailoring its review to 9 the unique and novel Hermes technology described in 10 the CP application. The staff is using NUREG-1537, 11 which is the licensing guidance for non-power 12 reactors, in performing its review. NUREG-1537 is 13 designed to be technology neutral and provides 14 flexibility for a review such as the Hermes review.
15 In addition, NUREG-1537 Part 1, which provides 16 guidance to applicants, is the guidance that Kairos 17 used in preparing its CP application.
18 MEMBER KIRCHNER: Edward, this is Walt 19 Kirchner. Just a rhetorical question on your previous 20 slide, and you had mentioned this earlier, that you 21 look at the risk posed by a new applicant. So this 22 comment is independent of Hermes. In general, how do 23 you assess that risk going in?
24 What I mean is you have an advanced 25 reactor concept that hasn't been built and operated 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
175 1 previously. The risk is two things. One is the 2 frequency of potential for something to go wrong, and 3 the second part is the consequences. So, when you 4 talk risk in this sense, it seems to me you're using 5 that as a surrogate for the source term, essentially, 6 that the reactor has -- in other words, the thermal 7 power. Is that how you look at risk, or how do you 8 make that screening decision?
9 MR. HELVENSTON: The thermal power is 10 certainly one factor that you look at, but I don't 11 think we'd want to limit it to thermal power. Other 12 things would be the technology that they're using, and 13 in the case of Hermes, we're looking at the functional 14 containment concept and the idea that the Flibe and 15 the fuel will be able to retain fission products.
16 And it's a combination of the factors that 17 you're looking at, really, in determining the overall 18 risk and scaling the review of specific areas of the 19 facility appropriately with that. Yeah. I think you 20 would consider a wide range of factors in scaling your 21 review.
22 I'd say the staff would start with -- we 23 can start with an assumption of low risk, and we can 24 work with that, but certainly as we do our review, 25 that's something that we need to verify. And if we 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
176 1 find something that changes that assumption, then 2 maybe that's something that we need to go back and 3 take a closer look at.
4 MEMBER KIRCHNER: Thank you.
5 CHAIRMAN PETTI: Vesna, you have a 6 question?
7 MEMBER DIMITRIJEVIC: Yes. I have a 8 question related to this because I'm always ready --
9 when we say risk informed, we should really define 10 what risk we are talking about because if it's risk 11 informed, then it has to base on some metrics, right?
12 So, now, in your answer you gave so many of the 13 general -- you know, thermal energy, thermal power, 14 the containment.
15 And we were expecting there will be dose 16 related. So when you're doing this review, how are 17 you looking at this? Do you say, for example, that 18 your main metrics is, for example, vessel integrity 19 and foil integrity, or your main metrics is dose, or 20 your main metrics is challenges to this, or you are --
21 or maybe when you're doing review, you're just looking 22 in the safety systems and accident analysis.
23 How are you positioning yourself in this 24 review? What is your metrics when you're talking 25 safety this -- because there is no risk measures and 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
177 1 there is no risk relative ranking of the systems. So 2 what is your risk metrics?
3 MR. HELVENSTON: Well, I think at the end 4 of the day, the risk metrics we're really looking at 5 is health and safety. And that's quantified through 6 what the prospective dose could be. But we have to 7 look at a number of things kind of intermediately to 8 get there. We're certainly looking at the safety 9 systems that -- any mitigation functions they have and 10 the technology and how it's designed for mitigation.
11 MEMBER DIMITRIJEVIC: Okay. So it would 12 -- all right. So you're basically looking in the 13 mitigation of the maximum accident or all other 14 accidents which are considered -- okay. That will be 15 interesting to follow when we go through the review; 16 how did you position yourself in this prioritization 17 of the review? Okay. Well, something to think about.
18 Thanks.
19 MEMBER REMPE: So I have a question, and 20 I'm afraid I'm going to misquote what the Applicant 21 said. But they said they didn't ask for a finding on 22 safety at this time; they wanted a finding with 23 respect to how much margin would be required by the 24 staff.
25 And could you elaborate what, if -- I'm 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
178 1 probably misquoting exactly what they said, but how 2 you plan to do that? For example, if it were on the 3 dose to the 10 CFR 100 limits, are you going to say, 4 okay, you got to have at least a factor of 100 because 5 there's so much uncertainty in the data? Or what is 6 it they're asking for, and then how are you going to 7 plan to get there is what I'm curious.
8 MR. HELVENSTON: I don't want to speak for 9 Kairos, but they haven't requested final approval of 10 any portion of their design in this application. So 11 we're not approving a final design as any part of our 12 CP review, at least with what's been requested at this 13 point.
14 I do have a slide a couple slides from now 15 -- I will talk a little bit about the findings that we 16 are looking to make for a construction permit and kind 17 of how we determine what we need to look at in the CP 18 versus what we reasonably believe can be put off till 19 the OL, if that might be helpful.
20 MEMBER REMPE: I took a peek at that, but 21 I didn't see what -- I thought I heard them saying --
22 maybe they can speak up and clarify if I'm misquoting 23 them, but I thought that the guy that was the head of 24 the licensing came in when Jose was asking questions, 25 and he said, oh, we're not asking for a finding of 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
179 1 approval of the design with respect to safety. We did 2 ask for something with respect to how much margin the 3 staff would want.
4 And I was real curious because I wasn't 5 sure of that. But you've not done anything in your 6 last slide with respect to how much margin you're 7 expecting them to come in with that I can see.
8 MR. HELVENSTON: Yeah. I don't remember 9 the specific comment from Kairos. See, and if anyone 10 from Kairos wants to speak up and clarify, that's 11 fine.
12 MEMBER REMPE: Yeah. They asked for three 13 things, they said. And so, yeah, I'd like to hear 14 those again very carefully because Jose said he was 15 going to put it in the first paragraph of our letter.
16 MEMBER MARCH-LEUBA: Well, it may be the 17 last paragraph in our comment. But if you don't know 18 what they are asking to review, that's not a very good 19 statement to say in the --
20 MEMBER REMPE: No. Let's ask the Kairos 21 to clarify again, what were the three things they 22 asked for?
23 MR. GARDNER: Sure. This is Darrell 24 Gardner again from Kairos. I think what --
25 (Simultaneous speaking.)
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
180 1 CHAIRMAN PETTI: We can't hear you, 2 Darrell.
3 MEMBER REMPE: Darrell, could you speak up 4 again, please?
5 MR. GARDNER: There we go. How about now?
6 Can you hear me?
7 CHAIRMAN PETTI: Yeah. Now we can.
8 MEMBER REMPE: Much better. Thank you.
9 MR. GARDNER: Okay. So what I was saying 10 was somewhat paraphrasing from the findings that are 11 required in 10 CFR 50 35, so what the Commission is 12 required to conclude in 50 35 and what the 13 requirements are in 50 34(a) for a preliminary safety 14 analysis report. And so those are different from --
15 there not findings of final safety.
16 In fact, the language in 50 35 is fairly 17 clear that it doesn't represent any findings of final 18 safety acceptance of the design unless the Applicant 19 specifically requests for that, which we have not.
20 But it's simply an authorization to proceed with 21 construction. The exact language is the authorization 22 to proceed with construction but will not constitute 23 Commission approval of the safety of any design 24 feature or any specification, less the Applicant 25 specifically requests such approval.
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
181 1 So the point I was trying to make was if 2 you go back and look at the requirements of 50 35(a),
3 they are not demonstrating final safety design. What 4 it asks for is margins to safety, which we believe 5 we're providing with the MHA analysis.
6 MEMBER REMPE: So you're not asking for 7 them to say how much margin to have; you just want 8 them to determine that there is sufficient margin in 9 some vague sense? Because I wasn't sure of what I 10 heard, but I might have misheard you. Am I better 11 saying --
12 MR. GARDNER: I would say that that's 13 correct, absent the word vague. But yes.
14 MEMBER REMPE: Okay. Got it.
15 MR. HELVENSTON: Yeah. I'll just add that 16 I'd want to look at the wording of the regulation, but 17 in terms of margin, as Darrell said, Kairos is not 18 requesting and we're not making a final safety 19 determination.
20 But the margins are certainly one thing 21 that the staff would look at in the CP that would 22 support its -- making sure there is reasonable 23 assurance of adequate margin to support our 24 conclusions that we need to make for the CP, including 25 that there is reasonable assurance that the final 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
182 1 design is going to conform to the design bases.
2 MEMBER MARCH-LEUBA: Yeah. But how can 3 you be even confident -- not sure, generally sure, but 4 confident -- that you have evaluated the risk and that 5 you can say that this design has margin to safety if 6 you have not performed an evaluation? The Achilles 7 heel of all of this research analysis, I keep saying, 8 is completeness.
9 If you forget in your analysis the most 10 limiting event that actually melts the core and 11 produces a 10 CFR 100 dose, but you didn't analyze it, 12 then we keep saying there is no risk, I have a lot of 13 margin, but you didn't do the analysis. So, if you 14 don't do a thorough analysis, I don't think you can 15 say in your SER that we believe there is plenty of 16 margin to safety. You can say it's possible, but we 17 haven't done a complete analysis. You never do a 18 complete analysis.
19 So, I don't know. It is a bad position to 20 be on, but you should be very clear on the SER that 21 you have not performed a full evaluation, because, 22 honestly, I see an Olympic lack of rigor, especially 23 on the part of the staff, when it comes to an analysis 24 of safety.
25 And on the Applicant, I suspect the 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
183 1 Applicant has a lot more background documents that 2 they're not showing, and more background thinking that 3 they're not showing us, that probably supports the 4 position. But, on the part of the staff, I don't see 5 it.
6 MEMBER REMPE: Jose, how can you say that 7 when you haven't seen the SE from the staff?
8 MEMBER MARCH-LEUBA: I don't see an 9 attitude if I'm going to do a full safety --
10 MEMBER REMPE: I haven't seen that yet.
11 All I've seen is some slides about what they're going 12 to do. So I'm going to mention the previous reviews, 13 but we've come up with --
14 (Simultaneous speaking.)
15 MEMBER REMPE: Okay. So you're talking 16 about something else, but it's not here. Okay.
17 MEMBER MARCH-LEUBA: It happens. It 18 happens. It happens, and if you do a full analysis 19 and rigorous and really starting with a white piece of 20 paper, you always find something else. So unless you 21 have a rigorous approach or you have -- honestly, what 22 can possibly go wrong, instead of how well the we fix 23 what we thought of -- I don't know. I'll leave it 24 there.
25 MR. HELVENSTON: Yeah. Well -- and the 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
184 1 staff will certainly consider that feedback. But 2 we're still in the process of our review right now.
3 We certainly have a lot of questions in these areas as 4 well. I think it's been mentioned we have an ongoing 5 audit in terms of accident analyses right now, and 6 we're looking at some additional information that goes 7 in depth that supports some of what's in the PSAR.
8 So I'll just say the staff is certainly 9 looking at that and using its technical judgment to 10 make sure we ensure that the accident analyses are 11 comprehensive.
12 MEMBER MARCH-LEUBA: Yeah. I checked if 13 more information was on the -- access to more 14 information than was on the PSAR because I haven't 15 read it in detail yet because we're not performing the 16 review yet. But as I said, I've been looking through 17 his work while we were talking, and it's a circular 18 logic. It goes from Chapter 4.3 to Chapter 13-point-19 something to Chapter 12, and nowhere anything is 20 defined.
21 So I'll be looking forward to see if there 22 is any meat to the conclusions. And as I said -- I 23 mean, let me just -- want to put it in the record.
24 Number one, I think the Kairos and Hermes design are 25 cool. They are cool. They're really safe reactors.
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
185 1 They use the best technology available, all that. I 2 mean, this should be an example for the whole -- but 3 that doesn't give you carte blanche to not do the job.
4 Again, I think the Applicant is doing the 5 job, but in their offices. They're just not putting 6 it in the paper. So you have to show me you have 7 rigor on your what-can-possibly-go-wrong analysis.
8 And one more thing --
9 (Simultaneous speaking.)
10 MEMBER MARCH-LEUBA: Yeah. My house is 11 located 15 miles downwind from the location of this 12 reactor. And so I have a conflict of interest making 13 sure that this thing works. And even with my house 15 14 miles downwind of the reactor, I think it's a cool 15 reactor. I want it built. But I want it built 16 safety.
17 CHAIRMAN PETTI: Dennis, you've been 18 waiting.
19 DR. BLEY: Yeah. Yeah. I've been just 20 sitting here. When this whole thing came up during 21 the Applicant's discussion, I was a little taken aback 22 by the -- it's become clear it wasn't meant this way, 23 but by the idea that staff shouldn't be looking at 24 safety in a construction permit. And that's not 25 right.
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
186 1 And you are, again, looking at margins 2 without looking at safety. But at least from my point 3 of view, to get through and get a construction permit, 4 you need to show that you've looked pretty hard for, 5 as Jose says, the things that can go wrong, the 6 accidents that can happen, and that there are 7 plausible ways to deal with that.
8 And you don't do all the analysis. You 9 don't make a final safety finding at this stage. But 10 you have to make sure there's nothing hiding there 11 that implies there's a high chance that you'll never 12 be able to build this thing or that when you build the 13 structures during construction, you aren't locking 14 yourself into an area that could lead to high risk 15 later on. But I think you're doing that. So that's 16 all for me.
17 MR. HELVENSTON: Thank you for that 18 feedback.
19 CHAIRMAN PETTI: Keep going, Ed.
20 MR. HELVENSTON: All right. Well, on this 21 slide, I don't have much to say. I won't talk to this 22 in much detail. But this is just a list of the 23 chapters in NUREG-1537, which is similar to the layout 24 in Kairos's PSAR for Hermes, and we'll also use this 25 as the basic, basic format for the staff's SER.
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
187 1 And also, as noted on the slide, there's 2 a few chapters on here, for example, 15, -- 16, 17, 3 and 18, rather, that will not be applicable to this 4 review.
5 MEMBER REMPE: This is Joy, and I just 6 kind of wanted to bring up one thing that I thought 7 was important in some of the prior CP reviews. There 8 has been a section, an appendix or something, that 9 lists all of the assumptions and areas where further 10 work is needed. So it just is a nice way to keep 11 track of everything that -- the gaps. And will staff 12 produce such a list for this review? Have you guys 13 made a decision on that?
14 MR. HELVENSTON: We haven't made a 15 decision on that. That's certainly something we are 16 considering if there is a need to make sure we have 17 those types of commitments documented in one place.
18 I'm aware that we've done something similar with a 19 couple of the NPUF CP reviews in the past.
20 MEMBER REMPE: And one member's opinion, 21 I think it's a good idea to do something like that.
22 And it might be longer in some designs than others.
23 MR. HELVENSTON: I think I see one other 24 hand raised.
25 CHAIRMAN PETTI: Dennis, did you take --
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
188 1 MEMBER MARCH-LEUBA: That's Dennis.
2 CHAIRMAN PETTI: Did you take your hand 3 down? Thank you.
4 Jordan, did you have something you wanted 5 to add?
6 MR. HAGAMAN: No. That was from earlier.
7 Thank you.
8 CHAIRMAN PETTI: Okay. Thanks.
9 Keep going, Ed.
10 MR. HELVENSTON: I mentioned a couple 11 slides back that I wanted to talk a little about --
12 one other area I wanted to highlight was the 13 consideration, as we've discussed quite a bit 14 already, that Kairos has submitted an application for 15 a Hermes construction permit, and the staff is 16 conducting its review accordingly.
17 So safety reviews for either a CP or an OL 18 application are conducted in accordance with NRC 19 regulations. For CP, the level of detail in an 20 application and associated NRC staff review are 21 different than what is needed for an OL or a combined 22 operating license. A CP application describes a 23 preliminary design of a facility, while an OL 24 application needs to describe a final design as well 25 as additional administrative plans and programs that 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
189 1 are not provided in the CP application.
2 So the guidance in NUREG-1537 does not 3 differentiate between the level of detail that is 4 needed for a CP versus an OL application, nor does it 5 provide specific guidance on what types of things may 6 be deferred to the OL. However, in making this 7 determination on types of things that may reasonably 8 be deferred versus what is required for a CP, the 9 staff is using its technical judgment, and we also 10 certainly consider the requirements in 10 CFR 50 24(a) 11 and (b), which regard information that must be 12 included in either both preliminary and final safety 13 evaluation or safety evaluation reports -- or, I'm 14 sorry, safety analysis reports.
15 In addition, the staff bases its review on 16 the specific findings it needs to make for the 17 issuance of a CP, which are given in 10 CFR 50 35 and 18 I have listed here. So, as provided by 50 35, the 19 principal architectural and engineering criteria for 20 a design must be described in the CP application, but 21 some technical or design information may be left for 22 later consideration in an OL application.
23 And in addition, not all safety questions 24 need to be resolved for the issuance of a CP, but an 25 applicant must identify research and development which 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
190 1 has to be completed prior to the completion of 2 construction to resolve these questions. In addition, 3 in making a recommendation that a CP should be issued, 4 the staff also considers the requirements in 10 CFR 50 5 40 and 50 50.
6 So I think this is my last slide. This is 7 just giving the staff's current schedule for the 8 Hermes review. Given the extensive pre-application 9 engagement for the Hermes CP review, the staff was 10 able to establish an aggressive review schedule of 21 11 months from application acceptance, which includes 12 ACRS review but does not include a mandatory 13 Commission or Atomic Safety and Licensing Board 14 hearing.
15 The staff accepted the application for 16 review in November 2021 and completed a draft SER with 17 open items last month. The staff is currently 18 conducting audits in a variety of areas and also 19 preparing additional audits and possible requests for 20 additional information to support closure of open 21 items and completion of all SER chapters by November.
22 The staff also plans to complete 23 management and OGC reviews and approvals of the SER by 24 May 2023. I will note that the November 2022 and May 25 2023 dates on this slide are for completion of all 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
191 1 chapters in the SER. The staff intends to complete 2 some individual chapters ahead of these dates as 3 possible and plans to share complete chapters with the 4 ACRS well ahead of the May 2023 day as it is able.
5 To support completion of the review within 6 the 21-month schedule, the staff is targeting 7 September 2023 for issuance of an ACRS letter for 8 Hermes.
9 MEMBER REMPE: So this is Joy, and I was 10 thinking about this slide a bit more. And I'm 11 wondering -- we are involved in a review of an OL for 12 another NPUF, and it came to us with all of the open 13 items resolved. Sometimes we lost some of the 14 development activities because the staff didn't 15 include how -- we ask all of these REIs, and this is 16 how the issues were resolved.
17 And in light of that, we actually ask --
18 we see the earlier draft SE, and we actually also --
19 with this accelerated schedule, I'm thinking it might 20 behoove us to actually -- for those members who have 21 time and have other commitments later on the line 22 might want to see the draft SE too.
23 So have you guys made the draft SE that 24 you've got available to us? I know it won't be 25 something that we'll be discussing ever in an open 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
192 1 session what's in it, but it would behoove us to kind 2 of have access to it earlier in some cases --
3 (Simultaneous speaking.)
4 MR. HELVENSTON: We didn't have any 5 specific plan for that. I think that's something that 6 we have to discuss among the staff. I'd say 7 certainly, as you might be aware, there's initiatives 8 in terms of streamlining SEs and kind of focusing them 9 on really the most safety-relevant information, and 10 not necessarily including the level of back and forth 11 on RAIs and that type of thing, since that information 12 is already documented on the docket somewhere else.
13 But that's something that maybe when we 14 get a little bit closer to the November date for 15 completing an SE that we could discuss.
16 MEMBER REMPE: So you're saying that you 17 do not want to share the March 2022 draft SE with ACRS 18 at this time?
19 MR. HELVENSTON: I think we have to 20 discuss that among the staff a little more.
21 MEMBER REMPE: Okay. I just only last 22 week learned that, oh no, they've been submitting 23 changes to the CP, and there have been some design 24 changes. And I just think it might be good for us to 25 kind of be aware of things a little bit earlier.
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
193 1 Anyway, it's up to Dave and you guys, I guess, to 2 discuss that further.
3 CHAIRMAN PETTI: So, Ed, I would just 4 really push for -- because at least you can get some 5 chapters to us that's not -- from approved SER to 6 letter is really tight. So, if we're seeing stuff 7 early, even September 2022, I think that'll work 8 because we've got multiple reviews going on in 9 parallel.
10 MR. HELVENSTON: I understand. No, that's 11 helpful feedback.
12 MEMBER MARCH-LEUBA: Yeah. What were you 13 speaking to do between November 2022 and May '23?
14 Just the OGC review?
15 MR. HELVENSTON: So, based on the schedule 16 for this slide, yeah, that's correct. November is 17 essentially when the staff would have the SE 18 completed, and then the interim period until May 2023 19 is for the management and OGC reviews.
20 MEMBER MARCH-LEUBA: Yeah. We couldn't 21 even go over the technical parts before it's too late 22 change.
23 MR. HELVENSTON: Yeah, and we have to make 24 sure we're in process, certainly, and in terms of --
25 because I understand there's things about the draft 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
194 1 SE, SE chapters going to ACRS being made public. So 2 it's something we need to discuss with the staff and 3 certainly with OGC as well, just to make sure that 4 we're in process.
5 MEMBER REMPE: So it could be reference 6 material. But it might help with reviewing some of 7 the topical reports that are coming to us in the 8 interim.
9 MEMBER MARCH-LEUBA: That too.
10 DR. BLEY: If you talk with our staff, 11 you'll find there are arrangements we've made in the 12 past to see documents beforehand. It's when we're 13 coming to an ACRS meeting to discuss documents that 14 they have to be made public.
15 MEMBER MARCH-LEUBA: The PSAR and your SER 16 are completely non-proprietary, correct?
17 MR. HELVENSTON: The PSAR is non-18 proprietary; that's correct. The SER -- certainly, 19 the staff will strive to issue a non-proprietary SER.
20 I don't know if we've made a final decision on that 21 yet, though.
22 MEMBER MARCH-LEUBA: At the minimum, you 23 have to be sure non-proprietary mark-up.
24 MR. HELVENSTON: That's right. At a 25 minimum, there will be a non-proprietary mark-up.
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
195 1 CHAIRMAN PETTI: Anything else, Ed? Is 2 this the last slide, or --
3 MR. HELVENSTON: Yeah. This is the last 4 slide for me.
5 CHAIRMAN PETTI: Okay.
6 MR. HELVENSTON: I can certainly take any 7 other questions.
8 CHAIRMAN PETTI: No. You know what I'd 9 like to do, though, Ed, is have a meeting with Weidong 10 and you and whoever else, sort of at the project 11 management level. And we've made some initial 12 assignments of who is responsible for what, but now 13 that I better understand based on what I heard today, 14 I want to at least loop back with Weidong and maybe 15 you guys to -- I see some natural groupings of 16 chapters that could help accelerate the review and see 17 if we can get on the same page there and make sure 18 that I'm not missing something in terms of my thought 19 process. So if we can do that, I think that would be 20 good.
21 MR. HELVENSTON: Sounds good.
22 CHAIRMAN PETTI: So Weidong, if you'd try 23 to set something up, thanks.
24 Okay. Members, any other comments before 25 we go to the public?
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
196 1 MEMBER DIMITRIJEVIC: Sure. I would like 2 to make a general comment, Dave.
3 CHAIRMAN PETTI: Sure. Sure.
4 MEMBER DIMITRIJEVIC: This is Vesna 5 Dimitrijevic. After we have all of this discussion, 6 in the end, I don't think that you guys should 7 consider the big fact that your review is based on 8 this consecutive significance, because we don't know 9 too much. We don't know anything about risk, and we 10 know very little about safety significance.
11 So I would propose that you phrase this a 12 little more in the sense that as you have minimum 13 amount of regulation based on 104(c) and some 14 estimation of the safety impacts -- because in this 15 moment, as we see in one of your last slides, that the 16 most of the safety issue -- this is all qualitative, 17 and most of -- even if you look in mitigation systems 18 -- as we can see, light-water reactor, very often, 19 non-safety systems show to be safety significant. So 20 being safety or non-safety doesn't necessarily 21 preclude that.
22 So I will rephrase this as, based on 23 safety right significance. It's not going to be based 24 really on the realistic safety significance. So 25 that's my general comment.
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
197 1 MR. HELVENSTON: Well, thank you for that.
2 CHAIRMAN PETTI: Other comments, members?
3 Okay. Then let's go to public comment.
4 If you're a member of the public, if you're on the 5 phone, star-6. If you're on Teams, raise your hand, 6 and we'll recognize you and make your comment.
7 Okay. Not hearing any, I think that means 8 we are done. I want to thank both the staff and 9 Kairos. It was a most enlightening afternoon, lots of 10 ground to cover in a short amount of time. This went 11 about as I expected it would. We always have lots of 12 perspectives and interest in different areas, and you 13 can see we just love to probe because that's what we 14 like to do. But we really look forward to seeing this 15 come to fruition given its significance as the first 16 advanced non-light-water reactor.
17 With that, I will say we are done and end 18 our meeting. Everybody have a good weekend, and 19 members, we'll see you at May Full Committee. Thank 20 you all.
21 (Whereupon, the above-entitled matter went 22 off the record at 5:26 p.m.)
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
KP-NRC-2204-007 April 15, 2022 Docket No. 50-7513 US Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Kairos Power LLC Presentation Materials for Kairos Power Briefing to the Advisory Committee on Reactor Safeguards, Kairos Power Subcommittee, on Design Overview for the Hermes Non-Power Reactor This letter transmits presentation slides for the April 21, 2022, briefing to the Advisory Committee for Reactor Safeguards (ACRS), Kairos Power Subcommittee. At the meeting, Kairos Power will provide an overview of the design of the Hermes non-power test reactor which is currently under NRC staff review for a construction permit. This briefing is intended to provide a high level overview of the Hermes design prior to the ACRS review of the Hermes PSAR.
The content of this information is non-proprietary; Kairos Power authorizes the Nuclear Regulatory Commission to reproduce and distribute the submitted content, as necessary, to support the conduct of their regulatory responsibilities.
If you have any questions or need additional information, please contact Drew Peebles at peebles@kairospower.com or (704) 275-5388, or Darrell Gardner at gardner@kairospower.com or (704) 769-1226.
Sincerely, Peter Hastings, PE Vice President, Regulatory Affairs and Quality Kairos Power LLC www.kairospower.com 707 W Tower Ave, Suite A 5201 Hawking Dr SE, Unit A 2115 Rexford Rd, Suite 325 Alameda, CA 94501 Albuquerque, NM 87106 Charlotte, NC 28211
KP-NRC-2204-007 Page 2
Enclosures:
- 1) Presentation Slides for the April 21, 2022, ACRS Kairos Power Subcommittee Briefing xc (w/enclosure):
William Kennedy, Acting Chief, NRR Advanced Reactor Licensing Branch Benjamin Beasley, Project Manager, NRR Advanced Reactor Licensing Branch Weidong Wang, Senior Staff Engineer, Advisory Committee for Reactor Safeguards
Enclosure 1 Presentation Slides for the April 21, 2022 ACRS Kairos Power Subcommittee Briefing
Hermes Design Overview P RESEN TAT IO N FO R T H E AD VISO RY C O M M IT T EE O N REAC TO R SAFEGUARD S, K AIRO S P O W ER SUB C O M M IT T EE AP RIL 2 1 , 2 0 2 2 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
1 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Kairos Powers mission is to enable the worlds transition to clean energy, with the ultimate goal of dramatically improving peoples quality of life while protecting the environment.
In order to achieve this mission, we must prioritize our efforts to focus on a clean energy technology that is affordableand safe.
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
2 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Agenda
- Introduction
- Fuel/Core Design
- Reactor Vessel and Internals
- Heat Transport & Pebble Handling and Storage
- Structures
- I&C and Electrical
- Safety Case Copyright © 2022 Kairos Power LLC. All Rights Reserved.
3 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Introduction DRE W PE E BLE S - LICE NSING MANAGE R, SAF E TY Copyright © 2022 Kairos Power LLC. All Rights Reserved.
4 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Introducing Kairos Power Kairos Power Headquarters
- Nuclear energy engineering, design and manufacturing company singularly focused on the commercialization of the fluoride salt-cooled high-temperature reactor (FHR).
Founded in 2016 Current Staffing:
269 Employees (and growing)
~90% Engineering Staff
- Private funding commitment to engineering design and licensing program and physical demonstration through nuclear and non-nuclear technology development program. Kairos Power Team
- Schedule driven by the goal for U.S. commercial demonstration by 2030 (or earlier) to enable rapid deployment in 2030s.
- Cost targets set to be competitive with natural gas in the U.S.
electricity market.
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
5 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Kairos Power Design Approach Copyright © 2022 Kairos Power LLC. All Rights Reserved.
6 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Kairos Power Hermes Reactor Overview
- What?
KP-X / U-Facility A low power demonstration reactor that will prove Kairos Powers capability to deliver low-cost nuclear heat
- Why?
Operations Cost: Establish competitive cost through iterative learning cycles Supply Chain: Advance the supply chain for KP-FHR specialized ETU / Hermes components and materials while vertical integrating critical systems Design / Test: Deliberate and incremental risk reduction Licensing Approach: NRC will license Hermes as a non-power reactor and facilitate licensing certainty for KP-FHR Operations: Provide a complete demonstration of nuclear functions including reactor physics, fuel and structural materials irradiation, and radiological controls Hermes will ultimately demonstrate the U.S. aptitude to license an advanced reactor in a timely manner Copyright © 2022 Kairos Power LLC. All Rights Reserved.
7 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel/Core Design BRANDON HAUGH - SR. DIRE CTOR, MODE LING & SIMULATION NADE R SATVAT - MANAGE R, RE ACTOR CORE DE SIGN Copyright © 2022 Kairos Power LLC. All Rights Reserved.
8 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
KP-FHR Uses TRISO Fuel in Pebble Form
- Fuel Pebble (3 Regions):
Innermost portion is a low-density carbon matrix core Fuel annulus - Tri-structural isotropic (TRISO)-
coated fuel particles embedded in a carbon matrix Fuel-free carbon matrix shell
- Fuel qualification leverages U.S. DOE Advanced Gas Reactor program
- Core design is a pebble bed concept within a graphite reflector 4.0-cm diameter, annular fuel pebble is Pebbles are positively buoyant in Flibe the same size as a ping-pong ball Mixture of fuel and moderator pebbles operates with optimal moderation Copyright © 2022 Kairos Power LLC. All Rights Reserved.
9 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Hermes Core Design Power:
- 35 MWth
- 190 days average residence time Fuel Cycle:
- 4-6 passes
- Discharge burnup 6-8% FIMA
- Overall negative temperature reactivity coefficients Safety
- Negative fuel and moderator temperature reactivity coefficients Parameters:
- Negative coolant temperature, and void coefficients Method for
- High-fidelity Serpent 2 and KPACS (Serpent 2/Shuffling)
Calculation:
- Average Power per pebble = ~1000 W/pebble Power Profile:
- Pebble Peaking factor ~2
- Li-7 enrichment level and carbon to heavy metal atom ratio Coolant:
aligned to provide desired temperature reactivity coefficient Copyright © 2022 Kairos Power LLC. All Rights Reserved.
10 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Reactor Control
- Reactivity Control System (RCS)
Diversity:
- Reactivity Shutdown System (RSS)
- Compensate power defect, full xenon decay, operational excess reactivity, Shutdown and B4C depletion Margin (SDM)
- Single, most reactive rod failure Analysis:
- SDM to of 0.99 Sources of
- Core composition Operational
- Compensate change power levels or manage other transients Excess Reactivity:
Method for
- High-fidelity coupling tool, KPATH (Serpent 2/Star-CCM+)
Calculation:
- Drive mechanism sets limit on withdrawal rate (rate of reactivity insertion)
Other notes:
- KP-FHR has a strong (and prompt) Doppler feedback to reduce regular use of the RCS Copyright © 2022 Kairos Power LLC. All Rights Reserved.
11 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Core Design Methodology Safety Tools Nuclear Data Support Tools Copyright © 2022 Kairos Power LLC. All Rights Reserved.
12 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Representative Information Thermal Flux Fast Flux Flibe T Surface T Power 1x108 - 5x1014 n/cm2.s 550-700 °C 550-700 °C 0 - 26 W/cm3 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
13 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Reactor Vessel and Internals ODE D DORON - SR. DIRE CTOR, RE ACTOR SYSTE M DE SIGN Copyright © 2022 Kairos Power LLC. All Rights Reserved.
14 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Reactor Vessel and Internals Overview Copyright © 2022 Kairos Power LLC. All Rights Reserved.
15 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Hermes Coolant Circulation Path Overview Copyright © 2022 Kairos Power LLC. All Rights Reserved.
16 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Hermes Head Layout Copyright © 2022 Kairos Power LLC. All Rights Reserved.
17 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Hermes Reactivity Control and Shutdown System Drive Mechanism Motor driven sheave to position element Release Mechanism
- 1: Electromagnetic clutch
- 2: Motor isolation Hermes Core Layout 3x inbed shutdown elements 4x excore control elements Copyright © 2022 Kairos Power LLC. All Rights Reserved.
18 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Control Element Shutdown Element Control Element Shutdown Element Segmented Annular Design Cruciform Design Individual Capsules Inner Cladding contains absorber Argon fill Argon fill Absorber: B4C Absorber: B4C Cladding: SS-316H Cladding: SS-316H Copyright © 2022 Kairos Power LLC. All Rights Reserved.
19 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Heat Transport & Pebble Handling and Storage NICOLAS ZWE IBAUM - DIRE CTOR, SALT SYSTE MS DE SIGN Copyright © 2022 Kairos Power LLC. All Rights Reserved.
20 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Primary Heat Transport System (PHTS) - Overview
- The Primary Heat Transport System (PHTS) is responsible for transporting heat from the reactor to the ultimate heat sink (environmental air) during power operation and during normal shutdown
- The PHTS operates near atmospheric pressure and does not provide a safety-related heat removal function (see Decay Heat Removal System)
- The safety-related hot leg anti-siphon feature is performed by the Primary Salt Pump downward-facing inlet (the pump being supported in position by the Reactor Vessel upper head)
- Additionally, the PHTS provides for the following functions:
Contain and direct the reactor coolant flow between the reactor vessel and the heat rejection subsystem Manage thermal transients (overall thermal balance) occurring as part of normal operations Ensure minimum acceptable temperatures in the PHTS through make-up heating as necessary Provide capability to drain the PHTS to reduce parasitic heat loss during over-cooling transients Provide for in-service inspection, maintenance, and replacement activities Copyright © 2022 Kairos Power LLC. All Rights Reserved.
21 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
PHTS - System Makeup
- Reactor Coolant Flibe
- Primary Salt Pump (PSP)
Variable speed, cartridge style pump located on the reactor vessel head; inlet extends downwards through the Reactor Coolant free surface
- Heat Rejection Subsystem (HRS)
Provides for heat transfer from the reactor coolant to the atmosphere Consists of the heat rejection radiator, heat rejection blower, and associated ducting and thermal management
- Primary Loop Piping
- Primary Loop Thermal Management Provides non-nuclear heating and insulation to the PHTS as needed for various operations Copyright © 2022 Kairos Power LLC. All Rights Reserved.
22 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
PHTS - High Level Description Parameter Value Thermal duty 35 MWth Number of HRRs 1 Number of hot legs 1 Number of cold legs 2 Primary loop line size 8-12 in nominal pipe size HRR inlet coolant temperature 600-650°C HRR outlet coolant temperature 550°C Nominal flow rate 210 kg/s PHTS design pressure 525 kPa(g)
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
23 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Decay Heat Removal System (DHRS) - Overview
Purpose:
Vessel protection during postulated events for which the primary heat transport system (PHTS) is unavailable Operation: In-vessel natural circulation coupled to a passive water-based, ex-vessel system via thermal radiation and convection Continuous direct boil-off when estimated decay loads exceed parasitic losses Shutoff and isolated for low power levels (heat removal via parasitic losses only)
No change of state on reactor event initiation Load: Removal rate is a function of vessel temperature Due to physics of thermal radiation heat transfer Copyright © 2022 Kairos Power LLC. All Rights Reserved.
24 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
DHRS - Process Flow Diagram Steam Return
- DHRS does not directly interact with the primary coolant Leak Barrier Relief Storage Tank
- No change of state on onset of postulated events Always-on operation for set power levels Separator
- Parallel and independent cooling pathways Isolation Valve Four independent cooling loops Only three loops required to meet cooling demand Feedwater
- Dual-walled for leak prevention and detection
- Constricted to limit drain rate Continued heat removal in the presence of a leak
- Active component (isolation valve) failures do not introduce failures in heat removal Isolation valve fails in place (an operating system continues to operate)
Float valve nominally fails open Reactor Cavity Copyright © 2022 Kairos Power LLC. All Rights Reserved.
25 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
DHRS - Operation Normal Operation (DHRS deactivated)
Core (low/
No Power)
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
26 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
DHRS - Operation Normal Operation Core (High Power)
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
27 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
DHRS - Operation Transient Event (unrecoverable loss of PHTS, loss of electrical power, loss of feedwater)
Reactor trip Copyright © 2022 Kairos Power LLC. All Rights Reserved.
28 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Pebble Handling and Storage System (PHSS) - Overview
- Responsible for handling of fuel in Hermes, from initial on-site receipt, in-process circulation, and final on-site storage
- Major components of the system:
Pebble Extraction Machine (PEM): single screw for removing pebbles from molten salt Pebble Inspection System: performs flaw detection and burn-up measurement of removed pebbles Processing System: sorts pebbles into appropriate buffer storage channel based on pebble type Insertion System: stepper wheel feeder mechanism that inserts pebbles into the reactor via an in-vessel insertion line Storage System Canister: stores ~2,000 damaged or spent fuel pebbles in a non-critical configuration Storage Cooling Area: passively cooled, in-building storage area for spent fuel canisters New Pebble System: stores fresh fuel and prepares fuel for circulation via a high-temperature bakeout Copyright © 2022 Kairos Power LLC. All Rights Reserved.
29 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Recirculate Fuel New Pebble Other PHSS - Layout and Pebble Path Spent Fuel Moderator Copyright © 2022 Kairos Power LLC. All Rights Reserved.
30 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Structures BRIAN SONG - MANAGE R, CIV IL STRUCTURE S Copyright © 2022 Kairos Power LLC. All Rights Reserved.
31 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Reactor Building Layout Copyright © 2022 Kairos Power LLC. All Rights Reserved.
32 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Meteorological Loads
- Design considers rain, snow, wind, tornado and wind-borne missiles for site.
- Safety-related reactor building designed without crediting non-safety-related exterior shell for protection from snow, wind, rain, and missile loads.
- Exterior shell of safety-related reactor building designed with concrete thickness to protect safety-related structures, systems, and components (SSCs) from high-wind missiles, including debris from potential damage of non-safety-related reactor building.
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
33 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Flood loads
- Safety-related SSCs will be protected from internal flood (spray and accumulation) with shields, curbs, drains, etc.
- Safety-related Reactor Building protects safety-related SSCs from credible external flood.
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
34 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Seismic Loads
- Using risk-informed performance-based insights to define seismic design criteria (i.e. ASCE 43-19, SDC 3)
Seismic design basis earthquake based on site-specific seismic hazard considering other recent and nearby seismic hazard analyses and site-specific geotechnical characteristics.
- Safety-related Reactor Building incorporates spring/dashpot seismic isolation system, which lowers seismic demands on safety-related reactor building and safety-related SSCs in both horizontal and vertical directions.
- Moat and flex connections accommodate displacements of isolated safety-related reactor building.
- Safety-related portion of the Reactor Building will be represented by a three-dimensional finite-element model developed in accordance with Chapter 3 of ASCE 4-16.
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
35 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Instrumentation & Controls and Electrical Systems ANTHONIE CILLIE RS - DIRE CTOR, INSTRUME NTATION, CONTROLS AND E LE CTRICAL Copyright © 2022 Kairos Power LLC. All Rights Reserved.
36 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Instrumentation & Controls and Electrical System Design Relies on the Following Systems Robust Plant protection and control Inherent Safety
Safety Hazard Intervention and Event Limiting Defense
- Plant Control System (PCS)
System with Operational Reliability and Diagnostics
- Intelligent Health Monitoring Health Evaluation and Analysis in Real-Time
- Semi-autonomous control room (MCR)
Semi-autonomous Industrial Grade HMI Technology
- Electrical supply Basic Ohm Law Triangle (V = I.R)
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
37 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Plant Protection, Control, and Health Monitoring Operating Envelopes RPS PCS Health Monitoring Minimum dynamic operating envelope
- margin based on model fidelity Static operating envelope protecting nuclear and non-nuclear equipment integrity - non-safety-related equipment Maximum allowed static operating envelope - taking full advantage of safety margin, protecting nuclear safety related equipment Safety Margin - based on fuel temperature limitations, excess available reactivity and maintaining core geometry integrity Copyright © 2022 Kairos Power LLC. All Rights Reserved.
38 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Instrumentation and Controls Architecture Copyright © 2022 Kairos Power LLC. All Rights Reserved.
39 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Instrumentation and Controls Architecture Copyright © 2022 Kairos Power LLC. All Rights Reserved.
40 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Electrical Architecture Copyright © 2022 Kairos Power LLC. All Rights Reserved.
41 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Safety Case JORDAN HAGAMAN - DIRE CTOR, RE LIABILITY E NGINE E RING Copyright © 2022 Kairos Power LLC. All Rights Reserved.
42 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Safety Case Approach
- Deterministic approach consistent with NUREG 1537, Chapter 13
- To demonstrate compliance with regulatory dose limits, a Maximum Hypothetical Accident (MHA) that bounds the Chapter 13 postulated events is analyzed for dose consequences MHA not physical MHA includes conservatisms that maximize source term MHA includes a postulated release of radionuclides
- To ensure that the postulated events are bounded by the MHA:
List of postulated events is comprehensive to ensure that any event initiator with the potential for radiological consequences has been considered Initiating events and scenarios are categorized, so that a limiting case for each group can be qualitatively described in CPA (quantitative results will be provided with OLA)
Acceptance criteria are provided for the important figures of merit in each postulated event group to ensure the potential consequences of that event group remain bounded by the MHA as the design progresses Prevention of an event initiator is justified in PSAR Copyright © 2022 Kairos Power LLC. All Rights Reserved.
43 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
List of Events Postulated
- MHA - Hypothetical heat-up with conservative radionuclide transport
- Insertion of Excess Reactivity
- Salt Spills
- Loss of Forced Circulation
- Mishandling or Malfunction of Pebble Handling and Storage Systems
- Radioactive Release from a Subsystem or Component
- General challenges to Normal Operation
- Internal and External Hazard Events Copyright © 2022 Kairos Power LLC. All Rights Reserved.
44 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Maximum Hypothetical Accident
- Hypothetical heat-up event with conservative assumptions meant to drive radionuclide release:
Pre-transient diffusion of radionuclides from the fuel in the reactor core is neglected Prescribed hypothetical temperature histories are applied to the transient The gas space is not credited for confinement of the radionuclides that release from the Flibe-free surface Conservative, unfiltered, ground level releases Conservative tritium modeling A bounding vessel void fraction is assumed to facilitate the release of low volatility species in the vessel via bubble burst.
Whole Body Dose (rem) Thyroid Dose (rem)
Location and Duration 10 CFR 100 MHA Result 10 CFR 100 MHA Result Limit Limit Exclusion Area Boundary 25 0.227 300 0.235 (First 2 hrs at 250m)
Low Population Zone 25 0.059 300 0.081 (30 days at 800m)
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
45 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Postulated Events
- The postulated event methods are provided in KP-TR-018, Postulated Event Analysis Methodology (incorporated by reference in PSAR Ch. 13)
- The phenomena for each postulated event group that have the potential to increase dose consequence are identified as figures of merit
- Acceptance criteria are defined for the figures of merit that will ensure that the limiting event in each postulated event group is bounded by the MHA
- Validation and detailed final analyses of the postulated event groups will be performed for the operating license application Copyright © 2022 Kairos Power LLC. All Rights Reserved.
46 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
NRC STAFF SAFETY REVIEW OF THE KAIROS HERMES TESTING FACILITY CONSTRUCTION PERMIT APPLICATION Presentation to the Advisory Committee on Reactor Safeguards Thursday, April 21, 2022 Edward Helvenston, Project Manager Non-Power Production and Utilization Facility Licensing Branch, Office of Nuclear Reactor Regulation, U.S. NRC
Background
- The Kairos Hermes CP application, and other similar applications, represent a significant, watershed moment for nuclear energy and technology in the United States.
- Kairos and other designers and operators of new reactor technologies must demonstrate safety; however, for its mission of independently reviewing licensing applications for reasonable assurance of adequate protection of public health and safety, the NRC staff is committed to performing in an effective and efficient manner.
- The NRC staffs review focuses on matters that are most safety significant, and the scope of the review is commensurate with the risk posed by the designs.
- This type of review requires innovative and novel approaches.
2
Responsibilities and Coordination
- The Division of Advanced Reactors and Non-Power Production and Utilization Facilities (DANU), in the Office of Nuclear Reactor Regulation (NRR), has primary responsibility for licensing activities for testing facilities licensed under 10 CFR Part 50, including initial licensing of non-power reactors using advanced reactor technologies.
- Hermes review is using a core team approach Core team includes PMs and technical reviewers from DANU, and attorney from OGC One lead PM and two supporting PMs, including one non-power reactor PM Core team example topics: thermal analysis; structural analysis; fuels; source term; health physics Non-core subject matter expert (SME) example topics: human factors; quality assurance; fire protection; geology/seismic; emergency planning 3
Non-Power Reactor Licensing
- Non-power reactors licensed under 10 CFR Part 50 may be licensed as commercial facilities under Section 103 of the Atomic Energy Act of 1954, as amended (the Act), or as research and development facilities under Section 104c of the Act.
- In its CP application, Kairos states that it expects to apply for a Class 104c license, pursuant to 10 CFR 50.21(c), for a utilization facility useful in the conduct of research and development activities of the types specified in the Act.
- Therefore, the NRC staff is conducting its CP review consistent with Section 104c of the Act, which states:
The Commission is directed to impose only such minimum amount of regulation of the licensee as the Commission finds will permit the Commission to fulfill its obligations under this Act to promote the common defense and security and to protect the health and safety of the public and will permit the conduct of widespread and diverse research and development.
4
Non-Power Reactor Licensing (cont)
- Non-power reactor types defined in NRC regulations include research reactors and testing facilities
- Per 10 CFR Part 50 definitions, Testing facility means a nuclear reactor which is of a type described in [10 CFR 50.21(c)] and for which an application has been filed for a license authorizing operation at:
(1) A thermal power level in excess of 10 megawatts; or (2) A thermal power in excess of 1 megawatt, if the reactor is to contain:
(i) A circulating loop through the core in which the applicant proposes to conduct fuel experiments; (ii) A liquid fuel loading; or (iii) An experimental facility in the core in excess of 16 square inches in cross-section.
- Many 10 CFR Part 50 requirements are for power reactors and do not apply to non-power research reactors and testing facilities
- Testing facilities are subject to the requirements of 10 CFR Part 100, Reactor Site Criteria
- Testing facilities are subject to a few 10 CFR Part 50 requirements that do not apply to research reactors, including Advisory Committee on Reactor Safeguards (ACRS) review, and mandatory hearings for CP applications (10 CFR 50.58) 5
Testing Facility Licensing Process
Acceptance and docketing review Parallel safety and environmental reviews o CP: preparation of safety evaluation report (SER) and environmental impact statement (EIS) o OL: preparation of SER and EIS supplement ACRS review Hearing(s) o CP: mandatory hearing on sufficiency of staff safety and environmental reviews o CP and OL: potential for contested hearing(s)
Decision to grant or deny permit or license 6
Risk-Informed Review
- For its CP application review, the staffs review depth and scope will be commensurate with the risk or safety significance of items under review, and consistent with the minimum amount of regulation requirement in AEA Section 104c
- The staff will maintain a big picture safety perspective of the Hermes design. The staff will tailor the scope and level of detail of the review based on the small size of Hermes and anticipated strong safety case with low radiological consequences, and as appropriate for a testing facility CP application.
- The staffs review is also tailored to the unique and novel technology described in the CP application, using the appropriate regulatory guidance in NUREG-1537, Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors. Other guidance (e.g., regulatory guides and industry standards) and engineering judgement are also used, as appropriate.
7
NUREG-1537 Review Areas/Chapters
- 1. The Facility/Introduction 12. Conduct of Operations
- Emergency Planning
- 2. Site Characteristics
- Physical Security
- 3. Design of Structures, Systems,
- Operator Licensing and Components
- Startup Plan
- 4. Facility Description
- Human Factors
- 5. Coolant Systems
- Quality Assurance
- 6. Engineered Safety Features 13. Accident Analysis
- 7. Instrumentation and Control 14. Technical Specifications
- 8. Electrical Power Systems 15. Financial Qualifications
- 9. Auxiliary Systems 16. Other License Considerations
- 10. Experimental Facilities 17. Decommissioning
- 11. Radiation Protection and 18. Uranium Conversions Waste Management 19. Environmental Review 8 (Note that some NUREG-1537 chapters are not applicable to the Hermes CP application)
Construction Permits
- Safety reviews for CP and OL applications are conducted in accordance with the Commissions regulations
- The level of detail needed in a CP application and associated NRC staff SER are different than for an OL (or combined operating license (COL))
The CP application describes the preliminary design of the facility, while an OL application should describe the final design of the facility, as well as plans and programs not provided in the CP application
Facility has been described, including the principal architectural and engineering criteria for the design Further technical or design information may be reasonably left for later consideration in the final safety analysis report (i.e., OL application)
Safety features or components requiring research and development have been identified Safety questions will be resolved prior to the completion of construction and the proposed facility can be constructed with undue risk to the health and safety of the public
- Staffs conclusions are also based on the considerations in 10 CFR 9 50.40 and 50.50
Hermes Review Schedule
- Robust and effective pre-application engagement in order to optimize safety review (e.g., regulatory engagement plans, public meetings, topical reports, and pre-application audits
- 21-month review schedule (exclusive of mandatory hearing):
Milestone (Estimated) Completion Application Accepted November 2021 Draft SER with Open Items March 2022 SER Completion (all chapters) (November 2022)
Approved SER to ACRS (all chapters) (May 2023)
ACRS Letter (September 2023)
- Staff are currently conducting audits to support SER completion, including for structural design; effluents; decay heat removal system; accident analyses; instrumentation and controls; and site characteristics. Staff are also preparing 10 audits and possible requests for additional information (RAIs) on other topics.
NRC Staff Contacts NRC Safety PMs for Kairos Hermes CP review:
- Benjamin Beasley, Senior Project Manager, Advanced Reactor Licensing Branch 1 (301) 415-2062, Benjamin.Beasley@nrc.gov
- Samuel Cuadrado, Project Manager, Advanced Reactor Licensing Branch 1 (301) 415-2946, Samuel.CuadradoDeJesus@nrc.gov
- Edward Helvenston, Project Manager, Non-Power Production and Utilization Facility Licensing Branch (301) 415-4067, Edward.Helvenston@nrc.gov 11