ML19219A174
| ML19219A174 | |
| Person / Time | |
|---|---|
| Issue date: | 08/07/2019 |
| From: | NRC/OCM |
| To: | |
| K. Hamburger 415-2022 | |
| Shared Package | |
| ML19219A167 | List: |
| References | |
| NRC-0431 | |
| Download: ML19219A174 (239) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSIONTitle:High Energy Arcing Fault Comment Resolution and ModelingDocket Number:(n/a)
Location:Rockville, Maryland Date:Wednesday, July 24, 2019Work Order No.:NRC-0431Pages 1-238 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1323 Rhode Island Avenue, N.W.
Washington, D.C. 20005 (202) 234-4433 1 UNITED STATES OF AMERICA 1 NUCLEAR REGULATORY COMMISSION 2+ + + + +3 HIGH ENERGY ARCING FAULT COMMENT RESOLUTION 4 AND MODELING 5+ + + + +6 WEDNESDAY, 7 JULY 24, 2019 8+ + + + +9 ROCKVILLE, MARYLAND 10+ + + + +11 The Commission met in Room T2D30, Two 12 White Flint North, 11555 Rockville Pike, at 9:00 a.m., 13 Mark Thaggard, Deputy Director, Division of Risk 14 Analysis, presiding.
15 16 NRC STAFF PRESENT:
17 MARK THAGGARD, Deputy Director, Division of Risk 18 Assessment 19 MARK HENRY SALLEY, Branch Chief, Fire and External 20 Hazard Analysis Branch, Division of Risk 21 Assessment 22 MICHAEL CHEOK, Office of Research 23 MIKE FRANOVICH, Office of Research 24 RAY FURSTENAU, Office of Research 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 2 KENNETH HAMBURGER, Division of Risk Assessment 1 JS HYSLOP, Office of Research 2 NICHOLAS MELLY, Project Lead 3 GABRIEL TAYLOR, NRC 4 TOM AIRD, NRC 5 MEHDI REISI-FARD, NRC 6 7 ALSO PRESENT:
8 VICTORIA ANDERSON, Nuclear Energy Institute 9 JANA BERGMAN, Curtiss-Wright Corp.
10 PAUL CLEM, Sandia National Laboratories 11 JASON FLOYD, Jensen Hughes 12 GEORGE GELLRICH, Exelon 13 ASHLEY LINDEMAN, Electric Power Research Institute 14 CHRIS LAFLEUR, Sandia National Laboratories 15 DANE LOVELACE, Jensen Hughes 16 DENIS SHUMAKER, Public Service Enterprise Group 17 MARKO RANDELOVIC, Electric Power Research Institute 18 RON REYNOLDS, Exelon 19 ROBERT RISHEL, Duke Energy 20 SCOTT SANDBORN, Sandia National Laboratories 21 KELLI VOELSING, Electric Power Research Institute 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 3 C-O-N-T-E-N-T-S 1 Welcome and Opening Remarks...........4 2 Project Background...............8 3 Comment Resolution...............14 4 Public Questions/Comments............29 5 Working Group Update..............58 6 EPRI Presentation...............104 7 Public Comment................134 8 Overview of HEAF hazard modeling .......136 9 Public Comment................230 10 Closing Remarks................236 11 Adjourn....................238 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.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 4 P R O C E E D I N G S 1 9:01 a.m.2MR. HAMBURGER: Okay. Good morning. It's 39:02. We can get started. Most of you know the drill 4 already, but I'll go through it again for everyone who 5 is new here.
6 Security, please keep your badges on you 7while you're in the building. The only place --
8unfortunately, we didn't get the auditorium. The only 9 place you can go without an escort is across the 10elevator lobby to the bathrooms. Men's are on the 11 left, women's on the right.
12 If you need to go anywhere else, even down 13 out of the building, we need an NRC escort for you.
14So we have plenty of NRC staff in the room. Just grab 15 one of us, and we'll be happy to escort you down.
16 The morning meeting is going to run until 17approximately 12:30. At that point, any available NRC 18 staff will escort everyone down into the lobby.
19 You're welcome to use our NRC cafeteria for lunch, or 20 if you'd like to go off campus, that's fine, too.
21 My phone number is up here on the screen.
22 That's my office number, but it will ring my cell 23phone. So, if you need help getting back in the 24 building, we'll have people shuttling you up here, but 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 5 if you get stuck, feel free to give me a call.
1 We have a slightly revised agenda for this 2 morning, just shuffled some things around and made 3some more time for one of our presentations. But the 4overall day looks about the same. Our morning meeting 5will go till 12:30. And the afternoon meeting will 6 start at 1:30.
7 We are broadcasting the meeting by 8webinar. And we do have people dialed into that. So, 9when you speak, please do so into a microphone. If 10 you're at the table, make sure your table mic is on.
11 If you're in the audience, I would ask that you use 12the standing mic next to the inconveniently placed 13column. If you don't use the mic, the webinar people 14 can't hear you and our court reporter can't get you on 15 the audio feed.
16 Along with that, if you can remember, 17 please try to state your name before you say anything 18 so that the court reporter can record who's speaking 19 and the webinar folks know who's talking.
20 If you have any issues, come grab me at 21the break. And I think our Deputy Division Director, 22 Mark Thaggard, would like to say a few words.
23MR. THAGGARD: Okay, okay. Good morning, 24everyone. As Kenny mentioned, I'm Mark Thaggard. I'm 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 6 the Deputy Director, Division of Risk Analysis, here 1 in the Office of Research.
2 I want to welcome everybody to this 3meeting. You may recall at the last meeting we had on 4 this subject a couple of months ago we promised to try 5 and have more public engagement. So this meeting is 6 part of that effort.
7 As Kenny mentioned, our plan today is to 8have two, actually two separate meetings. The meeting 9this morning is going to focus on two areas. One, 10 we're going to walk through how we have attempted to 11 address the comments that we received.
12I just wanted to note that, you know, 13 while we may agree to disagree on, in terms of whether 14 or not we've appropriately addressed all the comments, 15 I hope that one of the things that come out of this is 16 a clear indication that we put a tremendous amount of 17 effort in terms of trying to resolve the comments.
18 And if we, if there's disagreement in 19 terms of whether we've adequately addressed the 20 comment, hopefully you'll see that we have a strong 21basis for, that we, our proposed resolution, that 22 there's a strong basis for it.
23 The second focus of this morning's meeting 24 is to hear from the working group in terms of give 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 7 them the opportunity to give us a briefing on their 1activities. The working group has put a lot of effort 2into this project. They've put a lot of hours into 3it. And I think that should come out as they go 4 through their presentations this morning.
5 This afternoon is focused on the computer 6 modeling that we're proposing to do in terms of 7 developing the zone of influence. And so, if that's 8 not your area of interest, that's what's going to, the 9focus of this afternoon's meeting. So you're going to 10 be forewarned on that.
11 We've attempted to provide all our 12briefing materials in advance. So hopefully you've 13had an opportunity to look at those. And we can have 14 a lively, engaging discussion.
15 I do ask that people be mindful of the 16 time so that we can hear from everyone, that we can 17give everybody an opportunity to speak. So be mindful 18 of the time.
19 So I just wanted to say those opening 20statements. Again, I appreciate you all coming, those 21 of you who have made it here and those that are just 22 by webinar.
23 Before I turn it over to Mr. Salley, I 24 would like to say that both Mike Cheok and I, we're 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 8going to be here throughout the meeting. So, if 1 there's some question that you need to have with us, 2 we'll be around.
3 So, with that, I turn it over to Mark 4 Salley.5MR. SALLEY: Thanks, Mark. I'm Mark Henry 6Salley. I'm the Branch Chief for the Fire and 7 External Hazards Analysis Branch. I'm just going to 8 take five minutes here and kind of a little background 9 and key this meeting up as we get going.
10First slide, Kenny. And with this 11project, there's a lot of interest. And we understand 12 that. So we've had a lot of public interaction. If 13 we go back to the May 11, 2017 Commission meeting, I 14 believe it was Scot Greenlee from Exelon at the table 15 with the Commission and said that the industry really 16 wanted to work with the NRC on this project. And we 17 took that to heart.
18 We've made as much as transparent and as 19public as possible. Our full scale test plan and our 20 small scale plans were both announced in the Federal 21 Register for public comment.
22 We've had a number of different meetings.
23A very important one was in April 2018. We had a 24public workshop, if you remember. And we had a lot of 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 9 speakers there. We had the NFPA. We had some folks 1from DNVGL. And there's enough information there that 2 we've actually put it in a conference proceeding.
3 It's NUREG/CP-0311.
4 We've also had public meetings this year 5 in January and March and, of course, today's meeting.
6 And again, with the transparency, it's not just the 7public meetings. But we're also making these 8 available for webinars for people who couldn't make it 9 here.10Next slide, please. Just quickly talk 11 about the project and the plan, I think it's important 12 that you understand who some of the players are and 13 what their areas of expertise is.
14 We're working with the National Standards 15 of, National Institute of Standards and Technology for 16a lot of the measurement signs. That's very 17 important. If you're familiar, I mean, they've been 18 doing this for a very long time, you know, to develop, 19 verify, and utilize measurements to quantify the 20 behavior of fire.
21 We can go back as far as 1928 when Simon 22 Enberg (phonetic) here in D.C. did the first full 23scale fire test. It's almost 100 years ago. So we 24 bring that depth of experimental measurement from NIST 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 10in their fire research group. Dr. Tony Putorti, of 1course, is leading that up. Many of you have seen him 2 on the testing.
3 We also have our partners at Sandia 4National Laboratories. A lot of experience comes with 5Sandia, experts in fire measurement. We've got to 6talk to Dr. Chris LaFleur. She's going to be speaking 7 to some of that today.
8 We've also got their experience in 9 electrical measurements, Dr. Paul Clem, who's going to 10 do some presentations on that.
11 One who's not here, but if anybody 12 remembers the past RIC this year, we had Dr. Anthony 13Tanbakuchi, if I said that properly. But he did a 14 fascinating presentation at the RIC on using video as 15 data and how to measure particle transport and to give 16some heat fluxes. And again, we're bringing that 17 technology to the testing program from Sandia.
18Sandia is pretty impressive. And it's 19interesting. They're obviously a Department of Energy 20laboratory. And they do a lot of things outside of 21 our area. But when we tend to reach to them and ask 22 questions, what we find is a lot of the problems that 23 we're facing they've already addressed through a 24 Department of Energy program.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 11So it's just amazing that we can bring 1that level of technology. And Dr. Scott Sandborn here 2runs the program. So he's here if you want any 3 questions.
4 It's also important the laboratory, KEMA, 5 has been a fantastic partner to work with, Frank Cielo 6 at KEMA, and very understanding, very cordial working 7with us. He understands that we're, we have a safety 8mission and that he is very supportive of that. So 9 KEMA has been a great partner to work with.
10 And finally, our electrical contractor, 11it's one thing to be an electrician. But when you 12 start working with medium and high voltage, it's a 13different area altogether. And the folks at BSI have 14 just been fantastic to work with as we put these test 15 programs together.
16 So that's just a quick overview of the 17 players and the project plan and who we've assembled 18 to actually do this work.
19Next slide, please. You know, a second 20 part of it is, okay, so we get the experiments, we do 21 the testing, we get the data, putting it all together 22 and what does it mean to us and how do we use it.
23 Going back to the comment at the 24 Commission meeting, working with industry on this, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 12 obviously we have a memorandum of understanding where 1 we work with EPRI on a number of fire risk and fire 2research programs. And that seemed to be the natural 3 fit here to work with this working group.
4 You know, Lee Iacocca, if you're familiar, 5 I've used this quote before. But Lee Iacocca, he's, 6 of course, the father of the Ford Mustang and saved 7Chrysler from one of their early bankruptcies. But he 8 had a pretty interesting quote on projects.
9 And he said, you know, the things is when 10 you're going to run a project what you want to do is 11 first thing is hire people smarter than you. Second 12 thing is give them clear direction. And the third 13 thing is get out of their way and let them do their 14job. And that's kind of how I'm approaching the 15 working group.
16 We've put some really good people together 17with this group. I mean, EPRI has Tom Short. Anybody 18 who's done any arc flash work is familiar with Tom.
19Ken Fleischer is here. He has a lot of industry 20 experience from his years in Florida. Dane Lovelace 21 from Jensen Hughes is a part of it from EPRI.
22 Shannon Lovvern from my old stomping 23 grounds down at Brown's Ferry, he brings the present 24to the group. Marko and, of course, Ashley, staff 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 13 with EPRI, are also on the panel.
1 On the NRC side, we have our lead, Nick 2 Melly, who you're going to hear from a lot today, is 3the lead on this project. We also have a senior fire 4 protection engineer, Gabe Taylor.
5 Dr. JS Hyslop, who's a member of it, and 6 JS is a very important piece because he takes it back 7 to NUREG/CR-6850 and the original origins of how 8 Appendix M and how this all came to be back in the 9 2000 timeframe.
10 One of our senior electrical engineers is 11 Kenn Miller, who's also a member of the team. Chris 12 LaFleur from Sandia is a member of the group.
13 And we're also bringing on a lot of 14support. Some of our youngest and brightest minds 15 like Kenny Hamburger are supporting the group. And, 16of course, Tom Koshy is bringing a lot of it. So 17 we've got a very solid group of people with a very 18 focused mission.
19 And I think it's important to point out 20the time that these folks have invested in it. We've 21 had two meetings this year. Each one was three days 22face to face working. And folks had to reschedule 23 vacations and reprioritize their work activities and 24just some of them had to fly here. We helped them at 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 14 Jensen Hughes to get together.
1 But those meetings were hugely beneficial.
2 There was a lot of good interaction, a lot of good 3 technical discussion.
4 Also, there's been 21, at least 21 working 5 group meetings where we do webinar and phone meetings.
6And typically, that's every Thursday from 3:00 to 75:00. So this group has a lot of time and a lot of 8 energy invested in this.
9 And I try to listen in to some of them.
10 And I must say that there's some really good technical 11 exchange, some very good discussions about what 12they're doing and the questions they're asking. I 13 think it's going to overall improve the quality of the 14 program.15 One area that we've -- I guess there's 16 been so much activity there that one area we need to 17improve on a little bit more is communication. And 18 Kenny is going to speak to that later today. He and 19 Marko are going to put some discussion on we're going 20 to improve the communications.
21 You know, at the end of the day, I think 22the group is focused. I mean, it's all about safety.
23 At the end of the day, I think they're all focused on 24 that and when working forward.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 15 So that's kind of the primer for today.
1And it's the high level overview. And with that, 2Kenny, I'll turn it over to you. And we can get 3 started.4 MR. HAMBURGER: So I have a presentation 5 here on some of the comment resolution work we've been 6doing. Over the last several public meetings, 7 stakeholders have raised issues with comments that 8 they feel have not been completely or adequately 9 resolved. We've also had some issues that have come 10up since those public meetings. So my goal is to 11 address those and discuss how they are being 12 dispositioned.
13 I actually pulled the transcripts from all 14 of our past public meetings and went through them to 15 pull out those issues that were raised as having not 16been completely or adequately dispositioned. So 17 that's where these issues come from.
18We do have a public meeting, a public 19comment period this morning. So, if there are issues 20that you feel should have made this list and aren't 21 here, I would invite you to raise those issues at that 22 time and we'll be happy to discuss them.
23 A lot of the things that I'm going to talk 24 about here are actually, there's some overlap with the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 16next presentation on the working group. And that's 1 because many of these issues have been dispositioned 2through the efforts of the working group. So Nick and 3 Marko are going to cover some of these issues in more 4 detail when they get to their presentation.
5 One of the comments we've received is 6 regarding our 8-second test that's in our current test 7 plan. The comments were that the 8-second tests are 8 not realistic and don't reflect operating experience 9 and don't reflect plant configuration.
10 So, as part of the working group's 11 efforts, they have reviewed all of the HEAF events 12 from the US operating experience. And Nick is going 13to talk about the specifics of those OpE events. But 14 we do see 8-second or longer HEAF events in both 15 medium and low voltage equipment.
16 But more importantly, and I think this 17gets really to the heart of the concern that was 18 raised by the stakeholders, is that our goal is not to 19 take the results of an 8-second test and just apply it 20 generically in a bounding manner to any enclosure in 21 the plant.
22 That's the one-size model, the one-size-23fits-all model that we have now. And that's 24specifically what we're trying to enhance. We're 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 17trying to increase the realism. We're trying to 1increase the resolution of that model. And again, 2 Nick and Marko are going to go into detail on this.
3 But I want to call out Kenneth Fleischer, 4 who did some excellent work. He did a comprehensive 5 review of all plants' one line electrical distribution 6 diagrams and has basically broken it up into zones.
7 And the working group has created an event 8 tree that will, takes into account where the component 9 is in the electrical distribution system, what 10 protective equipment is available at that point in the 11 electrical distribution system, and is the basis for 12developing a maximum credible fault duration. And 13 that's going to be one of the bases for the hazard 14 model that the working group is going to develop.
15 So, again, we're not taking the most 16 conservative, the longest duration tests and just 17applying it across the board. This, the results of 18 these tests are going to be applied where they're 19 applicable and where they're appropriate.
20And if I say anything incorrect or in 21 insufficient detail, Nick and Marko, you should feel 22 free to jump in.
23This slide might look familiar. This was 24presented at our last public meeting. The comment we 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 18 received was that our arcing location, which pull up 1 the pointer here --
2MR. MELLY: Yeah, and one additional piece 3of information is we are kind of discussing some of 4 these at a very high level right now. We will be 5 discussing them in greater detail as we get forward 6 through today.
7 The working group has taken a look at a 8 lot of these comments and the resolution and tried to 9 come up with a very comprehensive way of dealing with 10them. So we'll be discussing a lot of these issues as 11 we move forward today.
12 So, if there are any lingering questions 13 after Kenny's comment resolution, feel free to ask 14 right now, however, do acknowledge that a lot of this 15 will be discussed in greater detail as we move 16 forward.17MR. HAMBURGER: So, in our first set of 18 tests as part of our phase two testing, we initiated 19 the arcs in the highlighted location where it says 20primary cable connections. This was done in 21 accordance with the IEEE guide for medium voltage arc 22 fault testing at the further point away from the power 23 supply across all three phases.
24 The comment that we received was that the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 19 majority of the medium voltage events from OpE occurs 1 in the supply configuration and at the main bus bars 2 or the breaker stabs.
3 So there's a related concern here, which 4 is that a fault that is initiated at the breaker stabs 5 may not propagate through the tortuous path to involve 6 the aluminum that's present in the cabinet.
7 So both those concerns have been raised 8 both in terms of the prevalence of where these arcs 9 have started, as well as whether or not it will 10actually migrate to the aluminum presence in the 11 cabinets.12 So this has been discussed extensively by 13the working group. The NRC is essentially in 14 agreement that investigating the supply configuration 15 switch gear is worthwhile.
16So we have incorporated that as part of 17our tests to be conducted in spring 2020. So we're 18calling those our supplementary tests. And we are 19 going to test switch gear in the supply configuration 20 and on the main bus bars.
21 In regard to the operating experience that 22 shows the majority of the faults are on the breaker 23 stabs, the working group is in the process of 24 reviewing all of the, re-reviewing all of the data 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 20 from our phase one testing where we had nine tests 1that were, we had the arcs initiated on the breaker 2 stabs.3 And just from our preliminary review, the 4 members of the working group did think that there was 5 enough data on those breaker stab initiated faults to 6 use that moving forward for our modeling and for 7 estimating migration within the enclosure.
8MR. RANDELOVIC: Kenny, just to be clear, 9the data still has to be reviewed before we confirm 10 that we have enough information to, you know, to 11 inform the PRA guidance.
12MR. HAMBURGER: Right. So we looked at 13those tests. But we have not done a comprehensive 14 review of the data from those tests.
15MR. RANDELOVIC: Right. So just to be 16 clear.17 MR. HAMBURGER: Yes. Thank you. So, in 18 terms of that second point where the concern is that 19 a fault on the breaker may not migrate to the aluminum 20 in the cabinet, it's a legitimate concern.
21 But ultimately, the goal of our research 22 program here is to answer the Pre-GI, which is what is 23the impact of aluminum. So, if the aluminum is not 24 involved, it doesn't particularly provide us with any 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 21 useful answers.
1 However, recognizing that this is a 2 legitimate point, the working group's discussions have 3 focused around possibly handling that with a split 4 fraction ZOI to address the zone of influence for the 5 aluminum components if they're involved versus the 6 breaker if the aluminum is not involved.
7This one's an easy one. So we received a 8 comment that, from the OpE on low voltage HEAF events.
9 The events have all occurred in the load center supply 10 cubicle, which was not part of our initial test plan.
11The NRC is in agreement. So we have modified the 12 equipment that we've procured for the test plan to 13 include the supply cubicles.
14 So I already talked about one set of our 15 supplementary tests that we have slated for spring of 16 2020, and that's the supply configuration switch gear 17tests. We also have the generator decay curve tests.
18 And those were tests that were added to the test plan 19 at the request of our stakeholders.
20So, again, we're planning to do those. We 21 have contracts in place, correct? We have contracts 22 in place to perform those tests in spring of 2020.
23 So this was one of the comments we 24 received in several forms and in several meetings, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 22 which is regarding the modeling. So the NRC and the 1 working group are looking at the use of modeling to 2 help extend the range of applicability for the test 3 data.4 We can only test so many different 5 configurations and so many different parameters in 6these full scale tests. So we are looking towards the 7 modeling to help the working group evaluate alternate 8 configurations, evaluate the hazard sensitivity to 9 various parameters, and estimate conditions that maybe 10 can't be directly measured because of instrumentation 11 limitations.
12 So I'm not going to address the modeling 13 here. We have an entire afternoon dedicated towards 14 the modeling approach, data needs, modeling inputs, 15V&V. So I would ask that if there are any issues 16 related to the modeling that we hold those until the 17 afternoon presentations.
18 Measuring the conductivity of the cloud 19 has been an ongoing topic of discussion amongst the 20 working group. And it is not completely resolved at 21 this time.
22 The working group is exploring a number of 23 different measurement techniques that Nick and Marko 24 are going to speak to in slightly more detail. This 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 23is going to remain a focus of the working group 1 discussions as we move towards testing.
2 EPRI had initially suggested a mock switch 3gear that they designed. But ultimately and at the 4 current time, they felt that it has not been validated 5to be representative of plant equipment. And there is 6 not currently any funding to build the mock switch 7 gear units. So we have not moved forward with that.
8MR. MELLY: This is Nick Melly, Office of 9Research. Just to add on to that discussion, we will 10 be adding more detail.
11 We have an alternative way that we will be 12able to measure much of the same effects that that 13 mock switch gear will be looking at in a more dynamic 14measurement technique. And we'll be covering that 15this afternoon as part of the modeling. It's based on 16 a standard. And we think that we'll be able to move 17 that forward.
18 One important thing to note is that we 19 have a lot of ongoing activities. The working group 20is meeting weekly. And we are discussing all of these 21issues. The conductivity that I'm going to be 22 speaking about was actually the main topic of the 23 working group meeting last Thursday.
24 So these are real time developments that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 24 we are incorporating into the modeling, and we, 1 incorporating into the testing and modeling that we 2 hope will be successful.
3MR. HAMBURGER: One of the questions we 4 received was how are we isolating the impact of 5aluminum. This is being done in a number of ways.
6 For starters, we are, what we're testing is aluminum, 7 and that's the data that the working group is going to 8 use moving forward to create the hazard model and the 9 zone of influence model.
10 But to understand the specific impact of 11 aluminum as compared to copper, that is probably a 12 great use of our modeling techniques that you're going 13 to hear about this afternoon.
14 We've also done some small scale testing 15to identify the properties of the aluminum. And 16 subject to verifying that those small scale results 17 are scalable to large scale, that is a potential way 18 that we can isolate the impact of aluminum.
19 This was a recent comment during one of 20our working group meetings. But it's also been asked 21 by some of our international partners and other people 22 as we've moved along with our phase two testing, which 23 is why did we remove the heat release rate calorimetry 24 hood that we use during the phase one testing.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 25 There's a couple reasons that we've not 1included that in the test plan for phase two. The 2 first reason is that the hood does not capture the 3 initial blast.
4 So, if you've seen videos from our phase 5 one testing, the initial pressure pushes all of that, 6 those pilots of combustion out of the capture area for 7 the hood. So the hood does not capture that initial 8blast. What it does capture is the ensuing fire if 9 there is one.
10 There is a lot of heat release rate data 11available from our phase one testing. And what we 12 observe there is consistent with the current guidance 13for postulating ensuing fires. Does that -- would you 14 agree with that? So --
15MR. MELLY: For a subset of the tests, 16 yes.17 MR. HAMBURGER: Okay. So we don't see a 18 whole lot of value in continuing to collect this heat 19 release rate data. Less important than the value of 20the data is the logistics. But they're worth 21 addressing here. The location where we are planning 22 to initiate the arcs for our low voltage enclosure and 23 bus ducts, we are expecting the arc to move in the 24 vertical direction.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 26 So our test stands, I think I actually 1have a picture of that test stand I can show you. The 2 test stand is designed to capture the thermal energy 3 moving in the vertical direction.
4 So we have -- so our test stands are 5actually almost 14 feet high. And this precludes the 6 use of the hood. The hood won't fit over the top of 7those racks. It's not wide enough. It's not tall 8enough. And I'm not aware of another portable hood 9 that we could use.
10MR. MELLY: Yeah, and one of the main 11 reasons, again, for not including the hood in this 12 design is that we feel that there is a large amount of 13 heat release rate data from all the other electrical 14 enclosure tests that we have performed. There is as 15 well data from heat release rate for the high energy 16 arcing fault test that JNRA has performed.
17 So, logistically, putting a hood up that 18 we felt didn't capture the initial blast and only 19 captures the after-effects of the high energy arcing 20 fault was less important for the modeling techniques 21 that we're going to be following in order to evaluate 22 the source term of the high energy arcing fault.
23 So we're going to try and piece together 24 all the other information that we have, keeping in 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 27 mind that the KEMA facility is an electrical testing 1 facility and not a fire test facility.
2 These portable hoods are on the smaller 3end of the scale. And they're usually overwhelmed by 4 the initial blast of the high energy arcing fault, as 5 well as having a lot of challenges with being in an 6open air environment. We're losing a lot of the smoke 7 due to crosswinds.
8 And even having an ensuing fire lasting 9 for a long time in an outdoor test environment causes 10 some concerns environmentally with folks at the EPA.
11 We're not in a controlled environment like 12 NIST with smoke scrubbers and things like that. So, 13 having these longer duration fires is a challenge in 14 this, in the single test program.
15 MR. HAMBURGER: So I apologize. I can't 16pull up my instrumentation rack diagrams. The file 17 doesn't want to open.
18 But they're about 14 feet high and about 196 feet wide. So they're really, with the hood that we 20 used in phase one, there's really no place to put that 21 in the test cell.
22 And there's also a lot of complications 23 that come along with the use of those oxygen 24consumption calorimetry hoods. It takes about 100 man 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 28hours to construct and deconstruct that hood. We have 1 to transport compressed gas cylinders, sensitive gas 2analysis equipment. And there's frequent calibration 3 burn.4 So it's not as simple as just throwing the 5hood in there. So, if we're not going to get data 6 that we feel is valuable out of it, we've decided not 7 to include that in the test plan.
8So this is a big one. And there's a bunch 9 of people working on this as we speak. And that is 10communication with our stakeholders. This is a large 11and growing program. There are a lot of pieces to it.
12 And they come together in many ways.
13 So we've been asked to be much more clear 14 about what those pieces are, how they fit together, 15 the deliberations and details of the working group's 16 conversations and how they're dispositioning each task 17 and subtask.
18 So, to that end, we are working on a 19 website to improve communication in real time with all 20of the interested stakeholders. And this is going to 21 contain detailed data of all the tests and research 22 program components, how they fit together, the inputs 23 and outputs to each component, where the data flows 24 from component to component.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 29 Unfortunately, due to personnel 1 availability issues in the last couple weeks both from 2 EPRI, NRC, and Sandia, we do not have that ready at 3the moment. But you should expect to see that in the 4 next two to three weeks.
5 So we have taken that comment to heart.
6 And we are diligently working to put together a 7 comprehensive plan that details everything that's been 8 asked for.
9 So that is the end. And again, Nick and 10 Marko are going to cover some of these issues in much 11 more detail during their presentation.
12 But if you have questions that you'd like 13 to ask about comments that you feel were not 14 dispositioned or you'd like to bring up now, I would 15 invite you to come to the mic stand and ask away.
16 MR. GELLRICH: Ask away we will. George 17 Gellrich from Exelon.
18 You know, first off, you know, I just want 19 to acknowledge that this is a phenomena that has to be 20understood by the NRC and the industry. You know, we 21 do agree we have to understand the significance and 22 safety comes first.
23 I heard that you talked about, that you've 24 looked at the sites and now understand the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 30 configuration of the sites insofar as generators, 1 aluminum location, you know, is there single breaker 2 isolation from the safety bus.
3 So, with that data, like what's it telling 4you about the number of plants susceptible? Is it all 5 of them, some of them? Do we know that?
6MR. MELLY: So we're going to discuss that 7 in a little bit in the upcoming presentation. We've 8essentially tried to break it down into zones. And 9 we're going to feed that through our model.
10 In terms of our, which plants are 11 susceptible and which plants aren't, it really comes 12 down to a lot of underlying factors, whether they have 13 failures in their system or whether the design of the 14systems explicitly. Whether a generator circuit 15 breaker is installed in the plant design can have a 16 large effect of whether we see these generator fed 17 faults persisting for extended durations, which is 18 really what we're worried about in terms of the HEAF, 19 one of the primary parameters.
20 So I can't give you a number off the top 21 of my head as to 30 plants are at risk versus 70 22plants are not. But we're trying to take into account 23 the plant design in the way that we will be doing the 24 modeling, allowing for those contractors or anyone who 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 31 is postulating HEAF scenario to incorporate their 1 unique plant system into the potential outcome or the 2 zone of influence with an associated HEAF event.
3MR. GELLRICH: Okay. My concern would be 4 is I'm hearing this third hand but, you know, I'm 5getting an understanding that the number of actual 6 plants affected would be small, maybe less than 20.
7 And it seems to me that the research 8 you're doing should first understand what the 9 configurations are for the plants that really are 10 susceptible and then develop the research plan to 11 understand, you know, for those specific 12 configurations what the, you know, what research needs 13 to be done or what the plants could do to mitigate the 14 situation.
15 To, you know, to go forth as you are right 16 now and cast a wide net, you're spending a lot of 17 research money that may not produce valuable results.
18 You know, you talked about areas such as this testing 19 is worthwhile where we think this is legitimate.
20 Well, you should really focus your research on exactly 21 what you know and what you don't know.
22 So, you know, I'm very concerned that 23 you're really putting the cart before the horse --
24MR. MELLY: When you say susceptible, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 32 you're referring to the presence of aluminum?
1MR. GELLRICH: Not just, presence of 2aluminum is one aspect. But the configuration of the 3plant is a whole other one. Like many plants, the 4 generator, you know, goes out to the grid, but the 5 safety buses are all fed from an AUX transformer or 6 start-up transformer.
7Those I think would be taken off the 8 table. I don't know because I haven't seen the data 9 that you guys have pulled together as to what plants 10 are susceptible and which ones aren't.
11MR. MELLY: So we're going to be trying to 12 incorporate that into the design of the methodology.
13I wouldn't say that those situations are not 14 susceptible to having this extended duration high 15 energy arc fault.
16MR. HAMBURGER: Do you want me to pull up 17 the zone --
18MR. RANDELOVIC: There is an EPRI white 19paper that we just issued today. We went through 105 20plants in the U.S. And we classified all of those 21plants into eight different categories. The 22 categories are based on, you know, susceptibility to 23 HEAF, long duration HEAFs, and to the impact in the 24 class one buses.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 33 So we make a difference in that white 1paper. It was issued today, the difference between 2 generator fed designs and to the more complicated and 3 the more I would say less prone designs to the long 4 duration HEAFs.
5 MR. GELLRICH: Right --
6MR. RANDELOVIC: So there is a group of 7 eight different designs --
8MR. GELLRICH: Okay. So that, I think 9 that data would be critical to understand what 10 research you would want to do.
11MR. MELLY: Well, absolutely. And we are 12 trying to incorporate all that.
13 One important distinction also to make is 14 that we're not just talking about the susceptibility 15 to a safety bus having a high energy arcing fault.
16 There are some cases potentially out there where a 17 non-safety bus can still have a high energy arcing 18 fault where it is a risk significant contributor at 19 your plant if it damages safety systems in the zone of 20 influence or in the area of a hot gas layer 21contribution. So we're trying to look at all the 22 pieces together in order to inform our modeling.
23MR. GELLRICH: Yeah, and I think making 24 statements like you think that that's non-safety 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 34 related bus has a high risk significance, you know, my 1 experience would say that that probability is pretty 2 low.3MR. MELLY: But it's going to be all plant 4 dependent, scenario dependent depending on where that 5 bus is, what room that bus is in, and what is nearby.
6 One of the other distinctions to make that 7 we learned this actually at the last working group 8 meeting was that so far we don't have a very robust 9 understanding of which plants have aluminum 10 susceptibility, which plants do not. We have --
11 MR. GELLRICH: Exactly.
12MR. MELLY: But we have an informal survey 13 done by NEI which showed that there was a fairly large 14 contribution of aluminum in the plants.
15 But speaking with one of our experts on 16 the working group panel, he said it was very difficult 17 for him even to ascertain whether he had aluminum in 18his main switch gear supply. He had outdated specs 19 for his cabinet itself, the 4160 volt cabinet.
20 However, when he dug through the information, it was 21 found that he did have aluminum in that bus work for 22 the main supply.
23 So, if you asked ten people in his plant, 24nine of them might have said, no, we don't have 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 35aluminum in this cabinet. However, by digging in and 1doing the work, they found out they actually did. So 2 that is one issue --
3 (Simultaneous speaking.)
4MR. GELLRICH: -- and understand 5specifically. We should hold ourselves accountable as 6 an industry to really understand the configurations 7 and then base the testing on that configuration.
8 I think putting the research before we 9 understand what we have is exactly what we did with 10GS191. Okay. GS191, with strainers, apply to all 11plants. And then the NRC did research. And then each 12 plant had to do their own research to validate what 13 aspects of that research applied to their specific 14sites and which ones didn't. And it was an immense 15 waste of resources.
16 And, you know, my point is I think we're 17following that pattern again. And we should step 18back, understand what the configurations are. We owe 19 it to you to understand that configuration and then 20 figure out what realistic testing we need to do.
21 I'm concerned that the availability and 22 test facility is putting time pressure on all of us.
23 And we're going to do this research, and we're going 24 to step back, and we're going to be in a position of 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 36not understanding what the real applicability is to 1 all the sites. And then the sites are going to have 2 to go off and do their research on their own and 3 recreate research, which is not where we want to be.
4MR. HAMBURGER: So I think to some extent 5we've done that. I mean, the working group has looked 6 at every single plant and broken them down by 7 susceptibility and what the HEAF would look like in 8 various locations in that plant. Are you suggesting 9 looking at other aspects of the configuration?
10MR. GELLRICH: No. I'm hearing we just 11 finished this paper today.
12 MR. HAMBURGER: Okay.
13MR. GELLRICH: So how can we be doing 14 testing if we haven't even looked at the results in 15 the paper?
16MR. TAYLOR: This is Gabe Taylor, NRC 17 Office of Research. So I'm not, I haven't looked at 18what EPRI published today. But January last year they 19did publish two white papers. And in one of those 20 white papers, they did do an evaluation that broke 21 down the electrical distribution system into different 22 zones.23 Now, I'm guessing the difference between 24 what was recently released and that paper was they 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 37 focused on safety-related equipment in the -- no?
1 Ashley is going to correct me.
2MS. LINDEMAN: This is Ashley Lindeman 3from EPRI. So, just to back up one step, the 4 consequential events that we've seen in the operating 5 history are on the non-safety switch gear. And they 6 have been due to a generator fed fault.
7 With that said, the EPRI white paper that 8was published, Rev 0, had around 60 sites. But we got 9105 sites, so pretty much everything. And we 10 classified them from high susceptibility to really 11 lower or not applicable.
12 So, in the lowest susceptibility, there 13are 63 plants. And those are plants that feed from 14 the station, the AUX transformer, you know, from the 15 grid. So it's not running from the house loads.
16 So right away, you know, 60 percent of the 17 plants aren't really susceptible to the generator fed 18fault. An additional 11 have circuit breakers, 19 generator circuit breakers that may interrupt the 20 generator fed fault.
21 So now we're left with roughly 30 sites.
22 And six of those sites I think or less have safety 23buses that may come from the house. So the population 24really gets smaller and smaller. So I just wanted to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 38 provide some context for everyone.
1MS. VOELSING: Ashley, when you started 2 you said that the consequential events that we've 3 seen.4 MS. LINDEMAN: Yes.
5 MS. VOELSING: You mean consequential in 6 terms of having long durations --
7MS. LINDEMAN: Oh, sorry, yes. When I say 8 consequential, I mean from a damage perspective or the 9 HEAF may have damaged components outside of the 10 component origin, not necessarily from a risk 11 perspective. So --
12MR. MELLY: Yeah, and Ken just put 13something on the screen here. This is kind of a 14 preview of some of the information we were going to 15 cover in the next presentation is we are trying to 16 take these actively into consideration of the 17 methodology that we are going to develop for the high 18 energy arcing faults.
19We're going to try and take into things 20 like whether the plant has the generator circuit 21 breaker, what the design of the plant itself is, what 22it's fed by, whether it's the unit auxiliary 23 transformer or the site auxiliary.
24 We're taking into account things like the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 39circuit breaker, whether it's apply or load. And 1 we're trying to let the actual in-plant design inform 2 what our overall duration potential is, as well as 3 then how that feeds to the overall zone of influence.
4 So, for some of these plants that are less 5 susceptible or for some of these plants that don't 6 even have aluminum, this might not be an issue that is 7of a grave concern. However, we are trying to let the 8methodology lead us to that discussion and that 9 decision rather than bringing that to the forefront.
10MS. VOELSING: Yes, so this is Kelli 11 Voelsing from EPRI. If I could, I don't want to put 12 words in anybody's mouth, but kind of summarize what 13 I think I'm hearing, which is, you know, Ashley has 14 presented that, you know, we're talking less than 30 15plants that have a bus susceptible to this. And of 16 those, you know, not all of those are safety-related 17 buses and, therefore, may be less risk significant in 18 the PRA.19 And, you know, as George pointed out, of 20 those, you know, 10, 20, whatever it is number of 21 plants that might be susceptible to this, we haven't 22 validated which of those have aluminum and which of 23 them don't.
24 And we absolutely agree that from a, you 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 40 know, a methodology, a PRA standpoint, a technical 1 approach, that, you know, understanding that and 2 building all that into the methodology is the right 3 thing to do and we support that.
4I think, you know, maybe what George is 5 saying is, you know, how generic really is this on the 6front end. You know, I think we could do some more 7 work as an industry to answer that question.
8 MR. MELLY: Yeah, the only clarification 9 I want to make to this discussion that we're having is 10 we're throwing out numbers like 30, 40, 20 plants are 11 susceptible to generator fed faults.
12 We are as a working group also taking into 13 account things like circuit breaker failure or 14 protection scheme failure into effect as well.
15 So a plant that might not seem susceptible 16 can still have a lower probability of having 17additional failures, which might then open the door 18 for having this potential. But we're trying to deal 19 with it in the probabilistic way by looking at what 20 that rate of failure is and incorporating that into 21 the methodology.
22 That may address the issue explicitly.
23 And it may lower the potential risk enough that it 24might not be an issue for a specific site. But we're 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 41 hoping that the methodology and the zone of influence 1 and the hazard modeling will actually inform that 2 decision.3MR. RANDELOVIC: So the model that we are 4 building right now is basically very similar to 5 internal events, PRA, where you have an event and you 6 have, you know, different protection systems and you 7 are crediting different protection systems to mitigate 8those events. And then based on the success or 9 failure of those, of the protection system, you have 10 different end states.
11 In this case, we are doing exactly the 12same. You are crediting, fully crediting the 13 protection scheme based on the specific designs that 14 you have in your plant.
15 So it's fairly complex in the integrated 16 methodology that we will provide that will basically 17 provide insights on, you know, bridging the gap 18 between the OE, what we are seeing in the OE, and 19 incorporating the design of the plants --
20 MR. MELLY: Yeah, that's --
21 MR. RANDELOVIC: -- in the methodology.
22MR. MELLY: That's one very important 23 aspect. In this specific approach that we're doing, 24 we're actually pulling in insights from the operating 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 42event experience and the fire events database. So 1we're trying to merge the plant design, the OpE of 2 what we've seen, and allow that to inform the result 3 and how we're going to be performing our scenario 4 modeling.5MR. HAMBURGER: So I think we may have 6just addressed this. But we did have a question on 7 the webinar from Tian Fenglin, which is there are very 8 few aluminum buses in the plant so why are we 9 researching aluminum, if you want to add anything to 10 that.11MR. MELLY: So, based on the informal NEI 12 survey, we've seen that there are aluminum concerns in 13 medium voltage switch gear, low voltage switch gear, 14 and the bus ducts themselves, as well as bus ducts 15 enclosures.
16 So the generic issue process is triggered 17when it is two or more plants. And we have identified 18 two or more plants that do have aluminum concerns or 19 the potential of concern for aluminum interaction 20 within a high energy arcing fault environment.
21 MR. HAMBURGER: Go ahead.
22MR. RISHEL: Bob Rishel from Duke Energy.
23 So, on the comment about the vertical effect of the 24 high energy arc fault, so my OpE is all, all our 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 43 faults I have seen or had in our plants have been 1horizontal events. Very little damage has ever 2occurred in the vertical direction. And so I was 3 wondering why we're putting so much effort into that.
4 It seems to be --
5 MR. HAMBURGER: Are you referring --
6MR. RISHEL: It seems to be technically 7 wrong.8 MR. HAMBURGER: Are you referring to bus 9 ducts as well or are you just referring to switch 10 gears and load centers?
11MR. RISHEL: -- switch gear, you know, 12 cabinet, high energy arc faults.
13 MR. HAMBURGER: Okay.
14 MR. RISHEL: If you look at breaker stab 15 interactions, that's a horizontal event.
16MR. HAMBURGER: Okay. So you're not 17 referring to the bus ducts. You're okay with --
18MR. RISHEL: Not referring to the bus 19 ducts.20 MR. HAMBURGER: Okay. Great. So --
21MR. RISHEL: But your testing 22 configurations, like cabinet high energy arc faults.
23MR. HAMBURGER: That's correct. Okay. I 24 just want to clarify the scope of your question.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 44MR. RISHEL: And I would point out also in 1 another separate comment on your fault propagation, 2 having been intimately familiar with the Robinson 3 events, the Robinson event was stopped by the 4 transformer itself.
5 So, if you're talking about protection, 6 don't forget that those transformers are not 7infinitely capable of propagating faults. They do 8 have a point at which they will stop.
9 MR. MELLY: Right. And in that Robinson 10 event, that point as discussed in a previous slide, we 11 were talking around, on the order of 8 to 12 seconds.
12MR. RISHEL: Correct. But there was no 13 vertical damage by the way. And --
14 MR. MELLY: Yes.
15MR. RISHEL: -- additionally, the way that 16 that fault stopped was that the transformer failed.
17MR. MELLY: Yes. And we are trying to 18 take these into consideration in our modeling 19approaches. We're looking at the OpE as to whether it 20 occurred on a breaker stab versus a different point 21 within the cabinet. And we're going to be trying to 22 incorporate that potentially with a split fraction, as 23 Kenny mentioned, as to where we believe that occurred.
24 However, from testing, we do see that it 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 45 is possible to orient the arc in the vertical 1 direction depending on where the arc is initiated 2 within the cabinet, what the magnetic field is in the 3 cabinet itself, and where that arc initiation point 4 is.5 But you are correct in that we see the 6OpE, a lot of it is at the breaker stab. And we're 7 trying to take that into account when we move forward 8with the methodology. So, hopefully, we will be 9 addressing that issue.
10 MR. HAMBURGER: Gabe, do you want to say 11 anything about where we're initiating the arc for low 12 voltage and why we're expecting it to be a vertical?
13MR. TAYLOR: Sure. So, for the test we 14 have planned, we have a piece at Westinghouse DS 15series gear. And the gear that we procured, it has 16 vertical bus bars and horizontal bus bars on the main 17 buses. And the verticals are aluminum. And per the 18 procurement document, the horizontals are copper.
19 So, because of the vertical aluminum bus 20bars, we are planning to initiate them at the top, 21 because that's the predicted, expected migration point 22of the arc. So, for that case and that piece of 23 equipment, we planned on initiating it there.
24MR. RISHEL: But I would just question, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 46 you know, so most of the cabinets I have seen, the 1 connections are towards the bottom or maybe the middle 2 not, there's no connections towards the top of the 3cabinet. The bus bars come in or the connections come 4in the top and typically go down. And the connections 5 are, the stabs or whatever are towards the bottom or 6 middle at the worst.
7 MR. TAYLOR: So --
8MR. RISHEL: So why initiate the fault at 9 the top?10MR. TAYLOR: So, for the -- you're right.
11 For the incoming and outgoing cable connections to a 12 low voltage gear, typically the connection points are 13 going to be at the lower portion of the gear.
14 However, internally where you have the 15 drop, the runbacks to the breakers, they're going to, 16 for feeders, they're going to be at any height where 17you have a feeder breaker. For the supply, they're 18 typically going to be somewhere in the middle or lower 19 portion.20 So, depending on how the power flow is 21 within the breaker and where the arc is initiated at, 22 that's going to predicate where the arc is going to 23 migrate to. It's either going to stay where the arc 24 initiates or the magnetic forces are going to push it 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 47 away from the incoming power supply.
1 So, based on the design of the equipment 2 that we procured, all that type of information is kind 3 of influencing us that the arc's going to migrate to 4 the top of that cabinet.
5MR. HAMBURGER: And I just want to add one 6more thing. Although we are now placing two 7 instrumentation racks above the cabinet because we're 8 expecting that thermal energy to be directed upwards, 9we are still measuring at horizontal stands. So we're 10 not neglecting the horizontals.
11MR. RISHEL: Actually I'm just worried 12 we're going to draw the wrong conclusions about the 13 industry and electrical cabinets if our testing 14 emphasizes vertical direction versus horizontal 15 direction.
16 MR. MELLY: So we're not saying that the 17 energy, we're not saying that it's going to be 18vertical in every single case. We are just -- we take 19a look at the cabinet that we did procure. And we are 20 taking our best estimate as to where we think that arc 21 will have the highest impact on our instrumentation.
22 And we believe right now with the cabinet 23design that it will go in the vertical direction. So 24 we're placing multiple instrumentation test stands 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 48there. However, we will be placing them in the 1 horizontal direction as well if the arc actually moves 2 in the horizontal direction away from the cabinet.
3 Now, that being said, just because this 4 specific test we believe it's going to go vertical, we 5 are not going to be influencing the methodology to say 6 that all high energy arcing faults will show the 7highest risk in a vertical direction. That is not the 8 intention of linking the modeling to the testing.
9 MR. HAMBURGER: It's essentially an --
10 MR. RISHEL: So why do it?
11 MR. HAMBURGER: Because --
12 MR. RISHEL: Why spend money on that?
13 MR. MELLY: Because we want to make sure 14that we have adequately measured the source term. And 15 we believe in this test the ejecta or that plume that 16 we're going to see the highest impact or, is going to 17 go in the vertical direction.
18 So, by measuring the source term 19 adequately, we can inform the modeling so that we can 20 know what the source term would look like in any 21 direction of the cabinet because it is probabilistic 22 as to where that arc will initiate.
23MR. HAMBURGER: It's essentially an 24experimental concern. We have a limited number of 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 49test stands. We have to put them where we think we're 1 going to measure the most valuable data.
2MR. MELLY: So, and for instance, the test 3 that we just performed in 2018, all of the, most of 4 the ejecta was in the horizontal direction away from 5 the incoming power supply in the cabinet.
6 We had our two test stands in the 7horizontal direction at three-foot, six-foot. But 8 that single test where it shot in that direction at 9 the back of the cabinet is just for that experimental 10 test 7. It allowed us to measure the source term of 11 that HEAF.
12 But we're now not saying that all medium 13 voltage is going to go to the back of the cabinet in 14one direction. We're allowing the modeling to say 15 where in that cabinet we'll expect to this zone of 16 influence and what could potentially be in that zone 17 of influence. So we're not trying to --
18MR. RISHEL: Shouldn't the direction be 19 largely by the cabinet construction --
20 MR. MELLY: Configuration dependent.
21MR. RISHEL: -- configuration and also two 22 things? One is how strong is the short, right?
23 MR. MELLY: Yes.
24MR. RISHEL: What is the capacity of that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 50 short, right?
1 MR. MELLY: Yes.
2MR. RISHEL: You know, some are incidental 3 contact where there's just fractions of inches 4 connection, which is enough to start the event, and 5 some could be more. So it seems to me that's pretty 6 important input.
7MR. MELLY: I agree. And that's why we 8 are altering the current, the duration of the tests, 9 and the voltage so that we have a full picture of the 10 important parameters that are going to impact the 11 energy release of that event.
12MR. RANDELOVIC: And we are discussing 13 about procuring the vertical racking designs versus 14 horizontal racking designs --
15 MR. MELLY: Yes.
16MR. RANDELOVIC: -- which is also 17 different configurations and we have to be able to 18 provide additional insights of how --
19 MR. MELLY: Yes.
20 (Simultaneous speaking.)
21MR. MELLY: That is a very important 22 aspect that configuration is something we're trying to 23take into account. Not only are we testing the, where 24 we tested in 2018 at the rear of the cabinet. We're 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 51 going to be testing the supply configuration, which 1 has a different enclosure around it, a different set-2up of the bus bars themselves. We're testing the low 3 voltage in this vertical.
4 But we're not allowing the tests, 5 experimental set-up, to influence what we're going to 6 be coming up with in terms of the generic model. So 7 we're trying to take these into account as we move 8 forward.9MR. HAMBURGER: Mike, did you want to say 10 anything? Hit the button.
11MR. CHEOK: So we hear all these comments.
12And I think it's important. I think what we also need 13 to keep in mind is that we are now in the pre-generic 14issue phase. So what we are doing is we are not 15saying that this is a generic issue. We have seen 16 that an issue could be of safety significance, could 17 be or maybe.
18 We are not saying that it applies to all 19plants. As a matter of fact, we know that it doesn't 20 apply to all plants.
21 We are just trying to determine -- so this 22is an issue, and we will take risk into effect. We 23 will determine what the test parameters are as a 24 different, on a different track.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 52 We are also looking at the frequencies of 1 the different configurations and the frequencies of 2initiation given the different configurations. And we 3 are also, you know, taking into account and working 4with our counterparts in EPRI on what mitigative 5 actions that the industry is doing to lower the 6 frequencies.
7 And, you know, all those will be taken 8into account at the next phase. I mean, the next 9 phase is given the fact that this is potentially what 10 we see out there with the different configurations and 11 what are the frequencies and if plants have these 12configurations what are they doing to lower the 13 frequencies in terms of the source term, in terms of 14 the targets.
15 I think what we are trying to do here is 16 get enough data to inform ourselves whether this is a 17 generic issue or not.
18MR. GELLRICH: Yeah, Mike, George 19Gellrich. Just my comment on that would be that, you 20 know, from our perspective it would be better in the 21 pre-generic phase of this is that we should understand 22 what configurations are out there first and then do 23 the research versus, you know, going off, hey, we 24 think this might be a configuration or it might go 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 53 horizontal or this or that.
1 I mean, it's, you're casting a very wide 2net. And quite frankly, I don't know whether you have 3to or not. You might be able to use the research that 4 was done by EPRI and yourselves and determine, hey, 5 these are the specific configurations we really need, 6these are the plants that show the issue, and deal 7 with those.
8 I just think we're coming up with out-of-9 the-box ideas and we d on't know whether they're 10 applicable or not.
11And what the result will be is you'll 12 publish it, and it will get everybody spun up around 13 the safety significance of this issue. And it won't 14be realistic. When you apply it to the plants, you'll 15find out, oh, some, number one, it doesn't apply. And 16 then there's going to be a handful of plants that have 17to do something. So that would be my opinion.
18 Thanks.19MR. CHEOK: Thank you. So I think I just 20wanted to make one comment on that. We will not 21publish the results of the tests without context.
22 That's something we will not do.
23We will publish the results. You know, we 24 will continue to work with all our stakeholders as to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 54properly quantify the risk significance. And the risk 1has to be, as you all say, plant specific. And it 2 will not apply to all plants.
3 And, you know, so we will have, we will 4 not -- we understand that, you know, the data by 5 itself is not the results of what a HEAF would look 6like. We understand that the risk incorporates and 7 encompasses a lot of different elements.
8 And we will take into account all those 9 elements before we even publish any results or make 10any kind of recommendation as to whether this is a 11generic issue. And even then, you know, we will have 12 all our results characterized in the risk-informed 13 way.14 And so the other thing I was kind of 15 listening to was, you know, the placing of the 16 different detectors, whether it's vertical or 17 horizontal, is not that, relatively speaking, not that 18expensive to do. It's the test itself that causes the 19expense. Whether we put additional detectors, 20 vertically or horizontally or something, that doesn't 21 add that much more to the cost.
22 So, if we were going to perform a test, it 23 would be more beneficial for us let's just say to, you 24know, get all the data we need. And a lot of the data 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 55 may not be applicable. And we will be sure to state 1 that.2 But if we perform a test and not take all, 3 not get all the data we can get, it might be an 4 opportunity lost if we have to re-perform a test 5 again.6MR. HAMBURGER: Okay. Tom, do we have 7anything on the webinar? No? Okay. If there are no 8 more questions, at this point we go to break here 9 unless you want to start.
10MR. MELLY: I just want to add one more 11 clarification that I just thought of in terms of the 12 directionality of the zone of influence as we've been 13 talking about.
14 So, in the 6850 methodology, it's three-15 foot, five-foot, three-foot horizontal, five-foot 16vertical. The working group thoughts initially during 17 our discussion was that that difference in the three-18 foot, five-foot, having an increased vertical zone of 19 influence due to these HEAFs, was largely due to the 20 fact that that methodology was created because it was 21 an investigation of post-event experience.
22 So you're seeing not only the damage from 23the initial blast. But you're seeing the larger 24 thermal damage from the ensuing fire. And it's very 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 56 difficult to look at an accident investigation after 1 the fact or root cause investigation and separate 2 those two out and say that this was the thermal fire 3 after versus the blast at the very start.
4 Our initial thoughts are that there 5 shouldn't be an initial difference in the horizontal 6versus vertical direction. So we're not talking about 7 potentially three-foot, five-foot or things like that.
8 We're thinking of these things actively, but maybe we 9don't have a difference in the vertical towards 10 horizontal.
11 And we're taking all that into account in 12 the way that we're going to be looking at the data, as 13 well as performing the methodology and modeling as we 14 move forward.
15MR. RISHEL: So, on the zone of influence, 16 so to speak, so, you know, I'll go back to the 17 Robinson event.
18 So we actually sent Sandia the cables that 19 were in the zone of influence, actually three inches 20above the top of the cabinet. And Sandia sent us back 21 a letter that says those cables are not faulted, that 22 they're perfectly capable of continued service.
23 And there was a little heat damage on the 24outer jacket of the cables. But that would tend to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 57 say that there's, in that case, almost no vertical 1 impact.2 And in fact, there was a panel two and a 3 half feet away from the faulted cabinet that had 4 splatter on it and had a plastic gauge cover on it.
5And that plastic gauge cover was not melted. It was, 6and it showed some damage. And it had some splatter.
7 It wasn't melted. The cabinet was undamaged.
8 There was a construction fence some 9distance away that was melted. So, when the hot 10 material deposited on, essentially, you know, like a 11 coke bottle, construction was great, that thing was 12 gone.13 But everything else, there was no damage 14 other than the inside of the cabinet was totally 15burned out. And the next cabinet over also showed 16 damage.17 So, when we talk about ZOI, we need to be 18 very careful about it, because it isn't three-foot, 19one-foot cone of death. It's probably almost no cone 20 of death frankly.
21MR. MELLY: And I hope that the working 22 group efforts and our efforts to increase the realism, 23 as well as put forward the methodology, will address 24 those types of issues.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 58MR. HAMBURGER: Yeah, I think everybody is 1 in agreement that the one-size-fits-all model is not 2 the state of the art. And we're working to get away 3 from that.
4Okay. Let's take a break until 10:30. I 5 forgot to put the sign-in sheet up on the podium over 6there. So, when you come back in at 10:30, if you 7 could do me a favor and please sign in so we have an 8 accounting of who attended today.
9 If you're NRC staff and you wouldn't mind 10 escorting people up and down from the lobby so they 11 can get some coffee, I would appreciate that.
12 (Whereupon, the above-entitled matter went 13 off the record at 10:09 a.m. and resumed at 10:27 14 a.m.)15MR. HAMBURGER: So, Nick and Marko are 16 going to provide an update on the Working Group status 17and their activities. And we'll be expanding on some 18 of the topics that were addressed in the first 19 presentation.
20 If you didn't get a chance to sign in, on 21 your way back in please just do that before lunch, if 22 you don't mind.
23 So, Nick, go ahead.
24 MR. MELLY: All right. So, we wanted to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 59 give a kind of high-level overview of some of the 1activity of the Working Group. As Mark said, we do 2 have a lot of activity going on. We have our weekly 3 meetings as well as we've had several in-person 4 meetings to discuss how all of these pieces are going 5 to come together. We are going to be discussing the 6 mission of the Working Group, some of the PRA modeling 7 approaches that we are going to be investigating, as 8well as updating. We're going to look at some of the 9 lessons learned from the operational experience 10review. We're going to be discussing some of the 11 testing approaches, as well as discussing our planned 12 project plan that Kenny has alluded to previously.
13 So, out of this information we have 14 discussed previously as part of the Working Group, the 15 mission/charter of this Working Group is to improve 16 the understanding, the risk from high energy arcing 17faults in nuclear power plants. The goal of our group 18 is to understand some of the key factors. That 19 includes the occurrence of high energy arcing faults 20or the frequency, as well as the severity. So, in 21 that regard, the zone of influence.
22 And we want to advance the high energy 23 arcing fault PRA modeling. We are going to be using 24 the experimental data, operating experience, and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 60 engineering judgment in coordination with the 1frequency to get a more robust model. We are not 2talking about creating a one-size-fits-all. We are 3 trying to push forward, so that we can actually 4 understand plant insights, OpE, the specific 5 characteristics that are going to affect a specific 6 high energy arcing fault scenario, so that we can 7 tailor that to get a unique zone of influence for that 8 particular place within your plant.
9 We're going to also, then, be talking 10 about analyzing the plant impact and risk 11implications. That gets towards the pilot plants that 12 are going to be part of the Working Group activities 13 into further understanding what the risk from these 14events are. That is part of the generic issue 15 assessment plant currently, to perform pilots.
16 And one of the issues that we previously 17 did bring up of trying to do a better job of 18 understanding those plants that could be at risk, 19 those plants that do have aluminum, I would highly 20 recommend that the industry does take a more 21 standardized or robust measure of trying to figure out 22 which plants do have aluminum, where it is, what 23 configuration it is in, because that will only help us 24in terms of selecting pilots and performing those 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 61pilots as we move forward. So, if there is an 1 industry effort or a renewed industry effort to get 2 better data associated with where we do see aluminum 3 and where these sensitivities could be, we welcome 4 that type of work.
5As I said, we do hold weekly meetings.
6These are more involved. We pushed them forward from 7 biweekly, one hour, to weekly, two-hour meetings 8 because we've seen that we just have so much material 9 to cover and we need to keep active progress in order 10 to push our testing forward, as well as to understand 11 the data that we are collecting.
12We have discussed the project members. We 13 have Ken Fleischer, Dane Lovelace, Shannon Lovvern, 14Tom Short, Marko, and Ashley. We have Dr. Hyslop, Dr.
15 Chris LaFleur, myself, Kenn Miller, and Gabe Taylor.
16 And that's just the main team members.
17 In terms of support, we have a lot of 18 other members who are doing some data analysis at 19Jensen Hughes. We have Ken Hamburger. We are pulling 20 in all the resources that we need because this is an 21 unevolved process. We're putting a lot of resources 22 towards this to solve the issue.
23MR. RANDELOVIC: Now the next couple of 24 slides, we will be discussing some of the Working 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 62 Group activities.
1 The first one that we would like to bring 2right now is the HEAF methodology report. Basically, 3 the report will contain the details and the test 4results, the operating experience, insights. And that 5 report will be basically used to implement the HEAF 6 PRA methodology for the plants.
7 So, we have initiated this report by 8 performing initially the extensive review of all of 9the OE in the U.S. Out of that extensive review of 10 the OE, we have gathered a lot of insights regarding 11the fault durations, the fault locations. Is it in 12 the supply or load configuration? The accident 13 sequences that we are getting the insights for to 14 inform our decision trees and event trees.
15 So, that is the first kind of section of 16 the report. That data from the operating experience 17 is not only used to develop the methodology, but also 18 to inform the testing.
19 Then, there's another section which is the 20HEAF frequency. So, we reviewed the 30 events. We 21 sat down for hours and days looking at every single 22 event and classified this as Bin 16.A, 16.B, 16.1, 23 16.2, and like whether it is an arc flash, arc blast, 24or HEAF. So, we have been through all of that effort, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 63 and we believe that at this point we have a fairly 1 good knowledge regarding those events and how those 2 events will be used for the frequency calculations.
3 And lastly, the risk model development.
4 So, as I said, initially, we had Version 1 of the EPRI 5 white paper where we had the different designs of the 6 electrical distribution systems in the plants in the 7U.S. Revision 2 has been issued today. And so, we 8 are going to use the design, specific designs from the 9 plant with the operating experience to come up with 10 the realistic model that moves away from one-size-11 fits-all and, basically, incorporates and integrates 12 the insights from the OE and the protection scheme 13 from the electrical distribution systems.
14MR. MELLY: This is kind of a snapshot of 15 some of that work that we performed. We did spend a 16 significant amount of time trying to understand these 17events. And you can see up here on the screen, we did 18 an extensive review, and we're trying to classify 19those. We're trying to understand the duration, which 20 is one of our primary parameters.
21And for some of these events, we found 22 that it was very easy to actually come up with a 23 defined duration from the event report itself or 24 potentially the LER, or even going back and collecting 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 64more information. So, we have been able to nail down 1 the duration for some of these, and hopefully, that 2 will feed into our modeling approach.
3 You see here that we have some bolded 4 event durations which are from 4 to 8 seconds. Some 5of these are alluding to the fact that these are 6generator-fed faults. And that 4-to-8-second duration 7 is an estimation.
8 We have a current Working Group action 9 item to try and pin that down a little bit better, in 10 order to reduce our uncertainty associated with that 11time duration, but it is fairly difficult to 12 understand these generator-fed faults and what the 13 actual duration was because they're from a long time 14ago. They may not have had digital fault recorders in 15place, and it is going to be generator-specific. So, 16 we are trying to pin that down in order to understand 17 the OpE and what the OpE is showing us, and how we're 18 going to incorporate that into our model.
19 One of the important distinctions that we 20 need to make here that has been brought up in previous 21 Working Group meetings, previous public meetings, is 22 that we are not focusing on these millisecond fault 23occurrences. They're not part of our current HEAF 24frequency bin. If we're talking about an arc fault 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 65 only persisting on the order of cycles, that's not 1going to be included in the frequency for how we're 2 treating high energy arc faults. Those are types of 3events where their circuit protection does work as 4 designed, and the arc is immediately extinguished, 5causing very little damage. That is not what we're 6 talking about in terms of HEAF and is not what we are 7going to be modeling or testing. One of the important 8 aspects is that the OpE did show more generator faults 9 than we had typically thought were out there just from 10 our extensive review.
11 What we have shown here on the screen here 12 is how that fault duration, the current breakdown of 13what that duration looks like. We see several unknown 14 events, but, then, on the X-axis, you are looking at 15the duration of fault in terms of seconds. And you do 16 see that we have a large item pegged at that 4-second 17estimated duration. That's identifying these 18 generator-fed faults.
19 And we do hope that the methodology that 20 we're going to present will capture those plants that 21 are more susceptible to generator-fed faults versus 22 plants that are not susceptible or less likely to be 23susceptible. And we're hoping that this kind of 24 distribution potential for the duration will allow us 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 66 to pinpoint where susceptibilities in the plants are 1 in terms of which cabinets or which lineups can 2 actually have this extended-duration high energy 3 arcing fault event.
4MR. RANDELOVIC: Just to add something, so 5 because we have these fairly large uncertainties on 6 the generator-fed faults, I took an action to go back 7 to some of the plants that experienced the generator-8fed faults, asking for specific duration. I only 9 found one plant that provided some additional data and 10 confirming that the fault was between 4 and 6 seconds.
11 The remaining plants, unfortunately, didn't have 12 enough details or information to supplement this 13 assessment.
14MR. MELLY: And the current estimation is 15 based on some information that was gleaned from the 16 event that occurred at Maanshan, where some of the NRC 17 electrical experts said that a generator-fed fault in 18 that condition could have persisted somewhere 4 to 8 19seconds. So, we hope to do a little bit more work in 20 that area to pinpoint that, if we can't get more 21 information from the plants.
22 MR. RANDELOVIC: Do you want to expand a 23 little bit the estimate, how we came up with the 24 estimated durations for the other events? Two 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 67seconds, 4 seconds. So, we basically went into every 1single event and looked. We had Ken Fleischer and 2Dane, electrical experts, looking at what type of 3 system, protection systems, performed to mitigate a 4fault. And based on that knowledge, and based on the 5 selective coordination and the protection scheme 6 designs, they were able to provide kind of an 7 estimated, the maximum estimated duration, given the 8 sequence and the sequence of events for a given HEAF 9 event.10MR. MELLY: Moving forward again, as part 11of this, we were looking at low voltage. And part of 12 our question here was, what do we test for low 13 voltage?14 In the April Working Group of 2018, it was 15 said that these 8-second tests for low voltage are 16 unrealistic because we have so many levels of 17 protection before we can actually have this 8-second 18 fault. What we have identified from the OpE is that 19 there are several cases out there where we can have a 20 prolonged-duration event with the low voltage if we're 21 at a certain point of the protection scheme.
22 So, we specifically are trying to link our 23 testing parameters in terms of current and voltage to 24those areas where we might see an extended-duration 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 68event. For the upcoming tests, we're going to be 1 performing at 13.5 kA for these low-voltage tests 2 because it was seen from the operating experience and 3 from actual plant configuration that we could run into 4 a case where you can have between, I believe it was 8 5 kV, 13.5 kV, that could last for an extended duration 6 up to 8 seconds, looking at the specific configuration 7of that breaker design. So, we are trying to take 8 into account these situations.
9 Another piece of information that we hope 10 to be able to glean from, if we go back to the low 11 voltage, from the extended-duration event is, we can 12only perform the medium-voltage tests at the KEMA 13facility up to 4 seconds. The generator is simply not 14 large enough to perform anything larger than 4 seconds 15on medium voltage. But, for low voltage, we can go up 16 to 8-10 seconds, just based on the generator size.
17 So, we are hoping that some of the low-18 voltage information at extended durations, we'll be 19 able to inform some of the modeling for medium 20voltage. Again, that's an extrapolation. It will not 21 be straightforward, and that's going to be an action 22 item for the Working Group to even evaluate where we 23 can make that potential extrapolation.
24 So, those are the two reasons why we do 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 69 see a benefit for testing some of the low-voltage 1 cases at 8 seconds, which is our maximum duration of 2 our test series.
3 Next slide.
4MR. RANDELOVIC: So, for the medium-5 voltage tests, EPRI, following our assessments of the 6 OE, made a comment back in January regarding the 7location of the fault. In the previous run of tests, 8we have located the arc wire at the buzz bars. And 9 looking at the OE, basically, the majority of the 10 medium-voltage switchgear HEAFs occurred at the 11 breaker slabs, where you basically don't have the 12aluminum. So, the majority occurs at the breaker 13slabs. Some of the events, we have the fault 14 initiated in the main buzz bars; in only one event on 15 the back bars.
16 So, we have brought those insights to the 17 Working Group, and we have discussed on the path 18forward for the next round of tests. For the breaker 19slabs location, we have decided to look at the OECD 20 data. It looks like there were some tests performed 21at the breaker slabs. However, we still have to 22 evaluate the amount of data that could be used to 23 define the zone of influence. And there's an action 24 item for Energy Research to send to the Working Group 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 70and send the other data. And then, we need to 1 evaluate if we have enough information to come up with 2 a realistic zone of influence. If not, then we will 3 have to decide how to proceed.
4 So, the testing for the medium-voltage 5 tests in 2020, the Working Group has decided to 6 proceed with the tests, placing a wire on the main 7buzz bars to replicate several of the OE events. And 8 we are also looking at changing the configuration of 9 the design of the switchgear, basically the horizontal 10racking versus the vertical racking design of the 11breakers to assess the impact of the volume and the 12configuration difference between those two. And I 13 believe this has been added in the 2020 test plan.
14MR. MELLY: Yes, I will have a slide kind 15 of detailing what that looks like in terms of our test 16 matrix.17MR. RANDELOVIC: So, if we have sufficient 18data from OECD testing, we will be testing with two 19 different configurations of the switchgear design, 20 locating the wire at the different locations to 21replicate the OE. And we believe that that will 22 provide sufficient information to come up with a model 23 that replicates the operating experience.
24MR. MELLY: Yes. And one important thing 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 71 to note, also, is that we are trying to maintain that 1 1-to-1 parameter investigation as part of this test 2 plan, so we can really investigate the differences in 3 the damage or in the differences in the data by only 4 varying one parameter.
5 So, as we talk about testing on the supply 6 side configuration, as it where here, we're going to 7 be doing the supply side -- we're going to be doing 8 the decrement curves also in the supply side 9 configuration, so that we can compare them as we move 10 forward.11And this is also one area where the 12 Working Group is actively improving the way that we 13will be conducting the test.
If we go back to the 14 slide, that blue arrow, at the last Working Group, in 15 terms of understanding how the power is going to be 16 flowing through the cabinet, may change depending on 17Working Group recommendations. We will be still 18 initiating the arc in the supply side configuration.
19 However, we are currently discussing options to best 20 reflect the realism of what that cabinet will look 21 like when it is arced and how it will relate to 22 operating experience, and how it will arc actually in 23a real plant.
So, that is one area where we are 24 currently still hammering out the details of where 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 72 we're going to be initiating the arc and what that 1 cabinet will look like in the KEMA test facility.
2 So, as we discussed previously, one of the 3important aspects of this is frequency. As part of 4 this Working Group, we're looking at all the OpE.
5 We're evaluating the energy arcing fault frequency as 6well. We will be coming up with new frequency values 7 apart from those in 2169, NUREG-2169 currently.
8 Our main focus here is that we're going to 9 be looking -- we're trying to understand the high 10 energy arcing faults events that have occurred and 11 what we're calling high energy arcing fault events as 12we move forward. There is some clear distinction 13 there that we -- on the screen here you see Arc Fault 14 Class 1, Arc Fault Class 2, and Arc Fault Class 3.
15 That is trying to get in to count the difference 16 between what we're calling arc flash, arc blast, and 17 HEAF.18 The arc flash event is typically things 19 that are going to be captured in the Bin 15 electrical 20 fire bin, because these are where arc fault protection 21schemes work. These are cycle-type events, 22millisecond-type events. These are not the high 23energy arcing faults. It's a quick pop; the event is 24 over. We don't have a sustained arc.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 73 In the arc blast event, we do see that 1 there might be a slightly extended duration, on the 2 order of 30-40 cycles, typically less than a second in 3 duration, and there's no ensuing fire after this 4event. That is one important distinction to make with 5 the arc blast and what distinguishes that from the 6 high energy arcing fault events.
7 These high energy arcing fault events, 8 Class 3 are what are going to make up the Bin 16.1, 9.2, .A., .B frequency and how we're going to relate 10the modeling. There may be some end-states in our 11 trees that we showed previously to look at the blast.
12 However, it will have a unique modeling approach to 13 basically show that there is not an ensuing fire 14 associated with these events.
15 The classic event that we could use an 16 example for that case is the event that occurred in 17 2017 at Turkey Point. We did see that we had an arc 18fault. We see pictures of it here on the screen. It 19was, roughly, a half-second event. We saw some 20 pressure damage over here on the right. That is the 21door from Turkey Point. However, there was no ensuing 22 fire associated with that event. The question 23 becomes, is that a HEAF? How do we deal with that?
24 We don't want to model this huge, ensuing 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 74 fire event, a rapid ignition, hot gas layer-type 1concerns, if that's not what the OpE is showing us.
2 So, the Working Group is actively taking these into 3consideration, so that the frequency is a true 4 reflection of how we will model it in terms of 5 scenario modeling.
6 Just visually, you can see the depiction 7 of these, the differences in the fault classes on the 8 screen from the quick, pop-type event where we're 9 going to blow a panel open; we'll see some scorching 10 versus, potentially, the arc glasses one level up, we 11 see some potential pressure increase damage, versus 12 what classically would be defined as HEAF large damage 13 state; could be potential pressure questions as well, 14 and this zone of influence.
15 One important distinction that I don't 16 think we've been discussing is we're not just looking 17at electrical cabinets. We are also dealing with the 18 bus ducts as well as the bus duct enclosures, and the 19 impact that those can have on high energy arcing 20 faults.21 So, the Working Group's charter is both 22 electrical enclosures, low voltage, medium voltage, 23and the bus ducts. This upcoming test series does 24 have five tests on bus ducts in various 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 75 configurations.
1 Marko, anything to add on that?
2 MR. RANDELOVIC: Next slide.
3 MR. MELLY: Next slide.
4MR. RANDELOVIC: What we currently have in 5 the 6850 is 3x3x5. Take that zone of influence, and 6 you are applying to it every single switchgear in the 7plant. No matter what kind of protection you have, 8 you are still applying zone of event, zone of 9 influence, in every single switchgear.
10 So, what we have been doing, we have been 11reviewing 150 power plants. We wrote a white paper on 12 this, and we grouped eight different designs, as we 13 explained already several times, how susceptible they 14 are to the long-duration faults and what would be the 15 response to HEAFs, based on in which zone those HEAFs 16 occur.17 In addition to reviewing and incorporating 18 into more the plant design, as I said, we are also 19 incorporating the insights from the OE and how we are 20 going to split fractions, loads versus breaker, lead 21versus supply. And then, as I said, you know, we have 22 the majority of those events occurring at the breaker 23step. So, we will still have to divide and split 24 additional, have additional split fractions in our 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 76 event trees.
1 So, this is definitely moving away from 2one-size-fits-all. It does incorporate the OE 3 insights and credits the protection scheme directly in 4 the event trees.
5MR. MELLY: Yes, and we also took the 6operating experience. In our last Working Group 7 meeting, we went through every single event and tried 8to link it with one of these zones. Where in the 9plant did it occur? Which zone can we call that? And 10 how does that allow us to investigate the event?
11 Also, this picture on the screen is just 12 we're using it for visualization purposes. It's not 13every plant. We have different pictures for 14 potentially different plants and different designs.
15You can flip to 1E versus non-1E in some cases. Some 16plants will have a generator circuit breaker. This is 17 just used as an example of how we're going to present 18 the information in our report.
19 MR. RANDELOVIC: So, if you have a HEAF, 20 this, the Class 1 and switchgear, you have one, two, 21 three, four breakers that are currently not credited.
22 We're just using the zone of influence, some zone of 23 influence, in doing the zone of influence in the PRA 24 model.25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 77 Now the more breakers you have, of course, 1 the less likelihood of having a long-duration HEAF 2there is. And that's going to be reflected if you go 3 to the next slide.
4MR. MELLY: Yes, and we can see on -- can 5we go back one second? We can see on this slide that 6 we can now identify in your plant where you might have 7 a susceptibility to having these long-duration, 8generator-fed events based on your plant design. And 9 we're going to allow the modeling to show that.
10 Next slide.
11MR. RANDELOVIC:
And so, this is an 12example event tree. Basically, it's exactly the same 13as the long-event PRA. You have an event and you are 14 modeling your protection scheme throughout the fault 15 trees.16 And here, the end-state will be the 17 duration of the HEAF. And you can see in this fault 18 tree that you are creating different breakers in your 19 protection scheme to reflect the duration of the zone 20 of influence of the HEAF, depending where you are in 21 the design of the plant.
22 How we are incorporating here the 23 operating experience, for example, here you have 24supply and load. We are seeing that 80 percent of the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 78 HEAFs occurred in supply, and only 20 percent occurred 1on the load configuration. So, this is a complete 2 integration of the operating experience and plant 3 side.4 MR. MELLY: Yes, and also, we have shown 5 here -- we haven't shown the values that we're going 6 to be putting in here, and these duration values that 7 we have currently on this table are only placeholders.
8They're "for example" purposes only. We've not 9 actually done the work to decide which durations will 10 link with what part of your plant in your in, and 11 then, the zone of influence, what will be affected.
12This is all preliminary. We're just making sure that 13 we have the structure in place, so that we can 14 incorporate unique plant design.
15MR. RANDELOVIC: So, the testing is going 16to come into play here. The testing is going to 17inform those numbers. So, we would have a table with 18 the zone of influence for copper and for the zone of 19influence for aluminum. Because we will be testing 20 two different switchgear designs, vertical versus 21 horizontal, we may even have a further split for data 22 for the zone of influence to see if there is any 23 difference.
24MR. MELLY: And I will note that we've 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 79 discussed that the Working Group is actively working 1on these types of things. At our first Working Group 2 meeting, we had a version of that preliminary table 3 that we just showed, and it completely changed on the 4second Working Group meeting. And we feel like it is 5now more robust. But when we do have further Working 6 Group meetings, I do expect that we're going to make 7 tweaks to that table and that structure in order to 8 make sure that we adequately have enough hooks in the 9 model to capture all the unique plant aspects.
10All right. Now what we have on the screen 11 here is kind of the overview of our measurement 12 techniques, so what we will be measuring in this 13upcoming test series. We're going to be looking at 14 the temperature and heat flux at multiple distances 15 away from the arc location. We are hoping that that 16 will aid in the dynamic zone of influence creation as 17 well as some of the modeling approaches that we will 18hear about later today. And the hope is that that can 19 link to some of the planned work at Sandia in terms of 20 the fragility and the criteria testing that we will, 21 again, discuss in the afternoon.
22 We're also going to be measuring pressure 23internal to the cabinet. What's mentioned here is 24that it's improved measurement techniques. We are now 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 80 using the fiber optic cables in this phase 2 testing.
1 We're seeing a lot less noise and a lot more pure 2 pressure measurements from internal to the cabinet.
3 And as a Working Group, we're looking at 4 the potential to measure the impact on room pressure, 5 how the internal cabinet pressure could, then, feed to 6 potential overpressurization of a larger space in 7terms of an electrical enclosure room, a switchgear 8 room, like we saw at the Turkey Point event.
9 We're looking at the damage zone, both 10 visually as well as the furthest extent of damage that 11 we saw, both the thermal, the fire damage and smoke, 12and the physical, if we throw any cabinet doors or 13 have shrapnel, in terms of effects like those.
14 We will also be measuring conductivity, 15 which we'll be discussing in a few more slides greater 16 detail, using Sandia measurement techniques as well as 17other options. And we'll go into a little bit more 18 detail of what we mean in terms of how we're measuring 19 that conductivity.
20 As part of the first test series, we saw 21 that aluminum did short out some of the KEMA 22components and their incoming power supply. That was 23a surprise to us in the first series of testing. So, 24 we have given a lot of additional effort in this phase 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 81 2 testing program to try to understand what, if any, 1 the smoke impacts have on conductivity in terms of 2 surface deposition, as well as potential arc or the 3 breakdowns for it to bear in terms of creating a 4 secondary arc in a secondary power supply component 5within the room. We will discuss how we're looking at 6 that, and there are some pros and cons to some of the 7 methodologies.
8 Next slide.
9MR. RANDELOVIC: We're getting the 10conductivity. We just need to acknowledge that there 11 was no OE event.
12 MR. MELLY: Yes.
13MR. RANDELOVIC: There was no operating 14 event where we actually saw the combustion cloud 15 causing a flashover.
16 MR. MELLY: Yes.
17MR. RANDELOVIC: So, this investigation is 18 only because of the KEMA event, right?
19MR. MELLY: Yes. The KEMA event and, 20 anecdotally, some questions that were raised from some 21 of the foreign OpE in terms of the event that occurred 22at Onagawa. It was postulated that there were two 23 arcs, and it's unclear whether it was the same power 24supply that had the two arcs. So, we're looking into 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 82 that to try to assess whether we actually can induce 1 an arc from this cloud of aluminum. We haven't seen 2 it in OpE right now, but it is a question that has 3 been raised.
4 Also, one of the things that we did not 5 bring up on this slide is we are also going to be 6measuring EMI effects. Again, we've seen no failures 7from HEAF OpE in terms of EMI effects. However, it 8 was a question that was raised from the NRC research 9 staff and DEE, that if we will be performing these 10 high energy arcing fault tests, it would be a shame 11not to collect relevant EMI data. So, we will be 12adding probes to collect relevant data. However, the 13 current plan for the Working Group is we have no 14 action item to incorporate that into any PRA damage 15 models for HEAF unless we see surprising or unexpected 16 results from those measurements.
17 We're also going to be looking at the mass 18 of the vaporized material in terms of how much 19aluminum is vaporized during the test, trying to 20 correlate that to the duration of the event itself, as 21 well as some potential chemical energy release values.
22 That's going to be linked with the validation of some 23 of the computer models as well as the theory equations 24 for the vaporized material, as well as trying to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 83 evaluate the approximate energy release, the total 1 energy release from the high energy arcing fault as a 2 subset of the electrical energy inputted as well as 3 some of the chemical energy from the oxidation of 4 aluminum.5 We have cable sample materials put in 6place on our test stands. We're also going to be 7 looking at some of the byproduct in terms of 8conductivity as well. We're going to be using some 9carbon tape, and we used aerogel in 2018. For the 10 2019, we're going to be still using the carbon tape as 11 well as a silicon/quartz-type measurement device, 12 simple because the carbon tape did give us good 13 results; the aerogel is a robust material. However, 14 we found that the carbon tape gave us enough or 15 adequate information, so we didn't need to add the 16aerogels. And the carbon -- or the silicon/quartz 17 I'll get to in a further slide, as to what exactly 18 we're looking at in terms of why that's been added.
19 Again, this is trying to answer the 20 question of what is potential conductivity on that 21 aluminum that could be potentially deposited on 22surfaces. So, we see this white cloud being deposited 23 on equipment or on adjacent walls, and we're trying to 24 understand what effect that could have for electrical 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 84 components.
1 Some of the preliminary information is 2 that the material further away from the test sample, 3that deposited material is all aluminum oxide. And if 4 that is the case, then, hopefully, this test device 5 will answer the question final, whether that even is 6a concern. If it's aluminum oxide and non-conductive, 7 it may not cause failure on adjacent components from 8 the deposition, and we will have the answer as to 9 whether it needs to be incorporated into the PRA 10 failure model.
11 Again, we will not measuring the heat 12 release rate in this phase 2 of testing, based on the 13 lesson learned in phase 1.
14 Next slide.
15 So, in terms of the surface conductivity 16 measurements, we do have fairly good experience with 17this type of measurement. It's a passive measurement.
18 We're going to be taking interdigitated resistivity 19 measurement structures, essentially, looking at what 20 the resistance on this material is prior to the test, 21 and then, what the resistance is after the test, when 22we have deposited aluminum or aluminum oxide or 23byproducts on this surface. It will help us evaluate 24 any impact of the deposition of material in terms of 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 85 electrical failure. We'll get into some of the pros 1 and cons of that in a later slide.
2MR. RANDELOVIC: So, I would like just to 3 explain a little bit the issue with this measurement.
4 So, this idea was brought to the Working Group maybe 5 three weeks ago.
6 MR. MELLY: Yes.
7MR. RANDELOVIC: And so, the Working Group 8 members have been asking how the data that is going to 9 be collected is going to be used for the PRA model.
10 So, how do we ensure that we collect the data that is 11 prototypical to the plant conditions, actual plant 12conditions? I think the NRC has an action item to 13 provide that information to the Working Group, so that 14 we can determine if this is a valid approach for the 15 conductivity measurement.
16MR. MELLY: Yes, and that's an active, 17ongoing Working Group action item. I believe Gabe has 18taken the lead on that one. If he wasn't sitting 19 here, that's what he would be doing upstairs.
20 So, again, we're trying to get to the 21 potential for failure of electronic equipment if it is 22 exposed to the arc ejecta through this type of device.
23 Next slide.
24 We're also trying to take a more active 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 86 measurement of the conductivity using a Sandia product 1as well. This is a mesh design. We have a mesh 2 design on these air conductivity measurements for the 3 EMI rejection. This is not the device that is going 4to be measuring EMI. This is more looking at the 5 conductivity of the air itself during the test.
6 Again, this is a more recent development in terms of 7 testing parameters, and it is, again, an action item 8 of the Working Group to evaluate how the measurement 9 that we will be receiving will relate to the 10 functional failure or potential functional failure of 11 components within actual plant design.
12 Next slide.
13 And we're going to be discussing these, I 14 believe, later in terms of modeling, and we have 15 additional backup slides going into pretty good detail 16 on what these devices are and how they are going to be 17 used.18 One of the other main aspects that Marko 19 is going to cover is this flashover concern in terms 20 of, can we induce an arc in a secondary piece of 21 equipment? Marko, do you want to discuss this?
22MR. RANDELOVIC: So, following 2018 23 testing and before the January meeting with the 24Working Group, EPRI has been raising some concerns 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 87 regarding the conductivity measurement, and especially 1 the static conductivity measurement.
2 So, for the January meeting with the 3 Working Group, we took an action on the EPRI side to 4 come up with a concept that could be used to measure 5 the flashover that would be more prototypical to what 6you would expect in the plant. We brought the concept 7 to the Working Group in January, and the Working Group 8 really liked the concept.
9 So, what EPRI did, we came back from the 10 Working Group and spent some time designing a mock 11 switchgear test unit that, basically, preserves some 12 specific characteristics of the switchgear in the 13 plant, given the restrictions that it has to be small; 14 it can be powered by KEMA, and we can't use the DAC 15 from Sandia.
16 So, we came up with the design, a detailed 17 design, of the mock switchgear test unit that, as I 18 said, represents a typical switchgear with respect to 19 voltage, bus bar spacing, and standoff insulators to 20ground. It's portable, reusable, and doesn't require 21 excessive power.
22 We have brought this to the Working Group, 23 once we finalized the design, and the Working Group 24really liked the concept. It has been verified by 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 88 NRC's electrical experts, EPRI's electrical experts.
1 However, we have not brought this concept to the 2 switchgear manufacturer to really have the last checks 3 to ensure that, you know, this type of test equipment 4 would actually replicate really the flashover in the 5 switchgear.
6MR. MELLY: Right, and this was one of the 7 pieces that the Working Group did discuss in our last 8 meeting in March. And it was a benefit to have this 9type of equipment. It was found out last week that we 10 wouldn't actually have or EPRI couldn't provide this 11piece of equipment for the upcoming test series.
12 However, we have tried to work with Sandia in order to 13 get data that is active data, rather than a binary 14 bounding result of, yes-no, we have flashover, in 15 terms of trying to answer this type of question with 16 the air breakdown strength, another active measurement 17 device that we're going to be putting in the test 18 cell.19 So, while this unit will not be in this 20 upcoming test series, Sandia is confident that we can 21 get relevant data to inform this flashover effect, and 22 we're actively sharing that information with the 23Working Group. Again, this is the last week's 24 discussion, that this would not be coming to the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 89 upcoming tests due to the last step not being 1 performed on verification with switchgear 2 manufacturers or funding issues.
3MR. RANDELOVIC: Funding and, also, the 4 tests are in August.
5 MR. MELLY: Yes.
6MR. RANDELOVIC: So, it takes eight weeks 7 to manufacture those components.
8 MR. MELLY: Right.
9MR. RANDELOVIC: DCI, I have been 10 discussing it with DCI. It takes about eight weeks.
11 MR. MELLY: Yes.
12MR. RANDELOVIC: First, given that we 13 started to design it in February-March, and it took 14 some time to actually collect all that information and 15 come up with some kind of design, while the last step 16 was not performed, but, then, the problem is, you 17 know, if the test is in August, even if they performed 18 the last check, and even if they want to buy the 19 equipment, it takes about eight weeks to even deliver 20 this test equipment.
21MR. MELLY: Right. So, we have identified 22an alternative to answer this flashover question. We 23 shared it last week with the Working Group. This is 24 a device we currently have available from Sandia, and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 90 we believe it is now linked, our alternative is linked 1with a standard. It's slightly altered to facilitate 2 the test environment that we're going to be in, and it 3 will answer, hopefully, the same question as this mock 4 switchgear box with more data that we can post-5 processing use.
6 Again, active area of discussion with the 7Working Group. We just presented it last week. We're 8 working on this test plan.
9 Do we have additional slides to that 10 effect? Hold off, yes. And we will have additional 11 slides as to our alternative to this mock switchgear 12 in the afternoon.
13 MR. STONE: Hi. This is Jeff Stone from 14 Exelon. A quick question.
15 Are you designing any of this test to see 16 if there are potentials to reduce the scope of this 17review? For example, if you find that medium or small 18 or low-voltage cabinets don't have a large difference 19 in zone of influence for aluminum versus a non-20 aluminum breaker, to try to limit the scope that we're 21 working on, or are we just going to continue forward?
22MR. MELLY: There is no current plan to 23 reduce the scope because the test matrix is designed 24as the minimum number of tests that we needed to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 91 answer the question. Now, if we see a huge -- if we 1 see something different as we start running these low-2 voltage tests, and we do not see a damage shape at 3 all, it could inform potentially future testing, as 4not part of the GI. But in terms of reducing the 5scope, I would say not for the pieces of equipment 6 because we're only testing five bus ducts and four 7 low-voltage equipment, and then, four additional tests 8on medium-voltage equipment. So, there's not very 9 much room to reduce the scope.
10 However, if we're talking about actively 11learning from our results, I would say yes. For 12 instance, if we see that we do not have any impact 13 from this switchgear test unit or the holdoff strength 14 in open air, we might be done with doing that test.
15 We've evaluated that it has no impact, and we don't 16 need to perform additional tests.
17 On the other hand, if we see that we see 18 this huge impact on open air, we're now investigating 19 putting our device inside an electrical enclosure or 20 inside a box, so we can limit the open air and get 21 more close to realism.
22 MR. STONE: So, you have high confidence 23 that aluminum is going to make a dramatic difference 24 in low- and medium-voltage cabinets right now?
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 92MR. MELLY: Based on our current 1 understanding from phase 1 of tests, I would say yes.
2 The low-voltage tests that were performed in phase 1 3 on copper, it was my thought that I could drastically 4 reduce the zone of influence, based on the fact that 5it was low voltage. However, one of the last tests 6 that we ran, the low-voltage piece of gear with 7 aluminum in it had a much larger zone of influence 8than we anticipated. So, it's still an unknown at 9 this point.
10MR. STONE: Was it larger than the copper?
11 MR. MELLY: Yes.
12 MR. STONE: Thank you.
13MR. TAYLOR: I think just one point to add 14to that. We don't know at this point how big of an 15 increase the hazard would be with aluminum versus 16 copper. And the second piece of that, even if it is 17 an increase to the hazard, we still don't know how big 18of an increase on the risk it has. So, that's all 19 things and actions that have to be done as part of the 20 GI program to really assess the risk impact on the 21 plants before it would move forward to the regulatory 22 stage or it gets kicked out of the GI program, and it 23 gets resolved in an update to fire PRA guidance.
24 MR. HAMBURGER: In terms of the question 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 93about high confidence that there is a difference 1 between aluminum and copper in low-voltage gear, we're 2conducting four low-voltage tests with aluminum. So, 3 just in terms of minimum number of tests to 4 investigate that question, I think we're probably in 5 the realm of a reasonable number of tests to answer 6 that question of is there a difference.
7MR. RISHEL: A question. Bob Rishel from 8 Duke Energy.
9 Just on the test configuration and the OE 10 that is informing that, I just question, what does the 11short construction look like? Are we trying to 12 replicate foreign material being captured in the 13cabinet and that's causing shorts? Or are we assuming 14bus bars come loose and form a hard contact? So, what 15 is the short we're trying to replicate?
16 MR. MELLY: So, it would be any and all.
17 From, basically, the OpE, we've seen that you can have 18foreign material enter the cabinet. We've seen fallen 19pieces of conductive material within the cabinet. We 20see breakdown at the breaker itself. We see high-21resistance contacts initiating an arc. The OE is 22 trying to reflect the frequency that is making up Bin 23 16, which includes all of that.
24 Now, in the testing space, we are 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 94 initiating the arc using a three-phase connection 1associated with the IEEE standard. So, it's a copper-2 aluminum wire, copper-tin wire that is placed between 3the three phases of power to initiate the arc. It, 4 essentially, provides the initial ionized material to 5 create the arc in the cabinet, which, then, initiates 6the arc. And whether it has enough energy to persist 7 is dictated by the power supply.
8MR. RISHEL: So, we're going to take that 9 data and we're going to try to translate that into a 10 zone of influence for that. And actually, it's that 11 specific configuration or it's that specific amount of 12energy, right? Each high energy arc fault has a 13 unique footprint, and it is based upon how much energy 14 can be released before the event is terminated, either 15 through relaying or just the material is consumed.
16 MR. MELLY: Uh-hum.
17MR. RISHEL: And so, I've got a lot of 18 concern over how that testing is, with one standard 19 configuration, how that's going to be propagated 20 throughout all other possibilities, and especially if 21 you take the arc flashover. So, that depends on how 22 much aluminum you want to throw up in the air. I 23 mean, worst case, you could make an aluminum smelter 24and put a lot of aluminum in the air. And you're 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 95 probably going to get some kind of effect out of that 1 versus, you know, something much less significant, 2 which my guess is -- we haven't seen any of the specs 3from EMI or arc flashover. So, I would guess, from a 4 thoroughness, you're investigating it, but I'm not 5 sure what value it is at the end of the day to the 6industry. But I am concerned about the test setup and 7 how we're going to propagate that to be generically 8 applied.9MR. HAMBURGER: Okay. I think some of 10 that will, hopefully, be addressed when we discuss the 11 modeling approaches, but your point is noted.
12MR. RANDELOVIC: Okay. I think we can go 13 to the next slide.
14 MR. MELLY: We can go to the next slide.
15MR. RANDELOVIC: It's the limitations 16 of --17 MR. MELLY: Yes, and so, this is some of 18 the pros and cons in terms of the conductivity 19 measurements. In terms of the surface conductivity, 20 it is a known measurement technique. It can measure 21 the holdoff, breakdown, in addition to the surface 22 resistance. The limitation, it is a passive design.
23We can only test it after, not actively during the 24test. It does not measure air conductivity, and this 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 96 does require failure criteria of components, which 1 will potentially require additional testing or 2 engineering judgment.
3 And what I mean by that is, if I say that 4 I have a breakdown strength or a surface resistance of 5"X" amount, how does that link with whether I have a 6failure criteria of a component within my plant? So, 7 that is a limitation of that type of surface 8 measurement that we'll be conducting.
9 The air conductivity measurement probes, 10they are an active instrumentation device. So we will 11know what's going on during the arc itself. The 12 limitation is we can only deploy a limited number in 13 various locations throughout the test environment.
14MR. RANDELOVIC: It would also require 15 some kind of scaling analysis --
16 MR. MELLY: Yes.
17MR. RANDELOVIC: -- to come up with the 18 criteria specific to the actual plant equipment.
19 MR. MELLY: Yes.
20MR. RANDELOVIC: So, I would take the 21 third bullet from the first one and add that bullet to 22 the second item.
23 MR. MELLY: Yes.
24MR. RANDELOVIC: It still requires some 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 97 kind of data manipulation or scaling analysis to take 1 the data from the measurement data and understand how 2to apply that data to the actual equipment. For now, 3 we don't have that answer yet.
4MR. MELLY: Yes. The mock switchgear, it 5 is a close simulation of plant equipment, or it was 6designed to be. It has not been verified, as was 7 mentioned, yet with switchgear manufacturers.
8 The limitation is that it was a bounding 9result. It is a yes-or-no answer, binary. Do we see 10 arcing; do we not see arcing?
11 Some of the devices that we will be 12 discussing in terms of air breakdown will provide more 13 of an active measurement that we can make evaluations 14on, depending on which system you were in. We'll 15 discuss that later.
16 Next slide.
17 So, the phase 2 tests that we're going to 18 be performing in the August timeframe, September of 19 this year, are listed here on the screen as our test 20 matrix. We will be performing the 480-volt aluminum 21 bus bar tests.
22And on this screen we show 15 kA. This 23came out of the April 2018 Working Group. This value 24 has been adjusted to 13.5, based on the Working Group 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 98assessment and looking at plant design. So, we're 1 going to be testing at the 13.5 kV, or kA, at 2 2seconds and 8 seconds. And we'll be testing at the 25 3kA setpoint for 2 seconds and 8 seconds as well.
4 Again, the 25 kA there will potentially inform any 5 failure of protection, but, more likely, it will 6 represent some extrapolation to medium voltage, which 7 will be the Working Group activity to see if it's even 8 applicable to do that extrapolation.
9 Next slide.
10 Additionally, we will be doing the bus 11duct testing. This is going to be performed at 4160, 1225 kA. We have our duration parameters varied from 2 13 to 4 seconds, and we're going to be varying here the 14material properties more so. We're going to have 15 copper bus with an aluminum rounded enclosure, 16 aluminum bus with a steel enclosure, and aluminum bus 17 with an aluminum enclosure.
18 All of these configurations have been seen 19 present as part of that NEI survey, and they are out 20there in the plants. So, we want to understand the 21 differences in the energy release in terms of where 22that aluminum is. Is it in the buswork, in the 23 enclosure, both, or neither, would be part of the OECD 24 testing.25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 99 Next slide.
1 So, as part of this test plan 2 reevaluation, we are using new information when it 3 becomes available to identify and reevaluate the 4objectives of the test plan. Some of the changes that 5 have been proposed, and that we are taking into 6 account as we move forward for those September tests, 7 are the arc location, as well as the equipment design.
8 Those are the tests in the spring 2020.
9 We're going to be taking into account the 10 decrement curves and incorporating some of this 11 generator-fed aspect into the testing to understand, 12 if there is an 8-second test that is generator-fed on 13 the decrement, what is the reduced amount of energy 14 that is seen in the test environment as the generator 15 spins down?
16 Also, we have been evaluating the arc 17current. Do we see enough of a difference in that 18 parameter or can we reduce the variation in arc 19 current, so we can test more important or, as deemed 20more important by the Working Group, parameters of 21interest? So, these are all things that are being 22 discussed after and during the tests that are 23performed. As well as duration, we want to ensure 24 that it matches OpE.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 100 So, as part of the supplementary tests 1 that we've been calling them for spring 2020, which 2 are direct results of some of the discussions we've 3 had with the public engagement, we're looking at doing 4 the supply side configuration for both copper and 5aluminum. And as Marko mentioned, we're not only 6 talking about the vertical lift breakers, as we've 7 done in the past, but also now we're looking at the 8 potential to be horizontal, draw out the breakers.
9 Again, we have two upcoming tests planned 10 to look at the decrement curve and to look at the 11 static, as we have done in the past. So, we'll have 12 one-to-one comparisons of the ability to look at what 13 the impact of this decrement curve has on the test 14 results.15 These are the tests that are planned for 16 the spring of 2020, to answer a lot of the questions 17that have come up in these public meetings. Again, 18this is an active area for the Working Group. We are 19 taking all recommendations into account in terms of 20 procurement, test design, conditions, applicability to 21realism. We're taking that not only for these 22 upcoming 2019 tests, but also the 2020 tests.
23MR. RANDELOVIC: The last slide, as Kenny 24 was saying earlier, we are working on the project 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 101plan, basically, how these pieces fit together. It's 1a complex project. There's so many moving pieces.
2 And unless you are inside the Working Group, it's kind 3of hard to understand what is going on. So, this 4 project plan is going to capture the discussions that 5 we have at the Working Group level, but also how all 6 of these four different pieces actually fit together.
7 We're also going to have like kind of a 8 Gantt chart providing the schedule for different 9 activities.
10MR. MELLY: Yes. We've had several 11 meetings where we've tried to at a high level discuss 12 what we're going to be doing and some questions or 13concerns or comments were raised. My reaction was, I 14 wish they were just in the Working Group meeting 15 because we discussed that for three hours and had 16 back-to-back conversation. And it's something we're 17 thinking about; we're actively trying to incorporate, 18 and we hope that this project plan will allow any 19 interested party to dig into an area where they have 20 questions, concerns, or try to further their 21 understanding of what we're doing.
22MR. HAMBURGER: Okay. So, the rest of our 23morning meeting is dedicated to public comment. I 24 know we have a presentation from EPRI. Before we do 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 102 that, do we have any questions or comments about the 1 Working Group status update?
2 MR. MELLY: And also, I'd invite anyone, 3 if there is any line or multiple questions, if you 4 want to come up to the table and just use the 5 microphone at the table, feel free to do that as well, 6rather than standing in line. So, either at the 7 microphone or at the table will be fine.
8MR. FLOYD: Hello. I'm Jason Floyd, 9 Jensen Hughes.
10 It was good to see that you're going to 11 make some effort to make conductivity measurements, 12 but if we do observe an effect of conductivity, either 13 due to deposition or in the gas phase, that's going to 14 be highly dependent upon either the mass deposited or 15the aerosol concentration. I didn't notice you 16 discussing making either galvanometric measurements of 17 deposition or maybe use of some kind of galvanometric 18 observation measurements of aerosol concentrations in 19the gas. Because in an actual HEAF in a facility, at 20 those concentrations it's going to be very dependent 21 upon configuration, ventilation, actions taken by 22 plant personnel in the long term maybe to purge 23aerosols from rooms. And so, we need to have an 24 understanding of that mass, not just the effect.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 103 MR. MELLY: We are going to be hoping to 1 evaluate that in terms of the breakdowns measurement 2 device by looking at both open air and in an enclosure 3 to see the effect there.
4 In terms of the surface deposition, do we 5have further discussion on that later in the 6 afternoon, Chris?
7MS. LAFLEUR: Minor, because it was added 8 after the 30-day distribution slide.
9MR. TAYLOR: Yes, so as far as the 10 galvanometric measurement for the surface deposition, 11there weren't plans right now. We can go and look and 12 see if we can take the sample holders and take a 13 measurement of the deposits.
14 As far as the air concentrations, we'll 15 have to get back with the experts that run our 16 spectroscopy devices and our imaging equipment at 17 Sandia to see if they are able to capture that type of 18information. So, I think it's a good point and we 19 need to look into that further.
20 MR. HAMBURGER: Any other questions from 21 the room?22 (No response.)
23 No questions from the webinar.
24Okay. If you think of any, you're welcome 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 104 to ask them after EPRI presents their material.
1 Kelli, are you ready?
2 MS. VOELSING: Yes.
3 MR. HAMBURGER: Okay. Would you like to 4 come to the front or just sit at the table?
5MS. VOELSING: So, I think green means 6 it's on?7 MR. HAMBURGER: Yes.
8MS. VOELSING: Okay. First of all, my 9name is Kelli Voelsing. I'm the program Manager at 10 EPRI for the Risk and Safety Management Program, where 11 our fire PRA research activities fall.
12 Thanks for the opportunity to speak today.
13 And although there's a lot of people in the room and, 14 obviously, a lot of interest in this topic, I'm at 15 least glad that probably my comments and feedback will 16 get less interest than another person participating in 17 a public meeting in D.C. down at the Capitol today.
18 (Laughter.)
19 So, I wanted to set some context for my 20comments in this presentation. We've heard about 21 EPRI's participation in the Working Group, and Marko 22 clearly was participating in the Working Group. And 23 so, why in the public comment period does EPRI have 24 additional comments to make on the HEAF activities?
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 105 So, I'll try to provide a little context for that.
1 First of all, our participation in the 2 Working Group under the Memorandum of Understanding --
3 you know, we've clearly been commenting and 4 identifying technical issues related to NRC Research's 5plan for the next phase of testing. I am very 6 encouraged to see that there is a lot of that 7 technical interaction happening, that the information 8 is being exchanged, that updates and enhancements to 9 the test plan are being made, and that that 10 relationship and that feedback is working very well.
11 We've also served as a conduit to provide 12 industry OE and industry survey-type information to 13NRC Research to inform testing. We heard about the 14 electrical plant schematics of all the plants in the 15U.S. as well as our review of OE, and how that has 16contributed to the test plan. So, I think that's 17 pretty much been covered.
18 I will say that, to date, our engagement 19 has been commenting on the technical aspects of the 20 plan as presented to us. So, we did not participate 21in the PIRT. We did not participate in the OECD 22testing. We don't have access to any of that data.
23 EPRI was not engaged in the scoping or initial 24 planning or drafting of initial test plans for various 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 106 activities involved in the overall plan for HEAF.
1 And I think we focused a lot on the next 2 phase of testing being planned to start in late August 3 or September of this year, and we see that we still 4 have some major open issues that the Working Group is 5working on. So, they've been very focused on getting 6to resolution on those issues. And therefore, some of 7 the broader questions we have about the overall plan 8 and where we're going have not yet been part of the 9 scope of activities being resolved by the Working 10 Group. So, that is kind of what I'm hoping to focus 11 in this presentation, is some of those things that the 12 Working Group hasn't yet directly engaged on.
13 I was taking notes during the 14 presentation, and I have counted up here, you know, 15 maybe 8-10 times where we heard, "Well, that will be 16a good use of modeling." We hope the modeling will 17help with this. We're trying to take that into 18account. We're hoping to address this in the 19methodology in modeling. We're hoping some of the 20 information collected can be used with the modeling.
21 So, we're putting a lot, you know, we're kind of 22 putting a lot of faith in that, to take the data 23that's being collected and resolve the issue. And so, 24 that's kind of what my presentation here is focused 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 107 on.1 Go to the next slide.
2 I do think it's important to clarify 3EPRI's engagement in this activity. EPRI is an 4 independent, objective, not-for-profit, scientific 5organization chartered in the public interest. And 6 so, for us, clearly, our objective in engaging in the 7 work is identifying the input, the OE, the data, the 8 methods, the tools necessary to support realistic 9 evaluation of any change in nuclear plant risk related 10 to HEAFs involving aluminum. We obviously have that 11public sector mission. Obviously, for us, nuclear 12 safety is first as well.
13But we do want to be independent and 14 objective and make sure that the testing and the 15 evaluation of that potential change in risk is 16 representative of actual plant conditions and OE and 17configurations. And so, although, clearly, the NRC 18 has some process activities and timelines and other 19 criteria that they have to meet in their program 20related to the pre-GI process and other regulatory 21 processes that they may be involved or may enter into, 22 for EPRI it's about getting the right answer.
23 I put a little background information, 24 which, for this in the rooms, is going to be everybody 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 108 knows, but perhaps in the public slides this may be 1 important for the context of some of my other 2 comments. And I think you have seen most of this in 3 the previous presentation by the Working Group.
4 So, in order for us to evaluate risk to 5 nuclear safety, that risk has two pieces: frequency 6 and consequences. The frequency piece, as Marko and 7 Nick talked about, is being worked in the Working 8 Group, that parsing of the Bin 16 events to more 9 accurately reflect flashes, blasts, HEAF events, and 10 where the susceptibility in the plant exists, based on 11 electrical distribution systems, based on types of 12 components and applications.
13 That was a task under the EPRI Fire PRA 14 Research Plan, and that technical work, we've had 15meetings. The technical work is ongoing, and we're 16 making good progress in that area.
17 And then, of course, the consequences, as 18 we've talked about, we're all hoping that, coming out 19 of this activity, that you have zones of influence 20 that align with the end-states of the event trees for 21the frequency work. So, then, you can in the PRA 22 method apply whatever frequency you come up with for 23 your component with a relative zone or a related zone 24 of influence for that activity.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 109So, I'm very encouraged. I think there 1 was good alignment across everybody here that our goal 2 was to move from the one-size-fits-all modeling 3 approach to one where the frequency is informed by 4 what we know, and that those end-states align with 5representative zones of influence. So, I think we're 6 all aligned on the goals.
7 Next slide.
8Zone of influence. Very generically, the 9 volume and which plant SSCs or targets would be 10 expected to fail as a result of the event -- in this 11 case, HEAF -- I think it is important to recognize 12 that a zone of influence does not mean that we had 13 deposition on the wall or that we had bare bus bars 14that experienced damage. A zone of influence, by 15 definition, has to include an understanding of the 16fragility of potential targets. We need to know what 17 parameters influenced the failure of that target; at 18 what intensity those failures occur; how are the 19 factors to be related; what methodology turns a heat 20 rate or a flux or a peak temperature or a pressure 21into a failure? What is the model that supports that?
22 And where in the plant can these factors realistically 23be expected to exist and to cause a failure? We've 24 talked about the open space measurements versus what 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 110 a subcomponent might experience inside a cabinet.
1 So, I think in saying we've observed a 2 large zone of influence in our previous testing, we 3 need to be careful and recognize that we haven't yet 4defined the fragility of any of these components. And 5 what we observed was perhaps a deposition, but not 6 necessarily a zone of influence at this point.
7 So, with that as background, a few issues 8that I would like to address today. First, I've kind 9 of already alluded to the defining of fragility.
10 Second, clarification of the mod/sim approach or the 11 modeling approach and the quantification of the tools 12for that application. I know we're going to talk more 13 about that this afternoon.
14 We've already beat the next one to death:
15 utilizing the full range of OE to represent the 16 distribution or the probabilistic spectrum of events.
17 Availability and insights from previous test results, 18 and I won't spend time covering the conductivity and 19 EMI open issues from the phase 2 that the Working 20Group is still working on. So, this is the content of 21 the remainder of my comments.
22Okay. With respect to determination of 23 fragility and a zone of influence, to date, as we've 24 heard, the parameters for defining fragility for 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 111relevant components have yet to be defined. We 1 understand that this is a future activity of how 2 Research plans to address the HEAF issue, that they 3 will identify the parameters that relate to fragility; 4 determine the models and the relationships of how 5 those parameters are correlated to an actual failure, 6 and then, demonstrate the ability of the modeling and 7 simulation approach to produce results that both align 8 with the experimental data that's collected as well as 9 be translated into fragilities and a zone of 10 influence.
11 And as those activities are still yet to 12 be determined, a future phase of the work, we 13 understand that if that approach is not successful, 14that the backup would be to fall back on utilizing 15 more expert judgment to inform the process.
16 So, our concern with this being a future 17 activity that still I think we're all committed to, I 18 think we think it's the right thing to do, but our 19 concern is, without yet knowing whether that's going 20 to be successful, what that's going to look like, what 21 defines fragility, our concern is, what assurance do 22 we have that we're collecting the necessary 23 parameters? We think we've got the right parameters 24 of interest that are being collected, but without 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 112 defining how you're going to model the fragility, how 1 do you know that?
2 If the data being collected are the right 3 parameters of interest, it's yet to be defined what is 4 the method that will relate those measurements to a 5 fragility determination. And the collection of data 6 in open space, I think we all know, does not directly 7 relate to the value that a given parameter might be 8 experienced in a nuclear plant configuration -- so, 9 inside a cabinet, inside a conduit, behind a barrier.
10 And we need to understand how that's going to be dealt 11 with when translating the measurements collected in 12 open space into a zone of influence.
13 With respect to the modeling-simulation 14 approach, first of all, we are very encouraged that 15 everyone's committed to not using the one-size-fits-16 all approach; that we're committed to having relevant 17 zones of influence that are informed by what we know 18 about plant design; what we know about the function 19 and the location of these components in the plant and 20what we know from OE. So, that's all a good thing, 21 and we all recognize that our test budgets are not 22infinite. And so, having a modeling and simulation 23 capability that can help interpolate or extrapolate 24 between those measurements, test other configurations, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 113 is obviously, you know, would be of great benefit.
1 NRC Research and Sandia are proposing to 2 use the coupling of area and FUEGO codes to model the 3HEAF events and to find a zone of influence. Our 4 understanding, obviously, these codes have been used.
5 They've been used in nuclear weapons applications.
6 They've been used, and, of course, they have their own 7 V&V support, which justifies the physics in the code 8 and that the code is giving the expected results; and 9 that it's being compared against a variety of data; 10 and that, for the purposes for which the code was 11 designed, that it is capable of doing what it's 12 supposed to do.
13 But what we haven't yet had time to work 14 on or have seen is the capability and qualification of 15the codes for this specific application. So, the code 16is just, you know, the math, but getting the right 17 answer is all in the model that you set up. And you 18 need to define how you're going to set up that model; 19 how you're going to do the coupling of the codes; how 20 you're going to benchmark against relevant 21 experimental data for this particular approach, and 22 prove that what you're modeling is providing you 23 reasonable answers.
24 So, we haven't had time to do that work 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 114yet. To a certain extent, we already have a lot of 1 data available or, presumably, there should be a lot 2of data available. The OECD testing was completed 3several years ago. Phase 1 testing on medium-voltage 4 equipment was completed last year in September. And 5 so, if we had the modeling and simulation approach 6 better defined, we would be able to compare that to 7the test data that we already have; see how it's 8performing. Are we collecting the right inputs? Are 9we getting the expected outputs? Do we know how to 10 translate that into a zone of influence or fragility?
11 And based on that analysis, do we need to make any 12 tweaks to what we're collecting or what we're doing in 13 the phase 2 testing?
14 And again, I think we all think the 15modeling and simulation approach would be a huge 16benefit. Definitely having different zones of 17 influence for different locations and different 18 applications is much more realistic in terms of our 19PRA modeling. But we've said, well, if it's 20 unsuccessful, then we can fall back on expert judgment 21 or test data.
22 And our concern there is, if you don't 23 have the modeling and simulation approach to 24 interpolate between 4 seconds and 8 seconds, or 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 115 between 5 feet and 10 feet, or between this type of 1 enclosure and that type of enclosure, then perhaps we 2 needed to have different targets in the test field for 3 the phase 2 testing to collect different relevant 4 measurements that would be more representative of in 5 situ plant equipment.
6 Realistic use of OE and data. You know, 7 I am very encouraged by the discussion in the room, 8 and I very much thank NRC Research and the Working 9Group for taking the feedback on this activity. It's 10 obvious that you've heard the message.
11 So, I think we all understand that testing 12 is not infinite and that it is expensive; and that if 13-- I don't know -- if the large majority of time all 14 you get is a spark, and then, the event terminates, 15 well, testing that doesn't really give you any 16 experimental data because you didn't have an arc fault 17to collect any data. So, we absolutely understand 18 that.19 But the recognition that testing outliers 20 or bounding configurations does not represent the most 21 probable event or the distribution of the event in the 22 plant, I think is a concern from the stakeholders 23because of some past experience. And so, I think 24 that's why we're asking for better understanding of 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 116 how the mod/sim, how the calculation or the definition 1 of fragility and the calculation of that zone of 2 influence, the translation from measured parameters 3 into that zone of influence -- having more detail 4about exactly how that's going to work and what the 5 preliminary results we have, what are the insights we 6 have based on the testing we've already done, having 7 more detail about that would help to reduce 8uncertainty about how we're going to approach it. And 9 that would probably alleviate the concerns about 10 taking a very bounding configuration and applying that 11 all over the PRA.
12 And finally, on the availability of the 13 results, we do have not a lot of data from the tests 14 that have already been conducted more than a year ago.
15 So, some results from the phase 1 testing are not yet 16 available. We understand that, apparently, detailed 17analysis and data scrubbing is required. We have some 18 descriptions of the small-scale testing, and we 19 understand that they weren't intended to be 20 representative of a HEAF, that Sandia needs to build 21 up piece by piece to the full-scale, large HEAF 22condition. But where we are with that small-scale 23 testing is not yet representative of a HEAF in terms 24 of the geometries and the arc, arc lengths, and other 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 117 factors.1 And then, we only have very limited 2 material characterization from the small-scale 3 testing, as Nick alluded to, but our understanding is 4 that the majority of the ejecta that was measured thus 5 far was either aluminum oxide or molten metal with an 6 aluminum oxide kind of coating, which would be an 7insulative and non-conductive material. So, 8 understanding whether that's the actual condition in 9 the cloud would be important to knowing whether this 10 conductivity and flashover is really an event that we 11 need to be concerned about, since we haven't really 12 seen that in OE, and the bare bus bars on the wall 13 damage at KEMA is probably not representative of any 14condition that exists in a nuclear plant. We don't 15 have bare, uninsulated bus bars exposed in such a 16 manner.17 So, I guess, just from a project 18 management, not a nuclear risk, but from a project 19 risk perspective, the question is, is it prudent to 20 understand the insights and the utility from previous 21 data prior to proceeding with additional testing? I 22 think it's a broader concern that we want to make sure 23 that, before we spend more money and charge forward 24with more testing, that we've really evaluated the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 118 data that we have from previous results, defined how 1 we're trying to use that with the modeling and 2simulation approach. And are we getting results that 3 we think we can use or do we need to make tweaks to 4 the plan?5 Phase 2 testing, they already talked about 6 that at length. We talked about that before or that 7 the Working Group is still working to resolve the 8 conductivity issues, and that the EMI was added very 9recently. And we don't see that in OE. So, I 10 understand it was a request from others, other 11departments within the NRC. But if there's any 12 thought that somehow that translates into a fragility 13 or a zone of influence relative to HEAF, we would like 14 to have a more detailed review of that technical 15 basis, because we have not observed that in the OE in 16 any of the international or domestic events that have 17 been reviewed.
18 So, I'll try to be quick to make sure we 19 leave time for public comment here or questions from 20 others other than me before the conclusion of the 21 meeting.22 I think the graphic there in the upper 23right corner is pretty representative. There's a lot.
24 As we've talked about, this is a complex project.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 119There are a lot of moving pieces. There's the plant-1 specific aspects of configuration and layout, presence 2 of aluminum, the frequency work that's being led under 3 the EPRI fire PRA tests, definition of fragility, 4mod/sim, test results data. All of those pieces 5 ultimately have to come together to answer the 6question. And really, I guess the overriding concern 7 is we don't want to get too far out ahead with one of 8 those roads when, ultimately, they all have to work 9 together to solve the problem and get the right 10 answer.11 So, we're just suggesting that defining 12 all of the necessary inputs and evaluating the 13 currently-available data before proceeding with 14 additional testing may be a prudent option to 15 consider.16 Any questions for me?
17MR. CHEOK: Thanks, Kelli. Good comments, 18and I think we understand it. We have been working 19 together very well as part of the whole group, but we 20 understand your comment that EPRI wasn't involved at 21 the beginning in terms of the definitions, the tests, 22and the bullets, and things like that. And so, those 23 are valid comments and we will take that into account.
24 So, I think when we are talking about 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 120 delaying the next set of tests, for example, there are 1several things that we have to consider. One of them 2is that this is a pretty generic issue. If the staff 3 or the industry had identified an issue that 4 potentially could be safety-significant -- potentially 5-- we owe it to all our stakeholders to not drag the 6 issue out and just to see if it's really a safety 7 issue or something that we all can deal with in a lot 8 of different other ways. So, that's one part of the 9 schedule.10 We have gone ahead and tried -- we have, 11 between my friend and myself, asked for an extension 12 of the current GI scheduling, so that we can 13 accommodate additional comments and industry future 14 test results, et cetera.
15 So, having said that, our next set of 16 tests, whether it's going to be spring of next year or 17 summer of next year, I hope and anticipate that it's 18 going to be the last set of tests that the NRC will be 19 carrying out in terms of the aluminum HEAF generic 20 issue. And I know, as you say, budgets are limited.
21 We need to do smart testing.
22 And you also mentioned that we have a lot 23 of "unknown unknowns," a lot of things that we, in 24 terms of the fragilities -- some of them I think we 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 121 can work out over the next six months or year.
1 However, a lot of the "unknown unknowns" will not be 2 known in the next year, and I don't think we can delay 3 a set of tests because there are "unknown unknowns".
4 I think we have to be prudent in terms of selecting 5 our parameters we have to be testing for, and then, we 6 will look at the results and parse out what is 7 important and what isn't important, and then, 8 determine from that set of data, while we are marrying 9 that with the frequencies of those particular 10 scenarios, to see if any further action is needed.
11So, I think without the August tests we 12 will not be able to further validate our models.
13 That's one set of things that I think would be 14important for us. Taking the tests that we have done 15 already are only -- for example, the facade test that 16 was done by OECD -- could skew the results simply 17 because the set of tests, as was pointed out before, 18 could be conservative. So, I think we have to be --
19 you know, we are trying to expand our database a 20little bit more to accommodate what you've been 21 seeing.22MS. VOELSING: To be clear, I wasn't 23 advocating that we should draw conclusions based on 24 only the testing that's been done. I was advocating 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 122 that we would have more confidence that we are doing 1 everything we need to do in the future testing if we 2 had taken the data that we had and evaluated how is 3 the mod/sim performing against that data or what have 4we learned from that data. And we haven't really done 5 any analysis of that data yet.
6MR. CHEOK: Thanks. Thanks for the 7 clarification.
8 So, in terms of the fragility and the zone 9 of influence, we totally agree with you that the zone 10 of influence will depend on the fragility, and the 11zone of influence is very plant-specific. And we will 12 not be able to carry out every single test to take 13into account all the different configurations. Again, 14 we will have to be smart in terms of defining what we 15 need to get.
16 So, the next set of tests should provide 17us with data that may have some obvious results. So, 18 if it shows that, hey, given this cloud of dust, for 19 example, everything gets oxidized, there is no effect.
20 Either that or you can have a test that says, hey, 21 look, given this test at 3 feet, you know, the 22 temperatures and the pressures, and everything else, 23 is so extreme that we don't think that any defined 24 fragility of equipment should matter.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 123 So, I think the next set of tests could 1also tell us what could be the scope for us. You 2 talked a lot, some --
3MS. VOELSING: We're just concerned 4 because we haven't made any of those kinds of reviews 5 or analysis based on all the work that's already been 6 done.7MR. CHEOK: Yes, and we will do that, 8right? I mean, we talk about some of the fringe 9 results, and we may not, and you're right, we may not 10 be able to relate the fringe data results, for 11example, to a fragility. And we will acknowledge 12 that, and that's absolutely correct.
13 I think, with the fringe results, we will 14 obviously use those results to define our next set of 15tests. But, without knowing what the bounding 16 conditions are, where we can illuminate things or add 17 things into the scope, our next set of tests will be 18 a lot larger than it should be.
19 Again, we will try to make available, all 20the data available as much as we can. You had 21 mentioned the fact that we are looking at some data, 22 and I think I addressed the comment earlier from 23 George.24So, we cannot just release data. We can, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 124 but we should not release data without putting context 1to it. So, we do not want people to take data and 2 come up with incorrect assumptions or incorrect 3results. I think we need to say, hey, look, let's 4 look at this data; let's put some context to this 5data. And then, if we need be, we'll release all the 6 data, but we want to put some context to the data, so 7 that this data cannot or should not be misinterpreted 8 by all parties concerned.
9MS. VOELSING: Yes, I think you heard that 10 in the previous comments.
11 MR. CHEOK: Uh-hum.
12MS. VOELSING: And you guys addressed that 13you're responding to those comments. There was a 14 request to kind of show what is the basis for -- you 15 know, this is the gap; it gets filled here; it gets 16 addressed here. This is where it's addressed in the 17program. This is what we've learned. This is what 18 still remains open. And you're working on a project 19 plan to help make that all more clear.
20 So, I absolutely understand that and 21 appreciate your response to that. I guess my only 22 question is, we seem to have not done that yet for the 23phase 1 test results that took place a year ago. So, 24 when are we going to be able to get that done?
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 125MR. CHEOK: And, you know, I guess we can 1 discuss that later also.
2 But I think Jeff is standing at the 3 microphone now. I'll turn it over to --
4MR. STONE: Yes, I just wanted to add some 5 context here from a utility perspective or from my 6perspective as a utility member. It is that I'm 7 concerned and hopeful that we don't go down the same 8 path we did with some of the fire stuff years ago, 9 where we overestimated possibly some heat release 10 rates and, then, we didn't -- and along with that, we 11had conservative fragilities. It sounds like we're 12 trying to get the right heat release rates here from 13 that.14 But if we don't understand the 15 fragilities, and then, we make conservative 16 assumptions next year because we're in a hurry to get 17 this GI resolved, then we could end up with dramatic 18 overestimation of the impact of the HEAFs, if we don't 19 understand the fragilities. So, I was not clear why 20 we didn't attempt to look more at the fragilities in 21this test set. But I would like some confidence from 22 our side that we don't step into a conservative 23 assessment of the fragilities because we don't have 24 the tests.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 126MR. MELLY: So, part of the reason why the 1 fragilities aren't explicitly included or inherently 2 included at the KEMA facility is the difficulty with 3 doing the source term data, the electrical supply, 4 with the measurement techniques that are needed in 5 order to ascertain the fragility of equipment.
6 I would need to have an electrically-7 powered cable, for instance, in the test cell and 8 evaluating the shorting performance of the cable, the 9 potential for the cable to ignite, the flux and the 10temperature inside that cable that it's exposed to, 11the source term of the HEAF. And that's just for one 12 cable which is defining one piece of fragility 13 information.
14 KEMA is an electrical test laboratory, not 15a fire test laboratory. All of that would need to be 16 designed and implemented at KEMA around the HEAF, 17 which is impractical for how the tests are run in both 18 a cost impact as well as the ability or space impact 19 to actually have that type of data married up with the 20 electrical data of the HEAF.
21 So, that's why you don't see electrically-22 powered cable trays in the test setup that we're 23running. We're trying to get the data from the source 24 term of the high energy arcing fault, and then, apply 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 127 that to fragility data, rather than do the fragility 1 at the KEMA facility.
2 The way that KEMA works is we only have on 3 day to perform the tests because we're using that test 4bay. So, if we took three days for test setup, we're 5 essentially paying for three tests, which would 6 largely balloon all the entire scope as well as cost 7 of the test program.
8MR. STONE: So, I'm unclear how we --
9 there's no other way to evaluate the fragilities or do 10tests in a realistic method for that? Because, 11 obviously, if we go conservative there, the 12 implications to us in the utilities could be pretty 13 dramatic from a cost perspective.
14MR. MELLY: So, we do not plan on going 15conservatively. That is not the current approach.
16 The plan is to marry the source term data that we are 17 collecting with the fragility data or with failure 18 criteria, but not explicitly testing it at the same 19time at the KEMA facility. We understand that if you 20 go conservative, which is the scoping analysis -- if 21 I take out everything in a particular room from a high 22 energy arcing fault, it's going to have a huge risk 23impact. Is it realistic? No. We understand that, 24and our goal is not to go conservative with the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 128 fragility data.
1MR. RANDELOVIC: So, Nick, maybe you 2 should be a little more explicit on how we are going 3to get at the fragility. Like explain we are 4 collecting the test data. The test data is going to 5 be used by --
6 MR. MELLY: I believe we have --
7MR. RANDELOVIC: We have case from Sandia.
8 MR. CHEOK: Chris, first, I just want to 9address something Jeff said. So, we will not go 10 conservative -- will not. We will engage, once we 11 have all the tests, data, and results, we will engage 12 all our stakeholders with all our data, and we will 13incorporate everything that we hear before we even 14 decide what the next steps are.
15MR. HAMBURGER: Just before Chris says 16 anything, I want to give the webinar folks a minute to 17get their questions together. If you're on the 18webinar, we currently have the lines muted. But if 19 you do have a question for us, you can either type it 20 to Tom in the chat or you can use the "raise hand" 21 feature and we can unmute your line, so you can ask 22 the question. So, I'll give you guys a minute to do 23 that, if you would like to ask a question.
24MS. LAFLEUR: Okay, thanks. I'm Chris 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 129LaFleur from Sandia National Laboratories. Sorry 1 about my voice.
2 In terms of establishing what the failure 3 criteria for something like cables would be, right, 4 and that's going to be the first focus, it's a 5 function of the temperature and heat flux, but also 6 the time that a target cable is exposed to those harsh 7conditions. And so, the reaction of the cable or the 8 response of the cable for the duration of that 9 exposure we can test separately in other facilities at 10 Sandia where we can expose an energized cable and a 11 cable that's being measured for the underjacket 12temperature. We can expose it to short-duration, 13 high-heat fluxes or high temperatures, some of our 14other facilities. And we can say, okay, "X" is the 15 temperature that that cable will fail in 2 seconds.
16"Y" is the temperature that cable would fail in 8 17seconds, right? And we can bound that based on the 18 expected duration of the HEAF events, and that's --
19 MR. STONE: Is that part of the plan?
20 MS. LAFLEUR: Yes, that is the plan that 21 we're currently formulating with the cooperation in 22 the Working Group to determine what exactly we need to 23 test, bounding in between, whatever, to determine what 24 the failure criteria for cables are.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 130MS. VOELSING: Is there a timeline for 1 that?2 MS. LAFLEUR: Yes.
3 MR. RANDELOVIC: Well, we just started.
4 MS. LAFLEUR: We're doing it, yes.
5MR. RANDELOVIC: We just started three or 6four weeks ago. We had a first phone call with Chris 7 and with Jason and Gabe. And I think we are just at 8 the beginning of a process, and I think it's going to 9 take some time to develop the methodology and the test 10 facility, the test facts --
11 MS. LAFLEUR: Yes.
12MR. RANDELOVIC: -- whatever has to be 13 done.14MS. LAFLEUR: And cables are one thing 15entirely different. The subject is other equipment in 16enclosures. You know, what criteria would be 17impacting them, right? Because the critical 18 components of those equipment are within a shield of 19sheet metal, or whatever. So, we could make some 20estimates of when that aluminum enclosure or steel 21 enclosure would be breached within a certain different 22distance of different HEAF event energies. So, that's 23 what has been --
24 MR. HAMBURGER: I'll take a comment from 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 131 Bob, and then, I think we have one question from 1 Faramarz on the webinar. We'll unmute.
2MR. RISHEL: So, I just want to caution 3 this is too important for conclusions to be drawn 4prematurely because of cost and schedule. If it takes 5 longer, it takes longer, and if it costs more, it 6costs more. And I don't think we should cut off 7 testing because it takes too long or too many days or 8the lab's not available those days. If we need to do 9 it, then we need to do it.
10 Otherwise, you know, my fear is that the 11 utilities will be left with some information that is 12 incomplete and, essentially, potentially a generic 13 issue that they're going to have to go solve with 14 additional research on their own to either fill in the 15 blanks or -- so, I would caution to make sure we spend 16 the time and money needed to address it, not let cost 17 and schedule drive the answer.
18MR. HAMBURGER: Faramarz, can you hear me?
19 MR. POURNIA: Yes, I can hear you. Just 20 so people know, that was Bob; that wasn't Faramarz, so 21 to make sure I'm clear from the comments that he's 22 made.23 But, yes, just I want to say -- Faramarz 24 Pournia for the Nuclear Operating Company -- I do 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 132appreciate NRC Research. The statement was made just 1 following Kelli's presentation that the public has 2 identified a safety concern, and the Research charter 3 is to go figure out if that's safety-significant or 4 not, and provide that feedback to the public. So, I 5 do really appreciate that, and I want to make sure I 6 emphasize that, because that kind of stuck with me.
7 I really listened to the discussion that 8 went on for a while in here. It started with George 9actually. There appears to be so many issues that are 10 on the table, and some of us have been in an 11 environment of research and economic side of the 12research. It seems, though, if we don't have concerns 13 that are addressed to the points that we should do, 14 and the extent of the testing that should be done, my 15point was, would I really the meet the statement I 16 just heard from the individual from NRC Research that 17the public has a safety concern? "Our objective is to 18 go to do clear, objective, and selective of the 19 operating plants to address the concern of the 20 public." 21 Because if I portrayed these tests not 22 reflective of what the stations are and more 23 realistic, my concern is, am I answering the public 24question in a proper way? But I may be fanning an 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 133anxiety over an issue that may not be reflective of 1 the true significance of this event.
2 So, with all that discussion that went on, 3 I think it would be understood that maybe a time of 4 doing a look-back and say, are there some anomalies in 5 here that perhaps -- to what the individual brought up 6 from NRC Research -- a clean time and go through the 7 process to make sure that we have the appropriate 8 layout to go to do this test is more warranted, rather 9 than just proceeding because you are driven by 10 schedules or other needs and ways that we just have to 11 do it.12 So, thanks for your time.
13 MR. HAMBURGER: Okay. Thank you. Thank 14 you for that comment.
15You have a written comment? Okay. Can 16 you remember it or?
17 So, there's a written question on the 18 webinar about the calibration of the models that we 19intend to use. And I'm going to ask that that person, 20 during the webinar for the afternoon, because we have 21 an entire afternoon dedicated to exactly that subject 22-- so, if you still have that question this afternoon, 23 then we will be happy to address any further 24 questions.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 134 Anyone else in the room have comments or 1 questions that they would like to make?
2 And again, if you're on the webinar, 3 please go ahead and use the "raise hand" feature or 4 the chat feature, and we can open up a line or relay 5 your question.
6 (No response.)
7 I want to remind everybody on the webinar 8 that there is a separate link and webinar session for 9the afternoon meeting. So, when we finish here for 10 the morning session, we are going to terminate the 11webinar. Please use the afternoon meeting webinar to 12join us for this afternoon's session. And that is 13 available on our public meeting website.
14 And if anybody has any questions that 15 occur to them during the afternoon session, we do have 16 another public comment period scheduled for the last 17part of the day. So, if it does come up, if it 18 strikes you while we're having our afternoon 19 discussions, you can feel free to ask any questions 20 then.21 If you haven't signed in on our sign-in 22 roster, please do that before leaving for lunch, if 23you don't mind. I'll have a new roster for the 24 afternoon meeting.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 135And got another one maybe? We maybe have 1 a webinar question.
2The afternoon session starts at 1:30. If 3 you're a visitor and you're going off-campus, I would 4suggest trying to get back to the security booth by 5 about 1:20 to make sure all get back up here in time.
6 And we'll have NRC staff helping to escort people back 7 to this room.
8 I put my number up on the display again, 9 in case anybody has any trouble getting back in.
10 Tom, anything? No? Okay.
11 All right. Well, thank you all for your 12 participation this morning and I look forward to 13 seeing you back at 1:30, if you're participating in 14 the afternoon session.
15 (Whereupon, the above-ent itled matter went 16 off the record for lunch at 12:14 p.m. and resumed at 17 1:33 p.m.)
18 MR. HAMBURGER: Okay, it's past 1:30, so 19we'll get started. Welcome back. For those of you on 20 the webinar, unless you are one of our Sandia 21 participants, we have you muted currently. If you'd 22like to say something, you can either use the raise 23 hand feature or send a chat message to Tom, who is 24 manning the webinar, and we can open up the phone 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 136 lines for you.
1 Same rules as this morning, we are 2 transcribing the session, so please state your name 3 before speaking. Please speak into the microphones, 4 and you'll need an NRC escort to go anywhere off the 5 floor and lobby level here.
6MR. TAYLOR: All right, welcome, 7everybody. My name is Dave Taylor. I'm with the 8 Office of Research here at the NRC, and this 9 presentation that I'll be going over this afternoon 10 basically provides an overview of the HEAF hazard 11 modeling.
12 So I'm going to be providing some 13 background information on how it's currently modeled 14 in the fire PRA, and then get into, when we're looking 15 at developing or improving the model, the different 16 approaches that we have or types, quickly going over 17 the instrumentation that we're using to help feed back 18 to the models and provide some form of validation to 19 the models.
20 Then I'll be going briefly over some of 21 the more popular existing models, and these are, they 22 really have been developed for arc flash hazards, 23 looking at personal protection, hazard to persons from 24 burns from an arc flash.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 137 But I'll briefly be going through some of 1 those models and then provide some comparisons to the 2 measurements that we made in the fall testing too, 3 those models, as well as I'll be talking about some 4 air voltage breakdown tests that we'll be running and 5 providing a little additional information on how that 6 information can be potentially used to confirm a model 7 that's existing that estimates the breakdown voltage 8 of air based on temperature and metal particulate 9 within the air vapor mixture.
10 So into the review of how we model it in 11 PRA, and there's really two different distinct 12 approaches when you look at electrical enclosures, how 13they're modeled. The one on the right is the thermal 14classical fire modeling that looks into, okay, you 15have a fire inside of an electrical enclosure. How 16 does that fire grow and develop in such a state that 17 it could potentially damage other equipment that is 18 important to safe shut down?
19 And then on the right side of the diagram, 20 we have the high energy arc fault failure mode, and so 21 instead of the classical thermal slowly developing 22 fire, we have a more rapid, energetic release of 23 energy, a high energy release of energy to the 24 enclosure as well as surrounding components near the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 138 defaulted enclosure.
1So the focus of the project that we're 2 underway in is looking at the high energy arcing fault 3 or the approach on the left, or, excuse me, right.
4 We did back to, you know, some of the 5 operating experience and how the methods were 6developed. There's really the key event that happened 7 back in 2001 at San Onofre Nuclear Generating Station.
8 The NRC issued an information notice after 9 that event, and basically at the time frame when this 10 event happened, the NRC and EPRI were in the 11 development of the fire PRA methodology.
12 So because of that development of that 13 method, it was a great opportunity for those writers 14 of the method to go out and see these events and 15 understand the hazard from these types of events that 16 eventually got rolled into the model that we have in 17 the 6850 document.
18 Now, if you look in 6850, it was published 19in 2005. In 2004, the NRC amended its fire protection 20 regulations to allow the use of performance-based 21 standard NFPA 805 for fire protection, and that 22 standard NFPA 805 was issued in 2001.
23 So since the Commission policy statement 24 of '95, the Agency has been moving towards a more risk 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 139 informed approach to a number of regulatory topics, 1 fire protection being one of them, so it was time to 2 have this method published, and it was developed with 3 the best available data and information at the time 4 with a joint team of experts to develop those methods.
5 So as I said earlier, they looked at that 6San Onofre event. There was also an operational 7 experience assessment report that was put together 8 that looked into energetic faults that happened from 9 1986 forward to 2001, which also provided a lot of 10 information on the type of energetic failures that 11 have occurred in the plants.
12 If we look more specifically into how it's 13 modeled, we talked a lot about the Zone of Influence 14 this morning, but basically around the initiating 15enclosure, you assume that any equipment inside a 16 three-foot horizontal or a five-foot vertical zone is 17 damaged and ignited.
18 And this was basically developed through 19 an expert solicitation process from the observed OpE.
20 There was no data that was used. However, it is the 21 model that has been accepted in a number of 22 applications that support the NFPA 805 transition.
23 So just another photo of the San's event 24from 2001. It was a fairly significant thermal event 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 140 from the duration that it took to fully suppress, but 1 also we have some international operating experience 2 from Onagawa.
3 Back in 2011, they had a HEAF that damaged 4 a series of switchgear. The event also lasted for a 5good portion of time. However, a lot of that duration 6 was due to difficulties for their fire brigade, off-7 site fire brigade, to respond to the event, but you 8 can kind of see from these photographs the extent of 9 damage to the initiating equipment and adjacent 10 electrical enclosures.
11 Subsequent to the issuance of 6850, we had 12 the Frequently Asked Question program that was 13identifying a number of questions industry and our 14 stakeholders had on the application of the method.
15 One of those was FAQ 07-0035, and the resolution of 16 that frequently asked questions document in not only 17 an enclosure memo, but in supplement one to 6850.
18 And what this guidance provided was a 19 method for modeling high energy arc faults that occur 20 in bus ducts, so you can use that information to model 21 a HEAF that has occurred or would occur in a bus duct.
22 And here we're just showing a few examples 23 on the left and right of actual OpE showing the failed 24 bus duct at Diablo Canyon as well as at Columbia, and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 141 the photograph in the center is showing you testing 1 that we did in Phase 1 of the OECD program where we 2 had a bus duct that was removed from the Zion Nuclear 3 Power Plant and tested in that program.
4 Now, the bus duct conductors themselves 5 are copper, but the enclosure is aluminum, and from 6 the observations that we've observed in the testing, 7 we saw that there was a lot of aluminum interaction 8 that created a more energetic event than we had seen 9 in other non-aluminum based experimental tests that 10 were performed.
11 So that's a quick overview of where we are 12right now. Looking at those two models, the key point 13to get there is it's one size fits all. You have a 14model for electrical enclosures, and the zone of 15 influence of three-foot, five-foot, that matches up 16whether you're in low voltage gear, medium voltage, 17 whether your available fault current is 10,000 amps or 18 30,000 amps.
19 It doesn't really get into a lot of the 20 details that really impact the amount of hazard that 21 you would deal with in the plant, so moving forward, 22 we'd like to improve what's currently being used and 23 available.
24 And one reason that, you know, I'm 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 142 presenting this information here is I think there has 1 been either miscommunication or misunderstanding from 2 some of our stakeholders that, you know, we're only 3 looking forward to working with the Sandia models and 4 developing new models.
5 At this point, we haven't made any 6decision on what's the best approach? What's the best 7 model to accurately characterize the hazard?
8 So there are a lot of arc flash models out 9there and we're looking to see if they have any 10 utility in the work that we're doing or if we can take 11 those models and make any modification to them to 12 support the hazards that we're trying to model.
13 So the next set of slides that I'll be 14 going back to, they were actually presented in an 15April 2018 public workshop providing a high level 16 approach for how we're looking into doing the 17 modeling, and we kind of break it into three different 18 categories.
19 The first category would be the bounding 20 model, which would basically be what we currently use 21in 6850 or the supplement for the bus ducts. You 22 basically have one model that captures everything.
23 You make it bounding to capture everything and you use 24 it.25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 143 Evolution from that would be where you 1 take some plant information, whether it's the amount 2 of energy, the fault protection scheme, equipment 3 configuration, safety class, material, and you can use 4that information and basically subdivide it into a 5bunch of different bins, and each bin would have a 6 different ZOI or a different hazard associated with 7 that based on the potential for the equipment and the 8 category, so that would kind of be the second category 9 class of modeling.
10 And the third one, which we retermed 11dynamic zone of influence, would basically be where 12it's plant specific. You go out and you identify what 13 your available fault currents are, what your voltages 14 are, what your, your key parameters, whether it's the 15 bus bar gap spacing, component configuration, what 16 have you.
17 You feed that into the model, and then the 18 model outputs typically an incident energy or a heat 19 flux, and then you can take that information, and with 20 the target fragility information which Sandia and I 21 will be talking about later, you can connect the two 22 dots together such that if you know you have a 23 vulnerable target in your fire PRA scenario that's X 24 feet away, you run the model and you determine that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 144 your heat flux or incident energy is Y, you know, 1kilowatts per meter squared. Then you can look at 2 your target fragility and determine whether that 3 target would have failed or not.
4 So something like that's similar to what's 5 done in some of the arc flash models, and we'll go 6 through some of those later, but those kind of lays 7 out the three different categories of modeling that 8 we're looking into.
9 We're not tied into one particular, and if 10 I had to guess, we probably have a mix of some of 11 these categories for PRA applicability and ease of 12 application of the method.
13 So just a refresher again, bounding 14 assumes worst case, one size fits all. You need the 15 least amount of information to apply it and it's 16fairly simple to apply. However, you get the least 17 realistic results for the majority of the cases, and 18the costs for the application, at least the 19application is low. The costs to your risk profile of 20 the plant might be high.
21 The second category, refined bounding ZOI, 22 this is where we subdivide the equipment into 23 different categories, whatever they may be, whether 24 it's equipment power, energy, protection schemes, so 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 145on and so forth. It provides more realism. If you've 1 followed what we've done in the heat release rate 2 realm for electrical cabinets lately, that's kind of 3 the approach that we've taken.
4 We basically better characterized the 5 combustible loading in those cabinets and developed 6 more realistic and refined heat release rate profiles 7 for the different bins, so it's a similar analogous 8 approach to that, however it's a little more costly 9 for the development, and the application, you'll need 10 more information to apply it.
11 And then the final one is where you have 12 all of the detailed information and you're running, 13 you know, equations or correlations developed, the 14 critical heat flux or critical incident energy to your 15 fragility targets or your targets that have a specific 16 fragility, and then you're tying that fragility back 17 to the calculated fluxes or incident energies.
18 It has definitely the potential to provide 19the most realistic results. However, it is very 20 timely and complex to apply and it may be costly, at 21 least in the application frame.
22MR. STONE: Could I ask a quick question?
23I think it's just a quick question. Are we looking --
24 like today, we are, for a lot of fires you have for a 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 146 specific cabinet, you might have three to four fires 1based upon the heat release rates. Are you looking at 2 something similar for the HEAFs where you have a range 3 of fires or HEAFs that might occur for that particular 4 cabinet or source?
5MR. TAYLOR: So there's a number of 6 parameters that influence the amount of energy that 7 goes into the HEAF, and I think the working group is 8 trying to identify key parameters, and the one that is 9on everybody's mind is duration. That's the one that 10 has the biggest impact on the amount of energy 11 released.
12 So to get to your question, if you look at 13 the event tree that Nick put up earlier, one of the 14 intents of that event tree is to make it application 15 specific to the plant, and then when you're in 16 whatever the end state is, there would be a duration 17associated with that. So because that's the most 18 important and the least known from the OpE, that event 19tree helps us limit the scenario and the hazard for 20 your plant configuration.
21 So I think the short answer to your 22question is no. We're not trying to provide a number 23 of different HEAFs that you have to analyze for your 24 component. We're trying to make it, at least on the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 147 PRA application, easy, easier to limit to one HEAF.
1MR. STONE: That does make it easier, but 2 does it make it bounding because the, obviously any 3 particular source could have a single phase or a 4 three-phase fault, so are we looking at an average 5 heat release rate for a particular source again?
6MR. MELLY: So I don't think that is 7currently off the table. It was brought up at the 8 working group last meeting. However, the discussion 9 kind of focused around on what would the distribution 10 of durations look like and how could we potentially 11 incorporate that into the methodology?
12 So would we be doing typically a 98th 13percentile fire into 75th? I don't think we've gotten 14that far in the discussion. I don't think we're 15 leaning in that direction, but we might -- we're going 16 to be trying to inform the distribution of potential 17 event potentially using the rate as our main 18 parameter.
19 MR. STONE: Thank you.
20MR. TAYLOR: Okay, so as far as the 21 status, and I kind of covered this in the opening, but 22no approach right now is off the table. There are 23some approaches we think have more benefit than 24 others, but everything is still on the table.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 148 We need to understand and evaluate, you 1know, existing and new hazard models. So I'm going to 2 go over some of the existing coming up, and Chris and 3 Paul are going to talk about the new hazard models 4 that we're trying to develop that seem to be more 5 realistic and representative.
6 There's also kind of a balancing act 7 between, you know, how much detail do we need versus 8-- how much detail do we want versus how much detail 9 do we need?
10 So we can make, you know, the most 11 scientifically advanced model that is very 12 computational intensive and needs a lot of information 13 to support it, but in the end, that's just going to 14 make it very difficult on the application engineer to 15 apply it, so we have to balance, you know, what our 16 needs are with what, you know, what the science can 17 take us to.
18 And I think a lot of this is being driven 19also by the working group to help us form what's 20 important and what's not important so we can focus on 21 the important things for the test program as well as 22 for the risk assessment.
23 Just briefly what I'd like to do is cover 24 some of the measurements that we're making and how 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 149 they apply to the models, so measurements from the 1 phase, excuse me, from the fall testing if the 2 computer stops freezing.
3 But basically with NIST, we used a number 4 of different heat flux and incident energy gauges.
5One of them was a slug calorimeter, the ASTM slug. My 6computer froze. So the ASTM slug has been used in 7 Phase 1 of the program.
8 The tungsten slug has been developed by 9 NIST, and it was developed by them because we saw in 10 some of the Phase 1 testing that the actual copper 11 ASTM slug melted.
12 So because of that, we needed something 13 with a higher range, and NIST went and they developed 14 a new tungsten slug to provide us that heat flux 15 information at a much higher range, and we also have 16 plate thermometers.
17 So those three gauges provide us basically 18 the thermal information or the thermal insult 19information from the HEAF exposure. We've put a 20 number of those devices on an instrument rack that we 21 have positioned three to six feet away on the sides, 22 and the front, on top, so we can kind of characterize 23 any geometrical differences between the hazard.
24 And then also on Sandia's side, and I 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 150 don't have it on the slide, they're using some of 1 their advanced imaging equipment, thermal imaging 2 equipment, as well as high speed cameras to evaluate 3 the thermal impacts geometrically away from the test 4 equipment, as well as being able to use it to predict 5 measurements of particle velocities, particle sizes, 6 and composition.
7 On the composition side, we're also using, 8 well, in the past, we used aerogels, but we're using 9 black carbon tape to capture particles and do posttest 10 analysis to understand different information as far as 11 concentration, and particle sizes, and oxidation 12 levels.13 And the last piece of information that we 14 include in our test racks are another device that's 15provided by Sandia. This is a piece of PVC, and from 16 that, we can put it and expose it to the HEAF, and 17 then using spectroscopy methods, they can go back and 18 look at it and determine what the peak temperature was 19 at that location where that device was located.
20 On the electrical side, obviously KEMA is 21 measuring the voltage current profiles, so we have 22 that information as well as the time information that 23 will allow us to estimate what the energy was 24 delivered electrically to the device at the short 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 151 location.
1 We also have pressure measurements 2internal to the cabinet. So in the fall, we took four 3 pressure measurements, and I do have some of the clean 4data presented here. We're getting much cleaner data 5 than we did in Phase 1 because of some of the 6 improvements to the fiber optic system that's being 7 used at KEMA.
8 Other things that are important to the 9 models are physical dimension, so bus gap, how far the 10 phase is separated, as well as distances to where 11 we're actually making the measurements.
12 So before we do any testing on the 13 equipment, we spend about a week at the facility 14documenting the equipment configuration sizes. We 15 have CAD drawings of the equipment that we test.
16 So in the end, we can understand not only 17 geometrically what portion of the cabinet or the 18 equipment was damaged, but also we weigh a lot of the 19 materials, the panels, the bus bars, so on and so 20 forth, so we know what the mass loss is, so that gets 21 into the measurements.
22 Now looking at the overview of existing 23models, there's a number of models out there. There's 24 probably in excess of 20 models that are available to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 152 estimate incidental energy or heat flux, and what I've 1 tried to do here is focus on some of the more common 2 models that are used for, again, this is from the arc 3 flash personal safety standpoint.
4 So the first one comes from back in 1982 5 from the Dr. Lee model, and it basically provided a 6 simple configuration. It was theoretical in nature.
7 So you basically assumed an arc volume, 8 and then you knew your distance to your target so you 9 could extrapolate that geometry to your target, and 10 then using convention heat transfer mechanisms as well 11 as an assumption on the maximum arc power, he was able 12 to determine what the incident energy was at that 13 distance, and then using some research from Stoll and 14 Artz on the human skin and clothing fragility, he tied 15 that incident energy to second degree burns on humans.
16 So the approach in a lot of these models 17 is very similar, but this was kind of the first 18 advancement in understanding the other electrical 19 hazard as he termed it back in 1982.
20 So it was used in the 1584 2002 version.
21 However, they just updated that last year, and while 22 they do mention his work, they don't include it for 23 greater than 15 kV cases.
24 So in Lee's model, the outputs, basically 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 153 energy inputs are voltage, time, bolted fault current, 1and distance to your arc point. So if you look at the 2 measurements that we're using, you can see for the 3 incident energy, we can use the ASTM slugs and the T-4caps. For the voltage, time, and bolted fault 5 current, we can use the KEMA Daq.
6 Now, one thing that is slightly different 7 from his method and what KEMA has is KEMA is going to 8 report the arc current, which is going to be different 9 than your bolted fault current because the arc has a 10 certain impedance associated with it.
11 There are methods out there to convert 12 bolted fault to arcing fault, so I think we have that 13 captured based on those other methods, but the 14 measurement KEMA is making is arcing fault current and 15 not bolted vault, and then distance obviously through 16 physical measurement. We'll know what the distances 17 are between our machine component and we're taking the 18 measurements. So that was a theoretical model.
19 Moving on, there have been some other 20semi-empirical models put together. The Wilkins Model 21 again uses incident energy as the output, which we can 22 get through the ASTM slugs and T-caps, but also it has 23 a lot more inputs to it.
24 So you have a variety of voltages, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 154 including system voltages and arc voltages, as well as 1 current and time, all of which can be developed or 2 collected from the KEMA data acquisition system.
3 Physical measurements include distance to the arc, 4 enclosure dimensions, and the gap between the 5 conductors.
6 And then the last piece is you need to 7 know your electrode voltage, so you can get that from 8literature. Electrode voltage is basically the 9 voltage drop between, around your cathode or your 10 anode between the arc.
11 So Gammon took that model and basically 12simplified it. So again, it has a lot of the 13 information that was just simplified from the previous 14 model, and again, we can use the devices that we're 15 using at KEMA to measure testing to support that model 16 evaluation.
17 Another simple, but fairly used model is 18the model shown here. Basically it has two different 19 configurations whether you're in ambient air, open 20 air, or a box configuration. So it produces the max 21 incident energy as an output, and as input, we need 22 the currents, durations, and distance to the device 23 and target.
24 One of the most common approaches for 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 155 estimating incident energy is the IEEE approach. In 1 2002, they developed guidance which eventually got put 2 into a regulation for OSHA, and basically they used 3 200 tests to inform that model.
4 It is empirically statistically derived, 5 and what it does is basically provide a number of 6 boundaries for worker safety dependent on the type of 7 incident energy and the type of protection that 8 they're required to have to work on energized 9 equipment.
10 So the outputs, once again, it's incident 11energy. Inputs are voltage current, time, gap 12 conductor, or conductor gap, which, you know, is used 13 as a surrogate for arc voltage, distance to the 14 target, as well as some coefficients based on some of 15 the experiments that's used that you can pull from 16 literature.
17 As I mentioned earlier, they just released 18a new version. They included an additional 1,800 19 tests and they increased the number of configurations.
20So in 2002, it was just opened or closed box. Now 21 they have vertical or horizontal closed and open 22 configurations.
23It's a much more complex model. It was 24 statistically derived to match up with all of those 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 156 experiments, but if you look at what the range of that 1model covers, it pretty much covers everything that 2we've experienced inside the plant. So, you know, for 3 applicability, you know, it seems applicable for what 4 we're dealing with.
5The output is incident energy. We can get 6 that from our slugs. The input is current, voltage, 7duration, distance to the device or the target, 8 conductor gap, enclosure dimensions, as well as 9 equipment configuration, and that relates to the 10 orientation between the busses or the conductors and 11 the target has an impact on the incident energy 12 received.13 Okay, so those are kind of the common --
14 do you have a question?
15 MR. STONE: Yeah, I apologize. I wanted 16 to go back to the distribution issue on the, like on 17the types of heat release rates. The rest of our fire 18 PRAs include a distribution of the impact and we model 19 it. We can model it in a manner in that way.
20 I want to make sure that the approach that 21 we go for here is not a bounding approach that has 22 some sort of likelihood of failure if we're going to 23 use a distribution of just one failure, one frequency, 24 or the ability to use a distribution and have 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 157 different initiators for the same cabinet, for 1 example.
2 Because otherwise, I'm sure I'd want to go 3 to another, after all of these tests, to go to a 4 conservative method for what the frequency is and the 5 distribution. I'm a little concerned on that if you 6follow my question. I may not be articulating it 7 well.8MR. TAYLOR: Let me just give a few things 9on it and you probably can answer it better. I think 10 I understand the concern with the distribution, and I 11 think what Nick will tell us is that the duration is 12 kind of where we're going to address that.
13 MR. STONE: Yes.
14MR. TAYLOR: All of these other parameters 15 like voltage, and current, and conductor spacing, we 16 can make that application specific, so we kind of 17cover that there. The unknown, this uncertainty is 18 the duration of the events, but I think that's --
19MR. MELLY: Yeah, that's kind of what I 20 was going to say, that we're not trying to give a one 21size fits all. We are trying to cover the range of 22applicability for these types of events. Some of the 23 complication comes in when we even look back all the 24 way to frequency in that the frequency of having one 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 158 of these HEAFs is already this large energy release.
1 So we're kind of hardwiring in the fact 2 that this is a very energetic event, whereas those in 3 the typical heat release rate mind frame where if I 4 have a low heat release rate of 10 or 20 kilowatts, 5 that's the lower end of the distribution.
6 MR. STONE: Yes.
7MR. MELLY: Well, those events aren't even 8 included in the frequency at all, so there is some 9 correlation between how we define the frequency and 10 then how we're doing the modeling. So we are trying 11 to take in probabilistic effects in terms of duration.
12 However, we're mindful as well of what's constituting 13 that frequency at the forefront.
14 MR. STONE: I understand. I guess I was 15 a little bit concerned about that we were making -- we 16 were concerned it might become complex, and I would 17 rather spend more money and resources to get the 18 answer right, especially on a GI response or something 19 like that, than to try to go with a simplified 20 approach, at least to have the option once the methods 21 are developed.
22MR. MELLY: Yeah, and that is an active 23 area for the working group where some of the concern 24 is that if we went with kind of the two to three type 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 159 scenario approach for a single cabinet, without a 1 really good way to handle the probability of having a 2 two-second, four-second, 10-second type fault, you 3 could have vastly different target sets that are 4 associated and damaged in each of those events.
5 MR. STONE: Okay.
6 MR. MELLY: So we're trying to deal with 7 how to make that assessment right now, and we think, 8 or at least we're leaning towards duration as being 9 the primary parameter that can drive our assessment, 10 which is why our table that we put up, the fault tree, 11 sorry, the event tree kind of style there will lead us 12 to a path of selecting a duration which will then link 13 with the zone of influence depending on our situation, 14 so we're hoping that it will be addressed through our 15 current framework.
16MR. STONE: All right, thanks. As I said, 17 just to have the option of the more complex if there 18 is more data available to do a more realistic 19 assessment if that's possible would be --
20 MR. MELLY: Yeah.
21 MR. STONE: -- preferable.
22MR. MELLY: And those are things that 23 we're absolutely taking into account, and we are also, 24 a lot of the working group is very application 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 160 oriented in that we're understanding what information 1 is easy to get at the plant.
2 If we tell you, "I need to know the gap 3spacing. I need to know the manufacturer. I need to 4 know exactly what's in the cabinet," and then I go to 5 my plant personnel and they say, "Well, I don't have 6 that information." 7 MR. STONE: Yeah, I understand.
8 MR. MELLY: We're trying to, we're going 9 to try and link all of that together so we're not 10giving a fully bounding approach. It may be useful to 11 have a bounding approach in terms of resources, but we 12 hope to have the ability to sharpen the pencil and get 13 more detail oriented information.
14 MR. STONE: Thank you.
15MR. TAYLOR: Okay, the last piece, at 16 least on the thermal hazard modeling, was just a quick 17 comparison between some of the models to the data that 18 we had from last fall for the medium voltage 19 switchgear tests.
20 So this first slide here, I'm looking at 21 the ASTM slugs, which is basically a thin copper disc 22 thermal couple on the backside of it to take the 23 measurement, and comparing the 1584 2018 version to 24 our measurements.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 161 And the maximum overprediction between the 1 model and our actual measurements for all four tests 2 was almost 11 times what we observed in testing, so we 3 measured, you know, 550 kilojoules per meter squared 4 and calculated, you know, 6,100 kilojoules per meter 5squared. On the minimum side, the minimum 6 overprediction was about a factor of two.
7 So the only note, there were, in one of 8 the experiments, there was some damage to our 9 instruments, so that may affect, if we had that 10 information, it may affect these results, but without 11 that, that was kind of the comparison between the 12 experimental and at least this model.
13 You can also look at those ASTM slugs and 14 compare it to the Lee model. We already know Lee is 15 going to be conservative because of his maximum power 16 assumption, and because of that, you can see it's 17 17 times max and three times minimum overprediction with 18the model compared to our results. If we look at the 19--20MR. HAMBURGER: I have a question from 21Steve Turner. There's a question from Steve Turner on 22the webinar about the 1584 model. He said, "You 23 mentioned the IEEE 1584 model has a minimum distance.
24 Is there a maximum distance for applicability?" 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 162MR. TAYLOR: I'd have to look. I don't 1 know off the top of my head.
2 MR. HAMBURGER: Okay, thanks.
3MR. TAYLOR: So for the -- there we go, 4no, back one. So then if we look at the T-caps or 5 tungsten thermal capacity slugs that NIST developed 6 which have the higher range and we compare those to 7 the model, maximum overprediction of 26 times and a 8 minimum overprediction which was near, you know, 9 fairly close to what we measured.
10 So one thing with these slugs, because 11 they have a higher range on the lower end of the 12 exposures, they tend to underpredict the thermal 13 energy received, so that's why you can see some of 14 these maximum overpredictions being much higher than 15the ASTM slugs. If we use the same T-cap data and 16compare it to Lee's model, as expected it's an even 17 higher overprediction.
18 So, you know, the question that we get 19 asked, "But what can we use to assess the hazard?" and 20 we looked at existing models. And from what we -- I 21 put them here, but as well as what I've looked at from 22 other models, it seems like a lot of them are 23 overpredicting by quite a bit compared to what our 24 measurements are.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 163 So we're looking to better understand why 1the overprediction is. Some of the reasoning is, 2 well, the tests that they ran were either in open air 3 or they were in a box, a cubicle with one end open.
4 So if you look at the OpE, you know, 5 there's only a few cases where you actually have an 6 open compartment, and typically a lot of these events 7 happen in a closed compartment, and you need to get 8 some burn through the enclosure to actually allow the 9 effluent or the energy to really exit the enclosure.
10 So that's one area that we're looking into 11 as possibly being a difference, but if you look at all 12 of these models, they follow a very similar approach, 13 and it's an approach that we're looking to use with 14 some of the CFD modeling that Sandia is doing.
15 That is we understand what your electrical 16 energy is, any contribution from the metal reaction, 17 and then you transfer that energy out to your targets, 18 and then once it's transferred out to your targets, 19 you understand what the fragility of your targets is 20 and you can see whether those fragilities are exceeded 21 or not.22 So the last point I wanted to make is, you 23 know, there is some potential for, although they 24 overpredict, there is some potential for the existing 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 164 models to be modified to make them more applicable and 1 more in line with what we're seeing.
2MS. VOELSING: This is Kelli Voelsing with 3EPRI. I think you mentioned at the beginning that 4 most of these models were developed primarily, as it 5says on the slide, for protecting humans and 6 developing PPE.
7 So, I mean, in that situation, it might be 8 desirable to have a conservative model that gives you 9 a higher than actual heat so that you're developing 10 your PPE to protect against that.
11 So maybe it's not surprising that these 12 models are conservative because it's good for them to 13 be conservative and bounding. Have you investigated 14 that?15MR. TAYLOR: I haven't looked into that 16too much. I do know that some of the models in the 17 1584 2018 edition have so many parameters in them that 18 they had to high-fit the data.
19 So from those cases, it doesn't appear 20 that they tried to look at what the worst case data 21was and fit a model to that. They used all of the 22 data, and through a very complicated statistical 23 regression model, they fit the model to that data.
24 But I think it's a valid point that on the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 165 personal protection side, you may want to, you know, 1stay on the conservative side. I mean, that's one of 2 the logic that Lee used when he put it together was 3 that, as well as he couldn't predict what the phase 4 difference between current voltage could be to 5 estimate the power, so he assumed the worst case.
6 Regardless, I think all of these models 7 follow a similar form, and there are potentials that 8-- there is a potential for us to make some 9 modifications to that form to more accurately 10 represent the hazard that we're seeing.
11 MR. MELLY: Yeah, another important note 12 here is that all of these tests were performed at very 13short durations compared to what we are testing. The 14 other piece to that is while they may be beneficial to 15 be conservative for human protection, in the model 16 itself, we don't see any explicit safety factors that 17 are being applied.
18 So the question that we have right now is 19why are they overpredicting by so much? Based on what 20 we've looked at, we don't see any safety factors put 21 in for conservatism.
22MR. TAYLOR: The last topic I wanted to 23 cover before I turn it over to Sandia is that, you 24 know, the working group is continuing to progress 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 166 through, you know, measuring different information 1they give back to the working group. So one of those 2 is air holdoff voltage, and we looked at using the 3 EPRI mock switchgear test unit to evaluate the arc 4 over effects.
5 Unfortunately, we couldn't procure or use 6 that in the upcoming tests. So one thing we did was 7 looked at Sandia and said, "Okay, is there any way to 8 measure air breakdown strength?" And basically they 9 came back to us with one approach that has a standard 10 associated with it, and we looked to doing that moving 11 forward.12 So the whole reason why we're looking into 13 this is basically in some of the Phase 1 OECD test 14 results, it showed that when we ran an experiment, 15 some of the unenergized conductors that were in this 16test cell, after the tests, were nonfunctional. So 17 you had a lot of surface deposition on those 18 conductors and it reduced the insulation between those 19 conductors so that it couldn't function and required 20 a significant cleanup or remedy to make those 21 functional.
22 So that's the surface piece, but also the 23 question arises, "Well, what if we have another piece 24 of equipment in the room? You have all of these hot 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 167 gasses and metal particulate that's being transported 1to this other equipment. Are there any potentials for 2 the other equipment to arc over?" 3 So if you have another set of, you know, 4 6.9 kV gear in the room, can a HEAF in one lineup 5affect the other lineup of gear? So we're looking at 6 measuring in the upcoming tests what the breakdown 7 strength is.
8 There is a model that Sandia came across 9 in their literature review that estimates the air 10 holdoff or breakdown strength based on temperature as 11 well as the concentration of metal vapor in the medium 12 or the air.
13 So the plot that's shown here is basically 14 showing ambient conditions where, you know, air has 15 basically a 30,000 volt per centimeter holdoff 16 strength.
17 As you add, you know, a certain 18 concentration of metal vapor to air, it decreases, 19whether it's copper or aluminum. If you increase 20 temperature, it also decreases the holdoff strength, 21 so you can see gas density or temperature, as well as 22 metal vapor concentration has an impact on what your 23 holdoff strength is.
24 And also something worth noting is 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 168 aluminum ionizes more easily than copper, so that has 1 some of the impact of why the aluminum is showing a 2 lower holdoff strength than the copper.
3So with this model, what we looked at 4 doing is running these holdoff strength measurements 5 and using the data that we received from the tests 6 that we performed this fall to look at this model and 7 how well it characterizes the concern.
8 So the approach is based off ASTM D2477, 9 test method for dielectric breakdown voltage and 10 strength of insulated gasses at commercial power 11 frequencies. However, if you look at that standard, 12 there are some things we needed to modify.
13 Because the HEAFs are such short duration 14 events, we needed to change how the voltage profiles 15 applied to the device, so we made adjustments that 16 allows us to rapidly increase the voltage a number of 17 times throughout the duration of the HEAF event such 18 that we can make multiple measurements during one 19 test.20 We're also looking at using ultraviolet 21 illumination to ensure that there's consistent results 22 to standard step voltage approaches. So in the end, 23 it allows us to determine what the actual holdoff 24 voltage strength is and any confirmation of the model.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 169 It looks like this slide is missing a 1photo on the top left. It was just a photo of the 2actual probe. So basically if you look at the 3 illustration in the middle, the blue, basically you 4have two spheres that are separated, metal spheres 5 that are separated a certain distance apart.
6You apply a voltage between that. As your 7 air medium goes between those probes, if it has, you 8 know, low enough, or high enough conductance between 9 the probes, it causes a breakdown of the air and we 10 can measure that with the instrument's current voltage 11 instrument that's being used to capture it.
12So we plan on using two units. The 13 evolution of the deployment of the units are going to 14 be iterative. So initially, we're going to put them 15 in open air, run a test, make sure that after the 16test, make sure that they're in the cloud or the 17 effluent from the HEAF.
18 If they weren't, in the subsequent tests, 19 we're going to make adjustments to make sure that 20they're in that cloud and run the test again. And 21 then with the data from those two tests, we're going 22 to be able to look at National Electric Code 23 requirements for holdoff strength and see if we exceed 24 those. 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 170 If we do exceed those, then we're going to 1put it in an enclosure and run tests again. If we 2 don't exceed those, well, then it shows that it's 3 probably not an issue.
4 But regardless, I think we're going to 5 continue to run these measurements throughout this 6 upcoming test campaign to make sure we can better 7 understand what any holdoff strength is in open air as 8 well as in an enclosed compartment.
9Oh, there is the photo. So basically it's 10 just a photo of arcing between two of the spheres.
11 As far as where we're going to put it in 12 the test cell, probably anywhere between eight and 12 13 feet away from the test object, four to six feet above 14the floor, typical locations where you're going to 15 have, you know, energized conductors within the room.
16 We're going to measure the temperature of 17 particle concentration and current voltage, and all of 18 it in the system and configurations shown on the 19 right.20So that's it for my presentation. Are 21there any questions? Is there anything on the 22 webinar?23MR. FLOYD: Yeah, Jason Floyd from Jensen 24Hughes, just sort of a question. You have the various 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 171 sort of simple empirical models and we've shown, okay, 1a factor of two to, you know, whatever factor of 2 conservatism.
3 Is there plans or have you thought about 4-- I mean, we have all of the information on plant 5 configuration that we've collected, and the voltages 6 and potential durations, of at least assessing what 7 the model says they exist now.
8 You know, where do we think the ZOI sits 9 gives us some confidence that, yeah, we've got a 10 problem we need to investigate, but if these 11conservative models say that, you know, we're not 12 there, then, you know, that might cause us to rethink, 13 and also the check for, you know, instrumentation 14 placement in these tests?
15MR. TAYLOR: So on the first piece, the 16 modeling, and have we done any work to kind of assess 17 where we're at with the current modeling, we haven't 18 done anything formally in the working group.
19 But what I have done kind of on the back 20 of the envelope is to look at some of the literature 21 that's available comparing copper versus aluminum, and 22 there is some literature that's been done that 23 basically it takes the input and output and relates it 24 by one parameter, I think they call it an effective 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 172 heat transfer coefficient, and basically it shows that 1 you have, you know, you can have about three times as 2 much energy from an aluminum versus a copper.
3 So with that information, I used 1584 as 4 well as the existing PRA guidance for the three-foot, 5 five-foot, and compared, you know, what could it be 6 with an aluminum assuming 6850 based on copper? And 7 from that, it took it to anywhere from six to 12 feet 8 from the three-foot.
9MR. FLOYD: With the conversatisms that 10 we've seen, so.
11MR. TAYLOR: Yeah, so assuming 6850 is 12 conservative, which, you know, it's meant to be a 13 bounding approach, we're not sure it captures 14 aluminum, but it's a bounding approach, and 1580, you 15 know, the heat transfer.
16 Now, it wasn't using all of the 17 information to extract that because you needed 18 fragility, right? So I used like a common fragility 19as kind of a baseline. So I tied it to that baseline 20 fragility and then converted it for the aluminum.
21So, yeah, I think the short answer is 22 there is some conservatism in that approach, but if 23 you're looking for kind of a what could it be? It's 24 somewhere in that window, and until we -- That's what 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 173 the working group is trying to do is, "Is it closer to 1 the three foot or is it closer to the 12 foot?" 2MR. MELLY: Yeah, but in terms of have we 3 done the Lee approaches that have the 39 times 4 conservatism built into the output, and then linked 5that with a theoretical fragility for what cables 6 would say, and done what our postulated zone of 7influence would be? No, that has not been completed.
8 I don't know if that would be a useful 9endeavor. It's definitely something we should try and 10 investigate, but with a conservatism anywhere from 17 11 to 39 times what we're seeing in testing, we may be 12 vastly overpredicting the zone of influence, and 13 again, we do have to link it with the fragility data 14 which we're incurring the stages to develop.
15MR. FLOYD: Yeah, well, I'm just 16 suggesting that if you have some estimate on the bias 17for your model, you can do a prediction and correct 18 it, and at least, you know, get some ballpark as to 19 where we think we are.
20 You know, make sure that we're thinking of 21 our test instrumentation and what we're thinking 22 about, and at least it's better to go in with some 23 ballpark and help guide your thinking than to sort of 24 go in blind.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 174 I mean, we've got data to at least get 1 some rough assessment, you know, for whatever it's 2 worth, you know, to sanity check what we're thinking 3 or testing.
4MR. TAYLOR: Yeah, it's a good point, but 5 as far as, you know, at least our logic right now, 6 where we're putting our instruments for the instrument 7 racks, you know, we're tying that back to the 6850 8model, so three foot, and then six foot, you know, 9 between that.
10 For some of these other measurements like 11 the conductivity measurements, we're looking more for 12 the far fields, not the -- outside of the thermal 13effects, so that's why we're putting those farther 14 away, possibly back against the far wall in a test 15 enclosure, which would be dependent on where we can 16 put the actual test device, but, you know, you're 17looking at 10 to 15-foot away from the object, test 18 object.19MR. HAMBURGER: We don't have any 20 questions on the webinar at the moment. Anyone else 21 in the room, a question or a comment?
22Give us two minutes to pull up this 23 presentation. Our computers are --
24 All right, let's take a 15-minute break 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 175while we get this sorted out. We'll come back at 1 2:45. 2 (Whereupon, the abo ve-entitled matter went 3 off the record at 2:28 p.m. and resumed at 2:44 p.m.)
4MR. HAMBURGER: Okay. It's 2:45. We have 5 sorted out our computer issues and, Gabe, you want to 6--7 MR. TAYLOR: Sure.
8 MR. HAMBURGER: -- introduce the Sandia 9 folks?10 MR. TAYLOR: So, apologize for the little 11glitch on the computer. Welcome back, everybody. So, 12 the next slide set will go through the HEAF modeling 13 effort that's being conducted by Sandia National 14 Laboratories, basically providing the modeling 15 approach and analysis.
16 So, why are we doing this?, is basically 17 a question arose you have this aluminum that showed in 18 Phase 1 to be an issue, what can we do better to model 19it? So, with that, we started looking around, 20 initially, we were looking at going to one of the 21 universities, but that resource is no longer 22 available.
23 So, we identified that Sandia had a lot of 24 capability and existing models and expertise that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 176 could be used to help address this issue and the 1 question, so we turned to them for their expertise to 2 help us develop that asset.
3 So, in front of me, or here with me today, 4 we have Dr. Chris LaFleur, from Sandia, as well as Dr.
5Paul Clem. And they are going to provide that 6 information. Chris?
7MS. LAFLEUR: Thanks. Yes, I'm Chris 8LaFleur. I do fire risk studies at Sandia National 9 Laboratory, and Paul is in the electrical science and 10experiments group. There's also two other members of 11 our team, it's a complex problem, as we've said, so 12 we've got some other resources on the line that you 13 may hear from today.
14One is Matt Hopkins. He is our expert on 15ARIA. He was involved in the development of it, so he 16 can speak to its applicability on environments that we 17 experience in a HEAF event.
18 I also have Caroline Winters on the line 19 and she is working on the small-scale experiments and 20 measure the spectral emissions from those arcs. So, 21 next slide.
22 So, our general overview of what we're 23 covering today, we have a few slides on the background 24 of why we're doing the physics modeling, Paul will 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 177 cover those. And then, we have our overall plan for 1 the arc modeling.
2 And then, a lot more details on the 3 approach of how that arc will be modeled and how that 4 will hand off into characterizing the thermal 5 environment and other hazardous environment that is 6 emitted from the HEAF.
7 We'll talk more about the next steps that 8we're going to do for the modeling. Paul has some 9 results of our current tuning of the model and where 10we're at. We have details on the Sandia National Lab 11 models, the ARIA and FUEGO models that can be coupled 12 together. And Matt will give that information.
13 And then, I have a few slides on where 14 we're at evaluating the target fragility and the 15failure criteria. And that's where my voice is 16leaving me. So, I'm going to let Paul talk about the 17 next few slides.
18MR. CLEM: Okay. Great, thanks. So, I 19 think it's been pretty clear from what Gabe mentioned 20 that there's a big disconnect, in many cases, between 21 some of the empirical models or calibrated models for 22 arc energies and what's really measured in HEAF 23 events.24 And on top of that, part of the reason we 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 178 were brought in, I believe, is to look at the effects 1 of aluminum and how could we begin to quantify why 2 aluminum and copper behave so differently in 3 switchgear or in busbars and other kinds of operating 4 equipment.
5So, there's really a desire to have a 6 physically-based model to understand what is the 7effect of aluminum during a HEAF? Is it oxidation, is 8 that the primary driver? Or are there other factors 9 that really affect the total radiant energy that comes 10 out of that?
11 And furthermore, can we make models that 12 are much less conservative going forward, that are 13 physically-based, they're not calibrated, they're not 14 based on these square fits, they're really based on 15 the physics of the model and really get much closer to 16 really what's going on?
17 So, that's really the goal of this, is to 18 have a physically-based, demonstrably correct model of 19 the energy that comes out of a given piece of 20operating equipment. We'd like to do that simply 21 knowing the current going into the switchgear or the 22 equipment, the gap between electrodes, and the metal 23 composition.
24 So, have no other calibrated factors, no 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 179 other fits to the data, just simply look at the 1 physics basis for air conductivity, how does the 2 plasma develop, and what is the energy radiated out 3 from that plasma?
4So, if you go to the next slide? And this 5 would let us look at a much wider variety of 6 components and situations. So, this isn't a problem 7 just for nuclear plants, we actually were brought in 8 earlier for another EPRI program, looking at 9 photovoltaic DC arc faults, where photovoltaic 10 facilities, basically a constant current source, and 11if an arc fault develops, you can have a very 12 extensive DC arc fault and it was found that many of 13 the predictions from arc damage from DC arc faults 14 were also not well-grounded.
15 So, we began developing a model for 16 looking at DC arc faults, based on the physics, and it 17 turns out that this should overlap very closely with 18AC arc faults, as far as the basic physics. So, 19 that's where this is going.
20 So, we're working with Tom Short on DC arc 21faults, open box experiments. In fact, we just 22 tested, up at Detroit Edison, last week, on switchgear 23combiner boxes, recombiners, and invertors. So, next 24 slide.25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 180 So, for the DC arc problem, a similar 1 problem, DC arc faults, as to some of the AC models, 2 the concern there is about what's the right PPE for a 3 given arc fault event?
4 And you can see, if you look at the 5 different models there, the green, navy blue, yellow, 6 and royal blue are the predicted incident energies 7 that are in the literature.
8 And it ranges from PPE 1, all the way to 9 PPE 4, depending on which model you believe. So, it 10 can be extremely conservative, factor of ten 11 conservative, in many cases, and the goal is to have 12 a much more accurate prediction.
13So, if you look at the actual measured 14 data in red, and you're able to actually reproduce 15 that very closely with a model by Stokes and 16 Oppenlander, in the yellow curve.
17 And this is based on some previous work on 18 both DC and AC arc flashes and arc faults by Lowke.
19 So, we're basing our work on this Stokes and 20 Oppenlander model, which is really a physics-based 21 model, it's not a calibrated fit.
22 But the goal for the EPRI EERE PV work is 23 to make an arc physical model, where if you know the 24 DC current, you know the gap between any two terminals 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 181in that operating equipment, you can predict the 1 energy transfer out of that HEAF.
2 That energy transfer is not just an 3 energy, it's actually composed of three different 4kinds of energy. There's radiant energy transport, so 5UV, visible, and IR radiation comes out. There's 6 convective energy transport into the air around the 7arc itself. And there's thermal energy transport, 8 which is direct conductivity of heat into the 9 electrodes.
10 And those are not accounted for or 11separated in the current models, there's just an 12energy that's delivered to some point in space. We'd 13 really like to separate those out, it's critical to 14understand what form that energy is in. Is it UV? Is 15 it visible? Is it air?
16 There's different speeds, obviously, of 17light and of conduction through air. So, it really is 18 important, we believe, to include those in any kind of 19 damage assessment moving forward, and having a 20 physics-based model lets you get that data and look at 21 how that's going to be absorbed on equipment, on 22 wires, on other kinds of components, and then, look at 23 fragility criteria based on that real energy and how 24 it comes out.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 182So, if you go to the next slide? So, our 1 goal is really to start that basis of the DC arc fault 2model, and then, extend it to AC arc fault models.
3 So, there have been a number of international studies 4 looking at arc faults and some of the -- in AC 5 equipment.
6 One of these was by the CIGRE Group in 72014. And, again, the goal here is to develop an 8energy input term that can be used, based on the 9 geometry and the current going into an arc fault, but 10 that can then be taken into any other model following 11that. It could be used in FDS, it could be used in 12 GOTHIC, it could be used in OpenFOAM, FireFOAM, or 13 other kinds of CFD models.
14 But a note they made in their analysis is 15 that the current models look at energy input, but it 16 says the most complete approaches, where the arc could 17 be modeled using physical equations, describe the arc 18 roots, where the arc attaches to the electrodes, the 19 arc plasma column itself, the effect of magnetic 20 fields on the motion of the arc, and the transfer of 21 the energy from the arc plasma to surrounding gases 22 have never been applied to internal arcs to our 23 knowledge.
24 And that's the gap we're trying to fill 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 183here. So, we're trying to make an accurate model that 1 really looks at the real physics of what's going on 2 with the arc.
3 So, again, we want to take the AC current 4 and electrode gap and electrode materials and be able 5 to predict the radiation, convection, and thermal 6energy transport by conduction with these models. So, 7 next slide, please.
8 MS. LAFLEUR: Let me comment?
9 MR. CLEM: Sure.
10MS. LAFLEUR: Okay. So, this is our broad 11 plan, overview for how we're going to go about the 12modeling. And the first -- well, the vision is to get 13 a non-conservative, I think we all agree on that, non-14 conservative estimate of credible energy release 15 scenarios and the respective zones of influence for a 16 range of appropriate equipment in nuclear power 17 plants.18 And the first thing we need to do is 19 develop a model that can characterize the arc, the 20 physics of the arc and what's emitted from the arc.
21 And we would like to do that in ARIA, which is a 22 Sandia model we'll talk a lot more about.
23 We will need to couple this to a model 24 that's capable of characterizing the affluent, the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 184 thermal plume from a HEAF. And we have a fire model 1 called FUEGO.
2 But as Paul was saying, we could use a 3 number of different models that would take the output 4 from ARIA, that source term, and predict the extent of 5 thermal heat flux and energy emissions to targets, 6 right?7 Either predicting the breach of when an 8enclosure, the source enclosure would breach. We 9 could also, in that other model, predict when a target 10 enclosure could breach, if it's subjected to a high 11 enough environment for long enough, right?
12And we could use that to evaluate the 13fragility. Evaluating the fragility is completely 14 separate from the source term, we're thinking of that 15completely separately. Our source term models will 16 characterize the extent of a plume or an envelope of 17 hazardous conditions.
18 And then, we'll use the knowledge that we 19 get and work out in the working group for when cables 20 or other equipment fail, when exposed to that 21 hazardous condition and we'll be able to cross those 22 together.23 Just like the existing conservative models 24 looked at the fragility of human skin, they know the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 185 heat flux of when you get a second-degree burn based 1 on how long you're exposed to that heat flux, very 2 similar model for looking at when cable or an 3 enclosure might breach.
4 As Paul said, we want the input parameters 5 to be the current, the type of material that's 6involved in the HEAF, and the gap. We want to be able 7 to predict distances to critical temperatures or 8fluxes or failure criteria. And that's going to allow 9 us to develop the zones of influence.
10 We'll run the model at Sandia and within 11 the work group. We don't intend the model to be run 12 by licensees or other people, it's not going to be a 13 commercial software that gets developed and 14 distributed for people to do.
15 What we'll generate is the look-up tables 16 for what the energy, incident energy, that's emitted 17 based on the duration of the arc and the type of 18 equipment.
19 Types of things that we need to measure, 20 in order to validate that model, are incident energy 21 and the three different types of energy that's being 22 emitted, as Paul said, the thermal energy, the radiant 23 energy -- what was the third one?
24 MR. CLEM: Conductive.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 186 MS. LAFLEUR: Conductive energy, there we 1go, thermal field. And we'll do -- we need to measure 2fragility parameters. Like Nick was saying this 3 morning, we can't do that in the KEMA facility, but we 4 can do that separately at Sandia, based on what 5testing is identified as what we need to. Next slide.
6 So, first thing -- maybe you should talk --
7 MR. CLEM: Okay, sure.
8 MS. LAFLEUR: -- I think I'm killing people 9 with this, sorry.
10MR. CLEM: Okay. So, I think we're as 11 eager as you are, probably, to have these models be 12ready. But really, to get these models correct is an 13 iterative process, to build up the model and make sure 14 it's demonstrably correct, that as we make this, start 15 with a simple arc and move to a more complicated arc, 16 that we're capturing the correct physics.
17 So, the first parts we've put into the arc 18 model so far is the ability to look at a geometry, 19 look at the input current, and then predict such 20 things as the arc's temperature, the arc radius, the 21 radiant and convective heat transfer from the arc.
22 And from that, we can actually look at the 23 mass loss rate of the conductors, of the electrodes in 24 that arc. So, we currently prepared that basic part 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 187 of the model.
1 We've begun taking validation data for 2 that, some of it's been done at low currents, 100 to 3 300 amps. We're conducting kiloamp, and I think, 15 4 kiloamp tests this fall, the next couple months, on 5 open box tests, to help validate those initial models.
6 Ultimately, we have to include a much 7broader suite of physics in this. We need to include 8 magnetic forces, buoyancy of the gas, as it gets very 9 hot, which changes the shape of the arc, and then, the 10orientations of conductors. So, we can look at 11 vertical arcs, horizontal arcs, and then, parallel 12arcs. And each of those are going to have a different 13 behavior, we need to look at each of those 14 independently.
15 But that's the goal, again, is to have a 16 non-conservative model, that's physically accurate, 17but can be applied to multiple situations. And I 18 think the key output of this is you can look in your 19 simulation at various spacings, various metal 20 electrodes, and look at all kinds of different 21 scenarios, which we believe will be much more 22 effective than conducting experiments in the field for 23 every kind of orientation and situation that could be 24 present.25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 188 And so, again, the goal is to have an 1 energy output for each of those that is accessible to 2the community. So, if you go to the next slide, 3 please?4 So, again, the goal of this is to be able 5 to support an energy source term that could then be 6 taken up by any CFD model and then, applied to help 7 identify failure criteria and zones of influence, so 8 you can look at the radiant heat absorption, you could 9 look at conductive heat transfer, and how that leads 10 to failure criteria for given parts, whether it's the 11 outer wall, switchgear, or whether it's a cable or 12 other kind of criteria.
13 So, this is supposed to inform the working 14 group and help provide this predictive capability and 15 provide energy inputs for looking at failure criteria.
16 So, again, we're -- the key thing we're 17doing here is really replacing the open circuit 18 voltage that's used in a lot of the models there are 19 to date, the VoC with arc resistance, which is sort of 20 treating the arc as a circuit element, where the arc 21 has a known resistivity, it has a known radius, it has 22 a known length, and it's a function of time.
23 And from that, we can look at I squared R 24delta T. And I squared R delta T is the energy 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 189 output, or the integral of I squared R delta T would 1 be the ultimate energy being released by a HEAF event.
2 So, we want to look at how the joule heating energy 3 input turns into an exothermic event.
4 Again, we can measure that in these 5 calibration tests by looking first on the supply side, 6 at the arc voltage that's measured as a function of 7 time during testing, monitoring the current input into 8 the system, and that gives us the arc resistance as a 9 function of time.
10 We can measure the radiant power with 11black calorimeters. These are 99-plus percent 12 absorptive calorimeters in the UV, visible, and IR.
13 Or we can use calibrated thermal piles to separate out 14 the different fractions that are in UV, visible, and 15 IR.16 We can measure electrode temperatures with 17calibrated IR cameras. So, Sandia's thermography 18 group is involved with cameras that are calibrated to 19 3000 Kelvin to look directly at the different 20 components and calibrate their temperatures.
21 We can measure the arc temperature itself, 22using spectroscopy. So, Caroline Winters will talk 23 a bit about this, but if you capture the emission 24 spectrum of the arc, you can determine the temperature 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 190 at the edge of the arc and look at how that compares 1 with our model.
2 You can also look at the temperature 3inside the arc, through spectral emission lines of 4 aluminum and copper and other components and 5 demonstrate the arc model is getting each of these 6parts correct. So, really, it's a plasma physics 7 problem being coupled to a CFD analysis, in the end.
8 And finally, there are arc dynamics 9 associated with multi-phase arcs, especially with 10 zero-crossings and other kinds of features. We have 11 high speed cameras, up to a million frames per second, 12 that can capture the real-time behavior of this and 13 correlate that with captured voltage and current 14 waveforms.
15 So, the goal is to really understand the 16 physical behavior of the arc, the electrical behavior 17 of the arc, and then, how that turns into an energy 18 output term. Go to the next slide, please.
19 So, what we're trying to do in this work 20 is, again, have a physically-based model with a small 21number of inputs into that model. So, the inputs 22we're currently looking at are the gap between 23 conductive components. What is the electrode itself 24 composed of, is it copper, aluminum, is it an alloy?
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 191 What is the input current, the short circuit input 1 current? And then, from these, we can then generate 2 the temperature that's developed.
3 Now, air normally, of course, is an 4 insulator at room temperature, but as you heat up air, 5 it begins to dissociate and ionize and the air can be 6 separated into ionized gas species and electrons and 7 conductivity begins to turn on in air, as a function 8 of temperature.
9 So, especially above 3000 or 5000 Kelvin, 10 air by itself has a significant conductivity, due to 11 the presence of electrons that are present, and you 12 can calculate the conductivity of air as it heats up.
13 So, if you know the arc temperature, you can calculate 14 the resistance of that arc itself.
15 So, air by itself is one species, however, 16 if your plasma is in contact with metal electrodes and 17 you're having electrode erosion, those metal 18 electrodes, copper or aluminum, are first melting and 19 then, likely vaporizing, if they're above 1000 degrees 20C, to where, now, you have not just nitrogen and 21 oxygen in the air, but also aluminum and copper in the 22 air.23 And these aluminum and copper also have 24 known conductivities, as a function of temperature.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 192 You can include these in these in these m odels and 1 have very accurate predictions of the conductivity of 2 air by itself or air with some volume fraction of 3 aluminum or copper, iron from the steel enclosures, 4 all these kinds of things.
5 So, if you know those conductivities, and 6 these have been calculated for standard metals, 7 aluminum, copper, gold, silver, iron, as well as air, 8 you can predict the conductivity of air and then, air 9 including metallic vapors.
10 If you have these, as well as the density 11 of air, thermal conductivity, and specific heat, you 12 can then look at the CFD heat transfer and treat this 13 arc as a living being that has both thermal 14 properties, as well as a circuit element that has a 15 known resistance.
16 So, there's been some nice work by a group 17 in France, Yves Cressault, looking at these kinds of 18 things, looking at two-meter long arcs, at one to 40 19 kiloamps, and what happens when the electrodes are 20 made of iron, copper, or aluminum, and what the 21 effects are that are measured in terms of air 22 conductivity, and then, the effects in terms of the 23 energy output from those arcs. So, if you go to the 24 next slide, please?
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 193 So, one example is the conductivity of air 1 is much higher when it has metal vapor included in it.
2 In addition, what's called the net emission 3coefficient, that is the amount of energy that's 4 radiated outwards in the ultraviolet and visible and 5infrared also increases when you have things like 6 aluminum and iron present in the vapor, as opposed to 7 copper.8 So, what's shown here are, 100 percent is 9 your total VI or total joule heating going into the 10system. What is the fraction of energy that comes out 11 of that arc fault as radiant energy, as optical 12 energy?13 What's found is, if you look at steel or 14 aluminum, again, because these have a much higher net 15 emission coefficient of radiant energy, you're seeing 16 something like 60 percent to 30 percent more energy 17 coming out from an arc, simply due to the electrode 18 material that's present.
19 And so, some of the energy being measured 20in arc faults, in aluminum, may be due to oxidation 21and that needs to be considered. But simply the 22 presence of the electrode, of the copper or steel by 23 itself, is going to increase the output energy that's 24radiated. And that radiant energy is really what you 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 194 measure on a calorimeter at some distance away.
1 The convective heat transfer in an open 2 chamber propagates very slowly, on the orders of maybe 3 ten centimeters, six to ten centimeters is what we see 4so far, and quite slowly. If you look at the radiant 5 energy, that's instantaneous, the speed of light, 6 being transmitted out to far field objects.
7 So, simply the choice of electrode really 8 matters and this can be captured in these physics-9 based models and is not captured, as far as we can 10 tell right now, in calibrated models based on currents 11 and voltages in different systems.
12 So, if we take these models and then, 13 begin to look at modeling different systems, looking 14 at an arc between electrodes where the electrodes are 15 not interacting, to where the electrodes are composed 16 of aluminum, we can predict, as a function of input 17 current, from 100 amps or 200 amps up to 10 kiloamps 18 or above, what the output power should be.
19 Again, the output power times time is 20 going to give you the total energy from that arc fault 21event. So, if you had non-interacting electrodes that 22 were not creating vapor versus electrodes that include 23 aluminum vapor, in this case, you see a significant 24 increase in energy output.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 195 And the current model we're using, based 1 on this Lowke model or Stokes and Oppenlander model, 2 show about a 50 percent increase in expected energy 3 output, in terms of power, due to the presence of 4 aluminum.5So, again, this is -- the radiation is 6 much increased with the presence of metallic vapors, 7 such as aluminum or iron, as opposed to the presence 8 of copper in an arc fault.
9 So, we've begun making these predictions.
10 We've begun taking validation data, or experimental 11data to validate these. But it does agree with what's 12 been measured historically for aluminum electrodes.
13 So, if you go to the next slide, we're 14 taking this model by a researcher named Lowke from 15 Australia, that's from back in the late 1970s, that's 16 a simple theory of free-burning arcs.
17 And so, this is a simple assumption about 18 the way arcs behave, that allows you to treat them, 19 again, as a circuit element, as well as a thermal 20 element that's radiating energy.
21 And so, again, for a current input, and 22 simply knowing the air conductivity, specific heat, 23 density, and thermal conductivity as a function of 24 temperature, you can predict the temperature of the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 196 arc, you can predict the radius of the arc, you can 1 predict that arc resistance as a function of current, 2 and then, you can look at the energy balance that 3 comes out of that.
4 So, again, we have current feeding into an 5 arc of a given geometry and then, the output from that 6 is a combination of radiant energy, convective energy, 7 and conductive energy.
8 So, what we end up with are curves, as are 9 shown here, where, again, we can now look at different 10 atmospheres, we can look at air, air with aluminum, 11 air with copper, and really compare these quite 12 quickly, this runs on a single laptop, single 13 computer, and get rapid results for different 14 geometries, and then, begin to evaluate these in the 15 field.16 If you go to the next slide, looking at 17 this in a little more detail, the black curve on top 18 shows what's expected for the total electrical energy 19 input into the system, so the joule heating, as a 20 function of input current.
21So, we see the input power from roughly 22 three kilowatts per centimeter length of an arc, up to 23 10 to the fifth, 10,000 watts per centimeter of arc 24length. That energy input is being dispensed of in 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 197 some way by radiative transport, conductive transport, 1 and convective transport.
2 And now, it turns out, as the current 3 increases, the balance of energy coming out of that 4arc changes. At low arc currents, most of that arc 5energy is thermal. It's conducted into the air or 6 it's conducted into the electrodes.
7 As you begin to go to 1000 amps and above, 8 there's a crossover and the radiation output 9 dominates, from a kiloamp up to tens of kiloamps, 10 which is the area we likely care about for these HEAF 11 events.12 So, if you look at the ratio of those blue 13 curves, which is the radiated energy, to the orange 14 curves, which are the thermal transport energies, you 15 can look at what fraction of the energy is radiated.
16 So, again, what's sense is for pure air, 17 in the blue curve, that can be as low as ten percent, 18 and it goes up to around 80 percent, as you're 19 approaching ten kiloamps.
20 When you have the presence of aluminum, 21 you have a much higher radiated energy output in all 22cases. So, again, you're going to measure that or 23 you're going to feel that with a calorimeter at some 24 distance for your zone of influence.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 198 So, these simple isothermal arc models 1 appear to be effective and lets us do quick 2estimations. We're taking this basic model and 3 putting it into this full ARIA model, to look at more 4 complex situations, where we can go from the simple 5 model and then, include magnetic forces, include 6 buoyancy, include other effects that are really 7 important for actual arc modeling.
8 So, going to the next slide, we've taken 9 these initial models and begun to perform experiments, 10 both small-scale and large-scale experiments, to 11evaluate these. We have a couple different test beds 12 at Sandia.
13 One of these is a short duration arc, 14 where it's a capacitive discharge system, it has 15roughly 50 kilojoules of energy available. So, it can 16 perform short duration arcs from one to 100 17 milliseconds, but at high currents, a kiloamp to 160 18kiloamps. So, we can look at multiple line cycles at 19 many tens of kiloamps to hundreds of kiloamps, for a 20 short duration.
21 We have a different setup that enables 22long duration arcs, one to 120 second arcs, but at 23lower currents, only 100 amps to one kiloamp. We 24can't, at Sandia, go above a kiloamp. For that, we're 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 199 relying on large-scale testing at KEMA, in 1 collaboration with NRC and EPRI and NIST.
2 So, we have these two different 3 capabilities at Sandia, we're able to use these to at 4 least begin to benchmark these codes and look and see, 5 how effective are they?
6 So, if you go to the next slide, I have 7 some images and, ultimately, videos of different arcs, 8 if they'll come up. Unfortunately, the computer may 9 be slow.10 For the first test we're doing, we're 11looking at a very simple geometry. These are vertical 12arcs. So, we have vertical arcs, again, of different 13 metals, aluminum or copper, or we can look at other 14 materials if they're of interest.
15 We're applying, in this case, from left to 16right, 100 amps, 200 amps, sorry, 300 on the left, 17200, 100 amp. And we'll make sustainable arcs that 18 last for 30 seconds or even up to two minutes with 19 these.20 If you go to the next slide, let's see if 21this plays. So, you should be able to play a movie at 22 the bottom there. Let's see.
23 MS. LAFLEUR: It says it's playing.
24MR. CLEM: It says it's playing? Okay, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 200 it's thinking.
1 MS. LAFLEUR: There it is.
2 MR. CLEM: So, here, we show the onset of 3the arc. So, we're triggering this arc with voltage.
4We're then looking at a given arc length. We're 5 measuring the voltage and the current of these arcs 6 during these experiments, for, these are five-second 7 arcs, we've gone up to 30 seconds with these.
8 We're measuring many different factors 9about these arcs experimentally. We're measuring the 10arc temperature, using spectroscopy. We're measuring, 11 with black calorimeters, the radiant energy output.
12 We're measuring, with other calorimeters, inside a 13 closed chamber, the temperature rise in the chamber.
14 And we also can use, we're using infrared cameras, 15 calibrated infrared cameras, to calculate the 16 temperature of the electrode themselves, to look at 17 the conductive energy going into those busbars.
18 So, right now, we're looking at vertical 19 arcs, and we'll be looking soon at horizontal arcs, 20 and then, parallel arcs as well, at small-scale in 21 these experiments.
22So, if you go to the next slide? What we 23 want to do with this is then begin to see how well we 24 agree or how poorly we agree with the outputs from our 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 201 modeling.1So, again, the curves on the left side 2 here, the black curve is the input electrical energy, 3 the dashed blue curve is what we predict for aluminum 4 electrodes, and the dark blue data points are what 5 we've measured so far, at 100 amps, 200 amps, and 300 6 amps.7 And so, so far, the radiated energy 8 measured from these arcs is within 30 percent of the 9predicted energy output from these arcs. So, we're 10 continuing this work -- if you hit the button one more 11 time?12 Right now, we've been looking at low 13 current, but we'll be doing tests at higher current at 14 Sandia, up to a kiloamp, this summer at Sandia. And 15 then, at KEMA, an overlapping point at a kiloamp, and 16then, another measurement I believe at 15 kiloamps 17 later this fall, to see how well we agree, as far as 18 these measurements.
19 So, a few of the takeaways so far is that, 20 initially, at least, it's within 10 to 30 percent, as 21 far as our predictions of radiant energy output, which 22 is really what would be propagated to other components 23in the zone of influence, we believe. That's one 24 takeaway.25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 202 Another is, we really believe we can take 1 out this open-circuit voltage that's used in a lot of 2 models and really substitute it by looking at this I 3 squared R of the arc times the time duration, delta T, 4of the arc, to predict the energy output into a 5 system.6 So, if we look at the wattage that's 7 measured on the right graph as a function of input 8 current, we see these scaled quadratically, with the 9 input current, so it goes as I squared, as we expect.
10 And again, we're able to measure a number 11 of different validation parameters, the arc voltage, 12 the arc resistance, the arc temperature, and again, 13 some of the arc dynamics of this, to start to validate 14 this model and show that it's accurate or show we have 15 at least confidence that it's predicting the right 16 things.17 So, we have initial DC experiments, we'll 18 be moving in the future to AC experiments, again, on 19 an increasing current.
20 If you go to the next slide, we've begun 21 looking also at the effects of arcs on busbars. One 22 of the questions is, how arcs interact with busbars, 23 how material is evolved and liberated from busbars 24 during testing.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 203 So, we performed a number of tests last 1 year, at 480 volts, 4160, 6.9kV and 10kV. These are 2 very short arcs, around 100 milliseconds long, but we 3 wanted to look at things like mass loss of electrodes 4 for copper versus aluminum, and also volume loss of 5 copper versus aluminum, with these different arc 6 conditions and see if we could predict this with our 7 models, if it's consistent.
8 What we predicted, as shown in the upper-9 right, is that we'd expect a parabolic I squared 10 dependence of the mass loss of copper and aluminum 11electrodes. And in fact, we'd actually predict the 12 same mass loss for copper and aluminum for these 13 electrodes from the simple model.
14 When we actually measure this, the data 15 points in the bottom-right, we do see this quadratic 16 dependence, both for aluminum and copper electrodes, 17for these. So, we see an I squared R dependence of 18mass loss from electrodes. And that indicates how 19 much vapor or how much molten material is being 20 generated by these arcs.
21If you go to the next slide, we were a 22 little confused by why the masses were exactly the 23same for copper and aluminum. I think we see, in the 24field, that there's much more aluminum loss. It turns 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 204 out that you need to normalize the mass loss by the 1 density of aluminum versus copper.
2 Aluminum has roughly -- there's a few 3different things that are different. One is the 4 aluminum melting point is roughly half that of copper.
5 So, 590 C versus 1090 C.
6 But, apparently, what's more important is 7 the density of aluminum is one-third that of copper.
8 And so, although your mass loss is the same, you're 9 losing triple the volume of aluminum compared to the 10 volume of copper.
11And so, you're going to see much larger 12 generation of particulates, whether they're molten 13 droplets or vaporized aluminum that then reoxidizes, 14 there will be much more volume loss of aluminum 15 compared to copper.
16 And so, what we see here is that, again, 17 we predicted quadratic dependence of volume loss, in 18 the top curve, top-right, and the bottom-right is what 19 we actually measure, essentially the same dependence 20 of volume loss of aluminum with increasing current or, 21 in this case, voltage, because of the way our 22 experiment was run.
23 But we were able to predict the amount of 24 volume loss of material, the amount of material being 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 205 ejected into the zone of influence for these droplets.
1 So, another question, going beyond this, 2 is, what are those particles, can we begin to 3characterize these? Can you press -- is there a movie 4 there? Or, it's not coming up yet?
5 Anyway, during these small-scale 6 experiments, we brought in high speed cameras that we 7 can bring in and look directly at the plasma 8 interface, with the arc roots, and look at the 9 generation of particles.
10 And there are clearly articles that are 11 tens of microns and even a nanoscale that are 12 generated during the arc itself. So, some particles 13 are melted metal that have been entrained in the edge 14 of the arc roots and ejected through an arc jet.
15 Other particles are melted and vaporized and then, 16 these subsequently reoxidize.
17 So, a couple questions we wanted to 18 answer, both at the small-scale and for field tests at 19 KEMA, are what kinds of particles are being evolved?
20What are the size of these particles? What's the 21degree of aluminum oxidation? And can we begin to 22 account for the exothermic nature of that oxidation, 23 the energy input of oxidation of aluminum?
24 We also want to see if there's a 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 206 difference of aluminum particle oxidation with 1distance from the switchgear? Is it truly insulating 2or is it conductive? And then, look at other sources 3 of energy, going into the arc fault.
4 So, if you go to the next slide, these are 5 some examples of particles that have been collected 6 during the KEMA experiments from last fall, but we see 7 similar particles in our small-scale tests, 8 essentially the same particle sizes.
9We see two kinds of particles. One 10 particle size is on the order of two to 15 microns.
11 These are metallic particles of aluminum, that show 12 evidence that they have melted, and then resolidified 13 during flight, and then have been collected.
14 So, the middle of these particles are 15 dominantly aluminum metal, you can see the dendritic 16 structures showing where they resolidified, but on the 17 surface of these, you see sort of a white decoration.
18 This is a material that is insulating on the top 19 surface.20 So, if you look at the top surface of 21 these particles, or if you look at just the background 22 of polymers or other things that are used to collect 23 particles in the field, we see that there's a dust, a 24 nanoscale dust everywhere in the test chamber.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 207 And that appears to be composed of very 1 small particles of aluminum oxide that are five to 30 2nanometers in size. So, we believe that these have 3 been vaporized, so we made aluminum vapor. Aluminum 4is not stable in oxygen. These, we believe, then, 5 have reoxidized and made nanoscale aluminum oxide 6 particles.
7So, we see two kinds of particles. We 8 haven't yet quantified exactly what fraction is melted 9 and what fraction is oxidized, but we have the samples 10 in hand and can come to that conclusion and publicize 11 that, definitely by the end of the year, if not early 12 in the fall.
13 So, we can begin to quantify what kind of 14 oxidation energy input should be present and, 15furthermore, what do these particles do? Are they 16 conductive or are they insulating?
17 We don't know the answer to that yet and 18 that's one of the goals for the test this fall, is to 19 collect the particles on a substrate, where we can 20 either use a surface probe or we can use energy tight 21 electrodes to look at, for these powder beds that are 22 collected, are they conductive or not between 23 electrodes? And if they are, if those collect on an 24 insulator, you may lose insulation resistance on that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 208 insulator going forward.
1 If you go to the next slide, we've begun 2 to look at how oxidized these particles are. We see 3 a range of degrees of oxidation.
4 What we find, again, is that for these 5 nanoscale particles, that we believe have been 6 vaporized, if you look at the aluminum to oxygen peak 7 ratios that we collect by x-ray, these appear to be 8essentially 100 percent oxidized. The aluminum to 9 oxygen ratios are three to two, so it looks like 10 Al2O3, aluminum oxide or sapphire.
11 If you look at the larger particles, these 12 particles have ranged from 25 percent to 73 percent 13oxidized, in terms of the analysis we do. We still 14 have to run that more and understand more about that, 15 but we do believe that the core of the particle is 16 still metallic, but the outer skin appears to be 17 oxidized.18 So, our goal is to be able to measure this 19 in the field, but also, ultimately, be able to predict 20 from these arcs what amount of metal is being melted, 21 what amount is being vaporized, and then, predict the 22balance of energy that's coming out from radiation 23 effects, thermal effects, and then, this oxidation 24 effect as well.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 209 So, again, our first models have been 1simple. They've been assuming a static arc, that's 2 not interacting heavily with the electrodes 3themselves. So, the gap is not changing with time.
4 Ultimately, we know we're consuming material, that a 5 gap has to increase during the arc.
6 We also haven't included magnetic field 7 effects to cause this arc to move during, especially 8at higher currents, a kiloamp and above, magnetic 9 field effects will dominate these arcs and we need to 10 include that.
11 So, we've conducted initial modeling runs, 12 using ARIA, which is our fluid code. Again, this is 13based on this idealized Lowke model. The Lowke model 14 assumes, essentially, a cylindrical arc that has the 15 same temperature across the arc diameter.
16 In the ARIA simulation, it's able to solve 17 the heat transfer exactly, so you actually get the 18 real heat distribution within the arc and, ultimately, 19 we can begin to include the copper aluminum 20 electrodes, the rates or electrode melting, removal of 21 those, and growth of the arc, as well as magnetic 22 forces in these.
23 So, for our first simulations with ARIA, 24 which is the more complicated code, this is a massive 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 210parallel processor code that can run on 100,000 1 processes, run much more complicated geometries than 2 the Lowke model, we looked at a simple cylindrical 3 arc, looked to see if it could predict accurately the 4 temperatures of the arc and the kind of radiation we 5 should expect from that.
6 So, next slide shows some of the equations 7of the ARIA model. I've got a lot more detailed 8description of it, if it's of interest. But I didn't 9 really want to go into it, but just wanted to show 10 what we include.
11 We include tracking of all the chemical 12constituents. We can include concentrations, 13 pressure, buoyancy, magnetic forces, joule heating, 14 and diffusion in these, and then, solve for the 15temperature of the arc itself. And then, that can 16 then be used to generate the radiative heat transfer 17 and the thermal heat transfer out of the arc itself.
18 If you go to the next slide, and press 19play, if it'll come up?
What this is looking at is 20the temperature of the arc, as a function of time.
21 So, this is from the center of the radius of the arc, 22going out to a one centimeter boundary. And on the Y 23 axis, the peak temperature is 7000 Kelvin and the 24outer temperature would be room temperature. So, this 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 211 is predicting the temperature profile of the arc, as 1 a function of time.
2 So, essentially, this would predict a 3 cylinder that has a 7000, roughly, Kelvin temperature 4 in the middle of the arc, decaying as a function of 5 radius to the outside of the arc, to the outer 6 boundary.7 So, if you plot this another way, if you 8 go to the next slide, this gives you roughly a 9 parabolic temperature profile, where the center of the 10 arc should be around 6500 Kelvin, and the outer part 11 of the arc, again, should be room temperature.
12 There's a discontinuity at around the 13outside of the arc, around 4000 Kelvin. So, actually, 14 there's the center of the arc, which is a very high 15 temperature, and there's an outer boundary of the arc, 16 which is around 4000 Kelvin, where the air interfaces.
17 So, we compare this to work in the 18 literature, we see that this agrees quite closely, the 19 same kinds of temperature profiles, the same 20 temperatures to within 300 degrees of what's been 21 predicted in the literature and also measured in the 22 literature for arcs.
23 If you go to the next slide, looking back 24at some of the Lowke data, we see some of the same 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 212 kinds of data, same kinds of behavior, and again, 1 temperatures of around 6000 Kelvin for the center of 2 the arc temperature for this.
3 So, we're beginning to get validation data 4compared to the literature. We also can go in 5 directly to our experiments and measure the 6 temperature of the arc itself using spectroscopy.
7 So, let's see, Caroline, are you online 8 right now?
9 MS. WINTERS: I am, can you hear me?
10MR. CLEM: We can hear you. So, do you 11 want to talk through your slides here?
12MS. WINTERS: Okay. Sure. So, to get a 13 better idea of the temperature in the arc and to be 14 able to compare the ARIA model results, not just to 15 prior simulations, but also to the small-scale 16 experiments we're seeing, we did a series of 17spectroscopy experiments. So, if you could move to 18 the next slide?
19 MR. TAYLOR: We're on Slide 29.
20MS. WINTERS: Okay. So, this is the 21 standard experimental schematic, in the top-left.
22 This is a top-down view, showing that the spectrometer 23 that was collecting this information was placed eight 24 inches away from the arc.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 213Using a laser diode and a series of 1 calming instances, we were able to take light from the 2 center of the arc whenever we initiated it and get 3measurements at a rate of 100 hertz. So, that's 4 taking a spectral profile every ten milliseconds for 5 the entire test.
6 And you can see on the right-hand side two 7 examples of the spectra that I'm talking about. So, 8I call these optical emission spectroscopy. Using one 9 set line that's collected, it goes through grating or 10 impinges upon it, and that grating will spectrally 11 disperse it of the amassed photons with a given 12wavelength. Or you can think about that wavelength as 13 equating to energy.
14 So, if you're at 300 nanometers, those 15 photons are going to be a higher energy than if you're 16at 800 nanometers. And the benefit is that species 17 like copper or nitrogen, have very specific emission 18 wavelengths. So, you can see here, we've identified 19 them as being atomic copper, we also have atomic 20 nitrogen.21And then, you've got our spectra on the 22 bottom, that was taken with similar test parameters, 23but without the metallic electrodes. One of the 24benefits of copper is that we lose very little mass 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 214 during our run.
1 So, there, you can really see those strong 2 nitrogen, molecular nitrogen, as well as molecular 3 carbon bands, and see the difference between the 4 molecular features, which are a little bit more broad 5 and those sharp atomic lines.
6 So, what does this information tell us?
7 If you go to the next slide, I will give some 8 explanation.
9 If we look at how those strong atomic 10 features, especially right now for copper, if we look 11 and ratio the intensity, so how many photons show up 12 at 800 nanometers versus how many photons show up at, 13 say, 600 nanometers, we can get a relationship based 14--15 MR. CLEM: Caroline, we're losing you a 16 little bit on your phone.
17 MS. WINTERS: Okay. Is this any better?
18 MR. CLEM: Yes, it's better.
19MS. WINTERS: Okay. So, by looking at the 20 amount of photons of a given energy, for, say, all of 21 the copper, atomic copper lines that we can identify, 22 we're able to generate measurements of temperature.
23 And we know that the copper vapor only 24 exists in the arc, because as it would transport 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 215 outside of the arc, it would rapidly cool down and it 1wouldn't emit any more. So, that gives us our 2 measurement of our arc temperature, and that's what 3 you're seeing on the left-hand figure on Slide 30.
4 So, that's a time-resolved measurement, 5 throughout an entire four-second test, showing that 6 the arc temperature does vary a little bit, but not 7 much, it sticks around 6000 to 7000 Kelvin, with a 8 positive residual, so that you understand the error 9 associated with those temperature measurements.
10 Additionally, for certain spectra, we were 11 able to get a secondary measurement of the surrounding 12 air temperature. And so, that's shown in the right-13 hand figure. And that's shown for two different arc 14 currents.15 So, so far, we've been limited in our 16 currents, although we're hoping, as Paul said, to go 17up to a kiloamp. And so, in doing so, you can see 18 here, this is the difference between 100 and 150 amps, 19 but soon, we hope to have measurements at greater than 20 that, up to a kiloamp for comparison.
21 And because it's only a small difference 22 in current right now, we see only small -- we see very 23 little difference in temperature, except that the 24 surrounding air appears to be at a lower temperature, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 216 around 4000 Kelvin, and the center of the arc is 1 holding at 6-7000 Kelvin, which is in agreement both 2 with the ARIA model that we've run at Sandia, as well 3 as the prior literature, which predicts that it should 4 be between 6200 and 7200 Kelvin.
5 We'll be continuing these experiments, not 6 just for copper electrodes, but also for the aluminum 7 electrodes, and we're working on getting measurements 8 of the aluminum arc temperature, as well as the copper 9 temperature.
10MR. CLEM: All right. So, these 11 measurements, so far, have been done on small-scale 12 experiments at Sandia and now that we've proven that 13 they work and they're valuable, we'll be using them in 14 onsite tests at KEMA this fall also, at kiloamp and 15 15 kiloamps, and I believe, on some of the other higher 16 current tests as well, maybe 25 kiloamps as well.
17 So, we think we can, again, in addition to 18 the calorimetry data and the electrical data for the 19 input, we can start to validate these models and get 20 more data about the actual arc temperatures in actual 21 HEAF events, in open box studies and potentially even 22 in enclosures, moving forward.
23 MR. MELLY: Yes, and we when say we're 24 going to be doing this testing up at KEMA, in this 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 217 upcoming round of testing, this is testing that will 1 be done in addition to the tests that were identified 2 on the test matrix.
3 These tests will be performed in an open 4 box, that we can actually visualize the arc itself.
5 These will not be the tests that we identified 6 previously on the matrix, they're additional open box 7 tests that are going to be solely used for validation 8 purposes.9 MR. RANDELOVIC: Quick question.
10 MR. CLEM: Sure.
11 MR. RANDELOVIC: So, it's going to take 12 some time to validate the model. The small-scale --
13 MS. LAFLEUR: And it's iterative.
14 MR. RANDELOVIC: -- testing -- right.
15 MS. LAFLEUR: Yes.
16 MR. RANDELOVIC: The small-scale test, I 17 mean, all that work that you have done looks good, it 18took some times. You're going to be performing 19testing at KEMA, open box testing. How long do you 20expect that effort to last? Are we going to have this 21 model ready before we start testing the actual 22 switchgear?
23 MS. LAFLEUR: In August, no.
24 MR. RANDELOVIC: Okay.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 218 MS. LAFLEUR: No.
1 MR. MELLY: It's going to be performed 2 concurrently.
3MS. LAFLEUR: But we do have plans to 4predict those tests. We'll just predict them after 5 the tests.
6 MR. RANDELOVIC: Okay.
7 MS. LAFLEUR: Yes.
8 MR. CLEM: I think we have a project plan 9 that includes, yes -- basically, it's going to be 10 predicting, if you give us a current, you tell us 11 based on a busbar, we predict blindly what should the 12energy output be from that? What should the radiative 13 energy output be?
14 And we can predict it for future tests, we 15can predict it for past tests where we haven't seen 16 the data. So, but that's the goal, is to really put 17 the model to the -- feet to the fire and see if it's 18 accurate.19 But first, we're just building up the 20 belief that we can accurately predict the evolved 21 energy with copper busbars, aluminum busbars, on 22 increase in current and capture the atmospheric 23 chemistry correctly that gives rise to the resistance.
24MR. RANDELOVIC: Okay. So, you'll be 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 219 working trying to set up the models, ARIA and FUEGO, 1calculating. Have we -- do we have any experience 2 from the past, where these codes were coupled and we 3 had --4 MS. LAFLEUR: Yes, and we can --
5 MR. RANDELOVIC:
-- successful application?
6 MS. LAFLEUR: We can skip to Matt's slides 7--8 MR. RANDELOVIC: Okay.
9 MS. LAFLEUR: -- do you want -- can we skip 10 to, I think it's 36? Matt, are you able to speak?
11 MR. HOPKINS: I think so.
12 MS. LAFLEUR: Okay, we've got you. We're 13 just advancing our slides here, to the slide that 14 starts with Sierra Mechanics.
15MR. HOPKINS: Okay. I'm only looking at 16 the slides through the online thing.
17 MR. CLEM: Okay.
18 MS. LAFLEUR: Okay.
19 MR. HOPKINS: That seems to be all right.
20 So, at Sandia, we have this Sierra Mechanics framework 21 and it's been under development, being used for about 2220 years. Two of the elements in Sierra Mechanics are 23 this ARIA code and this FUEGO code.
24 ARIA is a multi-physics transport code, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 220 with free moving boundaries and various levels of 1coupled solution techniques. So, we use it, 2 generally, for problems that have pretty tightly 3 coupled physics, complicated physics, and multi-phase 4 processes.
5 So, for example, solid electrode, molten 6 electrode, vaporized metal gas, and other gas where 7 you have temperature dependent physical parameters, 8 like conductivity, thermoconductivity and electrical 9 conductivity.
10And FUEGO is a code we've used for 11extensive fire modeling. So, if we want to determine 12 the effect of a box with material in it, while it sits 13 in a fire, FUEGO can simulate sort of the large-scale 14 convective transport, along with regular CFD as well.
15 And then, both of those codes have a sense 16of radiation transport. So, we can track the 17 transport of all of thermal and radiative ablation of 18 material, entrainment of that material to change the 19 state of the gas, all coupled together.
20And as, I think it was Gabe earlier 21 mentioned, or spoke in this direction, there are many 22 rabbit holes we could go into to get more even 23 detailed, along all of these axes. So, I think part 24 of what we're going to be developing is prioritizing 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 221 which of these particular phenomena are critical to 1 get correct and try to simplify where we don't need 2 it.3 So, ARIA and FUEGO are the key ones and if 4we go to the next slide, yes, I'd like to point out 5 that there's some question about where these codes 6 have been used in the past and what kind of coupled 7 problems they've been used on.
8 They have been coupled together, I don't 9think any of that material is presented here. One of 10 our constraints here at Sandia is a lot of the 11 extensive validation work we have has not been made 12available in the open literature. Depending on the 13 interest, we could try to find some of that material 14 and see if it can be released, but we haven't done 15 that extensively yet.
16 ARIA has been used -- so, I'm going to 17explain some problems that I think are close to the 18 kinds of things we're talking about for HEAF modeling.
19 ARIA has been used for problems such as 20laser welding. So, here, we have an intensive heat 21 source, if you will, applied to a metal and we do the 22 transient evolution of that metal, in terms of its 23 temperature, its phase change.
24 Similar questions related to punch-through 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 222of the material. So, when does the radiation, thermal 1 environment, over some period of time, get to the 2 point that it actually melts and punches through a 3 material?4 Both of these codes are massively 5 parallel, so they scale to the thousands and more than 6thousands of cores. I think I've mentioned some of 7 the rest, and I don't know if anyone in this audience 8 wants to hear more details, I can provide it now or in 9the future, but maybe skip some of the minutia here 10 and go to the next slide.
11So, on the left, you're seeing, I think 12 that's an animation, that is a, I believe a metal box 13containing an explosive material. And you see the 14 temperature release, as this front extends and you can 15 see the box deforming. So, this is just providing a 16 demonstration of the temperature dependence and the 17 free surface moving boundary portions of ARIA. Next 18 slide.19 Here's another key part of the physics 20 that I think would be new, in terms of the types of 21 approaches that have been used in the past, radiation 22 transport.
23 It's not just determining the radiation 24 incident on a material, say for use in a fragility 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 223 model, it's also that the radiation can reradiate in 1 the gas environment that it's in, especially if 2 there's soot present.
3 So, computing the power in radiation from 4 an idealized arc still isn't the whole story, that 5 radiation, some of it anyway, is absorbed by the gas, 6 smoke, and soot environments and then, reradiates.
7 So, being able to track that may be important, so we 8 have those capabilities. Next slide.
9 MS. LAFLEUR: Yes, on this slide --
10 MR. HOPKINS: Yes.
11 MS. LAFLEUR: -- Calore was the previous 12name of ARIA. Its name has evolved over time. Sorry, 13 Matt --14 MR. HOPKINS: Sort of.
15 MS. LAFLEUR: Okay.
16 MR. HOPKINS: So, here, I think Paul 17 presented a slide that introduced this already, but 18 basically, the transport equations we include are 19 conservation of mass, conservation of momentum, 20 conservation of energy.
21 And we can do multi-species models, so we 22 can have, for example, air, air ions, electrons, and 23 aluminum as different species and they can each have 24their own uplink to the rest of the system. Next 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 224slide, please. That's somebody else now, I think.
1 Oh, no, that's still me.
2 So, one of the problems that was solved in 3 the past was a safety question in a battery storage 4facility. So, if a fire broke out in this battery 5 storage facility, you'd like to understand the damage 6 to surrounding areas. So, that sounds awfully 7 familiar to what we're talking about here.
8If you go to the next slide, so on the 9 left, before you hit go, on the left are three racks 10of cells. And we've put a fire between the first and 11 second rack, so that fire is modeled as a source of 12 both radiative and thermal conductive energy.
13 And you can see, there's buoyancy effects, 14 because we have hot gas containing soot that have come 15to the ceiling of this material. And you can see, on 16 the top-right, the internal flow patterns generated by 17 the non-constant temperature around, along the edges 18 of the cabinet.
19 And on the bottom-right is something that 20 I think is right in the middle of this question of how 21 do you take an energy source model and then, use that 22 to inform a fragility model?
23 On the bottom-right is actually the heat 24 flux experienced on one of these cabinets, due to this 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 225fire. And the next slide, please. I think this is an 1 animation of the results.
2 And so, on the bottom-right, I don't 3 believe this particular model has an evolution of that 4 material, other than its temperature, but using ARIA 5 to model also the, quote, target, you can talk about 6 the phase change and eventually failure or blow-7 through of that material, in addition to using that 8same set of capabilities to simulate the electrode 9 evolution, in terms of its phase change and loss 10 ablation. Next slide, please.
11 So, this is the same system, but now we've 12 changed the environment, and we have a cross wind 13that's going at ten meters per second. So, this is 14 more to open up the set of questions you could ask if 15you wanted to change environmental conditions. I 16 don't know that winds blowing nuclear reactors is a 17 concern. Next slide, please.
18 MS. LAFLEUR: I think that's his last 19 slide.20 MR. HOPKINS: Okay.
21 MS. LAFLEUR: Yes, I think there's just a 22 question prompt at the end of yours, Matt.
23 MR. HOPKINS: Are there any questions?
24 MR. HAMBURGER: So, if anyone has questions 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 226for Matt, they can ask them now. We do have a 1 question on the webinar about the spectroscopic 2 analysis methods.
3 MS. LAFLEUR: Okay. We'll take whichever 4 questions.
5MR. HAMBURGER: Okay. I will read the 6 questions from Steve Turner, who is on the webinar.
7 And his question is this, for spectroscopy 8 measurements, can you see through the smoke in full-9 size tests?
10 In attempts to measure arc properties that 11 depends on sight, the smoke intervenes quickly, so for 12 spectroscopy methods and radiation heat measurements, 13 can you see through the smoke in long arc duration 14 full-scale tests?
15 In attempts to measure arc properties --
16it looks like it got repeated. And he also asks, are 17 you validating to three-phase arcs?
18 MS. WINTERS: So, can you guys hear me?
19 MR. HAMBURGER: Yes, we can hear you.
20 MS. WINTERS: Okay. So, to his question, 21 the first is, we have done testing with the copper and 22 aluminum, and there are two specific sets of spectral 23features. The first are sharp features, which is the 24 copper, atomic copper vapor lines that I pointed out.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 227 The second is a broad band emission 1 plateau, that I really didn't talk about, but that is 2the smoke that he's describing. That is the mist from 3that surrounding gas. And by fitting it to a gray 4 body approximation, that's how I was generating those 5 secondary temperature measurements that start around 6 4000 Kelvin.
7 To his point about the large-scale 8 testing, we have done and completed VC testing and 9 spectroscopic measurements in the field and we 10certainly see the buildup of the smoke. And that 11 smoke, as the duration goes on, for about two to four 12 seconds, you see that becoming a larger component of 13 the spectral radiation that we get.
14 Now, those sharp spectral features will 15 still exist on top of it, and that's why it's 16 important to understand your baseline, when you're 17 trying to fit those, say copper vapor atomic lines for 18temperature. And we do that through a series of 19 calibration with a Tungsten lamp, which acts as a 20 perfect repository.
21 An interesting thing that we didn't have 22 time to show on these slides, though, is that we also 23completed a series of measurements with Tungsten. And 24 when we did that, we had a heavy amount of smoke, it 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 228filled the box. And in that instance, it did 1 overwhelm spectral features signature and we were only 2 able to collect that gray body emission.
3 So, it's certainly something that we see 4 in the spectra and we can map out when it overwhelms 5 any sort of arc features you would expect.
6 MR. CLEM: So, I think, we're conducting 7 open box experiments, as Nick said, to look at the arc 8 temperature in three-phase arcs, in some KEMA tests.
9 In the full -- if you're inside a bus duct 10 or a switchgear, we would like -- it would be very 11 difficult to image the arc directly, for the full 12 duration of the arc fault, due to the smoke evolution.
13 But, yes, I think, like Caroline said, we can collect 14 spectra and then, see how much of that is the smoke, 15 how much of that is the arc itself.
16 We do have calibrated infrared cameras, 17 that were used in previous experiments at KEMA and 18we'll use in the future. And that can image, of 19 course, the cloud, the sooty cloud that's emitted once 20the breach occurs. But we may not be able to see 21 directly into the arc for the full duration of the 22 HEAF events. But it's a good question.
23 Second question was about, are we looking 24at three-phase arcs? The experiments so far have been 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 229DC arcs. We'll next be going to single-phase arcs, 1and then, three-phase arcs. So, we'll be modeling 2three-phase arcs, ultimately. There's been quite a 3 bit of work looking at how to model a three-phase arc, 4 an AC arc versus DC.
5 So, if you have a 60 hertz signal, you 6 have eight milliseconds of each polarity. For about 7 the first millisecond, the arc may not be at 8 equilibrium, but from the second millisecond to the 9 eighth millisecond, there's a stable arc resistance 10 and you can treat the arc as a circuit element for 11 those periods.
12 In a single-phase arc, people brought up, 13 several times, that at the zero-crossings, the arc may 14extinguish and then, relight over and over again. So, 15 the single-phase arcs we actually believe are going to 16 be more complicated than the three-phase arcs to model 17going forward. But we anticipate using ARIA to model 18 the three-phase arcs, ultimately.
19 MR. MELLY: Yes, and as Paul said, some of 20 the challenges with this are, the reason that we can't 21 take some of these measurements in the full-scale 22 tests that we'll be performing on the switchgear that 23 represent in-plant equipment is because we do not want 24 to alter the in-plant equipment that we'll be testing.
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 230 We do not want to open a back panel or 1 create a viewing port, because that can alter the test 2itself. So, we're not doing that in part of the 3large-scale matrix. We've added these additional 4 tests where we can have an open box arrangement, which 5 will feed back to the validation, without affecting 6 the larger test matrix tests.
7 MR. HAMBURGER: Thank you, Steve, for the 8 question, and if you have any followups, you can 9either type them or we can unmute you. Do we have any 10 other questions for the Sandia folks about their 11 modeling work? Okay. Anything else on the webinar?
12 No?13Okay. It's almost 3:55, let's take 14another 15-minute break, come back at ten after. And 15then, we have a few more slides on the fragility 16 testing component, we'll have our public comment 17 period, any closing remarks, and then, we can adjourn 18for the day. So, we'll take 15 minutes and come back 19 at ten past 4:00.
20 (Whereupon, the above-entitled matter went 21 off the record at 3:53 p.m. and resumed at 4:08 p.m.)
22MR. HAMBURGER: Okay, just a few more 23 minutes of presentation about the target fragility and 24failure criteria progress. And then, we'll open it up 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 231 for public comment.
1 MS. LAFLEUR: Okay. Thank you. This is 2 Chris LaFleur again.
3 So, one thing I wanted to stress is that 4 we are definitely treating the failure criteria 5 independent of the energy release prediction 6calculation and measurement from the HEAF. That's 7 this incident energy or the emitted energy.
8 The diagram on the left, in the blue line 9 we're seeing like a typical hydrocarbon fire with a 10 typical growth curve that we model as part of the 11traditional fire PRA. And the orange line there is 12 trying to compare the temperature or the heat release 13 rate profile of a HEAF event, and it's a much higher 14magnitude, but a much shorter duration. And the 15 duration really matters as the target or the impact on 16 the target, because it has less time to absorb that 17 energy and be damaged.
18 And so, what we want to do is determine 19 the failure criteria's characteristics of specific 20pieces of target equipment: cables, transformers, 21switchgear, other cabinets, whatever. And the Work 22 Group will be determining what those target equipment 23are that we need to evaluate or develop the failure 24criteria for, as a Work Group. And those will take in 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 232 both the severity of the adverse environment as well 1as the time that it's exposed to that. And that's the 2 vision.3 The next slide is just a review of what 4 the current failure criteria is that we deal with in 5the fire PRA all the time. And it's around 6 thermoplastic and thermoset cables, and there's both 7 the radiant heat criteria and a temperature criteria.
8There is also some empirical data. It 9doesn't go down to anything less than one minute. So, 10 obviously, in a HEAF event we're talking, the most we 11were talking about is 8 seconds. So, there's clearly 12 a need to define that failure curve down below one 13 minute and see what those other temperatures or heat 14 fluxes would be when we get down to the seconds.
15 If a HEAF event causes an ensuing fire, 16 there would be some split fraction about that 17 generating of fire, and then, that would be modeled as 18 a regular hydrocarbon fire with a typical growth rate.
19 This is just for the actual heat and the arc effluent 20 event.21 So, we are going through right now looking 22 at data from the current tests where we've got 23 temperature measurements and incident/injury 24 measurements at the 3-foot and the 6-foot range from 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 233the OECD tests and the phase 1 testing. And we're 1 going to develop some needs for testing to happen in 2 four different types of cables, and then, we're also 3 going to, within the Work Group, determine what type 4 of failure criteria would be around enclosed 5 equipment.
6 Like would we base it on the breach 7prediction for the target equipment's enclosure? And 8 we may say, if your target is breached, you have to 9fail that. There will be something in the new PRA 10 method that will tell us how to treat those, and we'll 11 use the model to define the extend of that envelope of 12 whatever that criteria is, temperature "X" or heat 13 flux "Y", wherever that is. And then, you should be 14 able to have a site-specific evaluation of predicting 15 target failure around the HEAF event.
16 That's as far as we've gotten right now, 17 where it's an active, current, open action item with 18 the Working Group.
19 And I think that's the last slide I had.
20MR. HAMBURGER: Okay. Any questions about 21 the approach we're taking towards fragility testing?
22 From anyone in the room?
23 (No response.)
24 The webinar?
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 234 (No response.)
1Okay. Well, we have a public comment 2period now. So, if anything does occur to you, you 3 can ask.4So, any other comments? About anything 5 we've discussed today for any of the presenters here 6 from the NRC, Sandia?
7 MR. AIRD: You have a comment.
8MR. HAMBURGER: All right. So, we've got 9 another question from Steve Turner, and this is about 10the IEEE 1584. It says, "You cover the IEEE 1584 11 empirical existing models and the more sophisticated 12Sandia models. Did you look at the numerous CFD 13 models using accepted and verified codes different 14 than the A3.24 model, like ANSYS or ACE, developed 15 over the last 15 years by manufacturers and Kreppy 16(phonetic)? That might be a good, middle-of-the-road 17 modeling approach. These should be considered. One 18 reason the most complete approaches have not been 19 done, as mentioned in slide 6, is that the CFD 20 approaches using an energy point source are deemed 21 adequate for manufacturers and safety evaluations." 22 I guess the question there is, have we 23 looked at what he's calling "middle-of-the-road" 24 models, like ANSYS and ACE?
25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 235MR. TAYLOR: So, no, we haven't looked at 1 ANSYS or ACE or CFD modeling.
2 MR. HAMBURGER: Okay.
3 MS. LAFLEUR: Are you familiar with it?
4MR. CLEM: I guess I'm familiar with both 5of those. I think those are both good codes as far as 6 fluid dynamics and modeling thermal heat transport, 7possibly even fire analysis. I'm not aware that 8 either of those contains the physics right now to 9 address an AC arc fault and the energy released from 10that as a function of time. If it does, it's worth 11 definitely looking into. I just haven't seen it.
12 There's just a lot of -- we're colleagues 13 with the CFD group, CFDRC, that developed that code, 14 and they do have plasma experts that work in similar 15areas. But, yes, I haven't seen exactly them address 16 this problem per se.
17MR. HAMBURGER: Okay. But he just said 18 there's a large body of work that applies to the ACR.
19 Okay. Okay, that's something we can look into.
20 Any other questions or comments?
21 (No response.)
22Okay. And just a note. When I do receive 23 the transcript, I'm going to, as I've done in the 24past, package it up with all of the updated meeting 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 236 materials and make that publicly available through our 1ADAMS system. So, that will all be publicly 2 available, I'm hoping, within the next week or two.
3 Yes, so, Mark, do you have any closing 4 comments?5MR. THAGGARD: Yes. I would just like to 6 say, first of all, I want to thank those that managed 7to hang around to the end here. I know this has been 8 a long day, but I think it's been fairly productive.
9 A couple of things I think came out of 10this morning's meeting. I think there was an 11 acknowledgment that the Working Group has made a lot 12 of progress. They seem to be working well together.
13 Also, one of the things I took away from 14 this morning's part of the meeting is an 15acknowledgment that I think most people will agree 16 that trying to develop, moving away from a one-fit-all 17model is the right way to go. So, I think any effort 18we can do in that area, I think there seemed to be 19 agreement with that.
20 I recognize, based on a lot of the 21 comments that we got this morning, that there is some 22 concern about, citizen concerns about us moving 23 forward with the testing that we're trying to do later 24this summer. I think some of the discussion we got 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 237 this afternoon I think would communicate to me one of 1 the reasons that we need to move forward with that 2testing is because we need that information. I mean, 3 part of this research effort is you've got to get 4 information to build -- you know, some information 5 builds on other information. So, we need to collect 6 the information.
7 This meeting, the discussion this 8 afternoon has focused on the mod/sim primarily. And 9 one of the reasons that we focused on that was because 10 we had gotten a lot of questions about that, I think, 11 at the prior public meeting. So, we wanted to focus 12 on that this afternoon.
13I will say that one of the things -- I 14 think Kelli raised it this morning -- the recognition 15 of the importance of getting the frequency 16information, I think we agree with that. The 17 discussion this afternoon focused on the mod/sim and 18 a lot of it on the con sequences piece of it, but we 19 recognize, also, you've got to have the frequency.
20 And I think we see that the Working Group has actually 21made a lot of progress in that area. So, I think that 22 is something positive we can take away from this.
23 Again, I would like to just say I 24 appreciate everybody taking the time to spend the day 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.(202) 234-4433WASHINGTON, D.C. 20005-3701(202) 234-4433 238with us and gave us some good feedback. And I 1 appreciate the people from Sandia coming here, taking 2 up the time, and putting a lot of effort into 3 preparing for this meeting.
4With that, that is all I have. So, I 5 think we're done.
6MR. HAMBURGER: All right. Thank you all 7very much. Thank you all very much. Thank you to 8 those who participated by webinar as well.
9 And we'll publish the materials as soon as 10 we can.11 And we'll have NRC staff escort you down.
12 Thanks.13 (Whereupon, the above-entitled matter went 14 off the record at 4:19 p.m.)
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