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
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 1
1 2
3 DISCLAIMER 4
5 6
UNITED STATES NUCLEAR REGULATORY COMMISSIONS 7
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 8
9 10 The contents of this transcript of the 11 proceeding of the United States Nuclear Regulatory 12 Commission Advisory Committee on Reactor Safeguards, 13 as reported herein, is a record of the discussions 14 recorded at the meeting.
15 16 This transcript has not been reviewed, 17 corrected, and edited, and it may contain 18 inaccuracies.
19 20 21 22 23
1 UNITED STATES OF AMERICA 1
NUCLEAR REGULATORY COMMISSION 2
+ + + + +
3 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 4
(ACRS) 5
+ + + + +
6 KAIROS POWER LICENSING SUBCOMMITTEE 7
+ + + + +
8 OPEN MEETING 9
+ + + + +
10 MONDAY 11 OCTOBER 17, 2022 12
+ + + + +
13 The Subcommittee met via Video 14 Teleconference, at 2:00 p.m. EDT, David Petti, 15 Chairman, presiding.
16 COMMITTEE MEMBERS:
17 DAVID PETTI, Chair 18 RONALD G. BALLINGER, Member 19 CHARLES H. BROWN, JR., Member 20 VESNA DIMITRIJEVIC, Member 21 GREGORY HALNON, Member 22 JOSE MARCH-LEUBA, Member 23 JOY L. REMPE, Member 24 MATTHEW SUNSERI, Member 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
2 ACRS CONSULTANTS:
1 DENNIS BLEY 2
4 DESIGNATED FEDERAL OFFICIAL:
5 WEIDONG WANG 6
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 ALSO PRESENT:
1 BENJAMIN BEASLEY, NRR 2
MATT DENMAN, Kairos Power 3
TIMOTHY DRZEWIECKI, Kairos Power 4
DARRELL GARDNER, Kairos Power 5
RUSSELL GARDNER, Kairos Power 6
MICAH HACKETT, Kairos Power 7
RACHEL HAIGH, Kairos Power 8
BRANDON HAUGH, Kairos Power 9
MICHELLE HAYES, NRR 10 ISHAK JOHNSON, Kairos Power 11 RYAN LATTA, Kairos Power 12 GABRIEL MERIC, Kairos Power 13 SCOTT MOORE, ACRS 14 DREW PEEBLES, Kairos Power 15 NADER SATVAT, Kairos Power 16 NICOLE SCHLICHTING, Kairos Power 17 JEFF SCHMIDT, NRR 18 JIM TOMKINS, Kairos Power 19 CHRIS VAN WERT, NRR 20 GARETH WHATCOTT, Kairos Power 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
4 CONTENTS 1
ACRS Chairman Introductory Remarks 5
2 NRC Staff Introductory Remarks 7
3 Kairos Power Introductory Remarks........
9 4
KP-FHR Fuel Qualification Methodology
..... 12 5
KP-FHR Fuel Qualification Methodology 6
Topical Report Safety Evaluation
........ 67 7
Public Comments................. 91 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
5 P R O C E E D I N G S 1
2:00 p.m.
2 CHAIR PETTI: Good afternoon, everyone.
3 The meeting will now come to order 4
This is a meeting of the Kairos Power 5
Licensing Subcommittee of the Advisory Committee on 6
Reactor Safeguards.
7 I'm David Petti, Chairman of today's 8
Subcommittee meeting.
9 ACRS members in attendance are Charles 10 Brown, Greg Halnon, Jose March-Leuba, and Ron 11 Ballinger. Dennis Bley and Steve Schultz, our 12 Consultants, are also online.
13 Weidong Wang, of the ACRS staff, is the 14 Designated Federal Official.
15 And I forgot Joy Rempe is also online.
16 During today's meeting, the Subcommittee 17 will review the staff's Safety Evaluation on the 18 Topical Report entitled "Fuel Qualification 19 Methodology for the Kairos Power Fluoride Salt-Cooled 20 High Temperature Reactor," Revision 2.
21 The Subcommittee will have presentations 22 by and hold discussions with the NRC staff, Kairos 23 Power representatives, and other interested persons 24 regarding this matter.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
6 The product presentations by the Applicant 1
and the NRC staff may be closed in order to discuss 2
information that is proprietary to the Licensee and 3
its contractors, pursuant to 5 USC 552b(c)(4).
4 Attendance at the meeting that deals with such 5
information will be limited to the NRC staff and its 6
consultants, Kairos Power, and those individuals and 7
organizations who have entered into an appropriate 8
confidentiality agreement with them. Consequently, we 9
need to confirm that we have only eligible observers 10 and participants in the closed part of the meeting.
11 The rules for participation in all ACRS 12 meetings, including today's, were announced in The 13 Federal Register on June 13th, 2019. The ACRS section 14 of the U.S. NRC public website provides our Charter, 15 Bylaws, agendas, Letter Reports, and full transcripts 16 of all full and Subcommittee meetings, including 17 slides presented there. The meeting notice and agenda 18 for this meeting were posted there.
19 We have received no written statements or 20 requests to make an oral statement from the public.
21 The Subcommittee will gather information, 22 analyze relevant issues and facts, and formulate 23 proposed positions and actions, as appropriate, for 24 deliberation by the full Committee.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
7 The rules for participation in today's 1
meeting have been announced as part of the notice of 2
this meeting previously published in The Federal 3
Register.
4 A transcript of the meeting is being kept 5
and will be made available, as stated in The Federal 6
Register notice.
7 Due to the COVID pandemic, today's meeting 8
is being held over Microsoft Teams for ACRS, NRC 9
staff, and the Licensee attendees.
10 There's also a telephone bridge line 11 allowing participation of the public over the phone.
12 When addressing the Subcommittee, the 13 participants should first identify themselves and 14 speak with sufficient clarity and volume, so that they 15 may be readily heard. When not speaking, we request 16 that participants mute your computer microphone or 17 phone by pressing *6.
18 We'll now proceed with the meeting, and 19 I'd like to start by calling upon NRR management.
20 Michelle Hayes will now make an opening statement.
21 MS. HAYES: Thank you, Dr. Petti.
22 I'm Michelle Hayes, Chief of Technical 23 Branch 1 in the Division of Advanced Reactors and Non-24 Power Production and Utilization Facilities in the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
8 Office of Nuclear Reactor Regulation.
1 We're happy to be meeting with you today.
2 As you know, the Hermes Test Reactor Construction 3
Permit Review is underway. The Topical Report we're 4
discussing today, and two others that we're going to 5
bring to you early next year, are referenced in this 6
Hermes application. So, these will need to be 7
finished before we complete the Construction Permit 8
Review.
9 We met with you on the Kairos Fuel 10 Performance Topical Report a year ago. The Fuel 11 Performance Report described a methodology for 12 modeling TRISO failed fuel fraction and fission 13 product released from the TRISO particles. Today, we 14 are discussing the Fuel Qualification Topical Report.
15 Kairos relies on the previously-approved 16 EPRI Topical Report for qualification of the TRISO 17 fuel particles. The Kairos Fuel Qualification Report 18 gives details on the qualification of the pebble form 19 of the fuel which will be used in their fluoride salt-20 cooled reactors.
21 The Kairos Report provides a method for 22 qualification that considers mechanical and structural 23 performance, as well as chemical, thermal, and 24 irradiation effects.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
9 After Kairos gives an overview of the Fuel 1
Qualification Report, NRC staff will give you an 2
overview of our report, our review and our Safety 3
Evaluation.
4 We will be glad to hear your insights and 5
comments. Are there any questions before we get 6
started?
7 Then I will turn it back over to Dr. Petti 8
or Kairos.
9 CHAIR PETTI: I just noticed that Vesna 10 Dimitrijevic has joined. So the court reporter can 11 report her as present.
12 Jim, it's all yours.
13 MR. TOMKINS: Okay. Thank you, Dr. Petti.
14 My name is Jim Tomkins, and I'm Manager of 15 Fuel Licensing at Kairos Power.
16
- Today, we're going to present our 17 methodology for qualifying our fuel for the Kairos 18 Power Reactors. Ryan Latta, who is our Principal 19 Engineer for Fuel Qualification, will be doing the 20 bulk of the presentation today.
21 We have individuals at various Kairos 22 locations, and I'm going to start with KP Headquarters 23 in Alameda, California. I just introduced myself.
24 Go ahead, Ryan.
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10 MR. LATTA: Yes, my name is Ryan Latta.
1 I'm a Principal Engineer for Fuel Qualification, and 2
I'll be giving most of the main technical talk today.
3 MR. JOHNSON: I'm Ishak Johnson. I'm a 4
Safety Analysis Engineer.
5 MR. MERIC: Gabriel Meric, Engineering 6
Fueling Materials.
7 MR. SATVAT: Hello. This is Nader Satvat, 8
Senior Manager of Core Design.
9 MR. DRZEWIECKI: I'm Tim Drzewiecki. I'm 10 a Senior Engineer, Safety Analysis.
11 MR. TOMKINS: Okay. Thank you.
12 In Charlotte, North Carolina, could folks 13 introduce themselves?
14 MR. D. GARDNER: Darrel Gardner, Senior 15 Director of Licensing.
16 MR. PEEBLES: And we've got Drew Peebles.
17 I'm a Licensing Manager for Safety.
18 MS. SCHLICHTING: Nicole Schlichting, 19 Senior Licensing Engineer.
20 MS. HAIGH: Rachel Haigh, Licensing 21 Engineer.
22 MR. PEEBLES: And that's it in Charlotte, 23 Jim.
24 MR. TOMKINS: Okay. And how about KP 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
11 Southwest?
1 MR. DENMAN: This is Matthew Denman. I'm 2
the responsible Engineer for Mechanistic Source Term.
3 MR. TOMKINS: Okay. Did I miss anyone?
4 Is anybody calling in by phone? I think so.
5 MR. WHATCOTT: Jim, I'm online. This is 6
Gareth Whatcott, Lead Engineer for Fuel Handling and 7
Storage.
8 MR. TOMKINS: Okay.
9 MR. HAGAMAN: Jordan Hagaman, Director of 10 Reliability Engineering and Quality Assurance at 11 Kairos Power.
12 MR. R. GARDNER: And Russell Gardner, 13 Senior Engineer of Fuel Performance.
14 MR. TOMKINS: Anyone else? How about 15 Micah?
16 Well, somebody should send Micah a Slack, 17 by the way. But is there anyone else who's on the 18 line for Kairos?
19 Okay. Rachel, do you want to go ahead and 20 bring up the slides?
21 While she's doing that, I just wanted to 22 touch again on proprietary and non-proprietary 23 materials. The slides are non-proprietary, but it's 24 conceivable that in the course of answering a question 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
12 we might have to reveal some proprietary information.
1 So, if we do that, we will kind of capture the 2
question and cover that during the closed session.
3 And with that, I'll turn it over to Ryan.
4 Next slide.
5 Actually, I'm turning it over to myself.
6 Sorry about that.
7 So, the applicability of this Topical 8
Report, as I've said before, it presents the 9
methodology for qualifying fuel for use in KP-FHRs.
10 Qualification is subject to the conditions in the 11 Topical Report.
12 I want to make a point that this Topical 13 Report is a methodology for qualification. It is not 14 the qualification. That's going to have to be 15 demonstrated over the coming months and year or so.
16 And that qualification will be documented in Safety 17 Analysis Report documents as part of licensing 18 applications.
19 The Topical is applicable to a test or 20 power KP-FHR, provided that the conditions are met, 21 but some of the conditions apply to one or the other.
22 Next slide.
23 So, qualification. So, qualified fuel 24 means fuel for which there's a reasonable assurance 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
13 that the fuel, if it's fabricated in accordance with 1
its specification, will perform consistently with the 2
Safety Analysis. So, that's kind of a working-level 3
definition we've been using.
4 And now, I'll turn it over to Ryan, who is 5
going to talk a little bit about our design and our 6
fuel, and then, he'll go through the qualification 7
methodology.
8 CHAIR PETTI: So, Jim, this is Dave. Just 9
a question.
10 So, this report outlines all of the tests, 11 analytical approaches, whatever you want to call it, 12 that when taken together, collectively constitute fuel 13 qualification from a scope perspective?
14 MR. TOMKINS: Yes.
15 CHAIR PETTI: Okay. Thank you.
16 MR. LATTA: Okay. Can you advance one 17 slide?
18 MR. TOMKINS: Rachel, next slide. Next 19 slide.
20 MR. LATTA: Yes, one more slide. Thank 21 you.
22 So, this is Ryan Latta speaking now.
23 So, as a point of reference for the FHR, 24 which is the application of the fuel, we have this 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
14 slide. And so, we have two reactors here. There is 1
Hermes Test Reactor, which is a non-power test 2
reactor, and there's, farther down road, future KP-X, 3
which is a commercial electric power reactor.
4 The kind of characteristics of the reactor 5
are given here. Flibe coolant, graphite reflector.
6 All of them use the same fuel on the design, which is 7
a pebble fuel containing TRISO fuel particles.
8 The power of the Hermes, 35 megawatts, 9
thermal; KP-X, 10 times greater in power. Both are 10 low pressure systems, have low pressure systems below 11 200 kPa. Inlets, 550 C, and outlets, 620 to 650 C.
12 And on the right is a schematic of the 13 reactor. You can see the vessel outlined. There's a 14 white space between the inner cavity where the pebbles 15 are contained, which is the core, and the graphite 16 reflectors outside of that, and then, the vessel wall.
17 And so, the pebbles are contained within 18 that inner cavity. They're in a packed-bed formation 19 with Flibe coolant flowing from top to bottom and from 20 bottom to top in the reactor. And the pebbles also 21 enter in the bottom at the fuel chute, and then, they 22 exit the reactor at the defueling chute at the top of 23 the reactor.
24 And so, the pebbles are buoyant in the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
15 Flibe coolant and the bed itself is in a packed 1
configuration, and the pebbles move very slowly over 2
time through the core, and then, are recirculated and 3
inspected, and then reintroduced into the bottom of 4
the core until they reach their limits, specifically, 5
for burnup.
6 MR. TOMKINS: Any questions on that>?
7 Okay. So, next slide.
8 MR. LATTA: Okay. This is a little 9
schematic of the annular fuel pebble and the TRISO 10 fuel particle. The TRISO particle shown here is 11 typical of what you have seen before, a UCO kernel 12 with multiple coating layers of PyC, and then, a SiC 13 layer.
14 The fuel particles are contained within 15 the fuel pebble -- this pebble, specifically 40 16 millimeters in diameter, which is the size of a ping 17 pong ball. Special to this design is that the pebble 18 has three regions. There's an inner region that is a 19 lower density than the rest of the matrix material.
20 Then, there's a fuel region that contains 21 the TRISO particles, and then, outside the fuel region 22 there's a shell that's free of fuel and that separates 23 the fuel from the surface of the pebble.
24 Next slide, please.
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16 MEMBER REMPE: This is Joy.
1 MR. LATTA: Uh-hum?
2 MEMBER REMPE: Can we go back to the prior 3
slide, please?
4 You're right, we've seen this before. But 5
this pebble and the way it's fueled is different than 6
the German fuel because of this low density core 7
region. But are there other differences? Are the 8
pebbles packed more closely than the German fuel? And 9
this fuel-free outer matrix shell, how does that 10 differ from what we've seen in Germany or what's being 11 done in China, for example?
12 MR. LATTA: Sure. So, I will go over the 13 differences.
14 So, first off, the pebble is smaller in 15 diameter. It's 40 millimeters versus 60 millimeters.
16 We have this interior lower density core, and that's 17 to allow the pebble to be net buoyant within the 18 Flibe. That does not exist in the historic German 19 pebble.
20 The fuel region contains a higher packing 21 fraction of particles than historically have been done 22 with German pebbles, but it's consistent with what has 23 been done with compacts, and specifically, with AGR 24 compacts.
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17 The fuel-free outer shell is thinner in 1
dimension than has historically been used in the 2
German pebbles.
3 MEMBER REMPE: Thank you.
4 At some point, I guess I'd be interested 5
in how you feel comfortable that this tighter packing 6
is not going to damage the coatings of the particle.
7 MR.
LATTA:
Sure.
So, in the 8
manufacturing/development program we have, we'll be 9
fabricating these with surrogate materials and proving 10 through deconsolidation-leach-burn-leach after 11 fabrication that the defect fraction of particles 12 post-fabrication are within the specifications. So, 13 we'll be able to demonstrate through sampling of 14 product that we meet our specification.
15 MR. TOMKINS: And the particles are 16 overcoated. So, they have a built-in, you know, 17 separation, if you will.
18 MR. LATTA: Yes. So, all particles are 19 overcoated, and then, poured into these molds to 20 fabricate and press this region. And so, there's 21 specifications on that as well to ensure that those 22 things are met.
23 MEMBER REMPE: So, remind me what this 24 overcoating is composed of? And do you have any 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
18 irradiation data to show how it works? I mean, that 1
was not done in the AGR tests, right?
2 MR. LATTA: It was done. So, overcoating 3
is --
4 MEMBER REMPE: Oh, it was done? Okay.
5 MR. LATTA: Overcoating is a traditional 6
method for packing and keeping particles separated 7
from one another through many of the programs that 8
exist, you know, internationally or domestically.
9 So, you roll the particles in the matrix 10 material. All the matrix material, the three zones, 11 is the same material. It just has, you know, either 12 has a lower density from having more -- fabricated 13 with more porosity or it's fabricated with TRISO 14 particles embedded in it.
15 MEMBER REMPE: Is the packing fraction 16 tighter than what was done in AGR-1 compacts?
17 MR. LATTA: No, it's within that range.
18 MEMBER REMPE: Okay. Thank you.
19 CHAIR PETTI: So, Ryan, since this was 20 brought up -- I was going to bring it up later --
21 MR. LATTA: Okay.
22 CHAIR PETTI: -- deconsolidation-leach-23 burn-leach is not a perfect QC technique. And the 24 concern in pressing is (a) you're right, breaking 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
19 particles, but (b) partial cracks in layers that would 1
pass through the QC, and the cracked particles, under 2
irradiation, the cracks potentially growing. This is 3
just one of the concerns I have with the qualification 4
approach. As we get into it a little bit more maybe 5
later in the presentation, or even in the closed 6
session, we can talk some additional details.
7 MR. LATTA: Okay. Thank you.
8 MR. TOMKINS: Okay. Next slide.
9 MR. LATTA: Okay. I was just going to go 10 through these parts more individually, as I've already 11 done a little bit just before.
12 So, the kernel is a UCO kernel. It's a 13 mixture of UO2 and uranium carbide phases. So, this 14 is where the uranium is and where the fission occurs, 15 and the fission products are generated. Outside of 16 the UCO kernel is a porous carbon buffer layer. This 17 layer kind of serves as the plenum for fission product 18 gases generated in the kernel and, also, mechanically 19 separates the kernel from the structural PyC and SiC 20 layers.
21 On top of that is the IPyC layer. So, 22 this is the first real structural layer and barrier, 23 fission product barrier of the fuel particle.
24 You can go to the next slide.
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20 MR. TOMKINS: Rachel, next.
1 MR. LATTA: So, after the IPyC is the SiC 2
layer. So, this is a silicon carbide layer that is 3
the primary structural layer and fission product 4
barrier to prevent fission product release.
5 The next layer on top of that is the OPyC 6
layer. This is kind of the final and secondary layer 7
of barrier for fission product retention structural 8
barrier or structural component of the particle.
9 And then, finally, as we had just 10 described, in fabrication, you overcoat the particles, 11 and then, they're pressed into the fuel region to 12 obtain your nominal packing fraction.
13 MR. TOMKINS: Okay. Next.
14 MR. LATTA: And now, talking about the 15 features of the pebble design itself.
16 So, first off, going from interior to 17 exterior, on the interior is the low carbon core, low 18 density carbon core. And so, the objective of this 19 core is that is reduces the overall density of the 20 pebble, so that it is net buoyant in the Flibe 21 coolant.
22 Then, outside of that region is a shell of 23 fuel-containing matrix material. And so, the 24 advantage of this is that the fuel is moved to the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
21 outside of the pebble, and this lowers the fuel 1
temperature for a given power rating versus if the 2
fuel was uniformly distributed throughout the whole 3
pebble. So, this helps you obtain higher power 4
density, lower temperatures in an FHR.
5 And then, finally, there's the fuel-free 6
outer shell. And so, this is a region of the same 7
matrix material that separates the fuel region from 8
the Flibe or exterior environments and protects the 9
fuel from mechanical damage.
10 MEMBER BALLINGER: This is Ron Ballinger.
11 I have a question relating to the low 12 carbon density core. How much margin do you have, or 13 does it really matter, where if you get a change in 14 density pebble-to-pebble, it alters the migration rate 15 through the core? Is that an issue?
16 MR. LATTA: You're worried about migration 17 of fission products through the core?
18 MEMBER BALLINGER: No, no. Migration of 19
-- excuse me -- movement of the pebble, of the fuel 20 pebble itself through the core.
21 MR. LATTA: Oh, yes. Okay. So, we do 22 expect the pebble to densify with accumulated fluence.
23 There's also a distribution of allowable densities 24 from the fuel specification, and the density of the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
22 pebble is set relative to the Flibe density, such that 1
it would be able to maintain positive buoyancy even 2
with the extreme bounding conditions of what the 3
density could become with irradiation.
4 MEMBER BALLINGER: So, I guess when you 5
measure the burnup of pebbles that exit the core 6
against what you might expect it to be, you would 7
notice if there was something funny going on?
8 MR. LATTA: We would also be performing an 9
inspection. So, there would be a visual inspection of 10 the pebbles, and we would be able to examine the 11 diameter of the pebble through that process.
12 MEMBER BALLINGER: No, no. I guess what 13 I was saying was you anticipate by analysis, or 14 whatever, that the pebble that exits the core has a 15 certain burnup, and then, you measure it and you 16 discover that the burnup is actually X plus or minus.
17 Is that an indicator that the pebble has migrated 18 through the core at a different rate than expected?
19 MR. LATTA: It could potentially be. If 20 the burnup was significantly larger than expectation 21 or significantly lower, then that could be an 22 indication that the pebble had traversed either 23 slowly --
24 MR. TOMKINS: By the way, these pebbles 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
23 move kind of en masse. I mean, there isn't that much 1
room in there. So, you're not going to have one 2
pebble that speeds ahead of the others. We've done 3
visuals of this process.
4 MEMBER BALLINGER: Okay. All right.
5 Okay. Because I recall an experiment that Andy Kadak 6
did a very long time ago where he mixed the colors of 7
the pebbles and looked at the migration rate through 8
the core, and the density did make a difference in 9
that case -- yellow and red and green pebbles, believe 10 it or not.
11 MR. HACKETT: And we do expect a 12 distribution in the migration pathway for the pebbles 13 anyway, and we're accounting for that. And that's the 14 reason why we do the pebble inspection, to ensure that 15 the pebbles are extracted within the expected burnup 16 range that we have, the limits that we have for 17 burnup.
18 MR. TOMKINS: By the way, that was Micah 19 Hackett, who is our Director of Fuel and Materials.
20 MEMBER BALLINGER: Thank you.
21 MR. TOMKINS: Okay. Next slide.
22 MR. LATTA: So, one more slide, please.
23 All right.
24 So, this is an outline of the sections of 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
24 the methodology. I'll go through each one of these 1
points more in-depth through the next series of 2
slides.
3 To start out with, they're just talking 4
about historical experience and ties to AGR and the 5
EPRI TRISO Topical Report, and discuss an internal 6
PIRT we perform for the fuel pebble and TRISO 7
particle, and discuss more on manufacturing after 8
that, the specification and QC to control quality 9
through inspection.
10
- Next, I'll talk about the fuel 11 qualification envelope and operating range for the 12 fuel, and what we do to be within that or external to 13 that.
14 Next slide, please.
15 MEMBER REMPE: This is Joy.
16 And actually, I think it fits better on 17 that prior slide. I had a couple of questions that 18 are, I think, at a higher level.
19 Again, it's related to whether you decide 20 you want to do an irradiation test, and if the 21 operation is going to be within the bounds of the 22 qualification envelope.
23 Say Hermes doesn't need to have additional 24 irradiations, but you think the larger one might 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
25 because of something or other. And I guess I'm 1
curious on the something or other, because don't you 2
need validated codes to determine that, and will you 3
have the codes validated for the larger plant? Or 4
even for Hermes to decide that you don't need it, are 5
the codes validated? So, I'm wondering if it's a 6
roundabout argument to decide I don't need irradiation 7
data.
8 And then, the second question I had is, 9
where would the irradiation -- I mean, I saw in the 10 text it talks about the facility and it seems like 11 it's going to be of the whole pebble, not compacts, 12 and then, where would you do such a test? Because, as 13 I understand it, the High Flux Reactor is going to go 14 down in 2024 and they're having troubles with it. And 15 are you planning to go to Russia? Where would you do 16 such a test?
17 MR. TOMKINS: I don't know about Russia, 18 but --
19 So, the first question on the 20 qualification envelope, for the commercial reactor, 21 the particle power and the burnup are beyond the 22 limits we're holding ourselves to. So, we would, 23 presumably, have to do irradiation to address that.
24 MEMBER REMPE: And you're confident 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
26 because of what? What reason you won't have to do it 1
for Hermes, irrespective of Dave's concern? I'm just 2
wondering, did you need to have a validated computer 3
code to know you don't need to have it for Hermes?
4 MR. TOMKINS: Yes, but at the time we make 5
that judgment about whether we were within the fuel 6
envelope or not, we will have validated codes to 7
determine that.
8 MEMBER REMPE: Okay.
9 MR. TOMKINS: Or validated --
10 MEMBER REMPE: And the codes are? What 11 are the codes that are validated?
12 MR. TOMKINS: Well, we probably need 13 Brandon. Maybe you can help with that.
14 MR. LATTA: KP-BISON is our fuel 15 performance code. And so, part of this validation are 16 AGR-1 and AGR-2.
17 MEMBER REMPE: Okay. Part of it is, but, 18 then, I read the Topical Report, and I believe it's 19 even in our letter, that you plan to come back. Not 20 all the properties are well-defined for fully 21 validation. So, you are planning to get all the data 22 required to have that code validated before you go too 23 far in your licensing application? Or is it going to 24 be, I mean, it's a Construction Permit, so you go 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
27 ahead and build it, but you can't load the fuel. So, 1
you'll have to have data by that time to have the 2
validated code? I'm just kind of thinking about 3
this --
4 MR. HAUGH: I'm going to step in here.
5 This is Brandon Haugh, the Senior Director of Modeling 6
Simulation at Kairos. Thanks, Joy.
7 It depends on how you define validation, 8
right? So, we're defining validation within the 9
scopes of the predictability of the code to predict 10 the performance of our envelope, which is the AGR 11 envelope. We believe we have all the data to do that.
12 MEMBER REMPE: And is the staff onboard 13 with that assumption?
14 MR. HAUGH: They'll get a chance to review 15 that validation and concur, and that work is ongoing.
16 And they should get a chance to see that.
17 MEMBER REMPE: And so, we'll see the 18 validation, the fully validated Topical Report for 19 TRISO with KP-BISON before? Because I was just was 20 kind of going, well, nothing is going -- we've 21 discussed this before in our reviews of these Topical 22 Reports, the kind of preliminary reviews for the 23 methodology, but it's not totally -- or the approach 24 to the methodology. It's not a validated methodology, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
28 even though you have an approved --
1 MR. HAUGH: Sure.
2 MEMBER REMPE: -- a staff evaluation that 3
concurred. And so, again, I just want to make sure 4
everybody understands that.
5 And then, what's the answer to the 6
question about the facility where you're going to be 7
doing these irradiations of the pebble?
8 MR. TOMKINS: That might be a closed 9
session.
10 MEMBER REMPE: Oh, okay. That sounds 11 good. Thank you. Don't let me forget.
12 MR. TOMKINS: Yes. Nicole, can you kind 13 of note that, so we pick that up during the closed 14 session?
15 MS. SCHLICHTING: Sure.
16 CHAIR PETTI: This is Dave. I just want 17 the court reporter to note that Matt Sunseri, Member 18 Sunseri, has also joined. Thank you.
19 MR. TOMKINS: All right. Next slide.
20 MR. LATTA: Yes. So, we're going to 21 definitely go through the methodology, talking about 22 the fuel pebble laboratory testing. These are tests 23 to demonstrate that the pebble meets functional 24 requirements. In addition to that, there's fuel 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
29 irradiation testing that we'll go into, and then, some 1
connections with fuel performance modeling, and then, 2
finally, the fuel surveillance program for the 3
reactor.
4 And next slide. Advance one more, please.
5 Okay. This slide just talks to the long 6
history of experience with TRISO fuel and matrix 7
materials and fuel forms that have been demonstrated 8
in the U.S. and through international experience. The 9
TRISO fuel form was first introduced for gas reactors 10 in the 1960s.
11 A lot of attention in this case was given 12 to the German pebble reactor designs and use of pebble 13 fuel, and then, in addition to that, more recently, 14 China has gone down this road of licensing and 15 starting to operate two high temperature gas reactors.
16 And then, within the U.S., there was the 17 General Atomics experiences with a couple of prototype 18 reactors and carbides fuel and prismatic core.
19 And so, there's quite a long history of 20 many nations being able to set up fuel fabrication and 21 demonstration through irradiation testing, operation 22 of prototypes or demonstration
- reactors, the 23 capability of this technology, fuel technology, to 24 work within a gas reactor.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
30 And then, this kind of all culminates 1
within the U.S. through the AGR program, which built 2
on this extensive experience to develop a domestic UCO 3
TRISO coated fuel particle. And a large part of what 4
Kairos is proposing here leverages this DOE program 5
and the EPRI Topical Report on TRISO particles as a 6
foundational case for our fuel qualification.
7 Next slide, please.
8 MEMBER REMPE: This is Joy.
9 MR. LATTA: Yes?
10 MEMBER REMPE: Just on that, in the 11 Topical Report, I think there's a typo about the years 12 the THTR operated. So, you might want to fix that if 13 you're updating it at some point.
14 MR. LATTA: Okay. Thank you. We'll take 15 that down.
16 All right. This slide, it's a lot of 17 numbers, but the point of this slide is to talk to the 18 extensive amount of testing the DOE has been doing 19 with the AGR program.
20 And then, the bottom set of slides is a 21 comparison to German irradiation test data that was 22 also performed in test reactors. Whereas, the AGR 23 particles were tested as compacts, the German fuel was 24 tested in a pebble form. Historically speaking, the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
31 performance of German fuel had been considered kind of 1
the gold standard for excellent experience with TRISO 2
fuels, and then, the AGR program over the last many 3
years has been able to really demonstrate an 4
equivalence with that through the domestic testing 5
program.
6 So, this slide talks to the kind of 7
testing that was performed and the low failure 8
fractions that were demonstrated in the AGR program 9
and how that was then incorporated into the EPRI 10 Topical that was reviewed by the NRC and issued an 11 SER.
12 Then, next slide, please.
13 And then, to go on with that kind of data 14 we see in the literature and what has been done 15 recently with the AGR, there's also furnace safety 16 testing data with AGR compacts tested at a range of 17 temperatures of 1600 to 1800 C for hundreds of hours, 18 tens of thousands of particles tested between AGR-1 19 and AGR-2, showing fairly low failure rates and high 20 reliability of the TRISO particles.
21 In addition, historically, German fuel has 22 been tested under very similar conditions with UO2 23 TRISO particles but in pebble fuel form and, also, has 24 historically demonstrated excellent performance, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
32 especially up to the 1600 C range.
1 Okay. Okay. So, switching gears towards 2
the PIRT, Kairos Power conducted a PIRT on the two 3
main parts of the fuel, which are the pebble and the 4
fuel
- particle, and
- then, broke it down by 5
subcomponents, the regions within the pebble, the 6
layers and parts of the fuel particle. The 7
application for this was our reactor and its thermal 8
and radiation conditions. The scenarios were 9
fabrication operations and accident conditions, and 10 the PIRT was performed to identify high priority 11 phenomenon that are related to the figure of merit, 12 which was fission product transport and release.
13 And so, there was an internal PIRT 14 performed in Kairos, and then, an external PIRT 15 performed with subject matter experts. And these are 16 kind of now the main results of the PIRTs. There's a 17 graph on the right which shows kind of the number of 18 high-ranked phenomenon we observed for TRISO or 19 pebbles. There was almost 200 phenomenon identified 20 over the course of this PIRT.
21 For TRISO, there's a lot of high-level 22 knowledge related to this now. So, the highest ranks 23 were Rank 2, where it's high importance, and medium 24 knowledge level. And then, for the fuel pebble, we 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
33 saw much more diverse rankings, and these were mostly 1
related to the novel fuel design, manufacturing, and 2
performance of the annular fuel pebble.
3 Also to say that this PIRT really built on 4
this 2004 TRISO PIRT that was originally out there 5
kind as a foundation for starting this effort.
6 CHAIR PETTI: Ryan, just a point. If you 7
look at the date of that PIRT, 2004, that really 8
predates AGR.
9 MR. LATTA: Yes.
10 CHAIR PETTI: I think it was about a year 11 and a half in. And so, there were lots of things on 12 the table. I was in that PIRT. And if you reflect 13 back and look at everything from AGM back on that 14 PIRT, you probably would re-rank them significantly 15 differently. There were all sorts of issues that were 16 out there because of a lack of data that I think today 17 you would probably take some of them and rate them 18 lower in terms of their importance, given where TRISO 19 particles are today than they were in 2004.
20 MR. LATTA: Yes, and largely, what we did, 21 we took like the phenomenon, and then, we gave 22 everything brand-new ratings and rankings based on 23 present knowledge.
24 CHAIR PETTI: Ah, okay.
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34 MR. LATTA: And, you know, we have a 1
different application --
2 CHAIR PETTI: Right.
3 MR. LATTA: -- a different scenario. You 4
know, the pebble and some other things are different.
5 So, things were re-rated and ranked to reflect that 6
difference.
7 CHAIR PETTI: Ah, good. Thanks.
8 MR. LATTA: Thank you.
9 MEMBER REMPE: So, this is Joy.
10 And when I was reading the Topical Report, 11 I thought there was just a single PIRT. And my 12 question had been, are they internal and expert 13 people? It never identifies who participated.
14 I think what you just said in your 15 presentation was that you had an internal PIRT, and 16 then, you had an external one? But you must have 17 combined the results somehow? Could you elaborate a 18 little bit more about who you hired to bring in and 19 their years of experience? And if you had a single 20 internal one, who all -- I mean, did you just take 21 everyone in your fuels branch, or how did you do this?
22 MR. LATTA: Yes. So, the internal PIRT 23 was performed by the subject matter experts at Kairos, 24 and then, later, we included a set of experienced 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
35 subject matter experts that were external, whether 1
academic or related to the National Laboratories, to 2
get their input. And this was combined into a report, 3
and then, that report was seen by the NRC.
4 MR. TOMKINS: We can probably give the 5
name.
6 MR. LATTA: Can we give the name?
7 MR. TOMKINS: Yes.
8 MR. LATTA: Okay. Okay. So, I can go 9
with a list of names. The PIRT process was 10 facilitated by Chris Lamm.
11 MR. D. GARDNER: Hey, Ron? Hey, Ron, this 12 is Darrell Gardner.
13 I think we need to, if we're going to be 14 mentioning names, we need to be doing that in closed 15 session.
16 MR. LATTA: Okay. We could save that for 17 the closed session.
18 MEMBER REMPE: That would be great. And 19 then, I guess if there is a report that actually has 20 the PIRT report, and you did share it with the NRC, 21 could we ask you share it with us?
22 MR. D. GARDNER: The PIRT was not 23 submitted on the docket.
24 MEMBER REMPE: Okay. So, we're not 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
36 allowed to see it?
1 But, yes, please share the names, then, in 2
a closed session.
3 MR. LATTA: Okay.
4 So, next slide, please.
5 Okay. And so, the objective of the PIRT 6
is to understand where you have high importance and 7
medium or low knowledge level, and there you know the 8
phenomena that you really need to investigate as far 9
as your fuel qualification program.
10 So, through that process, this slide just 11 talks to the main things that were found in the PIRT 12 that need to be addressed. And so, there were, 13 obviously, manufacturing/development-related issues 14 with the pebble, since this was conducted a few years 15 ago now, and the objective was that we would have 16 manufacturing/development, obviously, and be able to 17 leverage German and AGR program experience in that 18 process.
19 And
- then, for fuel qualification, 20 specifically, things related to the pebble and its 21 performance to meet functional requirements, there was 22 a series of mechanical and material compatibility-23 related phenomenon we would like to investigate. And 24 so, a fuel pebble laboratory testing program was 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
37 created to address those issues.
1 MR. BLEY: This is Dennis Bley.
2 Either you -- or it's really a question 3
for staff, or maybe Weidong can follow up -- if PIRT 4
was not submitted on the record, did the staff do an 5
audit and is there an audit report on the PIRT?
6 Weidong, you can follow up with the staff 7
later on that. We don't need to talk about it here.
8 MR. WANG: Okay. Will do.
9 MR. LATTA: Okay. Move on to the next 10 slide, please.
11 Okay. So, this slide talks to the 12 specification, manufacturing, and quality control.
13 So, the TRISO particle specification used 14 in our reactor is equivalent to the AGR in AGR-5/6/7 15 specifications. It largely draws from this and we're 16 trying to replicate the fuel that was generated and 17 used for AGR-2 as a way to leverage the irradiation 18 test data and the AGR-2 program and review of the EPRI 19 TRISO Topical. The TRISO specification draws on and 20 is similar to historic ACGR fuel pebbles with special 21 features, as we have discussed, for FHRs.
22 And
- then, discussing manufacturing, 23 kernels are fabricated through a sol-gel process to 24 create microspheres. Particles are coated through a 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
38 continuous CVD process, and then, pebbles are formed 1
from a mixture of graphite powders and binders and 2
with incorporated TRISO fuel particles impressed in 3
the shape and heat-treated. So, these are kind of 4
traditional methods and forms of manufacturing that 5
have been used in the past, but apply to our specific 6
application.
7 And then, beyond that, is the inspection 8
of product to demonstrate that the product meets 9
compliance to the specification we previously 10 mentioned.
11 Next slide, please.
12 CHAIR PETTI: Ryan?
13 MR. LATTA: Yes?
14 CHAIR PETTI: A question. Why don't you 15 go back?
16 MR. LATTA: Sure.
17 CHAIR PETTI: The AGR-2 and 5/6/7 18 particles were enriched at a little over 14 for AGR-2 19 and I think a little over 15 for 5/6/7. Is that the 20 enrichment levels you are going to go with or are you 21 going to go up to the LEU limit?
22 MR. LATTA: Yes. No, we go up to the LEU 23 limit, and that's about the only real difference 24 between --
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
39 CHAIR PETTI: Right. And then, you're 1
going to try to get to complete burnup, if you will?
2 And that's what puts you out of, sort of in this --
3 AGR-1 went to those limits, but it was a small kernel.
4 These are bigger kernels than AGR-2, and that's where 5
you feel you may need testing for the --
6 MR. LATTA: Yes, yes. And so, we had 7
recognized that.
8 CHAIR PETTI: Yes.
9 MR. LATTA: And that is explained within 10 the Topical for the reasoning. And AGR-5/6/7 was the 11 larger particle, but it never reached to the 19-12 plus --
13 CHAIR PETTI: Right, yes.
14 MR. LATTA: So, we're sticking with AGR-2 15 now, which was also previously reviewed, as you know.
16 CHAIR PETTI: Yes. Okay.
17 MR. LATTA: Okay. Next slide, please.
18 Okay. This just talks of quality control.
19 There's a list of components of the particle and 20 pebble, and it kind of just lists the different kinds 21 of inspections that will be performed. There's a 22 significant amount of characterization and inspections 23 that are performed through the fabrication process to 24 demonstrate the product meets the specifications.
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40 That's a very important part of fabrication, to 1
demonstrate and prove that the product meets the spec.
2 Okay. Okay. So, it addresses the 3
qualification envelope. So, for fuel operated in the 4
reactor, there are really four key parameters related 5
to fuel performance that we identified: power, 6
burnup, temperature, and fluence.
7 And so, operating under steady-state 8
conditions, there's an operating envelope, and then, 9
an envelope for temperature under transient 10 conditions. And so, in the Topical, what we proposed 11 in there has been that the qualification envelop is 12 really the AGR-2 irradiation conditions, as defined by 13 the TRISO Topical Report. As long as you're able to 14 demonstrate that you're operating within that 15 envelope, the fuel is qualified for these irradiation 16 conditions. If your reactor needs to operate outside 17 of those conditions, then you would need to collect 18 additional irradiation test data.
19 If you can advance to the next slide, 20 please?
21 And so, this is a
table of the 22 qualification envelope and example conditions for the 23 Hermes non-power, and then, the KP-X Power Reactors.
24 On the right -- or excuse me -- on the left are the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
41 four parameters we have just discussed, and then, 1
temperatures, and also, temperatures below that for 2
postulated events. The first are for normal 3
operations. And so, the proposed qualification 4
envelope for normal operation matched conditions that 5
were observed in the AGR-2 irradiation.
6 And then, you need to go to the next 7
column which are examples of Hermes conditions. As 8
you can see, the temperatures, burnup power, and 9
fluences are less, and sometimes significantly less, 10 than the operating envelope.
11 And then, as you go to the right, you see 12 KP-X in the final column, the conditions are higher, 13 and some of them exceed -- specifically, power and 14 burnup and fluence is a little bit higher than the 15 operating envelope.
16 So, you can see there's a difference 17 between Hermes, which should be able to operate within 18 the operating envelope of AGR-2, while KP-X would be 19 outside of this operating envelope and require 20 irradiation testing.
21 Okay. So, moving on to a different part 22 of fuel qualification. This is the laboratory test 23 program. So, no irradiation involved in this case.
24 And so, the objective is to demonstrate that annular 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
42 fuel pebbles meet the functional requirements, and 1
this is through a series of mechanical-related tests 2
and material compatibility tests in a laboratory 3
environment.
4 Okay.
5 MEMBER REMPE: So, this is one where I'm 6
curious, I guess, along with what Ron was talking 7
about. I just really am wondering what the basis is 8
to know that radiation won't affect molten salt 9
infiltration with cracking. I know you're going to be 10 looking for cracking, but the depth of cracks, as the 11 pebbles are going in circulation. I just am wondering 12 if there's a good, strong basis for saying we don't 13 need to do testing to assess the combined effects.
14 MR. LATTA: Sure. So, you would less 15 expect cracks to open up with irradiation, more to 16 close with irradiation indensification. The fluences 17 are fairly low, especially for Hermes, going in.
18 Infiltration is more related to the width of the pore, 19 or I guess in that case it could be a crack, the crack 20 width. But you would need to also infiltrate a 21 significant amount of Flibe coolant to lose buoyancy.
22 MR. TOMKINS: Right. And the Chinese 23 casting showed that you didn't have infiltration up 24 to, I think it was 600 kilopascals. And we're 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
43 operating at 200. So, we've got that background as 1
well.
2 MR. LATTA: Yes.
3 CHAIR PETTI: So, can I just ask, in terms 4
of the testing, particularly on the compatibility and 5
the infiltration, will you use sort of a tech spec 6
limit of impurities? You know, in a lot of these 7
systems I know that the chemical compatibility of 8
graphite with air and steam is strongly dependent on 9
impurities that are present in the graphite. And so, 10 I could imagine that the impurities might have an 11 effect.
12 MR. LATTA: Yes, I think for material 13 compatibility, if you think back to MSRE, where the 14 fuel was dissolved into the Flibe, and you had a whole 15 series of fission products and other transition metals 16 and materials from the structurals, you still didn't 17 see degradation of graphite or graphitic materials in 18 Flibe, and that, thermodynamically, and the way we 19 plan to run this reactor with fairly clean salt, that 20 we would not expect to see much interaction at all 21 between graphite and Flibe.
22 CHAIR PETTI: Since we're here on 23 compatibility -- and you can decide to answer in the 24 closed session -- I am concerned about some of the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
44 stuff that will be corroded out of the steel by the 1
salt. And, in essence, you've set up a chemical pump, 2
right? There's an equilibrium concentration at the 3
hot end and an equilibrium concentration at the cold 4
end, and you'll get some Delta T mass transfer, and in 5
between the hot and the cold is this large pebble bed 6
with a huge amount of surface area. And what I'm 7
worried about is the iron-chrome-nickel in the salt 8
getting into the pebble and attacking the silicon 9
carbide.
10 Iron, chrome, and nickel, as you probably 11 are aware, must be as far away from this fuel as 12 possible. In a gas reactor, the closest of that is 13 the Kobel, and it's in a solid state, very far away 14 from the fuel.
15 If you've read some of the AGR-2 papers, 16 you'll find that a thermocouple wire -- a thin, tiny 17 thermocouple wire -- attacked silicon carbide, and 18 that was a nickel wire.
19 You can go and read the literature, that 20 there is strong chemical interactions between iron, 21 chrome, and nickel and silicon carbide. And you're 22 going to operate for, you know, thousands of hours 23 with a certain concentration in the salt that could be 24 picked up by the pebbles and could attack the silicon 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
45 carbide.
1 It would seem to me, since you mentioned 2
you were going to make some surrogate pebbles, that 3
you could test this in a Flibe loop -- you wouldn't 4
have to have a uranium-containing pebble -- and see 5
what sort of interactions you would actually get.
6 MR. LATTA: Yes. So, I completely 7
understand this concern. And there's a number of 8
barriers between Flibe, you know, Flibe on the 9
exterior that might contain transition metals and 10 Flibe getting into the silicon carbide layer.
11 First off, there would have to be 12 infiltration of the Flibe into the fuel region, which 13 is separated by the fuel-free region in the pebble.
14 So, your pressure would have to get fairly high.
15 Operating pressures are below 200 kPa, and as far as 16 we know, infiltration should begin above 600 kPa. So, 17 there's a pressure that would have to drive Flibe into 18 that region.
19 Secondly, if the Flibe got into the fuel 20 region, you would still have OPyC protecting the 21 silicon carbide, and then, if that barrier were not 22 there, you would still have to have an exchange of 23 Flibe-containing transition metals to feed a reaction.
24 So, there's a number of barriers that are in place to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
46 prevent this kind of a reaction.
1 MR. TOMKINS: Also, we're inspecting 2
pebbles every 50 days or so. We could see --
3 CHAIR PETTI: Well, you're not going to be 4
able to see the silicon carbide.
5 MR. LATTA: But you might be able to --
6 there's a potential opportunity to determine if Flibe 7
could be getting into the pebbles that are inspected.
8 CHAIR PETTI: Yes, we had all these same 9
arguments in AGR, and I'll just tell you that the 10 program thought that thermocouples 3 millimeters away 11
-- there was graphite between the thermocouple and the 12 compact, and there was overcoat between the compact 13 and the powder coats, and the nickel got there. Okay?
14 So, I understand all these technical 15 arguments for barriers, but chemistry is funky stuff.
16 MR. LATTA: Yes.
17 CHAIR PETTI: And the chemical potential, 18 those transition metals want that silicon carbide, and 19 they seem to make it there.
20 MR. LATTA: Yes. We're also at a lower 21 temperature, which also --
22 CHAIR PETTI: I understand that. Yes, we 23 don't know the kinetics. You know, it hasn't been 24 studied systematically or anything. But --
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47 MR. LATTA: Sure. Okay.
1 MEMBER REMPE: So, to follow up on your 2
response about the Chinese data, talk to me more about 3
the Chinese data and what they obtained. You're just 4
talking about their pebble bed reactor, which used 5
helium as the coolant, right?
6 MR. LATTA: No. We're talking about five 7
infiltration tests. There's an ASTM standard for 8
molten salt infiltration testing and the structural 9
graphite and carbon matrix material. And so, as part 10 of this laboratory test program, we have a setup to 11 perform an experiment according to this ASTM standard.
12 And Oak Ridge researchers have been trying 13 to also perform these tests with, I believe, Flibe and 14 Flinak on a series of structural graphites and carbon 15 matrix materials. And they've been able to 16 demonstrate at what pressures you reach a threshold 17 for infiltration of salts into the porosity of these 18 graphites.
19 MEMBER REMPE: Okay. So, this was just 20 part of their molten salt program, not the program 21 that was discussed earlier on slide 14?
22 MR. LATTA: No. And Oak Ridge has also 23 been doing this kind of work. They have a setup in 24 Oak Ridge to perform these kinds of tests. And now, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
48 we have a setup here to do this as well.
1 MEMBER REMPE: Okay. Thank you.
2 MR. LATTA: Yes. Thank you.
3 Next slide, please.
4 Okay. So, this slide just talks to the 5
type of mechanical and anthropology testing that's 6
been performed. The objective is to demonstrate that 7
pebbles do not fracture from static or dynamic loads 8
in the reactor, and that wear is accept over the 9
pebble's lifetime.
10 And so, there is compression testing, 11 crush tests to demonstrate the load at which a pebble 12 would fail. There's impact testing. So, cyclic 13 impact tests to demonstrate when a pebble might 14 fracture or chip. And then, tribology testing that 15 measures the wear rate in different environments and 16 under different loads and the coefficient of friction.
17 Okay.
18 MEMBER REMPE: Again, wouldn't you expect 19 that pebble fracture would occur much more easily 20 after it had been irradiated?
21 MR. LATTA: The data actually shows the 22 strength increases with irradiation and with the 23 temperature.
24 MEMBER REMPE: So, what about brittleness?
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49 MR. LATTA: The load is increased -- the 1
allowable load increases with temperature and 2
irradiation. The load results in fracture. They're 3
fairly comparable. You know, you see about 2 to 3 4
millimeters of displacement before fractures. It's 5
generally been observed in these pebbles, whether 6
irradiated or not.
7 MEMBER REMPE: Okay.
8 MR. LATTA: They're porous. So, they kind 9
of crush a little bit before they fracture.
10 MEMBER REMPE: Okay.
11 MR. LATTA: Okay. And then, going on, 12 there's Flibe infiltration and buoyancy testing. So, 13 this is where you put a pebble, as we previously 14 explained, you put a pebble in a bath of Flibe under 15 pressure at temperature and you measure its weight 16 change before and after the test to investigate when 17 and under what condition or pressure you would see 18 Flibe infiltrate into the pebble. As I said, these 19 tests have been previously performed by Chinese 20 researchers and at Oak Ridge.
21 The test is really a mechanical test, but 22 there's also a Flibe compatibility portion of that 23 test, where you might run the test for thousands of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to demonstrate interaction between the carbon 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
50 matrix material and the Flibe salt.
1 The other compatibility test is with air, 2
and in this case, we're looking at oxidation rate of 3
the matrix material under a range of temperatures from 4
400 to about 700 C. And you're measuring mass loss 5
with time to create an equation to demonstrate that, 6
first of all, the pebble under normal conditions 7
should not interface with oxygen. It should be 8
largely in an inert environment. But, under safety 9
conditions, you could be concerned with oxidation with 10 overt air into the system.
11 CHAIR PETTI: Ryan, you probably know, but 12 there has been data developed under, I think, 13 university grants at DOE looking at oxidation of 14 matrix material with air. So, it would be a nice 15 comparison.
16 MR. LATTA: Yes, thank you. And that's 17 all we're trying to do, is demonstrate equivalence of 18 our materials with existing data or use a model.
19 CHAIR PETTI: All right.
20 MR. LATTA: Okay. And then in the topical 21 we have defined acceptance criteria for each of these 22 tests related to specific parameters. These are kind 23 of the non-proprietary definitions of the acceptance 24 criterias. So for mechanical testing of compression 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
51 and impacts it's really about demonstrating that the 1
loads within your reactor system are allowable 2
compared to the data you've collected. For tribology 3
it's about wear rate to demonstrate that the outer 4
fuel-free zone of the pebble is adequate to prevent 5
mechanical interaction of TRISO particles out -- with 6
something outside of the pebble.
7 Next slide, please? Going down the list 8
there's the buoyancy testing, so about density and 9
whether there's Flibe infiltration or not and then 10 material compatibility related to interaction of Flibe 11 or air with the pebble and demonstrating that there's 12
-- what damage might occur or that you're preventing 13 damage under normal operation.
14 Next slide, please? Okay. So this slide 15 talks to irradiation testing. So when we looked at 16 the fuel operating envelope we discussed if you were 17 inside AGR-2 irradiation conditions would be 18 acceptable, but if you were outside of that you would 19 need to perform an irradiation test. So this part of 20 the methodology defines what that irradiation test 21 would be. It would be irradiation of fuel pebbles or 22 fuel pebble design with -- in a non-KP-FHR facility, 23 very similar to the AGR irradiation test with fission 24 product measurement and PIE to determine particular 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
52 failure fractions. And then we defined an acceptance 1
criteria for the particle failure fraction that would 2
result in what we consider high-quality fuel for use 3
in FHRs.
4 Okay.
This slide talks to fuel 5
performance and the models that interface with either 6
analysis or data we've collected. KP-BISON, as you 7
know, is our main fuel performance model for analyzing 8
normal operation and transience, so this is connected 9
to the AGR validation. We performed an irradiation 10 test that -- we would also be validating this model to 11 that irradiation test. Additional model interfaces 12 are the modeling of the pebble bed. This informs wear 13 behavior and loads in the bed. And then the final is 14 finite element modeling of a pebble where we could 15 examine temperatures or mechanical behavior of the 16 pebble.
17 Okay. Fuel surveillance program. So with 18 the rest of the program completed and your -- get your 19 operating license and you're operating your reactor 20 there would be a fuel surveillance program to confirm 21 fuel performance in Hermes. And so the three 22 components of this program are fissure product 23 monitoring first to cover gas and Flibe coolant.
24 Then there's the PHHS, which is the pebble 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
53 handling and storage system. There will be an 1
inspection system that checks for burnup and examines 2
the physical condition of the pebble. And this 3
happens as the pebble -- the pebble goes through the 4
core multiple times, up to on -- well, up to an 5
average around six times through the core. So each 6
time it goes through it would go through this PHHS 7
inspection process.
8 And then finally there would be post-9 irradiation examination of pebbles from Hermes and 10 then the initial commercial reactor. And key things 11 would be examining our -- the TRISO particle failure 12 fractions, the amount of wear on the pebble surface 13 and whether we're seeing any amount of molten salt 14 infiltration into the pebbles after they have reached 15 their equilibrium burnup end conditions.
16 CHAIR PETTI: Ryan, go back for a minute.
17 MR. LATTA: Yes?
18 CHAIR PETTI: You guys may have done some 19 modeling on this, but the sorptivity of the cesium and 20 strontium in the graphitic matrix is very strong and 21 the Flibe coolant may not see significant changes in 22 those two isotopes' concentrations if something were 23 happening where the silicon carbide was degrading and 24 you didn't know it. It would be interesting; and you 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
54 can model all this, because I think you guys have to 1
tools, to see what a step increase in release of 2
cesium would mean in terms of transport through the 3
pebble and the coolant and can you see a significant 4
increase in the concentration of the coolant?
5 I've not looked at the chemistry, but it 6
is something to -- worth noting as you're thinking 7
about setting up limits and the like.
8 MR. LATTA: Thank you for that comment.
9 CHAIR PETTI: So let me here -- before you 10 go to summary, let me talk about my other concern.
11 I think you and I have different 12 definitions of fuel qualification. Your definition is 13 necessary for sure, but I don't think it's sufficient.
14 The irradiation proof testing is at the heart of every 15 TRISO program worldwide.
16 The Germans did it for pebbles called HFR 17 K5 and K6. Well after pebbles were being irradiated 18 in AVR they did these tests at Petten.
19 The Japanese took their compacts, tested 20 them in a reactor in Japan. Wasn't a really strong 21 reactor, so they came out to Oak Ridge and tested at 22 the HFIR.
23 The Chinese irradiation-proof tested the 24 pebbles they made in Russia for their 10 megawatt test 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
55 reactor at Beijing and then subsequently irradiated 1
tested -- proof tested pebbles off the production line 2
for the pebble bed that's in commercial operation.
3 And of course the U.S., that's what AGR-4 5/6/7 in the DOE Program is about.
5 And the reason for the proof testing is 6
because specs aren't perfect and you never know 7
everything. And that's why you do these things. And 8
there's tons of history across fuel development 9
programs beyond TRISO where people made, quote, small 10 changes and it had a deleterious effect on the fuel.
11 I would say that this pebble is unique.
12 I know that the topical report says it's like a German 13 pebble. I find it very different in a lot of 14 different ways. The free zones, the high packing 15 fraction, and the pressure that you'd have to press a 16 pebble is much, much higher than when you press a 17 compact.
18 And that plus the fact that the QC may not 19 catch everything in my mind suggests that there needs 20 to be irradiation testing, not that it has to be 21 completed before you're operating Hermes, but that if 22 you were sure that the burnup and fluence stayed ahead 23 of what was in Hermes, you'd at least have some 24 indication that this process of making pebbles out of 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
56 production scale you didn't bring something in that 1
you didn't foresee in the manufacture and that wasn't 2
captured by the QC.
3 MR. TOMKINS: Could we respond to that, 4
David? That was a good comment.
5 CHAIR PETTI: Sure.
6 MR. HACKETT: David, this is Micah 7
Hackett. I'll take a part of that at least. We 8
recognize that if we were to press spherical pebbles 9
in the same way in which for example the German 10 program pressed them, yes, very high pressures would 11 be needed to press those pebbles. So we have 12 developed an alternate method of being able to press 13 pebbles. And we're going to be using a hot press 14 process instead of a
cold process.
15 What that means is we use far less force and 16 being able to press our spherical compacts. So that 17 should, we believe, that greatly diminishes the amount 18 of energy needed to press that pebble and also should 19 prevent damage to the TRISO particles.
20 21 CHAIR PETTI: So you're going to -- the 22 resin will activate in the pressing?
23 MR. HACKETT: Correct.
24 CHAIR PETTI: Is it hot pressing or is it 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
57 warm pressing? Do you know the different --
1 MR. HACKETT: Yes.
2 CHAIR PETTI: I mean I don't want to get 3
into proprietary, but --
4 MR. HACKETT: Yes, maybe let's talk about 5
it more in the proprietary session.
6 CHAIR PETTI: Okay. Yes. Yes.
7 MEMBER BALLINGER: Yes, this is Ron 8
Ballinger. I thought about this also, but I'm 9
struggling whether I would consider the differences 10 that might -- that we see a potential safety risk or 11 a commercial risk. And so I haven't decided whether 12 I think that's true, but isn't that the question that 13 we're talking about here? If it's simply a commercial 14 risk, well, some days chicken, some days feathers.
15 But if it's a safety risk, that's a whole different 16 ball game. And I guess I would certainly defer to 17 Dave's judgment there because he has all the 18 experience.
19 MR. TOMKINS: So, Dave, I think you said 20 that if we were to do an irradiation program, it might 21 not be needed for Hermes, but it would be needed for 22 APX, the power reactor. Is that what you said?
23 CHAIR PETTI: No, I said that you didn't 24 have to have the irradiation complete to get the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
58 operating license, that you just had to have the 1
irradiation stay ahead of where you were in the 2
reactor itself.
3 MR. TOMKINS: All right. Because the test 4
reactor is obviously a test reactor, right, or you 5
know, it's to test things. And certainly that can be 6
a foundation for what we do in the commercial reactor, 7
which is coming to come behind it.
8 CHAIR PETTI: Right.
9 MR. LATTA: Additionally versus a gas 10 reactor we have the FliBe coolant as a containment 11 outside of the fuel itself.
12 MR.
TOMKINS:
- Right, which is a
13 significant difference. The other thing is our margin 14 to any kind of limits is very large. I mean we are 15 way far away from the 1,600 for transient and from the 16 1,360. So --
17 CHAIR PETTI: Yes, I'm not at all worried 18 about a performance issue. I'm worried about 19 particles failing in PIE that were unanticipated 20 because of something done in fabrication that was 21 missed.
22 So I mean, if you go back through and you 23 read the EPRI Topical Report, they'll talk about what 24 happened in the new production reactor program. And 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
59 I can tell you that the vendor swore up and down it 1
was not their fuel that caused the massive failures in 2
those irradiations until they happened at both Idaho 3
and Oak Ridge. And then it was oh, it wasn't those 4
guys doing the irradiation. It was us who made the 5
fuel. And they still couldn't figure out what they 6
did until PIE was performed. And it was subtle. They 7
had made changes and were convinced that it wouldn't 8
make any difference.
9 This is the same argument as saying an 10 accident-tolerant fuel where I'm going to change 11 either the fuel pellet or the cladding in some minor 12 way and I don't have to irradiation test it and yet 13 they are being irradiation tested. I mean that's just 14 sort of like the first commandment of fuel behavior, 15 people.
16 MR. BLEY: Well, this is Dennis Bley.
17 And, Dave, I certainly don't have your expertise in 18 the fuels area, but it's not just the golden rule of 19 fuels. All across technology there are so many cases 20 of places where we designed a new system specifically 21 to solve a problem in an existing one and yet when we 22 put it into service it probably did solve that 23 problem, but new ones were introduced. And the idea 24 that you don't need testing because you haven't 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
60 thought of what's going to go wrong is just not 1
comforting.
2 MR. TOMKINS: Well, it's not that we're 3
not doing testing, because there's been a lot of 4
testing of the particles and there's separate testing 5
of a pebble. But you're right, as an integrated 6
entity we're not doing irradiation testing.
7 CHAIR PETTI: Right. I mean I completely 8
agree with much of the documentation about the 9
positives that the two technologies bring, but when 10 you bring two technologies together, besides bringing 11 the positives, you can potentially bring some 12 negatives. And just thinking in that failure space is 13 what I think Dennis and I are both talking about.
14 MR. TOMKINS: Okay. Next slide. I think 15 the last couple are mine. So I'm just going to click 16 through these. We kind of covered these, but there's 17 50 years of operating and testing experience on these 18 p a r t i c l e s c e r t a i n l y.
19 We did a PERT and we implemented actions to 20 address the PERT. The manufacturing and inspection of 21 the fuel will be to a spec that ensures that it's 22 equivalent to what was tested in AGR-2. We're also 23 going to meet the conditions in the TRISO Topical 24 Report. I think there's five conditions and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
61 limitations in that report, so we will have to make 1
sure that our fuel meets those conditions. We're 2
going to operate well within a defined set of fuel 3
qualification limits during both normal and licensing 4
basis events.
5 Next slide? We will do irradiation 6
testing if the TRISO particle is going to operate 7
outside of AG-2, which might be needed for the 8
commercial reactor. We have a surveillance program 9
that confirms that the pebble form is not adversely 10 impacting fuel particles. We can talk a little bit 11 about this in the closed session, but we're going to 12 take a camera shot of these pebbles that come through.
13 And so if the wear is through and particles are 14 exposed, we would know that. And then we have the 15 ability to examine pebbles as they -- oh, I just 16 mentioned that. And we're also going to do PIE on 17 both the test reactor and on the commercial reactor.
18 Of course that's obviously after the fact.
19 Next slide?
20 CHAIR PETTI: So, Jim, just a question:
21 Are you also planning on potentially taking a pebble 22 out before it reached its full burnup, if you will, 23 and do PIE? So you'd have them at 25 percent, 50 24 percent, and 75 percent?
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62 MR. TOMKINS: Hadn't really thought about 1
that, but you wouldn't get the burnup of course.
2 CHAIR PETTI: Right, but you'd get sort of 3
a characterization, if you will, one-every-so-often-4 sort of thing.
5 MR. TOMKINS: That isn't currently part of 6
our plans, but --
7 CHAIR PETTI: Yes.
8 MR. TOMKINS: So conditions. Joy, did you 9
have a question?
10 MEMBER REMPE: Yes, it's something I 11 forgot to ask earlier. If this is a good time to have 12 a detracting question, on slide 31 on the material 13 compatibility, it has Flibe -- the acceptance criteria 14 is Flibe interaction with the pebble does not result 15 in damage to the fuel region of the pebble. How do 16 you define damage? Does that mean if you see any 17 Flibe ingress into the fueled region? So it goes past 18 the unfueled region into that region, you'll stop and 19 say we got to stop here, folks, we've got a problem?
20 Or does it have -- is there something more significant 21 than ingress? And if it's just ingress or 22 infiltration, then why don't you say Flibe 23 infiltration into the fueled region of the pebble?
24 MR. LATTA: We're looking for -- what 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
63 you're looking for would be like degradation, so 1
microstructural changes that could impact either heat 2
transfer or the mechanics of the pebble and break down 3
from expected -- what we expect of the material. So 4
it would be --
5 MEMBER REMPE: It's going to be a harder 6
thing if you -- I mean one, you ought to be specific 7
and say okay, I want to do testing to see if it 8
adversely affects heat transfer in the fueled 9
region --
10 MR. LATTA: Yes.
11 MEMBER REMPE: -- or material properties.
12 MR. LATTA: Sure.
13 MEMBER REMPE: Or an easier criterion to 14 have is the acceptance criteria is that you don't have 15 Flibe ingress into the fueled region.
16 MR. LATTA: Yes.
17 MEMBER REMPE: I mean, you can do that if 18 you want to, but then okay, how much degradation in 19 the heat transfer? I mean, this is a very vague 20 criterion in my opinion and so I think you ought to be 21 more specific. And the easiest way to deal with that 22 would just say ingress into the pebbled fuel region.
23 MR. LATTA: Yes. Well, then the 24 expectations that really see -- is not to observe 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
64 anything occurring because these materials have been 1
shown to be highly compatible and they're 2
thermodynamically compatible. And there's been a lot 3
of experience in the other tests and in the MSRE to 4
show that graphite is compatible with Flibe. So we're 5
just really kind of trying to confirm that when we use 6
our materials that we see this same history of 7
compatibility between the materials.
8 MEMBER REMPE: So again, I lobby for you 9
ought to just say ingress to confirm what you've seen 10 elsewhere unless you want to try and go further. And 11 if you want to go try --
12 MR. LATTA: Yes.
13 MEMBER REMPE: -- and go further, then 14 please be specific so we know what it is.
15 MR. LATTA: Sure.
16 MR. TOMKINS: Okay. So I'm just going to 17 close with the limitations. So we have some 18 limitations we've put on ourselves. And we also have 19 one that was in the NRC's SER.
20 The first limitation is that this 21 methodology only applies if the design is described in 22 Section 112 and you have Flibe that's maintained.
23 We have to demonstrate that the operating 24 conditions and the safety analysis conditions are 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
65 within the qualification limits that we've specified 1
in table 3-11 of the report.
2 If we're going to extend that envelope, then we 3
have to do an irradiation program. We also have to 4
meet the limitations and conditions in the EPRI TRISO 5
Topical Report, which I previously mentioned that.
6 There's a couple of conditions that we 7
have to meet for the power reactor, and that is we've 8
got to provide additional justification on the 9
applicability of this methodology during rapid 10 transience and additional justification that Flibe 11 does not inversely impact irradiated fuel pebble 12 buoyancy.
13 And then this methodology only applies to 14 a design with a safety-related positive flux rate 15 trip. And then the NRC has added SER limitations to 16 justify the applicability of this methodology to a 17 test reactor for rapid transients. That's it.
18 CHAIR PETTI: Members, questions?
19 Okay. Then I guess who from the staff is 20 going to be presenting?
21 MR. VAN WERT: That will be me. This is 22 Chris Van Wert.
23 CHAIR PETTI: Hi, Chris.
24 MR. VAN WERT: Hey, how are you doing?
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66 CHAIR PETTI: Okay.
1 MR. VAN WERT: So do we jump into it now?
2 I didn't --
3 CHAIR PETTI: Well, I was just going to --
4 I'm sitting -- how many slides do you have?
5 MR. VAN WERT: It is -- one second -- I 6
believe it's about 10 or 11, somewhere around there.
7 CHAIR PETTI: Well, why don't we take a 8
10-minute break then and we'll come back at half past 9
the hour?
10 MR. VAN WERT: Sounds good.
11 CHAIR PETTI: Thanks.
12 MR. VAN WERT: Thank you. So, okay, 3:30 13 your time? Okay.
14 MEMBER REMPE: And the slides from the 15 staff are now open slides, is that true? They were 16 given to us --
17 MR. VAN WERT: Correct.
18 MEMBER REMPE: Okay. Thank you.
19 MR. VAN WERT: And I will share/control 20 them, so --
21 (Whereupon, the above-entitled matter went 22 off the record at 3:20 p.m. and resumed at 3:30 p.m.)
23 CHAIR PETTI: Okay. We're back in.
24 Chris, it's yours.
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67 MR. VAN WERT: All right. I'm going to go 1
ahead and share the slides, so give me one second.
2 (Pause.)
3 MR. VAN WERT: All right. Is that visible 4
to everyone okay?
5 CHAIR PETTI: Yes, looks good.
6 MR. VAN WERT: So I will also say before 7
we start here that I will not be able to see -- while 8
sharing it I can't see the rest of the screen from the 9
Teams meeting, so I am asking the other NRC members to 10 keep an eye out for any raised hands and to speak up 11 and let me know if there's a question. Also any of 12 the members, please feel free to just speak up during 13 the presentation as well, but we will continue on that 14 then. And like I said, feel free to speak up at any 15 time.
16 All right. Are we ready to start then?
17 CHAIR PETTI: Yes, go ahead.
18 MR. VAN WERT: Okay. So good afternoon, 19 everyone. My name is Chris Van Wert and I'm a senior 20 reactor systems engineer in Technical Branch 1 of the 21 Division of Advanced Reactors, Non-Power Production 22 and Utilization Facilities. I will be presenting the 23 staff's review of Kairos' topical report, Fuel 24 Qualification Methodology for the Kairos Power 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
68 Fluoride Salt-Cooled High Temperature
- Reactor, 1
Revision 2.
2 So Kairos requested the staff's review and 3
approval of the topical report which provides the 4
methodology for qualifying the Kairos fuel pebble 5
design for either a power or non-power version of the 6
KP-FHR. The staff's review is focused on the overall 7
fuel qualification of the framework fuel 8
qualification framework which includes but not limited 9
to the use of existing data, unirradiated testing, 10 irradiation
- testing, and surveillance.
11 It's important to note that the topical 12 report is applicable to both non-power tests and power 13 versions of the KP-FHR, as we've mentioned already, 14 and the staff considered this in the review.
15 Also, this topical report does not 16 directly present any fuel performance code updates for 17 staff review and approval, but is instead focused on 18 the methodology itself to support fuel qualification.
19 That being said, the data obtained from the fuel 20 qualification process can be used in future 21 performance code updates, but that is not covered 22 directly as part of this topical report or the staff's 23 review.
24 Just quickly, the regulatory basis for the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
69 fuel qualification framework is -- includes 10 CFR 1
50.34(a) and (b),
and the 2
corresponding regulations for design certifications, 3
COLs, and standard design approvals in 10 CFR Part 52.
4 The licensing basis also includes 10 CFR 100.11.
5 Additionally Kairos Power's PDC 10 and PDC 16, which 6
were previously approved by the staff in Topical 7
Report KP-TR-003MP-A, are also part of the licensing 8
basis.
9 So the first discussion topic I wanted to 10 cover you just heard about in Kairos' presentation, 11 but this is the applicability of the existing data.
12 And the Kairos Power fuel qualification methodology 13 builds upon the approved topical report on TRISO fuel 14 particle qualification, EPRI-AR (NP)-1. This was a 15 topical report submitted by EPRI in coordination with 16 INL to provide TRISO particle testing data and 17 qualification from the AGR-1 and 2 campaign.
18 This topical report serves as a fuel 19 qualification for TRISO fuel particles as long as it's 20 within the fuel specifications and operational 21 conditions defined by the AGR-1 and 2 Program.
22 Additional existing data related to carbon 23 matrix property data was used to inform Kairos' 24 testing plans to support fuel qualification.
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
70 The staff reviewed the Kairos fuel 1
particle specifications in comparison with the AGR-1/2 2
campaign and finds that the Kairos particle 3
specifications are consistent with the AGR-2 TRISO 4
test particles and therefore the data is applicable to 5
the Kairos particle design up to the test conditions 6
investigated as part of AGR-2.
7 Additionally the staff finds that the carbon 8
matrix property data is acceptable for informing the 9
test conditions as used in the topical report.
10 In Section 3.6 of the topical report 11 Kairos presents their planned fuel pebble laboratory 12 testing and it will be used to obtain Kairos' fuel 13 pebble data in support of fuel qualification. And 14 this includes mechanical tribology, buoyancy and salt 15 infiltration, material compatibility.
16 The staff reviewed the pebble test to 17 confirm that the testing conditions chosen would bound 18 those experienced by the fuel pebbles in reactor 19 conditions and that the testing methods either 20 followed an established method or were appropriate for 21 obtaining the desired data. The staff found the fuel 22 pebble testing as presented in Section 3.6 of the 23 topical to be acceptable for determining Kairos' fuel 24 pebble characteristics to support fuel qualification.
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
71 Section 3.7 of the topical report 1
addresses planned irradiation testing to support 2
operation of TRISO particles outside of the AGR-2 3
operational envelope if desired. I said a little bit 4
about that earlier that there's a certain box that the 5
AGR program kind of gave them an area to start with.
6 And Hermes fits within that, however the desired power 7
reactor version goes beyond that. So the irradiation 8
testing does include fuel pebble irradiation in a gas 9
environment, purged gas monitoring for fission gas, 10 and post-irradiation examinations.
11 The staff reviewed the description of the 12 irradiation test plans as presented in Section 3.7 and 13 notes that similar to the EPRI-AR (NP)-1 TRISO 14 particle fuel qualification topical report the 15 methodology uses sweep gas monitoring to initially 16 determine the release rate to birth rate ratio of 17 gaseous fission product releases from the test levels, 18 which is then followed by PIE. The non-destructive 19 PIEs include visual examinations, dimensional 20 measurements and gamma-spectroscopy to identify gross 21 external damage and burnup as well.
22 The Kairos power fuel qualification 23 methodology also includes destructive PIEs of a 24 limited number of test pebbles. This destructive 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
72 examination includes using the DLBL technique to 1
quantify fuel particle failure fraction. These DLBL 2
results can't results can't be used -- can be used to 3
confirm the failure fraction calculated by measuring 4
fission gas release during the irradiation test.
5 Staff finds that the irradiation testing 6
presented in Section 3.7 is closely related to the 7
previously approved topical report EPRI-AR (NP)-1 and 8
is acceptable for determining irradiated fuel failed 9
particle fraction and gross double behavior which 10 could impact behaviors of operation outside the bounds 11 of the AGR-2 test conditions.
12 Section 3.8 of the topical report 13 addresses fuel particle performance modeling and 14 discusses how the data collected from the fuel 15 qualification program will be used to inform and 16 improve fuel performance models. The staff's approval 17 of this topical report is related to the fuel 18 qualification methodology by which Kairos' fuel pebble 19 can be qualified. The staff further finds the data 20 collected while implementing the fuel qualification 21 methodology is acceptable for use in updating the 22 Kairos fuel performance model KP-BISON, however the 23 staff's approval of the fuel qualification topical 24 report does not approve a priori any modifications to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
73 the fuel performance model itself beyond whatever is 1
allowed by the staff's approval of the KP-BISON.
2 Section 3.9 of the topical report 3
addresses fuel surveillance plans for the initial test 4
and power KP-FHR cores which are used to both monitor 5
fuel performance and to collect data for fuel 6
performance codes. The fuel surveillance plan 7
includes cover gas monitoring, non-destructive 8
examinations, and destructive examinations.
9 Again the staff reviewed the surveillance 10 plans as presented in Section 3.9 and finds that, one, 11 the use of cover gas monitoring is an acceptable means 12 for measuring in real time any unexpected gross 13 failures of particles which could lead to an increase 14 in fission gas inventory in the cover gas.
15
- Two, the non-destructive visual 16 examination methods are acceptable for determining if 17 a pebble has wear or other damage sufficient enough to 18 potentially impact the TRISO particles.
19 Three, the use of gamma-spectroscopy --
20 spectrometry is acceptable for determining burnup 21 levels to determine if the pebbles can be reinserted 22 into the core or should be instead sent to storage.
23 Four, the DLBL destructive examinations 24 are acceptable for confirming the failed fuel particle 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
74 fraction as seen in the sweep gas measurements.
1 And five, the destructive examinations are 2
also acceptable for confirming the wear and Flibe 3
infiltration separate effects test results.
4 Staff limitations. In addition to the 5
fuel qualification methodology limitations provided --
6 oh, yes?
7 Sorry. I thought I heard someone.
8 So in addition to the limitations that 9
were presented by Kairos within their topical report 10 the staff has the following limitation as well: And 11 that's that future license applications for non-power 12 KP-FHRs will include justification for the 13 applicability of this methodology during rapid reactor 14 transient events.
15 This limitation was intended to cover a 16 gap in that the topical report only directly addresses 17 rapid reactor transient events for power reactors in 18 the Kairos limitations. And this is because the 19 Hermes application addresses this issue directly in 20 its PSAR, so this limitation was not perceived 21 initially as being necessary in this topical report.
22 However, the staff decided to include this limitation 23 in its approval since the topical report addresses 24 non-power test reactors in general and not just 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
75 Hermes. The staff limitation on the approval 1
therefore covers all of any potential non-power KP-2 FHRs.
3 CHAIR PETTI: So, Chris --
4 MR. VAN WERT: Yes?
5 CHAIR PETTI: -- let me just understand.
6 You're basically saying that the qualification doesn't 7
include reactivity testing? Is that correct?
8 MR. VAN WERT: Correct.
9 CHAIR PETTI: Okay. But I thought the 10 licensee went through some very good discussions about 11 the response of their system to reactivity events.
12 You guys just didn't accept it because it wasn't 13 validated, or you just didn't accept it -- I'm trying 14 to understand how you got here.
15 MR. VAN WERT: So the -- you'll hear about 16 it more later. The Hermes application actually had 17 even more information, and the staff's review of that 18 is going to be included there.
19 CHAIR PETTI: Ah.
20 MR. VAN WERT: So we were trying to figure 21 out where to put it. We could either have asked for 22 additional information to be put into the topical 23 report and address it here or just leave it there and 24 put the staff's review and approval within that SER 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
76 for the PSAR application.
1 CHAIR PETTI: Okay.
2 MR. VAN WERT: So you will hear about it 3
later.
4 CHAIR PETTI: Okay. I see Jeff Schmidt 5
has his hand up.
6 MR. VAN WERT: Okay.
7 MR. SCHMIDT: Yes, Dr. Petti, I was just 8
going to help Chris out here.
9 So I wrote the PSAR section for Hermes for 10 the fuel and I thought it was just better to use the 11 specific data for Hermes to address the lack of 12 transient testing. So that's why it rolled from this 13 topical report into the PSAR.
14 CHAIR PETTI: Okay. Thanks.
15 MEMBER REMPE: So this is Joy and I had a 16 question or two.
17 MR. VAN WERT: Yes?
18 MEMBER REMPE: It's tracking things. For 19 example, my question earlier about well, gee, KP-BISON 20 hasn't been validated and there's data required for 21 it. And I assume the staff is tracking all this very 22 carefully, because again their presumption that it's 23 okay to do this for the now-power application is based 24 upon KP-BISON calculations.
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77 Likewise, I'm curious about if your 1
approval has considered things like buoyancy tests 2
only go to 900 C, but the power reactor is supposed to 3
have a normal -- it's like 1,100 C for operating. And 4
so are you tracking and saying okay, they can use it 5
for Hermes, but not the other reactor until they do 6
higher temperature testing? Is there some place where 7
the staff has all this documented carefully?
8 MR. VAN WERT: So I'll try to address it 9
all; please let me know which parts I miss and I'll go 10 back to it.
11 So yes, the initial -- and Jeff was the 12 lead reviewer for the KP-BISON topical report, and he 13 can jump in as well I'm sure. But the initial topical 14 report in this review is associated on its -- on the 15 data supplied by the AGR-2 Program. And within those 16 bounds -- yes, Hermes is going to operate within 17 those.
18 When you're talking about updating KP-19 BISON in the future as we're getting this data, that's 20 for when we're looking at operations outside of the 21 AGR-2 Program. So I wanted to make sure that that was 22 clear.
23 Joy, was there --
24 MEMBER REMPE: So let me stop you real 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
78 quick here.
1 MR. VAN WERT: Yes, yes.
2 MEMBER REMPE: So you're telling me you 3
have confidence even though KP-BISON hasn't been fully 4
validated, it has been validated using the data from 5
AGR testing -- that you feel comfortable that all of 6
their assumptions are correct about the operating 7
conditions for Hermes and there's nothing that needs 8
more data?
9 MR. VAN WERT: So I am going to kick that 10 one over to Jeff --
11 MR. SCHMIDT: Yes.
12 MR. VAN WERT: -- since he's the author 13 for KP-BISON's --
14 MR. SCHMIDT: Dr. Rempe, so for -- some of 15 this stuff I think we can talk about in the closed 16 session. The short answer is yes for Hermes. We 17 looked at the operating conditions and the test ranges 18 and it's fine for Hermes. I don't know if I looked 19 personally at the commercial design. I might have to 20 go back and take a look at that, but for the Hermes it 21 is.
22 MEMBER REMPE: Okay. Because I mean they 23 don't have material compatibility testing done yet for 24 Flibe and the fuel, and I would have thought that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
79 would be something that would be important for KP-1 BISON. And I thought there was a lot of other testing 2
where they acknowledged they used some data that had 3
been collected in the literature, but they wanted 4
additional data. And I would have to go back and look 5
at what all needed to be obtained, but I thought 6
basically they were missing some just fundamental 7
properties of materials.
8 MR. SCHMIDT: Yes.
9 MEMBER REMPE: And I'm a little surprised 10 that they are --
11 MR. SCHMIDT: So let me clarify my 12 statement, I guess. The ranges of data, ranges of 13 like temperatures I was responding to, there has been 14 on V&V of the BISON code.
15 MEMBER REMPE: Okay. So that will have to 16 be --
17 MR. SCHMIDT: That's all I really need to 18 say about that.
19 MEMBER REMPE: That will have to be done 20 before one can have confidence that they don't need to 21 have additional irradiation testing for Hermes, right?
22 MR. SCHMIDT: Yes, that is correct. For 23 an operating license for Hermes our expectation is 24 that those will be -- the codes will be V&V'ed. All 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
80 the codes that --
1 MEMBER REMPE: They might --
2 MR. SCHMIDT: -- are necessary for Hermes.
3 MEMBER REMPE: They may have a surprise 4
then. They'll build the reactor, get a construction 5
permit. And then they may have a surprise because the 6
NRC could say oh, well, you know, it's not validated 7
and you need to get some more data here. And that 8
could happen. Just so everybody understands that 9
because it wasn't clear to me from the SE and from the 10 initial responses today.
11 And then when you go to the up-rated 12 electric power KP-FHR, somebody needs to do a careful 13 look at this SC, because again they only did testing 14 for buoyancy up to 900 C. And I was curious why they 15 didn't go on up to 1,100 C, but I thought well, okay, 16 if that's all you need to do for Hermes, okay, but the 17 staff SE should maybe make a note somehow or other 18 that they did not -- that that SE is only valid for 19 Hermes because higher temperatures or other types --
20 I didn't go through and look at all of the conditions, 21 but they didn't do -- they're not planning or 22 proposing to do testing for the full electric power 23 KP-FHR.
24 MR. VAN WERT: To be clear, what 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
81 temperature are you referring to? If you're talking 1
about --
2 (Simultaneous speaking.)
3 MEMBER REMPE: -- testing. If I look at 4
the anticipated electric power conditions, it's less 5
than 1,100 C. And then if I go to the laboratory 6
testing on slide 29, test temperatures up to 900 C and 7
pressure up to 500 KP for buoyancy testing. So either 8
they need to bump up their test temperature a little 9
bit when they do it the first time or it's not going 10 to be valid for the electric power.
11 MR. VAN WERT: So I don't want to say the 12 specific number, because it's listed as proprietary, 13 but --
14 MEMBER REMPE: I'm looking at their open 15 slides, by the way. I'm not looking at anything --
16 MR. VAN WERT: Oh, okay. Okay. Sorry.
17 I was looking at --
18 (Simultaneous speaking.)
19 MR. VAN WERT: Okay. So I was looking at 20 table 3-17 from the topical report. And if you're 21 talking about the pebble surface temperature, I don't 22 think we're looking at the same number then.
23 MEMBER REMPE: Okay. So I'm looking at 24 anticipated conditions, which again it is the peak 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
82 silicon carbide. I don't have a surface temperature.
1 So you're saying the surface temperature will be 2
covered by the 900 C? Okay. That helps me then.
3 Have you looked carefully --
4 MR. VAN WERT: And once we get --
5 MEMBER REMPE: -- at all of the --
6 MR. VAN WERT: Once we get to -- yes, 7
we'll tell you numbers in closed.
8 MEMBER REMPE: Okay.
9 MR. VAN WERT: And I think I have a backup 10 slide with that table if we would like to see it, 11 but --
12 MEMBER REMPE: But for the open session 13 you've carefully looked at their test conditions and 14 it covers not only Hermes but also the electric power 15 design?
16 MR. VAN WERT: Well, you mean specific to 17 the buoyancy?
18 MEMBER REMPE: Well, all of the testing.
19 There's a lot of other testing that they --
20 MR. VAN WERT: Okay.
21 MEMBER REMPE: -- have too.
22 MR. VAN WERT: So yes. No, the answer to 23 that would be the equilibrium core conditions go above 24 and beyond the AGR-2 Program. And so some of the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
83 irradiation tests are not bounded by the available --
1 (Simultaneous speaking.)
2 MEMBER REMPE: Right.
3 MR. VAN WERT: And that's why that was 4
addressed -- I think it's in Section 3.7.
5 MEMBER REMPE: Right. Other than the 6
irradiation tests --
7 MR. VAN WERT: Correct.
8 MEMBER REMPE: -- the laboratory tests is 9
where I have --
10 MR. VAN WERT: Yes, the laboratory tests 11
-- yes.
12 MEMBER REMPE: And you guys are tracking 13 what is and isn't covered for each design was the 14 underlying question here.
15 MR. VAN WERT: Correct. Correct.
16 MEMBER REMPE: Okay. Thank you.
17 MR. VAN WERT: Yes, thanks.
18 CHAIR PETTI: Jeff has his hand up, Chris.
19 MR. VAN WERT: Okay. Hey, go ahead, Jeff.
20 MR. SCHMIDT: Yes, I was just going to say 21 there's other material limits, Dr. Rempe, that would 22 stop you from going above 900 C. And we can probably 23 discuss those more in the closed session.
24 MEMBER REMPE: Thank you.
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84 MR. TOMKINS: Could I just add one point 1
following that discussion? And that is that the --
2 you were talking about validation of KP-BISON. So 3
Kairos is working on that right now. So I'm not 4
saying it's done yet, but we're -- that's something 5
we're actively working on.
6 MEMBER REMPE: Good. But I hope you have 7
data to finish it, because that was my impression when 8
I was looking at the SE is that yes, okay, it sounds 9
like a good idea, but until you have data -- and, you 10 know? So anyway.
11 MR. TOMKINS: Yes. Okay.
12 MR. VAN WERT: So were there any more 13 questions or --
14 CHAIR PETTI: Chris, I want to throw the 15 question I threw to Kairos to you guys: Why didn't 16 you require an irradiation given the Chinese even 17 proof irradiation test. I mean I just can't 18 understand. Is it because it's a test reactor that 19 somehow it has a lighter touch?
20 MR. VAN WERT: We kind of -- we had to 21 look at it holistically. So we were looking at the 22 literature data that was presented. We were looking 23 at the gas environment irradiation tests that they do 24 plan to do. And then also recognizing that they have 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
85 a surveillance plan. So at the end of -- well, at the 1
end of both, Hermes as well as the power reactor, but 2
in this case of interest it's the end of Hermes they 3
will be doing all sorts of examinations including the 4
non-destructive and destructive PIE. And so that data 5
will become available.
6 And then also their ability to look at the 7
cover gas products as they accumulate allows them to 8
kind of keep on top of it. So if you look at it 9
holistically in its entirety, we felt that the 10 reasonable assurance threshold was crossed and we felt 11 it was a good foundation.
12 I am not opposed if they so desire to do 13 additional tests, but we had to make that safety 14 determination and that was where we came from.
15 CHAIR PETTI: So the key issue is that 16 yes, the gas will tell you if you failed all the 17 TRISO, but if you feel the silicon carbide, it's a lot 18 harder to do that for monitoring. That's why I was 19 intrigued initially when I read about the salt. I'm 20 just not sure if it will have the sensitivity. I'd be 21 interested to see what a computer model would say 22 there.
23 But in the old days when the South African 24 pebble bed came in, the folks sitting in your seats 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
86 were basically telling them they had to take pebbles 1
out periodically and look at them and examine them 2
sort of as a fuel surveillance -- as part of the fuel 3
surveillance program.
4 MR. VAN WERT: Yes, and at the operational 5
plans for Hermes, I don't think it gets -- it doesn't 6
stress it enough until you're towards the end of its 7
life. So I think the surveillance plan, the test data 8
that you collect at the end of it is going to be more 9
telling and more -- of the full power operation later.
10 If we took it out at 25 percent power, unless there 11 was a -- like you were alluding to earlier, a 12 manufacturing defect that would be gross over the vast 13 majority of pebbles and particles, I think that's the 14 only case where you would potentially see something.
15 And we couldn't find a way of thinking of that 16 happening.
17 Yes, we can discuss more I suppose in the 18 closed session all together, but that -- I just wanted 19 to give you at least that overview of the approach we 20 took as far as looking at all the different 21 components. And adding it together in aggregate we 22 thought was a strong safety case.
23 CHAIR PETTI: I see Jeff's hand's up.
24 Jeff?
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87 MR. SCHMIDT: Yes, I just wanted to chime 1
in, too. I think you asked a good question there.
2 For me it was the destructive testing for the initial 3
non-power test reactor personally as a reviewer. That 4
was important to me to add to be able to use the test 5
reactor to get data in a real-life FHR, right? The 6
data that you might be referring to would still be say 7
in a gas environment.
8 CHAIR PETTI: Yes.
9 MR. SCHMIDT: This getting data from a 10 prototypical reactor is probably the most informative 11 you could do, or you could get. So we, at least I 12 thought that was the key in proceeding forward.
13 CHAIR PETTI: Yes. No, I would not 14 recommend that they have to test it in salt. That's 15 not an easy thing to do in a test reactor. Very 16 difficult to prevent the salt from freezing all the 17 time. If you have an unexpected scram in your test 18 reactor, which happens, it's much more challenging to 19 do a salt -- flowing salt experiment in the test 20 reactor.
21 MR. SCHMIDT: So it does kind of -- I 22 think from the staff's perspective it does kind of 23 leverage the test reactor aspect.
24 CHAIR PETTI: Yes, it just doesn't come 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
88 through enough I guess in either the topical report or 1
the SE that -- it comes across as sort of after the 2
fact. It doesn't come through enough to me at least.
3 Okay.
4 MR. SCHMIDT: Yes, there was significant 5
-- all I can tell you is there was very significant 6
dialog between us and Kairos regarding that item.
7 CHAIR PETTI: Yes. Okay.
8 MEMBER REMPE: In that dialog did you ask 9
them how much fluence they intend to accumulate with 10 Hermes? I mean, I know they're going to shut it down 11 like in four years, right? And when we asked, they 12 didn't really have any sort of specification for 13 capacity factor. So do you need to have any sort of 14 fluence -- total operating history you want to see?
15 MR. SCHMIDT: Yes, I mean, it's bounded by 16 the fluence by the AGR-2 Program from a particle 17 standpoint, if that's what you're referring to, the --
18 (Simultaneous speaking.)
19 MEMBER REMPE: I'm talking about Hermes.
20 How much -- have you --
21 (Simultaneous speaking.)
22 MR. SCHMIDT: You mean like from a vessel 23 fluence?
24 (Simultaneous speaking.)
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89 MEMBER REMPE: -- up to power or do you 1
want it at full power after so many days?
2 MR. SCHMIDT: No, I mean we're not 3
specifying. I think the assumption in Hermes is that 4
it's 100 percent capacity factor, which is probably 5
unrealistic --
6 (Simultaneous speaking.)
7 MEMBER REMPE: Well, I don't think they've 8
ever said that, because we asked them. Maybe they can 9
speak up, but I know we asked them that when we had 10 the overview introduction. I mean, it's only going to 11 run for four years. And I asked about the capacity 12 factor, and they said they hadn't come up with that.
13 Are you guys trying to do 100 percent 14 capacity factor?
15 PARTICIPANT: That's in closed section.
16 PARTICIPANT: We moved that to the closed 17 session also.
18 MEMBER REMPE: Sure.
19 CHAIR PETTI: Sure. So let me ask a 20 different question, Chris. They've committed to doing 21 an irradiation test in the topical for the power 22 reactor, but if things go swimmingly well in Hermes 23 and they're going -- like if they could come up with 24 a way to do it in Hermes, would that be allowed? I 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
90 mean, they'd obviously have to file more paperwork, 1
but they'd go beyond AGR-2, but they'd use Hermes 2
instead of a test reactor. Would that be something 3
that is at least not off the table?
4 MR. VAN WERT: So I mean if they could run 5
Hermes such that they could get that data, that would 6
be in my opinion fine. I would support having that 7
data ahead of time. But our understanding of the 8
power levels, the fluence, the burnups, et cetera, 9
that they can achieve within Hermes -- and keep in 10 mind it's also with a time frame. They could achieve 11 higher burnup by operating it longer of course, but at 12 some point at the power levels that Hermes will 13 operate at they're going to run out of time before 14 they want to build the full-power version of KP-FHR.
15 So we're not opposed to it. I just don't 16 think that Hermes will get them to those levels beyond 17 AGR-2 within the time frame that they'll need. So 18 that's why I think they're ending up in this space 19 where they're using a non-power -- sorry, a non-Hermes 20 test facility --
21 CHAIR PETTI: Sure. Yes.
22 MR. VAN WERT: -- to get those levels.
23 CHAIR PETTI: Okay. Thanks.
24 Other members, questions?
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
91 Okay. Well, let's open the line for 1
public comment before we go into our closed session 2
then.
3 Any members of the public, un-mute 4
yourself, state your name and your comment for the 5
record.
6 Hearing none, I guess we're concluding the 7
open session and we will get onto the closed session 8
for other comments from members.
9 And, Jim, you'll scan the list to make 10 sure everybody on your side is supposed to be there?
11 And I suppose Chris and Jeff will do the same on the 12 NRC side.
13 MR. TOMKINS: Yes, could I ask for anybody 14 from the Kairos team, if you're going to call in by 15 phone, let -- send me an email saying that. Does 16 anybody plan to call in by phone or is everybody going 17 to use the Teams link?
18 Okay. I didn't hear anybody saying 19 they're going to call in by phone. So I think we 20 should be okay because we should -- they'll have the 21 link.
22 MEMBER BALLINGER: Dave, this is Ron. We 23 have a separate invitation. Are we just going to stay 24 here?
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
92 CHAIR PETTI: No, no. We're going to go 1
over to the separate -- we got to switch over to the 2
separate invitation.
3 MEMBER BALLINGER: I got it. Okay.
4 MR. TOMKINS: So and again, everybody from 5
Kairos, open up the closed file.
6 And so, Dave, what, are we going to go 7
there right now? Do you want to --
8 CHAIR PETTI: Yes.
9 MR. TOMKINS: -- take a short break?
10 MEMBER BROWN: Hold on. Dave, Dave, Dave?
11 CHAIR PETTI: Yes, Charlie?
12 MEMBER BROWN: This is Charlie. Yes, did 13 we get the closed session slides? I had looked for 14 those and couldn't find them.
15 PARTICIPANT: There aren't any.
16 MR. WANG: I will send to you. It should 17 be on your calendar. You're Charlie, right?
18 MEMBER BROWN: I got two sets of slides.
19 They were both open.
20 CHAIR PETTI: Yes, there's no closed 21 slides, Charlie. It's just for some Q & A.
22 MEMBER BROWN: Okay. That's all I wanted 23 to know. Thank you.
24 CHAIR PETTI: Okay. So we're going to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
93 terminate this one and see everybody in the closed 1
session.
2 MR. WANG: And I will admit Jim. And 3
then, Jim, then you help me to look at your need to 4
know people. Okay. Thank you.
5 MR. TOMKINS: Will do. Thank you.
6 CHAIR PETTI: Thank you.
7 (Whereupon, the above-entitled matter went 8
off the record at 4:04 p.m.)
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
KAIROS POWER ACRS KAIROS POWER SUBCOMMITTEE MEETING OCTOBER 17, 2022 OPEN SESSION KP-FHR Fuel Qualification Methodology Topical Report Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
- 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
Introduction 2
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
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 Fuel Qualification 3
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
4
KP-FHR Overview Parameter Description / Value Reactor Name Hermes KP-X Reactor Type Non-Power Test Reactor Commercial Electric 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 /
Electric Power 35 MWth / N/A 320 MWth / 140 MWe Reactor Operating Pressure
<0.2 MPa
<0.2 MPa Reactor Inlet /
Outlet Temperature 550°C / 620°C 550°C / 650°C Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
5
6 Annular Fuel Pebble and TRISO Particle Design 6
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
40mm diameter
<1mm diameter
7 Particle Design 7
Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel System Component Purpose UCO Kernel UO2 + UC + UC2 The kernel contains the fissile material.
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 SiC deposition in the manufacturing process.
8 Particle Design (continued) 8 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
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.
9 Pebble Design (continued) 9 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Fuel System Component Purpose Low-density Carbon Core Reduces the pebble density ensuring pebble has net positive buoyancy in the Flibe coolant.
Fuel Region The fuel region is a shell of carbon matrix material surrounding the porous carbon inner core.
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.
Fuel Qualification Methodology Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
10
11 Fuel Qualification Methodology 11 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
- 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
12 Fuel Qualification Methodology (continued) 12 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
- 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
U.S. and International Experience Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
13
National Program Average Particle Power (mW)
Peak Temperature
(°C)
Peak Burnup
(%FIMA)
Peak Fluence (x1025n/m2, E>0.1MeV)
German 100 - 250 800 - 1320 6.7 - 15.6 0.2 - 8.5 Chinese 150 - 250 1017 - 1067 9 - 11 3.8 - 4.9 Japanese 550 1156 6.7 2.8 U.S. Legacy 100 - 400 915 - 1350 12 - 80 2.1 - 11.5 U.S. AGR 55 - 140 800 - 1500 13.2 - 19.6 3.5 - 8.1 14 Summary of U.S. and International Experience 14 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
- 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 1988) led to extensive testing and real time irradiation in the AVR of full commercial scale production fuel
- China and Japan have successfully developed TRISO fuel production and irradiated fuel in prototype and commercial reactors of the prismatic and pebble bed type
- In the US, General Atomics operated prototype and demonstration gas reactors using uranium/thorium carbide based coated fuel particles in prismatic cores
- The AGR program was built on this extensive experience to qualify a UCO TRISO coated fuel particle, Kairos Power leverages this DOE program
15 DOE AGR and German Irradiation Test Data 15 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Test Time (EFPD)
Peak Particle Power (mW)
Ave. Particle Power (mW)
Peak Burnup Compact (%FIMA)
Time-Ave. Peak Temp. Compact
(°C)
Peak Fluence Compact (x1021 n/cm2, 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 Test Number of Compacts Number of Particles SiC Failures TRISO Failures Number of Failures 95%
Confidence Number of Failures 95%
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 which has historically been considered the standard for TRISO fuel performance.
16 DOE AGR and German Furnace Safety Test Data 16 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Test Temperature
(°C)
Number of Compacts Number of Particles SiC Failures TRISO Failures Number of Failures 95%
Confidence Number of Failures 95%
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 up to 1600°C and above.
Kairos Fuel Pebble and Particle PIRT Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
17
18 Fuel Particle and Pebble PIRT 18 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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- 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
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 Fuel Particle and Pebble PIRT 19 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
20
- 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 Fuel Specification, Manufacturing, and Quality Control 21 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Source Material or Fabricated Component Measured Characteristic in Inspection Program 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 graphite Density, grain size, surface area, impurities, boron equivalent 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 Fuel Specification, Manufacturing, and Quality Control 22 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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Fuel Qualification Envelope Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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23
- 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 Fuel Operating Envelope 24 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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25 Fuel Operating Envelope and Qualification Limits 25 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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Parameter Proposed Qualification Envelope Anticipated Non-Power Test KP-FHR Conditions Anticipated Commercial Electric Power KP-FHR Conditions Normal Operation Peak SiC Layer Temperature (°C) 1360
< 900
< 1100 Burnup (%FIMA) 13.2
< 10
< 20 Peak Particle Power (mW) 155
< 155
< 350 Peak Fluence (x1025n/m2, E>0.1MeV) 3.8
< 2.0
< 4.0 Postulated Events Peak SiC Layer Temperature(°C) 1600
< 1200
< 1200 Peak Kernel Temperature (°C) 2350
< 1500
< 1500
Fuel Pebble Laboratory Testing Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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26
- Fuel Pebble Laboratory Test Program will demonstrate that annular fuel pebbles meet functional requirements
- Mechanical Tests
- Tribology
- Buoyancy and Molten Salt Infiltration
- Material Compatibility Laboratory Test Program 27 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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Mechanical Tests and Tribology 28
- 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.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Buoyancy, Molten Salt Infiltration (MSI) Tests and Material Compatibility 29
- 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.
Laboratory Test Program Measured Parameter Acceptance Criteria 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 Laboratory Test Program Acceptance Criteria 30 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Laboratory Program Test Measured Parameter Acceptance Criteria Buoyancy Density (mass and volume),
coefficient of thermal expansion Measurements of pebble density and Flibe density made 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 matrix in Flibe Flibe interaction with the pebble does not result in damage to the fuel region of the pebble.
Material Compatibility Corrosion rate of pebble carbon matrix in air Air material compatibility tests analyzed over the lifetime of a pebble does not result in damage to the fuel region of the pebble.
31 Laboratory Test Program Acceptance Criteria (continued) 31 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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Fuel Irradiation Testing Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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32
- 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 Irradiation Testing 33 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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Fuel Performance Model Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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34
- KP-BISON used to analyze response of the fuel during normal operation and transients
- Fuel Pebble DEM modeling
- Fuel Pebble Finite Element Modeling 35 Fuel Performance 35 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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Fuel Surveillance Program Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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36
Fuel Surveillance Program 37
- 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.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
- 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 Summary 38 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
- 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 Summary (continued) 39 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
- 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 Limitations 40 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
No Reproduction or Distribution Without Express Written Permission of Kairos Power LLC.
Questions?
41 End of Presentation 41 Copyright © 2022 Kairos Power LLC. All Rights Reserved.
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 2
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
Regulatory Basis 3
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)
Applicability of Existing Data 4
- 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.
Laboratory Pebble Testing 5
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.
Irradiation Testing 6
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.
Fuel Performance Modeling 7
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
Fuel Surveillance 8
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.
Staff Limitations 9
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.
10 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.
11 Questions?