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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
From:	Zena Abdullahi; Advisory Committee on Reactor Safeguards
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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.

Court Reporters and Transcribers 1323 Rhode Island Avenue, N.W.

Washington, D.C. 20005 (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.

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1 1 UNITED STATES OF AMERICA 2 NUCLEAR REGULATORY COMMISSION 3 + + + + +

4 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 5 (ACRS) 6 + + + + +

7 ACCIDENT ANALYSIS AND THERMAL-HYDRAULIC SUBCOMMITTEE 8 + + + + +

9 MONDAY 10 NOVEMBER 2, 2020 11 + + + + +

12 The Subcommittee met via Teleconference, 13 at 9:30 a.m. EST, Jose March-Leuba, Chairman, 14 presiding.

15 COMMITTEE MEMBERS:

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

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2 1 ACRS CONSULTANTS:

2 MICHAEL L. CORRADINI 3 STEPHEN SCHULTZ 4

5 DESIGNATED FEDERAL OFFICIAL:

6 ZENA ABDULLAHI 7

8 9

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3 1 CONTENTS 2 ACRS Chairman Introductory Remarks 3 Jose March-Leuba . . . . . . . . . . . . . 4 4 GEH Overview of NEDC-33912P 5 George Wadkins . . . . . . . . . . . . . . 5 6 David Hinds . . . . . . . . . . . . . . . . 12 7 NRC Staff Overview of Safety Review 8 Ryan Nolan . . . . . . . . . . . . . . . . 52 9

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4 1 P-R-O-C-E-E-D-I-N-G-S 2 9:30 a.m.

3 CHAIRMAN MARCH-LEUBA: The meeting will 4 now come to order. This is a meeting of the ACRS 5 Accident Analysis and Thermal-Hydraulics Committee.

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

7 Because of COVID-19 concerns, this meeting is being 8 conducted remotely.

9 I see the following ACRS in attendance.

10 Ron Ballinger, Dennis Bley, Charles Brown, Vesna 11 Dimitrijevic, David Petti, Joy Rempe, Pete 12 Riccardella, Matt Sunseri. I also know that our 13 consultants, Mike Corradini and Steve Schultz are also 14 present.

15 Today's topic is Topical Report NEDC-16 33912P, BWRX-300 Reactivity Control. This topical 17 report defines the criteria that we'll be using a 18 future submittal to ensure that BWRX-300 reactivity 19 controls satisfy all applicable regulations.

20 Portions of our meeting will be closed to 21 the public to protect proprietary information. We 22 will have an opportunity for public comments before we 23 start the closed session of the meeting.

24 The ACRS was established by a statute and 25 governed by the Federal Advisory Committee Act, FACA.

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5 1 As such, the Committee can only speak through its 2 published reports.

3 The ACRS section of the U.S. NRC public 4 website provides our chapter, bylaws, agendas, letter, 5 reports and full transcripts for the opened portions 6 of all full and subcommittee meetings. Including the 7 slides presented there.

8 The Designated Federal Official today is 9 Zena Abdullahi. A transcript of the meeting is being 10 kept, therefore speak into the microphones clearly and 11 state your name for the benefit of the court reporter.

12 Please keep the microphone on mute when 13 not being used. And don't use video feed to minimize 14 bandwidth problems.

15 We are expected to have a full committee 16 meeting on this topic in December. At this point, I 17 would like to give the floor to GEH and start your 18 presentation. George, you're on.

19 MR. WADKINS: Good morning. My name is 20 George Wadkins and I am the Vice-president, New Power 21 Plants and Products Licensing for GE Hitachi.

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

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6 1 control.

2 We will be describing design requirements, 3 acceptance criteria and regulatory basis for the BWRX-4 300 reactor protection system, or RPS, and other 5 associated means of reactivity control.

6 As noted in our previous discussions with 7 the ACRS Members, the BWRX-300 builds upon our 8 extensive experience in boiling water reactor 9 technology. Including our most recent experiences in 10 development and certification of the economically 11 simple boiling water reactor or ESBWR.

12 The BWRX-300 design leverages the use of 13 proven technology to the greatest extent possible 14 while incorporating advances and design requirements 15 and features to further enhance nuclear safety and to 16 provide for the protection of the public in the 17 unlikely event of an accident.

18 I first want to thank the NRC Staff for 19 their in-depth professional review of this licensing 20 topical report. The interactions with the NRC Staff 21 were extremely useful in ensuring that the content of 22 the licensing topical report was complete, 23 understandable, accurate and met the applicable 24 regulatory requirements and guidance.

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

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7 1 interactions with the NRC Staff during this ACRS 2 Subcommittee review and the future ACRS Full Committee 3 review plan for December of this year.

4 As previously requested by the ACRS, we 5 are providing for an extensive open session discussion 6 of the content of this licensing topical report, but 7 also have a planned presentation for a closed session 8 later in this meeting.

9 During our presentation we will pause at 10 the end of each slide to allow for questions from the 11 ACRS Member, but please feel free to raise questions 12 at any time. If the discussions involve proprietary 13 information, then we will request saving the question 14 until the latter closed session.

15 CHAIRMAN MARCH-LEUBA: So, let me take 16 advantage of the break and thank you for making such 17 an extensive open session presentation. Obviously, it 18 was very good.

19 And also, know that Member Walter Kirchner 20 has also joined us. Go ahead.

21 MEMBER REMPE: Jose, this is Joy.

22 CHAIRMAN MARCH-LEUBA: Yes, Joy.

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

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8 1 of the LTR we were given is going to change a lot 2 based on the response to an RAI.

3 When will we see, will we see that updated 4 version of the LTR before the December meeting?

5 CHAIRMAN MARCH-LEUBA: I'm going to let 6 the Staff probably handle that, but the process is, 7 notifications that are proved on the RAI, are 8 committed to an RAI, is getting incorporated in the 9 dash A approved version.

10 So, the Staff, can somebody from the Staff 11 handle this question?

12 MS. FRANOVICH: This is Rani Franovich, 13 the project manager for GEH. I just want to make sure 14 I understand the question.

15 Is the question, will the ACRS Members 16 have an opportunity to review the RAIs and the RAI 17 responses?

18 MEMBER REMPE: No, we did see that. And 19 in this case, yes, if it's a small change, yes, we 20 don't usually see it unless, like Jose said, it's just 21 assumed it's going to happen.

22 But it's a substantial difference and I 23 just was wondering, is that going to be the Staff's 24 approach this time, will GE provide an updated version 25 that incorporates this change?

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9 1 It's in Section 4.1. And I don't want to 2 get into a lot of the details of the change, but it's 3 basically a description of this second independent 4 reactivity control system.

5 And to me that's a, it's quite a bit of a 6 difference and I just am wondering, are we going to 7 see this update at all or is the plan just wait and 8 they're going to send an updated version based on this 9 response and that's it.

10 MS. FRANOVICH: Okay. Thank you for that 11 clarification.

12 If I could suggest that we cover that when 13 the Staff has its turn to present to the ACRS, we'll 14 address it at that time.

15 MEMBER REMPE: Okay, that sounds fine.

16 Thank you.

17 MS. FRANOVICH: Thank you. George, back 18 to you.

19 MR. WADKINS: Okay, thank you, Rani. So, 20 proceeding on to Slide 2.

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

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10 1 related defense-in-depth design features applicable to 2 the reactivity control fundamental safety function.

3 We will also discuss a summary of the 4 design features related to the BWRX-300 reactivity 5 control fundamental safety functions for events 6 requiring use of reactivity control measures for 7 ensuring safety. And we will discuss the regulatory 8 evaluations in demonstrating compliance with the NRC 9 regulatory requirements and conform to NRC regulatory 10 guidance.

11 So, proceeding to Slide 4. Slide 4 and 5 12 will describe the purpose and scope of the licensing 13 topical report, which includes the design 14 requirements, acceptance criteria and regulatory basis 15 for the BWRX-300 reactivity control design functions.

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

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11 1 requirements.

2 We will discuss the BWRX-300 acceptance 3 criteria and associated mitigating strategy in 4 response to an anticipated transient without scram, or 5 ATWS, as evaluated against the requirements of 10 CFR 6 50.62. And we will describe compliance with the 7 requirements of 10 CFR 50 Appendix in the GDCs 12, 20, 8 21, 22, 23, 24, 25, 26, 28 and 29.

9 We will also describe our regulatory 10 approach for General Design Criteria 27 where we have 11 specified a principle design criteria due to the 12 language of that GDC and how our design approaches 13 these additional means of reactor shutdown.

14 And additionally, as we look at Slide 5, 15 we will discuss the BWRX-300 mitigating systems 16 associated with an ATWS event, anticipated transient 17 without scram. We will specify design requirements 18 for systems to control reactor pressure during an ATWS 19 event.

20 We will specify design requirements for 21 additional means of reactor shutdown. In the case of 22 failure of all means of hydraulic insertion of the 23 control rods.

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12 1 in response to an ATWS as evaluated against the 2 requirements of 10 CFR 50.62. Are there any questions 3 on the LTR purpose and scope?

4 CHAIRMAN MARCH-LEUBA: No.

5 MR. WADKINS: Okay. I will now turn over 6 the presentation to David Hinds, principle design 7 engineer for the BWRX-300. He will continue 8 describing the non-proprietary contents and 9 conclusions of the licensing topical report.

10 Assisting David, when necessary to answer 11 questions, maybe Lou Lanese, the GEH senior licensing 12 engineer for this licensing topical report, and 13 Charlie Heck, GEH senior consulting engineering, 14 responsible for safety and transient analysis. So, 15 I'll turn it over to David.

16 MR. HINDS: Okay, thank you. Good 17 morning. So this is David Hinds.

18 As was stated a minute ago, I'll just 19 reinforce that we have two slide materials. One for 20 the open session, one for closed session. So, 21 dependent upon the way the questions and discussion 22 go, we may need to defer some topics over to the 23 second session.

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

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13 1 as maybe required. And so, if there is detailed 2 questions we'll likely ask to defer them.

3 Okay. So, the first area, just to give a 4 feel for their GEH design approach we've taken for 5 BWRX-300, not only in this area but across the board, 6 but the slides are focused upon the results obtained 7 in this area.

8 In the area of our defense-in-depth type 9 of design approach. And it's especially pertinent to 10 this topical area to ensure that the means for reactor 11 control and reactivity shut, or reactor shutdown, are 12 maintained and in a defensive type posture of defense-13 in-depth.

14 So, the next slides we'll be walking 15 through will show some of the ways we've laid that 16 out. And we use terminology that comes from the 17 principles developed through the IAEA. So these next 18 few slides use some of that language.

19 We applied defense-in-depth approach. It 20 is aligned with the IAEA principles. We have done 21 some customizing within GEH to develop our process 22 specific to align to that type of approach.

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

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14 1 are maintained with more than one layer. In fact, at 2 least two layers for each postulated initiating event.

3 In some cases we've even had more than two layers in 4 place.

5 So, we evaluate each one of the postulated 6 initiating events. We used the fundamental safety 7 functions. And we assign functions within the design 8 that mitigate in multiple layers.

9 And we ensure those functions when the 10 design is implemented or have the appropriate 11 independence within the design process. So, again, 12 this LTR is focused on that fundamental safety 13 function of reactivity control.

14 Go to the next slide please. Okay. All 15 right, so, the first defense line, within the IAEA 16 terminology is, we've got Defense Line 1, which it 17 really amounts to design approaches and fundamentals 18 within the design to reduce challenges to the reactor 19 protection system, reduce challenges to overall 20 reactivity control.

21 Some of them result in fewer trips per 22 year, so we add reliability features to the plant to 23 minimize the number of trips and the number of 24 challenges to the plant. So, fundamentals begin from 25 those basic approaches.

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15 1 We strengthen the, all the defense lines 2 through high-quality, reliability conservatisms. So, 3 the Defense Line 1 is a way that we do our design and 4 the fundamentals that apply across the board as 5 opposed to actual physical systems.

6 If you could go to the next slide. Okay, 7 so some of the examples of some of these fundamentals 8 that result in added safety to the plant are, and of 9 course they're common to other reactor designs as well 10 and our past designs.

11 Of course, technical specifications 12 control the operational controls. We've made many 13 design choices, and I list some of them here.

14 And we have N-Lattice core makes the gap 15 between the control rod, the fuel bundles, where the 16 control rods ride to have less probability of rod 17 binding taken into account. Considerations such as 18 channel bow and potential for degradation or movement 19 in the shape of the fuel channels over the life of the 20 core.

21 And we ensure that we have margins to 22 ensure that we did not create a binding situation.

23 Those are types of approaches that apply to reactivity 24 control.

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16 1 in this plant. This is a natural circulating power 2 plant so therefore we do not use recirculating pumps 3 to change core flow, and therefore change reactor 4 power. Like some of the, rest of the BWR fleet.

5 So therefore we are constantly, on a daily 6 basis, ensuring the control rods are moving 7 appropriately and controlling the reactor appropriate 8 so therefore no surprises in that, a hidden 9 malfunction in the control ride drive system. And 10 that that's the normal means for power change.

11 We incorporate many reliability features 12 within all of the systems design, with a heavy focus 13 on these associated reactor safety.

14 I alluded to, and I think you are already 15 aware, that this design uses the fine motion control 16 rod drives, which we have experience with through the 17 ABWR fleet development. And we continue to develop 18 through our ESBWR development. And now are carrying 19 forward to BWRX-300.

20 We'll continue to speak more about the 21 design features here in some of the subsequent slides.

22 But the fine motion control rod drives do, that design 23 choice does aid in the reliability of the reactor 24 control fundamental safety function.

25 Okay. Next slide.

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17 1 CHAIRMAN MARCH-LEUBA: I assume you have 2 some experience with, because this control rod motion, 3 continuous control rod motion to compensate for burn-4 up, what, control areas where there are recirculation 5 pumps, let's see, what do, plays more strain on the 6 fuel, I'm thinking PCI interactions, better planning?

7 MR. HINDS: So, a couple of comments on 8 that. This core, and again, in this Defense Line 1 9 area it's design decisions, and you've alluded to 10 another.

11 So, we made design decisions to 12 intentionally re-limit the power density of this 13 plant. So, we've made design choices on core design 14 to not push it to achieve all the power that we could 15 potentially achieve out of the core of this size.

16 So, limiting the power density, making 17 design decisions on the actual fuel load. And the 18 number of fuel bundles, we did optioneering, we called 19 it, of how many fuel bundles would this core contain.

20 Our final selection was, much of it was 21 based upon ensuring that we limit fuel duty. So, we 22 have looked heavily at fuel duty and mechanisms such 23 as PCI.

24 So, do not think it's going to be a 25 problem, in brief summary. Some other --

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18 1 CHAIRMAN MARCH-LEUBA: And you're not --

2 MR. HINDS: Yes.

3 CHAIRMAN MARCH-LEUBA: You're not already 4 planning for a power uprate, are you?

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

6 CHAIRMAN MARCH-LEUBA: Not yet.

7 MR. HINDS: Our intention is, that we 8 selected the appropriate power level for this plant.

9 And that was part of our optioneering.

10 But we did it, again, in a very 11 conservative fashion knowing that control rods are the 12 normal means of maneuvering the plant. And so, we did 13 limit our priorities.

14 But no, we did not plan for a power 15 uprate.

16 CHAIRMAN MARCH-LEUBA: Okay, thank you.

17 MR. HINDS: Okay. So, other design 18 choices we've made that help with the conservatism and 19 safety of the plant, of course, seismic qualification.

20 This is all design with a high seismic margin.

21 I mentioned the FMCRDs. We did have the 22 operating experience with ABWR, continued to design 23 the experience with ESBWR.

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19 1 understand all the details of their behavior and the 2 way to manufacturer.

3 And so we've been through generations of 4 control rod blades. And we carry that forward to the 5 BWRX-300.

6 And I think we've mentioned it in one of 7 our prior meetings, but we are using the same fuel and 8 control rod blades that we've been advancing through 9 our operating fleet. So the length of the fuel bundle 10 is our standard GNF2 fuel and therefore the standard 11 control rod blade. So therefore it's not a first of 12 a kind development that we bring with it some sort of 13 questions.

14 And just list that many years of 15 experience with, up to and including, the ABWR, 16 although some might think it's a new plant, it's got 17 years of experience. And there is multiple plants 18 that have operated in Japan. Okay.

19 DR. SCHULTZ: David, this is Steve 20 Schultz.

21 MR. HINDS: Yes.

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

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20 1 you've gained from the other unit designs.

2 Anything in particular that has improved 3 the reliability of that system, over and above, what 4 you've seen before in your operational experience?

5 MR. HINDS: We have some plans where, 6 depending upon the level of detail I might need to 7 revert to the second segment of this. But we have 8 made some changes to our motor selection.

9 We have gone through a series of coupling 10 designs and coupling selections. And related to the 11 motor selection it also determines the capability of 12 how fine of a movement.

13 If it's okay with you, I'll come back to 14 this and maybe highlight a few other features when I'm 15 showing some visuals in the second segment. And 16 please, if I didn't adequately address your question 17 at that time please readdress it. But I wrote a note 18 for myself, I'll bring up again.

19 But again, primarily in the motor 20 coupling, we've also gone through into the bearings 21 and looked for material reliability. But I'm not 22 stating that we have a reliability problem with the 23 current fleet of FMCRDs, we just continually look to 24 advance and learn.

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21 1 very much. I look forward to your further remarks.

2 MR. HINDS: Okay, thank you.

3 CHAIRMAN MARCH-LEUBA: I have lost the 4 slides. Oh, there they are.

5 MR. HINDS: Yes, they dropped off for a 6 second, sorry. Okay, continuing through our defense 7 line type of defensive measures.

8 Now, once we get beyond Defense Line 1 and 9 we get into mitigating systems and features, more into 10 what we typically look into systems.

11 So, in Defense Line 2 includes functions 12 which would normally control the plant. We do have 13 added levels of quality for those systems, although 14 they're not using the U.S. terminology, safety 15 related, but using international terminology, they are 16 Safety Class 3.

17 So we do apply a higher degree of controls 18 upon design and procurement. And so we do get some 19 credit for safety, but it's only one layer. Defensive 20 layer.

21 They play a large role in limiting and/or 22 preventing a postulating and initiating event. And 23 they minimize postulated initiating events, I'm sorry 24 if I did this on the acronym PIE, that reach Defense 25 Line 3 set points.

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22 1 Defense Line 3 is that layer right in the 2 heart of safety, which is what, in U.S. terms, would 3 be safety related or in international terms, safety 4 class 1. So Defense Line 2 is a front-line defensive 5 layer to prevent challenges to the core of the safety 6 of the plant.

7 But we have a high focus and an elevated 8 focus on that layer in this plant, which is one of the 9 things that we've done to add a more defense-in-depth 10 type approach to this plant.

11 If we can go to the next. And so I'll 12 show you --

13 CHAIRMAN MARCH-LEUBA: So would you say 14 that this is the control system that is non-safety 15 grade that prevents the accident, the initiated events 16 from getting worse, is that correct?

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

18 And they additionally will minimize the number of 19 initiating events because, historically, many of the 20 postulated initiating events originated in what we're 21 now calling our Defense Line 2, or Safety Class 3 22 systems.

23 Things like the feedwater control system.

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

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23 1 also helps to limit other related initiators.

2 CHAIRMAN MARCH-LEUBA: So, what really is 3 the alliance is, because you plan to use digital 4 controls, computer controls, you can do more than an 5 analog controller?

6 MR. HINDS: Right.

7 CHAIRMAN MARCH-LEUBA: Okay. If the 8 feedwater is fast running away, you can create some 9 safety functions inside a controller that would bring 10 it back.

11 MR. HINDS: Yes.

12 CHAIRMAN MARCH-LEUBA: Which you couldn't 13 do with an analog controller.

14 MR. HINDS: Yes. We would --

15 CHAIRMAN MARCH-LEUBA: Good.

16 MR. HINDS: Your statements are correct.

17 We're using digital controls. And our defensive 18 layers are separated digital controls.

19 So the Defense Line 2 is separate from our 20 Defense Line 3 and so therefore if you go down the 21 path, common cause failure, it's not, it will add a 22 defensive layer, as well as the capabilities of 23 technology advance, as you had just mentioned, help as 24 well.

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24 1 like a rod connector. It makes sense.

2 MR. HINDS: Okay. And we have, the really 3 nice thing about our Defense Line 2 and those systems, 4 we, again, picture high quality systems, we call 5 Safety Class 3, and we apply high reliability features 6 such as a selection of a triplicated controller versus 7 just a simple singular controller. And those features 8 add significant reliability to the plant.

9 I'll go more into the details of what's in 10 Defense Line 2. These are kind of high-level terms.

11 And some of those details will be in the next segment, 12 so if you don't mind, I'll do some higher level 13 introduction here and then revisit it again later.

14 MEMBER BLEY: Just to interrupt a second.

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

16 MEMBER BLEY: This is Dennis Bley. I 17 don't really want to dig into it here but I'm guessing 18 that when we get the reviewing I&C we'll dig into this 19 Defense Lines 1, 2 and 3 business. If that's true, 20 that's fine.

21 If it's not, maybe you can give us more 22 detail in what you mean by, they are separate from 23 each other. That can mean lots of different things.

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

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25 1 I'm happy to put this off to I&C, but if it's not 2 going to be there, maybe you can talk more about it.

3 MR. HINDS: Okay. We'll do both. I'll 4 touch it again in our next segment, in the second 5 portion of our presentation in closed session, and 6 then you'll also see it again whenever you see I&C 7 submitted for that portion of licensing. So we'll hit 8 them both.

9 But in simple summary, they're quite 10 separate. But I will get back to it in the second 11 segment of this. I understand your question.

12 MEMBER BLEY: Okay, thanks.

13 MR. HINDS: So, control power generation 14 systems, they, again, limit and mitigate events. I'll 15 touch more on this in the later segment.

16 In Defense Line 2 we also mitigate 17 incorrect rod potential, postulated incorrect rod 18 movements, with rod blocks.

19 George, if you can go to the next slide 20 please. Okay, Defense Line 3 is the heart of safety, 21 as I mentioned. It's what, in U.S. we've used the 22 term safety related, internationally we call Safety 23 Class 1.

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

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26 1 placed in a safe state, such as a reactor scram. We 2 assign the highest safety class and the highest 3 procurement controls and design controls.

4 And a little bit to your question a minute 5 ago, they are independent of Defense Line 2. I'll 6 keep building on that.

7 Okay, George, next. Okay, so, we, within 8 the BWRX-300 it is a passive safety natural 9 circulating power plant. Hopefully our introduction 10 from a prior ACRS meeting will carry forward to now.

11 I didn't include an overall summary of the 12 BWRX-300 but I'd be glad to revisit anything if there 13 is questions.

14 However, in Defense Line 3, functions 15 associated with reactivity control of interests are 16 the reactor protected system and the associated scram 17 features that implement, that are implemented, or 18 actuated by the reactor protection system, the 19 isolation condenser system for heat removal.

20 Those are key, Defense Line 3, Safety 21 Class 1 or safety related systems and functions that 22 we contain within Defense Line 3.

23 George. Okay. Then the backup, or 24 Defense Line 4 --

25 MEMBER BROWN: Excuse me for a minute.

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27 1 This is Charlie Brown.

2 MR. HINDS: Sure.

3 MEMBER BROWN: Looking through your 4 Defense Lines 1, 2 and 3, I'm the I&C person, 5 representative. Along with Dennis, and anybody else 6 that wants to participate in that area.

7 I was trying to get a handle on the 1, 2 8 and 3. It appears to me that Defense Line 3 is where 9 your classic reactor protection system is called on.

10 And it's the last, I view that as the last line of 11 defense.

12 So the Defense Line 1 and 2, I presume are 13 based on what you've been saying, sound like 14 refinements of your operations and control functions 15 that minimize the likelihood of having to have an 16 automatic reactor protection system response. Am I 17 reading what you're talking about correctly?

18 MR. HINDS: I think most, if not all of 19 your statements, are correct. I'd like to amply on 20 them some in our second segment if --

21 MEMBER BROWN: That's fine.

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

23 MEMBER BROWN: Yes, that's fine. Thank 24 you.

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

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28 1 summary, Defense Line 3 is the hardest safety and that 2 is the traditional and fundamental reactor protection.

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

4 In order to minimize challenges to it, 5 we've added features. And then on the back end, in 6 case we reach low probability failures, set of complex 7 sequence with common cause failure, for example, we've 8 got some backup features. So that's where we are now 9 with this, up to Defense Line 4.

10 MEMBER BROWN: Okay.

11 MR. HINDS: So, Defense Line 4 we've 12 segregated into 4A, 4B. And the 4A includes functions 13 to mitigate postulating initiating events that occur, 14 that postulate occur, and a subsequent postulate 15 failure of the safety related systems to mitigate 16 them.

17 So, a very complex, low frequency 18 occurrence. We plan for them as well to mitigate the 19 common cause failures that, CCF acronym, in Defense 20 Line 3 and ensure plant is in a safe state.

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

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29 1 fail to actuate.

2 We also have another means, because of our 3 design selection way back in Defense Line 1 of our 4 design selection of fine motion control at drive, we 5 have motors in addition to the hydraulics. So it 6 allows another means for the control rods to be 7 inserted.

8 Again, I'll keep revisiting these 9 features. So I'm trying to buzz through a little now 10 and then I'll come back and I'll catch all the 11 questions, I hope.

12 MEMBER BALLINGER: This is Ron Ballinger.

13 I'm assuming, I guess the way I read it, this ARI is 14 a substitute for SLIC?

15 MR. HINDS: Well, ARI provides another 16 means to ensure that the reactor is shutdown. So, in 17 a way I guess you would be correct.

18 So, sure, it's another means for reactor, 19 to ensure the reactor is shutdown. We have, and I'll 20 keep building upon this because some of these we 21 protected are the materials so I won't open so 22 detailed right now but I'll keep revisiting and 23 reinforce that. I wrote a note on that one as well.

24 DR. CORRADINI: So, this is Corradini.

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30 1 here.

2 So, if we go to closed session to explain 3 this, I guess I'd like some clarification as to what 4 the ARI is in difference to what has been common in 5 BWRs and the ESBWR, the SLIC.

6 MR. HINDS: Okay. I'll start answering it 7 and then I'll finish answering in the closed session, 8 if that's okay.

9 But you're correct in, I think, your 10 statement that ARI was used on past BWRs. So that 11 statement is correct.

12 But there are some added features on the 13 BWRX-300. And I'll build upon them as we go.

14 MEMBER BALLINGER: So this is Ron 15 Ballinger again. So I'm assuming that we'll get, at 16 some point, to the PRA later on in time, I guess, and 17 that the alternate rod insertion scheme will have a 18 significant effect on the PRA?

19 MR. HINDS: Yes. It is impactful on the 20 PRA, that is correct. All of these layers have an 21 impact on the PRA.

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

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31 1 continue to use the PRA in parallel with design 2 progression.

3 And you're correct that these features do 4 impact the PRA. I mean, there's a whole layer in the 5 layered failure.

6 MEMBER BALLINGER: Yes. In addition to 7 that, I keep hearing the word, increased reliability, 8 inserted more reliable this, more reliable that.

9 I'm assuming that when we get to the PRA 10 you'll have some kind of data which supports, that 11 puts a number on that.

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

13 Now, yes, within the PRA approved methodologies.

14 That's correct.

15 MEMBER BALLINGER: Thank you.

16 MEMBER REMPE: So that was actually the 17 question I had, was related to the data. Do you have 18 the data or is it envisioned you're going to have to 19 obtain additional data when you come in with 20 additional documents related to this plant?

21 By the time you do a DCA or a Part 50 22 application, will have to obtain additional data?

23 MR. HINDS: And I assumed you were talking 24 about failure. Failure rate type data that's used 25 within the PRA, I assume, based upon your question.

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32 1 MEMBER REMPE: Yes, that. And then I 2 thought there was some also thermal hydraulic features 3 with this plant that were a bit different that I was 4 wondering if there was going to be some sort of 5 testing program to demonstrate them. These features.

6 MR. HINDS: Yes. But we have a detailed 7 thermal hydraulic analysis within our TRACG model.

8 And as we get into the second segment, if 9 you want to go deeper into that, Charlie Heck is on 10 the line who's our expert on that. But yes, we have 11 been doing detailed thermal hydraulic analysis using 12 our TRACG computer code.

13 And we additionally are doing PRA analysis 14 for our frequency of N sequences and the frequency of 15 occurrences.

16 MEMBER REMPE: So, in those, the 17 reliability in the thermal hydraulics, I'm hearing you 18 saying you're doing analysis. But did you have to 19 obtain any additional data or do you need to obtain 20 additional data, is what I was curious about?

21 MR. HINDS: So, for the thermal hydraulics 22 we have been benchmarking for years with the operating 23 fleet. And that data is pertinent to the BWRX-300.

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

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33 1 benchmarking. But we did not envision the necessity 2 for further testing. It doesn't mean we won't do 3 testing, but we do not see the necessity for further 4 thermal hydraulic testing.

5 MEMBER REMPE: Okay. Of reliability 6 testing, so you think the data you have is adequate to 7 support these changes in this design? Is that what 8 you're telling me?

9 MR. HINDS: Yes. It doesn't mean we won't 10 do further confirmatory, but that's what I'm telling 11 you.

12 MEMBER REMPE: Okay, thank you.

13 MEMBER BALLINGER: But the alternate rod 14 insertion system is new?

15 MR. HINDS: The alternate rod insertion is 16 used in the existing fleet. Now, it's not a system 17 that's called upon because it's a deep defensive 18 layer, even on the existing fleet.

19 But the alternate rod insertion is used in 20 the current BWR fleet. It's an alternate means of 21 depressurizing the scram air header in the case of 22 some sort of failure within the HCUS.

23 MEMBER BALLINGER: Oh, but this, look, 24 okay, now I guess I'm demonstrating my ignorance.

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

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34 1 can't shut the darn thing off, the alternate rod 2 insertion system, in this case, would be called upon 3 to operate in a different way?

4 MR. HINDS: It is quite similar to the, 5 that one feature is quite similar to the existing 6 fleet. And that feature, again, is to, in the case we 7 postulate many different failure modes for the reactor 8 scram.

9 And one of the potential failure modes, 10 not probably, but potential, is the failure of the 11 hydraulic control units to reposition and allow the 12 high pressure water to insert, hydraulically, to 13 control rods.

14 If that were to occur, we'd have the means 15 to depressurize the scram air header, which causes the 16 HCUS to reposition in an alternate way.

17 CHAIRMAN MARCH-LEUBA: Right. I believe 18 you have a diagram on the closed slides, which would 19 be --

20 MR. HINDS: That is correct.

21 MEMBER BALLINGER: Yes.

22 CHAIRMAN MARCH-LEUBA: -- a better time to 23 address it, because we're running late guys.

24 MR. HINDS: Okay.

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

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35 1 minutes.

2 MR. HINDS: Okay.

3 CHAIRMAN MARCH-LEUBA: And we are running 4 proprietary information. So keep going.

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

6 Okay, we'll I'll keep moving, and we'll get back to 7 your questions. I've got many notes here.

8 So, Defense Line 4B is our deep defensive 9 layer. We call it things such as FLEX, just to get 10 you a realm of, when we, if we were, we even do 11 postulate transition into extreme events or severe 12 accidents, and that's where we enter that 4B.

13 We really do not features to highlight 14 today in this topical report related to 4B. I'm just 15 letting you know the big picture.

16 So if we could keep going please. Okay.

17 All right, could you advance, George. Okay. Okay, 18 keep going.

19 Okay, so we did show some visuals in this 20 non-proprietary segment. These are visuals that we've 21 previously shown, but we have some others in our 22 proprietary version that we did not include in this 23 segment.

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

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36 1 just a visual showing the control rod blades.

2 And the control rods are positioned in-3 between the fuel bundles, four fuel bundles in a cell.

4 And that's where I was talking about we have ample 5 space for these control rods to move within these fuel 6 bundles. Just a quick introduction. Next.

7 CHAIRMAN MARCH-LEUBA: Is this drawing on 8 the right to scale that shows that much clearance 9 between the rod, between the blade and the bow?

10 MR. HINDS: I'm now sure, I'd have to 11 double check. It's not bad but it's, this is a 12 PowerPoint presentation so I cannot claim that it's to 13 scale.

14 CHAIRMAN MARCH-LEUBA: Okay. It's not to 15 scale but close. Keep going.

16 MR. HINDS: Yes, I think it's a reasonable 17 representation, but I can't claim it's to scale.

18 Okay. This is just showing, this is the 19 top view of the core. So it's just showing, just 20 giving you a big picture here.

21 We have many control rods. So, basically 22 you have 57 control rods in this core. And so, even 23 if one, or even more were to fail, we'd still have 24 ample means to control reactivity of this core.

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

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37 1 our proven fuel.

2 I've already mentioned several of these 3 topics here, but again, we have much experience with 4 the fine motion control rod drives, it's not just a 5 brand new invention.

6 It does, they do operate by hydraulic 7 force for scram. And normal movement, day in, day 8 out, is with the fine motion motors.

9 So, there is hydraulics that insert 10 rapidly in the case of the need for a scram, and there 11 is motors that move in day in and day out. The motors 12 provide a fine means of control, but they also provide 13 diverse needs of insertion.

14 The ARI that we mentioned previously is a 15 diverse means to actuate the hydraulics. Again, we'll 16 show you the figure in a little while, as was 17 mentioned.

18 Some might be familiar of the history of 19 the BWRs where we've been using hydraulics for a long 20 time for control rod movement. But the hydraulics on 21 the older plants that did not have motors attached to 22 the control rod drives, they have a scram discharge 23 volume as well.

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

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38 1 all that's applied, there are no hydraulics for 2 withdrawal.

3 And so, in the previous locking piston 4 control drives, which are still successfully in 5 service in the fleet, there is a scram discharge 6 volume which allows for an exhaust on the top side of 7 the piston. That is not present in the BWRX-300, or 8 in any of our FMCRDs.

9 There are some failure modes that we've 10 combated over the years with our scram discharge 11 volume. Elimination of that scram discharge volume 12 eliminates a potential failure mode of the hydraulics.

13 So I'm just mentioning that from the 14 standpoint of another of, I've been saying these 15 words, increased reliability. That's one way of 16 increasing reliability of the hydraulics. And then we 17 additionally have diversity and redundancy.

18 Okay, George.

19 MEMBER BLEY: So, David, that implies 20 there is an open release pass for where the scram 21 discharge volume needs to be, is that right?

22 MR. HINDS: Yes. It basically just goes 23 into the reactor vessel.

24 MEMBER BLEY: Okay.

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

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39 1 push it in and the water has enough flow by internals 2 in the FMCRD to go into the reactor vessel.

3 Okay. So, just a related, but a little 4 different, this is just the cut away of the reactor 5 pressure vessel. It is, because it's the natural 6 circulating plant, we alluded to this in our, or we 7 covered this in our first LTR, which we previous 8 presented.

9 But the large volume, or relatively large 10 volume, for the purpose of natural circulation had 11 advantages of, that steam volume allows for a lower 12 pressurization rate in events. And, again, we 13 covered, I've listed the reference of the previous 14 LTR. I won't go into details here since we've already 15 covered.

16 Okay, George. And we've also covered this 17 in our prior LTR but I'm mentioning it again because 18 it is pertinent to mitigating failures within 19 reactivity control.

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

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40 1 is our Safety Class 1 safety related heat removal 2 system.

3 So, in the event of an isolation event, 4 the energy is removed by the isolation condenser 5 system by taking steam condensing in pools. Similar 6 to the design that was implemented on the ESBWR, and 7 then returned the condensate back to the reactor 8 vessel, limits reactor pressure and provides for a 9 passive means of cooling.

10 Once actuated, no further means for any, 11 there's a valve that has to open to open the flow 12 path. And once actuated, it needs no further support 13 system other than just that pool that heat exchangers 14 are immersed in.

15 Okay.

16 MEMBER REMPE: So this --

17 (Simultaneous speaking.)

18 DR. CORRADINI: This is Corradini.

19 CHAIRMAN MARCH-LEUBA: Okay, Mike.

20 DR. CORRADINI: I guess maybe we should 21 wait till the closed session, just so you can confirm 22 it, but I have a number of questions about this 23 cartoon, so, since it's a cartoon should we wait till 24 closed to ask detailed questions?

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

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41 1 great. Because we're running a little behind.

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

3 I'll wait.

4 MR. HINDS: Great. Thank you.

5 MEMBER REMPE: So I have one quick 6 question though. Is the water level, this water level 7 differs from what we were shown in the open sessions 8 or closed sessions in prior discussions of this plant.

9 Is the water levels substantially above 10 where the piping is?

11 MR. HINDS: Yes. The water level, meaning 12 the piping, meaning the condensate return? Yes.

13 MEMBER REMPE: Right. Because that's, 14 thank you.

15 MR. HINDS: I'll get back to that in the 16 closed session. In case I didn't answer your 17 question, please ask again in the closed session.

18 CHAIRMAN MARCH-LEUBA: Yes. One thing you 19 didn't mention is the size of the ICS. We mentioned 20 in the previous, this is grossly over designed?

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

22 It's got a large capacity. So yes, it's capable for 23 controlling reactor pressure.

24 CHAIRMAN MARCH-LEUBA: Okay, thank you.

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

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42 1 mention, and I think the NRC will cover in more 2 detail, possibly, on the regulatory side of the 3 review. And, George or Lou, if you have anything to 4 interject please do.

5 So, some of the associated regulations and 6 regulatory guidance that we covered in this licensed 7 topical report, of course, there is 10 CFR 50.62 for 8 the ATWS event.

9 And we just highlight a point here that 10 the, the ATWS rule was written at a time when these 11 multiple defense-in-depth features, that I was 12 describing and just giving a brief intro here, were 13 not all present.

14 And so we feel that the, and I also 15 alluded to reliability, you asked me about, that the 16 added defenses, defense line features that we have 17 implemented with BWRX-300 will result in a lower 18 frequency of occurrence of that postulated event 19 sequence, complex sequence of an ATWS. So, things 20 have changed significantly.

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

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43 1 as stated in the intent of the ATWS rule. So just a 2 little background, okay.

3 George. All right. And here is some 4 review guidance that we also referenced. I know its 5 review guidance, but we referenced it to help align 6 with the expectations.

7 In the SRP 15.8 there is statements about 8 evolutionary plants, which this plant is. Then we 9 will tell you some more in the closed session about 10 diverse features, so I'm just highlighting that point 11 that in the SRP there is some mention of, and that a 12 mitigating strategy could be to add diverse features.

13 Again, we protected some of the details of 14 our diverse features. I just briefly introduced them.

15 We'll come back to them, but we do have diverse 16 features in this plant is really the point I'm trying 17 to get at.

18 Okay. We do have alternate means for 19 shutdown. We do have alternate rod insertion, which 20 is explicitly called out in the rule.

21 We do have electric motors to insert the 22 control rods that are independent of the hydraulic 23 insertion method. We do have multiple means of 24 shutting down the plant.

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44 1 those in each of our defense line type of approach.

2 If a failure occurs in one defense line or a failure 3 occurs in multiple defense lines.

4 Okay. So we, 50.62 mandates reduction of 5 risk from an ATWS. We think we have done that. And 6 we will continue to supply information to further 7 prove that, such as what was asked a little while ago, 8 is about the PRA.

9 During a license submittal for a plant, we 10 would submit the PRA as expected. And if it proves 11 out that we have reduced the risk of an ATWS as called 12 out by this rule.

13 They require ARI. I mentioned before we 14 have it. Require SLC, we'll cover further in a little 15 while. And requires automatic recirc pump trip.

16 Okay, George. Okay, so, I've already 17 mentioned most of this. Each control rod contains 18 certified hydraulics. And the hydraulics can also be 19 actuated by its normal means, but also actuated 20 mechanically by the ARI.

21 Also, the motors, I've mentioned several 22 times, provide a diverse means for insertion. We 23 think those are key features for evaluating the ATWS 24 rule.

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45 1 between the control systems associated with the normal 2 means of scram and the alternate means of scram.

3 Eliminates common mode failures by having 4 these diverse means. Or eliminates at least having 5 the effects of the common mode failure of inability to 6 shut the plant down.

7 And I already mentioned the scram 8 discharge volume was removed, so that failure mode is 9 an example of one that was just completely removed.

10 SLC, we eliminated the failure of control 11 rod insertion from a single common cause failure so we 12 used a defense-in-depth approach. We'll talk a little 13 more about, more details associated with SLC because 14 we had that in the second session. Okay.

15 CHAIRMAN MARCH-LEUBA: Dave. No, go back 16 to the Slide 30.

17 That statement, I don't see you have 18 eliminated the failure. What you can say is that we 19 have looked very hard and haven't found, found one 20 yet.

21 MR. HINDS: Okay.

22 CHAIRMAN MARCH-LEUBA: Do you agree on 23 that?

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

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46 1 to claim that the probability of ATWS is so small that 2 we don't have to worry about it. Are we going to 3 analyze it and demonstrate that nothing breaks? Within 4 the relaxed ATWS criteria, which are very relaxed, 5 basically comparability.

6 Because one concern I have is ATWS over 7 pressure. There are some special features that the 8 pressures in ATWS might, it still needs to be 9 calculated.

10 MR. HINDS: Yes.

11 CHAIRMAN MARCH-LEUBA: So what is your 12 path, A or B?

13 MR. HINDS: So, let's see if this at least 14 partially addresses your question. And again, part of 15 our details of thermal hydraulics we had planned for 16 the segment, as needed.

17 But we did analyze failure of the normal 18 scram system and the associated reactor and pressure 19 transient that occur as a result of failure of the 20 normal scram system.

21 We did, in that analysis, credit some of 22 the diverse means as mitigation. But we did analyze 23 the pressure response and have acceptable results to 24 the pressure response on the failure of the normal 25 scram system.

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47 1 DR. CORRADINI: I'm, this is Corradini, 2 can you repeat that, I don't think I appreciate what 3 you just said?

4 CHAIRMAN MARCH-LEUBA: Yes, I was going to 5 suggest, and it was me, let's delay this till the 6 closed session because we have to talk about this, 7 especially mitigation features and all that.

8 MR. HINDS: Okay. Yes, I think that's, I 9 would appreciate that.

10 CHAIRMAN MARCH-LEUBA: Yes.

11 MR. HINDS: Okay. Thank you. I 12 understand your question.

13 Okay, so I mentioned this but I this is, 14 hopefully, an easy one. But this plant has no 15 recirculating pumps. No recirc pumps.

16 It's a natural circulating power plant so 17 the prescriptive rule for tripping the recirc pumps is 18 not technically relevant to the BWRX-300. However, we 19 do consider what was the fundamental purpose of doing 20 that in reducing the overall reactivity.

21 And we have other features for ensuring 22 that we reduce the reactivity. But we do not have 23 recirc pumps to trip.

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

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48 1 this that clearly is not applicable, do we need an 2 exemption because the recirculation pump trip is 3 easily called up in the rule.

4 So does this have a mechanic, a proceed 5 here that I think is obvious what the answer is. But 6 maybe I'll ask the Staff whether we need an exemption 7 from 50.62.

8 MR. HINDS: Okay. Would you like for me 9 to keep proceeding and wait for the --

10 CHAIRMAN MARCH-LEUBA: Yes, please.

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

12 CHAIRMAN MARCH-LEUBA: Yes. Yes, go 13 ahead.

14 MR. HINDS: Okay, thank you. Okay, so, 15 again, we'll talk some more, as you just mentioned, 16 about the analyses results in our next segment. But 17 we did use the regulatory acceptance criteria from the 18 rule and from the regulations. And we just listed 19 some of them here.

20 Nothing we've changed anything here, it's 21 just restating some. So, if you have questions or 22 would like me to elaborate, please let me know.

23 Otherwise we're just recognizing that we understand 24 and will maintain the regulatory acceptance criteria.

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49 1 criteria level. So, within GDC27 we did, because of 2 the wording of the GDC, we did have some proposed PEC.

3 And that's included in the LTR. It's related to our 4 means of reactivity control during a failure to scram.

5 But we do maintain core coolability. And 6 there is just this portion related to pose an addition 7 by ECCS. It's not relevant to this plant and that's 8 what resulted in the PEC. I think we have more slides 9 on this but --

10 MR. WADKINS: Yes, later.

11 MR. HINDS: Okay. Then we'll come back to 12 that a little bit later. And I think the Staff will 13 cover some as well.

14 MEMBER REMPE: So, at this point, Jose, 15 I'd like to come back to my very first question.

16 I've heard that there is a September 2020 17 version of this LTR that's been with the, had the 18 revisions from the RAIs incorporated.

19 MS. FRANOVICH: That's correct.

20 MEMBER REMPE: We only have the March 2020 21 version of it. And that's a shame but since we've 22 been given the March 2020 version, can we be provided 23 the September 2020 version, not only the clean copy 24 but also some way that shows track changes so we don't 25 have to go through and re-review everything?

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50 1 But I just think that the changes were 2 sufficiently substantial. That it would be good for 3 us to see how it is cast at this time.

4 MS. FRANOVICH: This is Rani Franovich, 5 the project manager. In the SE the Staff wrote an 6 introduction that explained that there was a 7 supplement to the original SE that was provided on 8 September 4th, 2020.

9 The accession number is provided in the 10 introduction. We do not have a track changes version, 11 but there is, in the document that was submitted by 12 GEH, a table, as I recall, that described the changes 13 that were made.

14 George, can you confirm that?

15 MR. WADKINS: Yes, that is true. The 16 Supplement 1 does have a revision record which 17 explains the changes. They were, I believe in this 18 supplement, they were entirely from that one set of 19 RAIs.

20 MEMBER REMPE: So, please get that to Zena 21 and have her, she'll distribute it to us soon because 22 we, I missed it that this Supplement 1 existed. And, 23 again, I just checked our share point site, we only 24 have the March 2020 version out there.

25 MS. FRANOVICH: Understand.

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51 1 MEMBER REMPE: Do you have the September 2 version, Jose?

3 CHAIRMAN MARCH-LEUBA: No, I don't. I 4 know you asked this last week, or two weeks ago, and 5 I was not aware.

6 MEMBER REMPE: No. Okay, so please get 7 that to us. Thank you.

8 MR. WADKINS: Okay, thanks, David. If 9 there are no further questions then I wish to thank 10 the NRC Staff once again and the ACRS Members for 11 their time.

12 We will discuss some of these items that 13 we tabled in the closed session. But again, if there 14 are no additional questions we will turn this over to 15 the NRC Staff to present their SER.

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

17 I'm going to share my screen. And if I could get some 18 feedback that you guys, everyone can see it, that 19 would be great.

20 CHAIRMAN MARCH-LEUBA: We can see the 21 screen, but the slide is all garbled. You need to put 22 the slides on top.

23 MS. FRANOVICH: I'm trying to, I'm trying 24 to do that as we speak. Bear with me. Huh. Can 25 everyone see that?

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52 1 CHAIRMAN MARCH-LEUBA: Yes. Now it's 2 perfect.

3 MS. FRANOVICH: Thank you. All right, 4 Ryan, I will turn this over to you to start the 5 Staff's presentation.

6 MR. NOLAN: Thank you, Rani. This is Ryan 7 Nolan. I am in NRR in the Nuclear Methods Systems and 8 New Reactor Branch and I will be presenting a brief 9 overview of our safety evaluation in the open session.

10 A lot of the underlying material in which 11 we made our findings is based on proprietary 12 information, so a good portion of our discussion will 13 have to be in the closed session.

14 Rani, you can go to the next slide. So, 15 in this presentation I'm going to briefly go over who 16 the review team was, a brief background on the BWRX-17 300, as well as our review of NEDC-33912 and then I'll 18 wrap up with our conclusion.

19 So, in addition to myself, my colleagues 20 Andrew Proffitt and Alex Siwy will be co-presenting in 21 the closed session with me.

22 And we also had some support from 23 additional tech staff and other disciplines who are 24 available to answer any questions that come up in 25 their area. However, there is no specific slides.

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53 1 And I'll address that when we get there.

2 Rani, you can go to the next slide. So, 3 a very brief background. The BWRX-300, it's a 300 4 megawatt electric SMR, uses natural circulation.

5 Passive cooling is provided by the isolation condenser 6 system and it's based on the SBWR design.

7 As GEH has already presented, they use 8 typical BWR bottom entry control rods. The design 9 does include defense-in-depth and diverse features for 10 shutting down the reactor and controlling reactivity.

11 And this topical report that we are 12 describing provides design requirements, as well as 13 assessments regulatory requirements, related to 14 reactivity control.

15 Next slide, Rani. The topical report 16 specifies design requirements for the control system, 17 RPS as well as alternate rod insertion system.

18 There's a couple others there. We will be 19 going into much more detail on these systems in the 20 closed session.

21 Go to the next slide, Rani. Here's the 22 list of the regulations we evaluated as part of the 23 topical report.

24 The focus is on 50.62. The ATWS rule.

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54 1 does address a long list of GDCs.

2 The GDCs that are underlined in this slide 3 will be presented in the closed session in much more 4 detail. The GDCs which are not underlined, we do not 5 have any specific slides on so now would be probably 6 the right time to ask any questions on these 7 particular GDCs.

8 But in the interest of time, GEH's 9 approach that they described for meeting these GDCs, 10 which are not underlined, seemed fairly typical and 11 traditional. And our overall conclusion, specific to 12 these GDCs, is that the approach is consistent with 13 how they have it implemented historically. So there 14 are no specific slides on the GDCs which are not 15 underlined.

16 And if there is no questions, I'll think 17 we'll just wrap up the conclusion on the next slide, 18 Rani.

19 We did write a few limitations and 20 conditions in our safety evaluation for this topical 21 report. These were mainly in areas where the topical 22 report, it didn't really specify what form of analysis 23 will be performed in the future to demonstrate 24 compliance with the regulation.

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

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55 1 conditions sort of establishing the analysis the Staff 2 expects that would be included in a future licensing 3 submittal. So it's really more of just a 4 clarification of our expectations.

5 In conclusion, we did find that the 6 topical report provided an acceptable description of 7 design requirements, the acceptance criteria and the 8 regulatory basis for the BWRX-300 reactivity control 9 functions and features.

10 And as a disclaimer, the detailed design 11 of the BWRX-300 SMR is not complete. And the Staff 12 does expect that an applicant demonstrate compliance 13 with the regulations. And if they cannot demonstrate 14 compliance, we do expect an adequate justification for 15 an exemption.

16 And with that, the Staff will evaluate any 17 regulatory compliance, with the final design, when we 18 receive an application in the future. And that's all 19 I had for the open presentation.

20 CHAIRMAN MARCH-LEUBA: Ryan, this is Jose 21 again. GE went into some detail under the GDC 27 22 issue, but can you say in open session whether there 23 is an issue with return to power when the control was, 24 not in ATWS, but when control rods go in and two rods 25 remain stuck.

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56 1 MR. NOLAN: Yes. My understanding of the 2 design is that it is capable of maintaining the 3 reactor shutdown, assuming a single failure of the 4 worst rod pair. So they, my understanding is, with 5 two rods out the reactor will remain shut down.

6 CHAIRMAN MARCH-LEUBA: Of co-conditions 7 and --

8 MR. NOLAN: Yes.

9 CHAIRMAN MARCH-LEUBA: -- CW3?

10 MR. NOLAN: That is --

11 CHAIRMAN MARCH-LEUBA: Okay. So there is 12 no issue with return to power?

13 MR. NOLAN: No. Oh, and then with respect 14 to your question on 50.62(c)(5), which is the 15 requirement for an automatic recirc pump trip, and the 16 question was whether an exemption is needed or not, 17 our position is that it is not applicable and an 18 exemption is not needed.

19 It's a natural circulation plant, they 20 don't have recirc pumps. And so that particular 21 regulation is not applicable, no exemption is needed.

22 However, we do expect, we will review any 23 compensating measures that are taken to address that.

24 Maybe the intent behind that role. And this is 25 consistent with what was done for the ESBWR.

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57 1 CHAIRMAN MARCH-LEUBA: So that's good.

2 That's a good answer. I wouldn't even call it 3 transformational.

4 Yes, we don't need to do work when no work 5 is needed. If we can say, duh, it's obvious, we can 6 save a month of work.

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

8 CHAIRMAN MARCH-LEUBA: Thank you. So, are 9 you done with, the Staff is done with the 10 presentation?

11 MR. NOLAN: Yes. That concludes my 12 presentation.

13 CHAIRMAN MARCH-LEUBA: So this concludes 14 the complete open session presentation. Can we open 15 the phone line please?

16 At this point, anybody in the public, on 17 the phone line, that wants to make a comment, please 18 state your name and make your comment. Is the phone 19 line open? Public phone line?

20 MEMBER BROWN: Hello?

21 CHAIRMAN MARCH-LEUBA: Yes.

22 MEMBER BROWN: Jose? Jose?

23 CHAIRMAN MARCH-LEUBA: Yes.

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

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58 1 other than my cell phone, which has no coverage.

2 Almost. I'm probably going to trip off. Hind winds 3 and something is going down, so I won't be back in 4 until I can get some power.

5 CHAIRMAN MARCH-LEUBA: All right, it's 6 okay. Thank you for letting us know.

7 MEMBER BROWN: Okay. Yes, thank you.

8 Take care.

9 CHAIRMAN MARCH-LEUBA: Any other comments?

10 All right, we'll assume the public doesn't have any 11 more comments.

12 Any Members of the Committee want to make 13 a comment on the record, at this moment?

14 MEMBER KIRCHNER: Jose, this is Walt 15 Kirchner. Just an observation, maybe for David from 16 GE to answer.

17 He explicitly, I know that this topical 18 report is about the activity control and design 19 requirements, but under Defense Line 3 he has the 20 reactor protection system scram and the isolation 21 condensing system. I would assume then the RPV is 22 also in that category, is that correct?

23 That's more of a question or a 24 clarification for GEH.

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

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59 1 we need to ask that question in closed session.

2 Because we'll get into details of their proprietary 3 design. If you don't mind --

4 MEMBER KIRCHNER: Oh, sure. No, that's 5 fine. It's just more an observation.

6 CHAIRMAN MARCH-LEUBA: Yes. Yes, thank 7 you. Any other comments or questions? Hearing none, 8 we are going off the record.

9 (Whereupon, the above-entitled matter went 10 off the record at 10:46 a.m.)

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ACRS Subcommittee Presentation GEHitachi (GEH)

Licensing Topical Report (LTR) NEDC33912P BWRX300 Reactivity Control (Open Session)

November 2, 2020

Agenda (Open Session)

Licensing Topical Report Purpose and Scope Defense in Depth Design Features for BWRX300 Reactivity Control Summary of Design Features to Meet Regulatory Requirements and Provide Defense in Depth for Reactivity Events Regulatory Evaluation Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 2

Licensing Topical Report Purpose and Scope Licensing Topical Report Purpose and Scope Provide the design requirements, acceptance criteria, and regulatory basis for the BWRX300 RPS and other associated means of reactivity control:

BWRX300 means of reactivity control design functions

- Specify design requirements for the RPS to ensure regulatory requirements are met

- Specify design requirements for other means of reactor shutdown to ensure that defense in depth diversity requirements are met

- Specify design requirements for other functions such as Alternate Rod Insertion to ensure the hydraulic scram meets reliability requirements

- Specify BWRX300 acceptance criteria and associated mitigating strategy in response to an ATWS as evaluated against 10CFR50.62

- Describe compliance with the requirements of 10 CFR 50 Appendix A, General Design Criteria (GDC) 12, GDC 20, GDC 21, GDC 22, GDC 23, GDC 24, GDC 25, GDC 26, GDC 28, and GDC 29

Licensing Topical Report Purpose and Scope Provide the design requirements, acceptance criteria, and regulatory basis for the BWRX300 mitigating systems associated with an ATWS:

BWRX300 mitigating systems associated with an ATWS

- Specify design requirements for systems to control reactor pressure during an ATWS

- Specify design requirements for additional means of reactor shutdown in the case of failure of all means of hydraulic insertion of control rods

- Specify BWRX300 acceptance criteria and associated mitigating strategy in response to an ATWS as evaluated against 10CFR50.62 Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 5

Defense in Depth Design Features for BWRX300 Reactivity Control

Defense in Depth Design for BWRX300 BWRX300 applies a defense in depth approach aligned with the IAEA guidance

Address fundamental safety functions to ensure overall plant safety

Assigns BWRX300 functions to defense lines associated with fundamental safety functions

This LTR is focused on the fundamental safety function of reactivity control

Defense in Depth - Defense Line 1 IAEA Defense Line 1:

Level 1

Reduce challenges to the Reactor Protection System from all occurrences Defense Line 1 (DL1)

- Fewer trips per year

- Reduces number of AOOs

Some transients become Infrequent Events defined as < 1 per 100 Reactoryears

Strengthen subsequent lines of Defense

- Quality

- Reliability

Defense in Depth - Defense Line 1 IAEA Defense Line 1 Examples:

Level 1

Technical Specification operational controls

NLattice core less likely to experience control rod binding Defense Line 1 (DL1)

Advances in channel materials and core design/operation minimize probability of channel bow

Normal power changes are with control rods - continuous observation of normal function

Reliability measures included in design minimize probability of Postulated Initiating Events (PIEs) and failure of mitigation

Defense in Depth - Defense Line 1 IAEA Defense Line 1 Examples:

Level 1

Seismic qualification ensures core geometry maintained

FMCRDs similar to ABWR and ESBWR Defense Line 1 (DL1)

Control Rod Blades

- Same as ABWR

- Almost identical to latest design for BWR fleet

Defense in Depth - Defense Line 2 IAEA Defense Line 2:

Level 2

Includes functions which normally control the plant

Plant functions designed to control or stop a PIE Defense Line 2 (DL2)

Minimizes PIEs that reach DL3 setpoints

Defense in Depth - Defense Line 2 IAEA Defense Line 2 Mitigation:

Level 2

Diverse means to shutdown

Other diverse system actuations Defense Line 2 (DL2)

Control of power generation systems can assist with mitigation of failures within shutdown systems

Defense in Depth - Defense Line 3 IAEA Defense Line 3:

Level 3

Includes functions which act to mitigate a PIE

Ensure plant is placed in a safe state Defense Line 3 (DL3)

Assigned to highest safety class

Defense in Depth - Defense Line 3 IAEA Defense Line 3 Mitigation:

Level 3

Reactor Protection System (RPS) Scram

Isolation Condenser System Defense Line 3 (DL3)

Defense in Depth - Defense Line 4a IAEA Defense Line 4a:

Level 4

Includes functions to mitigate a PIE along with failure of DL3 Defense Line 4a (DL4a)

Mitigates CCFs in DL3

Defense in Depth - Defense Line 4a IAEA Defense Line 4a Mitigation:

Level 4

Alternate Rod Insertion (ARI) - provides hydraulic scram in event Defense Line 4a (DL4a) of Hydraulic Control Unit (HCU) actuation failure

Defense in Depth - Defense Line 4b IAEA Defense Line 4b:

Level 4

Functions to prevent or mitigate severe accident Defense Line 4b (DL4b)

Defense in Depth - Defense Line 4b IAEA Defense Line 4b Mitigation:

Level 4

The need for features in DL4b will continue to be evaluated Defense Line 4b (DL4b) through the Probabilistic Risk Analysis (PRA) event sequences analyses Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 18

Design Features to Meet Regulatory Requirements and Provide Defense in Depth for Reactivity Events

BWRX300 Control Rod with Fuel Assemblies

BWRX300 Core with Control Rods

NLattice core provides ample space for control rod travel

FMCRD

FMCRDs are evolution from BWR fleet hydraulic control rod drives

Motor provides normal means of control rod movement

Hydraulic scram diverse from motor driven movement

FMCRDs proven in operating ABWRs

Driven by failsafe Hydraulic Control Units (HCUs)

ARI valves provide diverse means to release stored energy

BWRX300 Reactor Pressure Vessel (RPV)

Large RPV steam volume results in lower pressurization rate for isolation events (compared to ABWR and existing BWRs) hence resulting in less reactivity effect

BWRX300 Design Features ICS

Heat exchanger design and capacity of each ICS train is the same as ESBWR

Failsafe, simple system

Limits reactor pressure and temperature and maintains reactor water inventory

Compliance to Regulatory Requirements Applicability of 10CFR50.62 to Evolutionary Plants During the ATWS rulemaking the NRC staff set a goal that frequency of an ATWS should be no more than 1.0E05/reactoryear NUREG1780 Using operating data since the ATWS rule was implemented, found that on a generic basis, all four reactor types achieved the ATWS rule risk goal.

Design Features Described in Standard Review Plan (SRP)

NUREG0800, SRP 15.8, states the following:

A. For evolutionary plants where the ATWS rule does not explicitly require a diverse scram system, the applicant may provide either of the following:

i. A diverse scram system satisfying the design and quality assurance criteria specified in SRP Section 7.2 ii. Demonstrate that the consequences of an ATWS event are within acceptable values BWRX300 meets both requirements

Alternate means for shutdown

ARI and electric motor runin included in DL4a

Successful scram ensured by DL2, DL3, DL4a

Design Features Required by ATWS Rule 10 CFR 50.62 mandates reduction of risk from an ATWS 10 CFR 50.62(c)(3), (4) and(5) require the following design features for BWRs:

Alternate Rod Insertion (ARI) System

Automatic SLCS

10 CFR 50.62(c)(3) - Alternate Rod Insertion (ARI) System Each control rod can be inserted hydraulically using either of two methods:

RPS actuated HCUs to release stored highpressure water from accumulators

Diverse ARI pilot valves on control air header for scram valves to release stored energy for scram Additionally FMCRDs have electricmotordriven positioning used for both insertion and withdrawal of the control rods Electric motor diverse from the hydraulic scram feature

Allows rod movement, even with failure of ARI system

Utilize sensors and logic that are diverse and independent of the RPS Eliminated common mode failure of hydraulic scram by eliminating the scram discharge volume Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 29

10 CFR 50.62(c)(4) - Automatic SLCS BWRX300 Design has eliminated failure of control rod insertion from a single common cause

Uses the Defense in Depth approach delineated in IAEA SSR2/1 to provide multiple layers of defense to ensure reactor is shutdown Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 30

10 CFR 50.62(c)(5) - Automatic Recirculation Pump Trip Forced circulation BWRs trip recirculation pumps to reduce core flow and power:

BWRX300 utilizes natural circulation and has no recirculation pumps BWRX300 design also utilizes:

Control of power generation systems to assist in mitigation

Regulatory Acceptance Criteria Primary System Maximum primary stress within (RCPB) does not exceed the emergency limits as defined in the ASME B&PV Code,Section III Fuel Integrity Cladding temperature and oxidation criteria of 10 CFR 50.46 met Containment Integrity Maximum containment pressure does not exceed the design pressure Radiological Releases Maintained within 10 CFR 100 allowable limit Shutdown and Cooling Reactor is brought to longterm shutdown with continued effective core cooling Copyright 2020 GE Hitachi Nuclear Energy Americas, LLC - All Rights Reserved 32

10 CFR Part 50, Appendix A, GDC 27 10 CFR Part 50, Appendix A, GDC 27, Combined Reactivity Control Systems Capability The reactivity control systems shall be designed to have a combined capability, in conjunction with poison addition by the emergency core cooling system, of reliably controlling reactivity changes to assure that under postulated accident conditions and with appropriate margin for stuck rods, the capability to cool the core is maintained

Exception Core coolability is maintained for lossofcoolant accidents because loss of water inventory in the RPV is minimized by the assured function of RPV isolation valves to mitigate large line breaks

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

Presentation Outline

NRC Staff Review Team

BWRX-300 Background

NRC Staff Review of NEDC-33912P

Conclusion 2

NRC Staff Review Team

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

BWRX-300 Background

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 Reactivity Control Systems and Functions NEDC-33912P specifies design requirements for:

Rod control system

Reactor protection system

(( ))

Alternate rod insertion

(( ))

5

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.

Proprietary Information 7

Questions?

Proprietary Information 8

ML20344A443

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