ML23248A272
| ML23248A272 | |
| Person / Time | |
|---|---|
| Issue date: | 08/23/2023 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| NRC-2510 | |
| Download: ML23248A272 (1) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safegaurds TerraPower NATRIUM Design Reactor Docket Number: (n/a)
Location: teleconference Date: Wednesday, August 23, 2023 Work Order No.: NRC-2510 Pages 1-141 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1716 14th Street, N.W.
Washington, D.C. 20009 (202) 234-4433
1 1
2 3
4 DISCLAIMER 5
6 7 UNITED STATES NUCLEAR REGULATORY COMMISSIONS 8 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 9
10 11 The contents of this transcript of the 12 proceeding of the United States Nuclear Regulatory 13 Commission Advisory Committee on Reactor Safeguards, 14 as reported herein, is a record of the discussions 15 recorded at the meeting.
16 17 This transcript has not been reviewed, 18 corrected, and edited, and it may contain 19 inaccuracies.
20 21 22 23 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com
1 1 UNITED STATES OF AMERICA 2 NUCLEAR REGULATORY COMMISSION 3 + + + + +
4 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 5 (ACRS) 6 + + + + +
7 DESIGN CENTERED LICENSING: TERRAPOWER SUBCOMMITTEE 8 + + + + +
9 WEDNESDAY 10 AUGUST 23, 2023 11 + + + + +
12 The Subcommittee met via hybrid in-person 13 and Video Teleconference, at 8:30 a.m. EDT, Thomas 14 Roberts, Chairman, presiding.
15 16 COMMITTEE MEMBERS:
17 THOMAS ROBERTS, Chair 18 RONALD G. BALLINGER, Member 19 CHARLES H. BROWN, JR., Member 20 VICKI BIER, Member 21 VESNA DIMITRIJEVIC, Member 22 GREGORY HALNON, Member 23 WALT KIRCHNER, Member 24 JOSE MARCH-LEUBA, Member 25 ROBERT MARTIN, Member NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
2 1 DAVID PETTI, Member 2 JOY L. REMPE, Member 3
4 ACRS CONSULTANT:
5 DENNIS BLEY 6 STEVE SCHULTZ 7
8 DESIGNATED FEDERAL OFFICIAL:
9 KENT HOWARD 10 11 ALSO PRESENT:
12 REED ANZALONE, NRR 13 BRIAN JOHNSON, TerraPower 14 NICK KELLENBERGER, TerraPower 15 ED LYMAN, Public Participant 16 CANDACE DE MESSIERES, NRR 17 SCOTT MOORE, ACRS 18 GEORGE PICCARD, TerraPower 19 JESSE SEYMOUR, NRR 20 MALLECIA SUTTON, NRR 21 ERIC WILLIAMS, TerraPower 22 GEORGE WILSON, TerraPower 23 EMILY YOUNG, TerraPower 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
3 1 C-O-N-T-E-N-T-S 2
3 Opening Remarks and Objectives 4 By Thomas Roberts . . . . . . . . . . . . . 4 5 TerraPower Nuclear Island and Energy Island 6 Interface TR Submittal 7 By Nick Kellenberger, Eric Williams, George 8 Wilson . . . . . . . . . . . . . . . . . . 7 9 NRC Staff Presentation Nuclear Island and Energy 10 Island Interface TR Review . . . . . . . . . . . .
11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
4 1 P-R-O-C-E-E-D-I-N-G-S 2 8:30 a.m.
3 CHAIR ROBERTS: This meeting will now come 4 to order. This is a meeting of the ACRS Subcommittee 5 for the TerraPower NATRIUM Design Reactor. I'm Tom 6 Roberts, Chair of the Subcommittee.
7 ACRS members in attendance are Ron 8 Ballinger, Juan, or Jose March-Leuba, Matt Sunseri, 9 Dave Petti, Joy Rempe, Bob Martin, Vicki Bier, Greg 10 Halnon, and Charlie Brown. Members online are Walt 11 Kirchner and Vesna Dimitrijevic. Can you please 12 confirm you're online?
13 MEMBER DIMITRIJEVIC: Yes, we are here.
14 Good morning.
15 CHAIR ROBERTS: Good morning, Vesna. And 16 Walt?
17 MEMBER KIRCHNER: Yes, Tom. Good morning.
18 CHAIR ROBERTS: Yes, good morning. And 19 consultants, we have Steve Schultz in the room, and 20 Dennis Bley online. Dennis, can you confirm you're 21 there?
22 MR. BLEY: I'm here.
23 CHAIR ROBERTS: Thank you. Now, Kent 24 Howard of the ACRS staff is the designated federal 25 official for the meeting, over there.
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5 1 Today the Subcommittee will discuss a 2 topical report submitted by TerraPower, and reviewed 3 by the NRC staff on the subject of independence 4 between the nuclear island and the energy island of 5 the NATRIUM design.
6 The topical report sets out to make the 7 case that all structured systems and components, or 8 SSCs, relied upon for reactor safety are on the 9 nuclear island. And events on the energy island are 10 sufficiently decoupled from the nuclear reactor that 11 the energy island can be considered to be non-safety, 12 and not require use of reactor safety standards in 13 design and construction.
14 These are more detail on this from the 15 applicant, as well as the contents of the direct 16 safety evaluation from the NRC staff.
17 The ACRS was established by statute, and 18 is governed by the Federal Advisory Committee Act, or 19 FACA. The NRC implements FACA in accordance with 20 regulations found in Title 10 of the Code of Federal 21 Regulations, Part 7.
22 We hold Subcommittee meetings to gather 23 information and perform preparatory work that will 24 square deliberation at a full Committee meeting if 25 necessary.
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6 1 The Committee can only speak to its 2 published letter reports. As with any ACRS meeting, 3 attendees should consider any remarks by ACRS members 4 are their personal comments and not Committee 5 positions.
6 The rule for participation in all ACRS 7 meetings, including today's were announced previously 8 in the Federal Register, and included on the ACRS 9 section of the USNRC's public website.
10 This website provides our charter, by-11 laws, agendas, letter reports, and transcripts of all 12 full and Subcommittee meetings, including presented 13 material.
14 As stated on the website, members of the 15 public who desire to provide written or oral input to 16 the Subcommittee may do so, and should contact the 17 designated federal officer five days prior to the 18 meeting as practicable.
19 We did not receive any written comments or 20 requests to make oral statements from members of the 21 public regarding today's session.
22 Today's meeting is open to public 23 attendance. And there will be time set aside during 24 the meeting for comments from members of the public 25 attending or listening to our meetings.
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7 1 Today's meeting is a hybrid meeting, 2 meaning there is both in person attendance and remote 3 capability via a Microsoft Teams link.
4 A transcript of today's meeting is being 5 kept. Therefore, we request that meeting participants 6 identify themselves when they speak, and speak with 7 sufficient clarity and volume so they can be readily 8 heard.
9 At this time, I ask all the attendees to 10 put their devices on mute, both the Teams computers 11 and cell phones, to minimize disruptions, and unmute 12 only when speaking.
13 We'll now proceed with the meeting. And 14 I'll call upon Mr. Nick Kellenberger from TerraPower 15 to make introductory remarks.
16 MR. KELLENBERGER: Good morning and thank 17 you, ACRS Subcommittee. We are excited for our first 18 Subcommittee meeting. We had a presentation earlier 19 this year on the overview of our plant, but this will 20 be the first, this is the first meeting on our, one of 21 our topical reports.
22 As the Chair said, I'm Nick Kellenberger.
23 I'm a licensing manager at Terra Power, and joined by, 24 to my left Eric Williams. He's the Senior Vice 25 President and design authority for the NATRIUM NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
8 1 reactor; George Wilson, who's our Vice President of 2 Reg Affairs and Licensing.
3 Also in the room, Emily Young, our manager 4 of deterministic safety analysis, and George Piccard, 5 who's our Site Director for Unit 1, first NATRIUM 6 plant. With that I'm going to turn it over to Eric to 7 walk us through the beginning. And then George will 8 take over near the end.
9 MEMBER MARCH-LEUBA: Sorry. These 10 microphones are very, very directional. All of the 11 people in the --
12 MR. WILLIAMS: Okay. I'm going to go 13 ahead and talk. If there's any problems with the 14 audio, just stop me and let me know. So, my name is 15 Eric Williams. Thank you for the introduction. And 16 I'm happy to be here to talk about this topical report 17 today.
18 We've lined up a presentation that goes 19 through the topics here. We're going to go back and 20 look at the reactor overview of the design. But since 21 we were here recently and explained the reactor 22 overview recently to the ACRS I'm going to more focus 23 on what's important for the topical report discussion 24 today. So, going through and pointing out the key 25 features of the energy island and nuclear island NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
9 1 interfaces, and things like that.
2 Then we're going to talk about operation 3 flexibility, and how the energy island is designed to 4 operate and take care of transients. We're going to 5 talk about what we mean by transient separation, so 6 that will get into some of the structure that we're 7 using to look at licensing basis events, and all of 8 the licensing modernization project approach.
9 And then we're going to end with 10 regulatory impacts. And George is going to take that 11 portion at the end. And so, really all of the 12 discussion is really designed to set up that 13 discussion on regulatory impact. So, we'll jump right 14 in.
15 All right. So here's the look that we 16 usually portray if we're talking about the NATRIUM 17 safety features. Some of the main differences to 18 other technologies are kind of tabulated there on the 19 left.
20 It is a pool type metal field sodium fast 21 reactor. A lot of the experience in the United States 22 has been with loop reactors. There's been a lot of 23 international experience on pool reactors.
24 So, that's one of the key aspects here 25 that's important to talking about the thermal inertia NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
10 1 that exists in the primary heat transport system.
2 Having the pool reactor in the large volume coolant in 3 the vessel is an important feature for that.
4 Metal fuel, and the specific design for 5 the NATRIUM reactor lead to a lot of the safety 6 features that we portray on this slide. The fact that 7 it's metal fuel, and it's metal coolant makes the two 8 very compatible with one another, which adds another 9 aspect to the safety case.
10 And the molten salt energy island is 11 another change that we've introduced into the design, 12 that we think adds a lot to the safety case. And 13 we're going to be talking a lot about that part today.
14 Other sodium fast reactors have had steam 15 gener -- had sodium steam generators, sodium water 16 steam generators. So that is one of the aspects that 17 we've eliminated by design. Because the sodium water 18 reaction is highly energetic.
19 What we now have are sodium salt heat 20 exchangers. So, we'll be introducing a lot about 21 those today in the discussion. And there is also an 22 exothermic reaction between sodium and salt that we've 23 mentioned before, much more benign reaction than 24 sodium and water. But still something that is 25 addressed in the design.
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11 1 And the large thermal inertia is something 2 that's going to come up a lot, not just in the primary 3 heat transport system, but the intermediate heat 4 transport system, and the salt system as well.
5 There's a lot of volume of coolant in those systems 6 that can absorb heat. So, those are kind of the key 7 aspects for setting up today's discussion. We've got 8 a --
9 MR. BLEY: Eric?
10 MR. WILLIAMS: -- fundamental safety --
11 Oh, yes.
12 MR. BLEY: This is Dennis Bley online. I 13 don't know that we talked about it last time. But 14 looking at this picture there's a lot of stuff inside 15 your pool. Can you say anything, just briefly, about 16 how you've set this up to be able to do maintenance 17 with such a compact design?
18 MR. WILLIAMS: Yes, sure. So, all of the 19 main components are designed to be removed and 20 replaced, or go through operation and maintenance.
21 So, even the kidney shaped intermediate heat 22 exchangers are designed to come out. The mechanical 23 primary sodium pumps can be removed.
24 There's a maintenance port as well in the 25 reactor vessel head that I don't think can be seen on NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
12 1 the diagram, that can be used to go in and hook up 2 different machines to perform maintenance.
3 And then of course you've got the 4 refueling equipment that mates up with the reactor 5 vessel head to maintain the fuel assemblies. So, we 6 are designing that for maintenance.
7 I think the picture gives the impression 8 of more congestion than there actually is. Certainly 9 in the center of the reactor vessel head, where the 10 control rods come in. That is a highly congested part 11 right there just due to the control rods, the 12 refueling. That's the rotating plug that handles the 13 refueling equipment as well.
14 So there's some congestion in that area.
15 But it's still a very large vessel. And we have the 16 equipment, you know. I think it looks a lot more 17 congested on the picture than it actually is. But --
18 MR. BLEY: Okay.
19 MR. WILLIAMS: -- the cool pools reopen, 20 yes.
21 MR. BLEY: Thank you. And at some point 22 in the future, if you guys have movies about this 23 operation will work it would be real helpful to see 24 that.
25 MR. WILLIAMS: Yes, definitely. Yes. We NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
13 1 can pull up the 3D model even, and rotate it around 2 and take a look inside.
3 MEMBER REMPE: Is the 3D model sufficient?
4 Or are you planning to do some sort of non-nuclear 5 prototype with all the widgets in there, and practice 6 maintenance as part of your development?
7 MR. WILLIAMS: We will be practicing some 8 maintenance in our test and fill facility. That's 9 designed to go on site in Wyoming as a way of 10 combining both some full scale testing of equipment, 11 as well as the facility needed to fill the actual 12 reactor with cilium eventually.
13 So, in that facility we'll be testing some 14 full scale prototypes. And some aspects of that will 15 be for maintenance operations as well, refueling, and 16 things like that.
17 MEMBER REMPE: Thank you.
18 MEMBER MARCH-LEUBA: While you were 19 discussing the figure, that bright red square on the 20 button, what is it?
21 MR. WILLIAMS: Yes. That's the heated 22 length of the fuel. So, you can kind of sense how 23 small that is compared to the amount of coolant that 24 you have.
25 (Off microphone comment)
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14 1 MR. WILLIAMS: Yes.
2 MEMBER MARCH-LEUBA: -- capacity.
3 MR. WILLIAMS: Right.
4 MEMBER MARCH-LEUBA: And the vessel is low 5 pressure obviously. And is on air. It's not in a 6 large cooling pool like --
7 MR. WILLIAMS: Right. You're actually 8 looking at two vessels. And hard to see. But you've 9 got a reactor vessel. And then surrounding that 10 reactor vessel is a guard vessel, and in between that 11 space is interim space using argon gas, so you 12 actually have two vessels there, and outside of that 13 guard vessel is air, and that is what cools the 14 reactor in emergencies, takes care of the decay heat 15 removal.
16 MEMBER MARCH-LEUBA: People contribute 17 sodium and moisture.
18 MR. WILLIAMS: Right.
19 MR. BLEY: Jose, if you can stay on the 20 mic it would help us out here.
21 MEMBER MARCH-LEUBA: I was talking into 22 the mic. So --
23 MR. BLEY: It's clear now. It wasn't 24 then.
25 MEMBER MARCH-LEUBA: After seven years NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
15 1 here I thought you would understand me. I mentioned 2 that there is no, I don't see any credible path 3 mixture between the sodium and water. Because there 4 is no water.
5 MR. WILLIAMS: Right.
6 MR. BLEY: Yes. Thanks.
7 MR. WILLIAMS: So, on the right of the 8 slide we've got our fundamental safety functions.
9 I'll just touch upon some of the differences here.
10 So, in control I think it's important to 11 point out the motor driven control rod run back.
12 That's something that comes up a lot in discussion 13 energy island transients that we don't need to scram 14 the reactor on. We just need to do a power run back.
15 The control rods are designed to handle 16 those run backs, to avoid the scram. So, that takes 17 into account the transients, the time constants that 18 exist throughout the integrated plans, to be able to 19 run back the power and avoid the scram. So, that's 20 something that we'll be discussing today.
21 There's also of course the gravity driven 22 control rod scram. And then we talked about the 23 inherent reactivity feedback. That's also a form of 24 reactivity control that comes from the design of the 25 core restraint system and the fuel itself.
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16 1 When we look at cooling, of course we call 2 this an in vessel primary sodium heat transport, or an 3 integrated reactor vessel. Meaning the entire primary 4 heat transport system is contained within the vessel.
5 That means the only primary fluid that 6 leaves this vessel is the cleanup systems, which are 7 small bore pipes that clean up the liquid sodium and 8 the cover gas inside the reactor vessel. All the 9 penetrations go through the reactor vessel head as 10 well.
11 There's also an intermediate sodium 12 system, because the primary coolant isn't leaving the 13 vessel. The intermediate heat exchangers give up heat 14 to an intermediate sodium system that carry the heat 15 out of the vessel and to the sodium salt heat 16 exchangers.
17 And within that system is also another 18 sodium to air heat exchanger that can run in both an 19 active mode and a passive mode.
20 And so, the active mode is what is going 21 to be used when we talk about a lot of the transients 22 today that run back the power down to five percent, 23 isolate from the energy island, and then remove heat 24 with these sodium air heat exchangers, using forced 25 flow mode.
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17 1 So, that's going to be the typical thing 2 that we'll come back to and refer to as the 3 intermediate air cooling system. It will also work in 4 natural draft flow as well.
5 So, there's some dampers that can open, 6 and just allowing natural draft you can get heat 7 removal there as well. And then the -- Yes.
8 MEMBER MARCH-LEUBA: Let me talk into the 9 microphone. You don't remember a part of your life 10 where you were not working on this design. But to us 11 it's new?
12 MR. WILLIAMS: Yes.
13 MEMBER MARCH-LEUBA: So, please try to 14 explain to us. So, those green heat exchangers I see 15 there are sodium to sodium?
16 MR. WILLIAMS: Yes.
17 MEMBER MARCH-LEUBA: And then the sodium 18 goes outside the vessel?
19 MR. WILLIAMS: The intermediate sodium.
20 MEMBER MARCH-LEUBA: The intermediate 21 sodium --
22 MR. WILLIAMS: Right.
23 MEMBER MARCH-LEUBA: -- goes outside the 24 vessel and heats up the salt?
25 MR. WILLIAMS: That's right.
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18 1 MEMBER MARCH-LEUBA: And that intermediate 2 sodium can also transfer heat to air in the 3 environment. Is that in site containment or is it 4 outside containment?
5 MR. WILLIAMS: Those exchangers are 6 outside.
7 MEMBER MARCH-LEUBA: Oh. So, it transfers 8 the heat to the environment?
9 MR. WILLIAMS: Yes. It does.
10 MEMBER MARCH-LEUBA: Try to --
11 MR. WILLIAMS: Okay.
12 MEMBER MARCH-LEUBA: You see here to --
13 MR. WILLIAMS: I will.
14 MEMBER MARCH-LEUBA: We don't know this.
15 MR. WILLIAMS: Okay.
16 MEMBER MARTIN: Yes. And I have a 17 question as well. Bob Martin, member. Regarding the 18 air cooling natural draft flow, that is strictly a 19 safety system, right?
20 MR. WILLIAMS: Yes.
21 MEMBER MARTIN: And during normal 22 operations you would isolate that? No. So, you get 23 parasitic heat losses?
24 MR. WILLIAMS: Yes. And that's okay.
25 That's okay. Yes. Yes. One of the key aspects to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
19 1 the reactor air cooling system, that's the third 2 bullet under cooling.
3 That's a system that's cooling the outside 4 of this guard vessel using air. Is that it's 5 primarily radiation heat transfer limited. So, it 6 runs on temperature to the fourth power. And so, it 7 takes the primary coolant heating up in order to kick 8 it into operation.
9 So, during normal operation you can accept 10 the parasitic heat loss. Of course, we'd like to sell 11 more electricity with that. But it's okay for the 12 benefit of having it always on, and nothing having to 13 move position or anything to kick it in other than the 14 fluid heats up. So, yes, that's the RAC erector 15 cooling system.
16 MEMBER PETTI: Just a question on the 17 height of the vessel.
18 MR. WILLIAMS: Let me think of the actual 19 number here. I think it's about, yes, between 50 and 20 60 feet tall, yes.
21 MEMBER BALLINGER: This is Ron Ballinger.
22 You're going to get beat up on the prototype versus 23 non prototype issue as we go along.
24 I seem to recall a very long time ago when 25 the French folks discovered that they couldn't find NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
20 1 the fuel after the irradiation, because of the 2 distortion. And with a constrained core you can limit 3 that I'm assuming.
4 But how do you deal, that's one case where 5 without a test it's going to be tough. Is it going to 6 be tough, do you think, to justify not making a 7 prototype?
8 Because without the irradiation damage on 9 the fuel you won't get the distortion, limited as it 10 might be because of the core restraint system, to 11 verify that the darn control rods will go in when 12 they're supposed to?
13 MR. WILLIAMS: Yes, so a lot of, I mean, 14 our fuel, we're relying on the database provided by 15 the Fastbucks test facility for our fuel, and we've 16 set the design of the Type 1 fuel to be very close to 17 what was used at FFTF for that reason.
18 And then, we're supplementing that with 19 quite a lot of four mechanical tests. We have a lot 20 of full scale tests that look at distortion. We 21 distort assemblies in our facility in Bellview, and 22 look at withdrawal and insertion forces on those.
23 We also do multi assembly core mechanical 24 tests to get additional data on anything that is 25 different with the NATRIUM fuel. And so, I think NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
21 1 we're relying on the database from FFTF as well as the 2 attesting that we've done got in our plan to make the 3 argument that that prototype isn't needed.
4 And then, to go to our advanced fuel then 5 we need years of operation with a lead test assembly 6 program in NATRIUM to build it back. So, we're 7 starting with the bootstrap method using a fuel design 8 that's very, very close to FFTF.
9 MEMBER BALLINGER: You're satisfied you 10 can make that case?
11 MR. WILLIAMS: Yes.
12 MEMBER KIRCHNER: Eric, this is Walt 13 Kirchner. Just clarification. My memory for FFTF is 14 oxide fuel. Did you have, did they, did Argon send 15 metal fuel for irradiation --
16 MR. WILLIAMS: Yes.
17 MEMBER KIRCHNER: -- experiments or data 18 in FFTF?
19 MR. WILLIAMS: Yes, they did. They did.
20 They were in the process of testing metal fuel. So, 21 they hadn't converted over to metal fuel or anything.
22 So it was an oxide fuel reactor with metal fuel 23 assemblies within it. So, we do have data on that.
24 And we've acquired those assemblies to do PIE on.
25 MEMBER REMPE: Now much fluence did they NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
22 1 get in FFTF?
2 MR. WILLIAMS: I don't know off the top of 3 my head. You could maybe contact somebody back --
4 MEMBER REMPE: Well, again, this, the 5 purpose of the meeting isn't on that. But that's 6 something to think about.
7 MR. WILLIAMS: Okay. We do have a, 8 George, remind us. We have a fuel qualification 9 topical report right now. Yes.
10 MR. PICCARD: Yes. We have several 11 reports, we just got back the draft form that will 12 talk about the new qualifications methodology and how 13 we're going to go through that, so it will be covered.
14 And it's on future topical reports in more detail.
15 MR. WILLIAMS: Okay. The last fundamental 16 safety function is contain. I don't think we're 17 talking too much about that today, because we're not 18 talking about releases.
19 But we have low pressure systems in the 20 plant. I think we mentioned that already. Low 21 pressure in the primary system that you see here. Low 22 pressure in the intermediate feed transport system, 23 and even in the salt system.
24 So, none of those systems are highly 25 pressurized. You won't get high pressure until you NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
23 1 all the way out to the steam generating system. So, 2 that helps quite a bit with the containment strategy.
3 We know that sodium has affinity for 4 radionuclides. So, we'll be factoring that into the 5 mechanistic source term analysis. And there's 6 multiple boundaries, you know.
7 There's an intact primary system like you 8 see here. And then there's, you know, a head access 9 area above the reactor vessel head. That's also 10 another layer of protection.
11 CHAIR ROBERTS: Eric, are we looking at 12 the containment right now, this thing, picture beside 13 --
14 MR. WILLIAMS: Essentially those are the 15 guard vessel surrounding the reactor vessel is part of 16 that.
17 CHAIR ROBERTS: What do you --
18 MR. WILLIAMS: And the seals --
19 CHAIR ROBERTS: -- as containment?
20 MR. WILLIAMS: Yes. So, that's a, it's a 21 series of SSCs that are credited. The guard vessel is 22 part of that. The reactor vessel head is part of 23 that. And the isolation valves on those two systems 24 that come out of the primary system for the cleanup, 25 I think those are also part of that.
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24 1 MR. WILSON: We'll have a functional, this 2 is George Wilson, TerraPower. We have a functional 3 containment design that will go from some of the EPZ 4 methodologies that we take credit for different 5 portions based on where we're at. So --
6 MR. WILLIAMS: Yes.
7 MR. WILSON: It would follow the SECY 8 paper if that was approved, that SRM that was approved 9 by the Commission on how to describe and go through 10 the functional containment. So, that will be further 11 discussed later.
12 MR. WILLIAMS: So, taking all that into 13 account you have a pretty simplified response to 14 abnormal events. And that group of bullets you see 15 there is really what we would be crediting in say a 16 design basis accident scenario with reliable reactor 17 shut down.
18 Then you transition to natural circulation 19 cooling. You use the reactor air cooling system, or 20 indefinite asset emergency heat removal. You've got 21 the low pressure functional containment. Then 22 there'll be no reliance on the energy island for any 23 safety functions.
24 No safety related operator actions for AC 25 power as well. And we've kind of already discussed NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
25 1 our basis in the legacy US SFR experience. All right.
2 Go to the next one, Nick.
3 So, this just shows a bird's eye view of 4 the site that's laid out. I think last time we were 5 here we didn't have quite the topology, the way it 6 really looks in Wyoming. So, that's kind of a nice 7 feature that's been added.
8 I don't think anything is significantly 9 moved around though, since we last discussed with you.
10 We're mainly talking about here the, well, if we talk 11 about the nuclear island first, you can see Buildings 12 1, 2, 3, and 4 in the center of the slide.
13 1 is the control building, 2 is the fuel 14 handling building, 3 is the reactor building where the 15 vessel that we saw on the prior side is in the reactor 16 building below grade. And then the reactor ox 17 building, which is Building number 4.
18 We're going to be talking a lot about the 19 equipment in that building today, because we're 20 talking about these energy island transients. And I 21 wanted to point out the question that often comes up 22 is the nuclear island salt system isolation valves, 23 and where they're located.
24 They're actually located at, just outside 25 of Building number 4, in the salt piping that is going NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
26 1 out to the salt storage tanks. And that's identified 2 with Label 5. 5 shows you the piping train that comes 3 out of the sodium salt heat exchanger, and goes out to 4 the storage tanks that you see on the energy island.
5 So, those isolation valves, there'll be 6 one on the hot side and one on the cold side, those 7 exist just outside of Building number 4, as close as 8 practical to it. So, that's where the break is where 9 we talked about the interface between the nuclear 10 island and the energy island where that break occurs 11 physically.
12 MEMBER HALNON: So, Eric, intermediate 13 cooling, forced cooling, is that the two structures 14 just to the left of the Number 5 circle there?
15 MR. WILLIAMS: No. Those would be close 16 to Building 4. I think it's that grey --
17 MEMBER HALNON: So, it's inside those --
18 MR. WILLIAMS: Yes.
19 MEMBER HALNON: Inside the nuclear island?
20 MR. WILLIAMS: It is in the nuclear island 21 yes.
22 MEMBER HALNON: We just don't see it.
23 MR. WILLIAMS: Yes. You'll see it a 24 little bit better on the next slide.
25 MR. KELLENBERGER: Yes. It's these two NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
27 1 tan towers to the left of 4. Those are the --
2 MEMBER HALNON: Okay. So, that's the 3 separation you have?
4 MR. WILLIAMS: Right.
5 MEMBER HALNON: Okay. Thanks.
6 CHAIR ROBERTS: This is Tom Roberts. Can 7 you talk some more about those valves? Are they, you 8 know, giant valves that shuts, isolates the flow on 9 that sub pipe? How big a pipe is that?
10 MR. WILLIAMS: It's about a 36 inch pipe.
11 So, it is designed to isolate the salt system, isolate 12 the nuclear island from the energy island. So, when 13 we do our power run back we'll reduce power to about 14 five percent. And then we'll isolate from the energy 15 island. And we'll take care of all the decay heat 16 removal.
17 Say if you're in a, even during an outage 18 for refueling, or something like that. We'll come 19 down and take care of all the heat removal using the 20 intermediate air cooling system, those sodium to air 21 heat exchangers.
22 MEMBER MARTIN: A clarification. Bob 23 Martin. To the right of seven is that like a air 24 cooling ultimate heat sink?
25 MR. WILLIAMS: Yes. That's the forced NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
28 1 cooling, cooling down --
2 MR. WILSON: It is not an ultimate heat 3 sink. That is just a cooling tower for the turbine, 4 for the condenser.
5 MR. WILLIAMS: Yes.
6 MR. WILSON: That has nothing to do with 7 safety. So --
8 MEMBER MARTIN: I wasn't using the 9 ultimate heat sink as a safety term. Because 10 obviously --
11 MR. WILSON: It just --
12 MEMBER MARTIN: -- heat loss --
13 MR. WILSON: It's condenser cooling for --
14 MR. WILLIAMS: Right.
15 MEMBER MARTIN: I'd like to -- And this is 16 your design? Not just a artist rendering, or anything 17 for --
18 MR. WILLIAMS: Right, yes.
19 MEMBER MARTIN: -- Linkedin, or something?
20 MR. WILLIAMS: Right.
21 MEMBER MARTIN: Last month we were at 22 Comanche Peak. And one of the things that impressed 23 me was just really how compact everything was. And 24 here I see a control room over here on the left in a 25 very linear layout.
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29 1 And now, part of the, you know, part of 2 the point is all this independence, you know, by 3 seeking. So, it's very obvious where you need to draw 4 a line.
5 But I have to wonder, when it comes to, 6 you know, a big part of your safety case is built on 7 the hazards of, so you're going to have PRA, what have 8 you. You're going to have maybe a fair amount of 9 cabling, electrical.
10 And I wonder whether your, you know, total 11 length of these activities, and just maybe just a 12 thermal inertia that you have there. Plus your pool, 13 your intermittent loop, your salt, and then the steam.
14 And in, so I'm wondering about the 15 responsiveness of the plant overall. Again, an 16 independent, you know, if you're trying to get a 17 dependence you're going to be a lot decoupled.
18 But even, you know, there's a trade off, 19 right, with the responsiveness of the plant. You're 20 going to have something as simple as load follow, 21 which makes your, you know, of course operators 22 impatient. The answer is an automatic control.
23 But all these sort of thing is going to 24 factor into I would say your PRA. And have you 25 considered how the physical layout like this, you NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
30 1 know, like the linear feet of your cabling and stuff 2 play into that? Is that on your mind?
3 MR. WILLIAMS: It's definitely on our 4 mind. I mean, we have built quite the integrated real 5 F5 model of this plant that takes into account all of 6 these interfacing systems.
7 We're also using that for the engineering 8 simulator, which is starting to come online. So, 9 we'll be running a lot of these transients to see 10 those different time constants and, you know, system 11 interaction type facts that come into play with these 12 things.
13 And right now it's actually looking very 14 beneficial from the standpoint of plant control. And 15 we'll get into a little bit of that when we get to a 16 slide coming up, about the difference between the 17 nuclear island operator and the energy island 18 operator.
19 But I think that that buffer of having the 20 salt tanks in the middle, in between these systems 21 does provide this very good divisional between the 22 two. So, it's not all so tightly coupled, because 23 those tanks kind of buffer things.
24 MR. WILSON: And this is George Wilson.
25 And we also have a human factor's evaluation topical NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
31 1 report coming in that you guys will get a look at 2 potentially later on, to address some of the comments 3 that you brought up.
4 MEMBER BIER: Yes. That was going to be 5 my follow up. This is Vicki Bier. Which is, so Bob 6 kind of mentioned just the linear feet of cable and 7 your piping, or whatever that may make it vulnerable.
8 But also, are there actions that are going to require 9 people going back and forth between the different 10 locations? Or --
11 MR. WILSON: Right now we're doing -- This 12 is George Wilson. We don't have any safety. We're 13 not taking credit for any operator actions. And we do 14 not have any safety related AC at all on the plant.
15 So the design itself addresses some of 16 your guys' questions, but will also address the human 17 factors. Like I said, there's topical reports that 18 are still being written, that's going to the NRC, that 19 you'll have, and so you will get a chance to have 20 additional questions to that.
21 MEMBER HALNON: Yes. And we went through 22 this in your last presentation about the location of 23 the control room, and whatnot. And you might think, 24 I understand that the picture itself, it's not a 25 quarter mile.
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32 1 MR. WILLIAMS: Right.
2 MEMBER HALNON: It's a pretty compact 3 plant. So, moving it 100 feet to the right is not 4 going to increase the responsiveness all that much, if 5 any. Because you may have to be walking around 6 buildings or through buildings at that point. So, we 7 did discuss some of this earlier on. So, really good 8 to see how responsive other topicals.
9 MR. WILLIAMS: Yes.
10 MEMBER REMPE: So, I have a different 11 question. I'm not sure if this is the place, or 12 later. But you always emphasize you're building upon 13 U.S. experience. And I'm thinking of the Japanese 14 experience in Monju.
15 And if your, some of this requires 16 instrumentation. And of course the leakage was from 17 somebody putting in a thermal couple that was not, was 18 susceptible to corrosion and leakage.
19 And are you going to have, and I looked 20 through the materials we were given at a different 21 level. But are you going to have some sort of 22 limitations to consider that you aren't going to have 23 some problems in the energy island that, and I'm 24 thinking co-located hazards, that if something were to 25 degrade, and that salt happens to have a problem, and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
33 1 people are responding to it, that it might adversely 2 affect the nuclear island.
3 MR. WILLIAMS: Well, I don't, I think, you 4 know, most of the problems that would be initiated in 5 the energy island, you know, would simply result in a 6 power run back.
7 Because you want to, if it's a big enough 8 problem you'd want to shut down the energy island, and 9 go do the repair. I think the good thing about this 10 plant is that you don't have to scram the reactor to 11 do that. You can take a power run back, put the 12 system through a much milder transient, much safer 13 transient to go down in power on the nuclear island.
14 There's also quite a bit of time before 15 you have to do that. We'll talk about it in a minute, 16 which is a big improvement I think.
17 So, I don't, I can't see right now why a 18 maintenance issue or a failing piece of equipment on 19 the energy island would ever impact the safety of the 20 nuclear island.
21 From a reliability standpoint it is very 22 important though. And we are trying to design a very 23 reliable energy island, probably more reliable than 24 what concentrated solar plants would want, or need.
25 So, you know, we want the high capacity NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
34 1 factors that nuclear plants expect, and so our energy 2 island will be designed with a high level of 3 reliability, so that will definitely be true now.
4 MEMBER PETTI: I understand that the 5 concentrated solar guys, the reliability is not very 6 good. What are you guys --
7 MR. WILLIAMS: Yes. We're looking at the 8 OE from the concentrated solar industry.
9 MEMBER PETTI: I mean --
10 MR. WILLIAMS: We're looking at the codes.
11 MEMBER PETTI: -- sold by them. It's 12 advisory.
13 MR. WILLIAMS: Yes. The codes that 14 they've applied to their systems, and different types 15 of failures that they've seen in the field. So, we're 16 in tune with all of that very closely. So, we're 17 taking that into account in our design.
18 And the interesting thing though is just 19 that that, with their low capacity factors they don't 20 really necessarily need the same reliability that we 21 do. So, that is something that we're paying attention 22 to.
23 MEMBER BROWN: Question. You mentioned 24 there's no safety related electrical systems at all.
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35 1 supplant as part of the nuclear island. And it's got 2 four divisions. And how do you maintain --
3 MR. WILSON: I meant that --
4 MEMBER BROWN: -- power --
5 MR. WILSON: -- there's no backup. We 6 don't have any safety related diesel generators, or 7 anything like that. We don't have any --
8 (Simultaneous speaking) 9 MR. WILSON: That's right. You'll have 10 RPS. And you also have all the PAMs instruments.
11 MEMBER BROWN: Is there one system set up 12 to have redundant run back capability? In other 13 words, redundant systems to drive those? That seems 14 to be --
15 MR. WILSON: There's logic --
16 MEMBER BROWN: -- the primary thing. So, 17 that's what I'm talking about.
18 MR. WILSON: Yes. There's logic.
19 MEMBER BROWN: Like the SS4 division. And 20 just so the run back obviously is there to bring the 21 power down during operations if you have difficulties, 22 so you don't have to scram.
23 And I was curious. They didn't talk about 24 having any redundant channels or divisions for that.
25 It sounded like a one division, one off sort of.
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36 1 MR. WILSON: It may be later --
2 (Simultaneous speaking) 3 MR. WILSON: We have a topic report to 4 talk about the nuclear island control system. We've 5 had interactions. And the RPS system will go through 6 the design review guide. But there's multiple 7 channels. And we have logic --
8 MEMBER BROWN: Okay. All right.
9 (Simultaneous speaking) 10 MEMBER BROWN: Thank you.
11 MEMBER MARTIN: There's a question.
12 You've, of course already, George, mentioned, you 13 know, safety related components, what have you. We're 14 safety related this, that at this stage, at least of 15 your interaction with ACRS.
16 As far as I know, not seeing any kind of 17 safety classification methodology. I see, you know, 18 you go through a hazard, a PRA, what have you.
19 There's a methodology to making those claims.
20 All I hear is claims, arguments. But as 21 far as I know have you sent something to the staff 22 that explains the classification methodology?
23 MR. WILLIAMS: Yes. We've had 24 interactions with the staff, and how we've utilized an 25 AI 1804, and how we're doing our SSE classification, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
37 1 how we're doing our design base and licensing basis 2 events. We've had all those interactions. And we've 3 written topical reports and white papers to the staff.
4 MEMBER MARTIN: Okay.
5 MR. WILLIAMS: So, there's a series of 6 topical reports that we still have to submit to the 7 staff. And the staff has received several topical 8 reports already.
9 MEMBER MARTIN: Okay. Maybe I'll save my 10 question for the staff.
11 CHAIR ROBERTS: Yes, this is Tom Roberts.
12 One more question. And I hope we can get it off the 13 slide. Part of what Joy was asking. Did you look at 14 potentially catastrophic events happening in the 15 energy island, like something, you know, something 16 blows up due to a chemical reaction? Or, you know, a 17 exothermic reaction of the salt with something?
18 I don't know. But, it's I don't really 19 see in the topical reports talk about how that would 20 not affect operations on the nuclear island.
21 MR. WILLIAMS: Well, our licensing basis 22 events are, and our initiating events that we're 23 screening are all driven by failure modes and effects 24 analyses on the equipment.
25 So, we are looking at from a fundamental NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
38 1 standpoint how each piece of equipment can fail.
2 We're not seeing anything like an explosive reaction 3 in the salt tanks, or anything like that. Because 4 salt isn't interacting with air.
5 You know, if you get a salt leak from a 6 tank it freezes in the air. It solidifies and comes 7 as this white powdery stuff that you clean up with a 8 shovel.
9 We are addressing the potential for 10 flooding from, you know, a catastrophic failure of the 11 tanks using berms that you don't actually see in this 12 diagram. But they would direct the flooding away from 13 the nuclear island.
14 And then it's about, you know, impact of 15 failures, you know, that have to go all the way 16 through the energy island salt piping, through the 17 nuclear island salt piping, and to the sodium heat 18 exchangers, sodium air heat, sodium salt heat 19 exchangers. Through those to the intermediate heat 20 transport system and through the IHX to the primary 21 pool.
22 So, it's all about kind of impact from the 23 energy island and make it through all of that to any, 24 you know, adverse any fundamental safety function, 25 which we're saying it cannot based on our simulations NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
39 1 that we've done.
2 So, we are looking at things like, you 3 know, salt hammer type events. If those isolation 4 valves close quickly, you know. Things like energy 5 island salt pump trips, and things like that.
6 So, all of those things that can happen on 7 the energy island are being studied. They're part of 8 the design. And we have a design requirement that 9 they shall not impact the nuclear island.
10 So we'll be continuing to, you know, if 11 anything changes we'll be continuing to look at that, 12 but we're not seeing anything like an explosion in the 13 tanks or anything of that nature, because we don't see 14 a precursor for that.
15 CHAIR ROBERTS: Okay. Thank you. Yes, in 16 theory an explosion in the energy island could affect 17 habitability in the control room, or any of a number 18 of direct mechanical effects on the nuclear island.
19 So, I'm glad to hear you're looking at that.
20 MR. WILLIAMS: Yes.
21 MEMBER MARCH-LEUBA: And, Tom, this time 22 I wanted to answer the previous question. Is it okay?
23 MR. ANZALONE: Yes, thanks. Is there a 24 microphone up here? Okay.
25 MEMBER REMPE: I think it's the top one.
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40 1 MR. ANZALONE: Okay. Thanks. Yes. I 2 just wanted to clarify that we're going to be talking 3 about the safety. Oh, sorry. Reed Anzalone from the 4 staff. We're going to be talking about the safety 5 classification process in our presentation. So, happy 6 to address the question then.
7 MEMBER MARCH-LEUBA: Thank you.
8 MR. WILLIAMS: Thank you. So, just to get 9 off this slide, you know, Building 6 is where the 10 steam generator equipment is. And Building 7 is where 11 the turbine haul is. So, we'll go to the next slide.
12 And this one is looking at the three 13 central nuclear island buildings, as if we're standing 14 at the energy island looking back towards the nuclear 15 island.
16 So, if you're looking, if you ever go back 17 and flip back and forth between the two slides, you're 18 looking backwards to the nuclear island here.
19 So, in the middle you see the reactor 20 building. You can see the reactor vessel, guard 21 vessel. Below grade there, you can see the pipes for 22 the intermediate heat transport system that come out 23 of the reactor vessel head. And they make their way 24 over to the reactor auxiliary building, above grade.
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41 1 exchangers live. They're above grade in that 2 building. There's two of them per train. And there's 3 two trains.
4 And so, that's where the intermediate heat 5 transport system interfaces with the nuclear island 6 salt system, and transfers heat from the sodium to the 7 salt.
8 There is also some discussion in the 9 topical report about drainage. You know, in cases 10 where you need to go into a long term outage you would 11 drain. You could drain both the sodium and the salt 12 system from, sodium from that heat exchanger. So, 13 there's drain tanks for both of those.
14 If there was a leak in the sodium salt 15 heat exchanger you would also initiate a drain, so 16 that you could, you know, terminate that interaction 17 between sodium and salt, and go in and take care of 18 the leak.
19 So, the sodium and salt drain tanks are 20 both below grade in the reactor ops building. So, 21 that's where those will be physically located.
22 You can see the salt piping going out to 23 the thermal storage system over there on the left.
24 That is where those NSS isolation valves will be 25 located.
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42 1 And you can see the intermediate air 2 cooling heat exchanger up at the top there, above the 3 reactor ops building. That's what we call the air 4 heat exchangers of the intermediate air cooling 5 system.
6 It's connected to, there's one of those 7 connected to each of the intermediate heat transport 8 loops. So, there's two of those in the design. And 9 like I said earlier, they can run in forced flow 10 cooling mode, where there is actually blowers blowing 11 air across the coils of the heat exchanger.
12 It can also run in natural draft mode, 13 where the dampers open and just allow natural draft 14 air flow over the coils. And that's the system that's 15 used in a lot of these run backs, and certainly in 16 refueling mode. Yes, question.
17 MEMBER KIRCHNER: Eric, this is Walt 18 Kirchner. A couple of questions. The sodium salt 19 heat exchangers, you mentioned earlier that sodium 20 salt mixtures are exothermic.
21 Since these are solid systems, in terms of 22 solid liquid during normal operation, is there the 23 potential for propagating a, energy back into the 24 primary vessel?
25 MR. WILLIAMS: They're actually not solid.
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43 1 There is a drain tank in the intermediate heat 2 transport system. So, there's a cover gas on that 3 drain tank.
4 MEMBER KIRCHNER: Yes. I see you have an 5 argon, a pre surface argon cover gas.
6 MR. WILLIAMS: Right. Right. And we can 7 detect the leak in a number of ways. And either 8 initiate a run back, or if it propagates to, you know, 9 a loss of heat transfer at the IHX, then it would be 10 picked up by one of the scram set points in the 11 nuclear island, if that were to happen.
12 MEMBER KIRCHNER: I'm not so much worried 13 about it leaking into one of your compartments.
14 Although that would be a concern from a fire 15 consideration.
16 But my concern would be, any energy 17 transfer due to an exothermic reaction between the 18 salt and the sodium. That could pressurize the 19 system.
20 MR. WILLIAMS: Yes. That is something we 21 are looking at though. That will be looked at in our 22 models for any sort of pressure wave that could make 23 its way back to the IHX. So, that would be something 24 that we would definitely look at.
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44 1 be important. The other Achilles heel these systems 2 in the past has been the air cooling system for decay 3 heat removal.
4 So, can you tell us a little bit more 5 about this? This intermediate air cooling, is that 6 sodium to air?
7 MR. WILLIAMS: That's right. Sodium to 8 air. So, you have your intermediate heat transport 9 loop. And you have a leg that comes off of the main 10 pipe. And it goes out to this sodium air heat 11 exchanger. Like I said, there's one in each loop.
12 And it's always running through there.
13 And so, what needs to happen is, for natural draft air 14 cooling the dampers would open to allow more air to 15 flow. If it's going into forced cooling mode then the 16 dampers open and the blowers turn on to remove heat 17 from that heat exchangers.
18 So, it's one of the workhorse components 19 that we have. Because it's always used in a run back.
20 It's always used as the main go to system for taking 21 care of decay heat when you're not in a, you know, 22 emergency situation.
23 MEMBER KIRCHNER: Right. So, this system 24 would have isolation valves on it should you get a air 25 a leak to air. I mean, the concern would be a fire or NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
45 1 other energetic events that could result from leaks in 2 the system.
3 MR. WILLIAMS: Yes, yes. If there were to 4 be a leak in the system that would probably be a drain 5 dilute kind of situation.
6 MEMBER KIRCHNER: Okay. Thank you.
7 MEMBER MARCH-LEUBA: You mentioned the 8 intermediate air cooling has AC power blowers? But 9 they're not required for decay heat.
10 MR. WILLIAMS: Right.
11 MEMBER MARCH-LEUBA: Only during --
12 MR. WILLIAMS: Right.
13 MEMBER MARCH-LEUBA: -- the low power.
14 MR. WILLIAMS: Right, yes. Only during 15 low power --
16 MEMBER MARCH-LEUBA: The decay heat safety 17 removal is the air ducts?
18 MR. WILLIAMS: Yes. It's the air ducts.
19 So, that would be reactor air cooling ducts. You're 20 seeing two of them there in the reactor building.
21 MEMBER MARCH-LEUBA: So, I'm going back to 22 my, everything above grade is susceptible to missiles 23 that can impact. You can live without that? Can you 24 live without the air cooling ducts?
25 MR. WILLIAMS: We can live without a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
46 1 certain, we can take a certain amount of degraded 2 performance in the reactor air cooling system. It's 3 actually very robust in fact to say pressure drops and 4 things like that.
5 As long as you have that radiation heat 6 transfer going between the guard vessel and the 7 reactor vessel, then the system performs very well.
8 We will, I mean, obviously be quantifying how much 9 degradation we can handle.
10 And, you know, in the PRA, you know, 11 looking at, it's part of the aircraft impact analysis 12 that we have to do, so there's a lot. At some point, 13 you can, you know, block up all the air ducts, and 14 then, you know, you'll probably bring in some 15 equipment from off site to unblock the duct or 16 something, you know, in that beyond design basis 17 regime, but we're still working through all that.
18 MEMBER MARCH-LEUBA: You mentioned time 19 constant will play a significant factor; you're 20 talking --
21 MR. WILLIAMS: No, yes. Right.
22 MEMBER HALNON: Eric, one last question.
23 Since the fuel is in sodium, the spent fuel's in 24 water, can you just talk to me about how that 25 transition is done, so that you don't get a problem --
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47 1 MR. WILLIAMS: Oh, yes.
2 MEMBER HALNON: -- when you insert it in 3 water?
4 MR. WILLIAMS: Storage, yes. That's very 5 carefully. So, fuel comes out. Obviously, I should 6 have mentioned this. But the fuel actually goes into 7 an in vessel storage location outside of the reactor 8 core barrel when it is done in the core.
9 And it cools off there for a cycle, inside 10 the vessel, before it even comes out. So that's a, 11 you know, a unique feature I think of a lot of sodium 12 bass reactors, pool reactors especially I think.
13 So, it cools off a little there, comes out 14 of the vessel. And then it gets transferred to an X 15 vessel storage tank, which is filled with sodium. And 16 it goes there during the outage. And you collect all 17 of your assemblies there.
18 And then after the outage you go in and 19 process them. And what you would do to put them into 20 the spent fuel pool is, you would take them out, and 21 they would go through a pool immersion cell, PIC, 22 which is a pit. It's probably one of those that you 23 see below grade over in the field handling building.
24 And it goes into that container. And what 25 we do is we blow initially dry nitrogen over that, to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
48 1 just blow off any sodium that is remaining, and 2 gradually turn up the humidity on the nitrogen very 3 slowly and carefully until any water in the nitrogen 4 is able to react with the sodium in any crevices or 5 things like that, until it's all removed.
6 And then finally when that is performed it 7 gets moved over to the spent fuel pool. So, and 8 during that whole migration, you know, it is handled 9 very carefully, taken through systems that have 10 barriers between it and air through inerted 11 environments, so that there's no chance of contact 12 with, the sodium on the fuel assembly with the air in 13 the reactor.
14 So yes, sometime I'm sure we'll go through 15 that whole process in detail. Yes. All right. I 16 think that --
17 CHAIR ROBERTS: This is Tom Roberts. I 18 was going to point out that we're about 40 minutes 19 into, essentially into the presentation with five 20 slides done. So, just --
21 MR. WILLIAMS: Okay.
22 CHAIR ROBERTS: -- keep that in mind and 23 try to maybe pick up the pace a little bit, and hold 24 the questions if possible. Thank you.
25 MR. WILLIAMS: Yes.
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49 1 MEMBER REMPE: We always blame the 2 Subcommittee.
3 MR. WILLIAMS: Okay. So now we're looking 4 back towards the energy island. You can see in the 5 picture to the right the energy island salt piping 6 that's coming back.
7 You've got pipes going from the cold salt 8 tank that go back to the nuclear island. And pipe 9 that goes from the sodium salt heat exchanger to the 10 hot salt tank. So, they're all contained within that.
11 One thing I wanted to point is, you see 12 several of the green lines that are coming, going into 13 the steam generator building. That's because we have 14 five steam generator trains, and the hot salt tank has 15 five pumps that go into, one per steam generator 16 train.
17 Off the cold salt tank, you also see quite 18 a few pumps and lines there. That's the attemperation 19 pumps that come off of the cold salt tank and go over 20 and mix into the salt coming out of the hot salt tank.
21 And then you can see a process flow 22 diagram down there at the bottom left. A lot of the 23 typical equipment that you see in a steam generator is 24 contained on this.
25 There are again five of these steam NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
50 1 generator system trains. So, if we just take from the 2 left to the right, you can see hot salt coming out of 3 the tank there.
4 It goes into both the super heater and a 5 reheater. The reheater takes some cold reheat from 6 the turbine extraction, and sends it back as hot 7 reheat.
8 The evaporator starts to bring the 9 feedwater up to saturation in the steam drum. And 10 then that goes over to the super heater to super heat 11 the steam, and send that off to the turbine.
12 We also use some of the salt to preheat 13 the feedwater over there on the right. And so that 14 essentially completes that circuit.
15 We have looked at, you know, transients 16 where you lose that cold salt, that salt return to the 17 cold salt tank. And we can go quite a bit of time 18 without that cold salt return before we have to do 19 anything on the nuclear island to adjust power, or 20 take the plant down, rather.
21 So, that is something that we've looked at 22 with our transient analysis. And we'll continue to 23 be, you know, checking that as we go through the rest 24 of the design.
25 MEMBER HALNON: Are the two tanks, hot and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
51 1 cold, are they identical?
2 MR. WILLIAMS: Yes.
3 MEMBER HALNON: And so the same?
4 MR. WILLIAMS: Yes.
5 MR. SCHULTZ: Eric, the transient analysis 6 that you did associated with the Energy Island, those 7 calculations are done with what methodology? Staff 8 had some comments during their audit associated with 9 the pedigree of the evaluation.
10 MR. WILLIAMS: Yes. Those were done as 11 part of our integrated plant analysis work, 12 specifically looking at all of the ASME design 13 transients, level A, B, C, D. And some of those then 14 get run over in the SAS code as part of looking at 15 these transients from a DBA perspective.
16 So we kind of used the best estimate 17 methodology to look at the ASME design transients and 18 then those factor in. If something like that were to 19 make its way into a DBA, then we would look at a 20 different methodology for safety analysis.
21 The transients that were looked at by the 22 staff, I think we had one calculation that used SAS, 23 but most of them were using 3D.
24 MR. SCHULTZ: Okay. The staff just 25 mentioned that they hadn't taken a look at those in NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
52 1 terms of code review and so forth.
2 MR. WILLIAMS: Okay.
3 MR. SCHULTZ: That could be something that 4 is done in the future?
5 MR. WILLIAMS: Yes.
6 MR. SCHULTZ: Thank you.
7 MR. WILLIAMS: Yes. Those were 8 preliminary. This topical report, which was submitted 9 in October of '22, was based on a conceptual design of 10 the plant.
11 So I think it did a really good job of 12 showing us these various time constants that exist in 13 the system and how robust the design is to have this 14 sort of independence between Energy Island and Nuclear 15 Island. We know that we will be repeating these 16 analyses as we proceed through the design.
17 MR. SCHULTZ: The staff mentioned all that 18 in their audit report and also came to the same 19 conclusions regarding the results. Thank you.
20 MR. WILLIAMS: All right. Let's go to the 21 next slide. We'll talk a little bit now about 22 operational flexibility. These are really the talking 23 points for the next slide, so why don't I just speak 24 to this as we look at the picture on the next slide.
25 We're kind of seeing two sides of the view NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
53 1 here. The side on the left is the view from the 2 Nuclear Island operator and the side on the right is 3 from the view of the Energy Island operator.
4 On the Nuclear Island side, we're going to 5 have licensed reactor operators controlling reactor 6 power. This allows the Nuclear Island operator to 7 really focus on the safety of the plant.
8 As long as the cold salt tank is flowing 9 appropriately into the sodium-salt heat exchangers, 10 we're not going to be affecting any of what we call 11 the interface parameters between the Energy Island and 12 the Nuclear Island that would cause a scram or 13 anything like that. So that's kind of the view from 14 the Nuclear Island standpoint.
15 From the Energy Island standpoint, the 16 grid operator is able to then control the turbine to 17 meet the electricity demand of the grid. As long as 18 the Energy Island operator is managing the inventory 19 between the hot and cold salt tanks, they won't be 20 triggering a runback.
21 They can manage that any way they want.
22 They can turn back electricity production. They can 23 increase electricity production. Whatever is required 24 to maintain a certain minimum cold salt tank level, 25 they can do that without recourse through the Nuclear NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
54 1 Island.
2 And so one of the things we look at is 3 what does that cold salt tank minimum level need to 4 be. For example, you would take the height of salt 5 required to provide net positive suction head to the 6 cold salt pumps.
7 Add to that the amount of salt that you 8 need to do a runback, to consume the runback, and add 9 to that the amount of salt you need to consume to 10 isolate the two systems from one another. And then 11 say to the Energy Island, don't go below that.
12 That would be a way of giving that Energy 13 Island operator flexibility to meet the grid demand 14 without impacting the Nuclear Island at all, and 15 always maintaining the reserve that you need to do a 16 proper runback without having to scram the plant.
17 MEMBER HALNON: Eric?
18 MR. WILLIAMS: Yes.
19 MEMBER HALNON: When everything is working 20 right, that sounds great. What happens when, say, the 21 dispatch calls for more power than what the Energy 22 Island can produce?
23 Are those controls and limits things that 24 cause some kind of action? You can control your 25 operators on-site and you can train them, but you're NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
55 1 not going to train the dispatcher.
2 MR. WILLIAMS: Yes. That all has to be --
3 control bands, alert levels, response times, all of 4 that has to be factored into what the grid operator is 5 doing. I don't know if we want to say any more about 6 how the grid operator would react to those things.
7 At some point they hit a limit and they 8 can't provide any more electricity. Or if they're up 9 at the maximum electrical output of 500 megawatts 10 electric and the grid still demands more but they've 11 depleted the hot salt tank, then they would have to 12 dial that back.
13 MEMBER HALNON: I guess I was more 14 thinking of low-power operation where you're a little 15 overambitious in saying, you've got a big hot salt 16 tank there. I can grab more than what you're 17 producing right now and hopefully meet the curve 18 somewhere in the middle before you run out of hot 19 salt.
20 We can talk later, but it would be 21 interesting to talk through those types of scenarios 22 to see how the systems would react. It's probably 23 controls on the Energy Island to find the dispatch, 24 but that interface was a big deal in commercial 25 reactors between the grid operator and the control NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
56 1 room.
2 MR. WILSON: This is George Wilson. We 3 have monthly meetings with PacifiCorp to go over this.
4 We talk with their compliance people and their grid 5 people. We're coordinating all this now and looking 6 at it.
7 We haven't finalized the procedures, but 8 we're starting to talk about compliance because it's 9 also new for them to get a nuclear plant on their 10 grid. There's additional standards that are going to 11 apply to them now. So we're still working with them, 12 doing the coordination. George's group is leading.
13 MEMBER HALNON: I guess my point is if 14 there's some things beyond your control that you need 15 to look at from the Energy Island and how that might 16 affect the Nuclear Island.
17 MR. WILLIAMS: That's a good point.
18 MEMBER KIRCHNER: This is Walt. Just to 19 kind of add onto your line of questioning, Eric or 20 George, could you give us a feeling of what's the net 21 output from the reactor versus the net output from the 22 steam plant, from the Energy Island?
23 And what's the time constant between the 24 two? Where I'm going with this is, what's the steady 25 state, and then what would be the peaking factor? How NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
57 1 would that feed back on the reactor system?
2 Or Greg went through a scenario where 3 you're dumping, you're reducing power. You mentioned 4 500 megawatts of electric for the Energy Island.
5 What's the equivalent from the reactor? How much can 6 you store?
7 How are you sizing that hot tank such that 8 when you look at that operational interface, you're 9 going to have a time constant that will run the 10 reactor itself up and down in terms of thermal 11 transients?
12 MR. WILLIAMS: So the design is for the 13 reactor to run a steady-state, full-thermal power.
14 We're not cycling back to any sort of load following.
15 We're doing the load following purely on the Energy 16 Island side.
17 MEMBER KIRCHNER: Yes.
18 MR. WILLIAMS: So in thermal equilibrium, 19 the reactor is putting out the equivalent of 345 20 megawatts electric. And the Energy Island is 21 providing 345 megawatts electric to the grid for a 22 period of time, between four or five hours let's say, 23 you can go up to 500 megawatts electric or you can go 24 down to 100 megawatts electric.
25 If you're in a daytime scenario and all of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
58 1 the renewables are online and you want to dial back 2 the system, you can dial it back as low as 100 3 megawatts electric. That's just a limitation of your 4 turbine design.
5 You can change that, if you want, with a 6 different design. All of the equipment beyond those 7 tanks are designed in size for 500 megawatts electric, 8 whereas all of the equipment on the Nuclear Island 9 side before the tanks is all designed for 345 10 megawatts electric.
11 MEMBER KIRCHNER: Okay. Thank you.
12 MEMBER MARCH-LEUBA: From the top of your 13 head, in units of power for 500 megawatts electric 14 operation, how big is the hot tank? Four hours, 12 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br />, 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />?
16 MR. WILLIAMS: Yes. It's between four and 17 five hours.
18 MEMBER MARCH-LEUBA: Only four to five 19 hours2.199074e-4 days <br />0.00528 hours <br />3.141534e-5 weeks <br />7.2295e-6 months <br />?
20 MR. WILLIAMS: Yes.
21 MEMBER MARCH-LEUBA: For the renewable 22 it's 12, right? The nighttime is 12?
23 MR. WILLIAMS: Right, but the peaks really 24 only last for that period of time. The peak in the 25 evening and then the peak in the morning, we have NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
59 1 people that are waking up. Yes.
2 MEMBER MARCH-LEUBA: Obviously, it doesn't 3 compromise the tanks?
4 MR. WILLIAMS: Right, no. That's 5 optimized for Wyoming. If you went to somewhere else, 6 you might have a different --
7 MEMBER MARCH-LEUBA: And you would just 8 have to change the size of the tanks?
9 MR. WILLIAMS: You can change the size of 10 the tanks. You can have additional pairs of tanks if 11 you need more storage. You can have additional 12 turbines if you want lower turndown.
13 There's a lot of optionality on the Energy 14 Island and a lot of flexibility. It's the Nuclear 15 Island we want to standardize and run full-power all 16 the time. So yes, very flexible.
17 MEMBER MARCH-LEUBA: Do you envision 18 having to sell megawatts electric at a loss? There's 19 sometimes in which nobody wants your power.
20 MR. WILLIAMS: Right, yes. We're not 21 designing for that.
22 CHAIR ROBERTS: Following up on Greg's and 23 Jose's questions, it looks like from the reactor 24 safety perspective, your biggest concern would be a 25 low demand, which is going to basically drain the cold NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
60 1 tank and fill the hot tank. Is there some minimal 2 level that is essentially a tech spec that if you go 3 below that, you do have a reactor safety concern?
4 MR. WILLIAMS: I think the power runback, 5 what happened before that. I'm sure there are even 6 lower limits that would be tech specs on the tanks 7 perhaps.
8 CHAIR ROBERTS: Tech spec would seem to 9 imply safety-grade instrumentation and that kind of 10 thing to measure it. I was trying to understand how 11 you can maintain the separation when the cold tank 12 level really is a factor in reactor safety.
13 MR. WILLIAMS: Yes. I guess in a future 14 slide here we're going to talk about the interface 15 parameters a bit. And actually, on this next slide is 16 where we have them listed. These are the things that 17 we would be looking at from a safety perspective.
18 If you go to the next one here, this is 19 where we start talking about separation. These are 20 the parameters that we really think of in terms of 21 something that would start to have an effect, would 22 start to propagate through the IHD and then to the 23 PHD.
24 We've looked at all the failures that 25 could occur out there in the Energy Island, all the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
61 1 way to complete loss of salt flow, which is probably 2 the most bounding of all of them. Just have all of 3 the salt tanks stop running. That would be even worse 4 probably than hitting a low level in the tank or 5 something like that.
6 And so they all come down to either a loss 7 of or reduced heat removal from the intermediate heat 8 transport system because of something that happened 9 out in the Nuclear Island salt system or an increase 10 in heat removal on the intermediate heat transport 11 system.
12 And so these are the parameters that we 13 would probably be looking at more, not so much the 14 tank levels but things closer to the sodium and salt 15 heat exchanger, such as a loss of salt flow that would 16 be detected in the Nuclear Island salt system, a high 17 salt temperature coming out of the sodium-salt heat 18 exchanger, or low salt pressure that might indicate a 19 leak.
20 On the increased heat removal side on the 21 IHD, you can have increased salt flow from a pump 22 over-speed condition or low salt temperature that 23 might be introducing an overcooling transient on the 24 primary system.
25 So these are actually the parameters that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
62 1 we would look at. They kind of decouple ourselves, if 2 you will, from the Energy Island. Things that happen 3 on the Energy Island can be taken care of by the 4 Energy Island operator. They can be taken care of 5 with power runbacks.
6 You would have to propagate out to these 7 parameters to start impacting the primary system 8 through all those time constants. And so when we ran 9 our transients and showed those to the staff, we were 10 looking at transients and examples of these different 11 parameters that get triggered.
12 And then you have things even further out 13 beyond the tanks like turbine trips, steam generator 14 malfunctions, equipment like that that would be 15 further away from the sodium-salt heat exchanger that 16 would probably start to trip equipment on the Energy 17 Island due to asset protection, and eventually would 18 trigger one of the runbacks at points to go back and 19 run the system back normally.
20 MEMBER PETTI: I don't think you answered 21 the question. I understand these events, what they 22 could do, and how they could challenge it, but I 23 thought Tom's question was the case of low power and 24 the salt level in the cold tank is also really low.
25 It's sort of an operational condition that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
63 1 you could somehow get into a different problem. I 2 guess I didn't see how these transients capture that 3 question.
4 MR. WILLIAMS: Yes. If we think about 5 operating the plan and delivering electricity from the 6 grid where you've depleted the cold salt tank level 7 down to the lowest that you're allowed, you would 8 still have, based on what I was talking about a few 9 slides ago about sizing that minimum level, you would 10 still have enough salt to do the runback and to 11 isolate the system and still have enough for net 12 positive suction ahead of the pumps.
13 So that level was designed to only allow 14 the Energy Island to operate when it's reserving that 15 amount of salt to go ahead and do a runback of the 16 plant. It's not designed to go below that.
17 That kind of gets back to Greg's question 18 over there. You would have to stop producing 19 electricity if you got to that level. You'd have to 20 manage that inventory within the limits provided to 21 the Energy Island.
22 MR. WILSON: This is George Wilson. We 23 haven't developed it but we'll develop system 24 operating procedures, conditions, and limits. It'll 25 be in those system operating conditions and limits NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
64 1 that you'll have normal operating bands. We just have 2 not done those.
3 So to address your question fully, all 4 that stuff will be covered when we have our operating 5 procedures when we've completed them.
6 MEMBER HALNON: And that comes back, 7 George, to a fundamental question on the operator.
8 Even though you say that there's no events that the 9 operator has to respond to, is there a condition where 10 the operator is required to maintain a certain 11 operating envelope to maintain pre-existing conditions 12 so that no response is such as required?
13 The fundamental question is if they're 14 required to keep it within an operating band, is the 15 operator not in essence responding to a license-based 16 event by maintaining the operational boundaries, if 17 you will, in place?
18 MR. WILLIAMS: This is George Wilson. If 19 you do it by design, I can have design intake have the 20 systems take action. I wouldn't have to rely on an 21 operator. It would be a fall-back, but I could have 22 the system take action. As Eric was saying, transient 23 runbacks and you essentially get a scram.
24 George, did you want to add?
25 MR. PICCARD: Yes. George Piccard from NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
65 1 plant operations. I will just add to that there is 2 little difference in how you would maintain with a 3 design margin and then an operational margin and other 4 types of operational primers of the amount of salt you 5 want to reserve in the cold tank.
6 You have to have a certain amount of water 7 in the tank. It would be the same type of procedural 8 guidance. You would have a design basis and then an 9 operational margin.
10 Some additional operational margins before 11 you load the dispatcher to actually control anything, 12 you would have even more margin to how much salt 13 reserve you'd have in the cold tank. You wouldn't 14 allow them to be able to control the turbine during 15 start-up or shut-down or any type of other transient 16 or any type of maintenance.
17 There would always be an override where 18 the operators have to give control to the load 19 dispatcher to be able to control the turbine. Any 20 signal that comes from the plant would override 21 anything that came from the load dispatcher. They're 22 not going to be able to control the turbine any time 23 that you don't want them to control the turbine.
24 MEMBER HALNON: Okay. Well, I think we'll 25 explore it more but again, a combination of operating NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
66 1 procedures, technical specifications, operator 2 training, and system interactions with those operators 3 pre-existing, pre-transient conditions. You have to 4 set up those conditions. It would be an interesting 5 period of discussion when we get into the operators.
6 MR. PICCARD: There would be a tech spec 7 probably for the minimal amount of salt in the cold 8 tank. Remember that's only there to allow the worst-9 case scenario runback to allow you get below five 10 percent power. Not a whole lot of heat is required 11 for that. It doesn't have anything to do with the 12 safety case.
13 MEMBER HALNON: There's no effect from the 14 Energy Island to the Nuclear Island, yet this is an 15 effect. So we have to explore that connection and how 16 that impacts the safety. Okay. I've got a clear 17 picture of where we're going. Thanks.
18 MEMBER REMPE: Just a note of procedure.
19 When you're not up front, you need to say your name 20 every time you talk for the court reporter. And you 21 probably should say it now. Thank you.
22 MR. PICCARD: That was George Piccard.
23 MR. WILLIAMS: Okay. I think we can move 24 a little quicker. The next three slides are really 25 background type of information just to show and talk NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
67 1 a little bit about that we do have a robust procedure 2 following NEI 18-04 to identify licensing basis 3 events.
4 And so the events that we've talked about 5 here would all be initiating events screening. That 6 would be looked at as part of the PRA. We're really 7 talking about those events in the green shaded region 8 here mostly today. This is a nice slide that reminds 9 us of all of the different families of events that are 10 out there being considered.
11 So the next slide shows us the defense 12 line scheme that we use on NATRiUM. I don't think 13 defense lines come directly from NEI 18-04. They're 14 more of a TerraPower methodology for being able to 15 consider defense-in-depth adequacy in the earliest 16 design phases.
17 So looking at defense lines, tracking them 18 as design requirements in our configuration management 19 of the design has really helped the safety analysts, 20 PRA people, and the engineers on the design really 21 being able to talk the same language.
22 When we look at these defense lines, we're 23 going to see a lot of the Energy Island systems, the 24 runback taking care of Defense Line 2 functions, but 25 no Defense Line 3 or 4 functions on the Energy Island.
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68 1 That's part of the independence that we have in the 2 design. The Defense Line 3 is where the safety 3 systems are. The Defense Line 4 is more of the 4 mitigation systems.
5 And then the next slide kind of shows a 6 little bit of what we were talking about there and a 7 framework for thinking about Energy Island event 8 responses versus Nuclear Island event responses and 9 how we look at deterministic safety analysis.
10 A lot of the typical events that you would 11 think of in an operating nuclear power plant that 12 happen on the balance of the plant side, those same 13 type of events on NATRiUM would really have no impact 14 on the Nuclear Island. They can't really affect the 15 Nuclear Island until an interface parameter like we 16 were talking about on the prior side gets triggered.
17 And in all cases, if the defense line 2 18 function fails, like the runback is designed to happen 19 but it doesn't happen fast enough, there's still the 20 reactor protection system set points on the Nuclear 21 Island to protect the reactor. So there's always that 22 defense line 3 protection in the plant.
23 All right. This one really talks about 24 the types of transients that we looked at. They all 25 fall into that decrease or increase in heat removal NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
69 1 from the Nuclear Island salt system.
2 And it's really the thermal inertia and 3 the intermediate heat transport system and the primary 4 heat transport system that provides the adequate time 5 to respond to the event via signals monitored within 6 the Nuclear Island.
7 So in fact, I think the deterministic 8 safety analysis will look at a pretty extreme loss of 9 heat transfer at the sodium-salt heat exchanger and 10 really use that to bound any possible thing that could 11 happen on the Energy Island, and show that the reactor 12 is designed with adequate safety margin.
13 We looked at a couple of transients in 14 detail here. The power runback, which is really 15 something that we want to perform to avoid the scram, 16 begins with reactor power being decreased by the 17 insertion of control rods at a predetermined rate.
18 And being able to do that -- there's 19 different timing that can happen with that. We're 20 designing those control rods to be able to perform 21 that runback in time to avoid the scram.
22 That involves looking at a lot of 23 different transients. Depending on how the runback 24 gets triggered, there's different time constants and 25 different interactions between the systems. We're NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
70 1 making sure that the control rods are designed in all 2 cases to avoid that scram.
3 Then the IAC and RAC provide the system 4 heat removal. These are what would normally happen in 5 the plant. We're not talking about DBA-type 6 assumptions here. We have both intermediate air 7 cooling and reactor air cooling able to provide heat 8 removal.
9 The primary sodium pump and the 10 intermediate sodium pump get decreased through their 11 targeted flow settings as part of the power runback.
12 And then finally, when you get down to about five 13 percent power, then you isolate from the Energy Island 14 using the NSS isolation valves.
15 In the case of a scram, if one of the 16 reactor protection set points gets triggered, then the 17 reactor power gets decreased. The control rod is 18 dropped by gravity, in this case, as opposed to 19 running them in on the motors.
20 The IAC and RAC also provide heat removal 21 here. The PSPOPs get ramped down. And then you 22 isolate when you get down to five percent power.
23 If we were to look at this same transient 24 from a DBA perspective, then you wouldn't take credit 25 for the intermediate air cooling. You would only take NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
71 1 credit for reactor air cooling. Instead of the PSPOPs 2 ramped down, they would be coasting down. And we 3 don't take credit for the NSSI isolation.
4 These are kind of the scenarios that were 5 included in our transient analysis that we showed the 6 staff and the different examples of each of these that 7 were presented.
8 MEMBER MARCH-LEUBA: Is only the scram 9 safety grade?
10 MR. WILLIAMS: Only scram is safety grade.
11 MEMBER MARCH-LEUBA: What are the 12 implications with ATWS? We cannot get to the reactors 13 by designing that scram very reliable. Is there more 14 than one way of getting the rods in? Do you have a 15 way to push the rods in if they don't go by gravity?
16 MR. WILLIAMS: Yes. We have a scram 17 follow function. That is also motor-driven here.
18 MEMBER MARCH-LEUBA: Is it safety grade?
19 MR. WILLIAMS: I am not sure.
20 MS. YOUNG: This is Emily Young from 21 TerraPower. The scram follow function is one of our 22 DL4 functions for our defense-in-depth. If our 23 gravity drop doesn't work for whatever reason, then 24 we'd go into that feature.
25 So it's not necessarily going to be a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
72 1 safety-related feature. It's just going to be a 2 defense-in-depth adequacy feature for us.
3 MEMBER BROWN: I thought the topical 4 report read that if you scrammed, you automatically 5 initiated the drop-in. That's the way I read it. If 6 I read it wrong, just tell me, but that's what I saw, 7 that there wasn't a differentiation.
8 MS. YOUNG: This is Emily Young. I'll 9 double check and get back.
10 MEMBER BROWN: Okay. That's the best way 11 to do it. You don't want to wait until you don't have 12 any rods.
13 MEMBER MARCH-LEUBA: The question I was 14 going to mention is to eliminate errors from your 15 analysis, you have to demonstrate that your scram is 16 on the line of 5 or whatever number you choose. So I 17 guess it's only if the components are safety grade.
18 MEMBER MARTIN: Real quick, what power 19 level does the Energy Island generate power to the 20 grid?
21 MR. WILLIAMS: You mean during start-up?
22 MEMBER MARTIN: Yes, during start-up.
23 Obviously you would have a procedure unlike what it is 24 for shutdown.
25 MR. WILLIAMS: George, our start-up NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
73 1 narrative?
2 MR. PICCARD: Yes. George Piccard, 3 TerraPower. The way the start-up narrative currently 4 reads is that we would actually put the steam 5 generators into a hot standby mode.
6 You don't need to necessarily have the 7 same type of -- get to a certain power and then roll 8 the turbine. You would have a light-water reactor 9 typically at maybe 25-30 percent power.
10 Depending on where the salt tanks were 11 whether you had a long shutdown or a short shutdown, 12 you could bring the reactor up to power, low power.
13 You could stay on the intermediate air cooling system 14 or you could put more heat into the salt tanks.
15 So there's a lot more flexibility in the 16 start-up than you would have at the light-water 17 reactor. I don't think right now we actually know 18 when is the ideal time to start rolling the turbine at 19 what power level, but I would imagine it would be 20 similar, 20 percent to 50 percent power.
21 You'd want to start putting your heat 22 somewhere. So it's just a matter of how much capacity 23 you have for where your heat goes and when you want to 24 start using it.
25 If you don't want to roll your turbine and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
74 1 you still want to bring the power up, we also have 2 steam dump valves. So there's a tremendous amount of 3 flexibility of when you actually want to start 4 generating electricity. You just don't have to do it 5 at a certain point during start-up.
6 MEMBER BROWN: Is this Nuclear Island a 7 true nuclear island? You don't even need the Energy 8 Island at all; it can support itself?
9 I thought all the electrical power that 10 was generated in the Energy Island is not self-11 supporting. Is it independent?
12 You don't have to have the grid to run the 13 plant, but you have to have the Energy Island to 14 operate the plant without electricity, but you don't 15 have any diesel generators.
16 So there's some point in here where you 17 need other power for doing something, I would think.
18 It sounds like if all the lights go out, you don't 19 care anywhere in the entire, whole plant.
20 MR. WILSON: This is George Wilson. We 21 have a diesel generator. It's not safety grade.
22 MEMBER BROWN: Okay.
23 MR. WILSON: I don't have any safety-24 related backup power.
25 MEMBER BROWN: That's fine. What I was NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
75 1 really getting to is you don't have to have the grid 2 in order to operate via a stable, low-power 3 conditioning. You're self-supporting?
4 MR. WILLIAMS: Yes. You can dump the 5 steam, I think, which is what George was saying there.
6 MEMBER BROWN: As well as run your 7 turbines, if you needed to. You could generate your 8 own electrical power from the Energy Island; is that 9 correct also?
10 MR. WILSON: This is George Wilson. We're 11 going to re-validate it if we're going to backfeed 12 from generator output back and give houseloads back 13 into what you can.
14 That is something that's still being 15 evaluated where we'll potentially backfeed in there.
16 Right now our sodium pumps would be powered from the 17 grid. So if you would lose the grid, you would lose 18 your sodium pumps.
19 MEMBER BROWN: All right. Thank you.
20 MEMBER KIRCHNER: This is Walt Kirchner.
21 Along those lines, you initially had indicated five 22 steam generator trains. Have you decided on your 23 turbine equipment yet?
24 If you had five turbines -- I'm not saying 25 that's what you're doing -- you could do a cold blast NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
76 1 start of the plant by yourself without off-site power.
2 MR. WILSON: This is George Wilson.
3 That's something that we've talked with some people 4 that are interested in our plant, actually doing a 5 backfeed and doing a cold start off of our salt tanks.
6 That's not something that we've put into the design 7 yet, but that is something we're evaluating.
8 MR. WILLIAMS: Emily, you want to add 9 something?
10 MS. YOUNG: Yes. Emily. Again, a point 11 of clarification, you are correct. The scram follow 12 would initiate immediately following a scram signal 13 generation, correct. Scram follow, yes, for freezing.
14 And then also there was a question about 15 unprotected events. I just want to make a point of 16 clarification that we do have some unprotected events 17 that we are looking at for the LMP process in terms of 18 discussing the cliff edge effect, but those are 19 currently screened out of our BDBE region.
20 Their frequency is what we're clarifying 21 as an OQE, an other quantified event. So we will look 22 at those.
23 But the scram follow events where we don't 24 have gravity drop and motor drive-in, those events are 25 categorized as a beyond-design-basis event per the LMP NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
77 1 currently. So they will be on our list of assessed 2 events in our LBE list.
3 MR. WILLIAMS: Thanks, Emily.
4 All right. I'll turn this over to you, 5 George.
6 MR. WILSON: My name is George Wilson.
7 I'm going to talk about what I call the interface or 8 the separation between the Energy Island and Nuclear 9 Island, the potential regulations that wouldn't fully 10 apply to our design.
11 The first thing we have to look at is the 12 NRC's definition in 10 CFR 50.2 of what safety-related 13 means. And then we look at what the NEI 18-04 14 difference in safety-related, their definition.
15 The NEI's is actually based on function 16 and frequency. The NRC's is to do with boundary and 17 has three criteria. Right now we need to either show 18 how we're going to meet the intent of 50.2 or take an 19 exemption of 50.2 and use the classification and the 20 definition and NEI 18-04 for our definition of safety-21 related.
22 I'll focus on the bottom two first. For 23 10 CFR 55, licensed operator reaction, if you look 24 into the guidelines and the definitions in 10 CFR 55, 25 this is one of the actions. We require an operator to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
78 1 have a license.
2 The scope of 55.2 says any individual who 3 manipulates the controls of any utilization facility 4 licensed under 50.52 and 54 of this chapter. The key 5 word there is control 6 When you go into the definitions in 10 CFR 7 50.54, the definition is controls when used with 8 respect to a nuclear reactor means an apparatus and 9 mechanism, the manipulation of which directly affects 10 the reactivity or power level of the reactor based on 11 the fact of the inertia that you can operate the 12 turban.
13 It has to go through the salt tanks and 14 then it has to go through the intermediate heat 15 transfer system. Finally, it gets to the primary heat 16 transfer system. The time lapse that it takes, there 17 is no direct reaction between operating the turbine 18 and the impact of the reactor.
19 It can be minutes or even hours before you 20 would see an impact back onto the reactor power based 21 on where you were at. So with that, it is our 22 intention to allow the turbine generator to be 23 operated by the grid operator just like they would in 24 a fossil fuel plant.
25 MEMBER MARCH-LEUBA: When you say grid NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
79 1 operator, do you mean somebody located in Atlanta?
2 MR. WILSON: Well, it would be someone 3 located in the grid operations of --
4 MEMBER MARCH-LEUBA: Remotely?
5 MR. WILSON: Remotely, right. It would 6 just be operated remotely. Our turbine will be 7 designed with a different ramp rate. Our plant can 8 truly load follow because there is no -- you operate 9 the turbine and reactor at a different power level.
10 So it is our intentions with our design to 11 allow our turbine to be operated remotely. There will 12 be constant communication with our control room and 13 our operators, but it would be the intention to allow 14 our turbine to be operated.
15 MEMBER MARCH-LEUBA: And of course, this 16 is a plant that will be doing the safety analysis 17 because all you do is get bored of the computer with 18 numbers. You could consider cybersecurity, attacks, 19 and all this kind of stuff -- you have to make sure 20 that the Energy Island truly does not feed back into 21 the nuclear?
22 MR. WILSON: Right. We have to have air 23 gaps. We will meet the NRC's requirement. NEI will 24 be doing the cybersecurity. We'll also have to meet 25 the requirements of the CIP standards because there is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
80 1 a bright line between when FERC standards roll over 2 and it's the first isolation point after the turbine.
3 So we'll have to meet all the requirements 4 for cybersecurity and physical security. We've had to 5 look at allowing to reach out to the grid operator to 6 do the turbine. It will be something new for the NRC.
7 We've already bridged that with --
8 MEMBER MARCH-LEUBA: You're completely 9 opening the firewall to the grid operator?
10 MR. WILSON: To a certain extent. I'm not 11 going to go into that.
12 MEMBER BROWN: To a lesser extent unless 13 you open the LAN.
14 MEMBER BALLINGER: This is Ron Ballinger.
15 When you say control power remotely, will you be 16 allowing people to remote control other 17 characteristics like reactor power? Can you do that?
18 MR. WILSON: I just know right now we 19 would allow the -- I don't know about decay bars. Is 20 that what you're talking about, reactor power?
21 MEMBER BALLINGER: Yes.
22 MR. WILSON: We're still working with 23 PacifiCorps on what we're going to do, but there would 24 be no issue with them changing. You're just changing 25 the output of your turbine that you're putting into NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
81 1 the grid. If I'm putting a reactive load out, I would 2 have to maintain reliability.
3 We're still working those details out with 4 who would be our grid operator of PacifiCorp. That 5 would be our intention to allow them to. There will 6 be direct communications all the time, but that's 7 something that the industry is actually very 8 interested in.
9 MEMBER HALNON: So in the spirit of 10 helping move along, this has been done for 50 years.
11 The case is that they're saying it doesn't affect the 12 reactor.
13 If it doesn't affect the reactor and it 14 doesn't affect reactor safety, then what the grid 15 operator does is independent of all that. The certain 16 extent is within the limits we've already talked 17 about.
18 MEMBER MARCH-LEUBA: The problem, Greg, is 19 the US is a juicy target for the bad guys. If a 20 hacker in North Korea gets control of your Energy 21 Island, it's not a safety concern, but you'd make it 22 to CNN. And you will have to go testify in front of 23 Congress.
24 MEMBER HALNON: I think we can argue that 25 point as well. I don't think it's that juicy of a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
82 1 target, but go on.
2 MR. SCHULTZ: Steve Schultz, just a 3 question. I understand the turbine operation issue 4 associated with operator licensing. The other 5 elements associated with the Energy Island, are those 6 functions for the tanks and so forth performed by a 7 licensed operator?
8 MR. WILSON: Right now we're still 9 developing our reactivity manipulations control 10 program. If you look at the NRC's conditions, it said 11 we didn't look at 54(j). We will have definitions.
12 We'll have that just like any other reactor.
13 You have to have a reactivity 14 manipulations control program and start looking at the 15 indirect impacts and what would have to be controlled 16 by a licensed operator or overseen by the operator.
17 So we're still fully evaluating that.
18 But right now, if there would be, it would 19 be some of the stuff with the salt tanks and nothing 20 with the rest of the plant on the Energy Island side.
21 We're still looking at that. We haven't fully 22 developed that. That's one of the conditions the NRC 23 has put in our top drawer.
24 MEMBER HALNON: Understood. Thank you.
25 MR. WILSON: When we looked at 10 CFR NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
83 1 Appendix B, Appendix B states that this appendix 2 applies to all activities affecting the safety-related 3 functions of those structure systems and components.
4 During our classifications of the way that 5 we do the SSCs, based on when we do the licensing 6 basis events, currently there is no safety-related or 7 non-safety related with special treatment systems, 8 structures, or components located on the Energy 9 Island.
10 Therefore, on the classification -- you 11 heard the NRC staff; they'll talk about it a little 12 bit more -- their Appendix B would not apply to 13 anything on the Energy Island. The other two 14 regulations are kind of lumped together.
15 One of them would be a limited work 16 authorization of 10 CFR 50.10 and 10 CFR 50.65.
17 Requirements for monitoring effectiveness of the 18 maintenance at power plants, known as the maintenance 19 rule. 10 CFR 50.10 and 50.65 have the same language 20 in there. So 50.10 actually borrows the maintenance 21 rule language for some of the criteria.
22 When we looked at the maintenance rule 23 language specifically, we focused on (b)(2). It says 24 non-safety related structures, systems, or components.
25 It you look at item number 3, it says whose failure NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
84 1 could cause a reactor scram or actuation of a safety-2 related system.
3 To get additional clarification for that, 4 the NRC's Reg Guide 1160, which actually references 5 the NUMARC 93-01 standard -- and if you go into the 6 NUMARC 93-01 standard, item number 3, which is more 7 clarity to the regulations, states systems, 8 structures, and components identified in the 9 licensee's analysis whose failure would cause a 10 reactor scram or actuation of a safety-related system.
11 Based on that clarification, the salt system could 12 cause a reactor scram if a runback did not happen.
13 So we said that it meets that criteria of 14 the maintenance rule. It is our intention based on 15 using the LMP process to go after an exemption of this 16 based on our risk-informed performance-based approach 17 because, as I stated earlier, there's no safety-18 related or non-safety related with special treatment 19 systems in the Energy Island.
20 So really, the intent of the maintenance 21 rule was to keep those systems robust so that you made 22 sure you can do your safety system. So it is our 23 intention to go after an exemption of 10 CFR 50.65 24 just for that criteria and have those systems, 25 structures, and components in the Energy Island of the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
85 1 maintenance rule.
2 That's all I have. If there's no 3 questions, thank you guys for your time. We greatly 4 appreciate your time. We're here if you have any 5 other questions.
6 MEMBER MARCH-LEUBA: Out of curiosity, 7 could you tell us something of your schedule? What 8 are your plans?
9 MR. WILSON: The plan is we'll be 10 submitting our construction permit application in 11 March of 2024 for the NRC to review.
12 MEMBER MARCH-LEUBA: Your vision is to be 13 operating the plant when?
14 MR. WILSON: We'll start preconstruction 15 activities the first quarter of '25. Full operations 16 -- Nick, you can help me here -- I think it's 2030.
17 MEMBER MARCH-LEUBA: Thanks.
18 CHAIR ROBERTS: It's Tom Roberts. It's 19 now 10:05. We're about 25 minutes behind schedule.
20 To help that along, I figure we'd take about a ten-21 minute break. Looking around, I think there's 22 agreement to do that.
23 I think we have enough time towards the 24 end of the schedule here to make up the time. We'll 25 reconvene at about 10:15 this morning. We'll go with NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
86 1 the NRC staff and then proceed from there.
2 (Whereupon, the above-entitled matter went 3 off the record at 10:06 a.m. and resumed at 10:16 4 a.m.)
5 CHAIR ROBERTS: It is now 10:15 and we're 6 coming back into session. We now have the NRC staff 7 presentation. Candace de Messieres will start the 8 presentation for the staff.
9 MS. DE MESSIERES: Thank you, Chairman 10 Rempe and Member Roberts, for the opportunity to 11 present to the committee today. I am Candace de 12 Messieres, Chief of Advanced Reactor Technical Branch 13 2 in the Division of Advanced Reactors and Non-Power 14 Production and Utilization Facilities, or DANU, in the 15 Office of Nuclear Reactor Regulation.
16 During this meeting, the NRC staff will 17 provide you with a summary of our review of 18 TerraPower's topical report titled Regulatory 19 Management of NATRiUM Nuclear Island and Energy Island 20 Design Interfaces.
21 As we've been discussing, this topical 22 report pertains to the decoupling strategy to ensure 23 independence of operation between nuclear and Energy 24 Island systems for the NATRiUM design.
25 The topical report contains TerraPower's NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
87 1 evaluation for regulations and requests NRC approval 2 of the topical report such that the NATRiUM reactor 3 licensees can utilize the regulatory evaluation via 4 reference and licensing submittals.
5 I'll emphasize that this review is part of 6 ongoing pre-application engagement with TerraPower.
7 Our review conclusions rely on key preliminary design 8 and analysis aspects and assumptions.
9 These aspects and assumptions, which 10 include implementation of key design features and 11 assignment of SSC safety classifications, will be 12 confirmed as part of future licensing reviews and are 13 reflected in our topical report safety evaluation in 14 the form of limitations and conditions.
15 I will now turn it over to the NATRiUM 16 Project Management and Technical Leads, Mallecia 17 Sutton, Senior Project Manager, and Reed Anzalone, 18 Senior Nuclear Engineer, as well as Jesse Seymour, 19 Senior Reactor Engineer Examiner, to present details 20 of our review.
21 Thank you again for the opportunity to 22 present to the committee. We look forward to your 23 observations and feedback.
24 MS. SUTTON: Good morning. I'm Mallecia 25 Sutton. I'm glad to be here with you guys. Let me go NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
88 1 to the next slide, please.
2 I'll provide a review of the time line of 3 this topical report. We had a pre-engagement 4 application public meeting on November 17th of 2021 to 5 discuss the potential of submittal. The initial 6 submittal was a white paper titled Energy Island 7 Decoupling Strategy, which was submitted on February 8 4th.
9 At the staff review, we had another 10 discussion with TerraPower where they voluntarily 11 withdrew the submittal because we didn't have 12 sufficient information to conduct a review.
13 After further discussion, TerraPower 14 decided to submit its topical report, why we're here 15 today, titled Regulatory Management at NATRiUM Nuclear 16 Island on October 4th of 2022. Staff accepted the 17 topical report on November 16th.
18 We conducted an audit to understand the 19 transient analysis discussed in topical report to 20 demonstrate compliance with 10 CFR 50.54(j). The 21 staff will discuss more detail. The audit ran from 22 January 23, 2023 to March 10, 2023. Then staff 23 finalized the draft safety evaluation report, which 24 was issued on August 10, 2023.
25 With that, I'll turn it over to Reed to go NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
89 1 over the staff's evaluation of the topical report.
2 Thank you.
3 MR. ANZALONE: Thanks, Mallecia. I think 4 I can tell the microphone is working, which is always 5 a concern for me.
6 I think TerraPower did a pretty good job 7 of going over the purpose of the topical report. I'm 8 not going to talk about that anymore. I'll just focus 9 on our strategy for the review.
10 What we wanted to do in this review, given 11 where we are in the design and licensing design 12 process with TerraPower, what we wanted to focus on 13 was those key aspects of the NATRiUM design and 14 analysis presented in the topical report, and kind of 15 use that as the context for the regulatory evaluations 16 that they were doing. And then propose appropriate 17 limitations and conditions that would be necessary for 18 those evaluations to be acceptable.
19 And really, that's kind of the structure 20 of this presentation too. We're going to talk about 21 the key aspects of the design and analysis. We're 22 going to look at the regulatory evaluations, and then 23 we're going to talk about the limitations and 24 conditions.
25 Next slide. I say basically the same NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
90 1 thing on this slide. Next slide, please.
2 So I also have a little design overview 3 that I put together that I think goes along with what 4 TerraPower did. We can walk through this pretty 5 quickly.
6 These figures are taken from the topical 7 report. There's the primary heat transport system.
8 There's the intermediate loop going between the 9 intermediate heat exchanger and the sodium-salt heat 10 exchanger.
11 There's the thermal salt storage system 12 with the hot and cold salt tanks. And the separation 13 between the Nuclear Island and Energy Island is those 14 isolation valves there on the thermal salt storage 15 system.
16 Also on the Energy Island there's the 17 steam generating system. Those are the same diagrams 18 that TerraPower presented earlier.
19 Keep going.
20 So on the Nuclear Island, we've got these 21 safety systems, the reactor air cooling system, and 22 the intermediate air cooling system. The one thing I 23 wanted to talk a little bit more about on this slide 24 was the audit, which TerraPower touched on a little 25 bit, what they shared with us. I wanted to just NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
91 1 mention the key audit findings.
2 We looked at the analysis that they 3 performed concerning the Energy Island/Nuclear Island 4 interface and the ability of the Nuclear Island to 5 respond to transients on its own. Those Energy Island 6 events -- and TerraPower mentioned this -- that have 7 the greatest possibility to affect the Nuclear Island 8 are the ones that occur physically closest to the 9 Nuclear Island.
10 Events that occur further out from that 11 interface can really all still be boiled down to 12 changes at the Nuclear Island/Energy Island interface.
13 The question is just how long does it take for those 14 changes to propagate through.
15 Even then, once you have those changes 16 that you see at the Nuclear Island/Energy Island 17 interface, how long does it take those to propagate 18 through to where they have an effect on the core?
19 TerraPower talked a bit about the thermal 20 inertia of the various systems. We see that those are 21 really significant towards making the case for Energy 22 Island/Nuclear Island independence.
23 The design of the primary heat transport 24 system, the fact that they're using a pool-type SFR, 25 the intermediate heat transport system and how big it NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
92 1 is. And then the really big thing is the thermal salt 2 storage system, which pretty much effectively 3 insulates changes in turbine power from affecting 4 reactor power, as we've discussed.
5 Next slide.
6 MR. SCHULTZ: Reed, before you go on, this 7 is Steve Schultz.
8 MR. ANZALONE: Sure.
9 MR. SCHULTZ: I meant to ask TerraPower 10 about this. You talked about the time frames that are 11 available for the interaction between the Energy 12 Island and the Nuclear Island qualitatively. Can you 13 quantify that a bit, the power and so forth?
14 MR. ANZALONE: It really depends on the 15 specific transient, what's going on, and what system 16 you're talking about. But it is minutes to hours, not 17 seconds. I think that's pretty much the only level I 18 can -- it really depends on the particular --
19 MR. SCHULTZ: That's fine. I wanted to 20 get the minutes and the powers on the record. Thank 21 you.
22 MR. ANZALONE: Okay. I think George 23 mentioned that during the last little bit of --
24 MR. SCHULTZ: Thank you.
25 MR. ANZALONE: So I'm going to touch on NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
93 1 the safety classification using NEI 18-04, which is 2 the risk-informed, performance-based technology 3 inclusive guidance for non-light-water reactor 4 licensing basis development. That's a mouthful so I'm 5 just going to say NEI 18-04 LMP from now on.
6 We endorsed that in Reg Guide 1.233.
7 TerraPower is following those approaches as endorsed 8 in the Reg Guide.
9 It's a risk-informed, performance-based 10 safety classification approach that's laid out in NEI 11 18-04, which is highly integrated with other aspects 12 of the process including the selection and analysis of 13 licensing basis events and evaluation of adequacy. I 14 think TerraPower later in the presentation showed some 15 of those pieces all together.
16 It's a slightly different definition for 17 safety-related SSCs than in 50.2, which George touched 18 on. The 50.2 definition talks about safety-related 19 SSCs should be those needed to ensure the integrity of 20 the reactor coolant pressure boundary, the capability 21 to shut down the reactor and maintain it in a safe 22 shutdown condition, or the ability to prevent or 23 mitigate the consequences of accidents which could 24 result in off-site releases comparable to the 50.34 25 limits.
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94 1 We think that conceivably you could use 2 the LMP process to demonstrate compliance with that 3 50.2 definition of safety-related, but you may or may 4 not. So you might need to take an exemption from 5 50.2. I think TerraPower is considering that as well.
6 Go to the next slide, please, Candace.
7 CHAIR ROBERTS: Reed, Tom Roberts. I'm 8 just trying to understand some examples of what might 9 not meet the definition of 50.2, if it were shown to 10 be safety-related per LMP.
11 MR. ANZALONE: I think there's a question 12 of whether what TerraPower has in their reactor design 13 constitutes a reactor coolant pressure boundary, 14 quote/unquote, because it's operating at atmospheric 15 pressure.
16 They have made a distinction historically 17 between reactor coolant boundary versus reactor 18 coolant pressure boundary. Other more exotic designs 19 might deviate a little bit even further away from 20 those definitions in 50.2.
21 So NEI 18-04 and our Reg Guide kind of 22 leaves open the possibility that you might need an 23 exemption from 50.2. Does that answer the question?
24 CHAIR ROBERTS: I think so. Is that the 25 case here? It seems like integrity of the coolant NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
95 1 boundary is going to be required regardless of what 2 you call it.
3 MR. ANZALONE: Yes. It's just a matter of 4 wording. I think they would propose an alternate 5 definition. I believe there was a public meeting we 6 had with them some time last year where they talked 7 about changing that to just say reactor coolant 8 boundary or primary coolant boundary instead of 9 reactor coolant pressure boundary.
10 CHAIR ROBERTS: It gets into more 11 semantics than technical? That's what I'm trying to 12 understand.
13 MR. ANZALONE: Yes. I would agree with 14 that.
15 CHAIR ROBERTS: Okay. Thank you.
16 MR. ANZALONE: So the NEI 18-04 process 17 uses this definition for the different safety 18 classifications that are available. There's the 19 safety-related SSCs and those are the SSCs selected 20 for the required safety functions to mitigate design-21 basis events within the frequency consequence target 22 curve. I have a slide coming up where I'm going to 23 explain what that actually means.
24 And SSCs selected for required safety 25 functions to prevent high consequence beyond design-NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
96 1 basis events from entering the design-basis event 2 region beyond the frequency consequence target. I'll 3 talk about those more when we get to the next slide.
4 There's also this concept of non-safety 5 related with special treatment, which is roughly 6 analogous to Part 50. Those are the non-safety 7 related SSCs that are performing risk significant 8 functions or needed for defense-in-depth.
9 I think that conceptually you can think 10 about you might have multiple SSCs that can do a 11 safety function. You would have one you would 12 designate as safety-related and then you would have 13 another that you would designate potentially as non-14 safety related with special treatment.
15 And then the final category is non-safety 16 related with no special treatment, which as TerraPower 17 has discussed, they're trying to get all those Energy 18 Island SSCs to be in that final category.
19 Next slide, please, Candace.
20 Here's the frequency consequence target 21 curve from NEI 18-04. I'm just going to use this to 22 try to help explain those safety-related SSCs.
23 If you can advance it a little bit, that's 24 the design-basis event region, which is those events 25 that have a frequency between 1E minus 4 and 1E minus NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
97 1 2. The high consequence beyond design-basis events 2 are those in the beyond-design basis event region.
3 So that's between five times ten to the 4 minus seventh and ten to the minus fourth. Those are 5 beyond the 50.34 dose limit. The safety-related SSCs 6 are used to keep the DBEs within the frequency 7 consequence target. The high-consequence BDDE is 8 within the frequency consequence target.
9 Also -- if you can advance it one more 10 time, Candace -- only the safety-related SSCs are 11 available to keep design-basis accidents below the 10 12 CFR 50.34 dose limit.
13 Those design-basis accidents are DBE 14 events that have been stylized to use very 15 conservative assumptions. There's a deterministic 16 analysis that's done to show that they stay below the 17 50.34 limit using only safety-related SSCs.
18 MEMBER MARTIN: This is Bob Martin. Is 19 their power showing preliminary results for dose 20 consequences --
21 MR. ANZALONE: Yes.
22 MEMBER MARTIN: -- and their methodology?
23 Is there a slide, maybe somewhere else because it's 24 not here, of how they compare to the curve?
25 MR. ANZALONE: There are some results NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
98 1 from, I want to say, earlier this year. Those were at 2 the time considered proprietary.
3 MEMBER MARTIN: We're okay seeing that, 4 right?
5 MR. ANZALONE: Yes since this is a public 6 meeting. Yes, everything was inside the target curve.
7 MEMBER MARTIN: They submitted a topical 8 on those consequences and methodology?
9 MR. ANZALONE: They will be submitting a 10 topical and on the deterministic safety analysis. The 11 safety classification process was one of the key 12 things that we were considering in our review of the 13 topical report in addition to the design.
14 So now I'll talk a little bit about the 15 regulations that were covered in the topical. I think 16 George actually did a great job overviewing these 17 during TerraPower's presentation.
18 They looked at 50.10 and 50.65, which are 19 the LWA rule and the maintenance rule which, as he 20 said, have identical requirements for some of them.
21 They looked at Appendix B and Part 55.
22 Next slide.
23 The LWA rule provides a requirement that 24 no person may begin the construction of a production 25 or utilization facility on a site on which the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
99 1 facility is to be operated until they've been either 2 issued a construction permit or a limited work 3 authorization.
4 50.10(a)(1) provides the scoping criteria 5 that defined what constitutes construction in the 6 context of the rule. Those scoping criteria were 7 chosen to encompass those SSCs that have a reasonable 8 nexus to radiological health and safety or common 9 defense and security.
10 If you go to the next slide, Candace.
11 Criteria 2, 3, and 4 were chosen based on 12 the language in the maintenance rule, which had 13 already been around for some time at this point.
14 Basically, when the Commission was promulgating the 15 LWA rule, there was a desire to try to use agreed-upon 16 definitions for what had a reasonable nexus to health 17 and safety.
18 They just basically lifted those criteria 19 from the maintenance rule because there was guidance 20 and they had been used for some time. Then also, 21 criteria 1 is safety-related SSCs.
22 And then there are several additional 23 criteria. Those necessary to comply with Part 73, 24 which is the security regulations, those needed to 25 comply with 50.48 and criteria 3 of the general design NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
100 1 criteria, which are fire protection regulations and 2 those needed for on-site emergency facilities.
3 If you could go to the next slide?
4 MR. MARCH-LEUBA: Not allowing testing?
5 You have testing at the end of the first paragraph.
6 MR. ANZALONE: I have to say I don't 7 actually know off the top of my head.
8 MR. MARCH-LEUBA: I think if they come and 9 ask you that you would tell them, yes, go ahead and 10 test all you want. Okay.
11 MR. ANZALONE: So I'm going to walk 12 through all the criteria in 50.10(a)(1). First I'll 13 talk about TerraPower's evaluation and then I'll talk 14 about what we thought about that evaluation.
15 So criteria 1 they said wasn't applicable 16 because those Energy Island SSCs are non-safety 17 related with no special treatment. We said that was 18 reasonable.
19 It's consistent with the NEI 18-04 safety 20 classification definition, but we did have a 21 limitation regarding the definition of safety-related.
22 I've already talked about how there's a distinction 23 between the 50.2 definition and the NEI 18-04 24 definition.
25 Criteria 1 here actually specifically NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
101 1 refers back to 50.2. Rather than saying safety-2 related, it says safety-related SSCs as defined in 10 3 CFR 50.2.
4 So if it just said safety-related, it 5 wouldn't necessarily be an issue. But if they're 6 getting an exemption from 50.2, they would also need 7 to get an exemption here. And that's what the 8 limitation tries to make clear.
9 Criteria 2 TerraPower determined wasn't 10 applicable because Energy Island SSCs aren't used to 11 mitigate accidents or transients or used in the EOPs, 12 the emergency operating procedures. We thought that 13 was consistent with the plant design.
14 We wouldn't expect non-safety related SSCs 15 to participate in mitigation or prevention of 16 accidents or transients, but we haven't reviewed 17 TerraPower's emergency operating procedures. They're 18 still under development. So we added a limitation and 19 condition on the topical report to address that.
20 Criteria 3 isn't applicable because the 21 NSD SSCs wouldn't be capable of preventing safety-22 related SSCs from fulfilling their safety functions.
23 We thought this was consistent with the NEI 18-04 24 safety classification definition. And I'll also note 25 I think I have a slide that talks a little bit more NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
102 1 about this later.
2 There was a comment or a staff position in 3 the Reg Guide endorsing NEI 18-04 that says basically, 4 if an SSC provides a central support to a higher 5 classified SSC, so if you had an SSC providing support 6 to a safety-related or non-safety related with special 7 treatment SSC, we would expect that support in SSC to 8 be classified the same as the higher classification 9 SSC.
10 And finally, on this slide criteria 4, and 11 George talked about this, they determined that it was 12 applicable because the failure of an Energy Island SSC 13 could eventually cause a reactor trip and they planned 14 to seek an exemption. And that they would use the 15 same exemption basis for 50.10(a)(1)(4) and 16 50.65(b)(2)(3) because those are the same language.
17 We agreed with TerraPower's determination 18 that the criteria was applicable. We thought it was 19 reasonable to use the same exemption basis for the two 20 regulations that have the same language, but we didn't 21 take a position on the prospective exemption. We'll 22 review that when we get it.
23 Next slide.
24 Criteria 5 TerraPower said wasn't 25 applicable because there wouldn't be any physical NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
103 1 security program SSCs on the Energy Island. And that 2 if they had any SSCs that were identified as critical 3 digital assets for the cybersecurity program, they 4 wouldn't be installed on the Energy Island prior to 5 the construction permit.
6 We felt like that was consistent with the 7 design, but we kind of expect that that would be 8 constrained in scope to the Nuclear Island. We didn't 9 have a lot of detail on the security program. We're 10 going to have to look at those further when we have 11 those details.
12 Criteria 6 they judged to be non-13 applicable because fires on Energy Island would not 14 prevent the ability to maintain and achieve shutdown, 15 which is really the focus of 50.48. We thought that 16 that was an adequate evaluation because those Energy 17 Island SSCs are non-safety related with no special 18 treatment, as TerraPower talked about quite a bit 19 today, and can be achieved and maintained solely using 20 Nuclear Island systems.
21 And then finally, criterion 8 they 22 determined was not applicable because the on-site 23 emergency facilities would not be located on the 24 Energy Island. We felt like that was consistent with 25 the plant design and could be a design goal, but we NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
104 1 hadn't seen that flushed out yet to the point where we 2 could say definitively yes. The on-site emergency 3 facilities are not on the Energy Island. So we had a 4 limitation condition there.
5 Next slide.
6 MEMBER HALNON: So the end result of all 7 of this was this evaluation in combination with the 8 limits and precautions, limits and conditions, and 9 their exemptions? They can build Energy Island 10 without a limited work authorization?
11 MR. ANZALONE: If it appears it's going in 12 that direction.
13 MEMBER HALNON: Okay. So this is a hurdle 14 that they jumped over, and it looks like there's a 15 clear road ahead but there's still some --
16 MR. ANZALONE: Yes. I would agree with 17 that.
18 So I'll talk a little bit about the 19 maintenance rule but really, fundamentally the 20 evaluation was basically the same as for 50.10. The 21 maintenance rule requires licensees to have a program 22 that monitors the performance or condition of certain 23 SSCs or demonstrates that they'll be able to perform 24 their intended functions through appropriate 25 preventative maintenance.
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105 1 The scope of the SSCs are basically the 2 same as the several regulations that we already talked 3 about in 50.10. 50.65(b)(1) is similar to but not 4 identical to 50.10(a)(1)(i) in that it doesn't say 5 safety-related SSCs as defined in 50.2. It says 6 safety-related SSCs to include all of the stuff that's 7 in the definition in 50.2, so it's a little bit 8 different there, but then the other criteria in 50.65 9 are the same as the ones in 50.10.
10 Next slide.
11 So TerraPower didn't evaluate 50.65(b)(1),
12 which is the note about safety-related, so we didn't 13 disposition that in our safety evaluation. The other 14 criteria we evaluated the same as in our evaluation 15 under 50.10.
16 Next slide.
17 Appendix B provides quality assurance 18 requirements for the design, manufacture, and 19 construction of certain SCCs, and it applies to all 20 activity is affecting the safety-related functions of 21 SSCs that prevent or mitigate the consequences of 22 postulated accidents that could cause undue risk for 23 the health and safety of the public.
24 Next slide.
25 So TerraPower asserted that all the Energy NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
106 1 Island SSCs will be non-safety related with no special 2 treatment, and that SSCs classified as non-safety 3 related with no special treatment under that NEI 18-04 4 process wouldn't be capable of affecting the safety-5 related function of the SSCs used for prevention or 6 mitigation.
7 We considered the role that we would 8 expect non-safety related SSCs to play, and determined 9 that the evaluation was acceptable. That's the staff 10 position that I mentioned earlier, that support SSCs 11 should be classified at the higher level of the SSCs 12 that they support.
13 Now I'm going to turn it over to Jesse --
14 MEMBER MARCH-LEUBA: Hold on.
15 MR. ANZALONE: Sure.
16 MEMBER MARCH-LEUBA: Let me just make a 17 comment. This is not a criticism. Appendix B is 18 good. Appendix B is also painful and expensive to be 19 brought in.
20 From a public presentation point of view, 21 they don't need to do any QA on the Energy Island.
22 I'm sure TerraPower is going to do some ISS standard 23 or something like that.
24 So from a public presentation point of 25 view, we should say that the QA that they're planning NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
107 1 to do is sufficient and doesn't need to be expanded to 2 the Appendix B's standards. I'm just suggesting that 3 because I'm sure you're going to use QA. It's an 4 expensive plant.
5 MR. ANZALONE: Point taken. Thank you.
6 MEMBER HALNON: The QA is going to be 7 essentially -- it's required by the construction 8 codes, right?
9 MR. ANZALONE: Which is not nothing.
10 MEMBER HALNON: No. You've got all kinds 11 of steps on there.
12 MR. ANZALONE: All right. Now Jesse is 13 going to talk a little bit about Part 55.
14 MR. SEYMOUR: Thank you, Reed.
15 My name is Jesse Seymour. I'm an operator 16 licensing examiner and technical reviewer at NRR. I 17 reviewed the Part 55 related portion of the topical 18 report.
19 In the topical report, TerraPower 20 describes that the NATRiUM design removes direct 21 interaction between the reactor and the turbine 22 generator, which results in operation of the turbine 23 generator not constituting an apparatus or mechanism.
24 This manipulation directly affects the reactivity or 25 power level of the reactor.
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108 1 TerraPower also states in the topical 2 report that NATRiUM design would allow for a non-3 licensed operator based upon that to operate the 4 turbine generator. From an operator licensing 5 perspective, this is much different than the current 6 large light-water reactor practice in which turbine 7 generator operations have historically been considered 8 to be control manipulations, and therefore restricted 9 to being only performed by licensed operators.
10 In evaluating TerraPower's position, a key 11 consideration is TerraPower's description of the 12 NATRiUM thermal storage system as providing a 13 significant thermal energy storage capacity that can 14 be used to support electrical generation such that the 15 reactor power wouldn't be directly correlated to 16 turbine manipulations.
17 MEMBER HALNON: Jesse, did you look at 18 this from just the turbine generator set or for the 19 whole Energy Island perspective?
20 MR. SEYMOUR: I'll address the Energy 21 Island aspect a little further into this. The primary 22 consideration was who could operate the turbine. So 23 again, when you're looking at the Energy Island, 24 obviously there's other things that could potentially 25 be seen coming off the system, drawing salt energy.
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109 1 MR. HALNON: Levels of the salt tanks was 2 what I was -- it seems like the closest connection to 3 effects on the Nuclear Island. That's what I was 4 curious about, whether or not we're talking about an 5 exemption for the entire Energy Island or just what 6 you have to run the turbine with.
7 MR. SEYMOUR: So the focus of topical 8 evaluation is going to be on the turbine generator 9 operation itself and whether the turbine constitutes 10 a control. When we get to the broader discussion of 11 the Energy Island, that's covered more so by the 12 50.54(j) discussion I'll be going through later on.
13 MR. HALNON: Okay.
14 MR. SEYMOUR: One thing I do want to throw 15 in there is this is part of the reason that we wanted 16 to judge the exemptions on their own merits when those 17 come in. Those will more, we would expect, very 18 clearly define the scope of what would be exempt and 19 what wouldn't.
20 We evaluated these considerations within 21 the context of the regulations of 10 CFR Parts 50 and 22 55, the associated regulatory history, and the 23 relevant statutory requirements. As I'll discuss in 24 detail in the next slide, the word direct is used in 25 the definition of control is central to understanding NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
110 1 the meaning of key regulations involved here and 2 evaluating the assessment of the topical report.
3 Next slide, please.
4 The Atomic Energy Act defines operators 5 under Section 11 as being individuals who manipulate 6 the controls of utilization facilities. The Atomic 7 Energy Act also mandates under Section 107 that 8 individuals who operate utilization facility controls 9 must be licensed by the NRC.
10 Thus, there is a statutory driver behind 11 why only licensed operators will operate the controls 12 of the facility. Very importantly, though, the Atomic 13 Energy Act does not define what those controls 14 actually consist of, which leaves that definition to 15 instead be made by the NRC via regulation.
16 From the inception of operator licenses 17 back in 1956, manipulation of the controls of the 18 utilization facility has been restricted to licensed 19 operators under the Regulation 50.54(i). That 20 specific regulation is very closely linked to the 21 Atomic Energy Act provisions that I discussed.
22 It's worth noting that the original 1956 23 definition of controls was much broader than the 24 modern version and formally encompassed mechanisms 25 which by manipulation or failure to manipulate singly NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
111 1 or in combination could result in the release of 2 atomic energy or reactor materials in amounts 3 determined by the Commission to be sufficient to cause 4 danger to the health and safety of the public. So 5 again a very, very broad definition in its original 6 form.
7 In 1963, the Atomic Energy Commission 8 narrowed that definition significantly on the basis 9 that a regularly narrow interpretation of what was 10 truly controlled would be more consistent with the 11 Commission's original intent.
12 An amended definition of controls remains 13 unchanged in its present day and is limited to the 14 scope of apparatus and mechanisms, the manipulation of 15 which directly affects the reactivity or power level 16 of the reactor.
17 Separately, 50.54(j) was also introduced 18 in 1963, which also addresses the manipulation of 19 apparatus and mechanisms other than the controls, the 20 operation of which may affect the reactivity or power 21 level of a reactor and states that those shall be 22 manipulated only with the knowledge and consent of a 23 licensed operator present at the controls.
24 Notably, those types of operations are 25 permitted to be conducted by individuals other than NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
112 1 licensed operators provided that the provisions or 2 consent and oversight are still met.
3 The key takeaway here is that the 4 regulations recognize the distinctions between an 5 apparatus or mechanism, whose manipulation directly 6 affects the reactivity or power level of the reactor, 7 and those that are not direct in nature, with separate 8 requirements governing each of those.
9 As mentioned earlier, the word direct and 10 the definition of controls is the key here. The 11 implication of the use of the word direct was that 12 controls can be interpreted to mean apparatus and 13 mechanisms that when manipulated affect reactor power 14 level reactivity without also needing something 15 intermediate to make that happen.
16 Manipulations of that type fall under the 17 scope of 50.54(i) and their performance is going to be 18 restricted to licensed operators and senior operators.
19 Again, there's a very direct tie back to the Atomic 20 Energy Act on that.
21 Thus the presence or absence of a 22 significant intermediary between any given 23 manipulation and the reactivity or power level effects 24 on the reactor is the key factor that we as a staff in 25 our judgement identified as being the essential NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
113 1 determinant of whether given operations fall under the 2 scope of 50.54(i).
3 Based upon that perspective, we evaluated 4 the implications of NATRiUM's described design and 5 determined that the thermal storage system would act 6 as a significant intermediary between manipulations 7 involving Energy Island steam loads and reactivity 8 effects on the reactor.
9 This led to our conclusion in the safety 10 evaluation. Manipulations of NATRiUM apparatus and 11 mechanisms that affect Energy Island steam loads do 12 not directly affect the reactivity or power level of 13 the reactor, and therefore do not fall under the scope 14 of 50.54(i).
15 The topical report does not address 16 compliance with 50.54(j) though. This was 17 incorporated into the limitations and conditions that 18 will be discussed later in the presentation.
19 Unless there's questions, I'll go ahead 20 and turn it back over to Reed.
21 MEMBER HALNON: So you're talking about 22 the thermal storage system doesn't affect reactivity, 23 but it sounds like it could cause a reactor scram or 24 runback. How is that not affecting reactivity?
25 MR. SEYMOUR: The distinction made here is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
114 1 you have a category of things that directly are 2 discussed to affect reactivity, and you have a 3 category of things that the operation of which may 4 affect reactivity.
5 The distinction is that one set of things 6 falls under (i) in 50.54(i) and the other falls under 7 (j). What we're saying here in the topical is that 8 there is very well a subset of things that could fall 9 under (j). We'll cover that in a limitation that we 10 put on there.
11 MEMBER HALNON: So that's all being dumped 12 into (j)?
13 MR. SEYMOUR: That's correct, yes. So 14 it'll still be necessary for TerraPower to show how 15 they're going to comply with (j) or to go through and 16 seek some type of an exemption.
17 I would mention, and I'll build upon this, 18 during the audit we did query TerraPower on how they 19 want to pursue compliance with (j). Again, this was 20 done in audit so it's not something that's necessarily 21 reflected in safety evaluation.
22 They did provide us with a copy of their 23 draft reactivity plan. At the point that we looked at 24 it, it was still in a very rudimentary state, being 25 flushed out. But that plan was intended to, I NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
115 1 believe, eventually show how they're going to comply 2 with 50.54(j) for Energy Island operations.
3 MEMBER HALNON: So you get another bite at 4 the apple to discuss how the thermal systems could 5 affect reactivity?
6 MR. SEYMOUR: That's right. Ultimately 7 the applicability is still there for 50.54(j), which 8 puts that into a regime where you either have to 9 comply or seek an exemption from it.
10 MEMBER HALNON: Okay.
11 MR. SEYMOUR: Again, there's a significant 12 difference between (i) and (j). With 50.54(i), as I 13 talked about, there's almost a straight line going 14 back to the Atomic Energy Act.
15 MEMBER HALNON: Yes. It seems like 16 there's a success route there. It's just a matter of 17 what the documentation is going to be?
18 MR. SEYMOUR: That's correct.
19 MEMBER HALNON: Okay.
20 MR. SEYMOUR: I'll turn it over to you, 21 Reed.
22 MR. ANZALONE: I think that's one of the 23 themes of what we're talking about here. There's a 24 success path. We're kind of outlining what that 25 success path looks like, but that path has to be NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
116 1 walked.
2 Now I'm going to talk a little bit about 3 the limitations and conditions, which kind of provide 4 the contours of that path. The first limitation is 5 about key aspects of the NATRiUM design.
6 That states that applicants referencing 7 the topical would need to use a plant design that's 8 substantially similar to what was discussed in the 9 topical and that deviations that could affect the 10 safety evaluation conclusions need to be justified 11 when the topical report is referenced.
12 I think in general in the topical report 13 process, this is one of these things that's kind of 14 assumed would happen that you need to justify the 15 applicability of the topical report to your plant when 16 you reference it. But we wanted to put this in as 17 limitations to underscore the importance of those 18 design features that enable the independence of the 19 Nuclear Island and Energy Island.
20 While those regulatory evaluations that we 21 talked about were really relatively high level, we did 22 make our determinations in the context of the NATRiUM 23 design and its capabilities. Part of the reason we're 24 doing this too and putting it specifically as a 25 limitation in the condition is that there is interest NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
117 1 in applying similar approaches to decouple the Nuclear 2 Island and Energy Island that's been expressed to us 3 by other industry organizations.
4 So we wanted to kind of outline, here are 5 the things that you need to happen in the design to 6 make something like this possible.
7 Next slide.
8 So limitation condition 2 talks about the 9 safety classification process. This is sort of a 10 similar theme to the first one. They use NEI 18-04 in 11 the topical report to do the safety classification.
12 We relied on that to make our 13 determinations, but also the design process is 14 iterative. NEI 18-04 identifies that it would be 15 intended to be applied iteratively as the design 16 matures. Eric mentioned this in their presentation.
17 They've done these analyses. They are 18 doing these analyses. They're going to continue to do 19 these analyses and reconfirm as the design matures 20 that the Energy Island SSCs continue to be non-safety 21 related with no special treatment for the conclusions 22 in our safety evaluation to remain applicable.
23 So limitation 3, this is the one talking 24 about the difference in the definition between 50.2 25 and NEI 18-04 for safety-related. And I think I NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
118 1 already covered that one. I'll move on.
2 Limitation 4, there are other definitions 3 in the regulations of construction. Part 51, which is 4 the environmental regulations, also has a definition 5 of construction that's similar or possibly identical 6 to Part 50. I'm in safety licensing, not 7 environmental, so I'm not actually that familiar with 8 the environmental regulations.
9 We just wanted to make it clear that the 10 evaluation applies to the Part 50 definition of 11 construction that TerraPower evaluated. It doesn't 12 apply to any other places that construction might be 13 defined.
14 Five, and I already talked about this. We 15 haven't reviewed EOPs for NATRiUM and TerraPower 16 didn't discuss them in sufficient detail to ensure 17 they don't rely on Energy Island SSCs.
18 Six and 7, similar to 5. We're going to 19 need more information on the physical and 20 cybersecurity programs to ensure that the Energy 21 Island doesn't include SSCs that fall under the scope 22 of those programs. We think the design supports it, 23 but we didn't have enough to be able to say 24 definitively.
25 Now Jesse is going to talk about 8 and 9.
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119 1 MR. SEYMOUR: Thanks, Reed.
2 As mentioned earlier, the topical report 3 does not address the requirements of 50.54(j).
4 Therefore, we did not provide any safety evaluation of 5 the implications of NATRiUM's design as it relates to 6 that specific regulation.
7 Again, 50.54(j) deals with apparatus and 8 mechanisms, the operation of which may affect 9 reactivity. It does not require a licensed operator 10 to do those things, but a licensed operator at the 11 controls has to provide knowledge and consent.
12 Thus, any NATRiUM facility licensee or 13 applicant for an operating license or combined license 14 that references this topical report, in the absence of 15 receiving an exemption, must ensure that manipulation 16 of any Energy Island apparatus or mechanism which may 17 affect the reactivity or power level of the reactor is 18 only permitted with the knowledge and consent of a 19 licensed operator or senior operator.
20 Beyond that, 55.31(a)(5) requires that 21 reactivity manipulations for operative licensed 22 applicant experience requirements must involve 23 operating the controls which, as discussed earlier, 24 are associated with direct reactivity or power 25 changes.
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120 1 Therefore, any apparatus or mechanism 2 determined to not be a control must logically also be 3 excluded from being acceptable for applicant 4 experience credit under 55.31(a)(5). Again, this was 5 important to point out because historically we've 6 accepted those loading changes as a reactivity 7 manipulation for that type of credit.
8 So consistent with that, applicants for 9 operator or senior operator licenses at a NATRiUM 10 facility where the facility licensee references its 11 topical will not be able to rely upon manipulation of 12 apparatus and mechanisms that affect Energy Island 13 steam loads, including the turbine generator, for the 14 purposes of satisfying those operator license 15 experience requirements.
16 I'm going to turn it back over to Reed 17 again.
18 MR. ANZALONE: I'll just talk about this 19 last limitation, which is pretty simple. The topical 20 report discussed the basis for the proposed 21 exemptions. We reviewed it for information, but we're 22 not taking a perspective on the exemptions that we 23 haven't received yet in the safety evaluation.
24 MR. BLEY: Excuse me. This is Dennis 25 Bley. Could you back up one slide and go over that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
121 1 last point you made? It kind of slipped past me. I 2 didn't fully understand it.
3 MR. SEYMOUR: Sure. This is Jesse. When 4 a licensed operator applicant applies for a license, 5 one of the requirements is that they have to show they 6 conducted five significant reactivity manipulations.
7 Those can either be done on an actual plant, or with 8 a few more restrictions it can be done on a simulator.
9 One of the keys is that they have to 10 utilize the controls of the facility. Historically, 11 with the existing large light-water fleet, we have 12 accepted credit for those occurring, moving the rods, 13 berating, diluting, manipulating recirculation pumps 14 on the reactor side. And then over on the secondary 15 side changing turban loading has been something that 16 we've accepted for credit before.
17 So based upon this topical report and our 18 evaluation of it, again, it creates a little bit of a 19 logical disconnect if you were going to say that the 20 turbine and its manipulation does not constitute a 21 control on the one hand, but then on the other hand 22 allow that to still be credited for those types of 23 applications.
24 Essentially, what that condition and 25 limitation is saying there is that you can't have your NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
122 1 cake and eat it too, for lack of a better way to put 2 it.
3 MR. BLEY: Okay. I think I get it now.
4 Thank you.
5 MR. SEYMOUR: If you could go to the next 6 slide, please?
7 So the high-level conclusions. The 8 topical report is acceptable for referencing future 9 licensing submittals subject to our limitations and 10 conditions, which we think delineate that path where 11 it would be acceptable. The plant design and Energy 12 Island's safety classification, they are integral part 13 of our evaluation.
14 With that, I will open it up to any 15 questions.
16 MEMBER HALNON: On the cybersecurity side 17 when we drew the bright line back in 2010-ish time 18 frame for operating plants, are you going to carry 19 that same scope, I guess, for lack of better terms, 20 for the NRC to be into the construction as well?
21 I assume that when Vogel was constructed, 22 the NRC looked at the compliance with the New York 23 side as well, like they do in the operating plants.
24 Is that going to carry forward in these advanced 25 reactors as well?
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123 1 MR. SEYMOUR: I'm not a cybersecurity 2 expert so I can only comment so much, but that is 3 basically my understanding of where things are. We've 4 talked with the cybersecurity people about this.
5 MEMBER HALNON: Okay. So obviously, 6 there's no major change in how we're going to be 7 looking at it in the future then?
8 MR. SEYMOUR: Not to my understanding, but 9 I could be proven wrong.
10 MEMBER HALNON: Okay.
11 MR. MARCH-LEUBA: My concern with the 12 cyber is this starts defining political components.
13 Nothing in the NEI is a political component.
14 Therefore, a cybersecurity plan is not required.
15 MEMBER HALNON: Well, by the NRC's 16 standard. The NERC standard would put them into a 17 more special category.
18 MR. MARCH-LEUBA: I've always said you 19 guys have to be looked for aquariums. And the EI 20 sounds to me like an aquarium. I will tell you the 21 story after. Or just Google cybersecurity attack on 22 a casino with an aquarium.
23 MS. de MESSIERES: This is Candace de 24 Messieres of the NRC staff again. I just wanted to 25 reiterate we did explicitly put that limitation and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
124 1 condition in the topical safety evaluation just 2 because we do need more information in this area, so 3 more to come.
4 MR. SCHULTZ: Reed and Jesse, this is 5 Steve Schultz. Just to confirm in general, during the 6 presentations today from TerraPower, your review of 7 your overall evaluation, and the limitations and 8 conditions, things are aligned between you and 9 TerraPower, associated with their actions that they 10 see they need to take in regard to the exemption 11 requests?
12 MR. SEYMOUR: Yes, I would say so.
13 MR. SCHULTZ: And other follow-up actions 14 associated with the limitations and conditions?
15 MR. SEYMOUR: Yes.
16 MR. SCHULTZ: And with regard to the 17 exemptions, it doesn't seem as if they're high 18 hurdles, the Part 50 exemptions that TerraPower is 19 moving forward to obtain.
20 MR. SEYMOUR: I think I would agree with 21 that. Like I said, they laid out a lot of the basis 22 for the exemptions in the topical report, so we're 23 kind of aware of where they're going to go.
24 MR. SCHULTZ: So your limitations and 25 conditions are aligned with that as well?
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125 1 MR. SEYMOUR: Yes.
2 MR. SCHULTZ: Thank you.
3 CHAIR ROBERTS: Are there any other 4 questions from the members online?
5 MEMBER KIRCHNER: No, thank you, Tom.
6 CHAIR ROBERTS: Thanks, Walt.
7 Hearing none, I have one final question 8 for the staff. Is there anything in this topical 9 report you think was innovative or kind of ground-10 breaking or just kind of the normal process of doing 11 business with the pre-application phase?
12 MR. SEYMOUR: I would say the whole 13 concept is kind of innovative and ground-breaking, but 14 I think that's mostly just because nobody has really 15 had a technology that seemed to us to be capable of 16 doing this previously.
17 I think for a lot of the reasons that 18 Jesse and I have laid out, it's not something that you 19 could do with a large light-water reactor with the 20 current designs that are in the operating fleet. So 21 it took somebody coming up with a design that was 22 capable of doing this and then trying to put into 23 practice.
24 I think there is some ongoing things that 25 TerraPower is going to need to make sure of. I'm NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
126 1 confident that they are going to do that because this 2 is one of their key design principles, to maintain the 3 separation between the Energy Island and the Nuclear 4 Island.
5 But as they go through the process, 6 they're going to have to continue to try to reinforce 7 that separation to be able to make sure that these 8 things can actually be followed through as they're 9 described in the topical report. I'll leave it at 10 that.
11 MR. BLEY: This is Dennis. Could I ask a 12 question of TerraPower? Throughout this discussion, 13 you talked a lot about using the LMP. We've heard 14 some complaints from people about how arduous that is.
15 So I have two questions for you. One is, 16 can you describe a little bit how you found the use of 17 the LMP in your projects so far?
18 Two, do you have any comments on the 19 limitations and conditions the staff has placed in 20 their review? Were they surprises to you or are you 21 pretty comfortable with them?
22 MR. JOHNSON: This is Brian Johnson on the 23 line, Manager of Nuclear Safety Licensing leading up 24 the risk reliability efforts and a lot of the LMP 25 implementation.
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127 1 I will agree. I think the LMP is somewhat 2 arduous, but I think it's a worthwhile and good way to 3 establish a positive safety case that's thorough early 4 on.
5 I think it's also going to be something we 6 want to leverage to defend things like our safety 7 classifications so that they don't drag on, that we 8 have an agreed-upon systematic basis for making those 9 determinations, rather than ad hoc determinations 10 based on whatever negotiation we can do, whatever 11 precedent exists.
12 So that experience of developing the PRA 13 and going through the LMP, I think, has been overall 14 good and that we have gotten significant insight from 15 that process.
16 I'm not going to speak directly to the 17 limits and conditions of the topical here, but I did 18 want to say that has been our overall experience with 19 LMP. Yes, it's a lot of work, but it gives worthwhile 20 insights.
21 MR. WILSON: This is George Wilson of 22 TerraPower. We expected that we were going to get 23 limitations and conditions on the topical report for 24 where we were at.
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128 1 was open, our logic was there, and the regulatories 2 flow past so that we can continue through the process.
3 So we expected the limitations and the conditions that 4 we received.
5 MR. BLEY: Gentlemen, thanks.
6 CHAIR ROBERTS: Are there any other 7 questions for the staff or the applicant? Now is the 8 time on the agenda for comments from members of the 9 public. If anybody online would like to make a 10 comment, please go ahead and unmute yourself, state 11 your name and organization, and make your comment.
12 Hearing none -- there is a hand, okay.
13 What does the hand mean?
14 MR. LYMAN: Ed Lyman.
15 CHAIR ROBERTS: Yes, hello. Go ahead.
16 MR. LYMAN: This is Ed Lyman from the 17 Union of Concerned Scientists. I'd just like to bring 18 up one point. I've heard from a reliable source that 19 the estimated capital cost of this project has doubled 20 from original estimates.
21 I don't know if that means from the $4 22 billion that was originally stated, meaning you would 23 be up to $8 billion. Clearly, the molten salt storage 24 aspect is a substantial contributor to that capital 25 cost.
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129 1 I would anticipate there may be design 2 changes along the way to try to address the capital 3 cost increase that could impact the conclusions now 4 that we've reached here. So I'm just raising that as 5 an issue, perhaps for the committee to keep in mind, 6 but some of these redundancies may go away. Thank 7 you.
8 CHAIR ROBERTS: Thank you. Are there any 9 other members of the public that would like to make a 10 statement?
11 Hearing none and seeing no additional 12 hands raised, now is time for the Committee 13 discussion. I guess I'll start by suggesting from 14 what we heard today, I would suggest that we would not 15 need to write a letter because of various reasons.
16 One is the limitation condition number 2 17 in the topical report. Basically you can go through 18 this whole line of reasoning on the actual design as 19 it's produced.
20 There's nothing really that's being 21 committed to at this point other than acknowledging 22 that the process leads to the types of interaction 23 that you've heard today. I'd be interested from the 24 members if people see it that way or have different 25 views.
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130 1 MEMBER MARCH-LEUBA: I'm a proponent of 2 not writing those when it's not needed. Whenever 3 there is a new and novel concept in its first 4 application, I think in years later will have value.
5 The energy out from Nuclear Island is the first time 6 I've seen it implemented. I think having a position 7 for FCRS is okay.
8 MEMBER HALNON: I absolutely hate agreeing 9 with Jose, but I think that it serves a couple of 10 purposes. One is there's a couple of items that I 11 think we still need to keep our eye on.
12 That is the requirement for the operators 13 to maintain pre-existing conditions prior to a 14 transient in order for that operating envelope to say 15 within the bounds of where it needs to be so that they 16 don't have to respond to an accident condition.
17 That's more on the nuclear side than 18 Energy Island side, but I'm interested in the how tech 19 specs would roll out, procedures, EOPs, and those 20 types of things before we could say that we agree, 21 there's a clear distinction here where there's no 22 license operators on Energy Island.
23 Secondly, to Jose's point, it's a 24 progressive aspect of our committee to give a green 25 light, if that's what we're going to be, which I think NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
131 1 we should be, to a novel concept to move forward with.
2 I think we concluded, or at least I concluded in my 3 mind, that both the staff and the applicants have done 4 a good job to lay groundwork for future work that has 5 a clear success path, but there's still some hurdles 6 to get beyond.
7 Not just the exemptions, but some of the 8 other analyses that have to be done. I think there's 9 a good aspect to putting a green light on that, but 10 also the cautionary aspect of some things that still 11 need to be shaken out.
12 MEMBER REMPE: I agree with the members 13 who have spoken, except that I have more problems with 14 agreeing with Greg than Jose.
15 MEMBER PETTI: I'm just concerned with how 16 we write such a letter. It's kind of like a green 17 light but putting your foot on the break because 18 there's these issues out there that you really can't 19 evaluate until the design gets more mature.
20 So if we do it, it's going to have to be 21 really carefully worded. Is it viewed as a full green 22 light? The staff didn't give them the full green 23 light. This is kind of a blinking yellow at best.
24 We don't usually write letters like that.
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132 1 back again. It's sort of an issue of when is the 2 optimal time.
3 MEMBER REMPE: There are some things that 4 we will be evaluating as we go forward. It's not 5 really cautions. It's just, hey, there's some 6 outstanding.
7 I'm sorry I interrupted you, Vesna. Go 8 ahead.
9 MEMBER DIMITRIJEVIC: That's okay because 10 that's the limits of my ability to participate in this 11 discussion. This is just conceptual, the approach.
12 So I don't really think that there is a 13 reason for us to write the letter before the design is 14 complete. They're still going to talk with us about 15 human factors that we don't completely understand yet 16 until the PRA is completed.
17 So basically, what they have been saying 18 is technically that Energy Island can be separated 19 from Nuclear Island. And therefore, the components 20 there would not require the same certification, but 21 this is just concept until these other things are 22 complete.
23 MEMBER BROWN: This is Charlie. Are you 24 finished, Vesna?
25 MEMBER DIMITRIJEVIC: Yes.
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133 1 MEMBER BROWN: I guess I would agree with 2 Tom and Vesna. They've just laid out a concept for 3 how we would like to go. They've given us the plant 4 concept for how to get separation, but there's a whole 5 pile of additional items that need to be evaluated 6 relative to exemptions and the limitations and 7 conditions, which we don't have any closure on at all.
8 I would prefer to have some more detail of 9 how they're actually going to finish rowing the boat 10 through these rapids before we write a letter on it 11 because right now, all we can say is maybe. So I 12 would vote for no letter at this particular time.
13 That would be my position.
14 MEMBER BALLINGER: This is Ron Ballinger.
15 From the standpoint of the technical side, I agree 16 with Tom. We don't need a letter. But what we're 17 talking about here is something which has a much 18 larger implication going forward.
19 What we're talking about here is basically 20 spending reserve for these plants. In the future, 21 it's like putting a battery on the grid in effect, and 22 not having the transmission lines from a freaking --
23 excuse my French -- from a wind turbine somewhere.
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134 1 which we may want to at least point out. I don't know 2 whether we want to do that in a letter or not, but 3 this concept has larger implications, although people 4 say it's existed for a long time. What's the 5 difference between that and pump storage, I guess.
6 MEMBER HALNON: If you go just a little 7 bit further, Ron, it may not be an Energy Island. It 8 may be a chemical plant. You don't want to put 9 nuclear licensed operators at a chemical plant because 10 they could indirectly affect reactivity by changing 11 their chemical processing. So it's got further 12 implications even broader than that.
13 It's also -- correct me if I'm wrong --
14 this is the first licensing action that TerraPower has 15 asked for. Is that correct?
16 PARTICIPANT: This is the first time.
17 MEMBER HALNON: To show progress in the 18 advanced reactor world, I think it's important that we 19 show the committee is engaged and going forward. Yes, 20 we don't give a complete green light, I agree, to the 21 separation of Energy Island from Nuclear Island.
22 I think it's even beyond conceptually when 23 we see a clear path. There's regulatory hurdles to 24 get over, but they're regulatory hurdles, not 25 necessarily physical. There might be one or two NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
135 1 physical ones that we pointed out. I think it's 2 important for us to endorse a potential path forward 3 for not just energy islands but chemical process 4 plants, hydrogen plants.
5 MEMBER BALLINGER: In theory, they could 6 shut that down from the salt loop to the Nuclear 7 Island, and just run the turbine and generate power 8 until they ran out of heat.
9 MEMBER HALNON: Yes, until the tank is 10 empty.
11 MEMBER REMPE: Okay. The letter would not 12 occur until October Full Committee week if it were to 13 occur. So I would recommend that you take a vote 14 through the subcommittee and then during P&P September 15 Full Committee, it will become an official committee 16 decision on this.
17 So why don't you give a recommendation to 18 go forward or not to go forward from the subcommittee.
19 And then you'll have to present it at full committee 20 in September.
21 If it does not go forward, you need to 22 have a paragraph that could go into them needing 23 summary notes. I don't think there's more than a 24 subcommittee could do right now. You might want to 25 take a vote and decide what the consensus or the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
136 1 majority is.
2 MEMBER MARCH-LEUBA: The subcommittee does 3 both, right?
4 MEMBER REMPE: You can have a soft P&P and 5 have a recommendation for the subcommittee. That's 6 what I'm trying to say. I hear both sides of the 7 aisle and I'm kind of stepping in to help you out 8 here.
9 CHAIR ROBERTS: Okay. So our subcommittee 10 vote would be to enter P&P with a recommendation to 11 either write a letter or not write a letter for 12 presentation at the October meeting?
13 MEMBER REMPE: If there is going to be a 14 letter, then there would be a presentation in October.
15 The one question I didn't hear asked is did the staff 16 or the applicant request a letter from ACRS?
17 It does cost the applicant to take time to 18 do a presentation. You can do it remotely. You don't 19 have to fly in or anything.
20 MS. SUTTON: Neither the staff nor the 21 applicant requested a letter. I know we do have a 22 proposed date for October 4th if it was needed. So I 23 guess we will know in September if we will support a 24 full committee.
25 MEMBER REMPE: And there's nothing that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com
137 1 having to wait until that October -- are there 2 decisions being made by the applicant or the staff 3 other than you can't issue your SC without our letter 4 if we're going to have a presentation? But there's 5 nothing like a real operating plant. Sometimes we're 6 delaying something but we're not really.
7 MS. SUTTON: There's no ground-breaking.
8 There's no construction being done, no construction 9 activities. So at this time we just have several 10 topical reports. We have six in house that we're 11 reviewing that will potentially come to the 12 subcommittee.
13 MEMBER HALNON: Is it required that we 14 have a full committee presentation? Since the 15 subcommittee is the full committee, why can't we just 16 say let's have a one-hour deliberation and then go 17 into letter writing?
18 MEMBER REMPE: Are there any members not 19 present today?
20 MEMBER HALNON: That is an option.
21 MEMBER MARCH-LEUBA: What we do in this 22 case is we ask the staff to make a summary 23 presentation of ten to 15 minutes, and have the 24 applicant on the phone in case there's a question.
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138 1 lingering questions.
2 MEMBER MARCH-LEUBA: They don't have to 3 travel.
4 MEMBER REMPE: Absolutely, yes. They 5 don't have to. Anyway, I'd take some sort of vote on 6 the recommendation.
7 CHAIR ROBERTS: Let's go ahead and take a 8 vote. The vote would be on whether a P&P coming up in 9 two weeks, whether it's the recommendation of the 10 subcommittee that the full committee meet to 11 deliberate a letter.
12 Does that make sense? A yes vote would be 13 to proceed with a letter and a no vote would be to not 14 proceed with a letter. How would you vote?
15 MEMBER KIRCHNER: I personally would make 16 a summary and not do a letter. My reasons would be 17 that I think we would find ourselves repeating all the 18 limitations and conditions that the staff has 19 discussed as parent of their deliberations in FC.
20 I'm not sure that this would really --
21 again, we're at a conceptual phase. There are lots of 22 questions yet that will depend on the details that 23 will be forthcoming for the applicant. So I guess at 24 this point, I would not write a letter, just put a 25 summary entry into our record.
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139 1 CHAIR ROBERTS: Thanks, Walt.
2 Vesna?
3 MEMBER DIMITRIJEVIC: Same here. I 4 already said that, a summary note.
5 CHAIR ROBERTS: Let's get a show of hands 6 in the room of who would write a letter? And who 7 would proceed with writing a summary and the P&P but 8 not form a letter?
9 The vote is five plus two, so seven to 10 four to proceed on the basis of not writing a letter.
11 I'll draft a paragraph for the P&P coming up in two 12 weeks, and then we'll have another discussion and 13 another vote at that point.
14 MEMBER MARCH-LEUBA: Procedurally, you 15 would present a recommendation of the subcommittee to 16 the full committee. Hopefully, nobody will change 17 their mind. The decision would be on the full 18 committee.
19 CHAIR ROBERTS: Okay. Thanks, Jose.
20 MEMBER MARCH-LEUBA: The staff and 21 applicant can probably assume that you won't write the 22 letter, but you won't know until September.
23 MS. SUTTON: This is Mallecia. I just want 24 to clarify. Is the vote to actually write a summary?
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140 1 meeting? No letter but the summary of the meeting?
2 MEMBER REMPE: Just to clarify, this 3 summary is just, hey, the subcommittee met. We 4 discussed this. The general people were favorable.
5 We supported the LNCs, the limitations and conditions, 6 whatever comments. You're done.
7 CHAIR ROBERTS: This is our record that we 8 made a decision not to do a letter.
9 MS. SUTTON: I just wanted to make sure we 10 are on the same page. Thank you.
11 MEMBER BROWN: You're clean.
12 MR. MOORE: This is Scott Moore, the 13 Executive Director. We prepare a summary for each full 14 committee meeting. It would go into that. The summary 15 is publicly available in ADAMS. It would describe 16 whatever the full committee decides to do on this.
17 The full committee could still decide to 18 write a letter, as Jose has pointed out, but it's 19 unlikely given that you've got, I think, everybody 20 here. You can see it in the summary and so can the 21 public.
22 MEMBER REMPE: Sometimes an applicant or 23 licensee likes that summary saying that even though 24 they didn't write a letter, they supported it.
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141 1 caveat that we reviewed all the stuff and it's not 2 unreasonable, but no closure on things, however Tom 3 can phrase it in a happy manner.
4 MR. KELLENBERGER: So we would know in 5 September whether we need to come back for the full 6 committee in October?
7 CHAIR ROBERTS: No surprises.
8 MEMBER REMPE: We'll make sure to let you 9 know.
10 CHAIR ROBERTS: Are there any other 11 comments that the members or consultants would like to 12 make?
13 MEMBER HALNON: Just thank you to 14 TerraPower for coming in. We greatly appreciate face-15 to-face communications when we can get it, so we 16 appreciate it very much that you were here.
17 CHAIR ROBERTS: I'd like to reiterate what 18 Greg said. I appreciate the presentations from both 19 TerraPower and NRC staff. They were excellent. I 20 think our questions got answered to the extent that it 21 could be answered given the preliminary nature of the 22 concept design.
23 With that, this meeting is adjourned.
24 (Whereupon, the above-entitled matter went 25 off the record at 11:29 a.m.)
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Staff Review of NATD-LIC-RPRT-0001, Regulatory Management of Natrium Nuclear Island and Energy Island Design Interfaces Mallecia Sutton, Senior Project Manager, NRR/DANU Reed Anzalone, Senior Nuclear Engineer, NRR/DANU Jesse Seymour, Senior Reactor Engineer (Examiner), NRR/DRO
Agenda
- Review Chronology
- TR Overview and Review Strategy
- Safety Evaluation Overview
- Plant design and transients
- Safety classification using NEI 18-04
- Regulatory evaluations
- Limitations and conditions
- Conclusions 2
Review Chronology
- Pre-Application Public Meeting
- November 17, 2021
- Submittals on Decoupling Strategy
- White Paper: Energy Island Decoupling Strategy February 4, 2022 (voluntarily withdrawn)
- Topical Report: Regulatory Management of Natrium Nuclear Island and Energy Island Design Interfaces October 4, 2022
- TR Accepted
- November 16, 2022
- Audit Conducted
- January 23, 2023 - March 10, 2023
- Final Draft Safety Evaluation Issued
- August 10, 2023 3
TR Overview and Review Strategy
- Purpose of TR:
- The independence of operation between the systems contained within the NI and the plant systems composing the EI is a key aspect of the Natrium design philosophy.
The NI boundary conditions have been intentionally designed so the interrelationship with the EI does not impact the NI safety case.
- [E]valuate regulatory impacts of the Natrium design interfaces with respect to the interaction of NI and EI systems
- Review Strategy
- Examine key aspects of Natrium design and analysis presented in the TR
- Assess regulatory evaluations in the context of these key aspects
- Propose appropriate limitations and conditions necessary for evaluations to be acceptable 4
Safety Evaluation Overview
- Sections 1 Introduction and Background
- Section 5 - Staff Evaluation
- Section 5.1 - Natrium Plant Design and Transients
- Section 5.2 - Natrium Safety Classification of SSCs
- Section 5.3 - Regulatory Analyses
- Section 6 - Limitations and Conditions
- Section 7 - Conclusions 5
6 Plant Design and Response to Transients SHX TSS IAC SGS RAC NI EI IHT PHT Images sourced from NATD-LIC-RPRT-0001, Regulatory Management of 6
Natrium Nuclear Island and Energy Island Design Interfaces (ML22277A824)
Safety Classification Using NEI 18-04*
- NEI 18-04 endorsed in RG 1.233, Guidance for a Technology-Inclusive, Risk-Informed, and Performance-Based Methodology to Inform the Licensing Basis and Content of Applications for Licenses, Certifications, and Approvals for Non-Light-Water Reactors
- Risk-informed, performance-based safety classification is integrated with other aspects of NEI 18-04 process, including selection and analysis of licensing basis events and evaluation of defense-in-depth adequacy
- Different definition for safety-related SSCs than 10 CFR 50.2
- NEI 18-04, Risk-Informed Performance-Based Technology Inclusive Guidance for Non-Light Water Reactor Licensing Basis Development, Revision 1 (ML19241A472) 7
Safety Classification Using NEI 18-04 8
From NEI 18-04, Rev. 1 (ML19241A472)
9 Role of F-C target in Safety Classification DBEs Only SR SSCs available to keep DBAs below 10 CFR 50.34 dose limit High Consequence BDBEs 9
From NEI 18-04, Rev. 1 (ML19241A472)
Overview of Regulations Covered in TR
- 10 CFR 50.10, License required; limited work authorization
- 10 CFR 50.65, Requirements for monitoring the effectiveness of maintenance at nuclear power plants
- 10 CFR 50 Appendix B, Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants
- 10 CFR 55, Operators Licenses 10
10 CFR 50.10 (LWA rule) Overview
- 10 CFR 50.10(c): [n]o person may begin the construction of a production or utilization facility on a site on which the facility is to be operated until that person has been issued either a [construction permit] or a limited work authorization [LWA] .
- 10 CFR 50.10(a)(1) provides scoping criteria defining construction.
- Rule issuance FRN (72 FR 57415) notes that scoping criteria were chosen to encompass those SSCs that have a reasonable nexus to radiological health and safety or common defense and security.
11
Activities constituting construction are the driving of piles, subsurface preparation, placement of backfill, concrete, or permanent retaining walls within an excavation, installation of foundations, or in-place assembly, erection, fabrication, or testing, which are for:
(i) Safety-related structures, systems, or components (SSCs) of a facility, as defined in 10 CFR 50.2; (ii) SSCs relied upon to mitigate accidents or transients or used in plant emergency operating procedures; (iii) SSCs whose failure could prevent safety-related SSCs from fulfilling their safety-related function; (iv) SSCs whose failure could cause a reactor scram or actuation of a safety-related system; (v) SSCs necessary to comply with 10 CFR part 73; (vi) SSCs necessary to comply with 10 CFR 50.48 and criterion 3 of 10 CFR part 50, appendix A; and (vii) Onsite emergency facilities, that is, technical support and operations support centers, necessary to comply with 10 CFR 50.47 and 10 CFR part 50, appendix E.
12
13 10 CFR 50.10(a)(1) Evaluation Criterion TerraPower Staff (i) Not applicable because EI SSCs are Reasonable, consistent with NEI 18-04 safety NST. classification definition. See L&C 3 regarding definition of safety-related.
(ii) Not applicable because EI SSCs are not Consistent with plant design. Would not expect NST used to mitigate accidents or SSCs to participate in mitigation or prevention.
transients or used in EOPs. Not enough information on EOPs. See L&C 5.
(iii) Not applicable because NST SSCs Consistent with NEI 18-04 safety classification would not be capable of preventing SR definition.
SSCs from fulfilling safety functions.
(iv) Applicable because failure of EI SSCs Agree with determination that criterion is applicable.
could eventually cause a reactor trip. Reasonable to use same exemption basis for 10 CFR Plan to seek exemption. Exemption 50.10(a)(1)(iv) and 10 CFR 50.65(b)(2)(iii). Not taking a basis would be the same for 10 CFR position on prospective exemptions. See L&C 10.
50.10(a)(1)(iv) and 10 CFR 50.65(b)(2)(iii). 13
14 10 CFR 50.10(a)(1) Evaluation Criterion TerraPower Staff (v) Not applicable because no physical Appears consistent with design, but not enough security program SSCs are on EI; CDAs information to support. See L&C 6.
will not be installed on EI prior to CP.
(vi) Not applicable because fires on EI will Adequate because EI SSCs are NST and safe shutdown not prevent ability to maintain and can be achieved and maintained solely with NI achieve safe shutdown. systems.
(vii) Not applicable because onsite Consistent with plant design, but not enough emergency facilities will not be located information to support. See L&C 7.
on EI.
14
10 CFR 50.65 (Maintenance Rule)
- Requires licensees to have a program that monitors the performance or condition of certain SSCs or demonstrates the performance or condition of these SSCs through appropriate preventative maintenance, to provide reasonable assurance that they are capable of fulfilling their intended functions.
- Scope of SSCs considered under the Maintenance Rule are in 10 CFR 50.65(b)
- 10 CFR 50.65(b)(1) is similar to 10 CFR 50.10(a)(1)(i)
- 10 CFR 50.65(b)(2)(i) through (iii) are identical to 10 CFR 50.10(a)(1)(ii) through (iv) 15
10 CFR 50.65 Evaluation
- TerraPower did not evaluate 10 CFR 50.65(b)(1).
- TerraPower determined criteria (i) and (ii) are not applicable. Staff discussions and conclusions are the same as for 10 CFR 50.10(a)(1)(ii) and (iii).
- TerraPower determined criterion (iii) is applicable and plans to seek an exemption. Staff discussion and conclusions are the same as for 10 CFR 50.10(a)(1)(iv).
16
- Appendix B applies to all activities affecting the safety related functions of SSCs that prevent or mitigate the consequences of postulated accidents that could cause undue risk to the health and safety of the public.
17
10 CFR 50, Appendix B Evaluation
- TerraPower asserted that all EI SSCs will be NST, and SSCs classified as NST under the NEI 18-04 process are not capable of affecting the SR functions of SSCs used for prevention or mitigation.
- Staff considered the role of NST SSCs and determined TerraPowers evaluation was acceptable
- RG 1.233 Staff Position C.2 states, in part: The staff expects that SSCs that provide essential support (including required human actions) for SR or NSRST SSCs will be classified in a manner consistent with the higher-level function, even if the supporting SSC is not explicitly modeled in the PRA.
18
- TerraPower states that the Natrium design removes direct interaction between the reactor and the turbine generator
- Turbine operations would not be an apparatus or mechanism whose manipulation directly affects the reactivity or power level of the reactor
- Natrium design should allow for a non-licensed individual to fully operate the turbine generator
- Staff evaluated that the nature of the TSS is consistent with Natrium not treating turbine generator operations as a control as defined under 10 CFR 50.2 and 10 CFR 55.4
- A key consideration is the term direct and its specific meaning within the definition of controls 19
- The AEA Section 11 defines operators as individuals who manipulate the controls of utilization facilities; definition of controls is left to the NRC
- Section 107 further mandates that individuals who operate utilization facility controls must be licensed by the NRC.
- Manipulation of the controls is restricted to licensed operators under 10 CFR 50.54(i)
- Definition of controls in Parts 50 & 55 dates back to 1963 (28 FR 3197)
- Narrowed from an earlier, broader definition; FRN notes that this [current] narrower interpretation is in accord with the original Commission intent.
- The direct aspect of a control means they cause reactor power level or reactivity changes without needing something intermediate to make that happen
- Natrium TSS is a significant intermediary from a reactivity standpoint 20
L&C 1 - Key Aspects of Natrium Design
- Applicants referencing TR must use a plant design that is substantially similar to what was discussed in TR. Any deviations from plant design discussed in TR that could affect SE conclusions must be justified when the TR is referenced.
- Staff underscores the importance of the design features that enable the independence of the NI and EI. While the regulatory evaluations may be relatively high-level, the staffs determinations were made in the context of the Natrium design and its capabilities.
21
L&Cs 2&3 - Safety Classification; Definition of Safety-Related
- L&C 2
- Staffs conclusions rely on the use of the NEI 18-04 process for safety classification and a determination that all EI SSCs are classified as NST.
- Design process is iterative; so is NEI 18-04. As design matures, TerraPower will need to ensure EI SSCs continue to be NST for conclusions to be applicable.
- L&C 3
- Definition of SR in NEI 18-04 is different from that in 10 CFR 50.2.
- Some regulations explicitly reference 10 CFR 50.2 definition rather than simply saying safety-related.
- Use of NEI 18-04 may require exemptions from 10 CFR 50.2 and regulations that refer to it.
22
L&Cs 4 Evaluation of 10 CFR 50.10 and 10 CFR 50.65
- L&C 4 - TerraPower did not address definitions of construction outside of 10 CFR 50.10; this limitation makes the scope of the TR clear.
- L&C 5 - Staff has not reviewed EOPs for Natrium and TerraPower did not discuss in sufficient detail to ensure they do not rely on EI SSCs.
- L&Cs 6&7 - TerraPower did not discuss physical and cyber security programs or onsite emergency facilities in sufficient detail for staff to ensure the EI does not include SSCs that fall under the scope of 10 CFR 50.10(a)(1)(v) and (a)(1)(vii).
23
L&Cs 8 Evaluation of 10 CFR 55
- L&C 8 - 10 CFR 50.54(j) not addressed in TR.
- L&C 9 - Since manipulating the EI does not directly change reactivity or power, operator licensing experience requirements under 10 CFR 55.31(a)(5) are not satisfied by operating the EI.
24
L&C 10 - Prospective Exemption Requests
- TR discussed basis for proposed exemptions.
- Staff reviewed for information but did not take a position on prospective exemptions in the SE.
25
Conclusions TR is acceptable for referencing in future licensing submittals, subject to limitations and conditions.
Plant design and EI SSC safety classification [assumptions] are integral parts of staffs evaluation.
26
Abbreviations BDBE - Beyond design basis event L&C - Limitation and/or condition SSC - Structure, system, or component CFR - Code of Federal Regulations LWA - Limited work authorization SE - Safety evaluation CP - Construction permit NEI - Nuclear Energy Institute SR - Safety related CDA - Critical digital assets NI - Nuclear island TR - Topical report DBA - Design basis accident NSRST - Non-safety related with special TSS - Thermal salt storage system treatment DBE - Design basis event NST - Non-safety related with no special EI - Energy Island treatment EOP - Emergency operating procedure PHT - Primary heat transport system F-C - Frequency-consequence QA - Quality assurance FR - Federal Register RAC - Reactor air cooling system FRN - Federal Register notice RG - Regulatory guide IAC - Intermediate air cooling system SGS - Steam generation system IHT - Intermediate heat transport system SHX - Sodium/salt heat exchanger 27
28 From NEI 18-04, Rev. 1 (ML19241A472)
August 17, 2023 TP-LIC-LET-0094 Project Number 99902100 U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 ATTN: Document Control Desk
Subject:
Submittal of Presentation Material for Advisory Committee on Reactor Safeguards Subcommittee Meeting This letter provides the TerraPower, LLC presentation material for the August 23, 2023 Advisory Committee on Reactor Safeguards Subcommittee meeting (Enclosure 1).
This letter and enclosures make no new or revised regulatory commitments.
If you have any questions regarding this submittal, please contact Ryan Sprengel at rsprengel@terrapower.com or (425) 324-2888.
Sincerely, Ryan Sprengel Director of Licensing, Natrium TerraPower, LLC Enclosure 1: TP-LIC-PRSNT-0014, Regulatory Management of Natrium Nuclear Island and Energy Island Design Interfaces cc: Mallecia Sutton, NRC William Jessup, NRC Nathan Howard, DOE Jeff Ciocco, DOE 15800 Northup Way, Bellevue, WA 98008 www.TerraPower.com P. +1 (425) 324-2888 F. +1 (425) 324-2889
ENCLOSURE 1 TP-LIC-PRSNT-0014, Regulatory Management of Natrium Nuclear Island and Energy Island Design Interfaces
Regulatory Management of Natrium Nuclear Island and Energy Island Design Interfaces a TerraPower & GE-Hitachi technology TP-LIC-PRSNT-0014 SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved.
Table of Contents
- Natrium' Reactor Overview
- Operational Flexibility
- Transient Separation
- Regulatory Impacts SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 2
Natrium Safety Features
- Pool-type Metal Fuel SFR with Molten Salt Control Energy Island - Motor-driven control rod runback and
- Metallic fuel and sodium have high compatibility scram follow
- No sodium-water reaction in steam generator
- Gravity-driven control rod scram
- Large thermal inertia enables simplified response to abnormal events - Inherently stable with increased power or temperature
- Simplified Response to Abnormal Events
- Reliable reactor shutdown Cool
- Transition to coolant natural circulation - In-vessel primary sodium heat transport
- Indefinite passive emergency decay heat removal (limited penetrations)
- Low pressure functional containment - Intermediate air cooling natural draft flow
- No reliance on Energy Island for safety functions - Reactor air cooling natural draft flow -
always on
- No Safety-Related Operator Actions or AC power Contain
- Technology Based on U.S. SFR Experience - Low primary and secondary pressure
- EBR-I, EBR-II, FFTF, TREAT - Sodium affinity for radionuclides
- SFR inherent safety characteristics demonstrated - Multiple radionuclides retention boundaries through testing in EBR-II and FFTF SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 3
6 7 1.1 Control Building 2
2.2 Fuel Handling Building 3 1 5 4
3.3 Reactor Building 4.4 Reactor Auxiliary Building 5.5 Salt Piping 6.6 Steam Generation 7.7 Turbine Building SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 SUBJECT TOCopyright© 2023 TerraPower, DOE COOPERATIVE AGREEMENT LLC.
NO.All Rights Reserved.
DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved.
Reactor Building Reactor Aux. Building Fuel Handling Building Reactor Air Cooling Ducts Refueling Access Area Intermediate Salt Piping to/from Air Cooling Thermal Storage System Sodium Int. loop Ground Level Sodium/Salt HXs Spent Fuel Pool (water)
Intermediate Sodium Hot Leg Head Access Area Intermediate Sodium Cold Leg Reactor and Core Reactor Air Cooling / Reactor Cavity SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 5
Energy Island Live steam Steam drum Hot salt Cold from salt to reactor reactor Superheater Cold salt Hot salt pump Preheater pump Evaporator Attemperation Feedwater pump Reheater Cold reheat Hot Tank Cold Tank Hot reheat SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 6
Operational Flexibility
.SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 7
Operational Flexibility
- Scope of NI command and control
- Licensed Reactor Operator controls reactor power
- Allows NI operators to focus on safely operating the nuclear heat source
- Reactor power independent of turbine output
- Grid Operator controls turbine output based upon grid demand
- Reactor remains at full power while turbine output variations are accommodated via salt tank inventory management
- Requirements related to salt tank levels, controlled bands, alert levels, and response times will be verified by initial modeling and reflected throughout design process
- Immediate reactor plant response to changes in EI heat rejection systems are not necessary SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 8
Operational Flexibility
- Molten salt storage tanks change the direct correlation between reactor power and steam demand SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 9
Transient Separation
.SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 10
EI Initiated Transients
- All failures associated with the EI are grouped into:
- Loss of or reduced heat removal of IHT system via NSS:
- Loss of salt flow
- High salt temperature
- Low salt pressure
- Increased heat removal of IHT system via NSS:
- Increased salt flow
- Low salt temperature SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 11
Event Type Line Diagram by Frequency Decreasing Frequency All Events Quantified Events (Assigned a Consequence)
PRA Modeled Events (QHOs Calculated here)
Normal Ops Screening Initiating Event Screening Residual Region Licensing Basis Events Other Quantified Events AOO DBE BDBE EPZ/Cliff Edge DID Only Demonstrates Meets F-C Target Evaluates potential for cliff edge and DID adequacy or DBA events contributing other important to EPZ evaluation safety feature Meets 10 CFR 50.34 dose limits Derived from DBE, no frequency assigned SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 12
Transient Separation Defense-in-Depth
- Plant safety analyses only model PIEs that directly impact the NI
- All DL3 and DL4 functions are performed by NI systems SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 13
Transient Separation
- With operational flexibility, most events on the EI that would affect the NI in a typical nuclear power plant have no immediate impact
- EI events can lead to PIEs if resulting change to an interface parameter occurs
- Plant design ensures that EI SSCs are not required to perform any DL functions other than very few selected DL2 functions on the EI
- Enables no safety-related DL3 SSCs on the EI SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 14
Plant Response to EI Transients
- Decrease or increase in heat removal from NSS leads to increased sodium temperature or decreased sodium temperature in IHT respectively
- Thermal inertia in IHT and PHT provides adequate time to respond to the event via signals monitored within NI
- Power runback:
- Reactor power decreased by insertion of control rods at predetermined rate
- IAC and RAC provide system heat removal
- PSP/ISP flow decreased to target flow settings
- NSS isolation
- Reactor SCRAM:
- Reactor power decreased by control rod drop via gravity
- IAC and RAC provide system heat removal
- PSP/ISP ramp down
- NSS isolation SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 15
Regulatory Impacts
.SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 16
Regulatory Impacts
- Future Exemption Requests
- 10 CFR 50.2, Definitions
- 10 CFR 50.10, License required; limited work authorization
- 10 CFR 50.65, Requirements for monitoring the effectiveness of maintenance at nuclear power plants
- Requirements not applicable to NST SSCs on the EI
- 10 CFR 50 Appendix B, Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants
- Turbine operation by a Licensed Operator is not required
- 10 CFR 55, Operators Licenses SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 17
Questions?
.SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 18
Acronym List AOO - Anticipated Operational Occurrence IHT - Intermediate Heat Transport System BDBE - Beyond Design Basis Event ISP - Intermediate Sodium Pump CCF - Common Cause Failure NI - Nuclear Island CFR - Code of Federal Regulations NSS - Nuclear Island Salt System DBA - Design Basis Accident NST - Non-Safety-Related with No Special Treatment DBE - Design Basis Event PHT - Primary Heat Transport System DID - Defense-in-Depth PIE - Postulated Initiating Event DL - Defense Line PRA - Probabilistic Risk Assessment EBR - Experimental Breeder Reactor PSP - Primary Sodium Pump EI - Energy Island QHO - Quantitative Health Objectives EPZ - Emergency Planning Zone RAC - Reactor Air Cooling System F-C - Frequency-Consequence SFR - Sodium Fast Reactor FFTF - Fast Flux Test Facility SHX - Sodium-Salt Heat Exchanger HXs - Heat Exchangers SSC - Structure, System, and Component IAC - Intermediate Air Cooling System TREAT - Transient Reactor Test SUBJECT TO DOE COOPERATIVE AGREEMENT NO. DE-NE0009054 Copyright© 2023 TerraPower, LLC. All Rights Reserved. 19