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{{#Wiki_filter:Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
{{#Wiki_filter:}}
 
==Title:==
Advisory Committee on Reactor Safeguards Future Plant Designs Subcommittee Docket Number:    (n/a)
Location:        teleconference Date:            Tuesday, July 20, 2021 Work Order No.:  NRC-1595                          Pages 1-109 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                FUTURE PLANT DESIGNS SUBCOMMITTEE 8                                + + + + +
9                                  TUESDAY 10                            JULY 20, 2021 11                                + + + + +
12                  The Subcommittee met via Videoconference, 13 at 9:30 a.m. EDT, Peter Riccardella, Chair, presiding.
14 15 COMMITTEE MEMBERS:
16            PETER RICCARDELLA, Chair 17            RONALD G. BALLINGER, Member 18            VICKI M. BIER, Member 19            CHARLES H. BROWN, JR. Member 20            GREGORY H. HALNON, Member 21            WALTER L. KIRCHNER, Member 22            JOSE MARCH-LEUBA, Member 23            DAVID A. PETTI, Member 24            JOY L. REMPE, 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 CONSULTANT:
2            STEPHEN SCHULTZ 3
4 DESIGNATED FEDERAL OFFICIAL:
5            KENT HOWARD 6
7 8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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3 1                        C-O-N-T-E-N-T-S 2                                                                PAGE 3 Opening Remarks by Peter Riccardella, ACRS              . . .      4 4 Staff Remarks by Louise Lund, RES . . . . . . . .                    7 5 NRC Staff Presentation 6 Overview of ASME Code Section III, 7 Division 5    . . . . . . . . . . . . . . . . . . . 10 8 NRC Staff Presentation 9 Staff Efforts on Potential Endorsement 10 of ASME Code Section III, Division 5              . . . . . . 67 11 Adjourn . . . . . . . . . . . . . . . . . . . .                  109 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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4 1                    P R O C E E D I N G S 2                                                            9:30 a.m.
3                CHAIR RICCARDELLA:            This is a meeting of 4 the Future Plant Designs Committee.                The meeting will 5 now come to order. I am Pete Riccardella, Chairman of 6 this meeting.      ACRS members in attendance are Ron 7 Ballinger, Dave Petti, Joy Rempe, Walt Kirchner, Vicki 8 Bier, Matt Sunseri, Greg Halnon, and Charles Brown.
9 Is our consultant, Steve Schultz -- are you on the 10 meeting?
11                (No response.)
12                CHAIR    RICCARDELLA:            Okay. Steve      was 13 expected to join.      He might be on soon.
14                DR. SCHULTZ:        I'm here, Pete.
15                CHAIR    RICCARDELLA:              Okay. And      our 16 consultant, Steve Schultz, is also in attendance.
17 Kent Howard of the ACRS staff is the Designated 18 Federal Official for this meeting.
19                The  purpose      of  today's      meeting    is    an 20 information briefing from the NRC staff on potential 21 endorsement of ASME Section III, Division 5, High 22 Temperature Reactors.          The subcommittee will gather 23 information, analyze relevant issues and facts, and 24 formulate      proposed      positions          and    actions        as 25 appropriate.          However,        at      the    subcommittee's NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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5 1 direction,        any  matter        will      be    considered      for 2 presentation at the full committee if necessary as the 3 members see fit.        The ACRS was established by statute 4 and is governed by the Federal Advisory Committee Act, 5 FACA.
6                  The NRC implemented FACA in accordance 7 with regulations found in Title 10 of the Code of 8 Federal Regulations, Part 7.              The committee can only 9 speak to its published letter reports.                        We hold 10 meetings to gather information and perform preparatory 11 work that will support our deliberations at a full 12 committee meeting, if necessary.
13                  The rules for participating in all ACRS 14 meetings, including today's, were announced previously 15 in the Federal Register. The ACRS section of the U.S.
16 NRC      public  website    provides      our      charter,  bylaws, 17 agendas, letter reports, and full transcripts of all 18 full      and  subcommittee      meetings,          including    slides 19 presented there.        The meeting notice and agenda for 20 this meeting were posted there.
21                  Members      of  the    public      who  desire      to 22 provide written or oral input to the subcommittee may 23 do so and should contact a designated federal official 24 five      days  prior    to    the    meeting        as  practicable.
25 Today's meeting is open to the public attendance. And NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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6 1 there will be time set aside during the meeting for 2 spontaneous        comments      from    members      of  the    public 3 attending or listening to our meetings.
4                    Due to the COVID pandemic, today's meeting 5 is being held over Microsoft Teams for ACRS, NRC, and 6 members of the public.                There is also a telephone 7 bridgeline allowing participation of the public over 8 the phone.        This public bridgeline is controlled by 9 the ACRS staff and should not be muted by anyone other 10 than the designated ACRS staff members.
11                    A transcript of today's meeting is being 12 kept.          Therefore,      we  will      request    that  meeting 13 participants on the bridgeline identify themselves 14 when      they  are  asked    to    speak      and to  speak      with 15 sufficient clarity and volume so that they can readily 16 be heard.        At this time, I ask that attendees on the 17 Teams and bridgeline mute their phones to minimize the 18 disruption and to unmute your individual devices only 19 when speaking.
20                    We will now proceed with the meeting.                    I 21 call on Louise Lund, Division Director of the Division 22 of Engineering, Office of Nuclear Regulatory Research, 23 to make introductory remarks.                Louise, are you there?
24                    MS. LUND: Yes, thank you. Thank you, Dr.
25 Riccardella, and good morning to the ACRS members and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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7 1 all others here for this meeting.                      I hope everybody 2 can hear me.        Can I be heard?
3                    CHAIR RICCARDELLA:            You're fine, Louise.
4                    MS. LUND:        Great, wonderful.            So I'm 5 Louise Lund, Director of the Division of Engineering, 6 Office of Nuclear Regulatory Research.                    I also serve 7 as the Agency standards executive for the codes and 8 standards          program,        coordinating          the    Agency 9 participation          on    various        standard      development 10 organization committees, and assuring Agency goals and 11 activities        relative      to    staff        participation      and 12 development and use of consensus standards.
13                    On  behalf    of    the    staff,    we  are    very 14 pleased to have the opportunity to present on the 15 review and potential endorsement of the ASME Boiler 16 and Pressure Vessel Code, Section III, Division 5, 17 high temperature reactors.                As you know, the NRC is 18 executing its vision to become a modern risk informed 19 regulatory by developing approaches to streamline and 20 optimize reviews to enable the deployment of advanced 21 reactor technologies.            As part of the vision, the NRC 22 developed implementation action plans for various 23 strategic areas.
24                    Consistent with its implementation action 25 plans,        NRC  has  been    working        proactively    towards NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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8 1 enhancing        its    non-LWR        technical        readiness        and 2 optimizing regulatory readiness. Today's presentation 3 will be part of Strategy 4 which aims at facilitating 4 development of industry codes and standards.                                To 5 further that objective, the staff developed a prudent 6 and balanced approach to ensure efficient completion 7 of the endorsement project.
8                  The  approach        involved        building      staff 9 knowledge        through      training          and    collaborative 10 activities, active participation in the ASME Section 11 III working groups, engaging contractors to perform 12 reviews and provide recommendations, and performing 13 independent        assessment        of    the      code    rules      and 14 procedures          and      contractor            recommendations.
15 Recognizing        that  the    technical          expertise    on    high 16 temperature materials and components for advanced non-17 light water reactors was largely confined to a small 18 group        of people    who    were      involved      in  the      code 19 development.        But staff engaged these experts to seek 20 clarification on staff's assessment and contractors' 21 recommendations where applicable.
22                  With such a comprehensive approach, the 23 staff has pursued a holistic and balanced endorsement 24 of the ASME Section III, Division 5 code. This review 25 represents        a  major    collaborative          and  successful NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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9 1 undertaking by the staff across multiple divisions in 2 both NRR and research.              And we anticipate that the 3 endorsement of the ASME high temperature provisions 4 for use by a prospective non-LWR vendors will improve 5 the efficiency and effectiveness at the NRC's review 6 process.
7                  Thank you again for the opportunity to 8 present.        And we look forward to our discussions this 9 morning. Now Jeff Poehler of my staff will provide an 10 overview of the ASME Code Section III, Division 5.
11 Jeff?
12                  MR. POEHLER: Good morning, everyone. Can 13 you hear me well?
14                  MS. LUND:      Yes.
15                  CHAIR RICCARDELLA:            I hear you fine.
16                  (Simultaneous speaking.)
17                  MR. POEHLER:        Yeah, I'll turn my camera 18 off in a minute because I know you guys probably don't 19 want to look at me too much but just so you know who 20 I am. Yeah, so I'm going to be presenting an overview 21 of Section III, Division 5, trying to give a high 22 level overview and just give you a flavor of what it's 23 about.        I find that the Division 5 code is kind of 24 hard to get your hands around.
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10 1 are familiar with codes and standards.                      I've been 2 immersed in it for about a year and a half, and I'm 3 still -- frankly, still learning.                    So I am going to 4 call on project team members if needed for questions, 5 and also we have some experts from the national labs.
6                  Sam  Sham    and    Will      Windes  from    Idaho 7 National Laboratory are in the meeting.                      So I may 8 throw some questions to them.                  But anyway, I would 9 like to also thank the project team for all their help 10 preparing these presentations.
11                  And also this is the first presentation.
12 The second presentation, we'll focus on the review 13 process and potential exceptions and limitations to 14 our review.        So next slide, please.              Okay. So I'm 15 going to discuss the scope of Division 5.
16                  So  the    scope    of      Division    5  governs 17 construction      of    vessels,      piping,      pumps,    valves, 18 supports, core support structures, and nonmetallic 19 core components for use in high temperature reactor 20 systems and their supporting systems.                      And term, 21 construction,        here      includes          material,    design, 22 fabrication, installation, examination, testing, over-23 pressure      protection,        inspection,          stamping,        and 24 certification, so basically the same areas covered by 25 the low temperature construction code in Section III, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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11 1 Division 1.        And high temperature reactors includes a 2 wide variety of designs including gas-cooled reactors, 3 liquid        metal  cooled      reactors,          and  molten      salt 4 reactors.
5                    Division      is    inclusive        of  all    these 6 technologies, meaning it's not specific to any of the 7 particular reactor technologies. Let's go to the next 8 slide, please.        And this slide just kind of shows the 9 spectrum of some of the advanced reactor designs that 10 are being developed by the industry which span from 11 fast reactors to gas reactors, heat pipe reactors.
12                    You have molten salt reactors, and those 13 can be either molten salt cooled and also molten salt 14 fueled.          And you have also -- you have fast and 15 thermal reactors in this spectrum.                      So it's a lot of 16 different types.          Let's go to the next slide.
17                    So Division 5 is a component code, and 18 this is basically high level how it's organized.
19 Class A is the highest safety class.                      The classes --
20 Class A is analogous to Class 1 in Division 1, and 21 Class B is analogous to Class 2 in Division 1.
22                    You also have Class SM for metallic core 23 supports. And then you have Class SN for non-metallic 24 core supports which at this point essential means 25 graphite core support structures.                        And Division 5 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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12 1 recognizes different levels of importance associated 2 with a function of each component as related to the 3 safe operation of the advanced reactor plant.
4                    So these code classes allow a choice of 5 rules        that  provide      a    reasonable        assurance        of 6 structural integrity and quality in line with the 7 relative        importance      assigned        to  the  individual 8 components of the advanced reactor plant. Next slide, 9 please.        So this slide covers some of the things that 10 Division        5  does    not    address,        and  those    include 11 corrosion, irradiation, mass transfer phenomena which 12 would include things erosion and flow accelerated 13 corrosion,          radiation        effects,        other    material 14 instabilities which could be metallurgical phenomena.
15                    It also doesn't cover continued functional 16 performance of deformation sensitive structures such 17 as valves and pumps.            And what that means to me is it 18 doesn't address whether the moving parts actually 19 move.        But let's go to the next slide.              Just a little 20 history now.
21                    So there's a lot of history with the 22 development of the high temperature rules which it's 23 too much to go through in detail with the time we 24 have.        But the design rules do stretch all the way 25 back to the 1960s with Code Case 1331.                        But really NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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13 1 what I want to focus on the 1590 series code cases 2 which were developed in the early '70s.
3                  Those    were      reviewed        by  the  NRC      and 4 endorsed in Regulatory Guide 1.87, Revision 1 which 5 came out in June 1975.            And that endorsed those code 6 cases with conditions.          And then later, the code case 7 series, 1592 through 96, were converted into Code Case 8 N-47, and that later formed the basis for Section III, 9 Division 1, Subsection NH which cover high temperature 10 components.      NRC never reviewed N-47.
11                  And then Division 5 was first published in 12 2011, and it combined Subsection NH and some other 13 high-temperature code cases and also the rules for 14 graphite core components which were completely new.
15 They had never been in a code case before.                            Next 16 slide, please.
17                  So I call this slide the magic decoder 18 ring for the organization of Division 5.                        I'm not 19 going to go through it in detail.                    But I will point 20 that for each subsection on metallic components, there 21 are      subparts  for    low    temperature        and  elevated 22 temperature service.
23                  So Subpart A would be low temperature 24 service.        Subpart B would be elevated temperature 25 service.        And  that      holds      for    Class  A  metallic NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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14 1 components,        Class      B  metallic          pressure  boundary 2 components, and also for core support -- metallic core 3 support.
4                  But the general requirements depart from 5 that pattern with Subpart A being general requirements 6 for      metallic    materials,        Subpart        B being  general 7 requirements for graphite and composite materials.
8 And then when you get to graphite which is Subsection 9 HH, you have Subpart -- or actually Subsection HH is 10 not a metallic core component.                  So Subpart A of that 11 would be graphite material.                Subpart B is composite 12 materials.        Next slide.
13                  So on this slide, I'm going to attempt to 14 explain the temperature boundaries for low and high 15 temperature reactor components under Section III, 16 Division 5. This graph kind of explains the theory of 17 when the high temperature rules are applied.                      So if 18 you look at the table at bottom of the slide, it gives 19 the temperatures.
20                  And those are the temperature boundaries 21 below which you can use the low temperature rules but 22 above which you have to use the elevated temperature 23 rules.        Then the figure at the top here shows the 24 different temperature regimes versus time.                    You see 25 below a certain temperature, that's the temperatures NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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15 1 corresponding to this table.                  The blue region here, 2 you have no creep effects at all.                    So you can use the 3 low temperature rules.
4                    Above that line in the red and yellow 5 regions, you do have creep going on in the yellow 6 region which is at lower times and lower temperatures.
7 You have creep going on but it doesn't affect cyclic 8 life, whereas in the red region at longer times and 9 higher temperatures creep does affect cyclic life. So 10 you have a creep fatigue interaction.
11                    MEMBER BALLINGER:          This is Ron Ballinger.
12 Where is 617 on this table?
13                    MR. POEHLER:          So 617 is addressed by a 14 couple        of code  cases.        So  it's      not actually      in 15 Division 5 itself.          So I would have to look -- I could 16 look up -- I would have to look up the maximum -- the 17 temperature boundary for 617.                      But there is one.
18 There is both a low temperature code case and a high 19 temperature --
20                    (Simultaneous speaking.)
21                    CHAIR RICCARDELLA: Just for information, 22 what does 617 mean?
23                    MEMBER BALLINGER:          It's --
24                    MR. POEHLER:        Go ahead, Ron.
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16 1 ahead.
2                  MR. POEHLER:          Well, it's a nickel-based 3 alloy that has very good high temperature strength, 4 that has been qualified for use in high temperature 5 reactors through a couple of code cases.                  Actually, 6 there's one case for lower temperature use and then 7 one for higher temperature use.                  And --
8                  (Simultaneous speaking.)
9                  MEMBER BALLINGER:            It's not a -- it's a 10 nickel, chrome, iron, cobalt alloy.
11                  MR. POEHLER:        Oh, okay.
12                  MEMBER BALLINGER:          And the code case for 13 that -- the high temperature code case took -- oh, 14 man.      It took a very, very long time to get done.
15                  CHAIR RICCARDELLA: And any idea what that 16 cutoff temperature is, the Tmax is for that alloy?
17                  MEMBER BALLINGER:            It's got to be above 18 800 Fahrenheit for sure.
19                  MR. POEHLER:          We can get that for you.
20 It's --
21                  MEMBER BALLINGER:              Will Windes -- Will 22 would probably know. And so probably Will would know.
23 But I don't see Richard Wright on this list either.
24 He was the guy that was in charge of --
25                  DR. SHAM:      Ron, this is Sam Sham.        So the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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17 1 code      boundary  between      low    temperature    and    high 2 temperature      is  just    like    the      other  or take      the 3 stainless steel that is 800 degree Fahrenheit.
4                  CHAIR RICCARDELLA:            Okay 5                  DR. SHAM: And the maximum use temperature 6 is 1750 degrees Fahrenheit.
7                  CHAIR RICCARDELLA:            Okay.
8                  DR. SHAM:        So it's around 154 degrees 9 Celsius.
10                  CHAIR RICCARDELLA:            Okay. Thank you.
11                  MR. POEHLER:        Thanks, Sam.
12                  MEMBER BROWN:        Pete, can I ask a question 13 on this?      This is Charlie.
14                  CHAIR RICCARDELLA:            Sure. Go ahead.
15                  MEMBER BROWN:          Yeah, Ron popped up and 16 said this new alloy is what, nickel, chromium, iron, 17 cobalt?
18                  CHAIR RICCARDELLA:            Yes.
19                  MEMBER BROWN:          Is there a reason we're 20 reintroducing cobalt into a radiated material such 21 that we -- in my old program, we tried to get cobalt 22 out of everything.
23                  MEMBER BALLINGER:          Yeah, this 617 is not 24 used -- would not be used in a neutron environment.
25                  MEMBER BROWN: Oh, okay. All right. That NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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18 1 wasn't clear to me.            Pardon my question then.              Thank 2 you.
3                  MR. POEHLER:        Okay.
4                  MEMBER BROWN:        That's it.
5                  MR. POEHLER:          All right.          Next slide, 6 please.        Okay.      So  this    slide        talks  about      the 7 materials      that  are    allowed      for      Class  A  metallic 8 materials in Division 5.                There's a limited set of 9 materials.          There's      only    six      materials    and      not 10 included Alloy 617.
11                  But those are Type 304 stainless steel, 12 316 stainless steel, Alloy 800H, 2.25Cr-1Mo, and 9Cr-13 1Mo-V which is commonly known as Grade 91.                      And just 14 a note about the two stainless steels, Division 5 15 specifies the minimum carbon content of 0.04 weight 16 percent for those alloys to give them better high 17 temperature properties.            And they are commonly called 18 Type 304H and Type 316H for that reason.
19                  But  that    designation          is  not  used      in 20 Section III, Division 5.              But you will hear 304H and 21 316H.        And the design parameters for the alloys are 22 mostly in Division 5.                But some of them are also 23 contained in Section II and listed at the bottom of 24 this slide.        Next slide, please.
25                  MEMBER BALLINGER:              This is Ron again.
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19 1 Sam, you said that the limit is -- for 617, the 2 boundary is still 800 Fahrenheit?
3                DR. SHAM:        Yes, going from Division 1 4 rules of the light water reactor.                  The design rules 5 for high temperature is 800 Fahrenheit --
6                MEMBER BALLINGER:          So that just --
7                DR. SHAM:      -- maximum.
8                MEMBER BALLINGER:          -- means the allowable 9 stresses must be higher then, right?
10                DR. SHAM:      The allowable stresses in the 11 creep regime is higher.
12                MEMBER BALLINGER:          Okay.
13                MR. POEHLER:        Okay.      Anymore questions on 14 that slide?    No?    Next slide, please.            Oh, you're on 15 -- no, you're on the right slide.                  Never mind.
16                So this slide kind of breaks down all the 17 different failure modes addressed by Section III, 18 Division 5, and specifically for the Class A materials 19 which is HBB.      So it I didn't say it before, this 20 presentation is going to focus heavily on the Class A 21 metallic materials and also on graphite.
22                We are going to touch on Class B metallic 23 materials and core supports but to a limited extent.
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20 1 about, the failure modes that are covered and also the 2 type of -- that they're considered, what analysis --
3 or what areas of the code prevent those failure codes, 4 where those are located, and the analysis method.                          So 5 the      two    major  types    of    failure        modes  are    load-6 controlled which are just in HBB-3000 and deformation-7 controlled        which    are    addressed          in  non-mandatory 8 appendix HBB-T.
9                    CHAIR RICCARDELLA:              So Jeff, these are 10 analogous        to  what    we    used    to    call    primary      and 11 secondary stresses in Section III, Div. 1?
12                    MR. POEHLER:        Right.      The HPV-3000 rules 13 are going to consider primary stresses.
14                    CHAIR RICCARDELLA:            Okay.
15                    MR. POEHLER: So -- and then what we would 16 consider secondary would be addressed more in the non-17 mandatory appendix HBB-T.
18                    CHAIR RICCARDELLA:              Understand.      Thank 19 you.
20                    MR. POEHLER:          So, load-controlled are 21 those        quantities    evaluated        against      the  allowable 22 stresses        for  primary      loads.          And    those  are      all 23 evaluated using elastic analysis methods.                      Evaluation 24 of deformation-controlled quantities is called out in 25 HBB-3250, and that allows the provisions of non-NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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21 1 mandatory appendix HBB-T to be used.                      But it also 2 allows alternative methods --
3                    CHAIR RICCARDELLA:            I understand.
4                    MR. POEHLER:        -- which is why it's not a 5 non-mandatory appendix.              But these quantities include 6 strains        and    deformations,          ratcheting    and    creep 7 fatigue.          Buckling is also addressed in HBB-T, and 8 that can be either load-controlled, strain-controlled, 9 or a combination of both. And as I mentioned, in HBB-10 3000 rules, only elastic analysis allowed whereas in 11 HBB-T, it allows either elastic analysis, inelastic 12 analysis, and also elastic, perfectly plastic analysis 13 which is allowed through the two code cases.
14                    CHAIR RICCARDELLA:            Yeah.
15                    MR. POEHLER:        So    okay. Next    slide, 16 please.          So this slide attempts to highlight the 17 general characteristics of the HBB primary load design 18 on the left and then the evaluation of design loads 19 versus loads on the right.                So generally, HBB primary 20 load design has the following characteristics.                        It's 21 based        on  elastic    analysis,        load-controlled,        uses 22 stress        classification      and    linearization,    includes 23 design and service level load checks.
24                    It accounts for thermal aging effects with 25 factors on yield and ultimate strength.                        And for NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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22 1 welds, there is a strength reduction factor applied.
2 And then on the right-hand graphic here with respect 3 to design of service loads, so design loads are 4 evaluated in a single temperature, pressure, and set 5 of forces. They're time independent, and they use the 6 allowable stress, S sub 0.
7                  The procedures are very similar to those 8 to the Section III -- I'm sorry, Section I and Section 9 XIII of the ASME Boiler and Pressure Vessel Code. The 10 service loads evaluation accounts for the time history 11 of      loading    and    are    compared          to  time  dependent 12 allowable stresses. And that methodology is unique to 13 Division 5.        But I'm going to talk about that more on 14 some subsequent slides.
15                  CHAIR RICCARDELLA: For the surface loads, 16 do we have different services levels as we did --
17                  MR. POEHLER:          Yes, it addresses Service 18 Level A and B, C and D.
19                  CHAIR RICCARDELLA:            Okay. Thank you.
20                  MR. POEHLER:        Yeah, thanks.        Next slide.
21 Now I'm going to get into the allowable stresses a 22 bit.          So you  have    both    time      dependent  and    time 23 independent level stresses.              S sub 0 is the allowable 24 stress for design loadings.
25                  The  service        level      loading  allowable NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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23 1 stresses include S sub m which is a time independent 2 allowable stress, S sub t which is a time dependent 3 level stress, and then S sub mt, the allowable limit 4 for general primary membrane stress for Surface Level 5 A and B.      And that is determined by the lower of S sub 6 m and S sub t.        And then also you have S sub r, the 7 expected minimum stress-to-rupture.                    That's used in 8 the Level D limits and then also in the deformation-9 controlled analyses of HBB-T. Or I guess I should say 10 used directly in some of those analysis.
11                  CHAIR RICCARDELLA:            So is the S sub 0 --
12 are there values above the cutoff, the 700 and 800 13 degree cutoff temperatures?
14                  MR. POEHLER:        Yes, sir.      And I'm going to 15 discuss that a little more on the next --
16                  CHAIR RICCARDELLA:              Okay. All right.
17 Thank you.
18                  MR. POEHLER:          So    next  slide,  please.
19 Yeah, so the basis for allowable stresses, so both S 20 sub 0 and S sub m are essentially based on Section II, 21 Part D values, either directly or extended using the 22 same methodology for higher temperatures.
23                  CHAIR RICCARDELLA:            Okay.
24                  MR. POEHLER:          And so the S criteria in 25 Section II-D may be controlled by the 100,000 hour NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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24 1 rupture stress or stress to produce a creep rate of 2 0.01 percent in 1,000 hours. So it takes into account 3 creep to some extent.          So I guess what I should've 4 pointed out that S sub 0 is equal to the higher of the 5 S values from Section II-D, Subpart 1, Table 1A, or 6 the 300,000 hour S sub mt value which generally would 7 only be controlling in rare cases.
8                And then the S sub m is basically from 9 Section II-D, Table 2A, the S sub m values in that 10 table at the lower temperatures and then it's extended 11 to higher temperatures using the same criteria in 12 Division 5. And S sub t as I mentioned is the lower 13 of the S sub m or time independent and the S sub t 14 time dependent allowable stress.                  I'm going to talk 15 about how S sub t is determined on the next slide.
16                CHAIR RICCARDELLA:            Okay.
17                MR. POEHLER:        So next slide, please.              So 18 as I said, S sub t is determined by the lowest of 19 three different quantities.            Those are 100 percent of 20 the average stress required to obtain a total elastic 21 primary -- plastic primary and secondary creep strain 22 of 1 percent, or 80 percent of the minimum stress 23 causes initiation of tertiary creep, or 67 percent of 24 the minimum stress to cause rupture or S sub r.
25                And  the    determination            of S  sub    t    is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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25 1 inherently conservation because of the 80 percent and 2 67      percent    factors      applied        to    tertiary    creep 3 initiation and stress-to-rupture.                    Also, it has been 4 noted that of those three criteria, only the 67 5 percent of rupture stress criteria is directly related 6 to component failure. The other two criteria are sort 7 of different, semi-arbitrary points from the creep 8 curves.
9                  CHAIR RICCARDELLA:            Yeah.
10                  MR. POEHLER:        So it is conservative.
11                  (Simultaneous speaking.)
12                  CHAIR RICCARDELLA:              -- have much time 13 until you -- right?            I mean, that's when the curve 14 turns        up and  you    have    not  that      much  time    until 15 rupture, right?
16                  MR. POEHLER:            Right,        yeah.        It's 17 theoretically.          But    some    materials        don't  exhibit 18 classical        creep  behavior.          And      it  also  can      be 19 difficult to determine the onset of tertiary creep in 20 materials      that  don't    have    classic        tertiary    creep 21 behavior.      I'm going to talk about that a little more 22 later.
23                  CHAIR RICCARDELLA:            Okay. Thank you.
24                  MR. POEHLER:        Next slide.        And just a few 25 of the other stresses and material properties, you NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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26 1 have yield strength and ultimate strength which are 2 self-explanatory.          They are extended to the higher 3 temperatures.        You have -- the R factors are weld 4 strength reduction factors to account for the reduced 5 strength of welds compared to the corresponding base 6 metal.
7                  You also have tensile and yield strength 8 reduction factors apply to some materials.                  And those 9 account for thermal aging those materials.                    You also 10 have isochronous stress-strain curves which provide 11 stress versus strain curves for various times up to 12 300,000 hours.          And those curves are derived from 13 creep data.        They're used in the analysis of some of 14 the        deformation-controlled          quantities      and      non-15 mandatory appendix HBB-T.
16                  CHAIR RICCARDELLA:              So 300,000 hours is 17 about 35 years --
18                  MR. POEHLER:        Yeah.
19                  CHAIR RICCARDELLA:              -- for picking that 20 time?
21                  MR. POEHLER: I'm not sure what the reason 22 was.      I might throw that question to Sam Sham.
23                  DR. SHAM:      Oh, yes.          At the time that we 24 sort of look at sort of the design of 40 years, 25 100,000 hours with availabilities of roughly close to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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27 1 that.          And  so  currently,        ASME      is  looking    into 2 extending the allowable stresses to support a longer 3 design lifetime by 60 years.
4                    CHAIR RICCARDELLA:            Okay, okay. So it's 5 basically the 40-year lifetime at some availability 6 level or something.
7                    DR. SHAM:      Yeah, something like that.
8                    CHAIR RICCARDELLA:            I got it. Thank you.
9                    MR. POEHLER:        Thanks.        Okay. Next slide, 10 please.        Okay. So this is talking more about non-11 mandatory appendix HBB-T and trying to break that down 12 a little bit and just discussing the characteristics 13 and also the evaluation methods for some of these 14 deformation-controlled quantities. So you have limits 15 for      strain    accumulation        of  1    percent  average,      2 16 percent linearized bending, or 5 percent maximum.
17 Also, creep and fatigue have to be -- creep and 18 fatigue and buckling have to be evaluated.
19                    And as we mentioned before, these things 20 are typically driven by secondary stresses.                              The 21 right-hand        side    of    this    slide        talks  about      the 22 different analysis methods that are available.                      These 23 include elastic, inelastic, and elastic perfectly-24 plastic analysis.
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28 1 can be applied to all materials. And the rules are in 2 HBB-T, elastic analysis thought to be bounding while 3 inelastic analysis is thought to be more accurate.
4 And inelastic analysis, there are no material models 5 currently in Division 5 for those inelastic analyses.
6                And    then      elastic          perfectly-plastic 7 analysis supplies right now only to a subset of the 8 materials. And those rules are in two code cases.
9 And it's also considered a bounding analysis.                      Next 10 slide, please.
11                Okay. So now I'm going to talk about how 12 creep fatigue is evaluated.                So creep fatigue is 13 assessed based on the interaction diagram which you 14 see on the left there.              A life fraction of creep 15 damage and a usage fraction for fatigue damage are 16 determined separately.
17                The fatigue use is just computed similarly 18 to fatigue for Class 1 components in Division 1, 19 except for Division 5 has its own fatigue curves. And 20 those are in terms of strain versus cycles.                          The 21 coordinates    of  these      two    damaged      fractions      are 22 compared to the interaction diagram, and they have to 23 be inside the lines to pass.
24                Different        materials          have  different 25 allowable creep fatigue envelopes.                  You can see 304 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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29 1 and 316 have an intersection point of 0.3 on the 2 diagram which gives it a little more liberal envelope 3 while 2.25Cr and 800H have an intersection of 0.1, 0.1 4 which is more restrictive.                  And then 9Cr is very 5 restrictive envelope there.
6                  MEMBER BALLINGER:              This is Ron again.
7 Where would 617 -- sorry for keeping to harp on 617.
8 But it's the main high temperature material and it's 9 not on here.
10                  MR. POEHLER:        Yeah.      So this is just an 11 example.        But, yeah, I can't tell you off the top of 12 my head what the interaction diagram looks like.                      But 13 we can --
14                  DR. SHAM:      617 is 0.1, 0.1, Ron.
15                  MR. POEHLER:        0.1, 0.1.      Thanks, Sam.
16                  CHAIR RICCARDELLA:              0.1?  Okay. Thank 17 you.
18                  MR. POEHLER:        Okay.
19                  CHAIR RICCARDELLA: So it'll be the middle 20 of the three curves.
21                  MR. POEHLER: Thanks. And we'll talk more 22 about how creep damage is assessed on the subsequent 23 slides.        Next slide, please.
24                  CHAIR RICCARDELLA:            Well, so the red and 25 blue data points on this slide are a pass versus a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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30 1 fail.        Is that the idea?
2                  MR. POEHLER: Yeah, I think those are just 3 examples.
4                  CHAIR RICCARDELLA:            Yeah.
5                  MR. POEHLER:        I think the blue one would 6 pass for stainless steel, and the orange one would 7 fail.
8                  CHAIR RICCARDELLA:            Yeah, go it.
9                  MR. POEHLER:        Let's go to the next slide.
10 Okay.        So this slide goes into a little more detail 11 about how the creep damage fraction is determined in 12 the creep fatigue assessment.                    So creep damage for 13 different cycle types is based on stresses, and it 14 accounts for stress relaxation.
15                  The upper right figure shows a schematic 16 of a stress relaxation profile.                    And the isochronous 17 stress-strain curves are used to determine the amount 18 of stress relaxation.            The stress rupture curves are 19 used to obtain the rupture time associated with the 20 relaxed stress for the cycle type in question.
21                  The lower right graph shows the stress 22 rupture curves for Alloy 617. And the time to rupture 23 represents the denomination -- denominator and the 24 creep damage term. Welds have a stress rupture factor 25 to account for the reduced rupture strength of welds NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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31 1 compared to the corresponding base metal.                    And that's 2 called out in HBB-T-1715 which requires supplying this 3 to the stress rupture curves when you did a creep 4 damage calculation.
5                  CHAIR    RICCARDELLA:              But  Jeff,      the 6 relaxation        only    occurs      for      deformation    control 7 stresses, right?
8                  MR. POEHLER:          Right.        It's not -- you 9 don't take that into account for primary --
10                  (Simultaneous speaking.)
11                  CHAIR RICCARDELLA:            Right. And -- okay.
12                  MR. POEHLER:        Okay.      Let's go to the next 13 slide.        Okay. Yeah, so a little bit about the 14 buckling rules, there's different buckling limits 15 depending on whether creep is significant or not and 16 also whether the buckling is either strain-controlled 17 or load-controlled.            So load-controlled buckling is 18 characterized by continued application of applied load 19 in the post-buckling regime leading to failure, such 20 as, for example, collapse of a tube under external 21 pressure.
22                  Strain-controlled bucking is characterized 23 by an immediate reduction of strain-induced loading 24 upon initiation of buckling and by the self-limiting 25 nature of the resulting deformations. Even though its NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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32 1 self-limiting,        strain-controlled              buckling  must      be 2 avoided to guard against failure by fatigue, excessive 3 strain, and interaction with load control instability.
4 So figures like the ones shown here provide time-5 temperature        combinations          below        which  the      time 6 independent buckling limits may be used.
7                  And this figure is an example provided for 8 one geometry.        There's figures for several different 9 geometries      in  Division      5.      For      conditions    where 10 strain-controlled and load-controlled buckling may 11 interact or significant elastic follow-up may occur, 12 the load factors for load-controlled buckling are also 13 to be used for strain-controlled buckling.
14                  And the term, elastic follow-up, refers to 15 a    situation    where    only    a    small      portion    of    the 16 structure undergoes inelastic strains while a major 17 portion of the structure behaves in an elastic manner.
18 And in these cases, certain areas may be subjected to 19 strain concentrations due to elastic follow-up of the 20 rest of the connected structure.                      The next slide.
21 Okay.        I'm going to talk a little bit about -- more 22 about the elastic perfectly-plastic or EPP analysis.
23                  So it's a methodology for analysis of 24 deformation-controlled quantities.                    It's implemented 25 via two code cases as I mentioned.                    There's one code NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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33 1 case for strain limits and one code case for creep 2 fatigue.
3                  The staff is reviewing Rev. 0 of the code 4 cases which only cover Type 304 and 316 stainless 5 steel. However, Grade 91 and Alloy 617 are covered by 6 revisions of those code cases.                EPP is intended to be 7 easier to implement than inelastic analysis, but it 8 removes        some of    the    over-conservatism        of  elastic 9 analysis methods.
10                  And some of the advantages include that 11 you don't have to do stress classification.                  You can 12 apply it to any geometry or loading.                  It accounts for 13 redundant load paths, and it's simpler to implement.
14                  It's based on finite element results at 15 integration points.            So there's no linearization of 16 stresses.        And it uses the concept of a pseudo yield 17 stress which is determined by trial and error.
18                  The trial value will be the lower of the 19 yield strength or the stress to cause an -- Stress X 20 to cause inelastic strain in the time interval as 21 determined from the isochronous stress-strain curves 22 in Section III, Division 5.                And that X is the -- so 23 if the component then fails, basically doesn't shake 24 down to elastic action, then you pick a different X, 25 basically. So it's kind of a trial and error process.
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34 1 Okay.        Next slide, please.        Question?        No?
2                  So, now I'm going to give just a little 3 more background on inelastic analysis methods. So the 4 code doesn't provide inelastic material models right 5 now.      So currently this would be left to the designer 6 if he were using the 2017 edition.
7                  Or actually, yeah, the code committees are 8 working on developing these models.                      There is some 9 historical experience from the Clinch River breeder 10 reactor with inelastic analysis of high temperature 11 reactor        components.        And    this      experience    showed 12 inelastic analysis is the least ever conservative of 13 the Division 5 options.
14                  It can be necessary in critical locations 15 where designed inelastic analysis is too conservative 16 to produce a reasonable design.                      And finally, the 17 current status of development of material models for 18 inelastic        analysis      in  the    code      is  that  unified 19 viscoplastic constitutive models for 316H stainless 20 steel and Grade 91 have been developed. And an action 21 to add Grade 91 -- the Grade 91 model to the code has 22 just been balloted.            Next slide, please.
23                  Okay. So moving on to the Class B rules.
24 So the Class B rules for low temperature components 25 are essentially the same as those for Section III, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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35 1 Division 1, Class 2 components.                    For Class B high 2 temperature components, the rules do take creep into 3 account but are simplified compared to the Class A 4 high temperature rules.
5                And there's a lot more materials allowed 6 for Class B high temperature components than for Class 7 A high temperature components. Creep can be neglected 8 for components with non-negligible creep.                There is a 9 Mandatory Appendix HCB-III that defines times and 10 temperatures where creep effects can be neglected.
11 Next slide.
12                A little more about the Class B rules.
13 Basically, they extend the design methodologies of 14 Division 1, Class 2 to higher temperatures. These are 15 designed by rule approach.            They don't use the design 16 lifetime concept.
17                Allowable        stresses            are  based        on 18 extrapolated 100,000 hour creep-rupture properties 19 which is similar to Division 1.                  And fatigue damage 20 from cyclic service is addressed only for piping with 21 creep effects.      A stress range reduction factor is 22 used, similar to Division 1, Class 2, but the factors 23 are reduced to account for elevated temperatures.
24 Next slide.
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36 1 low temperature rules in HGA which are essentially the 2 same as those in Division 1 for core supports.                            And 3 then for elevated temperature metallic core supports, 4 the rules are essentially the same as those for Class 5 B.      I couldn't say Class -- I mean, I meant Class A, 6 Class A elevated temperature components, including the 7 same allowable materials and stresses.                      Next slide.
8                  Okay. Now moving on to construction rules 9 for nonmetallic components.                So Division 5 is unique 10 in that it provides rules for nonmetallic components, 11 including both graphite and composites.                        Graphite 12 materials        are  used    mainly      in    core  components        in 13 certain        advanced      reactor      designs      due  to    their 14 excellent neutron moderation properties.
15                  Rules      for    composites          were  added        in 16 Division 5 for the 2019 edition. In the 2017 edition, 17 the rules for composites were listed as in the course 18 preparation.        So the staff did not review those, the 19 rules for composites.            Next.
20                  CHAIR RICCARDELLA:              What do you mean by 21 composites?        Graphite is one?
22                  MR. POEHLER:          No, I think --
23                  DR. SHAM: They are the C/SiC composite or 24 --
25                  DR. WINDES:        C/SiC and carbon-carbon.
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37 1                    MR. POEHLER:        Silicon carbide maybe.
2                    DR. WINDES:        Yes.
3                    MR. POEHLER:        Yeah.
4                    DR. WINDES: Yeah, silicon carbide matrix, 5 silicon carbide fiber as well as carbon fiber and 6 carbon matrix.          So carbon-carbon and C/SiC.
7                    CHAIR RICCARDELLA:            Okay. Thank you.
8                    MR. POEHLER:          Thank you.      Next slide, 9 please.        So now I'm going to talk about some of the 10 characteristics unique to graphite that provides a 11 little background to help understand the provisions of 12 Division 5 for graphite design and materials. So some 13 of these include the fact that there's no single 14 nuclear grade of graphite. Therefore, we can't design 15 around a specific nuclear grade as we can for metals 16 -- metallic materials.
17                    Graphite is heterogeneous by nature and 18 contains significant pores and cracks.                    Graphite is 19 not ductile. It has brittle or quasi-brittle fracture 20 behavior.        And so the graph here on the right of this 21 slide        shows  an    example      of    turnaround  which        is 22 basically you have a volume change initially with 23 increasing neutron dose where the volume shrinks up to 24 a certain dose and it begins to expand.                      And the 25 material's behavior is completely different before and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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38 1 after the turnaround does is accumulated. Next slide, 2 please.
3                    MEMBER    BROWN:        This      is Charlie    Brown 4 again.        Could you go back to that graphite slide?
5                    MR. POEHLER:        Yeah, let's go back.
6                    MEMBER BROWN:          I'm not a materials guy, 7 just      trying    to  make    sure      I'm    educated  with      the 8 advanced reactor somewhat. Very graphically, describe 9 the negative aspects of graphite in the application of 10 the advanced reactors.            Is that going to result or do 11 you think it would result in a change of their seismic 12 response? Do we have to change seismic rules to allow 13 these things -- these materials to be used?
14                    MR. POEHLER:        That's a good question.            I 15 would probably maybe ask Will Windes if he could talk 16 to that a little bit.
17                    DR. WINDES:      Yeah, I think it -- first of 18 all, I think it depends upon the design.                      So as you 19 can see, you're looking at maybe a 5, 6, 7 percent 20 volumetric change macroscopically at the most for 21 whatever grade of graphite.                  Sometimes you're only 22 looking at something like one -- a half to one percent 23 volumetric change.
24                    So, dependent upon the grade of graphite 25 that you use, the design that you have, then, yeah, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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39 1 you are going to have to maybe consider something like 2 a seismic.        But again, it's going to be very, very 3 specifically design oriented.                Does that --
4                  (Simultaneous speaking.)
5                  MEMBER BROWN:        Go ahead.
6                  MEMBER KIRCHNER:          Charlie, this is Walt.
7 These kind of -- this curve we're looking at here 8 certainly was a big factor in the Fort St. Vrain 9 design which used prismatic graphite blocks.                      And so 10 yes, seismic is one of the issues.                    Bypass is another 11 issue that was a concern.              And subsequent designs of 12 the modular HTGRs that were using prismatic blocks 13 instead        of  pebbles      made    various        design-specific 14 changes.
15                  For example, they put, like, a cap.                    And 16 I'm not describing it very well.                  But instead of just 17 having graphite blocks -- prismatic blocks stacked on 18 each other, they had a little crown that went over --
19 in the advanced designs over the graphite, a block 20 that was below it so that they didn't have wobbling, 21 so to speak, under flow and then having bypass and 22 other kind of issues also and structural stability to 23 deal with things like seismic loadings and such.
24                  CHAIR    RICCARDELLA:              So  that's      the 25 shrinkage concern. So that's in the beginning of this NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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40 1 radiation effect when the volume change is actually 2 shrinkage?
3                    MEMBER KIRCHNER:          Yeah, it's shrinkage, 4 the first feat that they had to deal with.                        I don't 5 know that they were looking at exposures that got back 6 up above the curve where it changed.                      I think in the 7 end reactor, they had those kind of problems, though.
8 That was a production reactor for the weapons program.
9 But they had, I think --
10                    (Simultaneous speaking.)
11                    MEMBER KIRCHNER:          -- entire fluences in 12 that.          And they did cross the curve that you're 13 looking at.
14                    MEMBER PETTI:        So in general, though, for 15 some of these reactors, the design criteria is that 16 you don't design beyond the minimum shrinkage. Others 17 will talk about designing up to the point that you go 18 back to zero.          Nobody talks about designing in the 19 swelling region above zero.
20                    The  other      thing      is    that  the    grade 21 sometimes can be used.              This is in the middle of the 22 core where the fluence is the highest.                      The support 23 structure,        the  fluences        are      much,    much    lower.
24 Sometimes other grades are used.                      It's not all the 25 same grade in the core.                So there's a lot of design NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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41 1 considerations here.            And the HTGR experts are well 2 aware of these things.
3                  MEMBER REMPE:        So Dave, back in the days 4 of General Atomics, they -- help me remember.                    Wasn't 5 it called H-451 or something --
6                  MEMBER PETTI:        Yes.
7                  MEMBER REMPE:        -- is what we had.
8                  MEMBER PETTI:        Yes.
9                  MEMBER REMPE:        And had they -- and I know 10 that source is no longer available.                    Have all these 11 designers      --  because      there's        quite  a  few    folks 12 thinking they're going to do something with a graphite 13 reactor,      for  the    fuel      or    for    the  moderator        or 14 whatever.      And have they identified sources?                  Where 15 are they?
16                  MEMBER PETTI:          Yes, so you see all the 17 data there.      All major grades that are available with 18 all the major vendors have been tested in the DOE 19 program. And these are -- let's call them new grades.
20                  They all -- you could tie them back to the 21 old grades like H-451. There was an equivalent German 22 graphite grade.          And so there's a lineage, if you 23 will.
24                  But there's a lot of grades out there 25 besides the old German and the old H-451 which was the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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42 1 American.        There's Japanese grades now.            China is 2 trying develop their own grades.
3                  MEMBER REMPE:        How do they compare if I 4 look at this --
5                  (Simultaneous speaking.)
6                  MEMBER PETTI:          At least as good as the 7 historic.
8                  MEMBER BALLINGER:          And I think IG 110 is 9 probably better.
10                  MEMBER PETTI:        Well, IG 110, yeah, that's 11 the Japanese grade.            But if you look at the American 12 grade that replaced H-451, it's at least as good, if 13 not better.
14                  (Simultaneous speaking.)
15                  DR. WINDES: I'm sorry. Yeah, I was going 16 to say, so Joy, just to give you an idea.                The PCEA, 17 the blue square, was Graphtec International's attempt 18 to duplicate after 40 years the old H-451 recipe. And 19 we actually had legacy H-451 graphite that we put into 20 their first two capsules of the AGC experiment and did 21 a direct one-for-one comparison between H-451 and 22 PCEA.        And at least from an irradiation response and 23 behavior standpoint, they lay on top of each other so 24 well that you can barely distinguish between H-451 and 25 PCEA.        And that's --
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43 1                    MEMBER REMPE: And is there a huge amount, 2 Will?          I'm sorry to interrupt.              But is the amount 3 large? Do they have a huge source? They're not going 4 to have to do this because they're going to run out 5 again or something?
6                    DR. WINDES:        No. So that's -- and that 7 his one of the questions that's going on right now.
8 And I'm sure that the NRC is going to be involved in 9 that is that the whole issue of source, let's face it.
10 You're not going to be able to duplicate graphite-like 11 metal because you don't take it down to the atomistic 12 composition.
13                    You  take      it    down      to  basically      its 14 molecular airmatic (phonetic) ring structure.                            And 15 that is dependent upon where you get your source 16 material.        So even if you dig the same coal out of the 17 same coal mine or pump it out of the same oil well, 18 the farther down you go in that coal mine or in that 19 well, you're going to have a geologic change to the 20 source material.
21                    But with that said, I mean, everybody 22 knows this.          It's out in the open.                  This is a 23 potential issue and weakness. But with that said, the 24 graphite suppliers are well versed and have a lot of 25 experience in determining and correcting and changing NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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44 1 the formulas so that you get the same response because 2 this      has  been  going      on    since      basically  we    made 3 synthetic graphite for over 100 years.                    People want a 4 consistent material.            And so they have experience to 5 do that.
6                    And that's what the experiment with PCEA 7 was.        It was a completely different source of raw 8 material, completely different facility, absolutely no 9 people that had done H-451 and made it. And yet after 10 40      years    of  laying      dormant,        they  were  able      to 11 resurrect the recipe and show that they could produce 12 a material that had the same characteristics as a 13 material that had been produced 40 years previously, 14 without the same material, without the same source 15 material, or coke source or anything else.
16                    So that's a question that's being debated.
17 I think that most people believe that we can go in and 18 create        a grade    of    graphite        that  is  consistent 19 throughout time.          So if you wanted to have a second, 20 third, or fourth core replace the components, I can 21 tell you that the graphite community is very confident 22 that the suppliers can produce a grade even 20 or 30 23 years later that is consistent with that first core.
24 Does that make sense?
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45 1 Will.        It's good to talk to you again, even if it's 2 virtually.
3                  DR. WINDES:        Yeah, that too.
4                  CHAIR RICCARDELLA:            Walt, this is Pete.
5                  MEMBER KIRCHNER:          This is Walt Kirchner.
6 How well have they done with a Great Lakes carbon 7 supply?        One of the big issues is neutronics and 8 impurities.        So how well are they doing when they 9 replicated        the  H-451?        How    well    did  they    do    on 10 neutronic impurities?
11                  DR. WINDES:        Oh, that's pretty --
12                  MEMBER KIRCHNER:            It's a side question, 13 but it's an important one.
14                  DR. WINDES:          Yeah.        No, that's -- the 15 purification        process      is    actually      probably    a    lot 16 better.        One of the things that -- while the nuclear 17 industry sort of stayed still and dormant in this area 18 and we really haven't pushed the technology, the IT 19 industry has.        And in fact, just as a little anecdote 20 to answer this question indirectly, when we went in 21 and did a quality assurance inspection on one of the 22 graphite suppliers and we told them that this was 23 going to be a nuclear quality assurance inspection and 24 they      were  all    revved      up,    they    called  us      back 25 afterwards and they said, man, that was easy.
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46 1                  If you want to see what specs are and 2 getting the impurity levels down, you got to go 3 through an IT inspection.              So what's happened in the 4 last 20 to 25 years is that the IT, specifically the 5 silicon chip and all of the computer and solar panel 6 folks, they have come in and they have progressed the 7 purification process to the point that we never could 8 have in the past with the nuclear program.                So yeah, 9 it's much better even then than we had in the past.
10                  MEMBER PETTI:        Walt?
11                  MEMBER KIRCHNER:          Thank you. That's good 12 to know.      Okay.
13                  MEMBER PETTI:          Just so you know, these 14 samples that are irradiated, they can be contact 15 handled.
16                  DR. WINDES:        Oh, yeah.
17                  MEMBER PETTI:          They're not very hot at 18 all.
19                  DR. WINDES:        Yeah.
20                  MEMBER PETTI:        That may not have been the 21 case years and years ago.
22                  MEMBER KIRCHNER:          Well, back in the '80s, 23 when Great Lakes Carbon was no longer a source of 24 supply, what I was doing was mining older logs.
25                  MEMBER PETTI:        Yeah.
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47 1                MEMBER KIRCHNER:            But that didn't bode 2 well for the MHTGR program in circa the '80s. So this 3 is encouraging news.
4                DR. WINDES:        Oh, yeah, yeah.        And like I 5 said, it's a lot more -- the purification process is 6 a lot more sophisticated than it ever was for the old 7 327 and the H-451 graphite grades.
8                CHAIR RICCARDELLA: Walt Kirchner, in your 9 initial comments, you distinguished between prismatic 10 core elements versus pebble bed.                    Could you give a 11 little more on why it is that distinction? Is it less 12 critical in a pebble bed reactor?
13                MEMBER KIRCHNER:            Yeah, it's much less 14 critical. Dave could speak to it better than I could.
15 But you don't have such a large structure as you --
16 those prismatic blocks were typically about a meter 17 high, 12 or 14 inches across the flats in a hex 18 configuration. So you've got an actual structure that 19 is in both a thermal and a radiation field that varies 20 both -- in all dimensions. So that creates a lot more 21 challenges for the core designer than dealing with a 22 nice hard pebble.
23                MEMBER PETTI:          But I will say, though, 24 that      the reflector    of    a  pebble      bed  is  quite      a 25 challenge structurally.            There are different issues.
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48 1 It's keyed together.
2                  Think of the -- the prismatic is kind of 3 like Lego blocks with straps around them.                        So it's 4 thermomechanically easier than if you look at the 5 design        of the  reflector        in    a    pebble  bed.        And 6 particularly, even the support, you've got to have --
7 you've got to hold core up and you've got to let the 8 pebbles through.          It's quite the challenge.
9                  DR. WINDES: And I will point out that the 10 image in the lower left-hand corner, that is some of 11 the outer reflector bricks that were designed by the 12 -- for the pebble bed modular reactor, the PBMR in 13 South Africa.          And if you look at that, you can see 14 what Dave's talking about.                They're keyed together, 15 and they have to be interlocked just basically to 16 support those pebbles that are inside there.
17                  And then from a seismic standpoint -- and 18 this is why composites is being considered.                    But from 19 a seismic standpoint, they had silicon carbide or 20 carbon-carbon        belts    that    wrapped      around  the    core 21 purely for seismic considerations. And they basically 22 provided a tensile restraint during seismic events --
23 potential seismic events.
24                  CHAIR RICCARDELLA:                Understand.      Okay.
25 Thank you.
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49 1                  MEMBER BROWN:        Can I ask my question in a 2 different way?        You all buried me in prismatics and 3 everything else.          Let me put this more practically.
4 All the stuff here, it's very brittle.                    I know people 5 have made advances like you all commented on. But I'm 6 thinking about it in a long-term application, for 7 example, conventional reactor fuels as we has today.
8                  We had an earthquake at North Anna.                    And 9 within a short period of time after that, it rode 10 through.        It started back up and had no -- and 11 operated as if nothing ever happened.                    If you have a 12 seismic event of that nature with a graphite-type 13 moderator, is there a concern that you'll be able to 14 go right back to operation?              Or are you going to have 15 to go in and do something in the plant?
16                  MEMBER    PETTI:        There      will  be  a    safe 17 shutdown earthquake, and they will have to design it, 18 right?
19                  MEMBER BROWN:          I'm not worry about safe 20 shutdown,        Dave.      I'm    talking        about  below      safe 21 shutdown.
22                  CHAIR RICCARDELLA: And that would be OBE, 23 an operating basis earthquake.
24                  MEMBER BROWN:        Yeah, and North Anna rode 25 through        that  and    nobody      blinked.        They  kept      on NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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50 1 trucking.      Will graphite be able to do that?
2                  MEMBER PETTI:        It will have to be.
3                  MEMBER BROWN:        How do we prove that?
4                  MEMBER PETTI:        Through the analysis.
5                  CHAIR RICCARDELLA:          That's what this code 6 is all about.
7                  MEMBER BROWN:        Okay.      All right. You've 8 answered      --  we're    not    there      yet    is what    you're 9 fundamentally telling.            There's a lot of work to be 10 done to prove that we'll ride through that similarly.
11 I'm just looking at long-term performance. That's all 12 I'm --
13                  MEMBER PETTI:          Yeah, I mean, Fort St.
14 Vrain had an earthquake they had to survive, as we 15 know, so --
16                  MEMBER BROWN:        Yeah, how long was it in 17 operation?        Or how long it was built before they shut 18 it down?      That's a big difference.
19                  MEMBER BROWN:        How long did it --
20                  (Simultaneous speaking.)
21                  MEMBER BALLINGER: When it was above water 22 or under water?
23                  MEMBER BROWN:        How long did it operate?
24                  MEMBER KIRCHNER:          Well, Charlie, this is 25 Walt. The right answer here is putting Fort St. Vrain NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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51 1 aside which was we can go through all the reasons it 2 was shut down.          But when they -- certainly when they 3 designed it, they designed for a 40-year life.
4                    And if I remember correctly, they had 5 shake        table  tests    for    their      core  and  reflector 6 structure so that they could convince themselves that 7 from      the  stress    and    from      the    mechanical    design 8 standpoint that they configuration would meet both the 9 OBE and SSE requirements.              So I'm confident that they 10 can design a 40-year core, and if it were exposed to 11 an event like in Virginia, if it's below the safe 12 shutdown or OBE limits, I'm confident that they would 13 be able to restart the reactor.
14                    MEMBER BROWN:        Okay.      That's all. That's 15 what I'm --
16                    (Simultaneous speaking.)
17                    MEMBER BROWN: You're an expert. You all 18 --
19                    DR. WINDES:        May I say one thing?
20                    MEMBER BROWN:        Pardon?
21                    DR. WINDES:      May I say one thing, please?
22                    MEMBER BROWN:        Sure, yes, yes.
23                    DR. WINDES:      Yeah.      Just so -- let me ask 24 -- let me answer it in two different ways, sort of a 25 Part 1, Part 2.          First and foremost, from a material NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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52 1 science standpoint, graphite, these components are 2 fairly massive. Putting a crack through those or even 3 chipping an edge off of them so that they may --
4 during a seismic event so that they would not -- the 5 Legos would not fit into each other would be -- from 6 a material science standpoint, would be highly, highly 7 unlikely.
8                    There would have to have been a major flaw 9 near the edge that was undetected. So if the rules --
10 design rules are followed and all of the inspections 11 are followed, there should be no reason for these 12 things        to  --  the    individual        components  to    stay 13 completely and totally stable. The graphite is robust 14 enough to do that.              We're not making this out of 15 glass.        Graphite is a lot more forgiving.            So from a 16 material standpoint, that's not a problem.
17                    The second part is, is that remember that 18 the core is made up of individual stacked components.
19 So they're not rigid.              So if there is a crack that 20 forms in one of these components, the real question 21 is, who cares, because we already have cracks.
22                    We're      stacking        individual    elements 23 together and the gaps between them is significant.
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53 1 problem.
2                Even if a small chip occurs, that's not 3 really a problem. What's really a problem -- and this 4 is why I answered your initial question with, well, it 5 depends upon the design.            The real issue is, can you 6 shut down the reactor in a safe and timely manner?
7 Can you keep the safe -- the fuel safe?            Can you keep 8 the safe operation of the core?
9                And the answer to that is across the 10 Atlantic and that is with the AGR reactors. They have 11 done extensive testing of their core's shake tables, 12 a quarter size, full size reactor cores with a quarter 13 size on gigantic shaped tables. And they have gone in 14 and done up to the maximum expected seismic events 15 that they have in England and found absolutely no 16 problems with their design.
17                And the last thing I will say is that 18 every single brick right now in the UK is cracked, has 19 at least one, if not two through cracks. And yet they 20 can still operate their reactors safely.              And they 21 have done so for 20-plus years.
22                MEMBER REMPE:        But Will --
23                DR. WINDES:        So again -- what?
24                MEMBER REMPE:        -- aren't those cracks why 25 they're shutting down the UK reactors prematurely?
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54 1                    DR. WINDES: No, not really. What they're 2 doing is they're extending the life beyond what the 3 original design life was, which was about 20, 25 4 years.        They're actually extending it beyond.
5                    And as a consequence -- and the real 6 problem is, is that these -- and it all gets back to 7 the design of the actual cores and what you intended.
8 These -- their cores are so keyed and interlocked that 9 they're literally sort of a one shot and they're done.
10 And there's no way you could go in there and pull out 11 a cracked element -- or excuse me, reflector element 12 and pull it out and replace it.
13                    You have to completely disassemble the 14 entire        core. And    so  as    a  consequence  from      the 15 economic standpoint, you can't do that because it's so 16 keyed together.          Cracks don't really matter to them.
17 They've        operated    safely      for  decades  with  cracked 18 components.          But they don't really care because the 19 core is designed to actually withstand that kind of 20 phenomenon.          So again --
21                    MEMBER REMPE:          To say they don't really 22 care, I know that there's been discussions for decades 23 about those cracks.
24                    DR. WINDES:          They care immensely about 25 that. But does it -- is it a critical safety problem?
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55 1 And the answer is no.            They care immensely about it.
2 And there's been hundreds of pounds -- millions of 3 pounds that have been proposed -- or excuse me, been 4 worked on this issue.
5                  So they care immensely about this.                  But 6 what the question that comes down to is, can they 7 operate        their  reactor      cores      safely  with  cracked 8 components?        And the answer is yes, not only in their 9 models, not only in their analysis, but through pure 10 experience.          In the last 20 years, they've had a 11 number of issues and it's never compromised the safe 12 operating envelope of a single one of their reactors, 13 even though everybody knows they are cracked bricks.
14                  So cracked bricks is not necessarily a 15 stopping of the entire reactor consideration.                  So you 16 have to have that knowledge as well when you're 17 designing these cores.              And I apologize.      I've taken 18 up a lot of time in this.
19                  MEMBER BROWN:          No, don't apologize.        I'm 20 not a -- obviously not an expert on graphite, and I 21 know we're going to have a lot discussions later. But 22 this has been an excellent discussion.                  I appreciate 23 your time and the patience --
24                  DR. WINDES:            Oh, no.      Thank you for 25 listening.        I'll talk all day about this.
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56 1                  CHAIR RICCARDELLA: A question on seismic:
2 the UK is not really a high seismic region, is it?
3                  DR. WINDES:        No, it's not.        What they're 4 talking -- I think, if I'm not mistaken, they're 5 taking about something on the order of five, five and 6 a half is what they're really, truly expecting.                        But 7 I believe the original question was something that was 8 not a catastrophic shutdown event but basically a 9 small event that could have a restart.                    The UK is a 10 perfect example for something like that.
11                  CHAIR RICCARDELLA:              An OBE, but there's 12 something that gives metallic structures almost an 13 inherent -- makes them inherently forgiving to seismic 14 loads because most seismic design work is now with 15 linear analysis and you're worried about resonance at 16 certain frequencies.            And as soon as you exceed the 17 yield strength in a metallic component, you get a 18 little bit of yielding that introduces stamping that 19 changes where you are on the resonance curve.                    And so 20 the      loads  go  down    compared      to    what the  elastic 21 analysis would predict.
22                  I'm not sure if that same phenomenon works 23 in graphite -- in a graphite -- on the slide, it has 24 graphite.      It's not ductile.          It's brittle or quasi-25 brittle.      To me, it's almost like masonry structures NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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57 1 don't respond real well to earthquakes compared to 2 steel or wood frame structures.
3                    DR. WINDES:          True, but the design is 4 completely different.            In a metallic, you would have 5 a pressure retaining structure whereas in the graphic, 6 we are not a pressure retaining vessel.
7                    CHAIR RICCARDELLA:            Yeah, yeah.
8                    DR. WINDES:      And so as a consequence, the 9 entire design requirements and the function of the 10 graphite is not to go in and withstand a cracking 11 event.        It's to maintain the structural integrity of 12 the core.
13                    CHAIR RICCARDELLA:            Okay.
14                    MEMBER BALLINGER:          Yeah, this is Ron.        I 15 mean, Section V does not account for -- there's an 16 explicit thing in there.              It says, we don't count for 17 corrosion.        The equivalent for graphite if there's no 18 water in the system is probably wear.                    Am I correct?
19 Erosion?
20                    DR. WINDES: Yeah. Well, wear and erosion 21 is    something      that    we're    considering.      But    quite 22 frankly, it depends on the molten salt or if you have 23 a gas cooled environment.
24                    MEMBER BALLINGER:          Yeah, yeah.
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58 1 and erosion is going to be something.                      For a gas 2 cooled reactor, the only real issue is probably dust 3 entrained high velocity gas in some of these regions.
4 But again, the wear and erosion is probably not 5 something that's really where we're really worried 6 about.
7                  I think really what the main issue is the 8 -- and this is why it's in the design rules itself is 9 the irradiation effects of the graph on the graphite.
10 So unlike metals where it basically sort of bottoms 11 out, the graphite has this sort of dynamic response 12 and behavior.        And it changes, as you can see, as a 13 function of dose.
14                  And that's why turnaround is so critical 15 and      important.      Once    you    figure      out where      your 16 turnaround is, then you can predict and understand 17 what the behavior is going to be like.                    But it's a 18 dynamic response to the irradiation and the radiation 19 temperature.      That's why it's in the design rules and 20 not in Section VIII.
21                  MEMBER    BALLINGER:            Yeah,  I  remember 22 sitting in Arkal Shenoy's office where he had a 23 graphite block that was tested for the Fort St. Vrain 24 reactor.      And that graphite block after exposure to a 25 test loop had about an inch of wear off of one of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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59 1 those blocks.
2                    DR. WINDES:      Right, yeah.      It's both soft 3 and hard.
4                    MEMBER BALLINGER:          Yeah.
5                    DR. WINDES:          My machinist in the back 6 machining samples both loves and hates graphite at the 7 same time.        So yeah, it's beautiful.            It's easy.      It 8 cuts and then it dulls as cutting tools like nothing 9 else, so yeah.
10                    MEMBER KIRCHNER:          Yeah.
11                    DR. WINDES:        Very, very weird.
12                    MEMBER KIRCHNER:          Ron, this is Walt.      The 13 design challenges are quite a bit different than using 14 a metal core.          And the picture in the lower left is 15 illustrative of some of the things you would worry 16 about.        You don't want excessive wear creating dust 17 and contamination in the primary circuit.                  You don't 18 want large bypass because of the volumetric shrinkage 19 there before you get to turnaround.
20                    You have to worry -- probably the biggest 21 seismic worry is not the blocks as Will was saying, 22 cracking and such.          The biggest worry is alignment so 23 that you can ensure that if you're using control rods, 24 you can get the controls rods inserted and achieve a 25 safe shutdown condition.                So it's a different set of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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60 1 -- there are similar issues but a different set of 2 problems that you deal with, especially for the gas 3 cooled --
4                  DR. WINDES:        Yeah, that's where the --
5 that's why I was mentioning where because that changes 6 -- if you have a lot of wear, it might change the 7 seismic response.
8                  CHAIR RICCARDELLA:              Yeah, so this is a 9 very interesting discussion, but I think we have to 10 move on.        We've got about five more slides, I think, 11 in the overview part of the Section III, Division 5.
12 And then I'd like to take a break.                  And then we'll get 13 into        the  staff    --    the    comments        on  the    staff 14 endorsement of Section -- of Division 5.
15                  MR. POEHLER:        Thanks, Pete.        Okay. Yeah, 16 so this -- now moving on, talking about some of the 17 code considerations here with graphite.                      Because all 18 graphite        is  brittle      and    contains        flaws    as      we 19 discussed, core components need to be designed to 20 accept some amount of cracking.                        The upper right 21 figure shows some internal flaws in graphite.
22                  So because of these characteristics, a 23 probabilistic versus deterministic design approach 24 needs to be used because deterministic is generally 25 too limiting for brittle material like graphite.                            So NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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61 1 distribution and possible strengths in the material is 2 needed for a material like this. And a probability of 3 failure in components is based on inherent strength of 4 graphite grades and applied stresses during operation.
5                  So the figure on the left kind of shows 6 distributions of loading on the left-hand curve on 7 that figure and the distribution of material strength 8 on the right-hand curve on that figure.                    The overlap 9 of those two curves represents the reliability of the 10 part.        So let's move on.        Next slide.
11                  MEMBER BALLINGER:              Is there a Weibull 12 modulus spec on this stuff?
13                  DR. WINDES:        Yes.
14                  MR. POEHLER:        I don't know the answer to 15 that.        I would --
16                  DR. WINDES:      Yes, I think there -- that's 17 what you're seeing right here is viable strength 18 curves.        And that's --
19                  MEMBER BALLINGER:              Okay, okay. That's 20 what I thought.
21                  DR. WINDES:        Yeah.
22                  MR. POEHLER:        Okay.      So those slides are 23 talking about the structural integrity assessment 24 methods        that  are      in    Division        5  for  graphite 25 components.        The upper -- or the figure on the right NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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62 1 here shows typical material testing curves used to 2 derive failure probabilities, tensile strength versus 3 failure probability.              So the methods that are in the 4 code for assessment, they're three basic methods, the 5 simplified          assessment        which        is  a  simplified 6 conservative method based on ultimate strength derived 7 from Weibull statistics.
8                    The full assessment is a more detailed 9 assessment          that    takes      into      account  stresses, 10 temperatures, a radiation history, chronic -- and 11 chronic oxidation effects.                    Weibull statistics are 12 used to predict failure probability.                        The maximum 13 allowable probability of failure is determined for 14 three structural reliability classes which related to 15 safety function.
16                    And so those three classes are shown in 17 the table here along with a maximum probability of 18 failure allowed.          And then finally, design by test is 19 also allowed by the code.                    And that involves full 20 scale          testing      to      demonstrate          that    failure 21 probabilities meet the criteria of a full analysis.
22 I'd      like    to  point    out    the    graphite    rules    are    a 23 process.        The designer can't just pick a pre-approved 24 material.          The designer has to demonstrate their 25 specific graphite grade selected will consistently NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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63 1 meet the component requirements.
2                    CHAIR RICCARDELLA:          So this SRC-1, SRC-2, 3 are      they    somehow    analogous      to      Class  A,  Class        B 4 components?
5                    MR. POEHLER:        I believe so.        I think it 6 relates. You would designate that based on the safety 7 significance of --
8                    CHAIR RICCARDELLA:            Yeah, okay.
9                    MR. POEHLER:        -- the consequences for the 10 year of the --
11                    CHAIR RICCARDELLA:              Right. And failure 12 doesn't necessarily mean failure of the structure. It 13 just means cracking?
14                    MR. POEHLER:        Correct, the probability of 15 a through crack.
16                    CHAIR RICCARDELLA:            Okay.
17                    MR. POEHLER:        Okay.      Next slide, please.
18 So yeah, so anyway, this is addressing some of the 19 special        considerations        in    the      design  of  graphic 20 components, and those include oxidation, irradiation 21 and abrasion, erosion which Division 5 says should be 22 addressed.          This figure kind of shows how these 23 special considerations can shift both the loading 24 distribution and the strength distribution in either 25 direction which would change the overlap area for the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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64 1 two distributions.            So degradation can change -- or 2 radiation can increase strength or typically increase 3 the strength.
4                  High temperature can increase strength.
5 Oxidation would decrease strength.                    Molten salt may 6 decrease strength.          Irradiation changes also changes 7 the stress loading on the part.
8                  Dimensional changes can increase stress.
9 But irradiation creep on the other hand can relieve 10 stress.        So the stress distribution curve here on the 11 left could shift either way due to irradiation.                        And 12 those shifts could change this overlap here. So those 13 have to be considered.            Okay.      Next slide, please.
14                  CHAIR RICCARDELLA:          On the previous slide 15 where you were talking about the allowable probability 16 of failure, that really refers to the green curve, 17 right?
18                  DR. WINDES:        Correct.
19                  MR. POEHLER:        Thanks, Will.      Next slide.
20 So this slide is showing the data sheet for graphite 21 which is called out in Article HHA-2-2000 material 22 data sheet forms.          And this data sheet captures most 23 of the graphite degradation issues.                  It includes some 24 material properties or physical properties.
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65 1 dependence, and oxidation effects. Molten salt issues 2 aren't addressed yet in the Division 5 code.                      So the 3 cognizant code test group is currently working on 4 modifications to add that.
5                  And let's go to the next slide.                So this 6 is      the    summary    for    the    overview.        So  just      to 7 summarize, Division 5 was issued as part of the 2011 8 Addenda to the code.            The design rules trace all the 9 way      back    to  the    1960s      for    development      of    high 10 temperature rules for metallics.
11                  Division 5 covers the rules for design, 12 fabrication, inspection, and testing of components in 13 high temperature reactors.                  And these construction 14 rules cover both metallic and nonmetallic components 15 with the rules for nonmetallic components being unique 16 among all design codes worldwide.                      And finally, the 17 ASME code committees are actively pursuing code rules 18 improvement and developing new technologies to support 19 Advanced Nuclear.            With that, I'm going to turn it 20 over to Jordan.
21                  CHAIR RICCARDELLA:            Okay. So well, thank 22 you, Jeff.          That was an excellent summary, and we 23 really appreciate the effort you put into it.                            I'm 24 going to propose now that we take a 15 minute break.
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66 1 Coast time. Okay.
2                (Whereupon, the above-entitled matter went 3 off the record at 10:55 a.m. and resumed at 11:09 4 a.m.)
5                CHAIR    RICCARDELLA:              Okay. We      are 6 approaching -- it is now 11:10, and so we'll -- the 7 meeting will come to order again.
8                And I believe we've had a review of just 9 what's in Section III, Division 5, and now we'll have 10 a    discussion  of    the    NRC    review      and  potential 11 endorsement of it.      And I guess, Jordan Hoellman, are 12 you going to lead this discussion?
13                MR. HOELLMAN: That's right, Pete. I will 14 --
15                CHAIR RICCARDELLA:            Okay.
16                MR. HOELLMAN:        I will start as long as --
17                CHAIR RICCARDELLA:            Thank you.
18                MR. HOELLMAN:        -- everyone is ready.          You 19 guys can all hear me okay, right?
20                CHAIR RICCARDELLA:            Sounds good.
21                MR. HOELLMAN:          All right.      Awesome.        So 22 good morning. My name is Jordan Hoellman.              I am the 23 project manager for the endorsement effort of ASME 24 Section III, Division 5.              I work in the Advanced 25 Reactor Policy Branch in NRR, and I'm excited to be NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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67 1 here to present the staff's endorsement efforts and 2 review philosophy related to the potential endorsement 3 of Division 5.
4                    So, as you know, the NRC staff is taking 5 steps to develop its regulatory infrastructure for 6 advanced non-lightwater reactors to ensure we are 7 prepared        to  support      the    review        of  future    design 8 certifications and other licensing applications.
9                    I want to take just a brief minute to 10 provide some historical context for this effort.                            In 11 2016, we issued the NRC Vision and Strategy for 12 ensuring or achieving non-lightwater reactor mission 13 readiness in response to the increasing interest in 14 advanced reactor designs.
15                    To achieve the goals and objectives in the 16 Vision and Strategy document, the NRC staff developed 17 near-term and long-term implementation action plans or 18 IAPs.        Under IAP 4, the staff intends to enhance the 19 NRC's        technical    readiness        for      potential    advanced 20 non-lightwater          reactor        designs        by  applying      its 21 established        process      for    adapting        its  regulatory 22 framework to ensure that it facilitates the use of 23 codes and standards.
24                    In  2018,      ASME    requested        that  the      NRC 25 review and endorse the 2017 edition of ASME Section NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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68 1 III, Division 5, and the staff responded in August of 2 2018 that we were initiating efforts to endorse with 3 any limitations and exceptions, if necessary, the 2017 4 edition of the code and a new regulatory guide as one 5 way of meeting the NRC's regulatory requirements.
6                    So we can move on to slide 33.
7                    So    the      existence            of    robust      and 8 comprehensive rules for design of high-temperature 9 reactor        systems  and    components          in  the  ASME    code 10 endorsed          by  the      NRC    for    use      by    prospective 11 non-lightwater          reactor      vendors        would    improve      the 12 efficiency        and  effectiveness          of      the  NRC's    review 13 process.
14                    An integral part of the framework will be 15 the      endorsement      of    codes    and      standards    that      are 16 applicable          to  the    construction,          inspection,        and 17 operation of these designs.
18                    In this portion of today's briefing, we 19 will provide an overview of the review process the NRC 20 initiated for the potential endorsement of the 2017 21 edition of Division 5 and discuss some examples of 22 likely        exceptions      and    limitations          to  the    NRC's 23 endorsement.
24                    So let's move to slide 34, please.
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69 1 staff's review will be compiled into two documents 2 that we are currently working to finalize and realize 3 for public comment.              NUREG-2245 will document and 4 provide the technical basis for the endorsement of the 5 2017 edition of the code, as well as code cases N-861 6 and N862, which Jeff described earlier.
7                  NUREG-2245 provides the technical basis 8 for the staff positions in Draft Guide 1380, which is 9 a proposed revision to Reg Guide 1.87, which is titled 10 Guidance for Construction of Class I Components in 11 Elevated Temperature Reactors.
12                  The staff is currently not planning to 13 incorporate this by reference into 10 CFR 50.55(a), as 14 Section III, Division 1, is. One reason we decided to 15 do this is that the staff expects that there will be 16 continued significant revisions to Division 5 between 17 editions.          And  in    NRC    future      reviews  of    those 18 editions,      we  may    take      a  different      approach        to 19 endorsement.
20                  By  endorsing        via      a  reg  guide,      our 21 endorsement, with any limitations and exceptions as 22 discussed in the reg guide, would serve as guidance 23 for a method acceptable to the staff for the use of 24 Division      5. Because      we    are    not  doing this      via 25 rulemaking, an applicant can propose to use Division NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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70 1 5 with different limitations or exceptions, and those 2 reviews will occur in an application-specific basis.
3                  The  Draft      Guide    1380      does  include      an 4 appendix, which establishes acceptable quality group 5 assignments of mechanical systems and components for 6 non-lightwater reactors acceptable to the staff for 7 the      safety  classification        methods,      including      the 8 traditional means outlined in 10 CFR.
9                  Using the definition of "safety-related 10 structures, systems, and components" in -- defined in 11 10 CFR 50.2, it addresses the risk-informed approach 12 outlined in 10 CFR 50.69, and it addresses the method 13 in the Nuclear Energy Institute Document 1804, which 14 is the licensing modernization project methodology, 15 which the NRC endorsed last year in Reg Guide 1.233.
16                  The guidance in Appendix A is intended to 17 provide guidance on selecting an appropriate design 18 standard once the classification methods are used to 19 determine      the  classification          of    each  system      and 20 component.      And I believe there is an ACRS briefing 21 tomorrow that will provide greater detail on the 22 licensing modernization project methodology.
23                  So let's move on to slide 35.
24                  So this slide just communicates the scope 25 of the staff's review of Division 5.                  As I previously NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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71 1 mentioned, Division -- well, yeah.                      Division 5 and 2 code cases and 861 and 862 were included in the 3 staff's        review.          The    staff        did    not    review 4 non-Mandatory Appendix HBB-Y titled Guidelines for 5 Design Data Needs for New Materials.                      And there were 6 few      portions    of  the    2017      edition      that  were      in 7 preparation        at  the    time    the    staff      initiated      our 8 endorsement effort, and we're not endorsing those 9 portions of the code at this time.
10                  The staff initiated a separate effort, as 11 Jeff was describing, to endorse the Alloy 617 code 12 cases that were incorporated -- or that were approved 13 by ASME last year in 2020. The issuance of those code 14 cases represents a significant amount of work over 15 several        years    by    the    Section        III  subgroup        on 16 high-temperature reactors.
17                  The staff is reviewing these code cases 18 separately from the Division 5 endorsement effort 19 included in today's briefing, and we are considering 20 approaches to fold Alloy 617 code cases before we 21 issue the final reg guide endorsing this.
22                  So slide 36.
23                  As Louise was mentioning in her opening 24 remarks, the staff recognized that there was limited 25 expertise outside the ASME code developers on Division NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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72 1 5.      To ensure an independent review, we contracted 2 with national laboratories and commercial contractors 3 for peer review on the technical adequacy of Division 4 5.
5                    We  held    periodic        teleconferences        and 6 shared        a collaborative        SharePoint        site  to    ensure 7 adequate resolution of technical issues raised by the 8 contractors during their independent review.
9                    In addition, we contracted with Argonne 10 National        Lab  and    Idaho      National        Lab  because        we 11 recognized that they had the foremost expertise on 12 this -- on the metallic and graphite portions of the 13 standard.        And those contracts are set up to provide 14 on-call technical expertise to facilitate the staff's 15 review in drafting the NUREG and reg guide.
16                    They    were    also      used      to  answer    staff 17 questions regarding the adequacy and use of Division 18 5, and they were used to provide the staff with the 19 technical basis and historical perspectives related to 20 Division 5.
21                    So slide 37.
22                    So this slide sort of provides an overview 23 of the philosophy we use for endorsement. As Jeff was 24 sort of alluding to, the rules in Division 5 have been 25 developed over the years.                    The NRC endorses ASME NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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73 1 Section        III,  Division      1,    by    incorporating      it      by 2 reference into 10 CFR 50.55(a).
3                    Those    rules      apply      to    components      that 4 operate at temperatures that are typically 700 degrees 5 Fahrenheit or less for carbon or carbon steels and 800 6 degrees Fahrenheit for -- or less for austenitic or 7 high-nickel          alloys      where        creep        effects        are 8 insignificant.
9                    In    the      1970s,        to      facilitate        the 10 construction          of    high-temperature              reactors,      ASME 11 developed        five    code    cases      that      were  intended      to 12 replace or supplement in some cases Section III, 13 Division 1, and those are Code Cases 1592 through 14 1596.
15                    And it was intended that these code cases 16 could be used as a guide with justification provided 17 by    an    applicant    to    supplement        other    Section      III 18 subsections and appendices used to design components 19 operating at high temperatures. They were approved by 20 ASME in the '70s and endorsed by the staff in Reg 21 Guide 1.87 Revision 1.
22                    ASME subsequently incorporated those five 23 code cases into Division 1 with the creation of ASME 24 Section III, Division 1, NH, and the NUREG uses these 25 code cases as a basis for the review of the 2017 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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74 1 edition of Division 5.
2                  MEMBER HALNON: Hey, Jordan. This is Greg 3 Halnon.        Just a quick question.
4                  MR. HOELLMAN:        Sure.
5                  MEMBER HALNON: Since those code cases and 6 the review was done 45 years ago, did you do any 7 cursory look at it or a deeper look to make sure that 8 in today's standards and with the OE that we've 9 received        over  the    last    many      reactor  years    that 10 everything is still good and able to stay with it in 11 this new review?
12                  MR. HOELLMAN:          Yeah.      So we did do a 13 detailed        historical    review      of    the  code  cases,      a 14 comparison        between    the    code    cases    and  what's      in 15 Division 5 now, as well as a look at preliminary 16 safety evaluation reports that the staff developed.
17                  We have also been -- the staff has been 18 involved in all of the working groups and subgroups on 19 the ASME code, and so we've been involved and aware 20 of, you know, the changes that have occurred.                    And so 21 we've looked at any differences and the improvements 22 that have been made over the years to the code.                    So it 23 was a detailed review of what was in the previous code 24 cases as well as the additional information.
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75 1 looked in more detail at what was added or changed 2 versus, you know, what remained the same.
3                MEMBER HALNON:            And so you have high 4 confidence in the review back 45 years ago, is the 5 same that you would expect today moving forward on 6 materials and stuff?
7                MR. HOELLMAN:        Right.        Yeah.
8                MEMBER HALNON:        Okay.
9                MR. HOELLMAN: And the code, you know, has 10 -- as it has been developed over the years, you know, 11 and incorporated into Division 1 in NH, the rules of 12 the code have, you know, incorporated the Division 1 13 standards that we have been endorsing via 10 CFR 14 50.55(a) over the years.
15                MR. HOELLMAN:        Jeff, do you want to add 16 anything there?
17                MR. POEHLER: I just wanted to add that it 18 was within the scope of the contractor reviews to look 19 at      whether  the  code    case      provisions      were    still 20 technically adequate.
21                MEMBER HALNON:        That's what I was looking 22 for, to make sure that there is some -- that it just 23 wasn't --
24                MR. POEHLER:        If that was their basis for 25 recommending something.
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76 1                MEMBER HALNON:        Yeah.
2                MEMBER BALLINGER:          This is Ron Ballinger.
3 I'm      encouraged  to    see    that    617    is going  to      be 4 incorporated into 1380. Was that originally the case?
5                MR. HOELLMAN:        No.      That -- well, we had 6 locations that weren't approved by ASME prior to the 7 initiation      of  our    endorsement          effort,  and    since 8 they've been incorporated and due to interest from, 9 you know, potential applicants, we have decided to 10 take on a separate activity to review those code 11 cases.
12                And because it sort of occurred, you know, 13 as we were getting to the end of our endorsement 14 review of Division 5, we have kind of decided that 15 let's continue with our current effort and take that 16 on in parallel.
17                And then I'll get to it later in the -- in 18 our next steps slide, but the plan currently is to, 19 you know, do the public comment period on our current 20 effort and incorporate it later and do another public 21 comment period, but limit it to the Alloy 617 code 22 cases.
23                MEMBER BALLINGER: So that will delay 1380 24 a little bit, though, right?
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77 1 issuance of it maybe, but we're hoping that we can 2 sort of tackle that in parallel with the public 3 comment period and the final issuance of the reg 4 guide.        But it will overlap a little bit, and that's 5 -- some schedule challenges will have to --
6                    MEMBER BALLINGER:              That's a very good 7 thing.          I think -- we had a previous presentation 8 where we made a comment of why is 617 not included, 9 and the feedback that we got was that it was too early 10 because it had just been approved.                      But now it has 11 changed, and that's a very good thing, in my opinion.
12                    MR. IYENGAR:          This      is  Raj. May      I 13 interrupt here, Jordan?              Raj Iyangar.        I just want to 14 tell you, Ron, we had talked about, discussed this 15 topic.
16                    The code case was the -- 617 was passed, 17 approved late last year.                So by then our Division 5 18 endorsement, the staff endorsement effort, had, you 19 know, been going on for a year and a half.
20                    However, I think based on our discussion 21 we    had,      and based      on    the    feedback      we  got    from 22 industry, we had actually had a conflict with this in 23 a very agile way.          I think Jeff and Jordan will talk 24 about it later.            So that we don't delay the final 25 relief of the current -- the draft guide we are NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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78 1 proposing, but still incorporate the 617, and you know 2 the importance of that because it allows for such high 3 temperatures.
4                    MEMBER BALLINGER:              No, no, that's very 5 good.        Thank you.
6                    MR. HOELLMAN:        Okay.      So I'll continue a 7 little bit in describing how we approached the view.
8 So we compared the articles of ASME, Section III, 9 Division        5,  HBB,    which      is  the      Class A  metallic 10 pressure boundary components operating at elevated 11 temperature service.              So we compared HBB to the 12 related areas of code cases 1592 through 1596 as an 13 approach to validate that the information present in 14 HBB is for high-temperature Class A components, which 15 is analogous to high-temperature Section III, Division 16 1, components addressed by the code cases.
17                    The HBB provisions were reviewed with the 18 assumption that the components have safety-significant 19 functions similar to Division 1, Class 1, components.
20                    In sort of the same manner, we compared 21 the      HCB  rules,    which      is    the      Class  B  metallic 22 components at elevated temperature service, to ASME 23 code NC and HBB since HCB, which is Class B again, is 24 for high-temperature Class B components, analogous to 25 Class 2 components, and NC, but operate at high NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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79 1 temperatures like the components addressed by HBB.
2                So  this    is    where      it  gets  a    little 3 complicated, and Jeff's little magic decoder table 4 comes in handy.
5                So HCB provisions were reviewed with the 6 assumption that the components have similar functions 7 to Division 1, Class 2, components.                    When we get to 8 HGB, which is the core support structures, we compared 9 or the code sort of compares them to HBB, because core 10 support        structures        operate          at    the        same 11 high-temperature range as that established for the 12 Class A components under HBB.
13                When evaluating the provisions of HAA and 14 HAB, which is the general requirements, HAA is for 15 metallic materials and HAB is for graphite materials.
16 We compared these to the 2017 edition of Section III 17 NCA, which the staff endorsed in 50.55(a).
18                When using -- so one of the limitations or 19 exceptions we're proposing is consistent with Section 20 III, Division 1. Where Division 5 references Division 21 1, applicants or licensees should follow any of the 22 applicable      conditions      for      Division      1  that      are 23 identified in 50.55(a).
24                I hope I didn't confuse that too much. So 25 we can move on to the next slide, if that's okay.
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80 1                    So this slide just details the contractor 2 assignments        and    provides      links        to  the  specific 3 contractor reports that were used in combination with 4 the NRC staff's independent technical expertise to 5 develop        the  technical      basis      for      the  findings      in 6 NUREG-2245.
7                    As I mentioned before, the way we assign 8 the -- well, the way that contractor assignments are 9 set up does have some overlap, so we did ensure that 10 we were scheduling coordination meetings between the 11 different contractors and setting up that SharePoint 12 site where we could all collaborate, because some of 13 the rules, for example, in the 3000 reference, the 14 rules in the 2000s portions of the code.
15                    And  so    some      of    the      recommendations 16 provided by the contractors in 3000 relied on some of 17 the findings in -- or the recommendations in 2000 that 18 -- you know, for example, PNNL was not reviewing the 19 2000 portions of the code, and so we needed to make 20 sure that we were all coordinated and could resolve 21 issues between the different contractors.
22                    So we can move on to slide 39, and I'm 23 going to turn it back over to Jeff to walk through 24 some of the expected limitations and exceptions we are 25 proposing throughout our review.
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81 1                    MR. POEHLER: Thanks. Thanks, Jordan. So 2 I'm going to talk a little bit more about the review 3 process for general requirements.                      Jordan touched on 4 that already.
5                    But the process -- basically, the staff 6 compared the 2017 edition of Division 5 HAA and HAB to 7 the 2017 edition of the ASME code, Section III, NCA, 8 to ensure consistency with what the NRC has endorsed 9 in      10    CFR  50.55(a),      or    I  guess      I  should      say 10 incorporated by reference.
11                    Similarly, the staff compared the 2017 12 edition of Division 5, HAA and HAB, to the 2019 13 edition of the ASME code, Division 5, HAA and HAB, to 14 ensure        consistency      with      those        items  that      were 15 corrected in the 2019 edition.
16                    Just a little more background on that, the 17 NRC does participate in the relevant code committees 18 related        to  general      requirements,            and  the    staff 19 recognized that some changes in the 2019 edition of 20 Section III NCA were needed and were not captured in 21 the 2017 edition of HAA and HAB.
22                    The  staff,      therefore,          also  identified 23 exceptions and limitations when there were differences 24 between the 2017 and 2019 editions of Division 5, HAA 25 and HAB.          Even though the rulemaking to IBR are NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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82 1 incorporated by reference, the 2019 edition of HCA 2 into 10 CFR 50.55(a) is not quite final.
3                  So now I'm going to give a couple of 4 examples of exceptions and limitations related to 5 general requirements.            The first one is related to a 6 change in ASME Section III NCA to allow certifying 7 engineers        who    are    not      registered        professional 8 engineers.
9                  The    staff      conditioned        this  in      its 10 rulemaking      to  incorporate        by    reference    the    2017 11 edition of Section III NCA to require the certifying 12 engineers      also    to    be    a  registered        professional 13 engineer.        Therefore, the limitation in the draft 14 guide is for consistency with the condition in 10 CFR 15 50.55(a).
16                  The  second      limitation        is  related        to 17 standards      used  for    accreditation          of  providers        of 18 calibration        and    testing        services.          The      ILAC 19 accreditation process relies on the ISO/IEC 17025 20 standard, and use of the 2005 edition of ISO/IEC 17025 21 was endorsed by the NRC through an SER with several 22 conditions.
23                  In 2017, ISO issued the 2017 edition of 24 ISO/IEC 17025, which the NRC endorsed again through 25 another        SER    with      some      additional        conditions.
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83 1 Therefore,        the  NRC    is    proposing        a  limitation      to 2 Division 5 to make it consistent with the NRC's latest 3 SER.
4                    Next slide, please.
5                    Now I am going to talk about some of the 6 exceptions and limitations that the staff is proposing 7 in the area of mechanical design, and these were 8 identified for several reasons.                        One of those is 9 consistency with Section III, Division 1, conditions 10 in 10 CFR 50.55(a).
11                    An example of that is the condition on 12 socket weld design, and that condition requires a 13 larger leg length on socket welds than Section III, 14 Division 1, allows.
15                    And a second reason would be consistency 16 with Reg Guide 1.87 conditions on Code Case 1592. One 17 example        of  that    is    the    use    of    strain-controlled 18 buckling factors, and this limitation is based on a 19 limitation in Reg Guide 1.87 on Code Case 1592 related 20 to the situation where you could have elastic follow 21 up occurring.
22                    And another reason that we identified 23 condition -- or limitations and exceptions is a lack 24 of guidance in Section III, Division 5.                        And some 25 examples        of  that    are  for    inelastic        analysis      for NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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84 1 meeting the HBB-T deformation limits.
2                  And as I discussed earlier, there are no 3 material models for inelastic analysis currently in 4 the code.        So the staff would want to review any such 5 models that were proposed for use by applicants.
6                  Another      example      is    related    to    stress 7 relaxation cracking, and I am going to talk about that 8 on the next slide.
9                  So let's go to the next slide, please.
10                  So  the    limitation        here    is when      using 11 HBB-T-1710, applicants and licensees should develop 12 their own plans to address the potential for stress 13 relaxation cracking in their designs.                    The basis for 14 this is that stress relaxation cracking is a mechanism 15 causing        enhanced    creep      crack      growth  in    certain 16 materials        caused    by    relaxation        of  weld  residual 17 stresses in components in high-temperature service.
18                  Section III, Division 5, does not contain 19 any provisions addressing stress relaxation cracking.
20 And also, there is a lot of literature on stress 21 relaxation cracking, and there are approaches that can 22 be used to address it that could be used by applicants 23 but they are not in the code.                        So that's why we 24 included a limitation for applicants to, you know, 25 explain how they are addressing this phenomenon.
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85 1                  Next slide?
2                  So this slide discusses the review process 3 for metallic and graphitic materials.                    So unlike in 4 the      area    of  general      requirements        and  mechanical 5 design.        In these areas, the staff did not primarily 6 rely on previous reviews of the code cases.
7                  For metallic materials, the contractor 8 performed independent analysis of materials properties 9 and allowable stresses.                The staff also received 10 additional input by subject matter experts familiar 11 with the development of Section III, Division 5, in 12 the      area  of  materials        properties.          And  we    also 13 considered that an input.
14                  With respect to graphite provisions, they 15 weren't in any previous code cases.                  They were new to 16 Division 5.          Therefore, the staff contracted for 17 technical review of the graphite portions of Division 18 5 by subject matter experts.
19                  I am going to discuss the review of both 20 metallic and graphitic materials in more detail in 21 subsequent slides.
22                  So next slide, please.
23                  So with respect to metallic materials 24 properties, so -- is there a question?                    Sorry.
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86 1 independent      analysis        determined          properties      and 2 allowable stresses with lower values than the code, 3 suggesting that code values are non-conservative. And 4 those were -- contractor reports were primarily by Oak 5 Ridge National Laboratory, which covered allowable 6 stresses in Mandatory Appendix HBB-I-14 and also some 7 other material properties in that appendix.
8                  Oak Ridge performed independent analysis 9 of the metallic materials properties and allowable 10 stresses, and that analysis was based on available 11 data from a literature search, and it used the stated 12 criteria for determining, you know, allowable stresses 13 in Section III, Division 5.
14                  Methodology        used      was    ASME  standard 15 practice as far as that can be defined.
16                  There is a report by Numark that found --
17 that looked at the isochronous stress strain curves 18 and suggested some of those could be non-conservative.
19                  We had Argonne National Laboratory assist 20 with the review of weld strength reduction factors, 21 which were found to not be non-conservative.
22                  So lower values of allowable stresses were 23 typically only at higher temperatures and longer times 24 for the time-dependent properties.                    The NRC staff did 25 consider      these  findings        in    a    holistic  manner, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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87 1 including how these properties are used, inherent 2 conservatisms in the Division 5 design rules, and 3 historical context.          And input from ANL provided 4 historical    context      and    perspective      on  materials 5 properties.
6                Next slide, please?
7                So for metallic materials, limitations are 8 typically in the form of a maximum temperature limit 9 that is more restrictive than allowed by Division 5.
10 These limitations are typically on the time-dependent 11 allowable stresses. The table here shows these limits 12 for the materials where those apply, and you can see 13 that the materials involved here, the properties were 14 typically -- the SMT, which is -- can be controlled by 15 the time-dependent allowable stress, the S sub T, 16 which is the time-dependent allowable stress, and the 17 S sub R, which is the stress to rupture.
18                For non-chrome 1 Moly-Vanadium, we took a 19 different approach. The 2019 Section III, Division 5, 20 properties were endorsed in lieu of the 2017 Section 21 III, Division 5, properties.                    And that was done 22 because ASME updated, in the 2019 edition, the values 23 for non-chrome.        And those compared well with the 24 independent analysis thoughts, while the 2017 values 25 in Division 5 appeared to be somewhat non-conservative NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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88 1 compared to the independent analysis.
2                  Next slide, please.
3                  So I'm going to talk a little more about 4 the basis about how the limitation of one type of 5 allowable stress was determined.                  The example here is 6 Type      304  stainless      steel      where      the  independent 7 analysis suggested significant non-conservatism of the 8 Section III, Division 5, S sub T values for most times 9 and temperatures.
10                  At 300,000 hours, non-conservatism was 11 suggested at temperature -- any temperature greater 12 than 850 degrees F or 450 degrees C, but depending on 13 whether you are in the U.S. customary table or the SI 14 table.
15                  This is based on independent analysis 16 values more than 10 percent lower than the Section 17 III,      Division  5,    values.        Most      of  the  apparent 18 non-conservatism here was driven by the tertiary creep 19 criterion for S sub T.
20                  And the use of the time to tertiary creep 21 as one of the three criteria for time-independent 22 allowable stresses is problematic. There is less data 23 for tertiary creep than for creep rupture in general.
24 It's a smaller database.              It is often difficult to 25 identify the onset of tertiary creep.
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89 1                    And    in      materials          that    demonstrate 2 non-classical creep behavior the onset of tertiary 3 creep can be relatively early, which results in lower 4 times        the  tertiary      creep    and      a    slower  --    lower 5 allowable stresses.
6                    So the ASME code has been deliberating 7 modification or elimination of the tertiary creep 8 criterion.        I mean, they haven't done it yet.
9                    There    is    a    proposal        to  revise      the 10 allowable stress for Type 304 and Type 316 to be made 11 in the ASME code committees, and it will use a linear 12 multiplier on the rupture time to estimate the time of 13 tertiary creep, which will increase the number of 14 tertiary creep data points.
15                    So this issue for Type 304 was mitigated 16 by    ANL    performing      an  alternate          analysis  using        a 17 different approach for tertiary creep data.                      And this 18 analysis showed significant non-conservatism only at 19 temperatures greater than 1,300 -- or greater than or 20 equal to 1,300 degrees Fahrenheit or 700 degrees C.
21                    So next slide, please.
22                    Okay. Now moving on to discussing the 23 review of graphite materials and design, so Numark 24 Associates        provided      a    technical        assessment        of 25 Subsection        HH,  Class    A    Non-Metallic        Core  Support NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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90 1 Structures, Subpart A, Graphite Materials.
2                  The staff completed the review of the 3 above report and all applicable sections of Section 4 III,      Division  5,  and    obtained        clarifications      and 5 feedback from NRC contractors, including Numark and 6 Idaho National Laboratory, in order to come up with 7 the conclusions identified in the NUREG.
8                  The staff's independent review of the code 9 requirements        considered        the      holistic  design        of 10 graphite core support structures.
11                  Next slide, please.
12                  So I am going to talk a little more about 13 some of the exceptions and limitations the staff is 14 proposing for graphite.            So for graphic materials and 15 designs,        several      of    the    limitations      can        be 16 characterized as situations where Division 5 has a 17 numerical      parameter    limit,      but      the staff  is    not 18 convinced the limit is generally applicable to all 19 designs.
20                  And so design-specific justification is 21 requested for the parameter value in these cases as a 22 limitation. And this table shows the provisions where 23 the staff identified such limitations, including the 24 parameter affected in the Division 5 limit, and those 25 include weight loss limit, cohesive life limit, gas NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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91 1 flow velocity, allowed repair depth.                  So that was a 2 common theme for several of the limitations.
3                Next slide?
4                MEMBER KIRCHNER:            Could you -- this is 5 Walt Kirchner.      Can you provide a little more detail 6 on the first one, oxidation?                    That seems like a 7 substantial amount of oxidation weight loss.
8                MR. POEHLER:        It does.      For that I would 9 call on -- if we have either Matthew Gordon or Steve 10 Downey on the line?        Or, if not, I would -- I would 11 ask Will Windes if he can chime in on that, if he is 12 still on.
13                DR. WINDES:        Will is here, but I -- if 14 somebody else from the NRC wants to talk about it 15 first, that would be perfect.
16                MR. POEHLER: Yeah. I mean, Will was not, 17 you know, directly involved with the condition.
18                MEMBER KIRCHNER:          Yeah.      It just strikes 19 me as -- boy, that strikes me as a large oxidation 20 loss.
21                DR. WINDES:        Yeah.
22                MEMBER KIRCHNER:          So way beyond anything 23 a designer would probably want to incorporate in an 24 actual operating envelope.
25                DR. WINDES:        Right.        So here is the --
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92 1 here is the issue.              And you're absolutely correct.
2 This oxidation -- the oxidation limits in the code are 3 being changed rapidly and dramatically as we speak.
4 We have a task group that is working on coming up with 5 something that is much more -- makes much more sense 6 and is much more usable.
7                  There has been a number of papers written 8 in the last year, so that kind of talks about not so 9 much what is the weight loss, but what is the effect 10 of weight loss.
11                  So 30 percent -- and then, of course, the 12 real      issue  --  and    I  think      this    is --  and      I'm 13 speculating now.          I think that one of the main issues 14 that      the  NRC  had    was,    where      is  the weight    loss 15 occurring?
16                  So if it's occurring in the material --
17 excuse me, the structural graphite that is directly 18 surrounding the fuel, this could be extraordinarily 19 significant. If this is something that's occurring --
20 these limits are occurring in something in the core 21 support structures, again, very significant.
22                  If it's occurring in the outer reflector 23 blocks, which are just basically outside of the core 24 area, then it may not be as catastrophic.                            It's 25 obviously going to be beyond what any kind of designer NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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93 1 wants.        And so I think you're absolutely correct.
2 This number is there.
3                  The other number -- I want to call your 4 attention also to number 2, which is something that is 5 in hot debate.          This is what Dave Petti alluded to 6 earlier this morning where this is plus 10 percent 7 over the crossover line for the dimensional change.
8                  And this is something that no -- this is 9 an area that nobody has ever operated their reactors 10 in.        And I think that the NRC is quite correct in 11 identifying this one as a problem as well.
12                  So these are very hot topics that we are 13 changing right now.
14                  MEMBER KIRCHNER:            Yeah. I just can't 15 imagine, with numbers 1 and 2 there, going anywhere 16 near that in an actual design.                  Wow.
17                  CHAIR RICCARDELLA:            No. That's why this 18 table is requesting design-specific justification for 19 these limits, if they use them.
20                  MEMBER KIRCHNER: Yeah. It could be a lot 21 less for certain locations that could be tolerable, 22 and then it --
23                  DR. WINDES:      It could be more for certain 24 locations, because I believe at 30 percent the code 25 says above that you take out -- you just consider the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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94 1 component has no strength basically.                None.
2                MEMBER    KIRCHNER:          Yeah. That's    what 3 you're -- with that amount of oxidation, you probably 4 have no structural rigidity or strength left in the 5 component. Going through that bend in the curve, and 6 then going plus 10 percent on the life limit, my 7 goodness, like I alluded to earlier, in the N reactor, 8 they had issues like that.            And it's just -- it's not 9 practicable for an actual reactor design for a number 10 of reasons, not to get into here.
11                DR. WINDES:      Right.        And I can sum it up.
12 It's too much risk.          You can operate a reactor --
13 obviously, they have -- and reactors are a great 14 example of it.      But, quite frankly, for a civilian 15 reactor, it's just too much risk.                    We don't know 16 what's going to happen above crossover.
17                And there is just so little data, and you 18 just cannot go in and really predict what is going to 19 happen. So, again, these are -- these are things that 20 even before the NRC tagged these as hot button topics 21 we were already working on them, because we ourselves 22 have identified these as real gaps in the code, and 23 significant ones that need to be addressed sooner 24 rather than later for the licensee applicants if they 25 are going to use the code.
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95 1                    MEMBER REMPE:        So what's motivating folks 2 to want to even go to 30 percent?                      Because actually 3 weren't the AGRs -- their limits are actually higher 4 for oxidation. But in the U.S., has that been allowed 5 for things like Fort Saint Vrain?
6                    DR. WINDES: Well, yeah. See, and this is 7 where -- Joy, boy, you always put your finger right on 8 the issues.        Yeah.      The real problem is is that the 9 AGRs      in  the  U.K. have    technically      suffered    much 10 greater weight losses, and they are perfectly safe in 11 operations.
12                    So the -- and then, in the United States, 13 it has been much, much more extremely conservative.
14 You know, nothing more than, say, 10 percent weight 15 loss.        But, of course, they don't tell you where that 16 10 percent weight loss occurs in the code as it exists 17 now, which is, again, an issue we're talking about --
18 or fixing.
19                    So what we tried to do was come up with a 20 happy medium where we said if you go in -- and 21 anything up to 30 percent, you need to justify with 22 your design that this is okay.                      But we're just not 23 even going to consider anything over 30 percent.                          We 24 just can't.
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96 1 designs -- namely, the AGRs -- suffering oxidation 2 beyond 30 percent, without any safety consequences, we 3 just don't want to take that risk on.                  We're going to 4 limit it at 30 percent, and you -- if you get close to 5 30 percent, boy, you'd better have a really good 6 justification for using it.
7                Anything -- and, of course, less and less, 8 you don't have to have as much effort to go in and 9 show that everything is going to be safe.                        So if 10 you're like one or two percent oxidation, then that's 11 not nearly as onerous as, say, 29 or 30 percent.                        Do 12 you understand what I'm saying?
13                MEMBER REMPE:        Yeah.        But I don't think 14 you're understanding my question.
15                DR. WINDES:        Ah. Sorry.
16                MEMBER REMPE:        Why is it proposed to go 17 from 10 percent to 30 percent?              Are there some design 18 developers out there that are saying we think we need 19 to go much higher because our design is going to be 20 approaching 30 percent?
21                DR. WINDES:        No. What we were trying to 22 do -- and, again, please forgive us because we were 23 basically designing in a vacuum.                  There has been no 24 previous designs.      What we were trying to do is make 25 it as universally applicable to as many and all NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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97 1 designs as we could.
2                Just like we don't limit it to one grade 3 of graphite.      If you want to use a different grade 4 than somebody else, you are allowed to do that.                      But 5 you have to do certain things to justify the use of 6 using a graphite or going to those kinds of high 7 oxidation.
8                So it was -- it was basically an attempt 9 to go in and have -- accommodate as many designs as 10 possible.
11                MEMBER REMPE:        Okay.      Thank you.
12                DR. WINDES:        Sure.
13                MEMBER    KIRCHNER:            I  think, too,      the 14 distinction with regard to the AGR is that, if I 15 remember right, these are pressure tube reactors. The 16 graphite is not serving a structural function.                  It is 17 there to be a moderator.
18                So what happens to the graphite in an AGR 19 is not a good example for, say, a pebble bed or a 20 modular HGGR design.            Completely different design 21 construct.
22                MEMBER REMPE:          That's exactly why I was 23 asking is why go so much higher, because I'm not 24 aware, but I don't know of all the designs that are 25 being proposed and what they are thinking of.                    But I NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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98 1 wasn't aware that they would need to go so much 2 higher.
3                    DR. WINDES:        Right.        And, Joy, I haven't 4 -- I mean, I can only think of one design, and it's 5 way out there.          I'm not even sure it is being fully 6 funded at this point.            It's just an idea.        But nobody 7 -- nobody designs I think their reactors for 30 8 percent or more oxidation.                  That would be sort of 9 effectively operating in air with graphite at higher 10 temperatures.        So that's kind of crazy.
11                    And so at that point you're right. I just 12 don't -- I'm not aware of any, but we didn't want to 13 limit.        The code is there to try to be as universally 14 applicable as possible.                  We didn't want to limit 15 anybody.        And because there is -- there are designs 16 out there that can operate at the higher oxidation, we 17 wanted to make sure that they -- we had a higher than, 18 say, just a very conservative five to 10 percent mass 19 loss.        Okay?
20                    CHAIR    RICCARDELLA:              Okay. So    we're 21 reached the published time at -- for the meeting to 22 end.      We've got about four or five more slides.                    I'm 23 going to propose that we continue on and finish.
24 Hopefully we finish in 15 minutes or so.
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99 1 pretty quick, I think, probably famous last words, but 2 -- anyway, so, yeah, this -- so this slide discusses 3 an exception or limitation that doesn't fit the mold 4 of the ones I discussed from the previous slide.
5                    This    has    to    do    with    a  provision        in 6 HHA-3330 that says you have to design to allow for 7 in-service inspection.                But, if necessary, you can 8 replace        in-service        inspection          by  operational 9 monitoring.        And we are not endorsing -- the staff is 10 not      proposing    to    endorse      this      provision  because 11 requirements for in-service inspection are outside of 12 the scope of Section III, Division 5, HHA.
13                    And the provision related to operational 14 monitoring is the one that the staff finds to be out 15 of scope. So that's why we proposed the limitation to 16 not endorse HHA-3330(g).
17                    Let's go to the next slide.
18                    Okay. Shifting gears a little here, so 19 this        slide    just      talks      about      quality      group 20 classifications.          Those are covered in Appendix A of 21 DG-1380, and that provides the staff's guidance on 22 quality group classifications.                    And the approach is 23 very similar to that in NEI-1804.
24                    Quality Group A is safety-related systems, 25 structures, and components.                For that, you can use --
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100 1 use that for components that have safety-related -- or 2 safety-related systems, structures, and components 3 that have safety significance.
4                    Quality Group B is for safety-related 5 systems,        structures,      and    components,      but  Class      B 6 components        in  Division        5  that      have  low    safety 7 significance.
8                    Quality Group C is for non-safety-related 9 systems, structures, and components, with no special 10 treatment, or, I'm sorry, non-safety-related systems, 11 structures, and components with safety significance.
12 And for that you would use ASME Section VIII, Division 13 1 or 2 rules.
14                    And    then      Quality        Group    D  is      for 15 non-safety-related systems, structures, and components 16 with      no    special    treatment,        and      the  owner    would 17 establish standards for use for those.                        And Quality 18 Group D can also be described as systems, structures, 19 and components having low safety significance or no 20 safety        significance.          I    think      it's  no    safety 21 significance.
22                    CHAIR RICCARDELLA: So, Jeff, does Section 23 VIII, Div 1 or 2 have high-temperature considerations 24 in them?
25                    MR. POEHLER:        Section VIII does, yeah.
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101 1                  CHAIR RICCARDELLA:            All right.
2                  MR. POEHLER:        Or pressure vessel.        So --
3                  CHAIR RICCARDELLA: Just another question 4 for -- I'm just curious as to -- for Division 5, why 5 they got away from Class 1 and Class 2 and then call 6 them Class A and Class B?              That's kind of curious to 7 me.      You know, everyone has gotten familiar with the 8 concept of a Class 1 component.
9                  MR. POEHLER:        Yeah.      That sounds like --
10 I would probably call on Sam Sham to chime in on that 11 because I really don't know.              Are you there, Sam?
12                  DR. SHAM: Yes. It was just a distinction 13 that -- when the group puts together Division 5, to 14 distinguish between the rules for the high temperature 15 and the ones in Division 1.
16                  CHAIR RICCARDELLA:            Okay.
17                  MR. POEHLER:        Thanks, Sam.
18                  CHAIR RICCARDELLA:            Thank you.
19                  MR. POEHLER:        Okay.      Next slide, please.
20                  MR. HOELLMAN:        All right.      Jeff, I think 21 this is me again.
22                  MR. POEHLER:        All right.      Thanks, Jordan.
23                  MR. HOELLMAN:        Yep.      So this sort of just 24 summarizes what I talked about earlier, and I'll try 25 to move through it quickly, because I know we're NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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102 1 running out of time.
2                    So we completed our technical review of 3 the      2017    edition,    and    we're      in    the  process        of 4 finalizing          the    documents        for      public    comment.
5 NUREG-2245 provides the technical basis for the staff 6 positions in DG-1380, which is a proposed revision to 7 Reg Guide 1.87.
8                    Jeff just discussed some examples of the 9 exceptions and limitations we expect to include in the 10 draft guide, so I won't spend much more time on that.
11 So let's move to 52, and this just discusses our next 12 steps.        So we're going to finalize the documents for 13 public comment.
14                    We'll address public comments and make any 15 changes necessary in parallel with our effort to 16 review for endorsement the Alloy 617 code cases.                            We 17 will plan to -- our current plan is to supplement the 18 draft guide with the Alloy 617 code cases, and any 19 limitations        or  exceptions        we    think    are  necessary 20 there,        issue  that    for    a  separate        public  comment 21 period, limited to only the Alloy 617 code cases, and 22 then issue the final reg guide, likely in the early 23 2022 timeframe.
24                    CHAIR    RICCARDELLA:              So  when  do      you 25 anticipate that the draft -- the original draft guide NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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103 1 will go out for public comment?
2                MR. HOELLMAN:          Well, we're shooting for 3 the end of this month.
4                CHAIR RICCARDELLA:            Okay.
5                MR. HOELLMAN:          It    does  take  --    I'm 6 realizing that it takes a little bit more time to 7 issue a NUREG than some other documents.                  So there's 8 a little bit of process period there, but we're close.
9 And like I said, the technical review is done.                    It's 10 just, you know, working through the internal reviews, 11 and whatnot, to get the things out the door for public 12 comment.      And it will be a 60-day public comment 13 period.
14                CHAIR RICCARDELLA:            Okay. Okay. Well, I 15 thank the staff for an excellent presentation.                    Very 16 informative.
17                And I want -- at this point, I'll go 18 around, see if any of the members have any additional 19 comments or questions.          I hear silence.
20                MEMBER REMPE:        Pete, this is Joy.
21                CHAIR RICCARDELLA:            Yeah.
22                MEMBER REMPE: Is NUREG-2245 available for 23 public -- to the public, or what's the status of that 24 document?
25                MR. HOELLMAN:        This is Jordan.        Both of NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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104 1 the documents are being finalized internally now.                      So 2 nothing is publicly available yet.                  We are shooting 3 for the end of this month to get things out the door 4 and publicly available.            We wanted to have everything 5 publicly available before this briefing, but we just 6 didn't quite make it.          So apologize for that.
7                  MEMBER REMPE:        But when it is available, 8 please provide a copy to Kent, so he can -- of each 9 document for us, please.
10                  MR. HOELLMAN:        Definitely.      Yep. Thanks, 11 Joy.
12                  CHAIR RICCARDELLA:          Thank you. Any other 13 member comments or questions?                Okay.
14                  So then, at this point, we'll turn to the 15 public and see if there are any public comments.                      Can 16 someone confirm the bridge line is open?
17                  MR. DASHIELL:        The public bridge line is 18 open for comments.
19                  CHAIR RICCARDELLA:            Okay. So if there is 20 anybody from the public out there that would like to 21 make a comment, please state your name and make your 22 comment.      Hearing none -- I'm sorry.            Go ahead.
23                  MS. BOUDART: Could I ask a question? I'm 24 a member of the public.
25                  CHAIR RICCARDELLA:            Yeah. You can make a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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105 1 comment, yeah.
2                    MS. BOUDART: I can make a comment. Okay.
3 Well, I didn't want to make a comment.                I wanted -- I 4 was so fascinated by the discussion of graphite, and 5 of course everybody was.              We really -- the discussion 6 really got kind of stuck there.
7                    I am very interested in the explosion at 8 Chernobyl and the fact that graphite was considered a 9 moderator of the neutron flux there.                  And that when 10 the negative coefficient was reached, I guess that the 11 liquid        moderator    turned      to  bubbles,  so that      the 12 neutron flux was full force on the graphite and it 13 couldn't handle it.
14                    I'm wondering if somebody could -- if 15 there is any comment on the quality of the graphite, 16 because we went -- you went into so much detail about 17 the quality of the graphite and how important that is.
18 Do you -- does anybody think that a different quality 19 of graphite could have prevented that explosion?
20                    MR. MOORE:      This is Scott Moore for the 21 ACRS.        Could the member of the public please state 22 your name for the record.
23                    MS. BOUDART:          Oh, I'm sorry.      I'm Jan 24 Boudart, and I'm a board member of the Nuclear Energy 25 Information Service.
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106 1                MR. MOORE:      Thank you, Ms. Boudart.
2                CHAIR RICCARDELLA:              Does anybody -- we 3 normally don't answer questions, but does anybody wish 4 to make a comment that knows more than I do about what 5 happened at Chernobyl?          I think -- I think --
6                MEMBER REMPE:        Pete, this is Joy.          There 7 is a bit of confusion in the comment that was provided 8 with respect to what this --
9                MS. BOUDART:        Yeah.      I do --
10                MEMBER REMPE:        -- what is the moderator.
11 And, again, we don't respond to public comments at 12 this meeting, but I strongly suggest that the member 13 of the public obtain a general overview article about 14 the Chernobyl reactor design.
15                CHAIR RICCARDELLA:              Yeah. Perhaps you 16 could send that question to Kent Howard, the public 17 official -- the government official for the meeting, 18 and he could maybe coordinate a reply.
19                MS. BOUDART:          Okay.        I appreciate it.
20 Thank you.
21                CHAIR RICCARDELLA:            Any other members of 22 the public?
23                MS. WALKER:        Yeah.      Can you hear me?
24                CHAIR RICCARDELLA:            Yes.
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107 1 of the public. I was wondering if the ASME code cases 2 can be made public. We're not able to access the code 3 cases.
4                CHAIR    RICCARDELLA:              Well,  they      are 5 available for purchase.              The codes generally are 6 available for purchase by ASME. It's an ASME product.
7                MS. WALKER:        Right.        But we thought, you 8 know, it's a standard, so I was just wondering -- so 9 you have to -- you have to pay to know the actual 10 standard.
11                MR. HOELLMAN:        This is Jordan.
12                MS. WALKER: That won't be made available.
13                MR. HOELLMAN:          This is Jordan Hoellman.
14 I think when we release the documents for public 15 comment there are instructions on how you can obtain 16 a copy of the code.        I think the public document room 17 does have a copy for public inspection during public 18 comment periods, but that will all be included in the 19 Federal Register Notice issuing the documents for 20 public comment.
21                MS. WALKER:      I have a -- I'm particularly 22 interested in the code case regarding the inspection 23 of the nuclear pressure vessels for storage.                        And 24 there was a code case that was just published, right, 25 as an approval of an inspection/maintenance program NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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108 1 was      approved    for    the    canisters        at    San    Onofre 2 specifically.
3                  But anyway, I wasn't able to get the 4 current code case.            And I did purchase one, but I 5 don't think it listed the current one.                        So maybe I 6 could email somebody there, just to verify whether 7 what was published that I purchased is the most 8 current.        Would somebody be willing to do that?
9                  CHAIR RICCARDELLA:            Yeah. That --
10                  MS. WALKER:        It's a little bit -- it's a 11 little bit challenging being a member of the public 12 and these code cases being referenced, but we can't 13 access them.
14                  CHAIR RICCARDELLA:              That code case is 15 totally        separate    from    this    meeting,      which    is      on 16 high-temperature code cases.
17                  MS. WALKER:        I understand.
18                  CHAIR RICCARDELLA:            There's probably --
19                  MS. WALKER:      I understand, but it's about 20 --
21                  CHAIR    RICCARDELLA:              You    know,      it's 22 probably more appropriate to contact someone from ASME 23 about whether that's the most current code, not the 24 NRC.
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109 1 getting through to them or getting the information, so 2 -- anyway, thank you.
3                  CHAIR    RICCARDELLA:            Okay. Any    other 4 members of the public that would like to make a 5 comment?
6                  Okay.        With    that,      I  will close      the 7 meeting, and I thank everybody for their participation 8 and all.      And for the members, we'll see you shortly 9 for the meeting on probabilistic fracture mechanics 10 this afternoon.
11                  (Whereupon, the above-entitled matter went 12 off the record at 12:15 p.m.)
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Overview of Section III, Division 5 Advisory Committee for Reactor Safeguards July 20, 2021 Jeff Poehler, Sr. Materials Engineer Reactor Engineering Branch Office of Nuclear Regulatory Research 1
* ASME Section III Division 5 Scope ASME Section III,  - Division 5 rules govern the construction of vessels, Rules for    piping, pumps, valves, supports, core support structures and nonmetallic core components for Construction of      use in high temperature reactor systems and their Nuclear Facility    supporting systems Components -        o Construction, as used here, is an all-inclusive Division 5, High        term that includes material, design, fabrication, installation, examination, testing, overpressure Temperature          protection, inspection, stamping, and Reactors        certification
                  - High temperature reactors include
* Gas-cooled reactors (HTGR, VHTR, GFR)
* Liquid metal reactors (SFR, LFR)
* Molten salt reactors, liquid fuel (MSR) or solid fuel (FHR) 2
 
Examples of Different Advanced Reactor Designs Being Developed By Industry Fast Reactors                          Gas Reactors                      Molten Salt Reactors GE Hitachi        TerraPower, TWR            X-Energy, PRISM                                        Xe-100 Framatome SC-HTGR        Elysium, MCSFR                Terrestrial Energy IMSR Advanced Reactor Concepts, ARC-100                                                                                    ThorCon General Atomic EM2 Ultra Safe Nuclear MMR              Flibe Energy (Gas-cooled Fast Westinghouse, LFR                                          LFTR (thorium)              TerraPower Reactor)
MCFR TerraPower & GEH Oklo, Aurora          Heat Pipe Reactor Natrium Westinghouse eVinci Kairos Power KP-FHR            Moltex Energy, SSR 3
 
Division 5 - A Component Code
* Division 5 is organized by Code Classes:
  - Class A, Class B, Class SM for metallic components -
* Class A is analogous to Class 1 in Section III, Division 1
* Class B is analogous to Class 2 in Section III, Division 1
* Class SM is for metallic core supports
  - Class SN for non-metallic components - e.g. graphite core supports
* Division 5 recognizes the different levels of importance associated with the function of each component as related to the safe operation of the advanced reactor plant
* The Code Classes allow a choice of rules that provide a reasonable assurance of structural integrity and quality commensurate with the relative importance assigned to the individual components of the advanced reactor plant 4
 
Section III, Division 5 Rules for Metallic Components do not address
* Deterioration in service due to
  - Corrosion
  - Mass transfer phenomena
  - Radiation effects
  - Other material instabilities
* Continued functional performance of deformation-sensitive structures such as valves and pumps 5
 
History of Construction Rules for High Temperature Reactor Components
* 159X Code Cases - complete construction rules for elevated temperature pressure boundary metallic components in early 1970s
* Regulatory Guide 1.87 (Rev 1, June 1975) endorsed 159X Code Cases with conditions
* Code Case series 1592-1596 converted to Code Case N-47, which later formed the basis for Section III, Division 1, Subsection NH
* Division 5 first published in 2011, combined NH, other high-temperature code cases, and rules for graphite core components (new).
6
 
Section III Division 5 Organization Class            Subsection      Subpart Subsection ID                      Title          Scope General Requirements Class A, B, & SM                              A        HAA    Metallic Materials              Metallic HA Class SN                                      B        HAB    Graphite and Composite Materials Nonmetallic Class A Metallic Pressure Boundary Components Class A                                        A        HBA    Low Temperature Service          Metallic HB Class A                                        B        HBB    Elevated Temperature Service    Metallic Class B Metallic Pressure Boundary Components Class B                                        A        HCA    Low Temperature Service          Metallic HC Class B                                        B        HCB    Elevated Temperature Service    Metallic Class A and Class B Metallic Supports Class A & B                      HF            A        HFA    Low Temperature Service          Metallic Class SM Metallic Core Support Structures Class SM                                      A        HGA    Low Temperature Service          Metallic HG Class SM                                      B        HGB    Elevated Temperature Service    Metallic Class SN Nonmetallic Core Components Class SN                                      A        HHA    Graphite Materials              Graphite HH Class SN                                      B        HHB    Composite Materials              Composite 7
 
Metal                                                          Maximum Use Temperature                                                        Temperature Creep Affects Cyclic Life Negligible Creep (Creep-fatigue Interaction)
Division 5 Temperature Temperature                  Creep Does Not Affect Cyclic Life Boundaries (Negligible Creep Regime)
Code Temperature for Class A  Division 1 No Creep Effects                                            Boundary (700F ferritic; 800F Components austenitic)
Design Lifetime 8
 
HBB Materials and Design Data
* Limited set of materials:
Minimum carbon content of 0.04
  - Type 304 Stainless Steel*
weight % required for better high
  - Type 316 Stainless Steel*                      temperature properties - Type 304H
  - Alloy 800H                                      and Type 316H - this designation is not used in Section III-5.
  - 2.25Cr-1Mo
  - 9Cr-1Mo-V (Grade 91)
  - Alloy 617 (Code Cases N-872 and N-898)
* Design parameters are mostly self contained in Division 5, except the following contained in Section II:
  - Elastic constants
  - Thermal properties
  - Part of yield strength ( ) table
  - Part of ultimate tensile strength ( ) table 9
 
Failure Modes Addressed by Section III-5 Failure Mode            Type                      Prevented By          Location Analysis Method(s)
Plastic collapse        Load controlled          Primary load design    HBB-3000 Elastic Creep-rupture            Load controlled          Primary load design    HBB-3000 Elastic Creep-fatigue            Deformation controlled    Creep-fatigue rules    HBB-T    Elastic, Inelastic, EPP Gross distortion due to  Deformation controlled    Strain limits          HBB-T    Elastic, Inelastic, EPP incremental collapse and ratcheting Buckling due to short-  Load controlled or strain Buckling limits (time- HBB-T    Elastic, Inelastic term loadings            controlled, or both      independent)
Creep buckling due to    Load controlled or strain Buckling limits (time- HBB-T    Elastic, Inelastic long term loadings      controlled, or both      dependent) 10
 
HBB Primary Load Design
* Based on elastic analysis.
Design Load
* Load-controlled
* Uses stress classification and                    Single temperature,        Time-history of loading pressure, and set of linearization.                                    forces Time-dependent Uses the allowable
* Design and service level load                    Time-independent            stress Uses allowable stress checks.
Unique to Division 5
* Accounts for thermal aging Service Load Very similar to Section I and VIII effects with factors on yield and ultimate strength
* Welds: Strength reduction factor applied 11
 
HBB - Allowable Stresses
* Both time-dependent and time-independent allowable stresses included.
* S0 - Allowable stress for design loadings
* Service Level Loading Allowable stresses
  - Sm - Time independent
  - St - Time dependent
  - Smt - Allowable limit for general primary membrane stress for Service Level A and B
  - Sr - Expected minimum stress-to-rupture. Used for Level D limits and in deformation-controlled analyses (HBB-T) 12
 
HBB - Basis for Allowable Stresses
* S0 - Equal to the higher of S values from Section II-D, Subpart 1, Table 1A, or 300,000 hour Smt
* Sm - From Section II-D, Table 2A, Sm values at lower temperatures, extended to higher temperatures using same criteria
* Smt is the lower of Sm (time-independent) and St (time-dependent) 13
* The lowest of:
(a) 100% of the average stress required to obtain a total (elastic, plastic, primary, and secondary creep) strain of 1%;
HBB - Basis (b) 80% of the minimum stress to cause for St (HBB-      initiation of tertiary creep; and 3221)      (c) 67% of the minimum stress to cause rupture (Sr).
* Determination of St is inherently conservative because of the 80% and 67%
factors applied to tertiary creep initiation and stress-to-rupture.
14
* Sy - yield stress as function of temperature
* Su - ultimate strength Other
* R - Weld strength reduction factors Stresses/Material
* Tensile and yield strength reduction Properties  factors for longtime services (Table HBB-3225-2)
* Isochronous stress-strain curves (ISSCs) 15
 
Deformation Controlled Quantities (HBB-T)
Characteristics                        Evaluation Methods
* A subset of the design limits:              Elastic
* All Class A materials
* Rules found in Nonmandatory Appendix
    - Strain accumulation                    analysis      HBB-T
* Bounding analysis
        - 1% average strain
        - 2% linearized bending
        - 5% maximum strain                  Inelastic
* All Class A materials
* Rules found in NMA HBB-T
    - Creep-fatigue                          analysis
* But no material models in Code (currently)
* Exact analysis
    - Buckling
* Typically are driven by secondary (self limiting) stresses                          Elastic
* Subset of materials (304 and 316 SS, A617, perfectly-    soon to be Grade 91) plastic
* Rules in N-861 and N-862
* Bounding analysis analysis (EPP) 16
 
Creep-fatigue (HBB-T-1411)
* Basically:
: 1. Compute creep damage based on life fraction:
: 2. Compute fatigue damage based on a cyclic life fraction:
Creep damage
: 3. Consult interaction diagram for pass/fail
* Welds: same interaction diagram, factors on damage Fatigue damage 17
 
Creep Damage (HBB-T-1433)
Stress relaxation profile stress
* Construct a stress relaxation curve for each hold in each cycle type time
* Determine creep damage with a time fraction rule for each time interval        Minimum stress-to-rupture for Alloy 617
    =1
* Sum creep damage for all time intervals needed to represent the specified elevated temperature service life  = =1(/
      )
* Database: creep rupture tests
* Welds: use stress rupture factor to reduce the creep rupture strength of the base metal 18
 
Buckling and Instability (HBB-T-1500)
* Limits for both time-independent (creep not significant) and time-dependent (creep-significant) buckling are provided.
* Load factors for both load-controlled and strain-controlled bucking provided.
* Figures provide temperature/time combinations below which the time-independent buckling limits may be used.
* For conditions where stain-controlled and load-controlled buckling may interact, or significant elastic follow-up may occur, the load factors for load-controlled buckling are also to be used for strain-controlled bucking.
19
 
Elastic, Perfectly Plastic (EPP) Analysis
* Use different allowable stresses as pseudo yield stress in EPP finite element analysis to determine different bounding characteristics for different failure modes
* Intended as simplified screening tools in place of elastic analysis methods
* No stress classification
* Any geometry or loading
* Accounts for redundant load paths
* Simpler to implement
      - Based on finite element results at integration points, no linearization
* Current status EPP Design Check          EPP Code Case                Materials Currently Covered Grade 91, Alloy          Primary Load              Under development            All Class A materials 617 covered by Strain Limits            N-861                        304H, 316H, Grade 91, Alloy 617 revision of code cases. Not reviewed by NRC          Creep-fatigue            N-862                        304H, 316H, Grade 91, Alloy 617 20
 
Inelastic Analysis Methods Currently the Code does not      Historical experience on the provide reference inelastic    Clinch River Breeder Reactor Current status models for any of the Class A    Project shows that inelastic materials                        analysis is:
* Specification of the
* The least over-conservative
* Unified viscoplastic material model left to          of the Division 5 options    constitutive models for owners Design
* Necessary in critical        316H stainless steel and Specification or designers      locations where design by    Grade 91 steel have been
* Limits application of the        elastic analysis is too      developed inelastic rules                  conservative to produce a
* Action to add Grade 91 reasonable design            model just balloted.
21
 
Class B Rules HCA - Class B Low Temperature
* Essentially reference III-1, Class 2 rules HCB - Class B High Temperature
* Allows more materials than HBB
* Mandatory Appendix HCB-II contains allowable stress values
* Different allowable stresses for:
* Negligible creep
* Non-negligible creep
* Mandatory Appendix HCB-III defines times and temperatures where creep effects can be neglected.
22
 
Class B Rules Extend rules of Division 1, Class 2 (Subsection NC) to elevated temperature service.
Based on a design-by-rule approach. Design Lifetime concept is not used.
Allowable stresses based on extrapolated 100,000 hour creep-rupture properties.
Fatigue damage from cyclic service is addressed only for piping with creep effects (HCB-3634).
23
 
Core Supports HGA- Low Temperature
* mainly references Section III-1 rules.
HGB - Similar to HBB rules.
* Same materials and allowable stresses.
24
 
Construction Rules For
* Section III Division 5 is the only Nonmetallic    design code that provides construction rules for graphite.
Components (Class SN)
* Graphite materials are used in thermal spectrum advanced reactors because of their excellent neutron moderation properties 25
* There is no single nuclear grade of graphite -
therefore, cant design around a specific nuclear Graphite grade as metals can (i.e., 316H)
* Graphite is heterogeneous by nature, and contains significant pores and cracks.
* Graphite is not ductile - Brittle or quasi-brittle fracture behavior Irradiation significantly alters the graphite behavior - Behavior is completely different before and after turnaround dose is achieved.
26
 
ASME Code Considerations                                                                        50X
* Because all graphite is brittle and contains preexisting flaws,                                                                                  100X
* Core components need to be designed to accept                                                            200X some amount of cracking.
500X
* Probabilistic versus deterministic design approach
* Deterministic is generally too limiting for a brittle material
* A distribution of possible strengths in a material is needed for quasibrittle materials (i.e., flaw size for graphite).
* Probability of failure in component based upon inherent strength of graphite grade and applied stresses during operation.
27
 
Structural Integrity Assessment Methods
* Simplified Assessment (HHA-3220)
: 1. Simplified Analysis Method
                              - Simplified conservative method based on ultimate strength derived from Weibull statistics.
* Full Assessment (HHA-3230)
                              - Weibull statistics for failure probability
                              - Maximum allowable probability of failure defined for three Structural Reliability Classes (SRCs).
Structural Reliability Class                            Maxi. Prob. of Failure SRC-1                                                    1.00E-04 SRC-2                                                    1.00E-02 SRC-3                                                    1.00E-01
* Design by Test (HHA-3240)
                              - Full-scale testing to demonstrate that failure probabilities meet criteria of full analysis. Graphite code is a process.
28
 
Special How toConsiderations apply degradation to POF    in Design of Graphite Core Components
* Oxidation (HHA-3141)
                                                                                        - Loss of strength and geometry changes to be considered
* Irradiation (HHA-3142)
                                                                                        - Property changes to be Irradiation                Degradation                        addressed
* Abrasion and Erosion (HHA-3143)
                                                                                        - To be considered when there is relative motion or high gas flow rate in gas-cooled designs From Dr. Mark Mitchell - PBMR Inc.
Designer should determine the specific changes for their selected graphite grade
 
Graphite Degradation (Form MDS-1 Material Data Sheet)
ASME BPVC Data sheets capture:
* Material properties
                                  - Strength
                                  - Elastic modulus
                                  - CTE
                                  - Conductivity
                                  - Thermal conductivity (Diffusivity)
* Irradiation effects
* Temperature dependence
                                  - Temperature affects everything
* Oxidation effects
 
Summary Division 5 covers the rules Division 5 was issued as  Though the design rules    for the design, fabrication, part of the 2011 Addenda    development for metallic    inspection and testing of to the 2010 Edition of the components traced all the      components for high BPV Code              way to the 1960s          temperature nuclear reactors ASME Code committees are The rules for nonmetallic actively pursuing code rules Construction rules for both components are unique          improvement and metallic and nonmetallic among all design codes          developing new components are provided world-wide            technologies to support Advanced Nuclear 31
 
NRC Review and Potential Endorsement of ASME BPVC, Section III, Division 5 Advisory Committee for Reactor Safeguards July 20, 2021 Jordan Hoellman,                    Jeff Poehler, Project Manager                      Sr. Materials Engineer Advanced Reactor Policy Branch      Reactor Engineering Branch Office of Nuclear Reactor Regulation Office of Nuclear Regulatory Research
 
Purpose Provide an overview of the process for NRCs review and Discuss likely exceptions and potential endorsement of limitations to NRCs 2017 ASME BPVC Section III, endorsement.
Division 5, High Temperature Materials (Section III-5) 33
 
NRC Guidance Documents for Section III-5 Endorsement NUREG-2245 Technical Review of the 2017 Edition      Regulatory Guide (RG) - Acceptability of ASME of ASME Section III, Division 5,        Section III, Division 5, High Temperature Reactors High Temperature Reactors                                  (DG-1380)
* Document the staffs technical evaluation of the
* Describes an approach that is acceptable to the 2017 Edition of Section III, Division 5 and Code  NRC staff to assure the mechanical/structural Cases N-861 and N-862 for acceptability            integrity of components for use in in elevated and endorsement. Provide technical basis for DG-  temperature environments, which are subject to 1380.                                              time-dependent material properties and failure modes.
* Contains exceptions and limitations to the staffs endorsement.
* The regulatory guide will update the guidance of RG 1.87.
* Appendix A of DG-1380 contains staff guidance on quality group classification for high-temperature reactors.
34
 
Scope of Staff Review 1                          2                    3 Section III-5, 2017            Code Cases N-861 Alloy 617 Code Cases Edition                        and N-862
* Separate technical basis
* Did not review                                  document being Nonmandatory Appendix                          developed HBB-Y, so not endorsing.
* Will merge results into final DG-1380 35
 
Contractor Expert Recommendations
* To ensure an independent review of the technical adequacy of Section III, Division 5, NRC used contractors not directly involved with Division 5 code development
* NRC also used contractors more involved with code development on a limited basis to provide historical perspective on Division 5.
36
 
Relied on previous reviews when possible.
                  - Code Cases 1592-1596.
                  - Section III, Division 1.
The NRC staffs review was augmented by Review  input from several national laboratories Process - and commercial contractors.
General See NRCs Advanced Reactor Public Website:
https://www.nrc.gov/reactors/new-reactors/advanced.html#endorev 37
 
Contractor Reports Contractor Topics                                                              ML #
PNNL      Design, Fabrication, Examination, Testing (HBB/HCB/HGB-3000, 4000,  ML20269A145 5000, 6000)
Mechanical design appendixes for metallic core supports (HGB-I, HGB-II, HGB-III, HGB-IV)
ORNL      Materials (HBB/HCB/HGB-2000)                                        ML20269A125 Tables and Figures (Mandatory Appendix HBB-I-14)
Guidelines for Restricted Material Specifications (Non-Mandatory Appendix HBB-U)
NUMARK    Mechanical Design Appendixes for Class A and Class B components      ML20349A003
/EMC2      (HBB-II, HBB-T, HCB-I, HCB-II, HCB-III)
Technical Requirements - Graphite Materials and Design              ML20358A145 Code Cases N-861 and N-862 (all aspects)                            ML20349A002 ANL        Historical Context and Perspective on Materials Properties          ML21090A033 38
 
Review Process - General Requirements Staff compared the 2017 Edition of ASME Code III-5-HAA and -HAB to the 2017 Edition of ASME Code III-NCA to ensure consistency with what the NRC has endorsed in 10 CFR 50.55a.
Similarly, the staff compared the 2017 Edition of ASME Code III-5-HAA and -HAB to the 2019 Edition of ASME Code III-5-HAA and -HAB to ensure consistency with those items that were corrected in the 2019 Edition.
Exceptions or limitations proposed where there are differences.
39
 
Limitation: Staff does not endorse use of a Certifying Engineer who is not also a Registered Professional Engineer.
Basis: Consistency with a similar condition in 10 CFR 50.55a on 2017 Edition of Section III-NCA.
General Requirements  Limitation: When using HAB-3126(b), HAB-3127(b),
        - Examples of  and HAB-3855.3(c)(2) and (d)(2): The procurement Exceptions/Limitations documents should specify that the service will be provided in accordance with the accredited ISO/IEC 17025 program and scope of accreditation.
Basis: This is one of several limitations included for consistency with the updated ILAC accreditation process that is called out in NCA-3126 and also in the 2019 edition of Section III-5.
40
 
Mechanical Design - Exceptions and Limitations
* The staff identified exceptions and limitations related to mechanical design (HBB-3000, HBB-T) for several reasons:
  - Consistency with Section III-1 conditions in 10 CFR 50.55a
* Socket weld design condition.
  - Consistency with RG 1.87 conditions on Code Case 1592 -
* Use of strain-controlled buckling factors.
  - Lack of guidance in Section III-5
* Inelastic analysis for meeting HBB-T deformation limits .
* Stress relaxation cracking.
41
 
Limitation:
When using HBB-T-1710 applicants and Mechanical      licensees should develop their own plans to Design -    address the potential for stress-relaxation Exceptions and    cracking in their designs.
Limitations -
Stress Relaxation Basis:
Cracking    Stress relaxation cracking is a mechanism causing enhanced creep crack growth in certain materials caused by relaxation of weld residual stresses in components in high-temperature service. Section III-5 does not contain any provisions addressing stress-relaxation cracking.
42
 
Review Process -    Class A Metallic materials (HBB-I-14)
Metallic and
* Did not primarily rely on previous reviews.
* Independent analysis of materials properties and allowable stresses by NRC contractor.
Graphitic Materials
* Additional input by subject matter experts familiar with the development of Section III-5.
Graphite (HHA)
* Did not rely on previous reviews.
* Graphite provisions were not in 159X Code Cases - New to Section III-5.
* Technical review of Section III-5 by subject matter experts.
43
 
Metallic Materials In some cases, contractor independent analysis determined properties and allowable stresses with lower values than the code, suggesting code values are nonconservative.
Lower values were typically only at higher temperatures and longer times for time-dependent properties.
NRC staff considered these findings in a holistic manner, including how these properties are used, inherent conservatism of the Division 5 design rules, and historical context.
Input from ANL provided historical context and perspective on materials properties.
44
 
Metallic Materials - Exceptions and Limitations
* For time-dependent allowable stresses, staff placed limitations on endorsement for several materials.
* Limitations in form of maximum temperature limit for several materials.
Material                  Properties                  Temperature Limit Type 304                  Smt , St , Sr                1300 °F, 700 °C Type 316                  Sr                          1300 °F, 700 °C 2-1/4 Cr-1 Mo              Smt , St , Sr                950 °F, 510 °C
* For 9Cr-1Mo-V, 2019 Section III-5 properties are endorsed in lieu of 2017 Section III-5 properties.
45
 
Example of Basis for Conditions on Allowable Stresses For Type 304, ORNL independent analysis suggested significant non-conservatism of Section III-5 St values for most times and temperatures. At 300,000 hours, non-conservatism was suggested at temperatures  850 °F or 450 °C. This is based on independent analysis values more than 10% lower than Section III-5 values.
Most of the apparent non-conservatism driven by the tertiary creep criterion for St .
Tertiary creep criterion for St is a known issue in the Code. It was not intended that this criterion should control most time-dependent allowable stresses.
ANL performed an alternate analysis using a different approach for tertiary creep data. This analysis showed significant non-conservatism only at temperatures  1300 °F or 700 °C.
46
* Numark Associates Inc. provided a technical assessment of Subsection HH, Class A Nonmetallic Core Support Structures, Subpart A, Graphite Materials.
Graphite
* Staff has completed the review of the above Materials and  report and all applicable sections of ASME Section III, Division 5 and obtained clarifications Design    and feedback from NRC contractors (NUMARK and INL) in order to come up with the conclusions identified in the NUREG.
* The staff's independent review of the code requirements considered the holistic design of graphite core support structures.
47
 
Graphite Materials and Design -
Exceptions and Limitations Limitations identified by staff where Division 5 has a numerical parameter limit, but staff not convinced the limit is generically applicable to all designs. Design-specific justification is requested for the parameter value in these case:
Paragraph              Parameter                          Limit in Section III-5 HHA-3141, Oxidation    Weight Loss Limit                  30%
HHA-3142.4, Graphite    Cohesive Life Limit                +10%
Cohesive Life Limit HHA-3143, Abrasion and  Gas Flow Velocity                  100 m/s (mean)
Erosion HHA-4233.5, Repair of  Allowed repair depth                2 mm (0.079 inch)
Defects and Flaws 48
 
Graphite Materials and Design - Other Exceptions and Limitations Limitation: The NRC    Basis: HHA-3330 (g)  Staff is not endorsing  The provision related staff is not endorsing allow for access to  this provision          to operational the provisions of      performing inservice because                monitoring is the one HHA-3330(g).          inspection. If      requirements for        that the staff finds necessary, inservice inservice inspection    out of scope.
inspection may be    are outside of the replaced by          scope of Section III-5, operational          HHA.
monitoring 49
 
Four Quality Groups and associated standards (from DG-1380, Appendix A)
Quality Group A      Quality Group B        Quality Group C    Quality Group D
* Safety-related
* Safety-related
* Non-safety-
* Non-safety-SSCs                  SSCs                  related SSCs with  related SSCs with
* Use ASME
* Use ASME            safety              no special Section III,          Section III,        significance        treatment Division 5 Class      Division 5 Class
* Use ASME
* Owner to A for safety          B for safety          Section VIII,      establish related SSCs          related SSCs          Division 1 or 2    standards for that have            with low safety                            use safety                significance significance
 
Summary The NRC staff has completed its initial review of Section III-5 for potential endorsement.
DG-1380 contains the staffs regulatory position on The NRCs review is documented in NUREG-2245.
Section III-5, including some exceptions and limitations.
Exceptions and limitations were generally identified when the staff found that additional guidance was needed to augment the provisions of Section III-5, or where material properties and allowable stresses are potentially nonconservative.
51
 
Next Steps The NUREG and DG will be issued for public comment.
Alloy 617 Code Cases technical review (in progress).
Make changes as necessary to NUREG and DG to address public comments.
Reissue DG for a second public comment period incorporating Alloy 617 results and resolution of public comments.
Issue draft Alloy 617 technical basis document concurrently with DG.
52}}

Revision as of 20:52, 19 November 2024

Transcript of the Advisory Committee on Reactor Safeguards Future Plant Designs Subcommittee Meeting, July 20, 2021, Pages 1-109
ML21257A324
Person / Time
Issue date: 07/20/2021
From:
Advisory Committee on Reactor Safeguards
To:
Howard, K, ACRS
References
NRC-1595
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