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Transcript for the Advisory Committee on Reactor Safeguards Accident Analysis & Thermal-Hydraulic Subcommittee Meeting - November 2, 2020, Pages 1-104 (Open)
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Issue date:	11/02/2020
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	Abdullahi, Z, ACRS
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Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION

Title:

Advisory Committee on Reactor Safeguards Accident Analysis and Thermal-Hydraulic Subcommittee: Open Session Docket Number:

(n/a)

Location:

teleconference Date:

Monday, November 2, 2020 Work Order No.:

NRC-1206 Pages 1-59 NEAL R. GROSS AND CO., INC.

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1 2

3 DISCLAIMER 4

5 6

UNITED STATES NUCLEAR REGULATORY COMMISSIONS 7

ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 8

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

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

19 20 21 22 23

1 UNITED STATES OF AMERICA 1

NUCLEAR REGULATORY COMMISSION 2

+ + + + +

3 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 4

(ACRS) 5

+ + + + +

6 ACCIDENT ANALYSIS AND THERMAL-HYDRAULIC SUBCOMMITTEE 7

+ + + + +

8 MONDAY 9

NOVEMBER 2, 2020 10

+ + + + +

11 The Subcommittee met via Teleconference, 12 at 9:30 a.m. EST, Jose March-Leuba, Chairman, 13 presiding.

14 COMMITTEE MEMBERS:

15 JOSE MARCH-LEUBA, Chairman 16 RONALD G. BALLINGER, Member 17 DENNIS BLEY, Member 18 CHARLES H. BROWN, JR. Member 19 VESNA B. DIMITRIJEVIC, Member 20 WALTER L. KIRCHNER, Member 21 DAVID A. PETTI, Member 22 JOY L. REMPE, Member 23 PETER RICCARDELLA, Member 24 MATTHEW W. SUNSERI, Member 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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2 ACRS CONSULTANTS:

1 MICHAEL L. CORRADINI 2

STEPHEN SCHULTZ 3

4 DESIGNATED FEDERAL OFFICIAL:

5 ZENA ABDULLAHI 6

7 8

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3 CONTENTS 1

ACRS Chairman Introductory Remarks 2

Jose March-Leuba 4

3 GEH Overview of NEDC-33912P 4

George Wadkins 5

5 David Hinds................ 12 6

NRC Staff Overview of Safety Review 7

Ryan Nolan

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

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

9:30 a.m.

2 CHAIRMAN MARCH-LEUBA: The meeting will 3

now come to order. This is a meeting of the ACRS 4

Accident Analysis and Thermal-Hydraulics Committee.

5 I am Jose March-Leuba, the ACRS Chairman.

6 Because of COVID-19 concerns, this meeting is being 7

conducted remotely.

8 I see the following ACRS in attendance.

9 Ron Ballinger, Dennis Bley, Charles Brown, Vesna 10 Dimitrijevic, David

Petti, Joy

Rempe, Pete 11 Riccardella, Matt Sunseri. I also know that our 12 consultants, Mike Corradini and Steve Schultz are also 13 present.

14 Today's topic is Topical Report NEDC-15 33912P, BWRX-300 Reactivity Control. This topical 16 report defines the criteria that we'll be using a 17 future submittal to ensure that BWRX-300 reactivity 18 controls satisfy all applicable regulations.

19 Portions of our meeting will be closed to 20 the public to protect proprietary information. We 21 will have an opportunity for public comments before we 22 start the closed session of the meeting.

23 The ACRS was established by a statute and 24 governed by the Federal Advisory Committee Act, FACA.

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5 As such, the Committee can only speak through its 1

published reports.

2 The ACRS section of the U.S. NRC public 3

website provides our chapter, bylaws, agendas, letter, 4

reports and full transcripts for the opened portions 5

of all full and subcommittee meetings. Including the 6

slides presented there.

7 The Designated Federal Official today is 8

Zena Abdullahi. A transcript of the meeting is being 9

kept, therefore speak into the microphones clearly and 10 state your name for the benefit of the court reporter.

11 Please keep the microphone on mute when 12 not being used. And don't use video feed to minimize 13 bandwidth problems.

14 We are expected to have a full committee 15 meeting on this topic in December. At this point, I 16 would like to give the floor to GEH and start your 17 presentation. George, you're on.

18 MR. WADKINS: Good morning. My name is 19 George Wadkins and I am the Vice-president, New Power 20 Plants and Products Licensing for GE Hitachi.

21 Today, GE Hitachi will be presenting an 22 overview of the BWRX-300 small modular reactor design 23 with the description that the content for licensing 24 Topical Report NEDC-33912P BWRX-300 reactivity 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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6 control.

1 We will be describing design requirements, 2

acceptance criteria and regulatory basis for the BWRX-3 300 reactor protection system, or RPS, and other 4

associated means of reactivity control.

5 As noted in our previous discussions with 6

the ACRS Members, the BWRX-300 builds upon our 7

extensive experience in boiling water reactor 8

technology. Including our most recent experiences in 9

development and certification of the economically 10 simple boiling water reactor or ESBWR.

11 The BWRX-300 design leverages the use of 12 proven technology to the greatest extent possible 13 while incorporating advances and design requirements 14 and features to further enhance nuclear safety and to 15 provide for the protection of the public in the 16 unlikely event of an accident.

17 I first want to thank the NRC Staff for 18 their in-depth professional review of this licensing 19 topical report. The interactions with the NRC Staff 20 were extremely useful in ensuring that the content of 21 the licensing topical report was

complete, 22 understandable, accurate and met the applicable 23 regulatory requirements and guidance.

24 I look forward to continuing these 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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7 interactions with the NRC Staff during this ACRS 1

Subcommittee review and the future ACRS Full Committee 2

review plan for December of this year.

3 As previously requested by the ACRS, we 4

are providing for an extensive open session discussion 5

of the content of this licensing topical report, but 6

also have a planned presentation for a closed session 7

later in this meeting.

8 During our presentation we will pause at 9

the end of each slide to allow for questions from the 10 ACRS Member, but please feel free to raise questions 11 at any time. If the discussions involve proprietary 12 information, then we will request saving the question 13 until the latter closed session.

14 CHAIRMAN MARCH-LEUBA: So, let me take 15 advantage of the break and thank you for making such 16 an extensive open session presentation. Obviously, it 17 was very good.

18 And also, know that Member Walter Kirchner 19 has also joined us. Go ahead.

20 MEMBER REMPE: Jose, this is Joy.

21 CHAIRMAN MARCH-LEUBA: Yes, Joy.

22 MEMBER REMPE: Can I ask a question about 23 schedule? When I was reviewing this material I became 24 aware of the fact that the information in section 4.1 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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8 of the LTR we were given is going to change a lot 1

based on the response to an RAI.

2 When will we see, will we see that updated 3

version of the LTR before the December meeting?

4 CHAIRMAN MARCH-LEUBA: I'm going to let 5

the Staff probably handle that, but the process is, 6

notifications that are proved on the RAI, are 7

committed to an RAI, is getting incorporated in the 8

dash A approved version.

9 So, the Staff, can somebody from the Staff 10 handle this question?

11 MS. FRANOVICH: This is Rani Franovich, 12 the project manager for GEH. I just want to make sure 13 I understand the question.

14 Is the question, will the ACRS Members 15 have an opportunity to review the RAIs and the RAI 16 responses?

17 MEMBER REMPE: No, we did see that. And 18 in this case, yes, if it's a small change, yes, we 19 don't usually see it unless, like Jose said, it's just 20 assumed it's going to happen.

21 But it's a substantial difference and I 22 just was wondering, is that going to be the Staff's 23 approach this time, will GE provide an updated version 24 that incorporates this change?

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9 It's in Section 4.1. And I don't want to 1

get into a lot of the details of the change, but it's 2

basically a description of this second independent 3

reactivity control system.

4 And to me that's a, it's quite a bit of a 5

difference and I just am wondering, are we going to 6

see this update at all or is the plan just wait and 7

they're going to send an updated version based on this 8

response and that's it.

9 MS. FRANOVICH: Okay. Thank you for that 10 clarification.

11 If I could suggest that we cover that when 12 the Staff has its turn to present to the ACRS, we'll 13 address it at that time.

14 MEMBER REMPE: Okay, that sounds fine.

15 Thank you.

16 MS. FRANOVICH: Thank you. George, back 17 to you.

18 MR. WADKINS: Okay, thank you, Rani. So, 19 proceeding on to Slide 2.

20 Slide 2 shows the agenda for today's open 21 session presentation. This includes the purpose and 22 scope of the licensing topical report, a discussion of 23 the defense-in-depth strategy forming the basis of the 24 safety assessment framework for the BWRX-300 and those 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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10 related defense-in-depth design features applicable to 1

the reactivity control fundamental safety function.

2 We will also discuss a summary of the 3

design features related to the BWRX-300 reactivity 4

control fundamental safety functions for events 5

requiring use of reactivity control measures for 6

ensuring safety. And we will discuss the regulatory 7

evaluations in demonstrating compliance with the NRC 8

regulatory requirements and conform to NRC regulatory 9

guidance.

10 So, proceeding to Slide 4. Slide 4 and 5 11 will describe the purpose and scope of the licensing 12 topical

report, which includes the design 13 requirements, acceptance criteria and regulatory basis 14 for the BWRX-300 reactivity control design functions.

15 The BWRX-300 has various means of 16 reactivity control. These design functions will be 17 addressed in the LTR by specifying design requirements 18 for the reactor protection system, or RPS, to ensure 19 regulatory requirements are met, specific design 20 requirements for other means of reactor shutdown 21 necessary to ensure that defense-in-depth diversity 22 requirements are met, specified design requirements 23 for other functions, such as alternate rod insertion 24 to ensure the hydraulics scram meets reliability 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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11 requirements.

1 We will discuss the BWRX-300 acceptance 2

criteria and associated mitigating strategy in 3

response to an anticipated transient without scram, or 4

ATWS, as evaluated against the requirements of 10 CFR 5

50.62. And we will describe compliance with the 6

requirements of 10 CFR 50 Appendix in the GDCs 12, 20, 7

21, 22, 23, 24, 25, 26, 28 and 29.

8 We will also describe our regulatory 9

approach for General Design Criteria 27 where we have 10 specified a principle design criteria due to the 11 language of that GDC and how our design approaches 12 these additional means of reactor shutdown.

13 And additionally, as we look at Slide 5, 14 we will discuss the BWRX-300 mitigating systems 15 associated with an ATWS event, anticipated transient 16 without scram. We will specify design requirements 17 for systems to control reactor pressure during an ATWS 18 event.

19 We will specify design requirements for 20 additional means of reactor shutdown. In the case of 21 failure of all means of hydraulic insertion of the 22 control rods.

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12 in response to an ATWS as evaluated against the 1

requirements of 10 CFR 50.62. Are there any questions 2

on the LTR purpose and scope?

3 CHAIRMAN MARCH-LEUBA: No.

4 MR. WADKINS: Okay. I will now turn over 5

the presentation to David Hinds, principle design 6

engineer for the BWRX-300. He will continue 7

describing the non-proprietary contents and 8

conclusions of the licensing topical report.

9 Assisting David, when necessary to answer 10 questions, maybe Lou Lanese, the GEH senior licensing 11 engineer for this licensing topical report, and 12 Charlie Heck, GEH senior consulting engineering, 13 responsible for safety and transient analysis. So, 14 I'll turn it over to David.

15 MR. HINDS: Okay, thank you. Good 16 morning. So this is David Hinds.

17 As was stated a minute ago, I'll just 18 reinforce that we have two slide materials. One for 19 the open session, one for closed session. So, 20 dependent upon the way the questions and discussion 21 go, we may need to defer some topics over to the 22 second session.

23 In this material we covered, I think, most 24 every area but it sometimes is not quite as detailed 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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13 as maybe required. And so, if there is detailed 1

questions we'll likely ask to defer them.

2 Okay. So, the first area, just to give a 3

feel for their GEH design approach we've taken for 4

BWRX-300, not only in this area but across the board, 5

but the slides are focused upon the results obtained 6

in this area.

7 In the area of our defense-in-depth type 8

of design approach. And it's especially pertinent to 9

this topical area to ensure that the means for reactor 10 control and reactivity shut, or reactor shutdown, are 11 maintained and in a defensive type posture of defense-12 in-depth.

13 So, the next slides we'll be walking 14 through will show some of the ways we've laid that 15 out. And we use terminology that comes from the 16 principles developed through the IAEA. So these next 17 few slides use some of that language.

18 We applied defense-in-depth approach. It 19 is aligned with the IAEA principles. We have done 20 some customizing within GEH to develop our process 21 specific to align to that type of approach.

22 We find it very useful to rigorously work 23 our design and our design team through a defensive 24 layer to ensure that the fundamental safety functions 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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14 are maintained with more than one layer. In fact, at 1

least two layers for each postulated initiating event.

2 In some cases we've even had more than two layers in 3

place.

4 So, we evaluate each one of the postulated 5

initiating events. We used the fundamental safety 6

functions. And we assign functions within the design 7

that mitigate in multiple layers.

8 And we ensure those functions when the 9

design is implemented or have the appropriate 10 independence within the design process. So, again, 11 this LTR is focused on that fundamental safety 12 function of reactivity control.

13 Go to the next slide please. Okay. All 14 right, so, the first defense line, within the IAEA 15 terminology is, we've got Defense Line 1, which it 16 really amounts to design approaches and fundamentals 17 within the design to reduce challenges to the reactor 18 protection system, reduce challenges to overall 19 reactivity control.

20 Some of them result in fewer trips per 21 year, so we add reliability features to the plant to 22 minimize the number of trips and the number of 23 challenges to the plant. So, fundamentals begin from 24 those basic approaches.

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15 We strengthen the, all the defense lines 1

through high-quality, reliability conservatisms. So, 2

the Defense Line 1 is a way that we do our design and 3

the fundamentals that apply across the board as 4

opposed to actual physical systems.

5 If you could go to the next slide. Okay, 6

so some of the examples of some of these fundamentals 7

that result in added safety to the plant are, and of 8

course they're common to other reactor designs as well 9

and our past designs.

10 Of

course, technical specifications 11 control the operational controls. We've made many 12 design choices, and I list some of them here.

13 And we have N-Lattice core makes the gap 14 between the control rod, the fuel bundles, where the 15 control rods ride to have less probability of rod 16 binding taken into account. Considerations such as 17 channel bow and potential for degradation or movement 18 in the shape of the fuel channels over the life of the 19 core.

20 And we ensure that we have margins to 21 ensure that we did not create a binding situation.

22 Those are types of approaches that apply to reactivity 23 control.

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16 in this plant. This is a natural circulating power 1

plant so therefore we do not use recirculating pumps 2

to change core flow, and therefore change reactor 3

power. Like some of the, rest of the BWR fleet.

4 So therefore we are constantly, on a daily 5

basis, ensuring the control rods are moving 6

appropriately and controlling the reactor appropriate 7

so therefore no surprises in that, a hidden 8

malfunction in the control ride drive system. And 9

that that's the normal means for power change.

10 We incorporate many reliability features 11 within all of the systems design, with a heavy focus 12 on these associated reactor safety.

13 I alluded to, and I think you are already 14 aware, that this design uses the fine motion control 15 rod drives, which we have experience with through the 16 ABWR fleet development. And we continue to develop 17 through our ESBWR development. And now are carrying 18 forward to BWRX-300.

19 We'll continue to speak more about the 20 design features here in some of the subsequent slides.

21 But the fine motion control rod drives do, that design 22 choice does aid in the reliability of the reactor 23 control fundamental safety function.

24 Okay. Next slide.

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17 CHAIRMAN MARCH-LEUBA: I assume you have 1

some experience with, because this control rod motion, 2

continuous control rod motion to compensate for burn-3 up, what, control areas where there are recirculation 4

pumps, let's see, what do, plays more strain on the 5

fuel, I'm thinking PCI interactions, better planning?

6 MR. HINDS: So, a couple of comments on 7

that. This core, and again, in this Defense Line 1 8

area it's design decisions, and you've alluded to 9

another.

10 So, we made design decisions to 11 intentionally re-limit the power density of this 12 plant. So, we've made design choices on core design 13 to not push it to achieve all the power that we could 14 potentially achieve out of the core of this size.

15 So, limiting the power density, making 16 design decisions on the actual fuel load. And the 17 number of fuel bundles, we did optioneering, we called 18 it, of how many fuel bundles would this core contain.

19 Our final selection was, much of it was 20 based upon ensuring that we limit fuel duty. So, we 21 have looked heavily at fuel duty and mechanisms such 22 as PCI.

23 So, do not think it's going to be a 24 problem, in brief summary. Some other --

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18 CHAIRMAN MARCH-LEUBA: And you're not --

1 MR. HINDS: Yes.

2 CHAIRMAN MARCH-LEUBA: You're not already 3

planning for a power uprate, are you?

4 MR. HINDS: No, we're not.

5 CHAIRMAN MARCH-LEUBA: Not yet.

6 MR. HINDS: Our intention is, that we 7

selected the appropriate power level for this plant.

8 And that was part of our optioneering.

9 But we did it, again, in a very 10 conservative fashion knowing that control rods are the 11 normal means of maneuvering the plant. And so, we did 12 limit our priorities.

13 But no, we did not plan for a power 14 uprate.

15 CHAIRMAN MARCH-LEUBA: Okay, thank you.

16 MR. HINDS: Okay. So, other design 17 choices we've made that help with the conservatism and 18 safety of the plant, of course, seismic qualification.

19 This is all design with a high seismic margin.

20 I mentioned the FMCRDs. We did have the 21 operating experience with ABWR, continued to design 22 the experience with ESBWR.

23 Control rod blades, we have extensive 24 experience through the operating fleets that we 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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19 understand all the details of their behavior and the 1

way to manufacturer.

2 And so we've been through generations of 3

control rod blades. And we carry that forward to the 4

BWRX-300.

5 And I think we've mentioned it in one of 6

our prior meetings, but we are using the same fuel and 7

control rod blades that we've been advancing through 8

our operating fleet. So the length of the fuel bundle 9

is our standard GNF2 fuel and therefore the standard 10 control rod blade. So therefore it's not a first of 11 a kind development that we bring with it some sort of 12 questions.

13 And just list that many years of 14 experience with, up to and including, the ABWR, 15 although some might think it's a new plant, it's got 16 years of experience. And there is multiple plants 17 that have operated in Japan. Okay.

18 DR. SCHULTZ: David, this is Steve 19 Schultz.

20 MR. HINDS: Yes.

21 DR. SCHULTZ: Question. You mentioned on 22 the previous slide that there are reliability 23 improvements associated with a fine motion control rod 24 drive. And here you talk about the experience that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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20 you've gained from the other unit designs.

1 Anything in particular that has improved 2

the reliability of that system, over and above, what 3

you've seen before in your operational experience?

4 MR. HINDS: We have some plans where, 5

depending upon the level of detail I might need to 6

revert to the second segment of this. But we have 7

made some changes to our motor selection.

8 We have gone through a series of coupling 9

designs and coupling selections. And related to the 10 motor selection it also determines the capability of 11 how fine of a movement.

12 If it's okay with you, I'll come back to 13 this and maybe highlight a few other features when I'm 14 showing some visuals in the second segment. And 15 please, if I didn't adequately address your question 16 at that time please readdress it. But I wrote a note 17 for myself, I'll bring up again.

18 But

again, primarily in the motor 19 coupling, we've also gone through into the bearings 20 and looked for material reliability. But I'm not 21 stating that we have a reliability problem with the 22 current fleet of FMCRDs, we just continually look to 23 advance and learn.

24 DR. SCHULTZ: I understand. Thank you 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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21 very much. I look forward to your further remarks.

1 MR. HINDS: Okay, thank you.

2 CHAIRMAN MARCH-LEUBA: I have lost the 3

slides. Oh, there they are.

4 MR. HINDS: Yes, they dropped off for a 5

second, sorry. Okay, continuing through our defense 6

line type of defensive measures.

7 Now, once we get beyond Defense Line 1 and 8

we get into mitigating systems and features, more into 9

what we typically look into systems.

10 So, in Defense Line 2 includes functions 11 which would normally control the plant. We do have 12 added levels of quality for those systems, although 13 they're not using the U.S. terminology, safety 14 related, but using international terminology, they are 15 Safety Class 3.

16 So we do apply a higher degree of controls 17 upon design and procurement. And so we do get some 18 credit for safety, but it's only one layer. Defensive 19 layer.

20 They play a large role in limiting and/or 21 preventing a postulating and initiating event. And 22 they minimize postulated initiating events, I'm sorry 23 if I did this on the acronym PIE, that reach Defense 24 Line 3 set points.

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22 Defense Line 3 is that layer right in the 1

heart of safety, which is what, in U.S. terms, would 2

be safety related or in international terms, safety 3

class 1. So Defense Line 2 is a front-line defensive 4

layer to prevent challenges to the core of the safety 5

of the plant.

6 But we have a high focus and an elevated 7

focus on that layer in this plant, which is one of the 8

things that we've done to add a more defense-in-depth 9

type approach to this plant.

10 If we can go to the next. And so I'll 11 show you --

12 CHAIRMAN MARCH-LEUBA: So would you say 13 that this is the control system that is non-safety 14 grade that prevents the accident, the initiated events 15 from getting worse, is that correct?

16 MR. HINDS: That's a correct statement.

17 And they additionally will minimize the number of 18 initiating events because, historically, many of the 19 postulated initiating events originated in what we're 20 now calling our Defense Line 2, or Safety Class 3 21 systems.

22 Things like the feedwater control system.

23 So, feedwater level control system is a Defense Line 24 2 system. And it is a potential initiator. And it 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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23 also helps to limit other related initiators.

1 CHAIRMAN MARCH-LEUBA: So, what really is 2

the alliance is, because you plan to use digital 3

controls, computer controls, you can do more than an 4

analog controller?

5 MR. HINDS: Right.

6 CHAIRMAN MARCH-LEUBA: Okay. If the 7

feedwater is fast running away, you can create some 8

safety functions inside a controller that would bring 9

it back.

10 MR. HINDS: Yes.

11 CHAIRMAN MARCH-LEUBA: Which you couldn't 12 do with an analog controller.

13 MR. HINDS: Yes. We would --

14 CHAIRMAN MARCH-LEUBA: Good.

15 MR. HINDS: Your statements are correct.

16 We're using digital controls. And our defensive 17 layers are separated digital controls.

18 So the Defense Line 2 is separate from our 19 Defense Line 3 and so therefore if you go down the 20 path, common cause failure, it's not, it will add a 21 defensive layer, as well as the capabilities of 22 technology advance, as you had just mentioned, help as 23 well.

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24 like a rod connector. It makes sense.

1 MR. HINDS: Okay. And we have, the really 2

nice thing about our Defense Line 2 and those systems, 3

we, again, picture high quality systems, we call 4

Safety Class 3, and we apply high reliability features 5

such as a selection of a triplicated controller versus 6

just a simple singular controller. And those features 7

add significant reliability to the plant.

8 I'll go more into the details of what's in 9

Defense Line 2. These are kind of high-level terms.

10 And some of those details will be in the next segment, 11 so if you don't mind, I'll do some higher level 12 introduction here and then revisit it again later.

13 MEMBER BLEY: Just to interrupt a second.

14 MR. HINDS: Yes. Please do, yes.

15 MEMBER BLEY: This is Dennis Bley. I 16 don't really want to dig into it here but I'm guessing 17 that when we get the reviewing I&C we'll dig into this 18 Defense Lines 1, 2 and 3 business. If that's true, 19 that's fine.

20 If it's not, maybe you can give us more 21 detail in what you mean by, they are separate from 22 each other. That can mean lots of different things.

23 And how separate are they on the different 24 counts, just electrically or by communication? So, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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25 I'm happy to put this off to I&C, but if it's not 1

going to be there, maybe you can talk more about it.

2 MR. HINDS: Okay. We'll do both. I'll 3

touch it again in our next segment, in the second 4

portion of our presentation in closed session, and 5

then you'll also see it again whenever you see I&C 6

submitted for that portion of licensing. So we'll hit 7

them both.

8 But in simple summary, they're quite 9

separate. But I will get back to it in the second 10 segment of this. I understand your question.

11 MEMBER BLEY: Okay, thanks.

12 MR. HINDS: So, control power generation 13 systems, they, again, limit and mitigate events. I'll 14 touch more on this in the later segment.

15 In Defense Line 2 we also mitigate 16 incorrect rod potential, postulated incorrect rod 17 movements, with rod blocks.

18 George, if you can go to the next slide 19 please. Okay, Defense Line 3 is the heart of safety, 20 as I mentioned. It's what, in U.S. we've used the 21 term safety related, internationally we call Safety 22 Class 1.

23 We include functions that mitigate the 24 postulated initiating event. We ensure the plant is 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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26 placed in a safe state, such as a reactor scram. We 1

assign the highest safety class and the highest 2

procurement controls and design controls.

3 And a little bit to your question a minute 4

ago, they are independent of Defense Line 2. I'll 5

keep building on that.

6 Okay, George, next. Okay, so, we, within 7

the BWRX-300 it is a passive safety natural 8

circulating power plant. Hopefully our introduction 9

from a prior ACRS meeting will carry forward to now.

10 I didn't include an overall summary of the 11 BWRX-300 but I'd be glad to revisit anything if there 12 is questions.

13 However, in Defense Line 3, functions 14 associated with reactivity control of interests are 15 the reactor protected system and the associated scram 16 features that implement, that are implemented, or 17 actuated by the reactor protection system, the 18 isolation condenser system for heat removal.

19 Those are key, Defense Line 3, Safety 20 Class 1 or safety related systems and functions that 21 we contain within Defense Line 3.

22 George. Okay. Then the backup, or 23 Defense Line 4 --

24 MEMBER BROWN: Excuse me for a minute.

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27 This is Charlie Brown.

1 MR. HINDS: Sure.

2 MEMBER BROWN: Looking through your 3

Defense Lines 1, 2 and 3, I'm the I&C person, 4

representative. Along with Dennis, and anybody else 5

that wants to participate in that area.

6 I was trying to get a handle on the 1, 2 7

and 3. It appears to me that Defense Line 3 is where 8

your classic reactor protection system is called on.

9 And it's the last, I view that as the last line of 10 defense.

11 So the Defense Line 1 and 2, I presume are 12 based on what you've been saying, sound like 13 refinements of your operations and control functions 14 that minimize the likelihood of having to have an 15 automatic reactor protection system response. Am I 16 reading what you're talking about correctly?

17 MR. HINDS: I think most, if not all of 18 your statements, are correct. I'd like to amply on 19 them some in our second segment if --

20 MEMBER BROWN: That's fine.

21 MR. HINDS: -- that's okay?

22 MEMBER BROWN: Yes, that's fine. Thank 23 you.

24 MR. HINDS: Yes. Defense Line 3, in brief 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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28 summary, Defense Line 3 is the hardest safety and that 1

is the traditional and fundamental reactor protection.

2 But we looked on both sides of that in the front end.

3 In order to minimize challenges to it, 4

we've added features. And then on the back end, in 5

case we reach low probability failures, set of complex 6

sequence with common cause failure, for example, we've 7

got some backup features. So that's where we are now 8

with this, up to Defense Line 4.

9 MEMBER BROWN: Okay.

10 MR. HINDS: So, Defense Line 4 we've 11 segregated into 4A, 4B. And the 4A includes functions 12 to mitigate postulating initiating events that occur, 13 that postulate occur, and a subsequent postulate 14 failure of the safety related systems to mitigate 15 them.

16 So, a

very

complex, low frequency 17 occurrence. We plan for them as well to mitigate the 18 common cause failures that, CCF acronym, in Defense 19 Line 3 and ensure plant is in a safe state.

20 Next. So, related to reactivity control, 21 examples of Defense Line 4A, so this would, we'd never 22 go here unless we have a common cause failure, so they 23 arise. An example, alternate rod insertion. It 24 provides the hydraulic scram in event that the HCUS 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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29 fail to actuate.

1 We also have another means, because of our 2

design selection way back in Defense Line 1 of our 3

design selection of fine motion control at drive, we 4

have motors in addition to the hydraulics. So it 5

allows another means for the control rods to be 6

inserted.

7

Again, I'll keep revisiting these 8

features. So I'm trying to buzz through a little now 9

and then I'll come back and I'll catch all the 10 questions, I hope.

11 MEMBER BALLINGER: This is Ron Ballinger.

12 I'm assuming, I guess the way I read it, this ARI is 13 a substitute for SLIC?

14 MR. HINDS: Well, ARI provides another 15 means to ensure that the reactor is shutdown. So, in 16 a way I guess you would be correct.

17 So, sure, it's another means for reactor, 18 to ensure the reactor is shutdown. We have, and I'll 19 keep building upon this because some of these we 20 protected are the materials so I won't open so 21 detailed right now but I'll keep revisiting and 22 reinforce that. I wrote a note on that one as well.

23 DR. CORRADINI: So, this is Corradini.

24 I'm with Member Ballinger. I'm a little confused 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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30 here.

1 So, if we go to closed session to explain 2

this, I guess I'd like some clarification as to what 3

the ARI is in difference to what has been common in 4

BWRs and the ESBWR, the SLIC.

5 MR. HINDS: Okay. I'll start answering it 6

and then I'll finish answering in the closed session, 7

if that's okay.

8 But you're correct in, I think, your 9

statement that ARI was used on past BWRs. So that 10 statement is correct.

11 But there are some added features on the 12 BWRX-300. And I'll build upon them as we go.

13 MEMBER BALLINGER: So this is Ron 14 Ballinger again. So I'm assuming that we'll get, at 15 some point, to the PRA later on in time, I guess, and 16 that the alternate rod insertion scheme will have a 17 significant effect on the PRA?

18 MR. HINDS: Yes. It is impactful on the 19 PRA, that is correct. All of these layers have an 20 impact on the PRA.

21 We've done initial, and to your point on 22 PRA, we've done the initial PRA. We did not have the 23 final PRA so we're not as prepared to submit a PRA at 24 this stage. But we do have our initial PRA. And we 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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31 continue to use the PRA in parallel with design 1

progression.

2 And you're correct that these features do 3

impact the PRA. I mean, there's a whole layer in the 4

layered failure.

5 MEMBER BALLINGER: Yes. In addition to 6

that, I keep hearing the word, increased reliability, 7

inserted more reliable this, more reliable that.

8 I'm assuming that when we get to the PRA 9

you'll have some kind of data which supports, that 10 puts a number on that.

11 MR. HINDS: Yes, that's our intention.

12 Now, yes, within the PRA approved methodologies.

13 That's correct.

14 MEMBER BALLINGER: Thank you.

15 MEMBER REMPE: So that was actually the 16 question I had, was related to the data. Do you have 17 the data or is it envisioned you're going to have to 18 obtain additional data when you come in with 19 additional documents related to this plant?

20 By the time you do a DCA or a Part 50 21 application, will have to obtain additional data?

22 MR. HINDS: And I assumed you were talking 23 about failure. Failure rate type data that's used 24 within the PRA, I assume, based upon your question.

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32 MEMBER REMPE: Yes, that. And then I 1

thought there was some also thermal hydraulic features 2

with this plant that were a bit different that I was 3

wondering if there was going to be some sort of 4

testing program to demonstrate them. These features.

5 MR. HINDS: Yes. But we have a detailed 6

thermal hydraulic analysis within our TRACG model.

7 And as we get into the second segment, if 8

you want to go deeper into that, Charlie Heck is on 9

the line who's our expert on that. But yes, we have 10 been doing detailed thermal hydraulic analysis using 11 our TRACG computer code.

12 And we additionally are doing PRA analysis 13 for our frequency of N sequences and the frequency of 14 occurrences.

15 MEMBER REMPE:

So, in

those, the 16 reliability in the thermal hydraulics, I'm hearing you 17 saying you're doing analysis. But did you have to 18 obtain any additional data or do you need to obtain 19 additional data, is what I was curious about?

20 MR. HINDS: So, for the thermal hydraulics 21 we have been benchmarking for years with the operating 22 fleet. And that data is pertinent to the BWRX-300.

23 We also have some additional previous task 24 data for test facilities that we've also used for 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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33 benchmarking. But we did not envision the necessity 1

for further testing. It doesn't mean we won't do 2

testing, but we do not see the necessity for further 3

thermal hydraulic testing.

4 MEMBER REMPE: Okay. Of reliability 5

testing, so you think the data you have is adequate to 6

support these changes in this design? Is that what 7

you're telling me?

8 MR. HINDS: Yes. It doesn't mean we won't 9

do further confirmatory, but that's what I'm telling 10 you.

11 MEMBER REMPE: Okay, thank you.

12 MEMBER BALLINGER: But the alternate rod 13 insertion system is new?

14 MR. HINDS: The alternate rod insertion is 15 used in the existing fleet. Now, it's not a system 16 that's called upon because it's a deep defensive 17 layer, even on the existing fleet.

18 But the alternate rod insertion is used in 19 the current BWR fleet. It's an alternate means of 20 depressurizing the scram air header in the case of 21 some sort of failure within the HCUS.

22 MEMBER BALLINGER: Oh, but this, look, 23 okay, now I guess I'm demonstrating my ignorance.

24 This ARI system, sorry for the phone, I 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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34 can't shut the darn thing off, the alternate rod 1

insertion system, in this case, would be called upon 2

to operate in a different way?

3 MR. HINDS: It is quite similar to the, 4

that one feature is quite similar to the existing 5

fleet. And that feature, again, is to, in the case we 6

postulate many different failure modes for the reactor 7

scram.

8 And one of the potential failure modes, 9

not probably, but potential, is the failure of the 10 hydraulic control units to reposition and allow the 11 high pressure water to insert, hydraulically, to 12 control rods.

13 If that were to occur, we'd have the means 14 to depressurize the scram air header, which causes the 15 HCUS to reposition in an alternate way.

16 CHAIRMAN MARCH-LEUBA: Right. I believe 17 you have a diagram on the closed slides, which would 18 be --

19 MR. HINDS: That is correct.

20 MEMBER BALLINGER: Yes.

21 CHAIRMAN MARCH-LEUBA: -- a better time to 22 address it, because we're running late guys.

23 MR. HINDS: Okay.

24 CHAIRMAN MARCH-LEUBA: You have only 15 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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35 minutes.

1 MR. HINDS: Okay.

2 CHAIRMAN MARCH-LEUBA: And we are running 3

proprietary information. So keep going.

4 MR. HINDS: Oh, sorry. Thanks so much.

5 Okay, we'll I'll keep moving, and we'll get back to 6

your questions. I've got many notes here.

7 So, Defense Line 4B is our deep defensive 8

layer. We call it things such as FLEX, just to get 9

you a realm of, when we, if we were, we even do 10 postulate transition into extreme events or severe 11 accidents, and that's where we enter that 4B.

12 We really do not features to highlight 13 today in this topical report related to 4B. I'm just 14 letting you know the big picture.

15 So if we could keep going please. Okay.

16 All right, could you advance, George. Okay. Okay, 17 keep going.

18 Okay, so we did show some visuals in this 19 non-proprietary segment. These are visuals that we've 20 previously shown, but we have some others in our 21 proprietary version that we did not include in this 22 segment.

23 But just to give a little quick intro, and 24 to more of the designs we're talking about. This is 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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36 just a visual showing the control rod blades.

1 And the control rods are positioned in-2 between the fuel bundles, four fuel bundles in a cell.

3 And that's where I was talking about we have ample 4

space for these control rods to move within these fuel 5

bundles. Just a quick introduction. Next.

6 CHAIRMAN MARCH-LEUBA: Is this drawing on 7

the right to scale that shows that much clearance 8

between the rod, between the blade and the bow?

9 MR. HINDS: I'm now sure, I'd have to 10 double check. It's not bad but it's, this is a 11 PowerPoint presentation so I cannot claim that it's to 12 scale.

13 CHAIRMAN MARCH-LEUBA: Okay. It's not to 14 scale but close. Keep going.

15 MR. HINDS: Yes, I think it's a reasonable 16 representation, but I can't claim it's to scale.

17 Okay. This is just showing, this is the 18 top view of the core. So it's just showing, just 19 giving you a big picture here.

20 We have many control rods. So, basically 21 you have 57 control rods in this core. And so, even 22 if one, or even more were to fail, we'd still have 23 ample means to control reactivity of this core.

24 Okay. GNF2 fuel I mentioned before. So, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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37 our proven fuel.

1 I've already mentioned several of these 2

topics here, but again, we have much experience with 3

the fine motion control rod drives, it's not just a 4

brand new invention.

5 It does, they do operate by hydraulic 6

force for scram. And normal movement, day in, day 7

out, is with the fine motion motors.

8 So, there is hydraulics that insert 9

rapidly in the case of the need for a scram, and there 10 is motors that move in day in and day out. The motors 11 provide a fine means of control, but they also provide 12 diverse needs of insertion.

13 The ARI that we mentioned previously is a 14 diverse means to actuate the hydraulics. Again, we'll 15 show you the figure in a little while, as was 16 mentioned.

17 Some might be familiar of the history of 18 the BWRs where we've been using hydraulics for a long 19 time for control rod movement. But the hydraulics on 20 the older plants that did not have motors attached to 21 the control rod drives, they have a scram discharge 22 volume as well.

23 So they have a hydraulic side on both 24 sides where the, on this, the hydraulics to insert is 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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38 all that's applied, there are no hydraulics for 1

withdrawal.

2 And so, in the previous locking piston 3

control drives, which are still successfully in 4

service in the fleet, there is a scram discharge 5

volume which allows for an exhaust on the top side of 6

the piston. That is not present in the BWRX-300, or 7

in any of our FMCRDs.

8 There are some failure modes that we've 9

combated over the years with our scram discharge 10 volume. Elimination of that scram discharge volume 11 eliminates a potential failure mode of the hydraulics.

12 So I'm just mentioning that from the 13 standpoint of another of, I've been saying these 14 words, increased reliability. That's one way of 15 increasing reliability of the hydraulics. And then we 16 additionally have diversity and redundancy.

17 Okay, George.

18 MEMBER BLEY: So, David, that implies 19 there is an open release pass for where the scram 20 discharge volume needs to be, is that right?

21 MR. HINDS: Yes. It basically just goes 22 into the reactor vessel.

23 MEMBER BLEY: Okay.

24 MR. HINDS: So it's a one-way path. You 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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39 push it in and the water has enough flow by internals 1

in the FMCRD to go into the reactor vessel.

2 Okay. So, just a related, but a little 3

different, this is just the cut away of the reactor 4

pressure vessel. It is, because it's the natural 5

circulating plant, we alluded to this in our, or we 6

covered this in our first LTR, which we previous 7

presented.

8 But the large volume, or relatively large 9

volume, for the purpose of natural circulation had 10 advantages of, that steam volume allows for a lower 11 pressurization rate in events. And, again, we 12 covered, I've listed the reference of the previous 13 LTR. I won't go into details here since we've already 14 covered.

15 Okay, George. And we've also covered this 16 in our prior LTR but I'm mentioning it again because 17 it is pertinent to mitigating failures within 18 reactivity control.

19 Because, one, important for removing the 20 energy of the reactor, of course is to shut it down, 21 but then, this is the key system to, and this is a 22 very, very simplified visual. So there are, this is 23 not the, as designed, this is just to show your visual 24 representation of the isolation condenser system which 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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40 is our Safety Class 1 safety related heat removal 1

system.

2 So, in the event of an isolation event, 3

the energy is removed by the isolation condenser 4

system by taking steam condensing in pools. Similar 5

to the design that was implemented on the ESBWR, and 6

then returned the condensate back to the reactor 7

vessel, limits reactor pressure and provides for a 8

passive means of cooling.

9 Once actuated, no further means for any, 10 there's a valve that has to open to open the flow 11 path. And once actuated, it needs no further support 12 system other than just that pool that heat exchangers 13 are immersed in.

14 Okay.

15 MEMBER REMPE: So this --

16 (Simultaneous speaking.)

17 DR. CORRADINI: This is Corradini.

18 CHAIRMAN MARCH-LEUBA: Okay, Mike.

19 DR. CORRADINI: I guess maybe we should 20 wait till the closed session, just so you can confirm 21 it, but I have a number of questions about this 22 cartoon, so, since it's a cartoon should we wait till 23 closed to ask detailed questions?

24 MR. HINDS: If it's okay, that would be 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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41 great. Because we're running a little behind.

1 DR. CORRADINI: Okay, I'll wait then.

2 I'll wait.

3 MR. HINDS: Great. Thank you.

4 MEMBER REMPE: So I have one quick 5

question though. Is the water level, this water level 6

differs from what we were shown in the open sessions 7

or closed sessions in prior discussions of this plant.

8 Is the water levels substantially above 9

where the piping is?

10 MR. HINDS: Yes. The water level, meaning 11 the piping, meaning the condensate return? Yes.

12 MEMBER REMPE: Right. Because that's, 13 thank you.

14 MR. HINDS: I'll get back to that in the 15 closed session. In case I didn't answer your 16 question, please ask again in the closed session.

17 CHAIRMAN MARCH-LEUBA: Yes. One thing you 18 didn't mention is the size of the ICS. We mentioned 19 in the previous, this is grossly over designed?

20 MR. HINDS: It's a large system, yes.

21 It's got a large capacity. So yes, it's capable for 22 controlling reactor pressure.

23 CHAIRMAN MARCH-LEUBA: Okay, thank you.

24 MR. HINDS: Okay. Okay, so just a brief 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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42 mention, and I think the NRC will cover in more 1

detail, possibly, on the regulatory side of the 2

review. And, George or Lou, if you have anything to 3

interject please do.

4 So, some of the associated regulations and 5

regulatory guidance that we covered in this licensed 6

topical report, of course, there is 10 CFR 50.62 for 7

the ATWS event.

8 And we just highlight a point here that 9

the, the ATWS rule was written at a time when these 10 multiple defense-in-depth features, that I was 11 describing and just giving a brief intro here, were 12 not all present.

13 And so we feel that the, and I also 14 alluded to reliability, you asked me about, that the 15 added defenses, defense line features that we have 16 implemented with BWRX-300 will result in a lower 17 frequency of occurrence of that postulated event 18 sequence, complex sequence of an ATWS. So, things 19 have changed significantly.

20 And even with the older designs we were, 21 the statement here from the NUREG 1780, which we read 22 to study the history, found that even with the 23 previous designs don't include some of the features 24 that I described. We even met the reliability goals, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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43 as stated in the intent of the ATWS rule. So just a 1

little background, okay.

2 George. All right. And here is some 3

review guidance that we also referenced. I know its 4

review guidance, but we referenced it to help align 5

with the expectations.

6 In the SRP 15.8 there is statements about 7

evolutionary plants, which this plant is. Then we 8

will tell you some more in the closed session about 9

diverse features, so I'm just highlighting that point 10 that in the SRP there is some mention of, and that a 11 mitigating strategy could be to add diverse features.

12 Again, we protected some of the details of 13 our diverse features. I just briefly introduced them.

14 We'll come back to them, but we do have diverse 15 features in this plant is really the point I'm trying 16 to get at.

17 Okay. We do have alternate means for 18 shutdown. We do have alternate rod insertion, which 19 is explicitly called out in the rule.

20 We do have electric motors to insert the 21 control rods that are independent of the hydraulic 22 insertion method. We do have multiple means of 23 shutting down the plant.

24 And we have evaluated even failures of 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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44 those in each of our defense line type of approach.

1 If a failure occurs in one defense line or a failure 2

occurs in multiple defense lines.

3 Okay. So we, 50.62 mandates reduction of 4

risk from an ATWS. We think we have done that. And 5

we will continue to supply information to further 6

prove that, such as what was asked a little while ago, 7

is about the PRA.

8 During a license submittal for a plant, we 9

would submit the PRA as expected. And if it proves 10 out that we have reduced the risk of an ATWS as called 11 out by this rule.

12 They require ARI. I mentioned before we 13 have it. Require SLC, we'll cover further in a little 14 while. And requires automatic recirc pump trip.

15 Okay, George. Okay, so, I've already 16 mentioned most of this. Each control rod contains 17 certified hydraulics. And the hydraulics can also be 18 actuated by its normal means, but also actuated 19 mechanically by the ARI.

20 Also, the motors, I've mentioned several 21 times, provide a diverse means for insertion. We 22 think those are key features for evaluating the ATWS 23 rule.

24 We also have diversity and separation 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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45 between the control systems associated with the normal 1

means of scram and the alternate means of scram.

2 Eliminates common mode failures by having 3

these diverse means. Or eliminates at least having 4

the effects of the common mode failure of inability to 5

shut the plant down.

6 And I

already mentioned the scram 7

discharge volume was removed, so that failure mode is 8

an example of one that was just completely removed.

9 SLC, we eliminated the failure of control 10 rod insertion from a single common cause failure so we 11 used a defense-in-depth approach. We'll talk a little 12 more about, more details associated with SLC because 13 we had that in the second session. Okay.

14 CHAIRMAN MARCH-LEUBA: Dave. No, go back 15 to the Slide 30.

16 That statement, I don't see you have 17 eliminated the failure. What you can say is that we 18 have looked very hard and haven't found, found one 19 yet.

20 MR. HINDS: Okay.

21 CHAIRMAN MARCH-LEUBA: Do you agree on 22 that?

23 And in light of that it is a little 24 unclear to me when I read everything, whether we plan 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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46 to claim that the probability of ATWS is so small that 1

we don't have to worry about it. Are we going to 2

analyze it and demonstrate that nothing breaks? Within 3

the relaxed ATWS criteria, which are very relaxed, 4

basically comparability.

5 Because one concern I have is ATWS over 6

pressure. There are some special features that the 7

pressures in ATWS might, it still needs to be 8

calculated.

9 MR. HINDS: Yes.

10 CHAIRMAN MARCH-LEUBA: So what is your 11 path, A or B?

12 MR. HINDS: So, let's see if this at least 13 partially addresses your question. And again, part of 14 our details of thermal hydraulics we had planned for 15 the segment, as needed.

16 But we did analyze failure of the normal 17 scram system and the associated reactor and pressure 18 transient that occur as a result of failure of the 19 normal scram system.

20 We did, in that analysis, credit some of 21 the diverse means as mitigation. But we did analyze 22 the pressure response and have acceptable results to 23 the pressure response on the failure of the normal 24 scram system.

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

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47 DR. CORRADINI: I'm, this is Corradini, 1

can you repeat that, I don't think I appreciate what 2

you just said?

3 CHAIRMAN MARCH-LEUBA: Yes, I was going to 4

suggest, and it was me, let's delay this till the 5

closed session because we have to talk about this, 6

especially mitigation features and all that.

7 MR. HINDS: Okay. Yes, I think that's, I 8

would appreciate that.

9 CHAIRMAN MARCH-LEUBA: Yes.

10 MR. HINDS: Okay. Thank you. I 11 understand your question.

12 Okay, so I mentioned this but I this is, 13 hopefully, an easy one. But this plant has no 14 recirculating pumps. No recirc pumps.

15 It's a natural circulating power plant so 16 the prescriptive rule for tripping the recirc pumps is 17 not technically relevant to the BWRX-300. However, we 18 do consider what was the fundamental purpose of doing 19 that in reducing the overall reactivity.

20 And we have other features for ensuring 21 that we reduce the reactivity. But we do not have 22 recirc pumps to trip.

23 CHAIRMAN MARCH-LEUBA: And this is 24 probably for the staff. In something as obvious as 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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48 this that clearly is not applicable, do we need an 1

exemption because the recirculation pump trip is 2

easily called up in the rule.

3 So does this have a mechanic, a proceed 4

here that I think is obvious what the answer is. But 5

maybe I'll ask the Staff whether we need an exemption 6

from 50.62.

7 MR. HINDS: Okay. Would you like for me 8

to keep proceeding and wait for the --

9 CHAIRMAN MARCH-LEUBA: Yes, please.

10 MR. HINDS: -- Staff's presentation or --

11 CHAIRMAN MARCH-LEUBA: Yes. Yes, go 12 ahead.

13 MR. HINDS: Okay, thank you. Okay, so, 14 again, we'll talk some more, as you just mentioned, 15 about the analyses results in our next segment. But 16 we did use the regulatory acceptance criteria from the 17 rule and from the regulations. And we just listed 18 some of them here.

19 Nothing we've changed anything here, it's 20 just restating some. So, if you have questions or 21 would like me to elaborate, please let me know.

22 Otherwise we're just recognizing that we understand 23 and will maintain the regulatory acceptance criteria.

24 Okay, George. So into the general design 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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49 criteria level. So, within GDC27 we did, because of 1

the wording of the GDC, we did have some proposed PEC.

2 And that's included in the LTR. It's related to our 3

means of reactivity control during a failure to scram.

4 But we do maintain core coolability. And 5

there is just this portion related to pose an addition 6

by ECCS. It's not relevant to this plant and that's 7

what resulted in the PEC. I think we have more slides 8

on this but --

9 MR. WADKINS: Yes, later.

10 MR. HINDS: Okay. Then we'll come back to 11 that a little bit later. And I think the Staff will 12 cover some as well.

13 MEMBER REMPE: So, at this point, Jose, 14 I'd like to come back to my very first question.

15 I've heard that there is a September 2020 16 version of this LTR that's been with the, had the 17 revisions from the RAIs incorporated.

18 MS. FRANOVICH: That's correct.

19 MEMBER REMPE: We only have the March 2020 20 version of it. And that's a shame but since we've 21 been given the March 2020 version, can we be provided 22 the September 2020 version, not only the clean copy 23 but also some way that shows track changes so we don't 24 have to go through and re-review everything?

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

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50 But I just think that the changes were 1

sufficiently substantial. That it would be good for 2

us to see how it is cast at this time.

3 MS. FRANOVICH: This is Rani Franovich, 4

the project manager. In the SE the Staff wrote an 5

introduction that explained that there was a

6 supplement to the original SE that was provided on 7

September 4th, 2020.

8 The accession number is provided in the 9

introduction. We do not have a track changes version, 10 but there is, in the document that was submitted by 11 GEH, a table, as I recall, that described the changes 12 that were made.

13 George, can you confirm that?

14 MR. WADKINS: Yes, that is true. The 15 Supplement 1 does have a revision record which 16 explains the changes. They were, I believe in this 17 supplement, they were entirely from that one set of 18 RAIs.

19 MEMBER REMPE: So, please get that to Zena 20 and have her, she'll distribute it to us soon because 21 we, I missed it that this Supplement 1 existed. And, 22 again, I just checked our share point site, we only 23 have the March 2020 version out there.

24 MS. FRANOVICH: Understand.

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

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51 MEMBER REMPE: Do you have the September 1

version, Jose?

2 CHAIRMAN MARCH-LEUBA: No, I don't. I 3

know you asked this last week, or two weeks ago, and 4

I was not aware.

5 MEMBER REMPE: No. Okay, so please get 6

that to us. Thank you.

7 MR. WADKINS: Okay, thanks, David. If 8

there are no further questions then I wish to thank 9

the NRC Staff once again and the ACRS Members for 10 their time.

11 We will discuss some of these items that 12 we tabled in the closed session. But again, if there 13 are no additional questions we will turn this over to 14 the NRC Staff to present their SER.

15 MS. FRANOVICH: Okay. Thank you, George.

16 I'm going to share my screen. And if I could get some 17 feedback that you guys, everyone can see it, that 18 would be great.

19 CHAIRMAN MARCH-LEUBA: We can see the 20 screen, but the slide is all garbled. You need to put 21 the slides on top.

22 MS. FRANOVICH: I'm trying to, I'm trying 23 to do that as we speak. Bear with me. Huh. Can 24 everyone see that?

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

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52 CHAIRMAN MARCH-LEUBA: Yes. Now it's 1

perfect.

2 MS. FRANOVICH: Thank you. All right, 3

Ryan, I will turn this over to you to start the 4

Staff's presentation.

5 MR. NOLAN: Thank you, Rani. This is Ryan 6

Nolan. I am in NRR in the Nuclear Methods Systems and 7

New Reactor Branch and I will be presenting a brief 8

overview of our safety evaluation in the open session.

9 A lot of the underlying material in which 10 we made our findings is based on proprietary 11 information, so a good portion of our discussion will 12 have to be in the closed session.

13 Rani, you can go to the next slide. So, 14 in this presentation I'm going to briefly go over who 15 the review team was, a brief background on the BWRX-16 300, as well as our review of NEDC-33912 and then I'll 17 wrap up with our conclusion.

18 So, in addition to myself, my colleagues 19 Andrew Proffitt and Alex Siwy will be co-presenting in 20 the closed session with me.

21 And we also had some support from 22 additional tech staff and other disciplines who are 23 available to answer any questions that come up in 24 their area. However, there is no specific slides.

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

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53 And I'll address that when we get there.

1 Rani, you can go to the next slide. So, 2

a very brief background. The BWRX-300, it's a 300 3

megawatt electric SMR, uses natural circulation.

4 Passive cooling is provided by the isolation condenser 5

system and it's based on the SBWR design.

6 As GEH has already presented, they use 7

typical BWR bottom entry control rods. The design 8

does include defense-in-depth and diverse features for 9

shutting down the reactor and controlling reactivity.

10 And this topical report that we are 11 describing provides design requirements, as well as 12 assessments regulatory requirements, related to 13 reactivity control.

14 Next slide, Rani. The topical report 15 specifies design requirements for the control system, 16 RPS as well as alternate rod insertion system.

17 There's a couple others there. We will be 18 going into much more detail on these systems in the 19 closed session.

20 Go to the next slide, Rani. Here's the 21 list of the regulations we evaluated as part of the 22 topical report.

23 The focus is on 50.62. The ATWS rule.

24 However, the topical report and our safety evaluation 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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54 does address a long list of GDCs.

1 The GDCs that are underlined in this slide 2

will be presented in the closed session in much more 3

detail. The GDCs which are not underlined, we do not 4

have any specific slides on so now would be probably 5

the right time to ask any questions on these 6

particular GDCs.

7 But in the interest of time, GEH's 8

approach that they described for meeting these GDCs, 9

which are not underlined, seemed fairly typical and 10 traditional. And our overall conclusion, specific to 11 these GDCs, is that the approach is consistent with 12 how they have it implemented historically. So there 13 are no specific slides on the GDCs which are not 14 underlined.

15 And if there is no questions, I'll think 16 we'll just wrap up the conclusion on the next slide, 17 Rani.

18 We did write a few limitations and 19 conditions in our safety evaluation for this topical 20 report. These were mainly in areas where the topical 21 report, it didn't really specify what form of analysis 22 will be performed in the future to demonstrate 23 compliance with the regulation.

24 And so, we wrote a few limitations and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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55 conditions sort of establishing the analysis the Staff 1

expects that would be included in a future licensing 2

submittal.

So it's really more of just a

3 clarification of our expectations.

4 In conclusion, we did find that the 5

topical report provided an acceptable description of 6

design requirements, the acceptance criteria and the 7

regulatory basis for the BWRX-300 reactivity control 8

functions and features.

9 And as a disclaimer, the detailed design 10 of the BWRX-300 SMR is not complete. And the Staff 11 does expect that an applicant demonstrate compliance 12 with the regulations. And if they cannot demonstrate 13 compliance, we do expect an adequate justification for 14 an exemption.

15 And with that, the Staff will evaluate any 16 regulatory compliance, with the final design, when we 17 receive an application in the future. And that's all 18 I had for the open presentation.

19 CHAIRMAN MARCH-LEUBA: Ryan, this is Jose 20 again. GE went into some detail under the GDC 27 21 issue, but can you say in open session whether there 22 is an issue with return to power when the control was, 23 not in ATWS, but when control rods go in and two rods 24 remain stuck.

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

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56 MR. NOLAN: Yes. My understanding of the 1

design is that it is capable of maintaining the 2

reactor shutdown, assuming a single failure of the 3

worst rod pair. So they, my understanding is, with 4

two rods out the reactor will remain shut down.

5 CHAIRMAN MARCH-LEUBA: Of co-conditions 6

and --

7 MR. NOLAN: Yes.

8 CHAIRMAN MARCH-LEUBA: -- CW3?

9 MR. NOLAN: That is --

10 CHAIRMAN MARCH-LEUBA: Okay. So there is 11 no issue with return to power?

12 MR. NOLAN: No. Oh, and then with respect 13 to your question on 50.62(c)(5), which is the 14 requirement for an automatic recirc pump trip, and the 15 question was whether an exemption is needed or not, 16 our position is that it is not applicable and an 17 exemption is not needed.

18 It's a natural circulation plant, they 19 don't have recirc pumps. And so that particular 20 regulation is not applicable, no exemption is needed.

21 However, we do expect, we will review any 22 compensating measures that are taken to address that.

23 Maybe the intent behind that role. And this is 24 consistent with what was done for the ESBWR.

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

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57 CHAIRMAN MARCH-LEUBA: So that's good.

1 That's a good answer. I wouldn't even call it 2

transformational.

3 Yes, we don't need to do work when no work 4

is needed. If we can say, duh, it's obvious, we can 5

save a month of work.

6 MR. NOLAN: Yes, that's correct.

7 CHAIRMAN MARCH-LEUBA: Thank you. So, are 8

you done

with, the Staff is done with the 9

presentation?

10 MR. NOLAN: Yes. That concludes my 11 presentation.

12 CHAIRMAN MARCH-LEUBA: So this concludes 13 the complete open session presentation. Can we open 14 the phone line please?

15 At this point, anybody in the public, on 16 the phone line, that wants to make a comment, please 17 state your name and make your comment. Is the phone 18 line open? Public phone line?

19 MEMBER BROWN: Hello?

20 CHAIRMAN MARCH-LEUBA: Yes.

21 MEMBER BROWN: Jose? Jose?

22 CHAIRMAN MARCH-LEUBA: Yes.

23 MEMBER BROWN: This is Charlie. I've lost 24 all power in my house. None of my phones are working, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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58 other than my cell phone, which has no coverage.

1 Almost. I'm probably going to trip off. Hind winds 2

and something is going down, so I won't be back in 3

until I can get some power.

4 CHAIRMAN MARCH-LEUBA: All right, it's 5

okay. Thank you for letting us know.

6 MEMBER BROWN: Okay. Yes, thank you.

7 Take care.

8 CHAIRMAN MARCH-LEUBA: Any other comments?

9 All right, we'll assume the public doesn't have any 10 more comments.

11 Any Members of the Committee want to make 12 a comment on the record, at this moment?

13 MEMBER KIRCHNER: Jose, this is Walt 14 Kirchner. Just an observation, maybe for David from 15 GE to answer.

16 He explicitly, I know that this topical 17 report is about the activity control and design 18 requirements, but under Defense Line 3 he has the 19 reactor protection system scram and the isolation 20 condensing system. I would assume then the RPV is 21 also in that category, is that correct?

22 That's more of a

question or a

23 clarification for GEH.

24 CHAIRMAN MARCH-LEUBA: But I do think that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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59 we need to ask that question in closed session.

1 Because we'll get into details of their proprietary 2

design. If you don't mind --

3 MEMBER KIRCHNER: Oh, sure. No, that's 4

fine. It's just more an observation.

5 CHAIRMAN MARCH-LEUBA: Yes. Yes, thank 6

you. Any other comments or questions? Hearing none, 7

we are going off the record.

8 (Whereupon, the above-entitled matter went 9

off the record at 10:46 a.m.)

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.

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ACRSSubcommitteePresentation GEHitachi(GEH)

LicensingTopicalReport(LTR)NEDC33912P BWRX300ReactivityControl (OpenSession)

November2,2020

Agenda(OpenSession)

LicensingTopicalReportPurposeandScope DefenseinDepthDesignFeaturesforBWRX300ReactivityControl SummaryofDesignFeaturestoMeetRegulatoryRequirementsandProvide DefenseinDepthforReactivityEvents RegulatoryEvaluation

Licensing Topical Report Purpose and Scope

LicensingTopicalReportPurposeandScope Providethedesignrequirements,acceptancecriteria,andregulatorybasisfor theBWRX300RPSandotherassociatedmeansofreactivitycontrol:

BWRX300meansofreactivitycontroldesignfunctions

- SpecifydesignrequirementsfortheRPStoensureregulatoryrequirementsaremet

- Specifydesignrequirementsforothermeansofreactorshutdowntoensurethatdefenseindepth diversityrequirementsaremet

- SpecifydesignrequirementsforotherfunctionssuchasAlternateRodInsertiontoensurethehydraulic scrammeetsreliabilityrequirements

- SpecifyBWRX300acceptancecriteriaandassociatedmitigatingstrategyinresponsetoanATWSas evaluatedagainst10CFR50.62

- Describecompliancewiththerequirementsof10 CFR 50Appendix A,GeneralDesignCriteria(GDC) 12, GDC 20,GDC 21,GDC 22,GDC 23,GDC 24,GDC 25,GDC 26,GDC 28,andGDC 29

- DescriberegulatoryapproachforGDC27

LicensingTopicalReportPurposeandScope Providethedesignrequirements,acceptancecriteria,andregulatorybasisfor theBWRX300mitigatingsystemsassociatedwithanATWS:

BWRX300mitigatingsystemsassociatedwithanATWS

- SpecifydesignrequirementsforsystemstocontrolreactorpressureduringanATWS

- Specifydesignrequirementsforadditionalmeansofreactorshutdowninthecaseoffailureofallmeans ofhydraulicinsertionofcontrolrods

- SpecifyBWRX300acceptancecriteriaandassociatedmitigatingstrategyinresponsetoanATWSas evaluatedagainst10CFR50.62

DefenseinDepthDesignFeatures forBWRX300ReactivityControl

DefenseinDepthDesignforBWRX300 BWRX300appliesadefenseindepthapproachalignedwiththeIAEA guidance

Addressfundamentalsafetyfunctionstoensureoverallplantsafety

AssignsBWRX300functionstodefenselinesassociatedwithfundamentalsafety functions

ThisLTRisfocusedonthefundamentalsafetyfunctionofreactivitycontrol

- Ensureadequatedefenseindepthofshutdowncapabilityandreactivitycontrol

DefenseinDepth-DefenseLine1 DefenseLine1(DL1)

IAEA Level1 DefenseLine1:

ReducechallengestotheReactorProtectionSystemfromall occurrences

- Fewertripsperyear

- ReducesnumberofAOOs

SometransientsbecomeInfrequentEventsdefinedas< 1per 100Reactoryears

StrengthensubsequentlinesofDefense

- Quality

- Reliability

- Conservatism

DefenseinDepth-DefenseLine1 DefenseLine1(DL1)

IAEA Level1 DefenseLine1Examples:

TechnicalSpecificationoperationalcontrols

NLatticecorelesslikelytoexperiencecontrolrodbinding

Advancesinchannelmaterialsandcoredesign/operation minimizeprobabilityofchannelbow

Normalpowerchangesarewithcontrolrods-continuous observationofnormalfunction

Reliabilitymeasuresincludedindesignminimizeprobabilityof PostulatedInitiatingEvents(PIEs)andfailureofmitigation

FineMotionControlRodDrives(FMCRD)withimproved reliability

IAEA Level1 DefenseLine1Examples:

Seismicqualificationensurescoregeometrymaintained

FMCRDssimilarto ABWRandESBWR

ControlRodBlades

- SameasABWR

- AlmostidenticaltolatestdesignforBWRfleet

ABWRfleethas22+yearsofoperatingexperiencewithcontrol rodbladesandFMCRDs

IAEA Level2 DefenseLine2:

Includesfunctionswhichnormallycontroltheplant

PlantfunctionsdesignedtocontrolorstopaPIE

MinimizesPIEsthatreachDL3setpoints

IndependentfromDL3

IAEA Level2 DefenseLine2Mitigation:

Diversemeanstoshutdown

Otherdiversesystemactuations

Controlofpowergenerationsystemscanassistwithmitigation offailureswithinshutdownsystems

RodBlockmitigatesincorrectrodwithdrawal

IAEA Level3 DefenseLine3:

IncludesfunctionswhichacttomitigateaPIE

Ensureplantisplacedinasafestate

Assignedtohighestsafetyclass

IndependentofDL2

IAEA Level3 DefenseLine3Mitigation:

ReactorProtectionSystem(RPS)Scram

IsolationCondenserSystem

IncludesfunctionstomitigateaPIEalongwithfailureofDL3

MitigatesCCFsinDL3

Ensureplantisplacedinasafestate DefenseLine4a(DL4a)

IAEA Level4

AlternateRodInsertion(ARI)- provideshydraulicscraminevent ofHydraulicControlUnit(HCU)actuationfailure

FMCRDinsertionwithmotors DefenseLine4a(DL4a)

IAEA Level4

Functionstopreventormitigatesevereaccident

ProtectsfromeventsthatexceedDL1assumptionssuchas extremeevents,multipleevents,ormultiplefailures DefenseLine4b(DL4b)

IAEA Level4

TheneedforfeaturesinDL4bwillcontinuetobeevaluated throughtheProbabilisticRiskAnalysis(PRA)eventsequences analyses DefenseLine4b(DL4b)

IAEA Level4

DesignFeaturestoMeetRegulatory RequirementsandProvideDefenseinDepthfor ReactivityEvents

ControlRoddesignproven inBWRoperatingfleet

NLatticecoreprovidesample spaceforcontrolrodtravel

GNF2fuelcurrentlyoperatingin BWRfleet

FMCRDsareevolutionfromBWRfleethydrauliccontrolroddrives

Motorprovidesnormalmeansofcontrolrodmovement

Hydraulicscramdiversefrommotordrivenmovement

FMCRDsproveninoperatingABWRs

DrivenbyfailsafeHydraulicControlUnits(HCUs)

ARIvalvesprovidediversemeanstoreleasestoredenergy

Scramoutletvalveandscramdischargevolumeeliminated-nohydrauliclock potential

LargeRPVsteamvolumeresultsinlower pressurizationrateforisolationevents(compared toABWRandexistingBWRs)henceresultingin lessreactivityeffect

RefertoNEDC33910P,BWRX300Reactor PressureVesselIsolationandOverpressure Protection

HeatexchangerdesignandcapacityofeachICS trainisthesameasESBWR

Failsafe,simplesystem

Limitsreactorpressureandtemperatureand maintainsreactorwaterinventory

Condensatereturnvalves(notshown)failopenon lossofpowertothevalves

CompliancetoRegulatoryRequirements

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 26 Applicabilityof10CFR50.62toEvolutionaryPlants DuringtheATWSrulemakingtheNRCstaffsetagoalthatfrequencyofan ATWSshouldbenomorethan1.0E05/reactoryear NUREG1780 UsingoperatingdatasincetheATWSrulewasimplemented,foundthaton agenericbasis,allfourreactortypesachievedtheATWSruleriskgoal.

NUREG0800,SRP15.8,statesthefollowing:

A.ForevolutionaryplantswheretheATWSruledoesnotexplicitlyrequireadiverse scramsystem,theapplicantmayprovideeitherofthefollowing:

i.Adiversescramsystemsatisfyingthedesignandqualityassurancecriteriaspecified inSRPSection7.2 ii.DemonstratethattheconsequencesofanATWSeventarewithinacceptable values BWRX300meetsbothrequirements

Alternatemeansforshutdown

ARIandelectricmotorruninincludedinDL4a

SuccessfulscramensuredbyDL2,DL3,DL4a

Consequencesoffailuretoscramfromallthreelayersofdefenseacceptablebyuseof DL4a

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 28 DesignFeaturesRequiredbyATWSRule 10CFR50.62mandatesreductionofriskfromanATWS 10CFR50.62(c)(3),(4)and(5)requirethefollowingdesignfeaturesforBWRs:

AlternateRodInsertion(ARI)System

AutomaticSLCS

AutomaticRecirculationPumpTrip

RPSactuatedHCUstoreleasestoredhighpressurewaterfromaccumulators

DiverseARIpilotvalvesoncontrolairheaderforscramvalvestoreleasestoredenergy forscram AdditionallyFMCRDshaveelectricmotordrivenpositioningusedforboth insertionandwithdrawalofthecontrolrods Electricmotordiversefromthehydraulicscramfeature

Allowsrodmovement,evenwithfailureofARIsystem

UtilizesensorsandlogicthatarediverseandindependentoftheRPS Eliminatedcommonmodefailureofhydraulicscrambyeliminatingthescram dischargevolume

UsestheDefenseinDepthapproachdelineatedinIAEASSR2/1toprovide multiplelayersofdefensetoensurereactorisshutdown

BWRX300utilizesnaturalcirculationandhasnorecirculationpumps BWRX300designalsoutilizes:

Controlofpowergenerationsystemstoassistinmitigation

Reduceswaterlevel,coreflowandreactorpowersimilarto RPTinaforced circulationplant

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 32 RegulatoryAcceptanceCriteria PrimarySystem Maximumprimarystresswithin(RCPB)doesnotexceedthe emergencylimitsasdefinedintheASMEB&PVCode,SectionIII FuelIntegrity Claddingtemperatureandoxidationcriteriaof10CFR50.46 met ContainmentIntegrity Maximumcontainmentpressuredoesnotexceedthe designpressure RadiologicalReleases Maintainedwithin10CFR100allowablelimit ShutdownandCooling Reactorisbroughttolongtermshutdownwith continuedeffectivecorecooling

Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 33 10CFRPart50,AppendixA,GDC27 10CFRPart50,AppendixA,GDC27,CombinedReactivityControlSystems Capability Thereactivitycontrolsystemsshallbedesignedtohavea combinedcapability,inconjunctionwithpoisonadditionbytheemergency corecoolingsystem,ofreliablycontrollingreactivitychangestoassurethat underpostulatedaccidentconditionsandwithappropriatemarginforstuck rods,thecapabilitytocoolthecoreismaintained

Exception Corecoolability ismaintainedforlossofcoolantaccidents becauselossofwaterinventoryintheRPVisminimizedbytheassured functionofRPVisolationvalvestomitigatelargelinebreaks

RefertoNEDC33910P,BWRX300ReactorPressureVesselIsolationand OverpressureProtection

NRC Staff Presentation-Open Session GEH Topical Report NEDC-33912P, Revision 0, Supplement 1, BWRX-300 Reactivity Control BWRX-300 Small Modular Reactor ACRS Subcommittee Meeting November 2, 2020

NRC Staff Review Team

BWRX-300 Background

NRC Staff Review of NEDC-33912P

Conclusion 2

Presentation Outline

NRR Nuclear Methods, Systems, and New Reactors Branch (SNRB)

Ryan Nolan

Andrew Proffitt

Alex Siwy NRR PRA Licensing Branch C (APLC)

Anne-Marie Grady

Alissa Neuhausen NRR Instrumentation and Controls Branch A (EICA)

Dinesh Taneja NRR New Reactor Licensing Branch (NRLB)

Rani Franovich 3

NRC Staff Review Team

300 megawatt electric small modular reactor

Uses natural circulation and passive cooling isolation condenser system

Based on ESBWR design

Uses typical boiling-water reactor bottom-entry, cruciform-shaped control rods

Includes defense-in-depth and diverse features to ensure the capability to shut down and control the reactor

NEDC-33912P specifies design requirements and assesses regulatory requirements related to reactivity control 4

BWRX-300 Background

NEDC-33912P specifies design requirements for:

Rod control system

Reactor protection system

((

))

Alternate rod insertion

((

))

5 BWRX-300 Reactivity Control Systems and Functions

Evaluation of Applicable Regulations 10 CFR 50.62, Requirements for reduction of risk from ATWS events 10 CFR 50, Appendix A, General Design Criteria

GDC 12, Suppression of reactor power oscillations

GDC 20, Protection system functions

GDC 21, Protection system reliability and testability

GDC 22, Protection system independence

GDC 23, Protection system failure modes

GDC 24, Separation of protection and control systems

GDC 25, Protection system requirements for reactivity control malfunctions

GDC 26, Reactivity control system redundancy and capability

GDC 27, Combined reactivity control systems capability

GDC 28, Reactivity limits

GDC 29, Protection against anticipated operational occurrences Proprietary Information 6

Conclusion

With specified Limitations and Conditions, NEDC-33912P provides an acceptable description of design requirements, acceptance criteria, and regulatory bases for design features of the BWRX-300 reactivity control functions.

Detailed design of BWRX-300 SMR is not complete.

If applicant is not able to demonstrate compliance with NRC regulations, the applicant will be expected to justify an exemption from the applicable requirement.

NRC staff will evaluate regulatory compliance of the final BWRX-300 design with regards to reactivity control during future licensing activities for BWRX-300 applications.

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8 Proprietary Information

ML20344A443

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