ML12032A051
| ML12032A051 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 01/20/2012 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| NRC-1387 | |
| Download: ML12032A051 (139) | |
Text
Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards 590th Meeting Docket Number: (n/a)
Location: Rockville, Maryland Date: Friday, January 20, 2012 Work Order No.: NRC-1387 Pages 1-93 NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers 1323 Rhode Island Avenue, N.W.
Washington, D.C. 20005 (202) 234-4433
1 1 UNITED STATES OF AMERICA 2 NUCLEAR REGULATORY COMMISSION 3 + + + + +
4 590TH MEETING 5 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 6 (ACRS) 7 + + + + +
8 FRIDAY 9 JANUARY 20, 2012 10 + + + + +
11 ROCKVILLE, MARYLAND 12 + + + + +
13 The Advisory Committee met at the Nuclear 14 Regulatory Commission, Two White Flint North, Room 15 T2B3, 11545 Rockville Pike, at 8:30 a.m., J. Sam 16 Armijo, Chairman, presiding.
17 COMMITTEE MEMBERS:
18 J. SAM ARMIJO, Chairman 19 JOHN W. STETKAR, Vice Chairman 20 HAROLD B. RAY, Member-at-Large 21 SANJOY BANERJEE, Member 22 DENNIS C. BLEY, Member 23 CHARLES H. BROWN, JR. Member 24 MICHAEL L. CORRADINI, Member 25 DANA A. POWERS, Member NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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2 1 COMMITTEE MEMBERS (CONT.)
2 JOY REMPE, Member 3 MICHAEL T. RYAN, Member 4 STEPHEN P. SCHULTZ, Member 5 WILLIAM J. SHACK, Member 6 JOHN D. SIEBER, Member 7 GORDON R. SKILLMAN, Member 8
9 NRC STAFF PRESENT:
10 DEREK WIDMAYER, Designated Federal Official 11 ALLEN HOWE, NRR/DORL 12 MEENA KHANNA, NRR/DE/EMCB 13 KAMAL MANOLY, NRR/DE 14 GERALD McCOY, R-II/DRP/RPB5 15 JOHN TSAO, NRR/DE/EPNB 16 17 ALSO PRESENT:
18 GENE GRECHECK, Dominion Energy 19 ERIC HENDRIXSON, Dominion Energy 20 DAVID SUMMERS, Dominion Energy 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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3 1 TABLE OF CONTENTS 2 Opening Remarks by the ACRS Chairman 5 3 Augmented Inspection Team Report on North 4 Anna 6 5 Adjourn 6
7 8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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4 1 P R O C E E D I N G S 2 8:30 a.m.
3 CHAIR ARMIJO: Good morning. The meeting 4 will now come to order. This is the second day of the 5 590th meeting of the Advisory Committee on Reactor 6 Safeguards. During today's meeting, the Committee 7 will consider the following: Augmented Inspection 8 Team Report on North Anna and preparation of ACRS 9 reports.
10 This meeting is being conducted in 11 accordance with the provisions of the Federal Advisory 12 Committee Act. Mr. Derek Widmayer is the Designated 13 Federal Official for the initial portion of the 14 meeting.
15 We have received no written comments or 16 requests for time to make oral statements for members 17 of the public regarding today's sessions. There will 18 be a phone bridge line. To preclude interruption of 19 the meeting, the phone will be placed on a listening 20 mode during the presentations and Committee 21 discussion.
22 A transcript of portions of the meeting is 23 being kept and it is requested that the speakers use 24 one of the microphones, identify themselves, and speak 25 with sufficient clarity and volume so that they can be NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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5 1 readily heard.
2 Now I'd like to turn the meeting over to 3 staff and I believe that would -- Dana is going to 4 leave us through that, sorry.
5 Dana?
6 MEMBER POWERS: You do it so well. Thank 7 you. This is an information briefing. I was asked to 8 prepare any documents based on this briefing. I 9 suppose if we want to, we can.
10 Most of you are aware -- what was it, 11 August 23rd -- that there was an earthquake. Those of 12 us who have experienced in California think that a 5.8 13 earthquake is not something to get too excited about, 14 that East Coast earthquakes are a little different.
15 It occurred near Mineral, Virginia, close to the North 16 Anna Nuclear Power Station. The earthquake caused 17 Units 1 and 2 to automatically shut down. There was 18 a loss of offsite power. No damage was reported to 19 the system. But it was the first instance of an 20 operating reactor exceeding its design basis 21 earthquake.
22 Consequently, there has to be a fairly 23 extensive inspection prior to restart and what we're 24 going to hear about is both what the licensee and the 25 staff have done in connection with that inspection and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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6 1 restart process.
2 To begin our discussions, I guess Allen 3 Howe is going to give us an opening statement and then 4 we will move to the licensee.
5 MR. HOWE: Thank you, and good morning.
6 I'm Allen Howe, Deputy Director, Division of Operating 7 Reactor Licensing in the Office of Nuclear Reactor 8 Regulation. We appreciate the opportunity to brief 9 the ACRS on the actions that were taken following the 10 earthquake that occurred near North Anna last August.
11 As you said, the licensee will provide an 12 overview of their activities and then that will be 13 followed by a staff presentation of the inspection and 14 technical review activities that were performed 15 following the seismic event.
16 Just very quickly, following the 17 earthquake, NRC staff did complete numerous activities 18 including an augmented inspection which evaluated the 19 licensee's performance during the event. And we also 20 conducted restart readiness inspections. In addition, 21 we completed a comprehensive technical evaluation of 22 the actions taken by the licensee to demonstrate that 23 it was acceptable the units to restart.
24 Our inspection and technical evaluations 25 covered a wide spectrum of technical disciplines and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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7 1 there was very close coordination among the 2 organizations that were involved in the review.
3 At this time, I'd like to quickly 4 introduce the staff leads for the inspection and the 5 technical review activities. To my left is Gerry 6 McCoy. He's a Branch Chief in the Division of Reactor 7 Projects in Region II and responsible for the Dominion 8 Units. Gerry led the inspection efforts on behalf of 9 Region II and he'll be speaking about the inspection 10 activities, including the AIT, the restart readiness 11 inspection and the start-up monitoring. Meena Khanna, 12 to the left of Gerry is a Branch Chief in the Office 13 of Nuclear Reactor Regulation. She led the effort on 14 technical review in the Office of NRR. She will also 15 be providing the presentation describing the technical 16 review efforts that took place during the activities 17 leading up to the restart decision. We also have 18 staff here in the audience should questions come up 19 that can provide answers to any of the technical 20 issues that may come up.
21 At this point, I'd like to turn the 22 presentation over to Mr. Gene Grecheck from Dominion.
23 MEMBER POWERS: Gene, welcome.
24 MR. GRECHECK: Thank you. Good morning.
25 As Allen said, I'm Gene Grecheck. I'm Vice President NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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8 1 of Nuclear Development for Dominion. And I've met 2 some of you in what is normally my role. I'm normally 3 in charge of our new reactor projects, North Anna III 4 in specific, but very soon after the August 23rd 5 earthquake I was asked to take leadership role in the 6 recovery and the licensing efforts to -- first to 7 determine what the extent of damage at North Anna was 8 and then to work with the NRC staff to obtain the 9 necessary restart.
10 With me, I have Eric Hendrixson. Eric is 11 the Director of Engineering at North Anna. And as a 12 matter of fact, at the time of the earthquake, he was 13 the Director of Engineering for the corporate office 14 and was in the process of transitioning out to the 15 North Anna site. So he was in a unique position, both 16 from a corporate engineering standpoint and the 17 station engineering standpoint to guide the 18 engineering efforts.
19 Also with me is David Summers over in the 20 corner. David is head of our licensing organization 21 and was our primary point of contact with the NRC 22 staff during your review.
23 So a little bit of a summary -- between 24 August 23rd and November 11th when we received 25 permission to restart the units, we devoted more than NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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9 1 100,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of effort, both in on-site inspections 2 and engineering analysis. As you can see, we spent 3 over $21 million in this process, so this was an 4 extraordinarily comprehensive and complete review of 5 the North Anna Station and its seismic response.
6 We'll talk a little bit in a few minutes about NRC-7 endorsed guidance, but we exceeded the requirements of 8 the Regulatory Guide that we published some --
9 MEMBER POWERS: Why did you feel a need to 10 exceed?
11 MR. GRECHECK: I'll get to that in a 12 moment, Dana. I think you'll see it because there's 13 a flow chart and I'll show you how we did --
14 CHAIR ARMIJO: Yes, I'd be interested to 15 see that. Does that $21 million include the cost of 16 repair of the damage?
17 MR. GRECHECK: To the extent that there 18 was repair, yes.
19 CHAIR ARMIJO: Yes, I know it was minimal.
20 I just wanted to know --
21 MR. GRECHECK: It does, but as we'll see, 22 there was very little to repair. This is mostly 23 inspection, walk downs, analysis.
24 CHAIR ARMIJO: So it wasn't any hardware 25 repair, replaced --
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10 1 MR. GRECHECK: No.
2 CHAIR ARMIJO: Thank you.
3 MR. GRECHECK: So the primary finding was 4 that there was no functional damage to any safety-5 related systems at the station.
6 Part of what we're going to talk about and 7 part of what was interesting and I think was 8 educational for all of us in this is that we are very 9 used to talking about the design basis and as was 10 pointed out North Anna was the first station in the 11 United States to exceed its design basis earthquake 12 while in operation.
13 What we found is that that terminology of 14 design basis earthquake is useful and it's useful in 15 the purpose of design. It is a necessary underpinning 16 of designing a plant to respond to a postulated event.
17 But it is not very useful in terms of determining 18 actual damage to a station after an event has 19 occurred.
20 The key factors in what caused seismic 21 damage are the acceleration which is typically what we 22 consider about the ground motion response. It's also 23 important to know what frequency that vibration is 24 occurring at and it is also very important to note how 25 long that strong motion was in place.
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11 1 Now frequency and acceleration are taken 2 into account on the typical graph and you'll see that 3 in a moment, but duration is not. So when you have an 4 actual event without knowing the duration and without 5 looking at that duration it's not possible to simply 6 say oh, I had such and such acceleration at such and 7 such a frequency and be able to directly say what 8 response I expected at the plant.
9 As I said, seismic acceleration response 10 spectra are used to conservatively design plants, but 11 don't take duration into account. But there is a 12 factor which has been in the literature for some time 13 now called cumulative absolute velocity which attempts 14 to do both. It attempts to integrate essentially the 15 energy that is imparted by the vibration over the 16 period of time that that strong motion existed and 17 then with a great deal of empirical evidence, it has 18 been correlated, the CAV values against what has been 19 observed over hundreds of earthquakes around the world 20 in terms of what actually happens when you have this 21 particular event. And we'll talk about that.
22 MEMBER BLEY: Are you going to talk about 23 that in some detail?
24 MR. GRECHECK: Yes.
25 MEMBER BLEY: Okay, I'll wait until you're NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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12 1 done then.
2 MR. GRECHECK: Well, some detail.
3 MEMBER BLEY: Let me pose my question 4 ahead of time. Maybe you can address it as you go 5 through it. For some seismic analyses associated with 6 risk assessments I've seen a lot of work looking at 7 complete time histories of the -- all these factors 8 over time and multiple cases of those to examine the 9 capability of the equipment. If you can explain how 10 well this single parameter does -- play it against 11 those kinds of detailed kind of history 12 considerations, I'd really appreciate it.
13 MR. GRECHECK: I'll try to do that. So 14 this graph here is -- first should be familiar.
15 We've seen this a lot, graphs similar to this and it 16 is also what caused the initial concern right after 17 the event after this data became available. There's 18 a number of curves on this, so let's walk through 19 them. The bottom two, there's a red line and a purple 20 line. Both of them look like a little trapezoid, 21 those are the operational basis earthquake and the 22 design basis earthquake for North Anna as described in 23 the North Anna FSAR.
24 The purple one is the design basis 25 earthquake. You can see it starts -- the axes on this NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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13 1 thing is frequency. This is a logarithmic scale and 2 frequency, runs from essentially zero to 100 hertz and 3 then the acceleration is measured as a fraction of 4 gravity on the vertical scale.
5 We also hear a lot about a number and 6 everybody wants to know what was the design basis 7 number a plant was designed to and by convention that 8 is the number anchored at 100 hertz. So it's whatever 9 the value happens to be at the far right-hand side of 10 the scale. So that purple graph you can see goes up 11 to a peak of perhaps .36 or so G and then comes down 12 and ends at .12 and so if you look at the literature 13 you'll see that North Anna 1 and 2 have a design basis 14 of .12G. So that's the first thing that when you're 15 trying to explain to the public what the design basis 16 of a plant is, and they read that it's .12G and then 17 they hear that well, at some frequency, for example, 18 that the acceleration was .4, they say well, you were 19 four times the design basis and that's not at all 20 correct because as you can see it various by 21 frequency.
22 The OBE, the operational basis earthquake, 23 is just arbitrarily set at 50 percent of the DBE, so 24 that's that lower curve.
25 The green curve up at the top represents NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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14 1 the synthesized curve for the IPEEE effort that was 2 done some years ago when the NRC staff asked all 3 plants to look at what were the -- to the ability of 4 plants to survive in events significantly larger than 5 the design basis. For North Anna that green curve 6 represents what the IPEEE looked at the North Anna 7 plants for and you can see that that is quite a bit in 8 excess of both the design basis and the blue and 9 orange lines which represent the actual measured 10 accelerations from this earthquake.
11 MEMBER CORRADINI: Gene, can you just say 12 that again? The green is what now?
13 MR. GRECHECK: The green was the basis for 14 the IPEEE review of the North Anna plants back during 15 the 1990s.
16 MEMBER CORRADINI: So it was the source 17 input to see if you'd serve the pot?
18 MR. GRECHECK: Right.
19 MEMBER BANERJEE: What was the basis on 20 which that line was constructed?
21 MR. GRECHECK: Eric, do you remember?
22 MR. HENDRIXSON: It was guidance given by 23 the NRC a number of years ago and I can't recall the 24 Reg. Guides on what to apply to the power station.
25 MEMBER BANERJEE: So it looks like it's NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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15 1 about a factor of two almost.
2 MR. GRECHECK: A little over two.
3 MR. HENDRIXSON: Two and a half.
4 MEMBER BANERJEE: Well, whatever it is, 5 but how did they arrive at that factor?
6 MR. GRECHECK: I really don't recall.
7 MEMBER CORRADINI: Can we ask the staff?
8 MEMBER BANERJEE: Yes, can we get that 9 answer. How was that curve established, the green 10 one?
11 MEMBER CORRADINI: The green one, yes. If 12 not now, eventually.
13 MEMBER BANERJEE: If not now, later.
14 MEMBER SHACK: Well, there were lots of 15 discussions in the '90s of what the seismic margin 16 should be and I think EPRI proposed one and a half.
17 The staff proposed two, maybe two and a half. And the 18 Commission came down with 1.67 as -- so my guess is 19 it's one of those floating numbers at the time.
20 MEMBER RAY: It was looking for 21 vulnerabilities that could be addressed. That was the 22 whole point of the exercise.
23 MEMBER BANERJEE: But there must be some 24 basis.
25 MEMBER CORRADINI: It's essentially two NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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16 1 and a half. I was just curious if it was just an 2 engineering judgment or if there was some technical 3 basis.
4 MEMBER POWERS: I don't know that it's two 5 and a half, Mike.
6 MEMBER CORRADINI: Based on Gene's 7 description, the red is 50 percent lower than the 8 purple and the green is 2.5 times bigger than the 9 purple --
10 MEMBER BANERJEE: On the extreme right.
11 MEMBER CORRADINI: At the extreme right.
12 MR. HENDRIXSON: And that particular 13 curve is a function of your particular strata and 14 seismic activity and analysis.
15 MEMBER CORRADINI: So the green dependent 16 on the region of the country and geology and all kinds 17 of stuff.
18 I guess what I'm asking is the purple was 19 the one that was developed on region. Everything else 20 is a scale up is the way I interpreted it.
21 CHAIR ARMIJO: We have a staff member.
22 MR. HOWE: Good morning, this is Allen 23 Howe again. And we understand the question is what 24 was the basis for the development of the curve for the 25 IPEEE. And we're looking for someone to respond to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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17 1 that question to you. So we'll take that one right 2 now and try to get back to you before the end of the 3 meeting today.
4 MR. MANOLY: This is Kamal Manoly with the 5 Division of Engineering NRR. The RLE, the Review 6 Level Earthquake, that's based on seismic margin 7 assessment that was done as part of IPEEE. In the 8 simple explanation it really reflects the capacities 9 for the safe one shutdown path and that is based on 10 the HCLFPF 95.5 percent and basically it tells you 11 that that's the kind of capacity you expect in 12 components in the one safe shutdown path. Some 13 components did not meet that review of earthquake and 14 they were evaluated independently as part of the 15 restart effort.
16 MEMBER RAY: It was the form abilities 17 identification that was the point of the exercise.
18 MEMBER POWERS: For our purposes, we can 19 let that one float. Gene, just go ahead.
20 MEMBER BANERJEE: What were the other 21 curves?
22 MR. GRECHECK: So the blue and the orange, 23 the ones that are more irregular, those were the 24 actual measured data from our seismic instrumentation 25 in the Unit 1 containment.
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18 1 MEMBER BANERJEE: So what's the orange and 2 what's the blue?
3 MR. GRECHECK: Orange is the -- we 4 measured in three directions, so east-west, north-5 south and vertical. So the orange is the east-west 6 direction and the blue is the north-south direction.
7 MEMBER CORRADINI: And where is the 8 vertical?
9 MR. GRECHECK: The vertical is not on this 10 graph. It's a different graph because actually the 11 design values are different, so I just chose to use 12 those.
13 MEMBER BANERJEE: So the purple and the 14 reds were for horizontal acceleration?
15 MR. GRECHECK: Correct. There's a similar 16 graph for vertical. I just didn't --
17 MEMBER BANERJEE: Is it the same order of 18 magnitude?
19 MR. GRECHECK: Yes.
20 MEMBER BANERJEE: It's sort of more or 21 less isotropic at acceleration, that's the assumption?
22 MR. GRECHECK: Presumption.
23 MEMBER BANERJEE: Presumption.
24 MR. GRECHECK: So a couple of things jump 25 out at you here is that certainly at some frequencies NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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19 1 the actual measured acceleration exceeded what the 2 design basis curve showed, but you can see that it was 3 enveloped by the IPEEE curve so we had this data right 4 at the beginning, so we said okay, it exceeded the 5 design basis. It was less than IPEEE so we would have 6 expected at a very, very first level that we should 7 not expect to see significant damage to the plant, but 8 this was very early.
9 A couple of other things to point out is 10 that one of the lessons that is coming out of the work 11 that has been done on East Coast earthquakes over the 12 years that is part of the central and eastern United 13 States' effort and part of the foundation for what may 14 be Generic Letter 199 is that the frequency 15 distribution of an earthquake on an East Coast 16 earthquake at least is not at all what this curve 17 predicts. You can see peaks at higher frequencies 18 typically around 20 hertz. This is what the models 19 are predicting.
20 So even with this event, we were able to 21 see these peaks at higher frequencies that previously 22 at least during the initial licensing of North Anna 1 23 and 2 were not part of the model.
24 Any other questions on this graph?
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20 1 about the actual event. Here again, we're looking at 2 accelerations in the three directions, east-west, 3 vertical, and north-south. This is an actual time 4 history of the event as measured. The shaded area 5 represents the design basis acceleration. And so you 6 can see that right at the beginning of the event, at 7 about two seconds into the event, we had a peak 8 acceleration, but that peak acceleration was very 9 short. The numbers on the side, you can east-west, 10 the 3.1 seconds, 1.5, and 1.0, that is the definition 11 of strong motion which I think represents 70 percent 12 of all the energy was released during that period.
13 That's a standard definition of strong motion.
14 You can see that that strong motion 15 essentially was something between one and three 16 seconds. And the actual peaks, for example, in the 17 north-south direction you can see some very, very 18 sharp peaks that exceed the design basis level, but 19 there's essentially one point there. So what you had 20 was a single event where something had a single sharp 21 acceleration, but then for the vast majority of this 22 event was essentially background.
23 This surprises many people because, for 24 example, my office is at our Innsbruck office about 40 25 miles from the plant and I felt this event and it was NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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21 1 a long time. I mean you stood there and you were very 2 much aware of the fact that something was happening.
3 But the thing that struck me after I saw this is that 4 by the time you were aware that something was 5 happening, the event was over, the event of 6 significance. So for 20 or 30 seconds or so you felt 7 vibration, but the strong motion was long gone by the 8 time that you were even aware that something had 9 really happened because it was a very, very short 10 event in terms of strong motion.
11 MEMBER CORRADINI: And that's a definition 12 that the staff uses as part of licensing or is that 13 something more scientifically --
14 MR. GRECHECK: It's not part of the 15 license. The license is based on the design spectrum 16 which is what we were talking about before.
17 MEMBER CORRADINI: So this is just 18 analyzing --
19 MR. GRECHECK: This is analyzing actual 20 measures --
21 MEMBER CORRADINI: That's the definition.
22 If somebody said what is strong motion -- okay.
23 MEMBER POWERS: So one of the problems of 24 our design basis evaluation is just what Gene brought 25 up is we do frequency and acceleration. We don't do NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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22 1 duration. And that's something for us to think about.
2 MR. GRECHECK: Now for the purpose of 3 design, a duration has to be assumed and depending, 4 for example, if you're going to do a shaker table 5 test, and you have to shake it for some period of time 6 and typically those times are in the 30-second range 7 or so. So what you do is you shake your test object 8 at the maximum design acceleration for that entire 9 time period. So there is a duration that is part of 10 the design effort, but that duration is a very long 11 duration and so you can't say it has nothing to do 12 with duration. But the thing is is that in order to 13 be able to say how does what actually happen compare 14 to what I tested for, what I designed for, you need to 15 look at duration and that is not -- that's not part of 16 the quoted design basis.
17 MEMBER POWERS: We have very long 18 durations in Pacific Rim earthquakes.
19 MR. GRECHECK: Yes.
20 MEMBER POWERS: Thirty seconds is not a 21 long time for the Pacific Rim. Again, it's a function 22 of where you are and what the geology -- do you know 23 what geological source the earthquake was from?
24 MR. GRECHECK: No, not specifically.
25 There is no identified -- as I said, two is not NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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23 1 uncommon.
2 (Laughter.)
3 MR. GRECHECK: There's no identified 4 seismic fault or anything that this was identified 5 with. And again, I'm getting off into non-scientific 6 things here, but in general, what I understand about 7 East Coast events is that, of course, there are no 8 tectonic, active tectonic plates on the East Coast, 9 but there were a long time ago. And the seismic 10 event, the action that created say the Appalachian 11 Mountains way, way back left a lot of residual stress 12 in the rock. And what we're seeing is just this 13 relieving of residual stress somewhere in the rock 14 that is there. But there's no identified feature 15 that's associated with that.
16 MEMBER CORRADINI: But Dana said something 17 I didn't hear. So Dana, your point was the 30 seconds 18 is an assumed and that given historical things could 19 be considered short or long.
20 MEMBER POWERS: Depends on where you are 21 and what kind of earthquake you have.
22 MEMBER CORRADINI: But from a testing 23 standpoint that's a pretty typical order of magnitude 24 that people test at.
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24 1 with shaker table to tell you a definitive answer.
2 MEMBER CORRADINI: I just didn't hear what 3 you said.
4 MEMBER BLEY: I think that's correct.
5 That's about right.
6 MEMBER RAY: They go as long as 45 7 seconds. I did a shaker table.
8 MR. GRECHECK: Certainly for our testing 9 that we were able to go back and look at, but that's 10 the time frame.
11 So to put this cumulative absolute 12 velocity in some perspective, the blue bars on this 13 graph represent the calculated CAVs for the three 14 directions for the North Anna event. The cumulative 15 absolute velocity, if you calculated one for the 16 design basis, would be the yellow bars. And the green 17 bars represent again a calculated CAV if you assumed 18 the IPEEE event over the time period.
19 So --
20 MEMBER BANERJEE: And the yellow and the 21 green are integrated over 30 seconds?
22 MR. GRECHECK: Yes.
23 MEMBER BANERJEE: And the other one is --
24 MR. GRECHECK: -- what we measured.
25 CHAIR ARMIJO: So it's the negative NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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25 1 acceleration and the positive acceleration are all --
2 MR. GRECHECK: It's all integrated.
3 MEMBER CORRADINI: So it's the absolute --
4 MEMBER RAY: Does the licensing basis give 5 you the duration that you use here for the DVE, the 6 yellow bar?
7 MR. GRECHECK: Yes, well, it does in the 8 embedded Reg. Guides that are subtiered to the higher 9 level.
10 MEMBER RAY: But I would suppose those 11 post-date North Anna's design, don't they?
12 MR. GRECHECK: Probably not. I think 13 probably some of this was already there.
14 MEMBER CORRADINI: I didn't understand 15 your question. Are you talking about the black line 16 or the yellow --
17 MEMBER RAY: The yellow line. I just 18 wondered where they got the duration from because my 19 experience is those durations that they would have 20 used came after North Anna was licensed.
21 MR. GRECHECK: There had to be a basis for 22 the testing that was done for the North Anna equipment 23 which, like I said, was in that 30-second range. So 24 I'm assuming there was some regulatory basis.
25 MEMBER RAY: Yes. That's fine.
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26 1 MR. GRECHECK: There's a line here called 2 the regulatory limit and that number is extracted out 3 of the Reg. Guide that was issued and we'll talk about 4 that Reg. Guide in a few minutes. That Reg. Guide 5 specified a level of .16 as a cumulative absolute 6 velocity number. And that Reg. Guide is based on EPRI 7 document. And the EPRI document says that if you show 8 that it was .16, then you're using this empirical 9 evidence that I was mentioning before where they 10 looked at all of these earthquakes, hundreds of 11 earthquakes around the world.
12 It was stated that no observed structural 13 damage had ever been seen to an engineered structure 14 at that level. So you have a very, very high 15 confidence that you're not going to see damage 16 certainly to a seismically-designed structure when 17 what they call a commercially-designed structure had 18 never seen any damage at that level.
19 Now there's a number of CAV limits out 20 there that are talked about. The .16 value was 21 specified by the staff when they endorsed the EPRI 22 document. EPRI had originally proposed a value of 23 .3,looking at a longer event. The staff had some 24 questions about that so they limited the scope of the 25 event and said well, with a shorter time period we're NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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27 1 going to use .16.
2 In our conversations with EPRI subsequent 3 to this event, they're saying that our time history 4 looks more like what they were thinking about in terms 5 when they specified this .3 number. And so from their 6 perspective, the more appropriate number --
7 MEMBER SHACK: I thought the .16 was also 8 based on a filtering that you threw out accelerations 9 that were too low.
10 MR. GRECHECK: That's correct, yes. Too 11 low over a --
12 MEMBER SHACK: Point three --
13 MR. GRECHECK: Had all of that.
14 MEMBER SHACK: Had everything.
15 MR. GRECHECK: But if you looked at our 16 entire event and you looked at all of that low --
17 MEMBER SHACK: I guess that was my 18 question, was yours computed with the filtering?
19 MR. GRECHECK: This was. What you see 20 here was calculated with the filtering and was 21 compared against the .16 value.
22 The reason I bring that up is because it 23 is --
24 MEMBER BANERJEE: The filtering is a 25 threshold?
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28 1 MR. GRECHECK: It's a threshold.
2 MR. HENDRIXSON: The way it works is you 3 calculate, integrate over all the time the absolute 4 value and you exclude the tail end if over a duration 5 of one second all the vibrations were less than 6 0.025Gs. So you have to go whole second with less 7 than 0.025Gs.
8 CHAIR ARMIJO: If you didn't have the 9 filtering, how much greater would the regulatory limit 10 be in your --
11 MR. HENDRIXSON: About .23 for the worst 12 vibration which was the north-south which is the one 13 on the furthest --
14 MEMBER CORRADINI: So the blue would have 15 gone from whatever it is to about .23?
16 MR. GRECHECK: It would have gone from .17 17 to about .23.
18 MEMBER CORRADINI: And when you do the 19 filtering, you do it with the yellow and the green.
20 You did it just with the actual data?
21 MR. HENDRIXSON: Correct.
22 MR. GRECHECK: But again, that .23 would 23 be compared against a .3. Why is that comparison 24 important? Because the Reg. Guide basically states 25 that if you are below that limit, then by definition NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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29 1 you have not exceeded the OBE. Not the BBE, the OBE.
2 By definition, you have not exceeded the OBE. So in 3 the case that we were having here, we barely exceed 4 the OBE value in one direction and that's what led to 5 this entire discussion.
6 MEMBER BANERJEE: Now when you talk about 7 this, maybe you perhaps clarify. You said that no 8 seismically-designed structure had failed below this?
9 MR. GRECHECK: No commercially --
10 MEMBER BANERJEE: Or no commercially --
11 MR. GRECHECK: No commercially-designed 12 structure had failed above -- below .16.
13 MEMBER BANERJEE: Below .16. So a 14 building which has been designed to normal building 15 codes would survive this?
16 MR. GRECHECK: Yes, without structural 17 damage. You would have cosmetic damage, but you would 18 not have structural damage. And it has never been 19 observed. So it's with all of this data. The attempt 20 was to be able to come up with an empirical, 21 predictive value to say I can measure this very 22 quickly. You can measure this within an hour or so 23 after the event. You know what the CAV number was, 24 and you can immediately predict what you expect to be 25 able to find.
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30 1 MEMBER BLEY: Gene, you just said 2 something that I can't been aware of. I thought the 3 focus came from Figure 4 with the spectra showing the 4 frequencies at which you exceeded. And you just said 5 that it was the CAV point here where you exceeded it 6 that really set this off. So can you clarify a little 7 bit?
8 MR. GRECHECK: Okay, from a legal 9 standpoint --
10 MEMBER BLEY: Yes.
11 MR. GRECHECK: The regulations state that 12 if you exceed the design basis, then you have to prove 13 and I think Part 100 has some words in it that you 14 have to prove that no functional damage occurred.
15 MEMBER BLEY: And those words are based on 16 the spectra?
17 MR. GRECHECK: They are.
18 MEMBER BLEY: Okay.
19 MR. GRECHECK: However, the words are in 20 the Reg. Guide that says that if you're below .16 then 21 you have not exceeded the OBE.
22 MEMBER BLEY: I didn't know that was there 23 or not.
24 MR. GRECHECK: It's not easy to reconcile.
25 MEMBER BLEY: Maybe we can ask the staff.
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31 1 (Laughter.)
2 MR. GRECHECK: But I am pointing out that 3 that statement is there and I think that our -- it 4 would have been a different exercise perhaps if this 5 value had been 10 percent lower.
6 MEMBER BANERJEE: Is there a scientific 7 basis for this? Because essentially it's a velocity.
8 It's not an energy, right? So what is the scientific 9 basis of using that, rather than some form of an 10 energy spectra?
11 MEMBER CORRADINI: It's not a velocity.
12 It's an impulse.
13 MEMBER BANERJEE: It's a velocity.
14 MEMBER CORRADINI: If there's some fixed 15 mass that's being whipped around like this, it's an 16 impulse.
17 MEMBER BANERJEE: Well, under repeated 18 forcing. But eventually it's the velocity, that's 19 what it is.
20 MEMBER CORRADINI: Perhaps.
21 MEMBER SHACK: You have acceleration, you 22 get a velocity.
23 MR. GRECHECK: And I think that's why the 24 term is in there, but again, I don't -- it is a weird 25 criterion --
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32 1 MEMBER BANERJEE: I can't see any obvious 2 scientific basis for it. There must be some.
3 MR. GRECHECK: If you read the EPRI 4 document, they do say it's empirical. It is not some 5 sort of fundamental value.
6 MEMBER CORRADINI: I mean, if it's an 7 impulse, you can make it look like an energy if you 8 put your mind to it.
9 MEMBER BANERJEE: No, you can't. You have 10 to square the velocity.
11 MR. HENDRIXSON: I believe the basis is 12 the amount of -- the time it takes and the amount of 13 energy it takes to start a structure into a harmonic 14 when you can start causing damage. So if it's a short 15 pulse, then your entire systems and structures won't 16 start moving in a harmonic and causing damage to those 17 structures. So time is of interest, as well as the 18 magnitude of the acceleration. And if you integrate 19 that over time, that gives you a feel for how much 20 energy the structures are beginning to display.
21 And the .16 or .3, depending upon how one 22 calculates CAV is based on going out and looking at 23 engineered, non-nuclear, non-safety related, but 24 engineered structures and how they behaved for various 25 earthquakes. For the most part in the Pacific Basin NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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33 1 is where most of the data is from.
2 MR. GRECHECK: All right, I'm going to 3 move ahead and there was significant design margin.
4 We knew a lot of margin existed in the plant before we 5 started, but this is just some of the examples of 6 that. So the plant told the story. So here's all the 7 analytical things. The analytics told us we should be 8 in good shape. We don't really expect to see very 9 much, but let's go and look.
10 So here's the first example. This is from 11 the turbine building. This is on the turbine deck.
12 The turbine building is a non-seismic structure at 13 North Anna. This is on the top floor. As you know, 14 as you go up in elevation, the accelerations are 15 magnified and you get higher effects. There are these 16 demineralizer tanks to give you a sense of the scale.
17 You can see a man standing next to one of them, so 18 these are pretty tall tanks, high center of gravity, 19 high center of mass. They are supported on some 20 relatively spindly angle iron supports that you can 21 see there.
22 And on the right-hand picture is a 23 magnified view of the bottom of one of them. This 24 represents the most serious structural damage that was 25 seen at North Anna.
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34 1 MEMBER POWERS: This was it?
2 MR. GRECHECK: This is it. I had a New 3 York Times reporter, Matt Wald, who came to the site 4 about a week after the event, and he had a photograph 5 with him. The photographer was looking forward to 6 being able to take Pulitzer Prize winning pictures of 7 the damage. And he was very disappointed when I 8 pointed to this and said that's it.
9 MEMBER BANERJEE: Was he able to spin this 10 into some horror story?
11 MR. GRECHECK: Actually, it was a very 12 positive story.
13 MEMBER SHACK: Is this 12 inches by 12 14 inches, this pedestal?
15 MR. HENDRIXSON: I believe it's a 6 by 6 16 pedestal, and 3 by 3 web steel above it.
17 MR. GRECHECK: And so clearly, there was 18 movement and there was some spalling of the corner of 19 the concrete here, but this is it.
20 The next represents what was reported in 21 Bloomburg this day as a crack in the North Anna 22 containment wall. This is an interior wall. And the 23 crack that you can see running horizontally across the 24 top of the picture is a crack in grout across two 25 pored concrete slabs. This was simply a grout that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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35 1 was placed during construction, but you could paint 2 the wall. The grout did crack along -- a pretty long 3 distance, probably maybe 20 feet or so, a horizontal 4 distance. But this was not structural. It was not in 5 the concrete. It was in the grout.
6 MEMBER BANERJEE: How did Bloomburg News 7 report this?
8 MR. GRECHECK: It was reported as a crack 9 discovered in North Anna containment wall.
10 Finally, we have dry-cask storage at North 11 Anna and these are -- at least partially, are these 12 vertical casks that you can see in the upper picture.
13 A few days after the event, we did go out to the pad 14 to look and saw evidence that the casks had actually 15 moved. You can see there's a ring there on the 16 concrete. That's where the cask had been originally.
17 That's about four and a half inches or so of 18 horizontal displacement. These casks are about 100 19 tons, but they're not restrained in any way. They're 20 just sitting on the pad.
21 Your first glance is oh, why did this 22 move? But again, you're talking about a smooth bottom 23 tank on a concrete -- relatively smooth concrete pad.
24 The pad itself is seismically designed. The pad 25 didn't see any damage. The casks are monitored for NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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36 1 leakage across their seal. There was nothing detected 2 there. But it did actually --
3 MEMBER SKILLMAN: How many of the casks 4 moved?
5 MR. GRECHECK: Out of the 27 casks there, 6 I think 24.
7 MR. HENDRIXSON: All but two.
8 MR. GRECHECK: Two or three.
9 MR. HENDRIXSON: Four and a half inches 10 was the maximum, somewhere --
11 CHAIR ARMIJO: And they all moved semi-12 uniformly or did they vary?
13 MR. GRECHECK: It was just -- the example 14 that a lot of people have given us, some of us will 15 remember the old football games where you had the 16 vibrating table. That's exactly what happened.
17 MEMBER SKILLMAN: I'd like to go back to 18 your first slide, 9 here, please. Four years ago, NRC 19 published Reg. Guides 148, 160, and 161. And that was 20 the industry's introduction to active seismic. And as 21 Harold said, you could shaker table at 45 seconds and 22 people made their way to Alabama to use the shaker 23 tables down there.
24 One of the tricks we all learned was we 25 had a component with a high natural frequency and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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37 1 you'll find those tanks have a very high natural 2 frequency. The way you protected them was by putting 3 them on spindly legs. And if you could drop below 4 three or above 30 hertz, you could actually make the 5 large components become insulated from the ground 6 motion and they wouldn't dance.
7 I would just offer what you see there on 8 that connection which is the angle iron to the floor 9 is how the concrete reacted to the bending that came 10 down from a large overburden from the high mass above 11 it. But what we did for all the NSSSs is try to go to 12 either extremely strong structures or extremely 13 fragile legs that would let the ground motion move 14 under the components. And it appears as though a 15 number of these images that you've shown identify 16 components that have effectively been insulated from 17 the ground motion because the legs are so spindly and 18 those took the movement. But I believe that that's 19 what we're seeing here.
20 MEMBER STETKAR: Gene, did you see any in-21 plant electrical effects?
22 MR. GRECHECK: No.
23 MEMBER STETKAR: Does North Anna have 24 still pretty much old style relays or have they been 25 replaced with solid state --
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38 1 MR. GRECHECK: It's been replaced. It has 2 the original Westinghouse solid state protection 3 system that was --
4 MEMBER STETKAR: Okay, so your protection 5 system is solid state. What about switch gear and 6 stuff?
7 MR. HENDRIXSON: It's a combination of 8 both technologies. Relays and lots of solid state 9 devices.
10 MEMBER STETKAR: Are the relays that you 11 still have pretty small light-weight relays?
12 MR. HENDRIXSON: A combination of both --
13 I call them the ice cube relays as well as the 14 Westinghouse.
15 MEMBER STETKAR: Your peaks are kind of 15 16 and 30 hertz or so. Thanks.
17 MR. GRECHECK: All right, regulatory 18 guidance. We talked about this a little bit, but 19 we'll talk now about the process that we went through 20 to determine what we needed to do at the plant post-21 event.
22 Again, the EPRI during the 1980s developed 23 NP-6695 with guidelines for nuclear plant response to 24 an earthquake. It was an excellent document, about a 25 100-page manual essentially. You open it at the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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39 1 beginning and you follow it. It was an excellent 2 document for the case we had.
3 We have been working with EPRI now to 4 provide them some OE on this and I think they're going 5 to make some changes to it based on some of the 6 experience because again, this was the first time we 7 were able to place this document into actual use at an 8 operating plant.
9 During the 1990s, the staff endorsed this 10 document in two Reg. Guides, 1.166, Pre-Earthquake 11 Planning and Immediate Actions Post-Earthquake; and 12 then the 1.167 which was really the most useful one, 13 Restart of the Plant Shutdown by a Seismic Event. And 14 for the most part with some very, very minor 15 exceptions endorse the use of the EPRI document.
16 All right, so if you go into the EPRI 17 document, I'm going to show you two flow charts that 18 basically take you through what EPRI says you should 19 do post-event. So here's the immediate actions. We 20 start up at the top. You feel the earthquake. Does 21 the plant trip or not? Again, contrary to, for 22 example, this is not -- these are not the Japanese 23 units. There are no seismic trips in this plant.
24 There are no seismic sensors that can cause a reactor 25 trip. So a reactor trip will be caused by some thing NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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40 1 that is a result of the vibratory motion.
2 In North Anna's case, the plant tripped on 3 a negative rate flux, nuclear instrumentation trip and 4 we could get into a lengthy discussion about that --
5 MEMBER STETKAR: You dropped rods.
6 MR. GRECHECK: We did not drop rods.
7 MEMBER STETKAR: You didn't drop rods?
8 MR. GRECHECK: We did not drop rods, but 9 we had differences occurring because of the vibration 10 of both the core internals and the water inside the 11 core were causing differences between the NIs on the 12 four sides. And the NIs interpreted that as a 13 negative flux.
14 Interestingly enough, the two units 15 tripped simultaneously and they both tripped on the 16 same two NIs showing the same differential.
17 CHAIR ARMIJO: Very interesting.
18 MEMBER BLEY: You have no seismic trips?
19 MR. GRECHECK: We have no --
20 MEMBER SKILLMAN: All of your NIs were 21 operating?
22 MR. GRECHECK: All of the NIs were 23 operating and both units saw the exact same 24 accelerations in the same direction and the same two 25 NIs saw the same --
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41 1 MEMBER SKILLMAN: That's remarkable.
2 CHAIR ARMIJO: Is there anyone following 3 up on that to really nail it down on the cause and 4 explain it?
5 MR. HENDRIXSON: Yes, we actually went 6 through a detailed root cause evaluation which is 7 docketed. It goes through the various things that can 8 create that trip.
9 MEMBER STETKAR: That's the first 10 indication is you got from those two channels.
11 MR. GRECHECK: That's what tripped the 12 plant. Within a second or so of that --
13 MEMBER RAY: Excuse me, before you go on, 14 have you yet had a chance to reconcile that with the 15 impression one would have had from the CAV numbers you 16 put up there? In other words, you'd think this had to 17 propagate all the way down into the core internals and 18 so on, would have perhaps required a longer duration 19 event.
20 MR. GRECHECK: No, because we -- actually, 21 we were fortunate that we have some very high 22 resolution records on these NIs. They had a very, 23 very short time slice. And you can see the seismic 24 wave propagating through 25 the core at the time where it came NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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42 1 through. It's a pretty interesting graph to look --
2 MEMBER RAY: The thing that's interesting 3 at this point in my mind is just that there's a lot of 4 damping and so on that has to be overcome and I would 5 have thought it required more duration. But that's 6 fine.
7 MR. GRECHECK: It's a very short event.
8 It comes and goes. The oscillations stop very 9 quickly, but by that time you've already met the trip 10 and --
11 MEMBER RAY: There's a huge amount of 12 damping involved. So as soon as the excitation is 13 removed, it will stop like that.
14 MEMBER SKILLMAN: What consideration did 15 you give to relative motion inside the reactor vessel 16 of the reactor internals against the reactor vessel 17 bumpers or core catcher?
18 MR. GRECHECK: It was looked at and it was 19 inspected.
20 MEMBER SKILLMAN: And evaluated?
21 MR. GRECHECK: And evaluated.
22 MEMBER SKILLMAN: Thank you.
23 MR. GRECHECK: Just to follow up on the 24 question about -- what the operators were aware of as 25 this occurred was not so much what they were aware is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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43 1 that about a second later we lost offsite power 2 because our over-pressure protection relays in our 3 transformers picked up the vibration, saw that as a 4 sudden pressure in the transformer, and tripped the 5 transformers offline. So about a second after the 6 reactor trip, we lost offsite power.
7 MEMBER CORRADINI: So regardless of the 8 source of all this --
9 MR. GRECHECK: We would have tripped 10 anyway.
11 MEMBER CORRADINI: I guess I wanted to ask 12 it differently. In terms of -- if the first event 13 didn't cause the trip, when you do some sort of 14 analysis, what do you think would cause the trip? The 15 offsite would have been the one you would have judged 16 would be the first thing that would have sensed it?
17 MR. GRECHECK: As a matter of fact, we 18 believe that was -- the initial response.
19 MEMBER CORRADINI: Initially, that's what 20 you thought was causing it until you investigated it 21 further.
22 MR. HENDRIXSON: The turbine trip was the 23 loss of offsite power. The reactor trip was the NIs.
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44 1 didn't get to the reactor protection before the NI.
2 MEMBER SKILLMAN: In this case, were the 3 sudden pressure switches your friend or your enemy?
4 MR. GRECHECK: Well, in this case, I think 5 they were our enemy, but you don't want to lose sudden 6 pressure protection either because they're there to 7 protect the transformer.
8 MEMBER SKILLMAN: Some units have gotten 9 rid of them.
10 MEMBER STETKAR: Did you see any damage to 11 insulators out in the switchyard, ceramic insulators?
12 MR. GRECHECK: There was some.
13 MR. HENDRIXSON: The real damage wasn't to 14 the insulators themselves, the ceramic. They moved, 15 they rocked and they -- I don't want to say broke the 16 seal, but the rubber seal, a gap was made and oil came 17 out.
18 MEMBER STETKAR: On the transformers?
19 MR. HENDRIXSON: On the transformers 20 themselves.
21 MEMBER STETKAR: Without break?
22 MR. HENDRIXSON: So they were still 23 intact, but we lost some oil as a result of that and 24 had to obviously reset the seals.
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45 1 question in terms of the switchyard itself when they 2 did --
3 MEMBER STETKAR: The switchyard itself --
4 MR. HENDRIXSON: There was some damage.
5 There was some damage.
6 MEMBER SIEBER: What's the kV of the 7 switchyard?
8 MR. HENDRIXSON: It's 500, 345, and 230.
9 MEMBER SIEBER: So they're pretty big?
10 MR. HENDRIXSON: Yes.
11 MR. GRECHECK: All right, so following 12 this flow chart, you take the immediate operator 13 actions. You do operator walkdowns, and then the next 14 gate that you have to decide is did you exceed the OBE 15 or not? Obviously, we concluded that we did, so you 16 move to the next chart.
17 Here's where the differentiation occurred.
18 The blue on the left is where you start. And EPRI has 19 some definitions in their document about different 20 levels of intensity of damage. They go from zero to 21 three. Three is essentially catastrophic, you know, 22 massive structural damage. Zero has a number of 23 definitions, but basically says nothing significant 24 found.
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46 1 make that determination very quickly. So very, very 2 quickly, we did walk down the plant. We said we're in 3 a zero case. And if you follow the chart for zero, 4 you can -- you go down in that area and say do you see 5 any damage to safety-related equipment? No. Do you 6 see any damage to earthquake damage indicators which 7 are the most susceptible equipment in the plant? No.
8 And you're done. You do your surveillance tests and 9 you start up the plant. That's pretty much the path.
10 MEMBER CORRADINI: The second diamond, 11 damaged earthquake damage indicators, does that mean 12 there's actually instrumentation on --
13 MR. GRECHECK: You have equipment which 14 you have evaluated previously as being most 15 susceptible.
16 MEMBER CORRADINI: So some pre-analysis 17 says go look here, there, okay.
18 MR. GRECHECK: As a matter of fact, we 19 were talking about the IPEEE before. When you did the 20 IPEEE walkdowns, there were certain equipment that did 21 not -- you could not demonstrate 100 percent 22 confidence that they would survive that higher event.
23 So you know that these are the ones that are going to 24 be most susceptible.
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47 1 look.
2 MR. GRECHECK: That's where you go look.
3 MEMBER CORRADINI: Visual inspection, 4 okay.
5 MR. GRECHECK: So if you followed this 6 flow chart for a damage intensity zero event, then 7 this is essentially what you would do. This is a 8 relatively short inspection. It doesn't take a great 9 deal of effort. But this is what the EPRI document 10 suggests is necessary for an intensity zero or damage 11 intensity zero event.
12 However, if you evaluate it as being one, 13 two, or three, then you go off on to the right-hand 14 side. So what we did is we, just from the beginning, 15 we just arbitrarily said let's assume we're in a Level 16 1. And that's what leads to this expanded inspection 17 so everything else that you're going to hear about 18 today, from us and from what the staff described is 19 this expanded inspection effort where we just looked 20 at everything we could think of and to verify that 21 there was no damage.
22 MEMBER BLEY: Dana asked you in the 23 beginning why you went beyond NRC requirement and you 24 just again said you did. You haven't yet told us what 25 led you to do that?
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48 1 MR. GRECHECK: We did because we wanted --
2 again, this is the first time this has ever happened 3 and we believed that for ourselves and anticipating 4 what the staff would need, we decided that we needed 5 more evidence than what this would suggest we would 6 have derived.
7 Remember, for us, again, we were in the 8 same mindset as everyone else. We exceeded our design 9 basis. We didn't see anything. But we had no prior 10 experience with this and we're saying what do we need 11 to do to prove to ourselves, even not considering what 12 the staff's questions were going to be, that we don't 13 have any damage. And so we decided to do a Level 1 14 inspection.
15 So again, we went beyond this 16 classification. We started providing the staff, I 17 think about -- the event occurred on August 23rd. On 18 September 7th we met with the staff, provided the plan 19 of what we were going to do to discuss this process.
20 Of course we, at that time, said that we had several 21 weeks of inspections ahead of us before we were going 22 to be done, but we presented that all to the staff and 23 said here's what we're intending to do.
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49 1 see, we got about 130 requests for additional 2 information, in many cases asking us for inspections 3 and analyses beyond even what we had originally 4 proposed and in many cases we did those. The staff 5 will talk to you about the inspection teams and we've 6 already talked about the root cause evaluation. All 7 of this was part of this overall effort to get ready 8 to restart the plant.
9 I'll give you a few more pictures and then 10 we'll be done. Part of the inspection was to go look 11 again, as we just talked about, where -- if we were 12 going to find damage, where would you expect to find 13 it?
14 This is a picture of the Unit 2 15 circulating water tunnel. This is a picture that 16 you're not going to often see because normally there's 17 hundreds of millions of gallons a minute traveling 18 through here. But this is basically a horizontal 19 concrete box that is underground. Again, if there was 20 going to be lateral motion you would see it here 21 because you've got this rectangular box here that 22 would be susceptible to damage. There was no damage 23 found in this tunnel. But we did take the opportunity 24 of the outage to be able to go in here and do a very 25 extensive inspection of this tunnel.
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50 1 MEMBER SKILLMAN: Did you have to clean 2 this before you could make these images?
3 MR. GRECHECK: Actually, if you see the 4 white spaces there, that's the cleaning that we did 5 for detailed inspections. That's what it looks like 6 without cleaning for the majority of the wall.
7 MEMBER SKILLMAN: So it was not filled 8 with slime and mussels and mud?
9 MR. GRECHECK: No.
10 MEMBER SKILLMAN: Thank you.
11 MR. GRECHECK: They had both units down.
12 Unit 2 was scheduled for refueling -- a refueling 13 outage about three weeks after the event, so we 14 entered into the refueling outage early, defueled the 15 Unit 2 reactor, looked at all the fuel assemblies as 16 they came out. Looked at fuel assemblies in the spent 17 fuel pool. Looked at new fuel assemblies which had 18 been delivered to the site in anticipation of the 19 refueling. Did not see any fuel damage.
20 Buried piping, there was a lot of 21 speculation again about what could be in buried 22 piping. The picture that you see on the left here is 23 a transition. It is very close to the safeguards 24 building. It's a transition between several buildings 25 and again, if you were going to have buried piping NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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51 1 damage, you would expect it to be in these relatively 2 short transitions between buildings. If the buildings 3 were going to be moving, this is where you expect high 4 stress locations to be. This is maybe what, ten feet 5 down or so?
6 MR. HENDRIXSON: Yes, I'd say more like 7 six or eight feet.
8 MR. GRECHECK: But anyway, we excavated 9 all the way down there to look at these locations 10 where we would have expected to see damage. Again, 11 did not see any damage to any of this.
12 CHAIR ARMIJO: Is that buried piping 13 inspection called for if you're under the EPRI damage 14 1 category or is that --
15 MR. GRECHECK: I don't believe so.
16 CHAIR ARMIJO: So you actually went beyond 17 the EPRI 1.
18 MEMBER SIEBER: Do you have a way to 19 measure differential movement between buildings?
20 MR. HENDRIXSON: Yes. There's a survey 21 that we do and there's survey markers and we do that 22 also.
23 MEMBER SIEBER: Did you do the surveys?
24 MR. HENDRIXSON: Oh, yes.
25 MEMBER SIEBER: You do that periodically?
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52 1 MR. HENDRIXSON: Correct, six months or a 2 year. I forget the frequency.
3 MR. GRECHECK: And there's many other 4 inspections that we are not even describing here. I 5 mean we put people up in man baskets and inspected the 6 entire exterior of the containment ball, looking for 7 anything there. I mean we did a lot of visual 8 inspections throughout the plant looking for anything 9 that could be interpreted as damage.
10 MEMBER SIEBER: Did you test or inspect 11 penetration?
12 MR. HENDRIXSON: Yes.
13 MEMBER SIEBER: Pressure test them?
14 MR. HENDRIXSON: Yes, the Type C test.
15 MR. GRECHECK: Here's an example of one of 16 those earthquake indicators. This tank is one of the 17 susceptible tanks that came out of the list of the 18 IPEEE. This has this high confidence, low probability 19 failure HCLFPF value of only .19. So this would be 20 anticipated to be something that would be done of the 21 first things to show damage. And again, there was 22 nothing see here.
23 This is another low HCLFPF component 24 again. This is an as-found picture. You can see that 25 there is not even any disruption to the insulation.
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53 1 MEMBER CORRADINI: Just so I understand.
2 So when you did the green curve and you did that 3 analysis, did you tend to find large mass components 4 that would be the things that worried you or were 5 there small mass components like electrical relays or 6 cabinets or things that aren't as heavy, but if they 7 got wiggled at a different frequency, would really 8 cause a problem. Do you know what I mean?
9 MR. GRECHECK: Yes. We did corrective 10 actions to some of them, like for example, one of the 11 anticipated issues was that the suspended ceiling in 12 the control room which has one of those egg crates 13 diffuser panels, those could fall. So we fastened all 14 those together such that they would be less 15 susceptible to fall during an event.
16 There were cabinets that by tying the 17 cabinets together you were able to change their 18 frequency. There was a series of things that were 19 done in the post-IPEEE environment to try to fix those 20 things that could be.
21 MEMBER REMPE: When you started the diesel 22 generator, it had a leak and what was the cause of the 23 leak?
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54 1 installed.
2 MEMBER REMPE: Okay.
3 MR. GRECHECK: And that leak occurred into 4 its run. It was not right at start up.
5 MEMBER BROWN: Right.
6 MR. GRECHECK: All right, so summary, we 7 looked at 134 systems. We looked at 141 structures.
8 Forty-six of these susceptible components were 9 specifically looked at. Surveillance testing. We did 10 a comprehensive set of surveillance testing that 11 include MOV stroking, motor runs, just about anything 12 again. And again, not just looking for go, no go, but 13 looking for trending because we could look at the data 14 from the previous pre-earthquake test and say did we 15 see any change in behavior from pre-earthquake and 16 post-earthquake.
17 CHAIR ARMIJO: If you would go to your 18 fuel examination, Slide 18, the picture there. Was it 19 all visual or was there any kind of measurements, gaps 20 between the fuel assemblies?
21 MR. HENDRIXSON: It was a visual and an 22 enhanced visual and then with the close-up camera you 23 get those dimensions.
24 MEMBER CORRADINI: And you were looking 25 for some sort of bowing or --
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55 1 MR. HENDRIXSON: Yes, or deformation of 2 the ridge and things of that nature.
3 MEMBER BANERJEE: Did you go in with 4 endoscopic examinations, anything like that?
5 MR. HENDRIXSON: Most of it was face-on.
6 MEMBER BANERJEE: Face-on.
7 MR. GRECHECK: So a few short-term actions 8 that we completed before start up. One of the issues 9 we discovered is that our seismic instrumentation 10 dates essentially back to the early 1970s. It was not 11 designed for rapid analysis and it is not a free-field 12 instrument. It's based in buildings. The primary 13 data that we've been presenting to you here is from a 14 sensor that is in the basement of the Unit 1 15 containment right on the base map.
16 So some people have asked some questions 17 about was that truly free field and can you really 18 compare it? I think we were able to demonstrate that 19 it was close enough. But subsequent to the event, we 20 have installed a temporary free-field monitor on site, 21 away from any buildings. One of the nice things about 22 this is that you can see it's relatively small. It's 23 digital. It provides you the capability of 24 calculating CAV, for example, very quickly after an 25 event. And so in the future we'll be able to do the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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56 1 preliminary analysis much faster. And we've revised 2 our procedures specifically to tell the operators and 3 engineers how to use this equipment.
4 MEMBER SCHULTZ: Where did you locate it?
5 MR. GRECHECK: It's close to our training 6 center, so it's on the site, but it's in an open area 7 away from any buildings that could alter its response.
8 MEMBER SCHULTZ: Where there any other 9 findings related to the operational response, the 10 response of the operators, the response of the site 11 crew?
12 MR. GRECHECK: Actually, the site crew 13 performed in exemplary fashion. It was very, very, 14 very good response.
15 I think the staff will describe to you 16 some of the actions we agreed to and so I won't go 17 through these in detail. There's a Confirmatory 18 Action Letter which was issued to discuss some of 19 these long term --
20 MEMBER SIEBER: Before you jump to that, 21 part of the story of the event was that you started 22 four diesel, had to shut down one of them because of 23 a leak. What caused the leak?
24 MR. GRECHECK: Joy just asked that 25 question. The flange had been improperly installed.
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57 1 There was a gasket and a flange and that -- clearly --
2 MEMBER SIEBER: That event did not cause 3 the --
4 MR. GRECHECK: It was a prior maintenance 5 action that had caused the --
6 MEMBER SIEBER: You have an extra diesel, 7 right?
8 MR. GRECHECK: And we started that diesel 9 and that diesel functioned.
10 MEMBER SKILLMAN: Let me go back to 11 Steve's question The way your Operating and 12 Maintenance teams performed, was the trigger for their 13 actions you're having entered the unusual event and 14 then having followed your procedures from the ground 15 motion to giving instructions to your people? Was 16 that the flow or did the shift supervisor say oh, my 17 goodness, I've got a problem. I need everybody in 18 here right now with their flashlight.
19 MR. GRECHECK: Well, it occurred on day 20 shift on a Tuesday. So the shift manager, of course, 21 everybody felt the earthquake so he -- and we had a 22 dual-unit trip, so enter E0 appropriately. The AP 23 for seismic event and we actually went into an alert 24 so we -- the emergency response team then directed the 25 damage control team to actually recover a steam-driven NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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58 1 aux feed pump that was out of service in the middle of 2 a surveillance test. And then the shift manager, of 3 course, directed his crew to secure the diesel. It 4 was a coolant leak -- and load the SBODs all on to 5 that bus.
6 MEMBER SKILLMAN: I'm asking a larger 7 question. You were in a situation where you had a UE 8 and you were following your procedures for the UE and 9 it turned out what triggered the UE was an earthquake.
10 MR. HENDRIXSON: Actually, were in alert.
11 MEMBER SKILLMAN: Or an alert, I'm sorry.
12 MR. HENDRIXSON: And the alert was 13 actually called based on shift manager discretion 14 because he said I felt an earthquake. I've got do a 15 unit trip. Something serious is happening here and I 16 need to activate the emergency response organization.
17 MEMBER SKILLMAN: So you called your 18 people up.
19 MR. HENDRIXSON: Right. Thank you.
20 MEMBER SIEBER: I want to go back to the 21 diesel one more time. When you do maintenance on the 22 diesel when you're on the surveillance test crew, no 23 leak at that time, right? How long was that 24 surveillance test?
25 MR. HENDRIXSON: It was at least three NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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59 1 runs. Each is an hour long, plus --
2 MEMBER SIEBER: It's a start, load, and 3 run for an hour.
4 MR. HENDRIXSON: Exactly.
5 MEMBER SIEBER: You did not do anything 6 beyond that when you did the maintenance, right?
7 MR. HENDRIXSON: Those were the basic 8 post-maintenance tests.
9 MEMBER SIEBER: Didn't leak then.
10 MR. HENDRIXSON: Correct.
11 MEMBER SIEBER: Only leaked when the 12 seismic event, you concluded the seismic event didn't 13 cause it?
14 MR. HENDRIXSON: It actually didn't leak 15 for about 45 minutes. And then after that period of 16 time it began to leak.
17 MEMBER SIEBER: I guess operation is a 18 sort of a seismic event in and of itself as far as 19 it's concerned.
20 (Laughter.)
21 MEMBER SHACK: Gene, on North Anna 3, 22 there's a picture safe shutdown earthquake based on 23 our best modern knowledge and all our methods. It's 24 been reported that you even exceeded the safe shutdown 25 spectrum there, too. Is that right?
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60 1 MR. GRECHECK: At low frequencies, yes.
2 I pointed out before that the new models tended to 3 focus at higher frequency. The model that was in use 4 at the time of the early site permit which is not the 5 CEUS model that is now being released, but at the time 6 the early site permit which is in the 2003 time frame, 7 that model was -- did correctly predict an envelope, 8 the high-frequency vibrations, but it appears to have 9 under predicted the low frequency. So we are 10 examining that now and we are going to apply the CEUS 11 model to North Anna 3.
12 MEMBER BLEY: When you say "low 13 frequencies" what --
14 MR. GRECHECK: Two to three hertz.
15 MEMBER BANERJEE: The curve in the 16 spectrum that you've shown, you said I think that most 17 of the systems that you examined would not have been 18 damaged even by that green curve. What -- were there 19 some systems that would have been and which ones would 20 be?
21 MR. GRECHECK: So we get into this seismic 22 margin confidence type thing that HCLFPF value that I 23 was pointing out before. So analytically, we came up 24 with a list of about 50 items that you could not say 25 you had 100 percent confidence that they would survive NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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61 1 that event.
2 MEMBER BANERJEE: Typically, what were 3 these things, important things?
4 MR. GRECHECK: Yes. Many of them are 5 tanks. You have again high center of mass tanks. You 6 look at the way they're anchored to the ground. And 7 you say well, some of these might fail under those 8 kinds of accelerations. So I think it was mostly 9 tanks and --
10 MR. HENDRIXSON: Invertors were in there.
11 MEMBER STETKAR: Did you look at end beds 12 on your --
13 MR. HENDRIXSON: Yes.
14 MEMBER STETKAR: Are your switch gear up 15 high in the building?
16 MR. HENDRIXSON: We basically hand-over-17 handed the entire switchyard and actually in-depth 18 inspections of the switch gear. The energizer go in 19 and hand-over-hand --
20 MEMBER STETKAR: I don't know how they're 21 anchored.
22 MEMBER BANERJEE: Were these particularly 23 vulnerable to what part of that spectrum? Because if 24 you looked at it, the high frequency end was quite a 25 bit higher than the lower frequency. So was this NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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62 1 vulnerability coming from the low frequency part, the 2 high frequency part?
3 MR. GRECHECK: I think it was equipment 4 dependent. You would compare each piece of equipment 5 against its vulnerability, whether it's high or low.
6 MEMBER BANERJEE: And you could identify 7 this based on the frequency?
8 MR. GRECHECK: You can calculate what the 9 natural frequency of that particular item is, so 10 again, you would know where the harmonics would occur.
11 So things that are very massive, may have a lower 12 harmonic frequency than some of these smaller items.
13 So to wrap up again, acceleration criteria 14 were very briefly exceeded in certain directions, but 15 this was a very short direction earthquake. We had, 16 based on previous evaluations, we had established the 17 safe shutdown systems, could handle accelerations 18 above the design basis and I think this confirmed it.
19 No safety-related systems or structures or components 20 required any repair due to this event that we saw and 21 basically we did an extraordinarily comprehensive 22 review of the station and didn't find any damage.
23 And so on the basis of that and like I 24 said in a very extensive review by the staff and many, 25 many questions answered, we ended up receiving NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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63 1 permission to restart the units September 11th and in 2 the week or so subsequent to that, we restored both 3 units to 100 percent where they are today.
4 MEMBER SKILLMAN: I've got a question. I 5 see in your first slide was 21 million at inspection.
6 What was your lost generation for the time you were --
7 MR. GRECHECK: Actually, that's a very 8 difficult question to answer because by pure 9 happenstance, this was a very mild period. Late 10 August, early September, well, most of September in 11 Virginia was much cooler than it normally is. The 12 loads were down, so therefore it's kind of difficult 13 to specify what the financial, what the replacement 14 power cost was for that time period. Obviously, it 15 was substantial, but it was not as bad as it could 16 have been.
17 July was very hot and had it happened in 18 the months before, it would have been a much more 19 serious economic impact.
20 MEMBER SKILLMAN: Thank you.
21 MR. GRECHECK: Thanks.
22 CHAIR ARMIJO: Any other questions for the 23 speaker? In that case, we'll turn to the staff.
24 (Pause.)
25 MR. McCOY: Good morning. My name is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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64 1 Gerald McCoy and I am the Branch Chief for Region 2 2 for the Dominion plants. And I led the inspection 3 response to the earthquake in Mineral, Virginia.
4 When the earthquake occurred, the Senior 5 Resident Inspector, Greg Kolcum, was in the control 6 room at the North Anna Power Station and he was 7 observing the recently completed surveillance Mr.
8 Grecheck was talking about on the turbine-driven 9 auxiliary feedwater pump. We also had another NRC 10 inspector on site. His specialization was emergency 11 planning. He was on site during the earthquake and he 12 assisted in the response there on the site.
13 These inspectors observed the plant's 14 response during the event and immediately notified 15 Region 2. At the same time North Anna was declaring 16 an alert, 14 other nuclear licensees were declaring 17 NUEs due to the same earthquake. In response to these 18 notifications, the NRC activated its Operations Center 19 and the Regional Instant Response Centers to monitor 20 the affected plants.
21 North Anna was the only site to experience 22 reactor trip following the earthquake. The NRC 23 subsequently learned that the ground movement during 24 the earthquake exceeded the levels to which the plant 25 was originally designed at certain specific NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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65 1 frequencies.
2 Later, on August 23rd, Region 2 dispatched 3 an additional inspector to the site to assist in the 4 inspection effort. Also, a seismologist and a 5 mechanical engineer from here at White Flint were also 6 sent to the site within days of the event.
7 Because of the elevated risk from the loss 8 of offsite power from the failed diesel generator, an 9 evaluation was performed in accordance with Management 10 Directive 8.3 which is entitled "NRC Incident 11 Investigation Program." And it resulted in the 12 formation and dispatch of an augmented inspection team 13 to the site on August 29th. And their goal was to 14 better understand the circumstances of the event and 15 Dominion's response.
16 In addition to the augmented inspection, 17 a restart readiness inspection, and a start-up 18 monitoring inspection were also conducted to assess 19 the licensee's inspection process and to determine the 20 condition of the plant after the earthquake.
21 Mr. Mark Franke, DR's Branch Chief from 22 Region 2 led a team of seven inspectors, including a 23 seismologist, two structural engineers, two electrical 24 engineers, and two resident inspectors. The 25 inspection was conducted during the period of August NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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66 1 30th through October 3rd, 2011. The purpose of the 2 inspection was to conduct an independent review, 3 collect factual information and evidence of what 4 occurred at the plant as a result of the earthquake, 5 to assess the licensee's response and identify any 6 generic issues.
7 The team's primary focus was on the 8 plant's response to the event itself, rather than on 9 the evaluation of the plant to support eventual 10 restart. However, during the time period covered by 11 this inspection, Dominion was conducting tests and 12 inspections of plant structures and components.
13 Members of the augmented inspection team observed some 14 of these inspections and documented their observations 15 as part of the restart assessment process.
16 The results of the augmented inspection 17 team were provided at a public meeting held near the 18 North Anna Power Station on October 3, 2011. The 19 team's observations of the event included the 20 observation of the ground motion from the earthquake 21 exceeded the plant's license design basis at certain 22 frequencies.
23 At this point, no damage had been noted to 24 any safety-related systems of the plant. The safety 25 system functions were maintained during the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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67 1 earthquake. The operators responded to the event in 2 accordance with their established procedures and North 3 Anna responded to the event in a manner which 4 protected public health and safety.
5 MEMBER STETKAR: Gerry, your third bullet 6 there says some equipment issues. Is that limited to 7 the diesel or were there other items that you 8 identified?
9 MR. McCOY: There were other items. It's 10 the diesel itself. There was issues with the seismic 11 monitors. In particular, I'm thinking about there was 12 an issue caused by the power to the seismic monitors 13 and the alarms. That's why they had to declare the 14 alert on a call from the shift manager's advice from 15 the earthquake itself because they didn't get the 16 annunciator they were supposed to get, so we looked at 17 that, too.
18 There was one Juliet diesel was exhibiting 19 frequency oscillation, so the team noted that and we 20 looked into that further. The alph auxiliary 21 feedwater pump terry turbine lube oil level switch had 22 an issue that we wanted to look at and it turned out 23 just to be an alarm issue with an alarm that wasn't 24 expected, so we looked into it and it made sense in 25 the end.
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68 1 MEMBER STETKAR: There were other things, 2 but those are things that other than the power for the 3 seismic monitor, those are other things that could 4 occur during any what's called a plain vanilla trip.
5 MR. McCOY: Correct.
6 MEMBER STETKAR: Thanks.
7 MR. McCOY: The next inspection the NRC 8 conducted was what we called the restart readiness 9 inspection. This inspection was of Dominion's 10 readiness to restart the North Anna units and have 11 occurred from October 5th to November 7th, 2011. The 12 objectives of this inspection was independent evaluate 13 Dominion's assessment that no functional damage had 14 occurred to safety systems which included evaluation 15 of the licensee's walkdown, their corrective action 16 follow up and the review of their actions to support 17 start up.
18 This team was led by Mr. Andy Sabisch.
19 Mr. Sabisch is the NRC Senior Resident Inspector at 20 the Oconee Nuclear Power Station. He led a team of 21 eight inspectors including participation from other 22 NRC regional and headquarters offices with experience 23 in structures, piping, electrical components and plant 24 operations.
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69 1 assessment of Dominion's inspections and testing of 2 systems and components. A risk-informed sample of the 3 plant systems or walkdown by NRC inspectors and these 4 observations were compared with those made by 5 Dominion. The team reviewed the evaluation so what 6 was found during Dominion's walkdowns to determine if 7 the issues were properly categorized. The team also 8 reviewed the licensee's plan for starting up the 9 plant. The results of this inspection provided an 10 input into the eventual NRC approval to restart the 11 plants.
12 The conclusions reached by this inspection 13 team was that the licensee's inspection process was 14 adequate to identify any damage which had occurred to 15 the safety significant systems in the plant. The team 16 members performed a limited number of inspections of 17 risk-significant systems in areas and no significant 18 damage was identified. The team conducted spot checks 19 to verify that the licensee properly evaluated any 20 damage which was identified during the license's 21 inspection. The team did not identify any damage to 22 safety-related equipment from the seismic event.
23 Minor issues identified by the restart readiness team 24 such as the identification and non-earthquake related 25 damage which had not been entered into the licensee's NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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70 1 corrective action process and enhancements which could 2 be made to the two hotel emergency diesel generator 3 root cause evaluation.
4 MEMBER SCHULTZ: Excuse me, what are the 5 examples you might give for the items that were not in 6 the Corrective Action Program?
7 MR. McCOY: Not in the Corrective Action 8 Program. There were cases that the inspectors, I 9 mean, you send inspectors out in the plant and they're 10 going to find things. That's what we encourage them 11 to do. The things they found were like they found 12 corkboard in odd places. They found damage to 13 insulation. It wasn't related to the earthquake 14 itself. It wasn't the case where two pipes were 15 hitting, but it's just damaged stuff and they talk to 16 the guy who is beside him and said hey, is this in the 17 corrective action system? And they said no, and they 18 said why not? Isn't that the process?
19 So it was just a case of me sending 20 inspectors out and finding issues and making sure 21 licensees got it on their list of things to correct.
22 But it wasn't related to the earthquake, so we just 23 put it in their process and carried on with our 24 inspection.
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71 1 wasn't there? Did they answer that?
2 MR. McCOY: The licensee -- there was 3 concern. There was a concern in the discussion 4 between myself and the licensee and it was -- it's not 5 something we usually see with Dominion, so I was kind 6 of concerned that the fact that all of a sudden now 7 you guys aren't putting things in your corrective 8 action process, what's the problem? And they did stop 9 and have a rebrief for their employees and say we are 10 having issues. We are here specifically to look at 11 the earthquake damage, but we still have to follow 12 regular processes. So I think -- I attributed it to 13 the loss of focus on their part. They were focusing 14 on the earthquake. They didn't quite see the other 15 things our inspectors coming in with new eyes were 16 seeing about their plant.
17 Next is a start-up monitoring inspection.
18 NRC continued the inspection process while the 19 licensee was in the process of restarting the plant.
20 The inspection was conducted during the start up of 21 both Unit 1 and Unit 2 from November 11th through 22 November 29th, 2011. The objective of this inspection 23 was to independently evaluate Dominion's assessment 24 that no functional damage had occurred to safety 25 systems through the observation of control room NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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72 1 activities, surveillance tests, and inspections of 2 important plant systems as conditions change during 3 start up.
4 This inspection was led by Mr. Rodney 5 Clagg. Mr. Clagg is the NRC's resident inspector at 6 North Anna Power Station. He led a team of seven 7 resident inspectors from other nuclear power plants.
8 This team concluded that the licensee's process 9 ensured that the structure systems and components of 10 the North Anna Power Station could perform their 11 safety functions following the earthquake and would 12 support a return to the safe power operation without 13 undue risk of health and safety to the public.
14 This inspection team completed this 15 verification through the observation of control room 16 activities and direct inspection of start-up 17 activities including mode changes, heat up, reactor 18 start up, power extension for cold shutdown to rated 19 thermal power. It also included direct inspection of 20 surveillance testing, operability determinations, 21 maintenance risk assessments, emergent work control, 22 modifications, post-maintenance testing, and a review 23 of Corrective Action Program documents, partial 24 inspection walkdowns of selected systems, structures, 25 and components including secondary systems and other NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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73 1 activities as applicable. No additional earthquake-2 related damage was identified to the plant systems 3 during the start-up process.
4 I now invite Ms. Meena Khanna, the Branch 5 Chief for the NRC's Office of Nuclear Reactor 6 Regulation to discuss the Agency's technical review 7 efforts.
8 MS. KHANNA: Thank you, Gerry. Again, my 9 name is Meena Khanna and I did lead the technical 10 review efforts out of NRR.
11 There was a question earlier that I just 12 wanted to touch base on. There was a question about 13 the IPEEE curve. And we found the guidance document.
14 It's NUREG-1407. So I just wanted to mention that to 15 you. So hopefully that will address it. And if you 16 need any additional information, we can ask our 17 seismic expert, Dr. Nilesh Chokshi, to help us out 18 with that as well. Okay?
19 The restart requirements. The regulatory 20 requirements governing this event are delineated in 10 21 CFR Part 100 Appendix A. Basically this states that 22 if the vibratory ground motion exceeds that of the 23 operating basis earthquake, then the shutdown of the 24 nuclear power plant will be required.
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74 1 operations, the licensee will need to demonstrate to 2 the Commission that no functional damage has occurred 3 to those features necessary for the continued 4 operation without the undue risk to the health and 5 safety of the public.
6 I'd like to take a second here to also 7 indicate that I will be interchangeably using the 8 terminology of safe shutdown earthquake and design 9 basis earthquake. They mean the same for North Anna.
10 So if you near me say SSE, safe shutdown earthquake.
11 That is the same as design basis earthquake.
12 As far as the technical review, the 13 regulatory review guidance that the NRC followed was 14 established in the mid-1990s. As you heard Mr.
15 Grecheck address the Reg. Guide 1167 which is entitled 16 "Restart of a Nuclear Power Plant Shut Down by a 17 Seismic Event" which is endorsed by the EPRI NP6695 --
18 I'm sorry, which endorses the EPRI NP6695 guideline 19 was also used. And that's entitled "Guidelines for 20 Nuclear Plant Response to an Earthquake."
21 I'd also like to note that the EPRI 22 guidelines does talk about guidance on what to do if 23 the plant exceeds the OBE as well as design basis 24 earthquake. Both short-term and long-term actions are 25 addressed in the EPRI guidelines. In addition to the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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75 1 EPRI guidelines and the Reg. Guide, we also took it 2 one step further and used the IAEA Safety Report No.
3 66 which also addresses lessons learned from the 4 International Plant which was the Kashiwazaki plant in 5 Japan and this plant had also exceeded its design 6 basis earthquake. So this provided valuable 7 information to us in conducting our reviews, 8 especially with respect to hidden defects.
9 MEMBER CORRADINI: So if I might just ask, 10 so in the conversation with Gene, there was -- I don't 11 want to call it an inconsistency, a difference between 12 10 CFR 100 and the Reg. Guide which points to the EPRI 13 document in terms of -- maybe I'm misinterpreting, so 14 I'm not sure if it's inconsistent or it's just a 15 different term. Are you going to address that here?
16 MS. KHANNA: Yes, just the 10 CFR Part 100 17 basically just indicates that if you do exceed the 18 OBE, then the plant will be required to be shut down 19 and NRC approval needs to be addressed, needs to be 20 sought from the licensee. However, the EPRI 21 guidelines goes into what the plant needs to do to 22 address what actions need to be taken once it's 23 exceeded the OBE in licensing. Is that what you were 24 getting at?
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76 1 do this wrong, so let me try again. So the way you 2 just explained it is we looked at this multi-colored 3 set of curves and then given the fact that they 4 exceeded what they were designed for, that puts them 5 in a situation they have to look at things. But then 6 they look at the Reg. Guide to decide what they have 7 to do in terms of -- Gene had a decision matrix.
8 MS. KHANNA: That's right and that comes 9 out of the EPRI guideline so the Reg. Guide endorsed 10 the EPRI guidelines.
11 MEMBER CORRADINI: Let me posit one thing.
12 So in the north-south -- I don't remember what 13 direction it was, the blue bar was slightly above the 14 black line. That black line comes out of the Reg.
15 Guide. Am I correct in understanding that? And that 16 points to the EPRI document. So you -- based on some 17 natural event, you exceed what is their design base, 18 but then once you go in terms of this only if that 19 blue bar gets above the black line do -- any more than 20 a zero corridor inspection.
21 Am I interpreting that correctly? I want 22 to make sure I get this right.
23 MS. KHANNA: I think you've got it 24 correct. The EPRI guidelines will indicate to you 25 that the level, based on the amount of damage the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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77 1 plant sees at the site, that basically tells them what 2 level they need to go and when we're talking about the 3 various levels that going to be in the EPRI 4 guidelines. Does that help? Okay.
5 Okay, so in addition to the IAEA safety 6 report, obviously we have great technical expertise 7 here, so we also utilized the technical expertise that 8 we had and that was really helpful with the area of 9 fuels and on the evaluation as well, which I'll get 10 into a little bit more detail later.
11 Like I indicated, significant level of NRC 12 effort was placed to independently evaluate the impact 13 of the seismic event including structural and seismic 14 experts throughout the Agency. We also dedicated a 15 special restart team. We had several senior level 16 advisors as part of this team dedicated project 17 managers, so we took this very seriously and had a 18 separate team that was working basically on this 24 --
19 I'm not going to say 24/7, but around the clock and 20 doing what we needed to do.
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78 1 mentioned earlier. And again, the staff did not 2 identify any significant safety issues stemming from 3 the seismic event.
4 As Allen had indicated earlier, the NRC's 5 inspection assessment activities did involve a wide 6 spectrum of technical disciplines and there was 7 definitely coordination among the reviews and the 8 inspection activities across the offices with the 9 Agency.
10 Also, as part of this, I'd like to mention 11 that we did come up with an action plan. We developed 12 an action plan. There were so many activities going 13 on. As you heard, the inspection activities -- there 14 were audits done on the fuels that I'll talk about 15 later. We have 2.206 petitions. As you can imagine 16 there were quite a few public meetings, Commission 17 briefings. And also what we wanted to do was make 18 sure that we captured the short-term actions as well 19 as the long-term actions and Gerry had mentioned that 20 there were -- I don't know if he had mentioned it, but 21 there were two generic issues that were identified out 22 of the AIT inspection report and those were both with 23 respect to the seismic monitoring instrumentation. So 24 what we've got in place right now is we're putting 25 together an information notice to address those two NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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79 1 generic issues. So again, all these items are being 2 tracked within our action plan. We also developed a 3 com. plan because we believe that was important.
4 The NRC performed a comprehensive 5 independent technical review to ascertain whether it 6 was acceptable for the North Anna plant to restart.
7 This slide lists many of the technical areas that were 8 reviewed which includes reactor vessel internals as 9 well as mechanical structural engineering and 10 electrical engineering. I won't go through all of 11 this, but based on this list, you can see that almost 12 every single technical branch in NRR was impacted and 13 was involved in this review.
14 I'd like to highlight a few examples to 15 demonstrate the independent nature of our review. To 16 address the integrity of the fuels, we did conduct 17 audits of the fuel and I believe Tony Mendiola, his 18 group actually went to the site and reviewed 19 Dominion's efforts for confirming the integrity of the 20 fuel. In response to our review of Dominion's 21 efforts, Dominion also performed additional 22 calculations to demonstrate the integrity of the fuel 23 assembly components to ensure that they were not 24 compromised as a result of the earthquake.
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80 1 systems, Dominion performed additional analyses as 2 well as to provide the NRC staff confidence that the 3 earthquake did not adversely impact the piping and to 4 ensure that the previous analyses were not invalidated 5 as a result of the earthquake. For example, a leak 6 before a break, and just ensuring that any prior 7 existing flaws were not impacted by the earthquake as 8 well.
9 Also, I'd like to mention that with 10 respect to inspections of snubbers, Dominion had 11 committed to doing functional testing of the snubbers 12 with respect to Unit 2 and as a result of our 13 questioning attitude, they also completed functional 14 testing of the snubbers for Unit 1 as well.
15 And then later on in the presentation I'll 16 talk about the long-term activities, long-term items 17 that were addressed in the CAL and that was also due 18 to the questioning attitude of the staff license 19 renewal, was heavily involved in that because as you 20 know, there was a license renewal issue for this 21 plant. So there were several activities that came out 22 of that that will be addressed in that Confirmatory 23 Action Letter.
24 NRC staff conducted a safety review in 25 accordance with the established acceptance criteria.
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81 1 This was a first of a kind review. The staff -- this 2 was very basically new to the staff. It was a complex 3 review, so we wanted to ensure that we had consistent 4 technical reviews across the office. So before we 5 started a review, we came and developed some 6 acceptance criteria and really what helped us 7 Inspection Manual Chapter 9900. That gave us good 8 guidance and that's basically the operability 9 determinations and functionality assessments for 10 resolution of degraded or nonconforming conditions.
11 So that was the basis of our acceptance review 12 criteria. And that really helped out. We made sure 13 that we had Office of General Counsel involved and 14 made sure that in every step that we were doing that 15 they were watching what we were doing and making sure 16 that we weren't doing anything illegal.
17 The NRC ensured that Dominion demonstrated 18 that the plant is safe to operate prior to approving 19 restart. And as we indicated earlier, the staff did 20 not identify anything from our inspections or the 21 technical review to preclude plant operations as a 22 result of the seismic event. The results that were 23 reviewed determined that the plants may be restarted 24 safely and the bottom line was that the NRC was not 25 going to allow plant restart until we were confident NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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82 1 that it would be operated safely.
2 And as Mr. Grecheck indicated, on November 3 11, 2011, after the plant was shut down for 4 approximately 80 days, the Office Director of the 5 Office of Nuclear Reactor Regulation issued the 6 restart approval decision for both North Anna Units 1 7 and 2. The decision was based on the staff's 8 independent assessment which concluded that Dominion 9 had acceptably demonstrated that no functional damage 10 occurred to those features necessary for continued 11 operation as a result of the August 23rd earthquake, 12 thereby ensuring that there was no undue risk to the 13 health and safety of the public.
14 I'm sure you've read our safety 15 assessment. You can find that it's extremely 16 comprehensive. We tried to make sure that we captured 17 everything. Again, this was a one time -- this was a 18 first of a kind event and we wanted to make sure we 19 captured our technical review in case we needed it for 20 knowledge transfer later on in the future. Also, we 21 issued a confirmatory action letter to address the 22 licensee's commitments for long-term actions.
23 The next few slides, I'm not going to go 24 through each of the ten long-term actions that were 25 identified in the CAL. However, I do want to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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83 1 highlight a few items here. Dominion did commit to 2 perform the long-term evaluations in accordance with 3 the NRC endorsed guidance, so the EPRI guidelines do 4 talk about long-term actions and that's what Dominion 5 committed to. We completed our reviews regarding 6 these evaluations and the long-term commitments are 7 addressed in the NRC CAL which is also dated November 8 11, 2011.
9 As indicated earlier, as a result of the 10 earthquake, the plant exceeded its design basis 11 earthquake ground motion. To address this issue, 12 Dominion committed to update their final safety 13 analysis report to include this new seismic ground 14 motion as reflected in the August 23rd earthquake 15 which is also addressed in Item 3 of the Confirmatory 16 Action Letter and that's identified as multiple due 17 dates.
18 With regards to Item 10 --
19 MEMBER RAY: Could you back up? Item 2 up 20 there isn't very far off, March 31, 2012. And is 21 there any insight at all on the source 22 characterization? Does the NRC have any work in 23 progress to look at that or are you waiting for a 24 submittal?
25 MS. KHANNA: Kamal?
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84 1 MR. MANOLY: This is Kamal Manoly with 2 NRC. That started to be addressed as part of the 3 50.54f letter that will be issued some time which 4 essentially is an extension of GI-199.
5 MEMBER RAY: Okay, so basically, it's not 6 going to be something special for this event.
7 MR. MANOLY: That's correct.
8 MEMBER RAY: Given all else that's going 9 on in that area.
10 MR. MANOLY: Dominion committed that they 11 would follow whatever action comes out of the GI-199 12 effort.
13 MEMBER RAY: Okay, it's just an 14 interesting action item to have in a Confirmatory 15 Action Letter.
16 MS. KHANNA: You bring up a good point as 17 well. There was close coordination with the Near-Term 18 Task Force on the Fukushima and actually the seismic 19 monitoring instrumentation, that was one issue that 20 they were going to be addressing as part of the 21 lessons learned, but they thought it would be more 22 appropriate for us to address it, so that's why we're 23 pursuing the information notice.
24 As Kamal indicated the GI-199 efforts, all 25 of that we're making sure that everything is tied --
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85 1 MEMBER RAY: It's just the date seems 2 awfully close. That's why I asked.
3 MS. KHANNA: I just wanted to highlight, 4 so item ten, the long-term commitment entails that 5 Dominion will use the recent ground motion spectrum 6 from the August 23rd earthquake in conjunction with 7 the original design basis earthquake seismic 8 qualification of new and replacement equipment. So 9 this was one item that we -- the staff was requesting 10 of the licensee and wanted to make sure that for new 11 and replacement equipment that they were considering 12 the response spectra from the existing design basis 13 earthquake as well as from the as-felt earthquake that 14 was seen from the August 23rd earthquake.
15 Again, the long-term commitments were 16 consistent with those identified in the EPRI 17 guidelines. However, you'll note that in the list 18 there are a few that stem from the license renewal 19 folks because there is a license renewal application 20 that was approved. So there are a few license renewal 21 commitments included. For example, MRP-227. And 22 again, as I mentioned the staff did issue an action 23 plan and that's where we're going to be tracking the 24 closure of all these CAL action items.
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86 1 open it up for questions.
2 CHAIR ARMIJO: Item 7, you want them to 3 do comparative calculated loads from the earthquake 4 and the existing leak before break analysis. What 5 drove that request in view of the condition of the 6 plant?
7 MS. KHANNA: I'll give a high level -- I 8 don't know if we have the appropriate person, but I 9 believe what they want to do is any analyses that had 10 been done for license renewal, they wanted to make 11 sure that they were still valid. So I think they 12 wanted to make sure that if there were any different 13 stresses, but -- do you guys want to help me out, 14 please?
15 CHAIR ARMIJO: Is anybody else -- well, 16 I'm just wondering.
17 MR. TSAO: This is John Tsao from Division 18 of Engineering. The reason we ask licensee to do 19 recalculation of leak before break analysis is that 20 leak before break is to satisfy GDC-4 and GDC-4 21 requires a Commission-approved leak before break 22 analysis. Because of the seismic event we think that 23 the loads, the seismic loads may increase and we are 24 wondering whether the current leak before break 25 analysis approved for North Anna still satisfies the NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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87 1 staff's recommended safety margin in the Standard 2 Review Plan 363. So this is a confirmatory analysis 3 to make sure that leak before break application is 4 still valid for North Anna.
5 CHAIR ARMIJO: Okay. It just seems like 6 the condition of the plant and leak before break --
7 MEMBER SHACK: Remember, with leak before 8 break you have to postulate a big flaw that doesn't 9 really exist, so they're looking for that margin. So 10 with the higher loads and the postulated big flaws, it 11 has to demonstrate a margin. Even though it looks 12 fine, you still need the analysis.
13 MEMBER RAY: Higher loads resulting from 14 this event or --
15 MEMBER SHACK: Just the seismic loading 16 now seems to be somewhat higher than originally -- the 17 spectrum has been exceeded.
18 MEMBER RAY: By this event.
19 MEMBER SHACK: By this event.
20 MEMBER RAY: You're talking about this 21 event though.
22 MEMBER SHACK: Right.
23 MEMBER RAY: Not some other change in the 24 design basis.
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88 1 event, right.
2 CHAIR ARMIJO: Okay, thank you.
3 MEMBER SHACK: That they advise, too, 4 Harold.
5 MEMBER RAY: I understand. But I'm trying 6 to keep them separate in my mind anyway.
7 MEMBER STETKAR: Meena, as part of the 8 lessons learned from this, do you anticipate any 9 revisions to Reg. Guide 166 and 167?
10 MS. KHANNA: That's a good question. Yes.
11 Research, right now is going through a revision of 12 Reg. Guide 1.667 and we're actually providing a lot of 13 feedback to that. The Reg. Guide does need to be 14 updated. It's been a while since it's been updated, 15 so there are a lot of lessons learned that we gain 16 from this review. Probably more robust than the Reg.
17 Guide. I think you'll see a lot of the RAIs that we 18 asked -- the staff is doing a great job.
19 MEMBER STETKAR: Anything on 1.166 as far 20 as planning and operations?
21 MS. KHANNA: To be honest with you, I'm 22 not aware of any. We haven't seen an update.
23 MEMBER STETKAR: Thank you.
24 MR. WIDMAYER: Meena, the Reg. Guides are 25 -- the Reg. Guides promote the EPRI document. Is NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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89 1 there's something going on where they're being 2 reevaluated and updated?
3 MS. KHANNA: I'm not sure about that, but 4 what we will do is when we put the Reg. Guide out, if 5 we do any updates, obviously that would precede what's 6 in the EPRI guidelines. So I haven't heard of any 7 updates of the EPRI guidelines, but I would think that 8 once we -- I don't know, David, if you would know, but 9 --
10 MR. MANOLY: In the Reg. Guides that 11 endorses the EPRI 6.695, it endorses conditions and my 12 expectation is if EPRI does not revise the document, 13 we will add more conditions in the Reg. Guide.
14 MEMBER BLEY: There was a discussion 15 earlier when the licensee was here about the 16 regulation requiring that you meet the design spectra 17 or that the spectra is met and the Reg. Guide making 18 a definition based on CAV that if you're within that 19 value of CAV you don't exceed the OBE.
20 Is that an actual conflict? How is that 21 to be resolved and is this leading to any thoughts 22 about how the design basis will be formulated or 23 defined in the future for new reactors?
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90 1 the design of the structures and components and the 2 Reg. Guide talks about exceedance when you have an 3 earthquake that's felt. So what is the design tool?
4 I think we tried to articulate that point. The CAV is 5 a measure to determine the threshold beyond which you 6 should consider that you exceed the OBE.
7 MEMBER BLEY: So that is the basis for 8 staff looking at an actual earthquake and deciding if 9 you exceed the OBE.
10 MR. MANOLY: Yes, that's the Reg. Guide.
11 That's in the record. But the design for the plant is 12 the design spectra, the ASME, that's for the actual 13 design structure and components with the margins that 14 exist in the design process.
15 MEMBER BLEY: How is the requirement for 16 how long -- if the component is tested on a shake 17 table for the duration of the shaking arrived at and 18 is that something that NRC approves or is that 19 something that the licensee decides?
20 MR. MANOLY: Typically, the equipment are 21 tested by -- qualified by testing, some are qualified 22 by analysis. When you qualify equipment by testing, 23 you do it to one SSC and five OBEs.
24 MEMBER BLEY: And for what duration.
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91 1 around 30 seconds typically.
2 MEMBER BLEY: It's not a requirement?
3 MR. MANOLY: I believe it's in the IEEE 4 44, but I believe the duration is around 30 seconds.
5 MEMBER BLEY: It's not something you 6 regulate other than may be referring to the IEEE?
7 MR. MANOLY: In Reg. Guide 100 Rev. 3, it 8 endorses the EPRI 344 for electrical equipment and now 9 it endorses the ASME fuel made for qualification of 10 the technical equipment.
11 MEMBER BLEY: It's a little more complex 12 than I can completely understand here on the fly.
13 MEMBER CORRADINI: But just to follow up 14 Dennis' question, given the fact you're going to have 15 lessons learned from his from how you connect the Reg.
16 Guides to the requirements, I think at least some of 17 us like to understand how all this is going to --
18 MEMBER BLEY: That's kind of where I was 19 coming from.
20 MEMBER CORRADINI: Is that a fair way to 21 putting it?
22 MS. KHANNA: Yes.
23 MEMBER POWERS: Are there any other 24 questions?
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92 1 you pointed us to a NUREG for understanding the IPEEE 2 spectrum, actually that Reg. Guide tells how the 3 IPEEEs were done and says you can either do a seismic 4 PRA which would develop a site specific hazard curve, 5 or you can do an EPRI margin study or an NRC margin 6 study. The NRC margin study refers you to another 7 NUREG CR that develops kind of a generic spectrum for 8 mild or moderate rock or soil site. I suspect it's 9 over there, but that's not on the website.
10 MEMBER SKILLMAN: Mr. Chairman, I would 11 like to make a comment. I'd like to compliment the 12 staff and the Dominion team for really taking to heart 13 an abundance of caution when it might have been 14 another utility that would have arm wrestled, would 15 have said we're so close to the CAV we really don't 16 have to do anything. Independent of how much money 17 was spent, this exercise has shown in this particular 18 case how robust this machine is. But it has also 19 demonstrated a nuclear safety attitude that at least 20 I for one am very pleased to be around. So I want to 21 say thank you.
22 MEMBER SIEBER: Well, I think that 23 compliment should extend to the licensee also.
24 MEMBER SKILLMAN: Oh, yes. That's what I 25 was trying to say to the Dominion team. Thank you.
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93 1 MEMBER POWERS: Sure.
2 CHAIR ARMIJO: All right. Thank you, 3 Dana. Thank the staff. We're now going to take a 4 break and we'll reconvene at 10:30.
5 (Whereupon, the above-entitle matter went 6 off the record at 10:17 a.m.)
7 8
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ACRS Full Committee Briefing January 20, 2012 North Anna Power Station Earthquake Assessment
North Anna Inspection Summary Process
- More than 100,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />
- $21 million in inspection, testing, & evaluation
- Exceeded NRC endorsed guidance Findings
- No functional damage to safety systems 2
Forecasting Seismic Damage Key factors
- Acceleration (vertical, north/south, east/west)
- Frequency of the vibration
- Duration of strong motion Seismic acceleration response spectra
- Used to conservatively design plants
- Does not account for duration Cumulative Absolute Velocity (CAV)
- Integrates all three factors
- Best indicator of energy imparted
- Best indicator of damage 3
Response Spectra Comparisons 4
August 23rd Earthquake:
A strong, but very short event East-West: 3.1 sec Vertical: 1.5 sec North-South: 1.0 sec 2 4 6 8 10 12 14 16 18 20 seconds 5
Slightly Exceeded in One Dimension Regulatory Limit August 23, 2011 Earthquake DBE - Design Basis Event IPEEE Review - 1990s updated study 6
North Anna Has Significant Design Margin
- Conservatism in analytical methods
- Conservatism in American Society of Mechanical Engineers Code
- Accident load design of greater capacity
- Conservatism in seismic test standards Previous Evaluations Established Significant Margins Beyond Design Basis 7
The Plant Told the Story Unit 2 Turbine Building Non-Safety Related Demineralizer Tanks Base Pedestal 9
Unit 1 Containment Surface Crack In Interior Containment Wall 10
Dry Cask Storage Casks moved between 1 and 41/2 inches 11
Dominion Complied with and Went Beyond Regulatory Guidance
Regulatory Guidance Station restart readiness assessment actions based on NRC-endorsed guidance RG 1.166, Pre-earthquake Planning and Immediate Nuclear Power Plant Operator Post-earthquake Actions, March 1997 RG 1.167, Restart of a Nuclear Power Plant Shut Down by a Seismic Event, March 1997 EPRI NP-6695, Guidelines for Nuclear Plant Response to an Earthquake, December 1989 13
EPRI NP-6695 Figure 3-1 Short-Term Actions 14
EPRI NP-6695 Figure 3.2 Flow Diagram of Post-Shutdown Inspections and Tests EPRI Damage Intensity of 0 15
Demonstration Plan
- Conservatively Inspected Beyond EPRI Damage Intensity 0 Classification
- Assessments & Evaluations for NRC
- Requests for Additional Information (~ 130)
- Onsite Inspections
- Augmented Inspection Team
- Restart Readiness Inspection Team
- Root Cause Evaluation of Reactor Trip 16
Investigated Components Most Likely to be Damaged Unit 2 Tunnel Inspection 17
Extensive Fuel Inspections Visual inspection of RCCA hubs Examination of underside of a mid-span mixing grid 18
Buried Piping
~ 100 ft of safety-related buried pipe visually inspected with wall thickness verified by Ultrasonic Testing 19
Chemical Addition Tank HCLPF value
= 0.19 No seismic damage identified 20
Boric Acid Storage Tank HCLPF value
= 0.21 No seismic damage identified 21
Inspection Results 134 System inspections completed 141 Structure inspections completed 46 Low HCLPF inspections completed
~ 445 Surveillance Tests/unit through Mode 5
~ 29 tests/unit after exceeding Mode 4 nspections Confirmed EPRI Damage Intensity of 0 22
Subsequent Actions Short-Term Actions Installed Key Seismic Monitoring Equipment Revised Procedure to Respond to Earthquake 24
Long-Term Actions
- Install permanent free-field seismic monitoring instrumentation
- Re-evaluate safe shutdown equipment (components with identified lower margins)
- Perform seismic analysis of recorded event consistent with EPRI guidance
- Maintain seismic margins in future modifications
- Revise the North Anna Safety Analysis Report 25
Summary
- Acceleration criteria were briefly exceeded in certain directions and frequencies by a strong, but very short duration earthquake
- Previous evaluations establish safe shutdown systems, structures and components can handle peak accelerations above design basis
- No safety-related systems, structures or components required repair due to the earthquake
- No significant damage was found or should have been expected and results of expanded tests and inspections have confirmed expectations 26
Acronyms CAV - Cumulative Absolute Velocity CR - Condition Report DBE - Design Base Earthquake EPRI - Electric Power Research Institute FSRC - Facility Safety Review Committee HCLPF - High Confidence of Low Probability of Failure IPEEE - Individual Plant Examination of External Events MCR - Main Control Room PT - Penetrant Test S/G - Steam Generator SSC - Systems, Structures and Components RCCA - Rod Cluster Control Assembly RG - Regulatory Guide UPS - Uninterruptible Power Supply UT - Ultrasonic Test VT - Visual Test 27
Advisory Committee on Reactor Safeguards 590th Full Committee Meeting January 20, 2012 Gerald McCoy, Region 2 Meena Khanna, NRR/DORL
NRC Inspection Effort Initial Response Augmented Inspection Team Restart Readiness Inspection Startup Monitoring Inspection 2
Augmented Inspection Team Purpose Conduct an independent review Collect factual information Assess the licensees response Identify any generic issues 3
Augmented Inspection Team Results No significant damage Safety system functions maintained Some equipment issues North Anna responded to the event in a manner which protected public health and safety 4
Restart Readiness Inspection Purpose Evaluation of Licensees walkdowns Corrective action follow-up Review of actions in support of startup 5
Restart Readiness Inspection Results The licensee adequately inspected plant SSCs to ensure that any damage would be identified No seismically-induced damage was identified which could affect the operability or functionality of plant SSCs Minor issues were identified 6
Startup Monitoring Inspection Purpose - SSCs could perform their functions through observation of control room activities, surveillances, and system walkdowns.
Results - The licensees processes adequately ensured that the SSCs had not been degraded following the earthquake 7
Technical Review Efforts 8
Restart Requirements Appendix A to 10 CFR Part 100 Appendix A to Part 100Paragraph V(a)(2) states, If vibratory ground motion exceeding that of the Operating Basis Earthquake occurs, shutdown of the nuclear power plant will be required.
Prior to resuming operations, the licensee will be required to demonstrate to the Commission that no functional damage occurred to those features necessary for continued operation without undue risk to the health and safety of the public.
9
Technical Review Regulatory Guidance Actions prior to restart Long Term Actions 10
Key Technical Areas of Review
- Reactor Vessel Internals Fuels
- Reactor Systems Pumps and Valves
- Mechanical/Structural Eng. Balance of Plant
- Instrumentation & Controls Containment
- Electrical Engineering Steam Generators
- Piping Fire Protection 11
Technical Review Summary The NRC safety reviews were completed as part of the restart decision making process.
The NRC ensured that Dominion demonstrated that the plant was safe to operate before approving restart.
Inspections Completed During Restart 12
NRR Startup Decision Eric Leeds, Director of NRR NAPS received restart approval on November 11, 2011 after shutdown of 80 days
NRR Confirmatory Action Letter 10 LongTerm Actions
- 1) Evaluate plant SSCs in accordance with RG1.167/EPRI NP6695 Due April 30, 2013
- 2) Plan to characterize the seismic source and any special ground motion effects Due March 31,2012
- 3) Revise the North Anna Updated Final Safety Analysis Report to document the event, evaluations and incorporation of RG 1.167/ EPRI NP6695 Multiple Due Dates
- 4) Implement upgrades to existing seismic equipment and MCR indication and install permanent, seismically qualified backup power to a new Seismic Monitoring Panel Due December 31, 2012
NRR Confirmatory Action Letter, Contd
- 5) Reevaluate the plant equipment identified in the IPEEE [Individual Plant Examination of External Events] review with HCLPF [high confidence of low probability of failure] capacity <0.3g Due March 31, 2013
- 6) Plan with the NSSS vendor to assure long term reliability of the reactor internals.
Due February 29, 2012
- 7) Compare calculated load from the earthquake and the existing LBB analysis Due March 31, 2013
- 8) Perform inspections at North Anna Power Station in accordance with the latest MRP227 revision March 31, 2013
NRR Confirmatory Action Letter, Contd
- 9) Reevaluate the TimeLimiting Aging Analyses that include seismic inputs to either: 1) quantitatively demonstrate that the TLAAs are still bounding, or 2) reanalyze the TLAAs, based on the August 23, 2011 earthquake.
Due March 31, 2013
- 10) Implement long term Seismic Margin Management Plan to address the impact of the August 23, 2011 earthquake to ensure adequate seismic margins are maintained for plant using InStructure Response Spectra (ISRS) for buildings containing safety related SSCs Due December 31, 2011
For Additional Information:
http://www.nrc.gov/aboutnrc/emerg preparedness/virginiaquakeinfo.html 17
Question/Answer Session 18