ML22299A013
| ML22299A013 | |
| Person / Time | |
|---|---|
| Issue date: | 10/17/2022 |
| From: | Weidong Wang Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| NRC-2135 | |
| Download: ML22299A013 (1) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards Kairos Power Licensing Subcommittee Open Session Docket Number: (n/a)
Location: teleconference Date: Monday, October 17, 2022 Work Order No.: NRC-2135 Pages 1-93 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 LICENSING SUBCOMMITTEE 8 + + + + +
9 OPEN MEETING 10 + + + + +
11 MONDAY 12 OCTOBER 17, 2022 13 + + + + +
14 The Subcommittee met via Video 15 Teleconference, at 2:00 p.m. EDT, David Petti, 16 Chairman, presiding.
17 COMMITTEE MEMBERS:
18 DAVID PETTI, Chair 19 RONALD G. BALLINGER, Member 20 CHARLES H. BROWN, JR., Member 21 VESNA DIMITRIJEVIC, Member 22 GREGORY HALNON, Member 23 JOSE MARCH-LEUBA, Member 24 JOY L. REMPE, Member 25 MATTHEW 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 ALSO PRESENT:
2 BENJAMIN BEASLEY, NRR 3 MATT DENMAN, Kairos Power 4 TIMOTHY DRZEWIECKI, Kairos Power 5 DARRELL GARDNER, Kairos Power 6 RUSSELL GARDNER, Kairos Power 7 MICAH HACKETT, Kairos Power 8 RACHEL HAIGH, Kairos Power 9 BRANDON HAUGH, Kairos Power 10 MICHELLE HAYES, NRR 11 ISHAK JOHNSON, Kairos Power 12 RYAN LATTA, Kairos Power 13 GABRIEL MERIC, Kairos Power 14 SCOTT MOORE, ACRS 15 DREW PEEBLES, Kairos Power 16 NADER SATVAT, Kairos Power 17 NICOLE SCHLICHTING, Kairos Power 18 JEFF SCHMIDT, NRR 19 JIM TOMKINS, Kairos Power 20 CHRIS VAN WERT, NRR 21 GARETH WHATCOTT, Kairos Power 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 CONTENTS 2 ACRS Chairman Introductory Remarks . . . . . . . 5 3 NRC Staff Introductory Remarks . . . . . . . . . 7 4 Kairos Power Introductory Remarks . . . . . . . . 9 5 KP-FHR Fuel Qualification Methodology . . . . . 12 6 KP-FHR Fuel Qualification Methodology 7 Topical Report Safety Evaluation . . . . . . . . 67 8 Public Comments . . . . . . . . . . . . . . . . . 91 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
5 1 P R O C E E D I N G S 2 2:00 p.m.
3 CHAIR PETTI: Good afternoon, everyone.
4 The meeting will now come to order 5 This is a meeting of the Kairos Power 6 Licensing Subcommittee of the Advisory Committee on 7 Reactor Safeguards.
8 I'm David Petti, Chairman of today's 9 Subcommittee meeting.
10 ACRS members in attendance are Charles 11 Brown, Greg Halnon, Jose March-Leuba, and Ron 12 Ballinger. Dennis Bley and Steve Schultz, our 13 Consultants, are also online.
14 Weidong Wang, of the ACRS staff, is the 15 Designated Federal Official.
16 And I forgot Joy Rempe is also online.
17 During today's meeting, the Subcommittee 18 will review the staff's Safety Evaluation on the 19 Topical Report entitled "Fuel Qualification 20 Methodology for the Kairos Power Fluoride Salt-Cooled 21 High Temperature Reactor," Revision 2.
22 The Subcommittee will have presentations 23 by and hold discussions with the NRC staff, Kairos 24 Power representatives, and other interested persons 25 regarding this matter.
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 The product presentations by the Applicant 2 and the NRC staff may be closed in order to discuss 3 information that is proprietary to the Licensee and 4 its contractors, pursuant to 5 USC 552b(c)(4).
5 Attendance at the meeting that deals with such 6 information will be limited to the NRC staff and its 7 consultants, Kairos Power, and those individuals and 8 organizations who have entered into an appropriate 9 confidentiality agreement with them. Consequently, we 10 need to confirm that we have only eligible observers 11 and participants in the closed part of the meeting.
12 The rules for participation in all ACRS 13 meetings, including today's, were announced in The 14 Federal Register on June 13th, 2019. The ACRS section 15 of the U.S. NRC public website provides our Charter, 16 Bylaws, agendas, Letter Reports, and full transcripts 17 of all full and Subcommittee meetings, including 18 slides presented there. The meeting notice and agenda 19 for this meeting were posted there.
20 We have received no written statements or 21 requests to make an oral statement from the public.
22 The Subcommittee will gather information, 23 analyze relevant issues and facts, and formulate 24 proposed positions and actions, as appropriate, for 25 deliberation by the full Committee.
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 The rules for participation in today's 2 meeting have been announced as part of the notice of 3 this meeting previously published in The Federal 4 Register.
5 A transcript of the meeting is being kept 6 and will be made available, as stated in The Federal 7 Register notice.
8 Due to the COVID pandemic, today's meeting 9 is being held over Microsoft Teams for ACRS, NRC 10 staff, and the Licensee attendees.
11 There's also a telephone bridge line 12 allowing participation of the public over the phone.
13 When addressing the Subcommittee, the 14 participants should first identify themselves and 15 speak with sufficient clarity and volume, so that they 16 may be readily heard. When not speaking, we request 17 that participants mute your computer microphone or 18 phone by pressing *6.
19 We'll now proceed with the meeting, and 20 I'd like to start by calling upon NRR management.
21 Michelle Hayes will now make an opening statement.
22 MS. HAYES: Thank you, Dr. Petti.
23 I'm Michelle Hayes, Chief of Technical 24 Branch 1 in the Division of Advanced Reactors and Non-25 Power Production and Utilization Facilities in 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 Office of Nuclear Reactor Regulation.
2 We're happy to be meeting with you today.
3 As you know, the Hermes Test Reactor Construction 4 Permit Review is underway. The Topical Report we're 5 discussing today, and two others that we're going to 6 bring to you early next year, are referenced in this 7 Hermes application. So, these will need to be 8 finished before we complete the Construction Permit 9 Review.
10 We met with you on the Kairos Fuel 11 Performance Topical Report a year ago. The Fuel 12 Performance Report described a methodology for 13 modeling TRISO failed fuel fraction and fission 14 product released from the TRISO particles. Today, we 15 are discussing the Fuel Qualification Topical Report.
16 Kairos relies on the previously-approved 17 EPRI Topical Report for qualification of the TRISO 18 fuel particles. The Kairos Fuel Qualification Report 19 gives details on the qualification of the pebble form 20 of the fuel which will be used in their fluoride salt-21 cooled reactors.
22 The Kairos Report provides a method for 23 qualification that considers mechanical and structural 24 performance, as well as chemical, thermal, and 25 irradiation effects.
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 After Kairos gives an overview of the Fuel 2 Qualification Report, NRC staff will give you an 3 overview of our report, our review and our Safety 4 Evaluation.
5 We will be glad to hear your insights and 6 comments. Are there any questions before we get 7 started?
8 Then I will turn it back over to Dr. Petti 9 or Kairos.
10 CHAIR PETTI: I just noticed that Vesna 11 Dimitrijevic has joined. So the court reporter can 12 report her as present.
13 Jim, it's all yours.
14 MR. TOMKINS: Okay. Thank you, Dr. Petti.
15 My name is Jim Tomkins, and I'm Manager of 16 Fuel Licensing at Kairos Power.
17 Today, we're going to present our 18 methodology for qualifying our fuel for the Kairos 19 Power Reactors. Ryan Latta, who is our Principal 20 Engineer for Fuel Qualification, will be doing the 21 bulk of the presentation today.
22 We have individuals at various Kairos 23 locations, and I'm going to start with KP Headquarters 24 in Alameda, California. I just introduced myself.
25 Go ahead, Ryan.
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 MR. LATTA: Yes, my name is Ryan Latta.
2 I'm a Principal Engineer for Fuel Qualification, and 3 I'll be giving most of the main technical talk today.
4 MR. JOHNSON: I'm Ishak Johnson. I'm a 5 Safety Analysis Engineer.
6 MR. MERIC: Gabriel Meric, Engineering 7 Fueling Materials.
8 MR. SATVAT: Hello. This is Nader Satvat, 9 Senior Manager of Core Design.
10 MR. DRZEWIECKI: I'm Tim Drzewiecki. I'm 11 a Senior Engineer, Safety Analysis.
12 MR. TOMKINS: Okay. Thank you.
13 In Charlotte, North Carolina, could folks 14 introduce themselves?
15 MR. D. GARDNER: Darrel Gardner, Senior 16 Director of Licensing.
17 MR. PEEBLES: And we've got Drew Peebles.
18 I'm a Licensing Manager for Safety.
19 MS. SCHLICHTING: Nicole Schlichting, 20 Senior Licensing Engineer.
21 MS. HAIGH: Rachel Haigh, Licensing 22 Engineer.
23 MR. PEEBLES: And that's it in Charlotte, 24 Jim.
25 MR. TOMKINS: Okay. And how about KP 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 Southwest?
2 MR. DENMAN: This is Matthew Denman. I'm 3 the responsible Engineer for Mechanistic Source Term.
4 MR. TOMKINS: Okay. Did I miss anyone?
5 Is anybody calling in by phone? I think so.
6 MR. WHATCOTT: Jim, I'm online. This is 7 Gareth Whatcott, Lead Engineer for Fuel Handling and 8 Storage.
9 MR. TOMKINS: Okay.
10 MR. HAGAMAN: Jordan Hagaman, Director of 11 Reliability Engineering and Quality Assurance at 12 Kairos Power.
13 MR. R. GARDNER: And Russell Gardner, 14 Senior Engineer of Fuel Performance.
15 MR. TOMKINS: Anyone else? How about 16 Micah?
17 Well, somebody should send Micah a Slack, 18 by the way. But is there anyone else who's on the 19 line for Kairos?
20 Okay. Rachel, do you want to go ahead and 21 bring up the slides?
22 While she's doing that, I just wanted to 23 touch again on proprietary and non-proprietary 24 materials. The slides are non-proprietary, but it's 25 conceivable that in the course of answering a question 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 we might have to reveal some proprietary information.
2 So, if we do that, we will kind of capture the 3 question and cover that during the closed session.
4 And with that, I'll turn it over to Ryan.
5 Next slide.
6 Actually, I'm turning it over to myself.
7 Sorry about that.
8 So, the applicability of this Topical 9 Report, as I've said before, it presents the 10 methodology for qualifying fuel for use in KP-FHRs.
11 Qualification is subject to the conditions in the 12 Topical Report.
13 I want to make a point that this Topical 14 Report is a methodology for qualification. It is not 15 the qualification. That's going to have to be 16 demonstrated over the coming months and year or so.
17 And that qualification will be documented in Safety 18 Analysis Report documents as part of licensing 19 applications.
20 The Topical is applicable to a test or 21 power KP-FHR, provided that the conditions are met, 22 but some of the conditions apply to one or the other.
23 Next slide.
24 So, qualification. So, qualified fuel 25 means fuel for which there's a reasonable assurance 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 that the fuel, if it's fabricated in accordance with 2 its specification, will perform consistently with the 3 Safety Analysis. So, that's kind of a working-level 4 definition we've been using.
5 And now, I'll turn it over to Ryan, who is 6 going to talk a little bit about our design and our 7 fuel, and then, he'll go through the qualification 8 methodology.
9 CHAIR PETTI: So, Jim, this is Dave. Just 10 a question.
11 So, this report outlines all of the tests, 12 analytical approaches, whatever you want to call it, 13 that when taken together, collectively constitute fuel 14 qualification from a scope perspective?
15 MR. TOMKINS: Yes.
16 CHAIR PETTI: Okay. Thank you.
17 MR. LATTA: Okay. Can you advance one 18 slide?
19 MR. TOMKINS: Rachel, next slide. Next 20 slide.
21 MR. LATTA: Yes, one more slide. Thank 22 you.
23 So, this is Ryan Latta speaking now.
24 So, as a point of reference for the FHR, 25 which is the application of the fuel, we have this 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 slide. And so, we have two reactors here. There is 2 Hermes Test Reactor, which is a non-power test 3 reactor, and there's, farther down road, future KP-X, 4 which is a commercial electric power reactor.
5 The kind of characteristics of the reactor 6 are given here. Flibe coolant, graphite reflector.
7 All of them use the same fuel on the design, which is 8 a pebble fuel containing TRISO fuel particles.
9 The power of the Hermes, 35 megawatts, 10 thermal; KP-X, 10 times greater in power. Both are 11 low pressure systems, have low pressure systems below 12 200 kPa. Inlets, 550 C, and outlets, 620 to 650 C.
13 And on the right is a schematic of the 14 reactor. You can see the vessel outlined. There's a 15 white space between the inner cavity where the pebbles 16 are contained, which is the core, and the graphite 17 reflectors outside of that, and then, the vessel wall.
18 And so, the pebbles are contained within 19 that inner cavity. They're in a packed-bed formation 20 with Flibe coolant flowing from top to bottom and from 21 bottom to top in the reactor. And the pebbles also 22 enter in the bottom at the fuel chute, and then, they 23 exit the reactor at the defueling chute at the top of 24 the reactor.
25 And so, the pebbles are buoyant in 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
15 1 Flibe coolant and the bed itself is in a packed 2 configuration, and the pebbles move very slowly over 3 time through the core, and then, are recirculated and 4 inspected, and then reintroduced into the bottom of 5 the core until they reach their limits, specifically, 6 for burnup.
7 MR. TOMKINS: Any questions on that>?
8 Okay. So, next slide.
9 MR. LATTA: Okay. This is a little 10 schematic of the annular fuel pebble and the TRISO 11 fuel particle. The TRISO particle shown here is 12 typical of what you have seen before, a UCO kernel 13 with multiple coating layers of PyC, and then, a SiC 14 layer.
15 The fuel particles are contained within 16 the fuel pebble -- this pebble, specifically 40 17 millimeters in diameter, which is the size of a ping 18 pong ball. Special to this design is that the pebble 19 has three regions. There's an inner region that is a 20 lower density than the rest of the matrix material.
21 Then, there's a fuel region that contains 22 the TRISO particles, and then, outside the fuel region 23 there's a shell that's free of fuel and that separates 24 the fuel from the surface of the pebble.
25 Next slide, please.
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 MEMBER REMPE: This is Joy.
2 MR. LATTA: Uh-hum?
3 MEMBER REMPE: Can we go back to the prior 4 slide, please?
5 You're right, we've seen this before. But 6 this pebble and the way it's fueled is different than 7 the German fuel because of this low density core 8 region. But are there other differences? Are the 9 pebbles packed more closely than the German fuel? And 10 this fuel-free outer matrix shell, how does that 11 differ from what we've seen in Germany or what's being 12 done in China, for example?
13 MR. LATTA: Sure. So, I will go over the 14 differences.
15 So, first off, the pebble is smaller in 16 diameter. It's 40 millimeters versus 60 millimeters.
17 We have this interior lower density core, and that's 18 to allow the pebble to be net buoyant within the 19 Flibe. That does not exist in the historic German 20 pebble.
21 The fuel region contains a higher packing 22 fraction of particles than historically have been done 23 with German pebbles, but it's consistent with what has 24 been done with compacts, and specifically, with AGR 25 compacts.
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 The fuel-free outer shell is thinner in 2 dimension than has historically been used in the 3 German pebbles.
4 MEMBER REMPE: Thank you.
5 At some point, I guess I'd be interested 6 in how you feel comfortable that this tighter packing 7 is not going to damage the coatings of the particle.
8 MR. LATTA: Sure. So, in the 9 manufacturing/development program we have, we'll be 10 fabricating these with surrogate materials and proving 11 through deconsolidation-leach-burn-leach after 12 fabrication that the defect fraction of particles 13 post-fabrication are within the specifications. So, 14 we'll be able to demonstrate through sampling of 15 product that we meet our specification.
16 MR. TOMKINS: And the particles are 17 overcoated. So, they have a built-in, you know, 18 separation, if you will.
19 MR. LATTA: Yes. So, all particles are 20 overcoated, and then, poured into these molds to 21 fabricate and press this region. And so, there's 22 specifications on that as well to ensure that those 23 things are met.
24 MEMBER REMPE: So, remind me what this 25 overcoating is composed of? And do you have 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
18 1 irradiation data to show how it works? I mean, that 2 was not done in the AGR tests, right?
3 MR. LATTA: It was done. So, overcoating 4 is --
5 MEMBER REMPE: Oh, it was done? Okay.
6 MR. LATTA: Overcoating is a traditional 7 method for packing and keeping particles separated 8 from one another through many of the programs that 9 exist, you know, internationally or domestically.
10 So, you roll the particles in the matrix 11 material. All the matrix material, the three zones, 12 is the same material. It just has, you know, either 13 has a lower density from having more -- fabricated 14 with more porosity or it's fabricated with TRISO 15 particles embedded in it.
16 MEMBER REMPE: Is the packing fraction 17 tighter than what was done in AGR-1 compacts?
18 MR. LATTA: No, it's within that range.
19 MEMBER REMPE: Okay. Thank you.
20 CHAIR PETTI: So, Ryan, since this was 21 brought up -- I was going to bring it up later --
22 MR. LATTA: Okay.
23 CHAIR PETTI: -- deconsolidation-leach-24 burn-leach is not a perfect QC technique. And the 25 concern in pressing is (a) you're right, breaking 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 particles, but (b) partial cracks in layers that would 2 pass through the QC, and the cracked particles, under 3 irradiation, the cracks potentially growing. This is 4 just one of the concerns I have with the qualification 5 approach. As we get into it a little bit more maybe 6 later in the presentation, or even in the closed 7 session, we can talk some additional details.
8 MR. LATTA: Okay. Thank you.
9 MR. TOMKINS: Okay. Next slide.
10 MR. LATTA: Okay. I was just going to go 11 through these parts more individually, as I've already 12 done a little bit just before.
13 So, the kernel is a UCO kernel. It's a 14 mixture of UO2 and uranium carbide phases. So, this 15 is where the uranium is and where the fission occurs, 16 and the fission products are generated. Outside of 17 the UCO kernel is a porous carbon buffer layer. This 18 layer kind of serves as the plenum for fission product 19 gases generated in the kernel and, also, mechanically 20 separates the kernel from the structural PyC and SiC 21 layers.
22 On top of that is the IPyC layer. So, 23 this is the first real structural layer and barrier, 24 fission product barrier of the fuel particle.
25 You can go to the next 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
20 1 MR. TOMKINS: Rachel, next.
2 MR. LATTA: So, after the IPyC is the SiC 3 layer. So, this is a silicon carbide layer that is 4 the primary structural layer and fission product 5 barrier to prevent fission product release.
6 The next layer on top of that is the OPyC 7 layer. This is kind of the final and secondary layer 8 of barrier for fission product retention structural 9 barrier or structural component of the particle.
10 And then, finally, as we had just 11 described, in fabrication, you overcoat the particles, 12 and then, they're pressed into the fuel region to 13 obtain your nominal packing fraction.
14 MR. TOMKINS: Okay. Next.
15 MR. LATTA: And now, talking about the 16 features of the pebble design itself.
17 So, first off, going from interior to 18 exterior, on the interior is the low carbon core, low 19 density carbon core. And so, the objective of this 20 core is that is reduces the overall density of the 21 pebble, so that it is net buoyant in the Flibe 22 coolant.
23 Then, outside of that region is a shell of 24 fuel-containing matrix material. And so, the 25 advantage of this is that the fuel is moved to 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
21 1 outside of the pebble, and this lowers the fuel 2 temperature for a given power rating versus if the 3 fuel was uniformly distributed throughout the whole 4 pebble. So, this helps you obtain higher power 5 density, lower temperatures in an FHR.
6 And then, finally, there's the fuel-free 7 outer shell. And so, this is a region of the same 8 matrix material that separates the fuel region from 9 the Flibe or exterior environments and protects the 10 fuel from mechanical damage.
11 MEMBER BALLINGER: This is Ron Ballinger.
12 I have a question relating to the low 13 carbon density core. How much margin do you have, or 14 does it really matter, where if you get a change in 15 density pebble-to-pebble, it alters the migration rate 16 through the core? Is that an issue?
17 MR. LATTA: You're worried about migration 18 of fission products through the core?
19 MEMBER BALLINGER: No, no. Migration of 20 -- excuse me -- movement of the pebble, of the fuel 21 pebble itself through the core.
22 MR. LATTA: Oh, yes. Okay. So, we do 23 expect the pebble to densify with accumulated fluence.
24 There's also a distribution of allowable densities 25 from the fuel specification, and the density 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
22 1 pebble is set relative to the Flibe density, such that 2 it would be able to maintain positive buoyancy even 3 with the extreme bounding conditions of what the 4 density could become with irradiation.
5 MEMBER BALLINGER: So, I guess when you 6 measure the burnup of pebbles that exit the core 7 against what you might expect it to be, you would 8 notice if there was something funny going on?
9 MR. LATTA: We would also be performing an 10 inspection. So, there would be a visual inspection of 11 the pebbles, and we would be able to examine the 12 diameter of the pebble through that process.
13 MEMBER BALLINGER: No, no. I guess what 14 I was saying was you anticipate by analysis, or 15 whatever, that the pebble that exits the core has a 16 certain burnup, and then, you measure it and you 17 discover that the burnup is actually X plus or minus.
18 Is that an indicator that the pebble has migrated 19 through the core at a different rate than expected?
20 MR. LATTA: It could potentially be. If 21 the burnup was significantly larger than expectation 22 or significantly lower, then that could be an 23 indication that the pebble had traversed either 24 slowly --
25 MR. TOMKINS: By the way, these pebbles 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 move kind of en masse. I mean, there isn't that much 2 room in there. So, you're not going to have one 3 pebble that speeds ahead of the others. We've done 4 visuals of this process.
5 MEMBER BALLINGER: Okay. All right.
6 Okay. Because I recall an experiment that Andy Kadak 7 did a very long time ago where he mixed the colors of 8 the pebbles and looked at the migration rate through 9 the core, and the density did make a difference in 10 that case -- yellow and red and green pebbles, believe 11 it or not.
12 MR. HACKETT: And we do expect a 13 distribution in the migration pathway for the pebbles 14 anyway, and we're accounting for that. And that's the 15 reason why we do the pebble inspection, to ensure that 16 the pebbles are extracted within the expected burnup 17 range that we have, the limits that we have for 18 burnup.
19 MR. TOMKINS: By the way, that was Micah 20 Hackett, who is our Director of Fuel and Materials.
21 MEMBER BALLINGER: Thank you.
22 MR. TOMKINS: Okay. Next slide.
23 MR. LATTA: So, one more slide, please.
24 All right.
25 So, this is an outline of the sections 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
24 1 the methodology. I'll go through each one of these 2 points more in-depth through the next series of 3 slides.
4 To start out with, they're just talking 5 about historical experience and ties to AGR and the 6 EPRI TRISO Topical Report, and discuss an internal 7 PIRT we perform for the fuel pebble and TRISO 8 particle, and discuss more on manufacturing after 9 that, the specification and QC to control quality 10 through inspection.
11 Next, I'll talk about the fuel 12 qualification envelope and operating range for the 13 fuel, and what we do to be within that or external to 14 that.
15 Next slide, please.
16 MEMBER REMPE: This is Joy.
17 And actually, I think it fits better on 18 that prior slide. I had a couple of questions that 19 are, I think, at a higher level.
20 Again, it's related to whether you decide 21 you want to do an irradiation test, and if the 22 operation is going to be within the bounds of the 23 qualification envelope.
24 Say Hermes doesn't need to have additional 25 irradiations, but you think the larger one 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
25 1 because of something or other. And I guess I'm 2 curious on the something or other, because don't you 3 need validated codes to determine that, and will you 4 have the codes validated for the larger plant? Or 5 even for Hermes to decide that you don't need it, are 6 the codes validated? So, I'm wondering if it's a 7 roundabout argument to decide I don't need irradiation 8 data.
9 And then, the second question I had is, 10 where would the irradiation -- I mean, I saw in the 11 text it talks about the facility and it seems like 12 it's going to be of the whole pebble, not compacts, 13 and then, where would you do such a test? Because, as 14 I understand it, the High Flux Reactor is going to go 15 down in 2024 and they're having troubles with it. And 16 are you planning to go to Russia? Where would you do 17 such a test?
18 MR. TOMKINS: I don't know about Russia, 19 but --
20 So, the first question on the 21 qualification envelope, for the commercial reactor, 22 the particle power and the burnup are beyond the 23 limits we're holding ourselves to. So, we would, 24 presumably, have to do irradiation to address that.
25 MEMBER REMPE: And you're confident 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 because of what? What reason you won't have to do it 2 for Hermes, irrespective of Dave's concern? I'm just 3 wondering, did you need to have a validated computer 4 code to know you don't need to have it for Hermes?
5 MR. TOMKINS: Yes, but at the time we make 6 that judgment about whether we were within the fuel 7 envelope or not, we will have validated codes to 8 determine that.
9 MEMBER REMPE: Okay.
10 MR. TOMKINS: Or validated --
11 MEMBER REMPE: And the codes are? What 12 are the codes that are validated?
13 MR. TOMKINS: Well, we probably need 14 Brandon. Maybe you can help with that.
15 MR. LATTA: KP-BISON is our fuel 16 performance code. And so, part of this validation are 17 AGR-1 and AGR-2.
18 MEMBER REMPE: Okay. Part of it is, but, 19 then, I read the Topical Report, and I believe it's 20 even in our letter, that you plan to come back. Not 21 all the properties are well-defined for fully 22 validation. So, you are planning to get all the data 23 required to have that code validated before you go too 24 far in your licensing application? Or is it going to 25 be, I mean, it's a Construction Permit, so 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
27 1 ahead and build it, but you can't load the fuel. So, 2 you'll have to have data by that time to have the 3 validated code? I'm just kind of thinking about 4 this --
5 MR. HAUGH: I'm going to step in here.
6 This is Brandon Haugh, the Senior Director of Modeling 7 Simulation at Kairos. Thanks, Joy.
8 It depends on how you define validation, 9 right? So, we're defining validation within the 10 scopes of the predictability of the code to predict 11 the performance of our envelope, which is the AGR 12 envelope. We believe we have all the data to do that.
13 MEMBER REMPE: And is the staff onboard 14 with that assumption?
15 MR. HAUGH: They'll get a chance to review 16 that validation and concur, and that work is ongoing.
17 And they should get a chance to see that.
18 MEMBER REMPE: And so, we'll see the 19 validation, the fully validated Topical Report for 20 TRISO with KP-BISON before? Because I was just was 21 kind of going, well, nothing is going -- we've 22 discussed this before in our reviews of these Topical 23 Reports, the kind of preliminary reviews for the 24 methodology, but it's not totally -- or the approach 25 to the methodology. It's not a validated methodology, 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 even though you have an approved --
2 MR. HAUGH: Sure.
3 MEMBER REMPE: -- a staff evaluation that 4 concurred. And so, again, I just want to make sure 5 everybody understands that.
6 And then, what's the answer to the 7 question about the facility where you're going to be 8 doing these irradiations of the pebble?
9 MR. TOMKINS: That might be a closed 10 session.
11 MEMBER REMPE: Oh, okay. That sounds 12 good. Thank you. Don't let me forget.
13 MR. TOMKINS: Yes. Nicole, can you kind 14 of note that, so we pick that up during the closed 15 session?
16 MS. SCHLICHTING: Sure.
17 CHAIR PETTI: This is Dave. I just want 18 the court reporter to note that Matt Sunseri, Member 19 Sunseri, has also joined. Thank you.
20 MR. TOMKINS: All right. Next slide.
21 MR. LATTA: Yes. So, we're going to 22 definitely go through the methodology, talking about 23 the fuel pebble laboratory testing. These are tests 24 to demonstrate that the pebble meets functional 25 requirements. In addition to that, there's fuel 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 irradiation testing that we'll go into, and then, some 2 connections with fuel performance modeling, and then, 3 finally, the fuel surveillance program for the 4 reactor.
5 And next slide. Advance one more, please.
6 Okay. This slide just talks to the long 7 history of experience with TRISO fuel and matrix 8 materials and fuel forms that have been demonstrated 9 in the U.S. and through international experience. The 10 TRISO fuel form was first introduced for gas reactors 11 in the 1960s.
12 A lot of attention in this case was given 13 to the German pebble reactor designs and use of pebble 14 fuel, and then, in addition to that, more recently, 15 China has gone down this road of licensing and 16 starting to operate two high temperature gas reactors.
17 And then, within the U.S., there was the 18 General Atomics experiences with a couple of prototype 19 reactors and carbides fuel and prismatic core.
20 And so, there's quite a long history of 21 many nations being able to set up fuel fabrication and 22 demonstration through irradiation testing, operation 23 of prototypes or demonstration reactors, the 24 capability of this technology, fuel technology, to 25 work within a gas reactor.
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 And then, this kind of all culminates 2 within the U.S. through the AGR program, which built 3 on this extensive experience to develop a domestic UCO 4 TRISO coated fuel particle. And a large part of what 5 Kairos is proposing here leverages this DOE program 6 and the EPRI Topical Report on TRISO particles as a 7 foundational case for our fuel qualification.
8 Next slide, please.
9 MEMBER REMPE: This is Joy.
10 MR. LATTA: Yes?
11 MEMBER REMPE: Just on that, in the 12 Topical Report, I think there's a typo about the years 13 the THTR operated. So, you might want to fix that if 14 you're updating it at some point.
15 MR. LATTA: Okay. Thank you. We'll take 16 that down.
17 All right. This slide, it's a lot of 18 numbers, but the point of this slide is to talk to the 19 extensive amount of testing the DOE has been doing 20 with the AGR program.
21 And then, the bottom set of slides is a 22 comparison to German irradiation test data that was 23 also performed in test reactors. Whereas, the AGR 24 particles were tested as compacts, the German fuel was 25 tested in a pebble form. Historically speaking, 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
31 1 performance of German fuel had been considered kind of 2 the gold standard for excellent experience with TRISO 3 fuels, and then, the AGR program over the last many 4 years has been able to really demonstrate an 5 equivalence with that through the domestic testing 6 program.
7 So, this slide talks to the kind of 8 testing that was performed and the low failure 9 fractions that were demonstrated in the AGR program 10 and how that was then incorporated into the EPRI 11 Topical that was reviewed by the NRC and issued an 12 SER.
13 Then, next slide, please.
14 And then, to go on with that kind of data 15 we see in the literature and what has been done 16 recently with the AGR, there's also furnace safety 17 testing data with AGR compacts tested at a range of 18 temperatures of 1600 to 1800 C for hundreds of hours, 19 tens of thousands of particles tested between AGR-1 20 and AGR-2, showing fairly low failure rates and high 21 reliability of the TRISO particles.
22 In addition, historically, German fuel has 23 been tested under very similar conditions with UO2 24 TRISO particles but in pebble fuel form and, also, has 25 historically demonstrated excellent performance, 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 especially up to the 1600 C range.
2 Okay. Okay. So, switching gears towards 3 the PIRT, Kairos Power conducted a PIRT on the two 4 main parts of the fuel, which are the pebble and the 5 fuel particle, and then, broke it down by 6 subcomponents, the regions within the pebble, the 7 layers and parts of the fuel particle. The 8 application for this was our reactor and its thermal 9 and radiation conditions. The scenarios were 10 fabrication operations and accident conditions, and 11 the PIRT was performed to identify high priority 12 phenomenon that are related to the figure of merit, 13 which was fission product transport and release.
14 And so, there was an internal PIRT 15 performed in Kairos, and then, an external PIRT 16 performed with subject matter experts. And these are 17 kind of now the main results of the PIRTs. There's a 18 graph on the right which shows kind of the number of 19 high-ranked phenomenon we observed for TRISO or 20 pebbles. There was almost 200 phenomenon identified 21 over the course of this PIRT.
22 For TRISO, there's a lot of high-level 23 knowledge related to this now. So, the highest ranks 24 were Rank 2, where it's high importance, and medium 25 knowledge level. And then, for the fuel pebble, 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
33 1 saw much more diverse rankings, and these were mostly 2 related to the novel fuel design, manufacturing, and 3 performance of the annular fuel pebble.
4 Also to say that this PIRT really built on 5 this 2004 TRISO PIRT that was originally out there 6 kind as a foundation for starting this effort.
7 CHAIR PETTI: Ryan, just a point. If you 8 look at the date of that PIRT, 2004, that really 9 predates AGR.
10 MR. LATTA: Yes.
11 CHAIR PETTI: I think it was about a year 12 and a half in. And so, there were lots of things on 13 the table. I was in that PIRT. And if you reflect 14 back and look at everything from AGM back on that 15 PIRT, you probably would re-rank them significantly 16 differently. There were all sorts of issues that were 17 out there because of a lack of data that I think today 18 you would probably take some of them and rate them 19 lower in terms of their importance, given where TRISO 20 particles are today than they were in 2004.
21 MR. LATTA: Yes, and largely, what we did, 22 we took like the phenomenon, and then, we gave 23 everything brand-new ratings and rankings based on 24 present knowledge.
25 CHAIR PETTI: Ah, okay.
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 MR. LATTA: And, you know, we have a 2 different application --
3 CHAIR PETTI: Right.
4 MR. LATTA: -- a different scenario. You 5 know, the pebble and some other things are different.
6 So, things were re-rated and ranked to reflect that 7 difference.
8 CHAIR PETTI: Ah, good. Thanks.
9 MR. LATTA: Thank you.
10 MEMBER REMPE: So, this is Joy.
11 And when I was reading the Topical Report, 12 I thought there was just a single PIRT. And my 13 question had been, are they internal and expert 14 people? It never identifies who participated.
15 I think what you just said in your 16 presentation was that you had an internal PIRT, and 17 then, you had an external one? But you must have 18 combined the results somehow? Could you elaborate a 19 little bit more about who you hired to bring in and 20 their years of experience? And if you had a single 21 internal one, who all -- I mean, did you just take 22 everyone in your fuels branch, or how did you do this?
23 MR. LATTA: Yes. So, the internal PIRT 24 was performed by the subject matter experts at Kairos, 25 and then, later, we included a set of experienced 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 subject matter experts that were external, whether 2 academic or related to the National Laboratories, to 3 get their input. And this was combined into a report, 4 and then, that report was seen by the NRC.
5 MR. TOMKINS: We can probably give the 6 name.
7 MR. LATTA: Can we give the name?
8 MR. TOMKINS: Yes.
9 MR. LATTA: Okay. Okay. So, I can go 10 with a list of names. The PIRT process was 11 facilitated by Chris Lamm.
12 MR. D. GARDNER: Hey, Ron? Hey, Ron, this 13 is Darrell Gardner.
14 I think we need to, if we're going to be 15 mentioning names, we need to be doing that in closed 16 session.
17 MR. LATTA: Okay. We could save that for 18 the closed session.
19 MEMBER REMPE: That would be great. And 20 then, I guess if there is a report that actually has 21 the PIRT report, and you did share it with the NRC, 22 could we ask you share it with us?
23 MR. D. GARDNER: The PIRT was not 24 submitted on the docket.
25 MEMBER REMPE: Okay. So, we're not 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 allowed to see it?
2 But, yes, please share the names, then, in 3 a closed session.
4 MR. LATTA: Okay.
5 So, next slide, please.
6 Okay. And so, the objective of the PIRT 7 is to understand where you have high importance and 8 medium or low knowledge level, and there you know the 9 phenomena that you really need to investigate as far 10 as your fuel qualification program.
11 So, through that process, this slide just 12 talks to the main things that were found in the PIRT 13 that need to be addressed. And so, there were, 14 obviously, manufacturing/development-related issues 15 with the pebble, since this was conducted a few years 16 ago now, and the objective was that we would have 17 manufacturing/development, obviously, and be able to 18 leverage German and AGR program experience in that 19 process.
20 And then, for fuel qualification, 21 specifically, things related to the pebble and its 22 performance to meet functional requirements, there was 23 a series of mechanical and material compatibility-24 related phenomenon we would like to investigate. And 25 so, a fuel pebble laboratory testing program was 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 created to address those issues.
2 MR. BLEY: This is Dennis Bley.
3 Either you -- or it's really a question 4 for staff, or maybe Weidong can follow up -- if PIRT 5 was not submitted on the record, did the staff do an 6 audit and is there an audit report on the PIRT?
7 Weidong, you can follow up with the staff 8 later on that. We don't need to talk about it here.
9 MR. WANG: Okay. Will do.
10 MR. LATTA: Okay. Move on to the next 11 slide, please.
12 Okay. So, this slide talks to the 13 specification, manufacturing, and quality control.
14 So, the TRISO particle specification used 15 in our reactor is equivalent to the AGR in AGR-5/6/7 16 specifications. It largely draws from this and we're 17 trying to replicate the fuel that was generated and 18 used for AGR-2 as a way to leverage the irradiation 19 test data and the AGR-2 program and review of the EPRI 20 TRISO Topical. The TRISO specification draws on and 21 is similar to historic ACGR fuel pebbles with special 22 features, as we have discussed, for FHRs.
23 And then, discussing manufacturing, 24 kernels are fabricated through a sol-gel process to 25 create microspheres. Particles are coated through 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
38 1 continuous CVD process, and then, pebbles are formed 2 from a mixture of graphite powders and binders and 3 with incorporated TRISO fuel particles impressed in 4 the shape and heat-treated. So, these are kind of 5 traditional methods and forms of manufacturing that 6 have been used in the past, but apply to our specific 7 application.
8 And then, beyond that, is the inspection 9 of product to demonstrate that the product meets 10 compliance to the specification we previously 11 mentioned.
12 Next slide, please.
13 CHAIR PETTI: Ryan?
14 MR. LATTA: Yes?
15 CHAIR PETTI: A question. Why don't you 16 go back?
17 MR. LATTA: Sure.
18 CHAIR PETTI: The AGR-2 and 5/6/7 19 particles were enriched at a little over 14 for AGR-2 20 and I think a little over 15 for 5/6/7. Is that the 21 enrichment levels you are going to go with or are you 22 going to go up to the LEU limit?
23 MR. LATTA: Yes. No, we go up to the LEU 24 limit, and that's about the only real difference 25 between --
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 CHAIR PETTI: Right. And then, you're 2 going to try to get to complete burnup, if you will?
3 And that's what puts you out of, sort of in this --
4 AGR-1 went to those limits, but it was a small kernel.
5 These are bigger kernels than AGR-2, and that's where 6 you feel you may need testing for the --
7 MR. LATTA: Yes, yes. And so, we had 8 recognized that.
9 CHAIR PETTI: Yes.
10 MR. LATTA: And that is explained within 11 the Topical for the reasoning. And AGR-5/6/7 was the 12 larger particle, but it never reached to the 19-13 plus --
14 CHAIR PETTI: Right, yes.
15 MR. LATTA: So, we're sticking with AGR-2 16 now, which was also previously reviewed, as you know.
17 CHAIR PETTI: Yes. Okay.
18 MR. LATTA: Okay. Next slide, please.
19 Okay. This just talks of quality control.
20 There's a list of components of the particle and 21 pebble, and it kind of just lists the different kinds 22 of inspections that will be performed. There's a 23 significant amount of characterization and inspections 24 that are performed through the fabrication process to 25 demonstrate the product meets the specifications.
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 That's a very important part of fabrication, to 2 demonstrate and prove that the product meets the spec.
3 Okay. Okay. So, it addresses the 4 qualification envelope. So, for fuel operated in the 5 reactor, there are really four key parameters related 6 to fuel performance that we identified: power, 7 burnup, temperature, and fluence.
8 And so, operating under steady-state 9 conditions, there's an operating envelope, and then, 10 an envelope for temperature under transient 11 conditions. And so, in the Topical, what we proposed 12 in there has been that the qualification envelop is 13 really the AGR-2 irradiation conditions, as defined by 14 the TRISO Topical Report. As long as you're able to 15 demonstrate that you're operating within that 16 envelope, the fuel is qualified for these irradiation 17 conditions. If your reactor needs to operate outside 18 of those conditions, then you would need to collect 19 additional irradiation test data.
20 If you can advance to the next slide, 21 please?
22 And so, this is a table of the 23 qualification envelope and example conditions for the 24 Hermes non-power, and then, the KP-X Power Reactors.
25 On the right -- or excuse me -- on the left are 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
41 1 four parameters we have just discussed, and then, 2 temperatures, and also, temperatures below that for 3 postulated events. The first are for normal 4 operations. And so, the proposed qualification 5 envelope for normal operation matched conditions that 6 were observed in the AGR-2 irradiation.
7 And then, you need to go to the next 8 column which are examples of Hermes conditions. As 9 you can see, the temperatures, burnup power, and 10 fluences are less, and sometimes significantly less, 11 than the operating envelope.
12 And then, as you go to the right, you see 13 KP-X in the final column, the conditions are higher, 14 and some of them exceed -- specifically, power and 15 burnup and fluence is a little bit higher than the 16 operating envelope.
17 So, you can see there's a difference 18 between Hermes, which should be able to operate within 19 the operating envelope of AGR-2, while KP-X would be 20 outside of this operating envelope and require 21 irradiation testing.
22 Okay. So, moving on to a different part 23 of fuel qualification. This is the laboratory test 24 program. So, no irradiation involved in this case.
25 And so, the objective is to demonstrate that annular 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 fuel pebbles meet the functional requirements, and 2 this is through a series of mechanical-related tests 3 and material compatibility tests in a laboratory 4 environment.
5 Okay.
6 MEMBER REMPE: So, this is one where I'm 7 curious, I guess, along with what Ron was talking 8 about. I just really am wondering what the basis is 9 to know that radiation won't affect molten salt 10 infiltration with cracking. I know you're going to be 11 looking for cracking, but the depth of cracks, as the 12 pebbles are going in circulation. I just am wondering 13 if there's a good, strong basis for saying we don't 14 need to do testing to assess the combined effects.
15 MR. LATTA: Sure. So, you would less 16 expect cracks to open up with irradiation, more to 17 close with irradiation indensification. The fluences 18 are fairly low, especially for Hermes, going in.
19 Infiltration is more related to the width of the pore, 20 or I guess in that case it could be a crack, the crack 21 width. But you would need to also infiltrate a 22 significant amount of Flibe coolant to lose buoyancy.
23 MR. TOMKINS: Right. And the Chinese 24 casting showed that you didn't have infiltration up 25 to, I think it was 600 kilopascals. And 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
43 1 operating at 200. So, we've got that background as 2 well.
3 MR. LATTA: Yes.
4 CHAIR PETTI: So, can I just ask, in terms 5 of the testing, particularly on the compatibility and 6 the infiltration, will you use sort of a tech spec 7 limit of impurities? You know, in a lot of these 8 systems I know that the chemical compatibility of 9 graphite with air and steam is strongly dependent on 10 impurities that are present in the graphite. And so, 11 I could imagine that the impurities might have an 12 effect.
13 MR. LATTA: Yes, I think for material 14 compatibility, if you think back to MSRE, where the 15 fuel was dissolved into the Flibe, and you had a whole 16 series of fission products and other transition metals 17 and materials from the structurals, you still didn't 18 see degradation of graphite or graphitic materials in 19 Flibe, and that, thermodynamically, and the way we 20 plan to run this reactor with fairly clean salt, that 21 we would not expect to see much interaction at all 22 between graphite and Flibe.
23 CHAIR PETTI: Since we're here on 24 compatibility -- and you can decide to answer in the 25 closed session -- I am concerned about some 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
44 1 stuff that will be corroded out of the steel by the 2 salt. And, in essence, you've set up a chemical pump, 3 right? There's an equilibrium concentration at the 4 hot end and an equilibrium concentration at the cold 5 end, and you'll get some Delta T mass transfer, and in 6 between the hot and the cold is this large pebble bed 7 with a huge amount of surface area. And what I'm 8 worried about is the iron-chrome-nickel in the salt 9 getting into the pebble and attacking the silicon 10 carbide.
11 Iron, chrome, and nickel, as you probably 12 are aware, must be as far away from this fuel as 13 possible. In a gas reactor, the closest of that is 14 the Kobel, and it's in a solid state, very far away 15 from the fuel.
16 If you've read some of the AGR-2 papers, 17 you'll find that a thermocouple wire -- a thin, tiny 18 thermocouple wire -- attacked silicon carbide, and 19 that was a nickel wire.
20 You can go and read the literature, that 21 there is strong chemical interactions between iron, 22 chrome, and nickel and silicon carbide. And you're 23 going to operate for, you know, thousands of hours 24 with a certain concentration in the salt that could be 25 picked up by the pebbles and could attack the silicon 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 carbide.
2 It would seem to me, since you mentioned 3 you were going to make some surrogate pebbles, that 4 you could test this in a Flibe loop -- you wouldn't 5 have to have a uranium-containing pebble -- and see 6 what sort of interactions you would actually get.
7 MR. LATTA: Yes. So, I completely 8 understand this concern. And there's a number of 9 barriers between Flibe, you know, Flibe on the 10 exterior that might contain transition metals and 11 Flibe getting into the silicon carbide layer.
12 First off, there would have to be 13 infiltration of the Flibe into the fuel region, which 14 is separated by the fuel-free region in the pebble.
15 So, your pressure would have to get fairly high.
16 Operating pressures are below 200 kPa, and as far as 17 we know, infiltration should begin above 600 kPa. So, 18 there's a pressure that would have to drive Flibe into 19 that region.
20 Secondly, if the Flibe got into the fuel 21 region, you would still have OPyC protecting the 22 silicon carbide, and then, if that barrier were not 23 there, you would still have to have an exchange of 24 Flibe-containing transition metals to feed a reaction.
25 So, there's a number of barriers that are in place 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
46 1 prevent this kind of a reaction.
2 MR. TOMKINS: Also, we're inspecting 3 pebbles every 50 days or so. We could see --
4 CHAIR PETTI: Well, you're not going to be 5 able to see the silicon carbide.
6 MR. LATTA: But you might be able to --
7 there's a potential opportunity to determine if Flibe 8 could be getting into the pebbles that are inspected.
9 CHAIR PETTI: Yes, we had all these same 10 arguments in AGR, and I'll just tell you that the 11 program thought that thermocouples 3 millimeters away 12 -- there was graphite between the thermocouple and the 13 compact, and there was overcoat between the compact 14 and the powder coats, and the nickel got there. Okay?
15 So, I understand all these technical 16 arguments for barriers, but chemistry is funky stuff.
17 MR. LATTA: Yes.
18 CHAIR PETTI: And the chemical potential, 19 those transition metals want that silicon carbide, and 20 they seem to make it there.
21 MR. LATTA: Yes. We're also at a lower 22 temperature, which also --
23 CHAIR PETTI: I understand that. Yes, we 24 don't know the kinetics. You know, it hasn't been 25 studied systematically or anything. But --
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 MR. LATTA: Sure. Okay.
2 MEMBER REMPE: So, to follow up on your 3 response about the Chinese data, talk to me more about 4 the Chinese data and what they obtained. You're just 5 talking about their pebble bed reactor, which used 6 helium as the coolant, right?
7 MR. LATTA: No. We're talking about five 8 infiltration tests. There's an ASTM standard for 9 molten salt infiltration testing and the structural 10 graphite and carbon matrix material. And so, as part 11 of this laboratory test program, we have a setup to 12 perform an experiment according to this ASTM standard.
13 And Oak Ridge researchers have been trying 14 to also perform these tests with, I believe, Flibe and 15 Flinak on a series of structural graphites and carbon 16 matrix materials. And they've been able to 17 demonstrate at what pressures you reach a threshold 18 for infiltration of salts into the porosity of these 19 graphites.
20 MEMBER REMPE: Okay. So, this was just 21 part of their molten salt program, not the program 22 that was discussed earlier on slide 14?
23 MR. LATTA: No. And Oak Ridge has also 24 been doing this kind of work. They have a setup in 25 Oak Ridge to perform these kinds of tests. And now, 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 we have a setup here to do this as well.
2 MEMBER REMPE: Okay. Thank you.
3 MR. LATTA: Yes. Thank you.
4 Next slide, please.
5 Okay. So, this slide just talks to the 6 type of mechanical and anthropology testing that's 7 been performed. The objective is to demonstrate that 8 pebbles do not fracture from static or dynamic loads 9 in the reactor, and that wear is accept over the 10 pebble's lifetime.
11 And so, there is compression testing, 12 crush tests to demonstrate the load at which a pebble 13 would fail. There's impact testing. So, cyclic 14 impact tests to demonstrate when a pebble might 15 fracture or chip. And then, tribology testing that 16 measures the wear rate in different environments and 17 under different loads and the coefficient of friction.
18 Okay.
19 MEMBER REMPE: Again, wouldn't you expect 20 that pebble fracture would occur much more easily 21 after it had been irradiated?
22 MR. LATTA: The data actually shows the 23 strength increases with irradiation and with the 24 temperature.
25 MEMBER REMPE: So, what about brittleness?
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 MR. LATTA: The load is increased -- the 2 allowable load increases with temperature and 3 irradiation. The load results in fracture. They're 4 fairly comparable. You know, you see about 2 to 3 5 millimeters of displacement before fractures. It's 6 generally been observed in these pebbles, whether 7 irradiated or not.
8 MEMBER REMPE: Okay.
9 MR. LATTA: They're porous. So, they kind 10 of crush a little bit before they fracture.
11 MEMBER REMPE: Okay.
12 MR. LATTA: Okay. And then, going on, 13 there's Flibe infiltration and buoyancy testing. So, 14 this is where you put a pebble, as we previously 15 explained, you put a pebble in a bath of Flibe under 16 pressure at temperature and you measure its weight 17 change before and after the test to investigate when 18 and under what condition or pressure you would see 19 Flibe infiltrate into the pebble. As I said, these 20 tests have been previously performed by Chinese 21 researchers and at Oak Ridge.
22 The test is really a mechanical test, but 23 there's also a Flibe compatibility portion of that 24 test, where you might run the test for thousands of 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> to demonstrate interaction between the carbon 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 matrix material and the Flibe salt.
2 The other compatibility test is with air, 3 and in this case, we're looking at oxidation rate of 4 the matrix material under a range of temperatures from 5 400 to about 700 C. And you're measuring mass loss 6 with time to create an equation to demonstrate that, 7 first of all, the pebble under normal conditions 8 should not interface with oxygen. It should be 9 largely in an inert environment. But, under safety 10 conditions, you could be concerned with oxidation with 11 overt air into the system.
12 CHAIR PETTI: Ryan, you probably know, but 13 there has been data developed under, I think, 14 university grants at DOE looking at oxidation of 15 matrix material with air. So, it would be a nice 16 comparison.
17 MR. LATTA: Yes, thank you. And that's 18 all we're trying to do, is demonstrate equivalence of 19 our materials with existing data or use a model.
20 CHAIR PETTI: All right.
21 MR. LATTA: Okay. And then in the topical 22 we have defined acceptance criteria for each of these 23 tests related to specific parameters. These are kind 24 of the non-proprietary definitions of the acceptance 25 criterias. So for mechanical testing of compression 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 impacts it's really about demonstrating that the 2 loads within your reactor system are allowable 3 compared to the data you've collected. For tribology 4 it's about wear rate to demonstrate that the outer 5 fuel- free zone of the pebble is adequate to prevent 6 mechanical interaction of TRISO particles out -- with 7 something outside of the pebble.
8 Next slide, please? Going down the list 9 there's the buoyancy testing, so about density and 10 whether there's Flibe infiltration or not and then 11 material compatibility related to interaction of Flibe 12 or air with the pebble and demonstrating that there's 13 -- what damage might occur or that you're preventing 14 damage under normal operation.
15 Next slide, please? Okay. So this slide 16 talks to irradiation testing. So when we looked at 17 the fuel operating envelope we discussed if you were 18 inside AGR-2 irradiation conditions would be 19 acceptable, but if you were outside of that you would 20 need to perform an irradiation test. So this part of 21 the methodology defines what that irradiation test 22 would be. It would be irradiation of fuel pebbles or 23 fuel pebble design with -- in a non-KP-FHR facility, 24 very similar to the AGR irradiation test with fission 25 product measurement and PIE to determine particular 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 failure fractions. And then we defined an acceptance 2 criteria for the particle failure fraction that would 3 result in what we consider high-quality fuel for use 4 in FHRs.
5 Okay. This slide talks to fuel 6 performance and the models that interface with either 7 analysis or data we've collected. KP-BISON, as you 8 know, is our main fuel performance model for analyzing 9 normal operation and transience, so this is connected 10 to the AGR validation. We performed an irradiation 11 test that -- we would also be validating this model to 12 that irradiation test. Additional model interfaces 13 are the modeling of the pebble bed. This informs wear 14 behavior and loads in the bed. And then the final is 15 finite element modeling of a pebble where we could 16 examine temperatures or mechanical behavior of the 17 pebble.
18 Okay. Fuel surveillance program. So with 19 the rest of the program completed and your -- get your 20 operating license and you're operating your reactor 21 there would be a fuel surveillance program to confirm 22 fuel performance in Hermes. And so the three 23 components of this program are fissure product 24 monitoring first to cover gas and Flibe coolant.
25 Then there's the PHHS, which is the pebble 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 handling and storage system. There will be an 2 inspection system that checks for burnup and examines 3 the physical condition of the pebble. And this 4 happens as the pebble -- the pebble goes through the 5 core multiple times, up to on -- well, up to an 6 average around six times through the core. So each 7 time it goes through it would go through this PHHS 8 inspection process.
9 And then finally there would be post-10 irradiation examination of pebbles from Hermes and 11 then the initial commercial reactor. And key things 12 would be examining our -- the TRISO particle failure 13 fractions, the amount of wear on the pebble surface 14 and whether we're seeing any amount of molten salt 15 infiltration into the pebbles after they have reached 16 their equilibrium burnup end conditions.
17 CHAIR PETTI: Ryan, go back for a minute.
18 MR. LATTA: Yes?
19 CHAIR PETTI: You guys may have done some 20 modeling on this, but the sorptivity of the cesium and 21 strontium in the graphitic matrix is very strong and 22 the Flibe coolant may not see significant changes in 23 those two isotopes' concentrations if something were 24 happening where the silicon carbide was degrading and 25 you didn't know it. It would be interesting; and you 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 can model all this, because I think you guys have to 2 tools, to see what a step increase in release of 3 cesium would mean in terms of transport through the 4 pebble and the coolant and can you see a significant 5 increase in the concentration of the coolant?
6 I've not looked at the chemistry, but it 7 is something to -- worth noting as you're thinking 8 about setting up limits and the like.
9 MR. LATTA: Thank you for that comment.
10 CHAIR PETTI: So let me here -- before you 11 go to summary, let me talk about my other concern.
12 I think you and I have different 13 definitions of fuel qualification. Your definition is 14 necessary for sure, but I don't think it's sufficient.
15 The irradiation proof testing is at the heart of every 16 TRISO program worldwide.
17 The Germans did it for pebbles called HFR 18 K5 and K6. Well after pebbles were being irradiated 19 in AVR they did these tests at Petten.
20 The Japanese took their compacts, tested 21 them in a reactor in Japan. Wasn't a really strong 22 reactor, so they came out to Oak Ridge and tested at 23 the HFIR.
24 The Chinese irradiation-proof tested the 25 pebbles they made in Russia for their 10 megawatt test 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 reactor at Beijing and then subsequently irradiated 2 tested -- proof tested pebbles off the production line 3 for the pebble bed that's in commercial operation.
4 And of course the U.S., that's what AGR-5 5/6/7 in the DOE Program is about.
6 And the reason for the proof testing is 7 because specs aren't perfect and you never know 8 everything. And that's why you do these things. And 9 there's tons of history across fuel development 10 programs beyond TRISO where people made, quote, small 11 changes and it had a deleterious effect on the fuel.
12 I would say that this pebble is unique.
13 I know that the topical report says it's like a German 14 pebble. I find it very different in a lot of 15 different ways. The free zones, the high packing 16 fraction, and the pressure that you'd have to press a 17 pebble is much, much higher than when you press a 18 compact.
19 And that plus the fact that the QC may not 20 catch everything in my mind suggests that there needs 21 to be irradiation testing, not that it has to be 22 completed before you're operating Hermes, but that if 23 you were sure that the burnup and fluence stayed ahead 24 of what was in Hermes, you'd at least have some 25 indication that this process of making pebbles out 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
56 1 production scale you didn't bring something in that 2 you didn't foresee in the manufacture and that wasn't 3 captured by the QC.
4 MR. TOMKINS: Could we respond to that, 5 David? That was a good comment.
6 CHAIR PETTI: Sure.
7 MR. HACKETT: David, this is Micah 8 Hackett. I'll take a part of that at least. We 9 recognize that if we were to press spherical pebbles 10 in the same way in which for example the German 11 program pressed them, yes, very high pressures would 12 be needed to press those pebbles. So we have 13 developed an alternate method of being able to press 14 pebbles. And we're going to be using a hot press 15 process instead of a cold process.
16 What that means is we use far less force and 17 being able to press our spherical compacts. So that 18 should, we believe, that greatly diminishes the amount 19 of energy needed to press that pebble and also should 20 prevent damage to the TRISO particles.
21 22 CHAIR PETTI: So you're going to -- the 23 resin will activate in the pressing?
24 MR. HACKETT: Correct.
25 CHAIR PETTI: Is it hot pressing or is 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
57 1 warm pressing? Do you know the different --
2 MR. HACKETT: Yes.
3 CHAIR PETTI: I mean I don't want to get 4 into proprietary, but --
5 MR. HACKETT: Yes, maybe let's talk about 6 it more in the proprietary session.
7 CHAIR PETTI: Okay. Yes. Yes.
8 MEMBER BALLINGER: Yes, this is Ron 9 Ballinger. I thought about this also, but I'm 10 struggling whether I would consider the differences 11 that might -- that we see a potential safety risk or 12 a commercial risk. And so I haven't decided whether 13 I think that's true, but isn't that the question that 14 we're talking about here? If it's simply a commercial 15 risk, well, some days chicken, some days feathers.
16 But if it's a safety risk, that's a whole different 17 ball game. And I guess I would certainly defer to 18 Dave's judgment there because he has all the 19 experience.
20 MR. TOMKINS: So, Dave, I think you said 21 that if we were to do an irradiation program, it might 22 not be needed for Hermes, but it would be needed for 23 APX, the power reactor. Is that what you said?
24 CHAIR PETTI: No, I said that you didn't 25 have to have the irradiation complete to get 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
58 1 operating license, that you just had to have the 2 irradiation stay ahead of where you were in the 3 reactor itself.
4 MR. TOMKINS: All right. Because the test 5 reactor is obviously a test reactor, right, or you 6 know, it's to test things. And certainly that can be 7 a foundation for what we do in the commercial reactor, 8 which is coming to come behind it.
9 CHAIR PETTI: Right.
10 MR. LATTA: Additionally versus a gas 11 reactor we have the FliBe coolant as a containment 12 outside of the fuel itself.
13 MR. TOMKINS: Right, which is a 14 significant difference. The other thing is our margin 15 to any kind of limits is very large. I mean we are 16 way far away from the 1,600 for transient and from the 17 1,360. So --
18 CHAIR PETTI: Yes, I'm not at all worried 19 about a performance issue. I'm worried about 20 particles failing in PIE that were unanticipated 21 because of something done in fabrication that was 22 missed.
23 So I mean, if you go back through and you 24 read the EPRI Topical Report, they'll talk about what 25 happened in the new production reactor program. 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
59 1 I can tell you that the vendor swore up and down it 2 was not their fuel that caused the massive failures in 3 those irradiations until they happened at both Idaho 4 and Oak Ridge. And then it was oh, it wasn't those 5 guys doing the irradiation. It was us who made the 6 fuel. And they still couldn't figure out what they 7 did until PIE was performed. And it was subtle. They 8 had made changes and were convinced that it wouldn't 9 make any difference.
10 This is the same argument as saying an 11 accident-tolerant fuel where I'm going to change 12 either the fuel pellet or the cladding in some minor 13 way and I don't have to irradiation test it and yet 14 they are being irradiation tested. I mean that's just 15 sort of like the first commandment of fuel behavior, 16 people.
17 MR. BLEY: Well, this is Dennis Bley.
18 And, Dave, I certainly don't have your expertise in 19 the fuels area, but it's not just the golden rule of 20 fuels. All across technology there are so many cases 21 of places where we designed a new system specifically 22 to solve a problem in an existing one and yet when we 23 put it into service it probably did solve that 24 problem, but new ones were introduced. And the idea 25 that you don't need testing because you haven't 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 thought of what's going to go wrong is just not 2 comforting.
3 MR. TOMKINS: Well, it's not that we're 4 not doing testing, because there's been a lot of 5 testing of the particles and there's separate testing 6 of a pebble. But you're right, as an integrated 7 entity we're not doing irradiation testing.
8 CHAIR PETTI: Right. I mean I completely 9 agree with much of the documentation about the 10 positives that the two technologies bring, but when 11 you bring two technologies together, besides bringing 12 the positives, you can potentially bring some 13 negatives. And just thinking in that failure space is 14 what I think Dennis and I are both talking about.
15 MR. TOMKINS: Okay. Next slide. I think 16 the last couple are mine. So I'm just going to click 17 through these. We kind of covered these, but there's 18 50 years of operating and testing experience on these 19 p a r t i c l e s c e r t a i n l y .
20 We did a PERT and we implemented actions to 21 address the PERT. The manufacturing and inspection of 22 the fuel will be to a spec that ensures that it's 23 equivalent to what was tested in AGR-2. We're also 24 going to meet the conditions in the TRISO Topical 25 Report. I think there's five conditions 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
61 1 limitations in that report, so we will have to make 2 sure that our fuel meets those conditions. We're 3 going to operate well within a defined set of fuel 4 qualification limits during both normal and licensing 5 basis events.
6 Next slide? We will do irradiation 7 testing if the TRISO particle is going to operate 8 outside of AG-2, which might be needed for the 9 commercial reactor. We have a surveillance program 10 that confirms that the pebble form is not adversely 11 impacting fuel particles. We can talk a little bit 12 about this in the closed session, but we're going to 13 take a camera shot of these pebbles that come through.
14 And so if the wear is through and particles are 15 exposed, we would know that. And then we have the 16 ability to examine pebbles as they -- oh, I just 17 mentioned that. And we're also going to do PIE on 18 both the test reactor and on the commercial reactor.
19 Of course that's obviously after the fact.
20 Next slide?
21 CHAIR PETTI: So, Jim, just a question:
22 Are you also planning on potentially taking a pebble 23 out before it reached its full burnup, if you will, 24 and do PIE? So you'd have them at 25 percent, 50 25 percent, and 75 percent?
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 MR. TOMKINS: Hadn't really thought about 2 that, but you wouldn't get the burnup of course.
3 CHAIR PETTI: Right, but you'd get sort of 4 a characterization, if you will, one-every-so-often-5 sort of thing.
6 MR. TOMKINS: That isn't currently part of 7 our plans, but --
8 CHAIR PETTI: Yes.
9 MR. TOMKINS: So conditions. Joy, did you 10 have a question?
11 MEMBER REMPE: Yes, it's something I 12 forgot to ask earlier. If this is a good time to have 13 a detracting question, on slide 31 on the material 14 compatibility, it has Flibe -- the acceptance criteria 15 is Flibe interaction with the pebble does not result 16 in damage to the fuel region of the pebble. How do 17 you define damage? Does that mean if you see any 18 Flibe ingress into the fueled region? So it goes past 19 the unfueled region into that region, you'll stop and 20 say we got to stop here, folks, we've got a problem?
21 Or does it have -- is there something more significant 22 than ingress? And if it's just ingress or 23 infiltration, then why don't you say Flibe 24 infiltration into the fueled region of the pebble?
25 MR. LATTA: We're looking for -- what 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 you're looking for would be like degradation, so 2 microstructural changes that could impact either heat 3 transfer or the mechanics of the pebble and break down 4 from expected -- what we expect of the material. So 5 it would be --
6 MEMBER REMPE: It's going to be a harder 7 thing if you -- I mean one, you ought to be specific 8 and say okay, I want to do testing to see if it 9 adversely affects heat transfer in the fueled 10 region --
11 MR. LATTA: Yes.
12 MEMBER REMPE: -- or material properties.
13 MR. LATTA: Sure.
14 MEMBER REMPE: Or an easier criterion to 15 have is the acceptance criteria is that you don't have 16 Flibe ingress into the fueled region.
17 MR. LATTA: Yes.
18 MEMBER REMPE: I mean, you can do that if 19 you want to, but then okay, how much degradation in 20 the heat transfer? I mean, this is a very vague 21 criterion in my opinion and so I think you ought to be 22 more specific. And the easiest way to deal with that 23 would just say ingress into the pebbled fuel region.
24 MR. LATTA: Yes. Well, then the 25 expectations that really see -- is not to observe 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 anything occurring because these materials have been 2 shown to be highly compatible and they're 3 thermodynamically compatible. And there's been a lot 4 of experience in the other tests and in the MSRE to 5 show that graphite is compatible with Flibe. So we're 6 just really kind of trying to confirm that when we use 7 our materials that we see this same history of 8 compatibility between the materials.
9 MEMBER REMPE: So again, I lobby for you 10 ought to just say ingress to confirm what you've seen 11 elsewhere unless you want to try and go further. And 12 if you want to go try --
13 MR. LATTA: Yes.
14 MEMBER REMPE: -- and go further, then 15 please be specific so we know what it is.
16 MR. LATTA: Sure.
17 MR. TOMKINS: Okay. So I'm just going to 18 close with the limitations. So we have some 19 limitations we've put on ourselves. And we also have 20 one that was in the NRC's SER.
21 The first limitation is that this 22 methodology only applies if the design is described in 23 Section 112 and you have Flibe that's maintained.
24 We have to demonstrate that the operating 25 conditions and the safety analysis conditions 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
65 1 within the qualification limits that we've specified 2 in table 3-11 of the report.
3 If we're going to extend that envelope, then we 4 have to do an irradiation program. We also have to 5 meet the limitations and conditions in the EPRI TRISO 6 Topical Report, which I previously mentioned that.
7 There's a couple of conditions that we 8 have to meet for the power reactor, and that is we've 9 got to provide additional justification on the 10 applicability of this methodology during rapid 11 transience and additional justification that Flibe 12 does not inversely impact irradiated fuel pebble 13 buoyancy.
14 And then this methodology only applies to 15 a design with a safety-related positive flux rate 16 trip. And then the NRC has added SER limitations to 17 justify the applicability of this methodology to a 18 test reactor for rapid transients. That's it.
19 CHAIR PETTI: Members, questions?
20 Okay. Then I guess who from the staff is 21 going to be presenting?
22 MR. VAN WERT: That will be me. This is 23 Chris Van Wert.
24 CHAIR PETTI: Hi, Chris.
25 MR. VAN WERT: Hey, how are you doing?
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 CHAIR PETTI: Okay.
2 MR. VAN WERT: So do we jump into it now?
3 I didn't --
4 CHAIR PETTI: Well, I was just going to --
5 I'm sitting -- how many slides do you have?
6 MR. VAN WERT: It is -- one second -- I 7 believe it's about 10 or 11, somewhere around there.
8 CHAIR PETTI: Well, why don't we take a 9 10-minute break then and we'll come back at half past 10 the hour?
11 MR. VAN WERT: Sounds good.
12 CHAIR PETTI: Thanks.
13 MR. VAN WERT: Thank you. So, okay, 3:30 14 your time? Okay.
15 MEMBER REMPE: And the slides from the 16 staff are now open slides, is that true? They were 17 given to us --
18 MR. VAN WERT: Correct.
19 MEMBER REMPE: Okay. Thank you.
20 MR. VAN WERT: And I will share/control 21 them, so --
22 (Whereupon, the above-entitled matter went 23 off the record at 3:20 p.m. and resumed at 3:30 p.m.)
24 CHAIR PETTI: Okay. We're back in.
25 Chris, it's yours.
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. VAN WERT: All right. I'm going to go 2 ahead and share the slides, so give me one second.
3 (Pause.)
4 MR. VAN WERT: All right. Is that visible 5 to everyone okay?
6 CHAIR PETTI: Yes, looks good.
7 MR. VAN WERT: So I will also say before 8 we start here that I will not be able to see -- while 9 sharing it I can't see the rest of the screen from the 10 Teams meeting, so I am asking the other NRC members to 11 keep an eye out for any raised hands and to speak up 12 and let me know if there's a question. Also any of 13 the members, please feel free to just speak up during 14 the presentation as well, but we will continue on that 15 then. And like I said, feel free to speak up at any 16 time.
17 All right. Are we ready to start then?
18 CHAIR PETTI: Yes, go ahead.
19 MR. VAN WERT: Okay. So good afternoon, 20 everyone. My name is Chris Van Wert and I'm a senior 21 reactor systems engineer in Technical Branch 1 of the 22 Division of Advanced Reactors, Non-Power Production 23 and Utilization Facilities. I will be presenting the 24 staff's review of Kairos' topical report, Fuel 25 Qualification Methodology for the Kairos Power 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 Fluoride Salt-Cooled High Temperature Reactor, 2 Revision 2.
3 So Kairos requested the staff's review and 4 approval of the topical report which provides the 5 methodology for qualifying the Kairos fuel pebble 6 design for either a power or non-power version of the 7 KP-FHR. The staff's review is focused on the overall 8 fuel qualification of the framework -- fuel 9 qualification framework which includes but not limited 10 to the use of existing data, unirradiated testing, 11 irradiation testing, and surveillance.
12 It's important to note that the topical 13 report is applicable to both non-power tests and power 14 versions of the KP-FHR, as we've mentioned already, 15 and the staff considered this in the review.
16 Also, this topical report does not 17 directly present any fuel performance code updates for 18 staff review and approval, but is instead focused on 19 the methodology itself to support fuel qualification.
20 That being said, the data obtained from the fuel 21 qualification process can be used in future 22 performance code updates, but that is not covered 23 directly as part of this topical report or the staff's 24 review.
25 Just quickly, the regulatory basis for 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 fuel qualification framework is -- includes 10 CFR 2 50.34(a) and (b), 10 CFR 50.43(e), and the 3 corresponding regulations for design certifications, 4 COLs, and standard design approvals in 10 CFR Part 52.
5 The licensing basis also includes 10 CFR 100.11.
6 Additionally Kairos Power's PDC 10 and PDC 16, which 7 were previously approved by the staff in Topical 8 Report KP-TR-003MP-A, are also part of the licensing 9 basis.
10 So the first discussion topic I wanted to 11 cover you just heard about in Kairos' presentation, 12 but this is the applicability of the existing data.
13 And the Kairos Power fuel qualification methodology 14 builds upon the approved topical report on TRISO fuel 15 particle qualification, EPRI-AR (NP)-1. This was a 16 topical report submitted by EPRI in coordination with 17 INL to provide TRISO particle testing data and 18 qualification from the AGR-1 and 2 campaign.
19 This topical report serves as a fuel 20 qualification for TRISO fuel particles as long as it's 21 within the fuel specifications and operational 22 conditions defined by the AGR-1 and 2 Program.
23 Additional existing data related to carbon 24 matrix property data was used to inform Kairos' 25 testing plans to support fuel qualification.
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 The staff reviewed the Kairos fuel 2 particle specifications in comparison with the AGR-1/2 3 campaign and finds that the Kairos particle 4 specifications are consistent with the AGR-2 TRISO 5 test particles and therefore the data is applicable to 6 the Kairos particle design up to the test conditions 7 investigated as part of AGR-2.
8 Additionally the staff finds that the carbon 9 matrix property data is acceptable for informing the 10 test conditions as used in the topical report.
11 In Section 3.6 of the topical report 12 Kairos presents their planned fuel pebble laboratory 13 testing and it will be used to obtain Kairos' fuel 14 pebble data in support of fuel qualification. And 15 this includes mechanical tribology, buoyancy and salt 16 infiltration, material compatibility.
17 The staff reviewed the pebble test to 18 confirm that the testing conditions chosen would bound 19 those experienced by the fuel pebbles in reactor 20 conditions and that the testing methods either 21 followed an established method or were appropriate for 22 obtaining the desired data. The staff found the fuel 23 pebble testing as presented in Section 3.6 of the 24 topical to be acceptable for determining Kairos' fuel 25 pebble characteristics to support fuel qualification.
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 Section 3.7 of the topical report 2 addresses planned irradiation testing to support 3 operation of TRISO particles outside of the AGR-2 4 operational envelope if desired. I said a little bit 5 about that earlier that there's a certain box that the 6 AGR program kind of gave them an area to start with.
7 And Hermes fits within that, however the desired power 8 reactor version goes beyond that. So the irradiation 9 testing does include fuel pebble irradiation in a gas 10 environment, purged gas monitoring for fission gas, 11 and post-irradiation examinations.
12 The staff reviewed the description of the 13 irradiation test plans as presented in Section 3.7 and 14 notes that similar to the EPRI-AR (NP)-1 TRISO 15 particle fuel qualification topical report the 16 methodology uses sweep gas monitoring to initially 17 determine the release rate to birth rate ratio of 18 gaseous fission product releases from the test levels, 19 which is then followed by PIE. The non-destructive 20 PIEs include visual examinations, dimensional 21 measurements and gamma-spectroscopy to identify gross 22 external damage and burnup as well.
23 The Kairos power fuel qualification 24 methodology also includes destructive PIEs of a 25 limited number of test pebbles. This destructive 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 examination includes using the DLBL technique to 2 quantify fuel particle failure fraction. These DLBL 3 results can't results can't be used -- can be used to 4 confirm the failure fraction calculated by measuring 5 fission gas release during the irradiation test.
6 Staff finds that the irradiation testing 7 presented in Section 3.7 is closely related to the 8 previously approved topical report EPRI-AR (NP)-1 and 9 is acceptable for determining irradiated fuel failed 10 particle fraction and gross double behavior which 11 could impact behaviors of operation outside the bounds 12 of the AGR-2 test conditions.
13 Section 3.8 of the topical report 14 addresses fuel particle performance modeling and 15 discusses how the data collected from the fuel 16 qualification program will be used to inform and 17 improve fuel performance models. The staff's approval 18 of this topical report is related to the fuel 19 qualification methodology by which Kairos' fuel pebble 20 can be qualified. The staff further finds the data 21 collected while implementing the fuel qualification 22 methodology is acceptable for use in updating the 23 Kairos fuel performance model KP-BISON, however the 24 staff's approval of the fuel qualification topical 25 report does not approve a priori any modifications 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
73 1 the fuel performance model itself beyond whatever is 2 allowed by the staff's approval of the KP-BISON.
3 Section 3.9 of the topical report 4 addresses fuel surveillance plans for the initial test 5 and power KP-FHR cores which are used to both monitor 6 fuel performance and to collect data for fuel 7 performance codes. The fuel surveillance plan 8 includes cover gas monitoring, non-destructive 9 examinations, and destructive examinations.
10 Again the staff reviewed the surveillance 11 plans as presented in Section 3.9 and finds that, one, 12 the use of cover gas monitoring is an acceptable means 13 for measuring in real time any unexpected gross 14 failures of particles which could lead to an increase 15 in fission gas inventory in the cover gas.
16 Two, the non-destructive visual 17 examination methods are acceptable for determining if 18 a pebble has wear or other damage sufficient enough to 19 potentially impact the TRISO particles.
20 Three, the use of gamma-spectroscopy --
21 spectrometry is acceptable for determining burnup 22 levels to determine if the pebbles can be reinserted 23 into the core or should be instead sent to storage.
24 Four, the DLBL destructive examinations 25 are acceptable for confirming the failed fuel particle 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 fraction as seen in the sweep gas measurements.
2 And five, the destructive examinations are 3 also acceptable for confirming the wear and Flibe 4 infiltration separate effects test results.
5 Staff limitations. In addition to the 6 fuel qualification methodology limitations provided --
7 oh, yes?
8 Sorry. I thought I heard someone.
9 So in addition to the limitations that 10 were presented by Kairos within their topical report 11 the staff has the following limitation as well: And 12 that's that future license applications for non-power 13 KP-FHRs will include justification for the 14 applicability of this methodology during rapid reactor 15 transient events.
16 This limitation was intended to cover a 17 gap in that the topical report only directly addresses 18 rapid reactor transient events for power reactors in 19 the Kairos limitations. And this is because the 20 Hermes application addresses this issue directly in 21 its PSAR, so this limitation was not perceived 22 initially as being necessary in this topical report.
23 However, the staff decided to include this limitation 24 in its approval since the topical report addresses 25 non-power test reactors in general and not just 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 Hermes. The staff limitation on the approval 2 therefore covers all of any potential non-power KP-3 FHRs.
4 CHAIR PETTI: So, Chris --
5 MR. VAN WERT: Yes?
6 CHAIR PETTI: -- let me just understand.
7 You're basically saying that the qualification doesn't 8 include reactivity testing? Is that correct?
9 MR. VAN WERT: Correct.
10 CHAIR PETTI: Okay. But I thought the 11 licensee went through some very good discussions about 12 the response of their system to reactivity events.
13 You guys just didn't accept it because it wasn't 14 validated, or you just didn't accept it -- I'm trying 15 to understand how you got here.
16 MR. VAN WERT: So the -- you'll hear about 17 it more later. The Hermes application actually had 18 even more information, and the staff's review of that 19 is going to be included there.
20 CHAIR PETTI: Ah.
21 MR. VAN WERT: So we were trying to figure 22 out where to put it. We could either have asked for 23 additional information to be put into the topical 24 report and address it here or just leave it there and 25 put the staff's review and approval within that 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
76 1 for the PSAR application.
2 CHAIR PETTI: Okay.
3 MR. VAN WERT: So you will hear about it 4 later.
5 CHAIR PETTI: Okay. I see Jeff Schmidt 6 has his hand up.
7 MR. VAN WERT: Okay.
8 MR. SCHMIDT: Yes, Dr. Petti, I was just 9 going to help Chris out here.
10 So I wrote the PSAR section for Hermes for 11 the fuel and I thought it was just better to use the 12 specific data for Hermes to address the lack of 13 transient testing. So that's why it rolled from this 14 topical report into the PSAR.
15 CHAIR PETTI: Okay. Thanks.
16 MEMBER REMPE: So this is Joy and I had a 17 question or two.
18 MR. VAN WERT: Yes?
19 MEMBER REMPE: It's tracking things. For 20 example, my question earlier about well, gee, KP-BISON 21 hasn't been validated and there's data required for 22 it. And I assume the staff is tracking all this very 23 carefully, because again their presumption that it's 24 okay to do this for the now-power application is based 25 upon KP-BISON calculations.
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 Likewise, I'm curious about if your 2 approval has considered things like buoyancy tests 3 only go to 900 C, but the power reactor is supposed to 4 have a normal -- it's like 1,100 C for operating. And 5 so are you tracking and saying okay, they can use it 6 for Hermes, but not the other reactor until they do 7 higher temperature testing? Is there some place where 8 the staff has all this documented carefully?
9 MR. VAN WERT: So I'll try to address it 10 all; please let me know which parts I miss and I'll go 11 back to it.
12 So yes, the initial -- and Jeff was the 13 lead reviewer for the KP-BISON topical report, and he 14 can jump in as well I'm sure. But the initial topical 15 report in this review is associated on its -- on the 16 data supplied by the AGR-2 Program. And within those 17 bounds -- yes, Hermes is going to operate within 18 those.
19 When you're talking about updating KP-20 BISON in the future as we're getting this data, that's 21 for when we're looking at operations outside of the 22 AGR-2 Program. So I wanted to make sure that that was 23 clear.
24 Joy, was there --
25 MEMBER REMPE: So let me stop you real 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 quick here.
2 MR. VAN WERT: Yes, yes.
3 MEMBER REMPE: So you're telling me you 4 have confidence even though KP-BISON hasn't been fully 5 validated, it has been validated using the data from 6 AGR testing -- that you feel comfortable that all of 7 their assumptions are correct about the operating 8 conditions for Hermes and there's nothing that needs 9 more data?
10 MR. VAN WERT: So I am going to kick that 11 one over to Jeff --
12 MR. SCHMIDT: Yes.
13 MR. VAN WERT: -- since he's the author 14 for KP-BISON's --
15 MR. SCHMIDT: Dr. Rempe, so for -- some of 16 this stuff I think we can talk about in the closed 17 session. The short answer is yes for Hermes. We 18 looked at the operating conditions and the test ranges 19 and it's fine for Hermes. I don't know if I looked 20 personally at the commercial design. I might have to 21 go back and take a look at that, but for the Hermes it 22 is.
23 MEMBER REMPE: Okay. Because I mean they 24 don't have material compatibility testing done yet for 25 Flibe and the fuel, and I would have thought 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
79 1 would be something that would be important for KP-2 BISON. And I thought there was a lot of other testing 3 where they acknowledged they used some data that had 4 been collected in the literature, but they wanted 5 additional data. And I would have to go back and look 6 at what all needed to be obtained, but I thought 7 basically they were missing some just fundamental 8 properties of materials.
9 MR. SCHMIDT: Yes.
10 MEMBER REMPE: And I'm a little surprised 11 that they are --
12 MR. SCHMIDT: So let me clarify my 13 statement, I guess. The ranges of data, ranges of 14 like temperatures I was responding to, there has been 15 on V&V of the BISON code.
16 MEMBER REMPE: Okay. So that will have to 17 be --
18 MR. SCHMIDT: That's all I really need to 19 say about that.
20 MEMBER REMPE: That will have to be done 21 before one can have confidence that they don't need to 22 have additional irradiation testing for Hermes, right?
23 MR. SCHMIDT: Yes, that is correct. For 24 an operating license for Hermes our expectation is 25 that those will be -- the codes will be V&V'ed. 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
80 1 the codes that --
2 MEMBER REMPE: They might --
3 MR. SCHMIDT: -- are necessary for Hermes.
4 MEMBER REMPE: They may have a surprise 5 then. They'll build the reactor, get a construction 6 permit. And then they may have a surprise because the 7 NRC could say oh, well, you know, it's not validated 8 and you need to get some more data here. And that 9 could happen. Just so everybody understands that 10 because it wasn't clear to me from the SE and from the 11 initial responses today.
12 And then when you go to the up-rated 13 electric power KP-FHR, somebody needs to do a careful 14 look at this SC, because again they only did testing 15 for buoyancy up to 900 C. And I was curious why they 16 didn't go on up to 1,100 C, but I thought well, okay, 17 if that's all you need to do for Hermes, okay, but the 18 staff SE should maybe make a note somehow or other 19 that they did not -- that that SE is only valid for 20 Hermes because higher temperatures or other types --
21 I didn't go through and look at all of the conditions, 22 but they didn't do -- they're not planning or 23 proposing to do testing for the full electric power 24 KP-FHR.
25 MR. VAN WERT: To be clear, what 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 temperature are you referring to? If you're talking 2 about --
3 (Simultaneous speaking.)
4 MEMBER REMPE: -- testing. If I look at 5 the anticipated electric power conditions, it's less 6 than 1,100 C. And then if I go to the laboratory 7 testing on slide 29, test temperatures up to 900 C and 8 pressure up to 500 KP for buoyancy testing. So either 9 they need to bump up their test temperature a little 10 bit when they do it the first time or it's not going 11 to be valid for the electric power.
12 MR. VAN WERT: So I don't want to say the 13 specific number, because it's listed as proprietary, 14 but --
15 MEMBER REMPE: I'm looking at their open 16 slides, by the way. I'm not looking at anything --
17 MR. VAN WERT: Oh, okay. Okay. Sorry.
18 I was looking at --
19 (Simultaneous speaking.)
20 MR. VAN WERT: Okay. So I was looking at 21 table 3-17 from the topical report. And if you're 22 talking about the pebble surface temperature, I don't 23 think we're looking at the same number then.
24 MEMBER REMPE: Okay. So I'm looking at 25 anticipated conditions, which again it is the peak 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 silicon carbide. I don't have a surface temperature.
2 So you're saying the surface temperature will be 3 covered by the 900 C? Okay. That helps me then.
4 Have you looked carefully --
5 MR. VAN WERT: And once we get --
6 MEMBER REMPE: -- at all of the --
7 MR. VAN WERT: Once we get to -- yes, 8 we'll tell you numbers in closed.
9 MEMBER REMPE: Okay.
10 MR. VAN WERT: And I think I have a backup 11 slide with that table if we would like to see it, 12 but --
13 MEMBER REMPE: But for the open session 14 you've carefully looked at their test conditions and 15 it covers not only Hermes but also the electric power 16 design?
17 MR. VAN WERT: Well, you mean specific to 18 the buoyancy?
19 MEMBER REMPE: Well, all of the testing.
20 There's a lot of other testing that they --
21 MR. VAN WERT: Okay.
22 MEMBER REMPE: -- have too.
23 MR. VAN WERT: So yes. No, the answer to 24 that would be the equilibrium core conditions go above 25 and beyond the AGR-2 Program. And so some 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
83 1 irradiation tests are not bounded by the available --
2 (Simultaneous speaking.)
3 MEMBER REMPE: Right.
4 MR. VAN WERT: And that's why that was 5 addressed -- I think it's in Section 3.7.
6 MEMBER REMPE: Right. Other than the 7 irradiation tests --
8 MR. VAN WERT: Correct.
9 MEMBER REMPE: -- the laboratory tests is 10 where I have --
11 MR. VAN WERT: Yes, the laboratory tests 12 -- yes.
13 MEMBER REMPE: And you guys are tracking 14 what is and isn't covered for each design was the 15 underlying question here.
16 MR. VAN WERT: Correct. Correct.
17 MEMBER REMPE: Okay. Thank you.
18 MR. VAN WERT: Yes, thanks.
19 CHAIR PETTI: Jeff has his hand up, Chris.
20 MR. VAN WERT: Okay. Hey, go ahead, Jeff.
21 MR. SCHMIDT: Yes, I was just going to say 22 there's other material limits, Dr. Rempe, that would 23 stop you from going above 900 C. And we can probably 24 discuss those more in the closed session.
25 MEMBER REMPE: Thank you.
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 MR. TOMKINS: Could I just add one point 2 following that discussion? And that is that the --
3 you were talking about validation of KP-BISON. So 4 Kairos is working on that right now. So I'm not 5 saying it's done yet, but we're -- that's something 6 we're actively working on.
7 MEMBER REMPE: Good. But I hope you have 8 data to finish it, because that was my impression when 9 I was looking at the SE is that yes, okay, it sounds 10 like a good idea, but until you have data -- and, you 11 know? So anyway.
12 MR. TOMKINS: Yes. Okay.
13 MR. VAN WERT: So were there any more 14 questions or --
15 CHAIR PETTI: Chris, I want to throw the 16 question I threw to Kairos to you guys: Why didn't 17 you require an irradiation given the Chinese even 18 proof irradiation test. I mean I just can't 19 understand. Is it because it's a test reactor that 20 somehow it has a lighter touch?
21 MR. VAN WERT: We kind of -- we had to 22 look at it holistically. So we were looking at the 23 literature data that was presented. We were looking 24 at the gas environment irradiation tests that they do 25 plan to do. And then also recognizing that they 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
85 1 a surveillance plan. So at the end of -- well, at the 2 end of both, Hermes as well as the power reactor, but 3 in this case of interest it's the end of Hermes they 4 will be doing all sorts of examinations including the 5 non-destructive and destructive PIE. And so that data 6 will become available.
7 And then also their ability to look at the 8 cover gas products as they accumulate allows them to 9 kind of keep on top of it. So if you look at it 10 holistically in its entirety, we felt that the 11 reasonable assurance threshold was crossed and we felt 12 it was a good foundation.
13 I am not opposed if they so desire to do 14 additional tests, but we had to make that safety 15 determination and that was where we came from.
16 CHAIR PETTI: So the key issue is that 17 yes, the gas will tell you if you failed all the 18 TRISO, but if you feel the silicon carbide, it's a lot 19 harder to do that for monitoring. That's why I was 20 intrigued initially when I read about the salt. I'm 21 just not sure if it will have the sensitivity. I'd be 22 interested to see what a computer model would say 23 there.
24 But in the old days when the South African 25 pebble bed came in, the folks sitting in your seats 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 were basically telling them they had to take pebbles 2 out periodically and look at them and examine them 3 sort of as a fuel surveillance -- as part of the fuel 4 surveillance program.
5 MR. VAN WERT: Yes, and at the operational 6 plans for Hermes, I don't think it gets -- it doesn't 7 stress it enough until you're towards the end of its 8 life. So I think the surveillance plan, the test data 9 that you collect at the end of it is going to be more 10 telling and more -- of the full power operation later.
11 If we took it out at 25 percent power, unless there 12 was a -- like you were alluding to earlier, a 13 manufacturing defect that would be gross over the vast 14 majority of pebbles and particles, I think that's the 15 only case where you would potentially see something.
16 And we couldn't find a way of thinking of that 17 happening.
18 Yes, we can discuss more I suppose in the 19 closed session all together, but that -- I just wanted 20 to give you at least that overview of the approach we 21 took as far as looking at all the different 22 components. And adding it together in aggregate we 23 thought was a strong safety case.
24 CHAIR PETTI: I see Jeff's hand's up.
25 Jeff?
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 MR. SCHMIDT: Yes, I just wanted to chime 2 in, too. I think you asked a good question there.
3 For me it was the destructive testing for the initial 4 non-power test reactor personally as a reviewer. That 5 was important to me to add to be able to use the test 6 reactor to get data in a real-life FHR, right? The 7 data that you might be referring to would still be say 8 in a gas environment.
9 CHAIR PETTI: Yes.
10 MR. SCHMIDT: This getting data from a 11 prototypical reactor is probably the most informative 12 you could do, or you could get. So we, at least I 13 thought that was the key in proceeding forward.
14 CHAIR PETTI: Yes. No, I would not 15 recommend that they have to test it in salt. That's 16 not an easy thing to do in a test reactor. Very 17 difficult to prevent the salt from freezing all the 18 time. If you have an unexpected scram in your test 19 reactor, which happens, it's much more challenging to 20 do a salt -- flowing salt experiment in the test 21 reactor.
22 MR. SCHMIDT: So it does kind of -- I 23 think from the staff's perspective it does kind of 24 leverage the test reactor aspect.
25 CHAIR PETTI: Yes, it just doesn't come 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 through enough I guess in either the topical report or 2 the SE that -- it comes across as sort of after the 3 fact. It doesn't come through enough to me at least.
4 Okay.
5 MR. SCHMIDT: Yes, there was significant 6 -- all I can tell you is there was very significant 7 dialog between us and Kairos regarding that item.
8 CHAIR PETTI: Yes. Okay.
9 MEMBER REMPE: In that dialog did you ask 10 them how much fluence they intend to accumulate with 11 Hermes? I mean, I know they're going to shut it down 12 like in four years, right? And when we asked, they 13 didn't really have any sort of specification for 14 capacity factor. So do you need to have any sort of 15 fluence -- total operating history you want to see?
16 MR. SCHMIDT: Yes, I mean, it's bounded by 17 the fluence by the AGR-2 Program from a particle 18 standpoint, if that's what you're referring to, the --
19 (Simultaneous speaking.)
20 MEMBER REMPE: I'm talking about Hermes.
21 How much -- have you --
22 (Simultaneous speaking.)
23 MR. SCHMIDT: You mean like from a vessel 24 fluence?
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
89 1 MEMBER REMPE: -- up to power or do you 2 want it at full power after so many days?
3 MR. SCHMIDT: No, I mean we're not 4 specifying. I think the assumption in Hermes is that 5 it's 100 percent capacity factor, which is probably 6 unrealistic --
7 (Simultaneous speaking.)
8 MEMBER REMPE: Well, I don't think they've 9 ever said that, because we asked them. Maybe they can 10 speak up, but I know we asked them that when we had 11 the overview introduction. I mean, it's only going to 12 run for four years. And I asked about the capacity 13 factor, and they said they hadn't come up with that.
14 Are you guys trying to do 100 percent 15 capacity factor?
16 PARTICIPANT: That's in closed section.
17 PARTICIPANT: We moved that to the closed 18 session also.
19 MEMBER REMPE: Sure.
20 CHAIR PETTI: Sure. So let me ask a 21 different question, Chris. They've committed to doing 22 an irradiation test in the topical for the power 23 reactor, but if things go swimmingly well in Hermes 24 and they're going -- like if they could come up with 25 a way to do it in Hermes, would that be allowed? I 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 mean, they'd obviously have to file more paperwork, 2 but they'd go beyond AGR-2, but they'd use Hermes 3 instead of a test reactor. Would that be something 4 that is at least not off the table?
5 MR. VAN WERT: So I mean if they could run 6 Hermes such that they could get that data, that would 7 be in my opinion fine. I would support having that 8 data ahead of time. But our understanding of the 9 power levels, the fluence, the burnups, et cetera, 10 that they can achieve within Hermes -- and keep in 11 mind it's also with a time frame. They could achieve 12 higher burnup by operating it longer of course, but at 13 some point at the power levels that Hermes will 14 operate at they're going to run out of time before 15 they want to build the full-power version of KP-FHR.
16 So we're not opposed to it. I just don't 17 think that Hermes will get them to those levels beyond 18 AGR-2 within the time frame that they'll need. So 19 that's why I think they're ending up in this space 20 where they're using a non-power -- sorry, a non-Hermes 21 test facility --
22 CHAIR PETTI: Sure. Yes.
23 MR. VAN WERT: -- to get those levels.
24 CHAIR PETTI: Okay. Thanks.
25 Other members, 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
91 1 Okay. Well, let's open the line for 2 public comment before we go into our closed session 3 then.
4 Any members of the public, un-mute 5 yourself, state your name and your comment for the 6 record.
7 Hearing none, I guess we're concluding the 8 open session and we will get onto the closed session 9 for other comments from members.
10 And, Jim, you'll scan the list to make 11 sure everybody on your side is supposed to be there?
12 And I suppose Chris and Jeff will do the same on the 13 NRC side.
14 MR. TOMKINS: Yes, could I ask for anybody 15 from the Kairos team, if you're going to call in by 16 phone, let -- send me an email saying that. Does 17 anybody plan to call in by phone or is everybody going 18 to use the Teams link?
19 Okay. I didn't hear anybody saying 20 they're going to call in by phone. So I think we 21 should be okay because we should -- they'll have the 22 link.
23 MEMBER BALLINGER: Dave, this is Ron. We 24 have a separate invitation. Are we just going to stay 25 here?
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 CHAIR PETTI: No, no. We're going to go 2 over to the separate -- we got to switch over to the 3 separate invitation.
4 MEMBER BALLINGER: I got it. Okay.
5 MR. TOMKINS: So and again, everybody from 6 Kairos, open up the closed file.
7 And so, Dave, what, are we going to go 8 there right now? Do you want to --
9 CHAIR PETTI: Yes.
10 MR. TOMKINS: -- take a short break?
11 MEMBER BROWN: Hold on. Dave, Dave, Dave?
12 CHAIR PETTI: Yes, Charlie?
13 MEMBER BROWN: This is Charlie. Yes, did 14 we get the closed session slides? I had looked for 15 those and couldn't find them.
16 PARTICIPANT: There aren't any.
17 MR. WANG: I will send to you. It should 18 be on your calendar. You're Charlie, right?
19 MEMBER BROWN: I got two sets of slides.
20 They were both open.
21 CHAIR PETTI: Yes, there's no closed 22 slides, Charlie. It's just for some Q & A.
23 MEMBER BROWN: Okay. That's all I wanted 24 to know. Thank you.
25 CHAIR PETTI: Okay. So we're going 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
93 1 terminate this one and see everybody in the closed 2 session.
3 MR. WANG: And I will admit Jim. And 4 then, Jim, then you help me to look at your need to 5 know people. Okay. Thank you.
6 MR. TOMKINS: Will do. Thank you.
7 CHAIR PETTI: Thank you.
8 (Whereupon, the above-entitled matter went 9 off the record at 4:04 p.m.)
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
KP-FHR Fuel Qualification Methodology Topical Report K A IRO S P OW E R AC RS K A IRO S P OW E R S U B CO M M IT T E E M E E T IN G O C TO B E R 1 7 , 2 0 2 2 O PE N S ES S IO N Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Introduction
- Topical Report Applicability This report presents a methodology for qualifying fuel for use in KP-FHRs Qualification subject to the conditions in topical report Demonstration of qualification will be documented in safety analysis report documents as part of licensing applications under Part 50 or Part 52 This report is applicable to a test or power KP-FHR provided that the report conditions are met 2
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
2 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Qualification Qualified fuel means fuel for which reasonable assurance exists that the fuel, fabricated in accordance with its specification, will perform as described in the safety analysis.
3 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
3 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
KP-FHR and Fuel Design Copyright © 2022 Kairos Power LLC. All Rights Reserved.
4 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
KP-FHR Overview Parameter Description / Value Reactor Name Hermes KP-X Commercial Electric Reactor Type Non-Power Test Reactor Power Reactor Reactor Vessel Size 3 m dia., 4.4 m ht. 4 m dia., 6 m ht.
Coolant / Reflector Flibe / Graphite Flibe / Graphite Reactor Thermal /
35 MWth / N/A 320 MWth / 140 MWe Electric Power Reactor Operating
<0.2 MPa <0.2 MPa Pressure Reactor Inlet /
550°C / 620°C 550°C / 650°C Outlet Temperature Copyright © 2022 Kairos Power LLC. All Rights Reserved.
5 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Annular Fuel Pebble and TRISO Particle Design 40mm diameter
<1mm diameter 6
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
6 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Particle Design Fuel System Component Purpose UCO Kernel
- The kernel contains the fissile material.
UO2 + UC + UC2
- The addition of a limited amount of uranium carbide suppresses CO production mitigating kernel migration, particle over-pressure, and corrosion of the SiC layer.
- Oxygen remains sufficient to oxidize fission products that would otherwise diffuse through the IPyC and attack SiC in the higher mobility carbide form.
Porous Carbon Buffer Layer
- The porous carbon buffer layer provides void volume to accommodate fission product gases limiting pressure as burnup increases.
- This layer mechanically de-couples the kernel from the outer coating layers and accommodates fuel kernel swelling.
- This layer protects the IPyC from damage by fission product recoil.
IPyC Layer
- This coating layer is considered to be the secondary structural and fission product gas barrier after the SiC layer.
- This layer introduces a compressive stress on the SiC layer that reduces SiC deformation and the risk of SiC layer failure during irradiation.
- This layer serves to protect the SiC from fission product attack.
- The IPyC layer protects the kernel from chlorine attack during SiC7 deposition in the manufacturing process.
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
7 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Particle Design (continued)
Fuel System Component Purpose SiC Layer
- The SiC layer is the primary structural layer and fission product barrier.
- This layer is a diffusion barrier to mobile metallic and gaseous fission products.
OPyC Layer
- This coating layer is considered to be a secondary structural and fission product gas barrier after the SiC layer.
- This layer introduces a compressive stress on the SiC layer during irradiation that reduces SiC deformation and the risk of SiC layer failure.
- The OPyC layer protects the SiC layer during manufacture separating the SiC layer from the carbon over-coat.
Pebble - Particle Carbon Over-Coat
- The TRISO particle overcoat with carbon matrix material prevents particle-to-particle contact during manufacture.
- The overcoat also facilitates obtaining the nominal packing fraction in the pebble fuel region during manufacture.
8 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
8 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Pebble Design (continued)
Fuel System Component Purpose Low-density Carbon Core
- Reduces the pebble density ensuring pebble has net positive buoyancy in the Flibe coolant.
Fuel Region
- Embedded with TRISO fuel particles at the nominal packing fraction.
- This region locates fuel near the coolant decreasing the thermal resistance allowing particle powers to be high while keeping fuel temperatures within limits.
Fuel-Free Carbon Outer Shell
- The fuel-free carbon outer shell protects the fuel region from mechanical damage and separates the fuel particles from the coolant.
9 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
9 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Qualification Methodology Copyright © 2022 Kairos Power LLC. All Rights Reserved.
10 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Qualification Methodology
- U.S. and International Experience Foundation of TRISO fuel particle technology NRC SER on EPRI TRISO topical report
- Kairos Fuel Pebble and Particle PIRT The fuel element PIRT is used to identify high priority phenomena for investigation in the fuel qualification program
- Fuel Specification, Manufacturing, and Quality Control through Inspection Fuel specification equivalent to the AGR program with quality controlled through inspection
- Fuel Qualification Envelope Operation is within the bounds of qualification envelope, otherwise an irradiation test is needed to expand the operational envelope 11 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
11 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Qualification Methodology (continued)
- Fuel Pebble Laboratory Testing Demonstrate reasonable assurance that pebble will meet functional requirements
- Fuel Irradiation Testing An irradiation test of a statistically significant number of TRISO fuel particles at conditions that extends the bounds of AGR irradiation test data to support a wider operational envelope
- Fuel Performance Model Physics based models in KP-BISON are a quantifiable representation of fuel knowledge used for core design and source term analysis
- Fuel Surveillance Program Ongoing confirmation of fuel performance 12 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
12 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
U.S. and International Experience Copyright © 2022 Kairos Power LLC. All Rights Reserved.
13 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Summary of U.S. and International Experience
- The use of UO2 TRISO-coated particle fuel first occurred in the UK in the early 1960s with irradiation the Dragon Reactor.
- The German pebble-bed reactor designs (mid-1970s thru Peak Average Peak Peak National Fluence 1988) led to extensive testing and real time irradiation in Particle Power Temperature Burnup (x1025n/m 2, Program the AVR of full commercial scale production fuel (mW) (°C) (%FIMA)
E>0.1MeV)
- China and Japan have successfully developed TRISO fuel German 100 - 250 800 - 1320 6.7 - 15.6 0.2 - 8.5 production and irradiated fuel in prototype and commercial reactors of the prismatic and pebble bed type Chinese 150 - 250 1017 - 1067 9 - 11 3.8 - 4.9 Japanese 550 1156 6.7 2.8
- In the US, General Atomics operated prototype and demonstration gas reactors using uranium/thorium carbide U.S. Legacy 100 - 400 915 - 1350 12 - 80 2.1 - 11.5 based coated fuel particles in prismatic cores U.S. AGR 55 - 140 800 - 1500 13.2 - 19.6 3.5 - 8.1
- The AGR program was built on this extensive experience to qualify a UCO TRISO coated fuel particle, Kairos Power leverages this DOE program 14 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
14 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
DOE AGR and German Irradiation Test Data Time Peak Particle Ave. Particle Peak Burnup Time-Ave. Peak Peak Fluence Test (EFPD) Power (mW) Power (mW) Compact (%FIMA) Temp. Compact Compact (x1021
(°C) n/cm 2, E > 0.1 MeV)
AGR-1 620 104 56 19.6 1197 4.7 AGR-2 559 155 73 13.2 1360 3.8 AGR-3/4 369 98 65 15.3 1418 5.8 AGR-5/6 361 247 107 15.3 1210 6.0 AGR-7 361 238 148 15.0 1405 6.1 Number of Number of SiC Failures TRISO Failures Test Compacts Particles Number of 95% Number of 95%
Failures Confidence Failures Confidence US DOE AGR-1 72 298,000 4 3.1x10-5 0 1.1x10-5 AGR-2 36 114,336 4 8.1x10 -5 4 8.1x10-5 Aggregate 108 412,336 8 3.6x10-5 4 2.3x10-5 German MTR Irradiation Tests of LEU UO2 TRISO Fuel Particles in 60mm Diameter Fuel Pebbles Pebbles --- 277,000 --- --- 0 1.1x10-5 The AGR irradiation tests have demonstrated performance equivalent to the German experience 15 which has historically been considered the standard for TRISO fuel performance.
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
15 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
DOE AGR and German Furnace Safety Test Data Test Number of Number of SiC Failures TRISO Failures Temperature Compacts Particles Number of 95% Number of 95%
(°C) Failures Confidence Failures Confidence AGR-1 1600 8 33,100 3 2.4x10-4 0 9.1x10-5 1700 3 12,400 7 1.1x10 -3 0 2.5x10-4 1800 4 16,500 23 2.0x10-3 2 3.9x10-4 AGR-2 1600 4 12,704 0 2.4x10-4 0 2.4x10-4 1800 3 9,528 1 5.0x10-4 1 5.0x10-4 AGR-1 and AGR-2 1600 12 45,804 3 1.7x10-4 0 6.6x10-5 1800 7 26,028 24 1.3x10-3 3 3.0x10-4 German Tests of LEU UO2 TRISO Fuel Particles in 60mm Diameter Fuel Pebbles 1600 19 287,480 --- --- 5 3.7x10-5 AGR and German furnace safety testing data demonstrates the high reliability of TRISO fuel particles 16 up to 1600°C and above.
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
16 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Kairos Fuel Pebble and Particle PIRT Copyright © 2022 Kairos Power LLC. All Rights Reserved.
17 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Particle and Pebble PIRT
- Foundation 2004 TRISO PIRT - NUREG/CR-6844
- Fuel element PIRT identifies high priority phenomena to investigate in relation to the FOM fission product transport and release
- Kairos PIRT o 199 Phenomenon Identified o TRISO fuel particles only had Rank 2 (High importance, medium knowledge level) rankings o Pebble fuel elements had more diverse rankings due to the novel design, manufacturing, and performance of the annular pebble 18 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
18 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Particle and Pebble PIRT PIRT Findings are Addressed:
- Manufacturing Development Program Leverages German and AGR program experience
- Fuel Pebble Laboratory Testing Program Mechanical - Tribology, Compression, Impact, Molten Salt Infiltration Material Compatibility - Pebble in Flibe, Pebble in Air 19 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
19 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Specification, Manufacturing, and Quality Control through Inspection Copyright © 2022 Kairos Power LLC. All Rights Reserved.
20 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Specification, Manufacturing, and Quality Control
- TRISO Particle Specification Based on AGR Specification Equivalent specification to AGR-2 and AGR-5/6/7 TRISO fuel particles
- Pebble Specification Similar to historic HTGR fuel pebbles with features for FHRs
- Manufacturing Kernels fabricated using sol-gel process to form microspheres Coated particles are fabricated in a fluidized bed through a continuous chemical vapor deposition (CVD) process Pebbles are formed from a mixture of matrix graphite powders, binder, and TRISO fuel particles and pressed to shape and heat treated
- Inspection Products are characterized to demonstrate compliance with specifications 21 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
21 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Specification, Manufacturing, and Quality Control Source Material or Fabricated Measured Characteristic in Inspection Program Component U3O8 U-235 enrichment, uranium content, impurities, boron equivalent Kernel Diameter, density, sphericity, stoichiometry, impurities TRISO fuel particle Layer thickness, density, PyC anisotropy, SiC aspect ratio, surface and free uranium content Natural and petroleum coke Density, grain size, surface area, impurities, boron equivalent graphite Binder material Viscosity, molecular weight, melting point, impurities Pebble fuel Density, diameter, thermo-physical properties, mechanical properties, thickness of fuel free outer shell, surface defects, fraction of defective SiC layers (burn leach), uranium loading, uranium contamination in carbon matrix, ash and lithium content, boron equivalent 22 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
22 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Qualification Envelope Copyright © 2022 Kairos Power LLC. All Rights Reserved.
23 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Operating Envelope
- Key Parameters Power Burnup Temperature Fast Fluence
- The KP-FHR operating conditions for steady state and transients must be within the fuel qualification envelope The basis of the qualification envelope are the AGR-2 irradiation conditions defined in the EPRI TRISO topical report 24 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
24 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Operating Envelope and Qualification Limits Anticipated Proposed Anticipated Non-Power Commercial Electric Parameter Qualification Test KP-FHR Conditions Power KP-FHR Envelope Conditions Normal Operation Peak SiC Layer Temperature (°C) 1360 < 900 < 1100 Burnup (%FIMA) 13.2 < 10 < 20 Peak Particle Power (mW) 155 < 155 < 350 25 2 Peak Fluence (x10 n/m ,
3.8 < 2.0 < 4.0 E>0.1MeV)
Postulated Events Peak SiC Layer Temperature (°C) 1600 < 1200 < 1200 Peak Kernel Temperature (°C) 2350 < 1500 < 1500 25 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
25 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Pebble Laboratory Testing Copyright © 2022 Kairos Power LLC. All Rights Reserved.
26 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Laboratory Test Program
- Fuel Pebble Laboratory Test Program will demonstrate that annular fuel pebbles meet functional requirements
- Mechanical Tests
- Tribology
- Buoyancy and Molten Salt Infiltration
- Material Compatibility Copyright © 2022 Kairos Power LLC. All Rights Reserved.
27 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Mechanical Tests and Tribology
- Demonstrate pebbles do not fracture from static and dynamic loads in the reactor and wear behavior is acceptable for a pebbles lifetime
- Compression test Compression test (crush test)
Pebble is loaded in compression until failure
- Impact test Pebble fracture under cyclic impacts
- Tribology Wear rate and coefficient of friction Copyright © 2022 Kairos Power LLC. All Rights Reserved.
28 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Buoyancy, Molten Salt Infiltration (MSI) Tests and Material Compatibility
- Flibe Infiltration and Buoyancy Demonstrate pebbles are buoyant Test temperature up to 900°C and pressure up to 500 kPa Measurement of weight change
- Flibe Compatibility Pebble carbon matrix interaction with Flibe
- Air Compatibility Oxidation rate behavior of pebble carbon matrix in Air Oxidation tests in the temperature range 450-700°C Measurement of mass loss with time to create an Arrhenius correlation Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC. 29
Laboratory Test Program Acceptance Criteria Laboratory Test Measured Parameter Acceptance Criteria Program Compression Crush strength The crush strength at room temperature is greater than the maximum calculated load in the core, PHSS, and during receipt and inspection.
Impact Pebble fracture The pebble will not fracture under cyclic impact in the core, PHSS, and during receipt and inspection.
Tribology Wear rate The wear determined by a conservative analysis of wear over the lifetime of a pebble does not result in damage to the TRISO particles.
30 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
30 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Laboratory Test Program Acceptance Criteria (continued)
Laboratory Program Test Measured Parameter Acceptance Criteria Buoyancy Density (mass and volume), Measurements of pebble density and Flibe density made coefficient of thermal expansion over the operating range ensure that the pebble remains buoyant.
Buoyancy Flibe infiltration Flibe infiltration measured over operating range as well as the range of all transients to ensure the pebble remains buoyant.
Material Compatibility Corrosion rate of the pebble carbon Flibe interaction with the pebble does not result in matrix in Flibe damage to the fuel region of the pebble.
Material Compatibility Corrosion rate of pebble carbon Air material compatibility tests analyzed over the lifetime matrix in air of a pebble does not result in damage to the fuel region of the pebble.
31 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
31 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Irradiation Testing Copyright © 2022 Kairos Power LLC. All Rights Reserved.
32 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Irradiation Testing
- Irradiation testing expands the fuel qualification envelope Testing is required for the commercial electric power reactor
- Tests would be performed in a non-KP-FHR test facility
- Online fission gas release data used to determine the TRISO fuel particle failure fraction
- Destructive PIE is used to confirm the TRISO fuel particle failure fraction
- Acceptance criteria TRISO fuel particle failure fraction with a 95% one-sided upper confidence bound 33 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
33 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Performance Model Copyright © 2022 Kairos Power LLC. All Rights Reserved.
34 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Performance
- KP-BISON used to analyze response of the fuel during normal operation and transients
- Fuel Pebble DEM modeling
- Fuel Pebble Finite Element Modeling 35 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
35 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Surveillance Program Copyright © 2022 Kairos Power LLC. All Rights Reserved.
36 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel Surveillance Program
- Fuel surveillance in Hermes confirms fuel performance
- Fission product monitoring Cover gas Flibe coolant
- PHSS pebble inspection system checks burnup and physical condition
- Post irradiation examination in Hermes (and initial KP-X)
TRISO particle failure fraction Pebble surface wear Molten salt infiltration Copyright © 2022 Kairos Power LLC. All Rights Reserved.
37 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Summary
- Over fifty years of operating experience and testing of TRISO fuel including extensive testing of TRISO fuel particles in AGR-1 and AGR-2, including for both steady state and transient conditions.
- Successful completion of a KP-FHR fuel element PIRT and implementation of associated actions to further the understanding of the annular fuel pebble and TRISO fuel particles.
- Manufacturing and inspection of the KP-FHR fuel to a specification that ensures the fuel is equivalent in performance to the fuel tested in AGR-2, and meets the conditions in the EPRI TRISO topical report SER (Reference 13).
- Operation within a set of defined fuel qualification limits which ensure that the fuel remains within its qualification envelope during both normal operation and licensing basis events.
38 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
38 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Summary (continued)
- Irradiation testing (if TRISO fuel particle will operate outside of the AGR-2 fuel performance envelope)
- Surveillance program confirms that the pebble form does not have an adverse impact on the fuel particles.
- The ability to examine fuel pebbles as they exit and re-enter the core over their expected lifetime, including the ability to remove them if necessary for disposal or PIE.
39 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
39 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Limitations
- The design of the annular pebble, TRISO particle-based fuel and the KP-FHR design overview are as described in Section 1.1.2, including the presence of a Flibe primary coolant.
- Operating and transient conditions for the KP-FHR are demonstrated in safety analysis reports submitted with license applications under 10 CFR 50 and 10 CFR 52 to remain within the fuel qualification envelope values specified in Table 3-11, which is based on the AGR program.
- If the fuel qualification envelope is to be extended beyond the AGR-2 based limits, an irradiation test program will be conducted.
- Demonstration that the conditions and limitations of the EPRI TRISO Topical Report Safety Evaluation Report are met for the KP-FHR fuel design.
- Future license applications for commercial electric power KP-FHRs will include justification (testing or analysis based on an approved methodology) of the applicability of this methodology during rapid reactor transient events for irradiated fuel.
- Future license applications for commercial electric power KP-FHRs will include additional justification (testing or analysis based on an approved methodology) that Flibe does not adversely impact irradiated fuel pebble buoyancy.
- This methodology applies only to KP-FHRs with a safety-related positive flux rate trip.
- SER limitation to justify applicability of this methodology to a test reactor for rapid transients.
40 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
40 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
End of Presentation Questions?
41 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
41 No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
NRC Evaluation of KP-TR-011-P, Fuel Qualification Methodology for the Kairos Power Fluoride Salt-Cooled High Temperature Reactor (KP-FHR), Rev. 2 Chris Van Wert US Nuclear Regulatory Commission October 17, 2022
Introduction
- Kairos Power, LLC requested staff review and approval of KP-TR-011-P, Rev. 2, Fuel Qualification Methodology for the Kairos Power Fluoride Salt-Cooled High Temperature Reactor (KP-FHR)
- Provides a methodology by which the Kairos fuel pebble design will be qualified for use in either a KP-FHR non-power or KP-FHR power reactor
- The staffs review focused on the overall qualification framework including:
- Use of existing data
- Unirradiated testing
- Irradiation testing
- Surveillance 2
Regulatory Basis Title 10 of the Code of Federal Regulations (10 CFR) Sections 50.34(a),
50.34(b), 50.43(e), and corresponding regulations for design certification applications, combined license applications and standard design approvals 10 CFR 100.11 Determination of exclusion area, low population zone and population center distance Kairos PDC 10 - Reactor design which has been approved by the staff (KP-TR-003-NP-A)
KP-FHR PDC 16, Containment Design which has been approved by the staff (KP-TR-003-NP-A) 3
Applicability of Existing Data
- KP-TR-011, Rev. 2, builds upon the approved topical report EPRI-AR-(NP)-1
- Kairos TRISO particle specifications comparable with the Advanced Gas Reactor campaign 2 (AGR-2) particle
- Non-power KP-FHR reactor operating conditions are bounded by AGR-2 test conditions
- Power reactor operating conditions exceed some AGR-2 test conditions
- Available carbon matrix property data are used to inform Kairos testing plans to support fuel qualification.
The staff reviewed the existing data use as outlined in the topical report and finds it acceptable for the stated uses.
4
Laboratory Pebble Testing KP-TR-011-P discusses planned laboratory tests to obtain Kairos fuel pebble data to support fuel qualification:
- Mechanical
- Tribology
- Buoyancy and Salt Infiltration
- Material Compatibility The staff reviewed the planned tests and found them acceptable for use in determining Kairos fuel pebble characteristics to support fuel qualification.
5
Irradiation Testing Section 3.7 of the topical report details irradiation testing which will be performed to support operation outside of the AGR-2 operational envelope, if desired
- Fuel pebble irradiation in a gas environment
- Purge gas monitoring for fission gas
- Post Irradiation Examinations The staff reviewed the irradiation testing plans from Section 3.7 of the topical report and finds them acceptable for determining irradiated failed particle fraction and gross pebble behavior which could potentially impact particle failures.
6
Fuel Performance Modeling Section 3.8 of the topical report addresses fuel particle performance modeling
- The staffs approval of this topical report is related to the methodology by which the Kairos fuel pebble can be qualified
- The data collected by adherence can be used in updating or building a fuel performance model
- The staffs approval of the fuel qualification topical report does not approve a priori any modifications to the Kairos fuel performance code KP-BISON 7
Fuel Surveillance Section 3.9 of the topical report addresses fuel surveillance plans for the initial test and power KP-FHR cores which are used to both monitor fuel performance and to collect data for fuel performance models
- Cover gas monitoring
- Destructive examinations The staff finds that the fuel surveillance methods are robust and can detect failed particles, pebbles at the end of life, and damaged pebbles which could lead to particle failure.
8
Staff Limitations The staffs approval of KP-TR-011-P includes the following staff limitation in addition to the limitations provided by Kairos in Section 4.2 of the topical report:
Future license applications for non-power KP-FHRs will include justification of the applicability of this methodology during rapid reactor transient events.
9
Conclusions The staff reviewed the topical report KP-TR-011-P, Rev. 2 and concludes that the fuel qualification methodology contained within is acceptable for supporting fuel qualification of Kairos fuel pebbles in either non-power or power reactor versions of the KP-FHR.
10
Questions?
11