ML20217Q711
| ML20217Q711 | |
| Person / Time | |
|---|---|
| Issue date: | 03/31/1998 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| ACRS-T-3031, NUDOCS 9804130117 | |
| Download: ML20217Q711 (333) | |
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{')f OFFICIAL-TRANSCRIPT OF PROCEEDINGS NUCLEAR REGULATORY COMMISSION i
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. ADVISORY COhlhilTTEE ON REACTOR SAFEGUARDS c
Title:
ADVANCED REACTOR DESIGNS !
SUBCOhlhflTTEE l
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THANKS' i 1 Docket No.:
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' Work Order No.: . ASB-300-221 t
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LOCATION: Rockville, Maryland 4 i DATE: Tuesday, March 31,1998 L/
PAGES: 1 - 308 ,
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i 1 UNITED STATES NUCLEAR REGULATORY COMMISSION
- 2. ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 3 *****
4 ADVANCED REACTOR DESIGNS SUBCOMMITTEE 5
6 U.S. Nuclear Regulatory Commission 7 Two White Flint North 8 11545 Rockville Pike l 9 Room T2-B3 10 Rockville, Maryland 20852-2738 11 ,
12 Tuesday, March 31, 1998 l
13 The Subcommittee met pursuant to notice at 8:30 14 a.m.
15 MEMBERS PRESENT:
16 JOHN BARTON, Chairman of the Subcommittee 17 MARIA FONTANA, Member of the Subcommittee 18 THOMAS KRESS, Member of the Subcommittee 19 DANA POWERS, Member of the Subcommittee 20 ROBERT SEALE, Member of the Subcommittee 21 ROBERT-UHRIG, Member of the Subcommittee 22 GRAHAM WALLIS, Member of the Subcommittee 23 JAMES CARROLL, Consultant 24 IVAN CATTON, Consultant i 25 NOEL DUDLEY, Cognizant ACRS Staff Engineer i
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t 2
1 PROCEEDINGS
() 2 3 CHAIRMAN BARTON: Good morning.
[8:30 a.m.]
- The meeting will l
l 4 now come to order. This is a meeting of the ACRS 5 Subcommittee on Advanced Reactor Designs.
-6 My name is John Barton, Chairman of the 7 Subcommittee.
8 The ACRS Members in attendance are Maria Fontana, 9 Thomas Kress, Dana Powers, Robert Seale, Robert Uhrig --
10 Graham Wallis will join us this ,Iternoon and tomorrow. We l 11 also have in attendance ACRS Consultants James Carroll and l
12 Ivan Catton.
13 DR. CARROLL: Shouldn't the consultants come first 14 in this introduction?
) 15 CHAIRMAN BARTON: Tomorrow is the consultants 16 first day.
17 DR. CATTON: When they're older.
18 DR. CARROLL: Us old guys.
- 19 CHAIRMAN BARTON
- The purpose of this meeting is l
20 to hold discussions with representatives of the NRC staff 21 and Westinghouse Electric Company to gather information 22 concerning the AP600 advanced reactor design review.
23 Presentations will include items related to the 24 Westinghouse Standard Safety Evaluation Report and the Staff 25 draft Final Safety Evaluation (FSER) chapters 2, 9, 9A, 10, O ANN RILEY & ASSOCIATES, LTD.
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- 1 12, 13, and 15.
() 2 The Subcommittee will gather information, analyze {
3 relevant issues and facts, and formulate proposed positions 1
4 and' actions as appropriate for deliberation by the full f 5 Committee.
6 Noel Dudley is the Cognizant ACRS Staff Engineer !
7 for this meeting.
8 The rules for participation in today's meeting 9 have been announced as part of the notice of this meeting 10 previously established in the Federal Register on March 17, i 11 1998.
12 A transcript of the meeting is being kept and will 13 be made available as stated in the Federal Register notice.
14 It is requested speakers first identify themselves and speak
() 15 with sufficient clarity and volume so they can be readily 16 heard.
17 We have received no written comments or requests 18 for time to make oral statements from members of the public.
- l. 19 Copies of the SSAR chapters under review were sent L 20 to Subccmmittee Members.
21 Subsequently, Westinghouse issued revision 21 to 22 the SSAR on March 13, 1998. A change roadmap has been 23 provided to each Subcommittee Member, and an up-to-date copy 24 of the SSAR is available in the front of the Committee room 25 on the desk in the right-hand corner.
i l
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4 1 You also have in front of you a copy of the ACRS
() 2 open questions regarding AP600. Some of those questions may 3 get answered or responded to by Westinghouse during this 4 meeting.
5 We'll now proceed with the meeting and I call 6 upon Mr. Brian McIntyre of Westinghouse to begin.
7 MR. McINTYRE: Okay. Thank you, Mr. Barton.
8 We do have, for those questions that you mentioned 9 that are relevant to the specific chapters we're talking 10 about today, they will be answered during the session.
11 We have not had the advantage of seeing the staff 12 FSER drafts that have been provided to you. So, if you say 13 that, well, somewhere in here the staff said this, we're not 14 aware of that, and so, bear with us, and you may have to
() 15 explain that.
l 16 The way we're going to do the presentation today 17 is the same way we did the last one. We have what we 18 consider to be the chapter authors here today. They're 19 considered to be the experts in those specific areas, and 20 with that, Richard Orr is the chapter author for Chapter 2, 21 and he will make the presentation for Westinghouse.
t 22 MR. ORR: My name is Richard Orr. I'm an advisory 23 engineer with Westinghouse. I've been involved in the l 24 development of AP600 ever since it started.
25 Today I'm going to cover material in Chapter 2 of I
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5 1 the Standard Safety Analysis Report related to site
( 2 characteristics.
'3 DR. CATTON: When did AP600 actually start? When 4 did it actually start?
5 MR. ORR: I believe I've been involved in it since 6 the late '80s. It developed initially from a study of a 7 10-mega-watt plant that was then sort of the basis for many 8 of the safety systems that were then extrapolated up. The 9 AP600 itself started in about 1990, would it have been, or 10 '89?
11 MR. McINTYRE: We had a conceptual design study 12 from EPRI and the utilities that started in '85. In '89, we 13 got the contract to take that conceptual design to the 14 design certification, and then, in 1991, we got the
) 15 first-of-a-kind engineering to do the next level of 16 engineering work on the balance of plant.
17 DR. CATTON: So, about 1990 is when it really got 18 underway.
19 MR. McINTYRE: Well, in earnest. The detailed 20 engineering program actually started probably, I would say, 21 in '85 '86-type time-frame.
22 DR. CARROLL: As long as we're talking history, I 23 guess I have a question, probably for the staff.
24 Have the ABWR and System 80+ designs been through 25 the whole certification process now, or is that still O ANN RILEY & ASSOCIATES, LTD.
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1 underway?-
2 MR. WILSON: Jerry Wilson, NRR.
3 Both of those designs have completed the 4 certification process, and their design certification rules 5 went into effect in May of 1997.
6 DR. CARROLL: Okay. I guess I remember that.
j- 7 DR. SEALE: I have another question.
8- A very significant input to these der!gns, all 9 three of them, actually, not just this AP600, were the 10 requirements in the Utilities Requirement Documae., and I 11 was wondering if you were -- as you go long, would identify 12 the places in the URD where those particular elements are 13 stated, so we can sort of cross-check what you came up with 14 with, let's say, the wisdom of the industry, as reflected in 15 those -- in that document.
16 MR. ORR: I will attempt to cover that. I believe j 17 the material I'm going to present on the sort of site )
! 18 parameters is, I believe, almost identical to the Utility 19 Requirements Document, almost identical to what you may have
( 20 heard on ABWR and System 80.
l 21 DR. SEALE: That "almost" can be tricky sometimes.
l 22 MR. ORR: The reason I said "almost" is I don't 23 want to say it is identical, because then you might point 24 something out thao's just a little different.
25 DR. SEALE: That's one extreme.
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1 MR. ORR: Okay.
() 2 3
The standard format for safety analysis reports basically designated Chapter 2 for site-related information.
l 4 Now, for a standard plant, we have not yet 5 designated a site.
6 So, this chapter becomes a definition of site 7 parameters that are used in the design of the standard 8 plant, and at the time of a COL application, the applicant l 9 comes in with the site-specific information and demonstrates 10 that his site is suitable for the AP600.
11 The site parameters are identified in a table in 12 the -- in Chapter 2. They are also included in the 13 certified design material.
14 What I plan to do is to walk you through the site
() 15 parameters and give a little bit of background on the values l 16 and how they are used.
17 The chapter and the table specifically in that 18 chapter define site parameters used in the design. They 19 were selected based on sort of a review of expected sites in 20 the U.S., particularly existing sites where there are 21 already nuclear power plants, and the parameters selected 22 envelope most potential sites.
23 We believe that sort of 80 to 90 percent of the 24 site:s out there where there are existing nuclear plants 25 would, ir.doed, fall within these set of site parameters.
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8 1 DR. CARROLL: Okay. So, west coast sites are
() 2 eliminated.
3 MR. ORR: We have specifically -- I was just about 4 to go on to that. We have excluded certain ones, 5 specifically west coast, by the limitation on the seismic 6 magnitude to .3 g.
7 DR. CARROLL: Can you name the other ones -- other 8 existing sites in the east?
9 MR. ORR: The only other one that I'm aware of is 10 a site like Waterford, where there was very, very soft soil, 11 DR. CARROLL: Liquefaction?
12 MR. ORR: Not so much liquefaction as poor 13 bearing.
14 My background -- I worked on the floating plant
() 15 long ago, and I tell people Waterford is the only floating 16 plant that was built. They dug a hole deep enough that the 17 material removed equals the weight of the plant. And so, 18 although one might be able to improve a site like that 19 sufficient for AP600, it would be a major undertaking, and 20 right now, we would not consider that that is a suitable 21 site.
22 CHAIRMAN BARTON: Have you eliminated east coast 23 sites through the hurricanes? Because I look at your table 24 and the wind design is 110 miles an hour, but the tornado 25 wind design is higher. Does that bound a Category 5 ANN RILEY & ASSOCIATES, LTD.
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9 1 hurricane? Does that bound a Turkey Point-size hurricane or
() 2 not?
3 MR. ORR: Yes, it does. Let me address that now, 4 although I had it later.
5 The design wind is, indeed, 110 mile an hour, and 6 that corresponds to a 100-year occurrence. The tornado is l 7 approximately a million-year occurrence. The wind speed is 8 300 miles an hour.
9 We have also designated -- and this is for 10 specific post-72-hour recovery scenarios -- a Category 5 11 hurricane which has a peak gust at 200 miles an hour, and 12 that is used -- it does not affect the design of the nuclear 13 island, because the nuclear island is controlled by the 14 tornado, but there are certain items of equipment that are 15 designed only for the 200-mile-an-hour hurricane.
16 DR. CARROLL: Back to seismic parameters, how 17 about foreign sites? Would this plant be licensable in 18 Japan, for example?
- 19 MR. ORR
- It would require re-analyses, because I 20 believe all of the Japanese sites -- about the lowest 21 seismic level I've seen is at about .45 g. Some of them are 22 up at .6 g.
l 23 With relatively minor changes, yes, it would be l l
24 applicable in Japan, but the design that is being certified, l l'
25 no, that design would not be directly applicable in Japan.
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I 10 1 DR. CARROLL: Okay. Well, how about -- with these
() 2 re-analyses, how about Diablo Canyon?
3 MR. ORR: With re-analyses -- I don't think it is 4 then an AP600, but with re-analyses, with potentially some 1
! 5 increase in wall thicknesses, with additional reinforcement, 6 with equipment procured to a higher seismic level, yes. I l 7 mean the basic concept certainly can be applied.
l 8 DR. CARROLL: All right. Even with that sloshing 9 water tank up on top of the containment.
l 10 MR. ORR: Yes. I suspect that there are portions 11 of that roof that would be a little bit -- need to be a l 12 little bit thicker.
13 DR. CARROLL: Okay.
( 14 MR. ORR: In Chapter 2 of the SSAR, we discuss the
) 15 site parameters. We, in many cases, discuss how they are i 16 used in design and how the combined license applicant has to l 17 provide the site-specific information to show that he is j 18 within the AP600 site parameters.
i 19 Chapter 2 includes the normal five sections of the 20 standard format, and we also have three appendices.
21 The first portion on geography and demography is 22 almost exclusively site-specific information, and I don't 23 plan to spend time describing it.
24 About the only issue that affects licenseability 25 would be things like site access and population, and whether O ANN RILEY & ASSOCIATES, LTD.
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11 j 1 it's an AP600 or any other nuclear plant at the site, issues
, 2 are much the same.
3 The section 2.2 would discuss nearby industrial, 4 transportation, and military facilities. ,
l 5 Again, this is very much site-specific 6 information, and most sites would address these on a 7 probabilistic basis to show that, generally, the potential 8 accidents are sufficiently far away from the plant that they 9 would not impact safety.
10 The AP600 is designed for tornado and seismic, and 11 that provides inherent sort of ruggedness that can be 12 considered in these probabilistic scenarios of off-site 13 explosions and accidents of that caliber.
14 DR. CARROLL: Now, what's the criteria expressed 15 in annual core damage frequency that you have to meet?
16 MR. ORR: It is expressed in exactly the same 17 terms as the Standard Review Plan, and if I recall, it is 18 accidents shall be of a probability less than 10 to the 19 minus 6 per year, I think, of accidents leading to potential 20 core damage, and we have included that wording in the SSAR 21 as a requirement for the COL applicant to demonstrate that 22 his site is - - the probability of such accidents is below 23 this cut-off frequency.
24 DR. CARROLL: I am reading the words, but -
25 probability of severe consequences -- that's an undefined 1
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12 1 term. What does that mean?
() 2 MR. ORR: The core damage, off-site release --
3 DR. CARROLL: Okay.
4 MR. ORR: If I recall, there's a third one. I've 5 forgotten which one it is.
6 DR. CARROLL: Okay.
1 L 7 Now, does the 10 to the minus 6, in your mind, L
8 represent a risk-informed approach to dealing with these 9 issues?
10 MR. ORR: Yes.
11 DR. CARROLL: Okay. Suppose it was 10 to the 12 minus 8th. Would that be risk-informed?
13 MR. ORR: It would. The current sort of position 14 is that 10 to the minus 6 is acceptable. If I recall, it's
. )- 15 10 to the minus 6 on a -- which way is it? 10 to the minus 16 6 is on a best-estimate basis and 10 to the minus 7 is on a 17 conservative basis, if I recall the wording in the Standard 18 Review Plan.
19 DR. CARROLL: Okay. That Standard Review Plan 20 came about before we were conscious of risk-informed
( 21 regulation.
L 22 MR. ORR: It was almost the precursor to the
- 23 risk-informed regulation.
i 24 DR. CARROLL: All right. I 25 DR. CATTON: I just took a look at your section on
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13 1 meteorology, out of curiosity, and it really doesn't say
() 2 3
anything. It doesn't. It gives me a table.
what the temperature ranges are.
It tells me 4 MR. ORR: There are temperature ranges, there are 5 wind magnitudes, and there's chi over Q.
6 DR. CATTON: Where does it say something about
! 7 things'like a history of fumigation, the thickness of the l
l 8 mixing layer, and that kind of thing?
9 MR. ORR: That is all the site-specific
! 10 information that has to be provided by the COL applicant.
11 DR. CATTON: It seems to me that, in this l 12 specification, you would give some limits on those kinds of i
13 things, that you can't.have the mixing layer less than 100 14 feet for more than a certain number of days in a row and 15 that kind of thing. Where is that done, or is it?
l 16 MR. ORR: That is done in the -- it would be done i
l 17 in the' COL application. If it affects any of our analyses, 18 it would be considered in the analysis. I think the only l 19 parameter from the meteorology that is used in the accident 20 analyses is chi over Q.
21 DR. CATTON: So, do you make a statement about chi 22 over Q somewhere?
23 MR. ORR: Yes.
24 DR. CATTON: Where could I find that?
25 MR. ORR: It's in the table and it's in my ANN RILEY & ASSOCIATES, LTD.
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14 1 overhead in --
() 2 DR. CATTON: I'm looking at table 2-1, which is 3 what 2.3 calls out, and I don't see much of anything.
4 DR. CARROLL: Sheet 2 of 2, Ivan. Sheet 2 of 2 of 5 table 2.1 --
6 DR. CATTON: Sheet 2.
7 DR. CARROLL: -- gives atmospheric chi over Q.
8 DR. CATTON: Okay.
9 MR. ORR: I have it in a later overhead. We'll 10 get to it very shortly.
11 DR. CATTON: Okay.
12 MR. ORR: On meteorology, on hydrologic 13 engineering, and on the geology and seismology -- I'm going 14 to come back to the specific values in the site parameter 15 table.
16 Let me just mention, there are three appendices in 17 Chapter 2 that relate to a series of studies that we did on l 18 soil conditions and the seismic behavior of AP600 on various 19 soil conditions.
l 20 We used these studies as a basis to narrow down on !
21 the specific soil cases used in the design analyses for the t
22 AP600, and they support the interface that we have '
23 established in the site parameter.
i 24 Appendix 2A was our initial work on looking at 25 soil profiles for the AP600. Following rounds of discussion ANN RILEY & ASSOCIATES, LTD.
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15 1 with the NRC staff, we did supplemental analyses and
() 2 documented those in Appendix 2B, and finally,.we used that 3 information develop the lateral earth pressure loads on the 4 walls below grade, and so, that work is documented in l 5 Appendix 2C.
(
6 Temperature limits are established for the safety 7 analyses, and you'll see on the table two groups of air l 8 temperatures, one we have called maximum and minimum safety 9- that are used in the safety ana3yses, and we have also used 10 the identified maximum and minimum normal, and these 11 temperature ranges are used for the design of the -- for the 12 power systems, the power generation systems.
13 The maximum safety analyses use a 115-degree 14 temperature. This is basically the design basis analyses r
15 and ultimate heat sink with containment cooling.
16 The minimum safety'of minus 40 degrees affects 17 things like freeze protection of the tank up on the roof and 18 the minimum service temperature for the containment vessel.
, 19 DR. CARROLL: It-won't slosh in an' earthquake if 20 you freeze it. j 21 MR. ORR: It won't flow too well if you freeze it.
22 DR. SEALE: How exclusionary are these 23 temperatures? I mean, for example, the tropical areas of 24 the world.
25 MR. ORR: From the review of U.S. data, we believe l
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1 16 !
1 that these temperature extremes would not limit siting.
[)
U 2 DR. CATTON: You can't build one in Death Valley.
3 MR. ORR: It might exclude Death Valley, yes. It 4 might also exclude sort of some areas in the extreme north 5 of Minnesota, where they have prolonged periods less than 6 minus 40.
7 DR. CARROLL: The reason that wet bulb becomes 8 important is that the design must have a fuel cooling tower.
9 The reason we have wet bulb in here is because the design 10 requires a cooling tower for the cooling water for various 11 water systems in the plant.
12 MR. ORR: For the secondary side, yes, not for any 13 safety-related function.
14 DR. CARROLL: So, why is that in -- I
/~~
k) 15 MR. ORR: It affects slightly the air flow, the 16 air flow conditions on the outside of the containment !
17 vessel.
18 DR. CARROLL: Okay. But the design -- regardless 19 of where you site this thing, there's going to be a cooling 20 tower. Is that correct? l l
21 MR. ORR: Yes, that's correct. In the material 22 that's in the Safety Analysis Report, there is a cooling 23 tower.
24 DR. CARROLL: Okay. I l
l 25 MR. ORR: The next slide picks up the material l
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17 1 from the second page of the table that has the chi over Q l
() 2 3
values. These are established from a study of existing plant sites and, if I recall, are part of the utility 4 requirement document that has previously been reviewed.
5 These are used in the accident analyses to determine the 6 off-site effects.
7 DR. CATTON: So, these numbers are based on an 8 annual average of the meteorology. There's no admonitions 9 about mixing layers, inversions, or anything else. Is that 10 a correct interpretation?
11 MR. ORR: Brian, are you able to comment on that, l
12 or can I ask you to defer that question? There is a 13 presentation this afternoon on the accident analyses, and 14 they will be able to tell you what their views would be.
O)
( 15 DR. CATTON: Accident analysis is Chapter 15. I 16 saw nothing about it in Chapter 15. I-think this is the 17 place to raise the question.
18 MR. ORR: Okay.
19 DR. CATTON: We have some sites in this country 20 that have occasional inversions, and I think Jay knows all 21 about one of them, where chi over Q was just fine, and it's 22 the -- and what happens when you do a year-round average is 23 you just eliminate it, and I think that's a mistake.
24 I think there should be some admonition about such l 25 things as inversion layers, periods of stagnation, and these O ANN RILEY & ASSOCIATES, LTD.
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1 kinds of things, and there's nothing here, and there are I
() 2 lots of bad sites you could pick, like Merced, California, for example, that's at up to 45 days of stagnation, yet its i
! 3
{
4 year-round chi over Q average calculated with some sort of 5 dispersion would be just fine.
6 DR. POWERS: Your number in the table labeled zero 7 to two hours -- is that intended to mean the worst two hours 8 that occurs in the year? That would certainly help.
9 MR. ORR: Unfortunately, although I did all of the 10 -- of Chapter 2, this particular portion on chi over Q is 11 the portion that is done by someone else.
12 DR. POWERS: Wouldn't you know we'd ask questions 13 about that?
14 DR. CATTON: Unfortunate for you.
() 15 DR. POWERS: We had this call from a guy up in 16 Pittsburgh.
17 MR. ORR: He is making a presentation later today.
18 .That's why I was hoping that we could --
19 DR. CARROLL: Okay. Well, you're going to tip him 20 off that we have a few questions.
21 MR. ORR: I already tipped him off yesterday that 22 I might do this to him.
23 DR. POWERS: And his name is?
24 MR. ORR: Jim Grover. He's on the agenda, I 25 believe, for straight after lunch, if I recall.
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19 1 MR. McINTYRE: He's on his way as we speak.
() 2- DR. CARROLL: Maybe he wants to turn back.
3 MR. ORR: I'm glad ~I warned him yesterday.
4 I covered most of this in response to your 5 question earlier.
6 We have a design wind established at 110 miles an 7 hour for safety-related design. This corresponds to a l 8 recurrence interval of about 100 years.
9 For the non-safety functions, we have a 1.0 safety 1
10 importance factor, and this corresponds to about a 50-year 11 recurrence interval.
12 DR. CARROLL: What is the meaning of importance 13 factor? That's a new term to me.
14 MR. ORR: The importance factor -- this
) 15 terminology comes from the Uniform Building Code and the 16 ANSI document A58.1, and I believe it is on wind loads on l 17 structures.
18 It is a factor that is applied to the basic wind 19 speed of 110 miles an hour. So, in practice, you end up 20 with a wind speed of 110 times the 1.11 factor, giving you 21 about 122 miles an hour as the wind speed.
l 22 DR. POWERS: Why is a 50-year return period i 23 appropriate here?
24 MR. ORR: The basic wind speed is defined in the 25 standard codes, and this is the UBC or the ANSI document, in i
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l l
l 20
! 1 terms of the wind speed with a recurrence interval at 50 i
() 2 years, and that is what is used in most commercial dvsign.
l 3 DR. POWERS: But this is not most commercial 4 designs.
l 5 MR. ORR: For safety-related, we use the 6 importance factor of 1.1, which brings it up to a 100-year 7 recurrence interval, and in practice, it doesn't really 8 govern any of the safety-related structures, because they l
9 are controlled by the design for the tornado condition.
l 10 DR. POWERS: I guess I'm still struggling to 11 understand why we would use even a 100-year return period in !
12 defining the design basis.
I 13 MR. ORR: Strictly -- if you think of the design 14 basis as the maximum that occurs, no, you don't. The 110 t' ')
i 15 miles an hour is used as a normal -- as an event that is 16 expected during the life of the plant, and the stress levels l 17 are maintained at about two-thirds of yield for this l 18 condition.
19 DR. POWERS: But if you were -- when you set down 20 this idea that I am going to have this condition at least 21 once in the life of this plant, what is the probability l
22 level that you're looking for there? Wouldn't it be better l
23 to be about .1 as opposed to something like .3 that you have 24 here?
25 MR. ORR: With the stress levels that are used for I' ANN RILEY & ASSOCIATES, LTD.
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21 1 design, no, I don't think it matters.
() 2 3
DR. POWERS: You're covering safety with one parameter to cover something in another. I mean you ought 4 to have some consistency here.
5 MR. ORR: Well, the consistency -- this is the way 6 that the codes and standards normally do it.
7 .DR. POWERS: I understand that.
8 MR. ORR: They establish a wind level at 100 years 9 and a stress level that is aoout two-thirds of yield, 10 DR. POWERS: But nobody has put a gun to your head 11 and said you must conform with these and nothing else.
12 MR. ORR: That's right.
13 DR. POWERS: So, you had some freedom to choose 14 this.
() 15- MR. ORR: We had some freedom to choose this.
16 -DR. POWERS: And I'm just trying to understand why 17 you chose what you chose and not something else. An 18 acceptable answer is it's easier to do that than anything 19 else, because if you had come in with something else., I 20 would have asked you why didn't you go witn the Uniform 21 Building Code?
22 MR. ORR: I was going to come back with the other 23 answer, that this is what the Utility Requirements Document 24 says. It's.a similar answer.
25 DR. POWERS: And a perfectly acceptable one.
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1 22 1 DR. SEALE: But the real operative answer is that
() 2 the wir.d speeds associated with a tornado are considerably l 3 higher than these, and those are the ones that really limit
(
l 4 any structural --
5 DR. WALLIS: And are bounding.
6 DR. SEALE: -- yes -- characteristics.
7 MR. ORR: Right. Those are the ones that control 8 the safety-related design.
9 DR. WALLIS: Wind is just a uniform wind or 10 something? Don't you have to characterize the wind with 11 more than just speed?
12 MR. ORR: The 300 miles an hour?
13 DR. WALLIS: When it has fluctuations and sheer 14 and all sorts of things.
() 15 MR. ORR: Oh, yes. There's a whole host of other 16 parameters that go with it. That's one reason we tie back 17 to the normal wind design codes.
18 DR. WALLIS: This has a pedigree of lots of 19 studies of tall buildings in winds and things like that?
20 MR. ORR: Yes.
21 DR. WALLIS: It's all related to that?
22 MR. ORR: Yes. The 110 miles an hour corresponds 23 to what is called a fastest-mile wind speed.
24 DR. WALLIS: Well, if this thing is in the wake of l 25 something else, it makes a difference, and so on.
l l
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l 23 1
1 MR. ORR: If it's in the wake of something else, i
() 2 then there's some additional pressure coefficients that get 3 included in accordance with the building code.
4 DR. WALLIS: I see.
5 MR. ORR: There's different coefficient whether 6 it's windward, leeward.
l 7 DR. WALLIS: So, it's much more sophisticated than 8 you present here.
9 MR. ORR: Oh, yes.
10 DR. WALLIS: Okay.
11 DR. CARROLL: And will the combined operating 12 license reflect that? Will it tell you that it's more than 13 just 110 miles an hour with an importance factor of 1.11?
14 MR. ORR: The information that the COL applicant
() 15 has to provide is effectively the historical record of wind 16 speed and the magnitude with the -- of the basic wind speed 17 with the 50-year recurrence interval. This is measured at 18 10 meters above ground and typically away from the affected 19 buildings.
I 20 So, he will have the information from a series of 21 met stations in the surrounding community; he will have the 22 information from -- I think it's at least one year's worth 23 of data at his site.
24 DR. CARROLL: Okay.
25 DR. SEALE: So, historic is really not a very O ANN RILEY & ASSOCIATES, LTD.
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I 24 1 descriptive word.
() 2 3
MR. ORR: The information used in the building codes and the wind data for building codes is, indeed, based l 4 entirely on historical information which results, in fact, l
i l 5 in a series of maps of the U.'S. showing the 50-year 6 recurrence wind speed at each location in the U.S.
7 The tornado has a maximum wind speed of 300 miles 8 an hour.
9 DR. WALLIS: What's the density of the air?
10 MR. ORR: Pardon?
11 DR. WALLIS: The density of the air.
12 MR. ORR: The density of the air is taken the same 13 as for other wind calculations, and if I remember rightly it 14 ends up -- well, I'm not going to guess at it. It is l( ) 15 defined, though, in the wind curves.
16 Associated with the tornado, there is a reduction 17 -- a pressure reduction of 2 psi that is considered in the 18 design of enclosed buildings. There's a series of missi',es 19 that are postulated, and this is Spectrum 1 from the 20 Standard Review Plan, consisting of an automobile at 105 21 miles an hour, a 275-pound 8-inch diameter shell also at 105
- miles an hour 23 DR. WALLIS
- What is a shell?
24 MR. ORR: This is one that was put into the ;
25 Standard Review Plan, Spectrum 1.
l 1
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25 1 DR. WALLIS: Is it a military shell?
I)
\~J 2 MR. ORR: It's a military shell. It represents j 3 any hard missile such as sort of a pipe or --
4 DR. WALLIS: It's an explosive device?
5 MR. ORR: No.
6 DR. WALLIS: No.
7 MR. ORR: No. It is representative -- in some of 8 the other missile spectra, there are utility poles, there 9 are pipes, and as a simplification, about 10 years ago, in 10 the Standard Review Plan, 3.5.1.4, they designated these 11 three missiles with the velocitiec as a function of the peak l l
l 12 tornado wind speed.
13 DR. WALLIS: This is a one shot?
14 MR. ORR: One shell.
/%
(_,/ 15 DR. WALLIS: Only one shot? Only one automobile i 16 is allowed to be in the vicinity? One shot from one 17 automobile?
18 MR. ORR: In the design that we have done, we have 19 not taken any credit for sort of probabilistic --
20 DR. WALLIS: Multiple shots, I mean, multiple 21 shots by several automobiles.
22 MR. ORR: Yes. One wouldn't postulate them all at 23 the same location of the plant.
24 DR. WALLIS: Postulation is a strange game in this 25 field. This is something agreed to in the historical record I ANN RILEY & ASSOCIATES, LTD.
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26 1 of agreement with the NRC or something about --
2 MR. ORR: Yes.
- 3 DR. WALLIS
- -- the reasonableness of this?
4 MR. ORR: And all the exterior walls are designed 5 to stop these missiles.
6 DR. CATTON: They're careful where they put their 7 parking lot.
L 8 DR. CARROLL: Why is the one-inch-diameter steel 9 ball important?
10 MR. ORR: It is important for the evaluation of 11 openings through the exterior wall, things like HVAC inlets, 12 doors.
13 DR. CARROLL: Okay. Okay, i
14- DR. WALLIS: This hits a containment or a wall?
() 15 MR. ORR: Pardon?
{
16 DR. WALLIS: This hits a wall or the containment 17 building? It's the containment building?
l- 18 MR. ORR: No. There's an exterior concrete wall.
19 The shield building is three feet thick. The exterior walls 20 are a minimum of two feet thick. Tha roof is a minimum of l 21 15 inches thick.
22 DR. SEALE: And if it's made out of steel, it's l 23 about two-and-a-half-inch-thick shell.
24 MR. ORR: No. The containment vessel is i
i 25 inch-and-5/8ths.
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27 1 DR. SEALE: No, no, the shell that weighs 275 2 pounds.
3 MR. ORR: I'm not quite sure what the wall 4 thickness is. Effectively, it's a rigid missile.
5 DR. POWERS: When you do the analysis of the shell 6 impact, is it penetration you're looking for or just 7 spallation off the back side?
8 MR. ORR: Both.
9 DR. POWERS: Both.
10 . MR. ORR: Penetration, perforation, and scatter.
11 DR. POWERS: Okay.
12 CHAIRMAN BARTON: Richard, could yua hit the 13 highlights on the remaining slides? You've got six slides, 14 if I count right, and about 10 minutes to do them.
() 15 MR. ORR: Yes, certainly.
16 Let's take the bottom of this slide first, which 17 is the easiest one. Precipitation is established at very 18 sort of high levels for rain of 19.4 inches per hour, 19 corresponding --
20 DR. CARROLL: You haven't been in California this 21 winter.
22 MR. ORR: 6.3 inches in 5 minutes is a lot. And 23 the snow and the ice -- the 75 pounds per square foot is 24 representative of the site in the northern part of the U.S.
25 Now, the flood levels --
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28 1 DR. KRESS: I'm just curious -- I hate to take tinie, but why would you end up with a number like 19.4?
I() 21 3 MR. ORR: It comes directly out of a report that 4 was done, something like -- it's a hurricane report done by 5 NOAA, I believe, and there is a table that comes up with 6 exactly that number.
7 At one stage, if I recall, I had in the Safety ;
8 Analysis Report something like 6.2 inches in 5 minutes, and l 9 I was corrected by the NRC staff.
i 10 DR. KRESS: Okay.
f l 11 MR. ORR: The AP600 has two elevations below l 12 grade. We have a nominal grade at elevation 100. The 13 actual finished grade would just be a few inches below it.
- 14 That corresponds to a floor level inside the building.
15 DR. CARROLL: What d zero?
16 MR. ORR: We established 100 as grades so that we 17 didn't get negative numbers. That's the only reason. It's l
18 a nominal elevation 100 that corresponds to the floor level 19 at grade.
20 DR. CARROLL: Okay. I understand it now.
l 21 MR. ORR: If you establish zero as grade, you 22 worry about negative numbers.
23 DR. CARROLL: Your table doesn't explain that at 24 all. I scratched my. head for a long time. It's sheet 2 of 25 2.1.
l l \
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l 29 1 MR. ORR: Plant grade elevation is established as (O
m) s 2 plant elevation 100, as described a little bit in Chapter 2 3 and in all of the figures in Chapter 1 that shows the 4 general arrangement and Chapter 3 that shows the structural 5 configuration.
6 DR. CARROLL: I would think a footnote on sheet 2 7 of 2 of table 2-1 would be helpful, also.
l 8 MR. ORR: In table 2.1, we do have this note on 9 plant grade elevation, that it has to be less than plant 10 elevation 100. So, we are calling attention to it, and then i
l 11 you have to, indeed, go to Chapter 1 or Chapter 3 to find 4 i
12 what is plant elevation 100.
13 DR. CARROLL: All right.
f f
l 14 The requirements on flooding, firstly, is that
() 15 flooding at the site should be below grade, and this is all l 16 potential causes of flooding, probable maximum flood, 17 hurricane, dam failure -- I think those are the main ones. )
18 For design of the portion below grade, we consider 19 a groundwater table within two feet of the grade.
20 I think we have covered most of this.
21 We established the safe shutdown earthquake at .3
! 22 g, and yes, this does exclude certain California sites, and i l l
23 we established a response spectrum that is substantially the 24 same as Regulatory Guide 160. However, based on some l 25 studies that we did for east coast locations, we have
[
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30 l 1 amplified that response spectrum slightly at the high i
() 2 frequency, at 25 hz. The site must have no potential for 3 fault displacement or for liquefaction in an earthquake.
4 DR. WALLIS: Zero is hard to ever measure.
5 MR. ORR: That tends to be done a probabilistic 6 basis, yes. I've forgotten quite how the wording is, but it 7 is now discussed a little bit in the new 10 CFR Part 100 on
! 8 what studies have to be done to demonstrate acceptability of 9 the site.
l 10 The soil parameters of the site are significant
[
l 11 both for foundations and for soil / structure interaction in 12 the seismic analyses.
1 l
13 We established a bearing requirement of 8,000 i
l 14 pounds per square foot, is the average bearing load on the
() 15 soil for the footprint of the nuclear island.
16 We established a shear wave velocity -- and this, l
17 effectively, is the soil stiffness -- and say that the shear l
18 wave velocity must be greater than 1,000 feet per second.
l 1: This excludes the very soft sites but is representative of 20 the shear wave velocity that one would find at a site that l
21 can support these bearing leads.
22 And finally, we established a requirement on 23 variability of the soil below the plant. It's got to be l 24 fairly uniform, and this came out of quite a lot of 25 discussion that we had with the staff, and this slide is l
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I l
31 1 just a representation of what we're trying to accommodate.
() 2 3
On a real site, you can have situations where you've got a soil material on a rock material. The rock l 4 mate rial may slope or it may have a series of peaks and 5 valleys, and we have established criteria on the uniformity 6 of the soil primarily for bearing reactions on the base mat, l 7 but if we meet the interface, then we also adequately l 8 address the effect of this variability on the soil / structure l
9 interaction analyses.
10 DR. WALLIS: So, this criteria that you just 11 presented is quantified.
12 MR. ORR: The next slide is the quantification of 13 it --
14 DR. WALLIS: Okay.
() 15 MR. ORR: -- where we have identified two cases, 16 one for effectively a rock site, one for a soil site.
17 To get -- to have uniformity, we want each of the 18 soil layers to be of a fairly uniform thickness. We do not 19 want a dip, a very steep dip, and we don't want significant 20 variation along the layer, and we have picked 20-percent 21 variation for the rock site and 10 percent for the soil 22 site, which -- because the soil site can be more significant 23 to the foundation.
24 In some cases, in some sites, this may be 25 judgement, and so, we have also established some -- an l
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t 32 1 analytical approach that allows to make a quantitative I ['}
\_-
2 comparison of, is the effect of the site on the AP600 within 3 the limits considered in the design?
4 DR. WALLIS: Why don't you have a functional 5 requirement instead of all these details about what's got to 6 be in the soil?
7 MR. ORR: A functional requirement? l 8 DR. WALLIS: Presumably, this is to meet some "
9 functional requirement of holding up the building. Why 10 don't you have a functional requirement first?
11 MR. ORR: The functional requirement is, indeed, l
12 to hold up the building.
13 DR. ,iALLIS : That's all you need.
14 MR. ORR: The mat -- the building is already p)
( ,
15 designed. So, it has -- it assumes certain degree of 16 non-uniformity, and now what we have to do is to assure that 17 the site doesn't have a greater non-uniformity than has been 18 considered in the design.
19 DR. WALLIS: Why?
20 MR. ORR: Because in the extreme, you might 21 overload the base mat and have severe cracking.
22 DR. WALLIS: Then you should have a requirement on ;
23 the loading of the base mat.
24 MR. ORR: This is used as the basis for the 25 loading on the base mat.
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f 33 1 DR. WALLIS: Well, I think you see what I'm
() 2 getting at. It's a function that's to be met, rather than 3 the characteristics of the soil. You might use a different 4 base mat on different soil, all kinds of stuff.
5 MR. ORR: No. The standard plant has a design of 6 .the base mat. If it turned out that the soil were outside 7 the range, then it.is -- the standard plant is no Jonger 8 suitable, and indeed, the COL applicant would have to take 9 exception in some manner to the base mat design and say here 10 is the base mat design for my site.
l 11 MR. McINTYRE: Dr. Wallis, we're building a plant, i
12 we've designed a plant that will fit on many sites, and so, 13 we're looking to try to characterize the site. You're 14 right, there is a' functional requirement, and if you've got
() 15 a site, then there is a functional requirement to meet. It 16 does seem a little backwards compared to what one might i
17 think.
18 CHAIRMAN BARTON: Any other questions of Richard?
19 (No response.]
20 CHAIRMAN BARTON: Thank you.
21 Staff presentation on the SER in this chapter?
i 22 MR. KENYON: No, sir, we have no presentation.
I 23 You have our advance copy of the SER. The staff has gone 24 through their last revision, revision 21 to the SSAR, and we 25 have determined that they have made the changes that we O ANN RILEY & ASSOCIATES, LTD.
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34 1 expected, and we have no open items on this chapter.
2 CHAIRMAN BARTON: Any questions of the staff?
3 DR. WALLIS: Is that assumed to be acceptable, 4 then? How do we knov: that it's a good analysis? Because 5 you have no questions, it must be good? I'm just naive 6 about the process here.
7 MR. KENYON: We've written our SER, and we have l
8 accepted the design of the plant as described in Chapter 2-.
9 Yes, we've accepted it. All the issues that the staff have 10 identified have been resolved to our satisfaction.
11 DR. WALLIS: So, your conclusion is that there's 12 nothing about this that's worth further investigation by 13 this committee. Is that your conclusion?
14 MR. BAGCHI: No, sir. This is Gutan Bagchi. I'm 15 Chief of Civil Engineering and Geo-Science Branch.
16 There is a process in place, and there is a very 17 long history of licensing plants, and we have documented all 18 of thoue things in the regulation, in the Standard Review 19 Plan, and we say outright how we do the evaluation and 20 review.
21 There has been a very significant depth of review 22 on this plant, and if you look at our Safety Evaluation 23 Report, particularly when you come to Chapter 3, you will i 24- find a lot of interactions that have gone on.
25 But our test of goodness lies in meeting the ;
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35 1 general design criteria, meeting the regulation, meeting the
( 2 Standard Review Plan, meeting the industry standards and 3- acceptance criteria. So, those are all well-established.
4 Since we meet those, we made those conclusions in 5 the Final Safety Evaluation Report.
6 DR. CARROLL: Just to give Graham some idea, how 7 many requests for information did you f.ile on this 8 particular chapter?
9 MR. BAGCHI: I would not hazard to guess, even.
10 Many, many, many.
11 DR. SEALE: Would Westinghouse like to complain?
12 .R. McINTYRE:
M Westinghouse would like to comment 13 there's been over 7,350 questions asked.
14 DR. SEALE: Not about this chapter.
) 15 MR. McINTYRE: Not about this chapter. We don't 16 have it by chapter.
17 DR. SEALE: Okay.
18 MR. McINTYRE: But there have been a fair number 19 of questions.
20 DR. WALLIS: The reason that I am interested --
21 maybe we'll come back to it later -- is it's very difficult, .
I 22 it seems to me, for a committee like this to evaluate l
23 anything if all they hear is that the staff says it's okay, i i
24 unless you go back over history and say, well, these were
~
25 the real critical items'we have to worry about and get some O ANN RILEY & ASSOCIATES, LTD.
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l 36 1 perspective on what matters and what doesn't.
() 2 3
Now, I'm sure we can't do that today, but as a l newcomer to this process, I feel very concerned about sort i
4 of giving a' rubber stamp to the fact that you guys have no 5 complaints.
6 MR. BAGCHI: This is Gutan Bagchi again.
l 7 Sir, I have to assure you that you will find only
' J 8 in these chapters, Chapter.3, that the independent analysis 9 had been made by the staff and results verified by the 10 staff.
l 11 DR. WALLIS: Well, that could be wrong, too. How 12 do we know? That's the problem I have. I don't have any 13 check of reality on any of it.
14 DR. CATTON: And I think they treated the weather 15 inappropriately.
16 DR. CARROLL: But we'll get to that this 17 afternoon.
18 Graham, ACRS sort of playsfan audit role in this 19 process. We , obviously, don't duplicate everything the 20 staff does, but I think, from experience, ACRS members sort 21 of know what areas to probe in and what kind of questions to 22 ask. i i
l 23 But I certainly can't say that, when we sign off 24 of Chapter 2, we've done a thorough, line-by-line review of 25 everything that was ever done on Chapter 2.
l ,
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37 1 DR. SEALE: But in sup9 ort of Graham's comments, 2 in prior actions there was already a specific site in place 3 with presumably documented soil c onditions, earthquake 4 expectations, tornado potential, and all of these other 5 things for that particular site, and so, it was a question i 6 of whether or not the design was adequate for those 4 7 particular circumstances.
8 What we're doing now is taking the yield average 9 whatever and -- with the requirement, as you stated, that 10 the building von't fall down -- and now we've got an 11 analysis which purports to provide a building which won't l 12 fall down if it's built on that so-called average site, and i
13 the question is what are the likely weak spots in that i 14 particular analysis?
15 MR. ROTHMAN: Excuse me. I'm Robert Rothman. I'm f 16 the Section Chief of the Geo-Sciences section.
17 This chapter is a little bit different than a l 18 review of a design. What we did was we looked at the site 19 parameters that they proposed and the method by which the 20 COL applicant would demonstrate that their site met those 21 site parameters, and we specified the types of analyses and 22 the types of data that would have to be supplied in order to 23 match this design to the site, and we have a regulation that l 24 also specifies how you go about certifying a site, and so, 25 what we're doing here is mainly documenting this is what the l
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38 1 COL applicant has to do to certify the site that it falls i- ~
fv) 2 within the envelope of the design. I 3 DR. CARROLL: And ACRS would review that at the 4 COL stage.
5 MR. ROTHMAN- Yes, that's right.
6 DR. SEALE: So, you're setting the level of the 7 bar, and the bar still has to be jumped over.
8 MR. ROTHMAN: The licensees set the level of the 9 bar, and they picked the seismic design, they picked the 10 load-bearing capacity. We said you have to do the following
{
11 things to show that that bar is suitable for your site, or 12 your site is suitable for that bar.
13 DR. KRESS: It seems to me like the ACRS role 14 would be, given these site parameters, is the plant designed "N
1
,/ 15 to be safe under those conditions, and that, I think, you j 16 know, has very little to do with Chapter 2. It's some other 17 chapter, j 18 DR. WALLIS: I have this question on ever*' chapter 19 but not on this chapter particularly.
20 DR. KRESS: It's a question that's been around for 21 a long time.
22 CHAIRMAN BARTON: Are you ready, Donald, Chapter l 23 10?
l l 24 MR. HUTCHINGS: Yes. Can you hear me?
25 My name is Don Hutchings. I work for f% ANN RILEY & ASSOCIATES, LTD.
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i l
39 l
1 Westinghouse, and I'm here to talk about Chapter 10, which
() 2 is the steam and pcwer conversion systems.
3 Since there is a significant number of things'in 4 Chapter 10, what I want to do first is just show an overview 5 slide of what I propose to go through here. I'll show you 6 something on the SSAR content, a little bit of information 7- on the' turbine cycle information,-some information on the 8~ turbine generator itself, then we'll talk about the main 9 steam supply systems and the condensate and feedwater 10 systems, some of which -- of those two systems -- is 11 safety-related. Then we also have the main condenser and 12 then other support systems and then some conclusions.
13 Also, in the hand-outs, you'll see that there.is 1
14 some bold information, and really, the process that I'm
() 15 trying to bring out with those bold comments are things that 16 are significant, not that other things are insignificant, 17 but they are significant things or they may be things that 18 are slightly different than past practices.
19 Essentially, Chapter 10 of the SSAR has a summary 20 description of the steam and power conversion systems, and 21 then 10.2 talks about the turbine generator, and then we -
22 talk about the main steam supply systems and then the other
'23 features for the steam and power are covered in 10.4. That 24 would be like the feedwater systems and some of these other 25 systems that I was talking about.
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j i
40 l' This is the basic information about the turbine
() 2 3
cycle.
AP600 is basically a 1,940 mega-watt thermal 4 reactor output, which equates to basically 675,000-kilowatt 5 turbine. We have one high-pressure turbine and two j 6 low-pressure _ turbines, and we have seven stages of feedwater 7 heating and four stages of low-pressure heating, and then
! 8 the plant also uses a deaerator, which some nuclear plants 9 do but most don't, I guess.
10 We also have two pressures of high-pressure -- two 11- stages of high-pressure heating, and the heat rate of the 12 plant, as noted there, is around 9,800 and '.2 btu's per 13 kilowatt hour, and that's all based on a design back I
. 14 pressure in the condenser of two-and-a-half inches of
() 15 mercury absolute.
16 DR. CARROLL: Why two-and-a-half inches? There's 17 an awful lot -- our ocean sites, typically, would have much 18 lower back pressure.
19 MR. HUTCHINGS: The plant and the turbine can go 20 down significantly lower than that, it can go down -- and 21 probably still generate higher outputs at maybe as low as 22 one inch.
23 However, that's just a reference point that was 24 picked, because on a normal condenser cooling tower design 25 with the site -- standard site parameters picked, that's a ANN RILEY & ASSOCIATES, LTD.
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41 1 reasonable value that's economically a reasonable trade-off.
() 2 3
DR. CARROLL: Why the decision to go with a deaerator in the feedwater system?
4 MR. HUTCHINGS: I don't know the exact reason for 5 that. It was actually before my time in being there. I 6 know from my experience in fossil plants that they typically l
7 use deaerators because it does a very good job of removing 8 oxygen.
I 9' In nuclear plants, they've typically done it 10- through the condenser.
I 11 This plant also does -- you know, in condensing, I 12 you do remove oxygen, but I believe it can get to lower 13 levels here, and I think that it would improve the overall t
14 lower levels of oxygen in the system, therefore, you know, l
() 15 creating less steam generator problems down the road.
16 DR. CARROLL: Okay.
17 MR. HUTCHINGS: Some highlights on the turbine 18 generator. It's designed for both base load and for 19 load-follow operations. That's consistent with the URD 20 requirements that they have asked for.
21 DR. CARROLL: Now, is the 30 percent to 100 I
i 22 percent range -- that's the Utility Requirement Document for l I i 23 load-follow? i 24 MR. HUTCHINGS: Yes, it is.
25 DR. CARROLL: Is there any constraint that !
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1 42 1 prevents you from going lower than that?
2 MR. HUTCHINGS: No. Actually, the plant can take '
[x_)D 3 -- once you start getting below around 30 percent, the plant 4 will operate, but you'll start to drop off on efficiencies.
5 Part of that has to do with the way the draining 6 systems on the feedwater heaters operate, but the plant can 7 operate at lower levels than that. It can operate as low as 8 holding the house loads, which would be on the order of 5 to 9 10 percent range.
10 DR. CARROLL: Okay.
11 MR. HUTCHINGS: It satisfies NRC requirements 12 related to breaks in high-energy and moderate-energy piping 13 systems outside of containment.
14 We provide the extraction steam off the turbine,
()
f-m 15 as noted on the first slide, and basically, the turbine 16 generator is located in the turbine building, which should 17 be obvious, and we have a probability of destructive 18 over-speed of less than 1 times 10 to the minus 5th per 19 year, which is consistent with the industry practices and 20 NRC requirements, and -- :
21 DR. CARROLL: I notice that you state that the 22 low-pressure turbine rotors are going to be bored but not 23 the high-pressure turbine rotor and rot the generator rotor.
24 What's the rationale for not boring? '
25 I happen to be a great believer of boring since I l
[)
(_)
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43 1 helped pick up the pieces from the Pittsburgh number one
() 2 generator rotor failure in 1954.
3 MR. HUTCHINGS: I don't know the answer to that i
l 4 question.
l l 5 DR. CARROLL: And the reason that happened was 6 that, at that point in history, the metallurgists thought 7 they were smart enough to get clean enough forgings to I 8 eliminate the need for boring.
9 MR. HUTCHINGS: I really don't know the specific i
! 10 answer for that. That information really came from 11 Westinghouse turbine divisions, and that's their 12 recommendations. I don't know the specifics as to why they i
13 don't choose boring on those. That's their standard 14 practice for both commercial and nuclear plants at this
() 15 time.
16 DR. CARROLL: Okay.
17- During the lunch hour, could somebody get a more 18 definitive answer from those tracters?
i 19 MR. McINTYRE: We cv y 20 DR. CARROLL: Okay.
21 MR. HUTCHINGS: I guess the last --
22 DR. CARROLL: When a generator rotor at 3,960 rpm 23 breaks in half and slows to zero in less than one 24 revolution, a lot of energy is dissipated.
25 MR. HUTCHINGS: Yes. Well, the last item, which O ANN RILEY & ASSOCIATES, LTD.
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44 1 is --
() 2 DR. CARROLL: Yes, I know.
3 MR. HUTCHINGS: Obviously, the point is, God '
4 forbid, a turbine or a generator should fail, the object l
5 here, of course, is to throw the parts away from the 1
6 safety-related portions of the plant.
7 DR. FONTANA: I take it that's a case where the '
8 item is important but not different from prior practice.
l 9- MR. HUTCHINGS: Yes, I believe that's correct. I
)
10 don't know if there are any plants that are the other way --
11 I'm not an expert -- but most plants -- most modern plants i
12 are designed that way.
13 DR. CARROLL: There are a few that oriented wrong.
14 MR. HUTCHINGS: A little bit information on the 15 turbine generator -- essentially, the last stage of the j 16 low-pressure turbines is 47-inch blades on it, and the
! 17 operating speed is 1,800 rpm, and then there's some 18 information there giving you the ratings on the generator l 19 and the operating information on it.
p l 20 DR. UHRIG: They're not shrouded blades. They're 1
21 stand-alone blades?
22 MR. HUTCHINGS: I know what you're asking. I l
23 think they're not shrouded. l 24 DR. UHRIG: That's what I recall.
l 25 MR. HUTCHINGS: I believe that's correct.
i i
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45 l
(
1 We have a moisture separator re-heater, which, of
() 2 course, because in a nuclear plant of this type, we don't L 3 use super-heated steam, so you want to, after you run 4 through the first high-pressure turbine, separate the I
5 moisture before entering the steam into the low-pressure l 6 turbines, and the turbine over-speed protection -- there's a 7 mechanical and an electrical or electronic, depending on the i
8 terminology, over-speed -- at 110 percent of the rated i
9 over-speed, the mechanical device would be used to close the 10 turbine stop valves and re-heat valves, and at 111 percent, 11 there's an electrical system _that also is used to keep the l 12 turbine from over-speeding.
13 DR. UHRIG: There's also a 103-percent --
14 MR. HUTCHINGS: That's a control.
) 15 DR. UHRIG: -- control.
16 MR. HUTCHINGS: Yes.
17 DR. UHRIG: But it says that it closes the control i
18 and intercept valves at that point.
19 MR. HUTCHINGS: It biases them towards the closed 20 direction to start the turbine to slow down, correct, but 21 those are not -- I only separated these because it's l 22 actually -- this is a separate over-protection control.
23 That's part of the normal control system at 103.
24 DR. UHRIG: All right.
25 DR. CARROLL: That's conventional, f) v ANN RILEY & ASSOCIATES, LTD.
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46 y 1 MR. HUTCHINGS: Right. And the turbine is t L
() 2 3
designed, in these events, not to go over a speed of a maximum of 120 percent of the rated speed. 1 4 DR. UHRIG: I'm.trying to remember. As I recall, t
5 you have a frequency control on this, also. There's an 1
6 under-frequency trip at about 59.7 or something, if it gets I
7 pulled down there. Do you have an over-frequency trip l l
\
l 8 that's comparable to that or you don't worry about that?
9 MR. HUTCHINGS: I believe there's only an 10 under-frequency trip, and that's because you've got like l 11 your main coolant pumps -- there's a lot of things that run
! 12 off of that frequency, so you get into low-flow situations i 13 and you might want to trip the plant to make it come down. L 14 DR. UHRIG: You don't worry about the higher l 15 speed.
l 16 MR. HUTCHINGS: I believe that's correct.
17 DR. CARROLL: Well, in addition to that, you've 18 got a concern about turbine blades running under-frequency.
j 19 . MR. HUTCHINGS: Right.
I 20 DR. CARROLL: Where is that under-frequency trip?
21 Do you know?
22 MR. HUTCHINGS: The set-point?
23 DR. CARROLL: Yes.
24 MR. WINTERS: This is Jim Winters. I believe it's !
25 less than 90 percent, so it's 54. !
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i i
47 l' MR. HUTCHINGS: I think it's 54. I believe that's
( 2 the correct number.
l 3 DR. UHRIG: You're way out of synchronization at 4 that point.
l 5 MR. HUTCHINGS: Yes.
6 MR. WINTERS: Right. If you're on the grid, it's 7 very hard to do that, but if you're off the grid, you do 8 that to protect your in-house pumps.
l 9 DR. CARROLL: In a bad system upset, you can pull I 10 a generator down.
11 MR. WINTERS: Right. If the grid pulls the 12 generator down, it will trip. I l
l 13 DR. UHRIG: 59.7 is the number I remember.
14 DR. CARROLL: No.
() 15 MR. WINTERS: No. Ours goes much less than that.
l 16 DR. UHRIG: Gay . ;
17 MR. WINTERS: The 59.7 is what the utility has so l 18 that you don't feed bad frequency into the grid. The plant i
19 safety analysis is based upon 10 percent.
20 DR. UHRIG: Thank you.
21 MR. HUTCHINGS: Okay.
l 22 This next slide talks about our main steam supply 23 system.
24 Basically, this is where we supply steam from the 25 steam generators over to the high-pressure turbine. It also ANN RILEY & ASSOCIATES, LTD.
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l 48 1 supplies steam to the moisture separate re-heaters. We also
() 2 have in this system a -- the capability if the turbine -- to 3 do a turbine by-pass of 40 percent of the steam directly to 4 the condenser, and the last item is that this system is 5 qualified to che leak-before-break criteria for the piping 6 system.
l 7 DR. CARROLL: Now, last time, we learned that the 8 staff did not accept your analysis for leak-before-break on, 9 what, the feedwater?
10 MR. HUTCHINGS: Correct.
11 DR. CARROLL: And they are going to come back and 12- explain to us -- somebody is going to come and explain to us 13 why that is when Bill Shack is here?
14 MR. KENYON: Yes, we will have somebody available.
15 CHAIRMAN BARTON: We can have that addressed at 16 the full committee later this week, when --
17 DR. CARROLL: That would be good.
l 18 CHAIRMAN BARTON: -- if Tom is prepared and Shack 19 is here.
20 MR. KENYON: The leak-before-break is a Chapter 3 21 item. We're not prepared to discuss Chapter 3 today.
! 22 CHAIRMAN BARTON: We'll put it on a list of open 23 questions from the committee, then.
' l i 24 MR. HUTCHINGS: That will come up on the slide 25 when we get to the feeC1ater, also.
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l 49 1 DR. CARROLL: Okay.
(f 2 MR. HUTCHINGS: The only thing I point out here 3 is, in the main steam supply system, we have main steam 4 isolation valves and the by-pass valves and the safety 5 valves and the power-operated relief block valve are 6 safety-related, which means they're all on the nuclear 7 island, all of our safety-related stuff. There's nothing 8 outside of the nuclear island.
9 DR. UHRIG: Before you go on --
10 MR. HUTCHINGS: Yes.
11 DR. UHRIG: There's one statement here that I 12 didn't understand. Maybe you could clarify it. It has to
'13 do with load-following. Are you at that point?
14 MR. HUTCHINGS: Okay.
h 15 DR. UHRIG: It says, for the AP600, its 16 load-following capability is maintained for more than 90 17 percent of the cycle life. I didn't understand what that 18 meant.
19 MR. HUTCHINGS: I'm not quite sure.
20 DR. CARROLL: The answer is, at the end of the 21 cycle, you can't process borated water.
22 DR. UHRIG: Okay. It's the fuel cycle that 23 they're talking about. That's what I didn't understand.
24 Okay.
25 MR. HUTCHINGS: Yes.
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50 1 DR. UHRIG: You do have a load-following l
() 2 capability in this machine --
3 MR. HUTCHINGS: Yes.
4 DR. UHRIG: -- in the AP600.
5 MR. HUTCHINGS: Yes.
6 DR. UHRIG: This normally is limited by the fuel.
7 So, what you're saying is that for 90 percent of the fuel 8 cycle life --
9 MR. HUTCHINGS: Right.
10 DR. UHRIG: Okay.
11 MR. HUTCHINGS: -- we can do the load-following --
12 DR. UHRIG: Thank you.
13 MR. HUTCHINGS: -- to the curve that's provided in 14 the URD.
) 15 DR. CARROLL: And you can do some load-following l 16 --
17 MR. HUTCHINGS: We can do some beyond that, just 18 not to what the requirements in the URD state.
t 19 DR. CARROLL: Okay.
l 20 MR. HUTCHINGS: The next system -- this is really 21 the condensate feedwater system.
22 What we have here is we have -- our feedwater 23 pumps and our condensate system are in the turbine building, 24 and then the rest of the feedwater system goes across to the 25 nuclear island and into the containment to supply the steam O ANN RILEY & ASSOCIATES, LTD.
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I 51 1 generators. ,
() 2 .The non-safety-related portions of the main 3 feedwater system are in the turbine building, and all the 4 safety-related thing, again, is on the nuclear island.
5 That's the. main point I was trying to show here.
i 6 Our feedwater system is excluded from the 7 leak-before-break. However, I think that it is a point that
.8 we still designed it to the same criteria.
9 What we don't have -- I believe there's some 10 thermal monitoring that goes along with requiring to do 11 leak-before-break detection completely, and we don't have
~ 1:2 that in this feedwater system, since we're not really doing 13 a leak-before-break, but the stresses, the analysis, all of 14 that is -- that is the design of the feedwater system.
k 15 DR. CARROLL: Now, I got the impression last time 16 you wanted this to be a leak-before-break system and the 17- staff turned you down.
18 MR. HUTCHINGS: Yes, that's a correct statement, I 19 believe.
20 DR. CARROLL: Okay.
21 There were concerns -- we're designed to minimize l
E 22 water hammer. We followed the recommendations along that i 2:3 line. The staff had questions along this -- that's the main j' 24 reason I highlighted it. It was just that we did a number 25 of things to address those concerns.
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i 52 1 DR. CARROLL: Ivan wants to know what designed to
() 2 reduce water hammer is or minimize water hammer.
3 DR. WALLIS: Well, I think the word " minimize" is 4 meaningless. It occurs several times in these documents, l
5 and it's a meaningless term unless you describe constraints 6 and various other things. What's being minimized?
7 So, you have done something to reduce what you 8 think is the cause of water hammer, but " minimize" doesn't l 9 mean anything. What have you really done?
l 10 MR. HUTCHINGS: Well, steam generator has, for 11 example, two separate nozzles, one for the start-up line, -
12 one for the main line. The main line is a much bigger 13 diameter pipe, obviously.
14 DR. WALLIS: So, you've made a technical analysis
() 15 of the possible precursor events'to water hammer, and you've l 16 determined that the probability of water hammer is less than 17 something or what?
18 MR. HUTCHINGS: Well, I'll say that there's a 19 number of papers, documents, recommendations that come from 20 various sources to say, if you want to minimize the effect 21 of water hammer in feedwater systems, for example --
22 DR. WALLIS: You've done something to reduce water 23 hammer, but it's obscure what you mean.
24 MR. HUTCHINGS: Okay. On our main feedwater 25 system, for example, the main nozzle that would go in is a l
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53 1 very big nozzle. If you were to drop below, let's say --
!rx
!( I'm going to pick a number which may not be technically 2
l w -)
3 correct, but 5 percent or 10 percent flow through that main 4 feedwater nozzle, you can start to have stratification l 5 within the pipe, okay?
l 6 Wel3 , the one way to eliminate that is to have a 7 separate nozzle entrance into the steam generator that's 8 much smaller, so stratification doesn't occur.
l 9 DR. WALLIS: So, you have eliminated the causes of 10 water hammer? Is that what you mean?
l 11 MR. HUTCHINGS: Well, what we've done is we've --
12 if that was one of the causes, we've gone to things to 13 improve -- I want to use the word " minimize," because we can l
l 14 never say absolutely it won't happen.
!t')
l 't ,, 15 DR. WALLIS: Well, I guess I'm saying that the l 16 word " minimize" means nothing to me and shouldn't be used in 17 this report, and something that is more meaningful should be 18 used.
19 MR. HUTCHINGS: Well, we've incorporated features j 20 based on recommendations from various sources.
21 DR. CATTON: What sources?
22 MR. HUTCHINGS: Well, there are reports, for 23 example, that are written --
24 DR. CATTON: What reports?
25 MR. HUTCHINGS: -- from INPO -- I don't have the l' ANN RILEY & ASSOCIATES, LTD.
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l-54
'l references with me. They would be INPO reports. There were 1
()
- 2. URD, EPRI reports. There's feedback that Westinghouse gets t
l 3 from its operating plants that explains situations in which 4 water hammer would occur, and what we've done is to look and 5 evaluate that information and to make design changes so that 6 those same scenarios don't occur.
L '7 DR. KRESS: I think I agree with Graham. The word 8 " minimize" is just meaningless to us. We don't know what it L 9 means. So, whenever you put something like that up, we t
l 10 don't really know what it means, and what you just said.is a
- 11. better statement'of what you did.
12 DR. CATTON: There was a paper by Peter Griffith.
13 Actually, it was a Master's thesis. It actually won the 14 ASME heat transfer award for that particular year, and they l I.
k) 15 laid down some rules. Did you meet those rules for avoid 16 water hammer, steam condensation water hammer? That's why I 17 asked you what reports. If I were you, I would have at 18 least cited that one.
19 DR. WALLIS: And even those rules are just 20 guidelines. They don't reduce the possibility -- 1 i
! 21 DR. CATTON: It doesn't go to zero, no. l 22 DR. WALLIS: It doesn't go to.zero.
23 MR. HUTCHINGS: I'm kind of caught in a Catch-22. ;
24 DR. WALLIS: You're not going to be able to get 125 into the details. I just think you should never use the O ANN RILEY & ASSOCIATES, LTD.
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.1
55 1 word " minimize" about anything, not necessarily water 2 hammer.
3 DR. SEALE: It's the old buying and selling. It's 4 reducing water hammer.
5 MR. HUTCHINGS: Yes.
6 DR. CATTON: There was a lot of concern about 7 water hammer in the AP600, particularly after you ran your 8 Oregon State tests.
9 DR. HALLIS: You could change the word " minimize" 10 to " reduce the probability of," but then we'd come back and 11 ask you what is it.
12 DR. CATTON: But there still should be a design 13 . basis for making sure that it is reduced as much as you can, 14 and there should be some statement of that design basis
- 13. somewhere.
16 DR. WALLIS: Well, "as much as you can" is also 17 not acceptable. It's "as much as is needed" in order to 18 meet some specification.
19 MR. HUTCHINGS: Well, there is testing that's even 20 discussed in the report as part of the start-up procedures 21 that would show that the plant does not suffer from water 22 hammer problems.
23 DR. CARROLL: I think basically what they've done 24 is look at the history of water hammer in these kind of 25 feedwater systems and eliminated the things that have caused O ANN RILEY &' ASSOCIATES, LTD.
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56 1 previous incidents of it. That's minimizing it, I guess.
() 2 DR. WALLIS: It's just extremely likely you will 3 have some water hammers, and what you've probably done is to 4 design them so that these will be so small that they won't 5 do any damage.
6 DR. CARROLL: Or you won't even know it's 7 happened.
8 DR. WALLIS: It won't do damage. Then you've got 9 to be specific about that.
10 MR. HUTCHINGS: Well, this last bullet, for -
11 example, gives a feature where we have this cross-connection 12 from our main feedwater system to our start-up, which is a 13 smaller line, okay, where we could have tried to run that 14 through our main-line, but we think that would give us more
() 15 probability of water hammer.
16 DR. CARROLL: Well, it's happened.
17 MR. HUTCHINGS: No, I'm not saying that 18 facetiously.
19 DR. CARROLL: It's happened in the real world.
20 MR. HUTCHINGS: So, in this plant, this is 21 different, okay? This is something we've done different to 22 --
23 DR. CARROLL: Is that the only thing you can think 24 of that you've done that would be -- that would -- I'll use 25 the word -- minimize water hammer?
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57 1 MR. WINTERS: This is Jim Winters again.
2 We did a number of things relatively to the 3 routing of the main feed lines.
4 One cause of water hammer is having long 5 horizontal runs with no slope. We do not have those. We 6 have a slope in all of our runs.
7 Another one is having -- where it comes to the 8 steam generator main feed ring connection, if you run your 9 main feed line high, have a goose-neck in it, and come back 10 down to the generator, then you tend to drain out that part I 11 through the feed ring and then you have a water hammer when 12 you refill.
13 Ours is horizontal. We do not have a goose-neck 14 in the top of that.
15 This cross-connection to where we don't put cold 16 feedwater into a big line is another one, and in fact, on 17 restart, not initial start but restart, that's a big one, to 18 make sure that we don't stick that cold water into a big 19 feed header.
20 We have used the information available, including 21 --
I don't have the exact reference either for this report 22 that you're talking about that the gentleman did for ASME.
23 There are guidelines in there. We have eliminated all of 24 the known source from those kind of guidelines.
25- Horizontal runs are kept to a -- there's a L over O ANN RILEY & ASSOCIATES, LTD.
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58 1 D ratio that you don't want to exceed. We're close to the. l
() 2 3
limit, but we're okay on those. Velocities, for certain temperature conditions, we've also designed around those. 1 1
4 We've done what we could based upon the known 5 effects of water hammer which were discovered not by i
6 analysis but discovered by experience. We don't know if 7 this particular layout that we have, that we worked very l 8 -hard to get rid of all the known causes of water hammer, 9 will have no water hammer. So, we have a test to try to 1
10 make it -- not try to make it hammer but to go through the 11 normal start-up and re-start procedures, and we expect it 12 not to hammer.
13 CHAIRMAN HARTON: And you used industry experience 14 you get from INPO, NRC, and others, put that back in the 15 design?
l 16 MR. WINTERS: INPO, yes. Our own standards, yes.
17 We were handed some guidelines by NRC which were -- we l
l 18 didn't get backed up by a report, so I can't tell you that 19 we -- I think we passed NRC guidelines, but there are no NRC 20 guidelines on the street other than --
21 CHAIRMAN BARTON: Reports of actual plant events 22 the NRC may have investigated and prepared various reports 1 i
23 on , in addition to what you're getting back through industry i 24 experience through INPO.
25 MR. WINTERS: Yes.
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59 1 CHAIRMAN BARTON: Okay.
l
() 2 MR. WINTERS: Recognize that those reports didn't 3 have definitive criteria, like you have to have more than 4 half-a-degree or you have to have more than 10 degrees on a 5 slope. It just said, gee, you shouldn't have a horizontal l 6 run.
[
l 7 CHAIRMAN BARTON: Okay. Thank you.
8 DR. CARROLL: Do you have J-tubes on the steam 9 generator feedwater headers or spargers?
10 MR. WILSON: Yes.
l 11 DR. CARROLL: That was a big source of water 12 hammer in the good old days before we had J-tubes.
l 13 MR. HUTCHINGS: We also have a start-up feedwater i 14 system, and basically, this also has some safety-related
() 15 functions of providing isolation, and the non-safety-related 16 functions, again, are in the turbine building. The next i
17 slide gives a little bit more information, actually, on that 18 system.
i l 19 Again, we can supply and we do supply the 20 feedwater through the start-up feedwater control valves to 21 the steam generators, either through the start-up pumps or 22 the main pumps, and the start-up feed pumps automatically 23 supply feedwater to the steam generator in the event of the i
24 main system going down for some reason, and I guess the 1 25 other thing is that this start-up feedwater system takes i
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1 water not from the deaerator storage tank but actually takes
( ) 2 it from the condensate.
3 So, it's a cold system, and the reason we do that 4 is, really, simplification of our cross-connects in our 5 design, and our main feedwater pumps are designed to take i 6 the plant all the way from full load down to zero power.
1 7 You don't have to cross over to the start-up system, 8 particularly when we're coming down.
! 9 DR. KRESS- What's the capacity of that start-up l
10 system with respect to the main feedwater system?
11 MR. HUTCHINGS: You mean percentage-wise?
12 DR. KRESS: Yes.
l 13 MR. HUTCHINGS: It's 5 or 10 percent. I can look i 14 the number up.
t ( '\
l 's ,/ 15 DR. KRESS: That's close enough.
16 DR. UHRIG: Isn't it more like 15, typically?
17 MR. WINTERS: We'll get you that number over 18 lunch. We'll get the answer over the lunch period.
l 19 MR. HUTCHINGS: Next we'll talk a little bit about 20 the main condenser.
21 Basically, this is a -- we have titanium tubes, l 22 which we picked as a standard for durability. It does do l
23 some level of deaerating down to 10 parts per billion of 24 oxygen.
25 DR. CARROLL: These are 22-gauge titanium if I O -/
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61 l' remember.right.
() 2 MR. HUTCHINGS: Yes, 20 or 22.
3 DR. CARROLL: Based on some personal experience, I 4' would admonish you to look at the spacing between tube 5 support plates, because those things are not very stiff.
6 MR. HUTCHINGS: All right.
7 DR.' CARROLL: You could end up with cracked 8 titanium very readily.
9 MR. HUTCHINGS: Okay.
10 The hot well is designed for three minutes of 11 storage at full load, and the condenser is designed to 12 handle up to 40 percent of a full by-pass flow at full load.
13 These other systems are just the support systems.
14 The condenser has two shells, two slightly different
() 15 operating pressures in the shells. We have one' vacuum pump 16 on each shell with a third vacuum pump as a back-up. We 17 have a steam by-pass system, which again, that is a system 18 that will by-pass 40 percent of the main steam to the 19 condenser.
20 DR. CARROLL: The vacuum pumps are for normal 21 operation? You don't have steam jet air ejectors?
22 MR. HUTCHINGS: Correct.
23 DR. CARROLL: And they also hog down the 24 condenser? !
25 MR. HUTCHINGS: Correct. I believe we might use 1
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l 62 1 that third pump to help during start-up.
() 2 The by-pass system is also designed to help take a 3 reactor trip from 100-percent power and take-a 100-percent
.i 4 load rejection or turbine trip from 100-percent power !
l 5 without a reactor trip.
l 6 DR. UHRIG: And 40 percent of the steam, then, l 7 by-passes the turbine and goe.c iato the condenser.
l 8 MR. HUTCHINGS: That's in an event where the 9 turbine trips off-line, yes.
10 DR. UHRIG: Okay.
- 11. MR. HUTCHINGS: It goes into the condenser and 12 then the rest goes to atmosphere.
13 DR. UHRIG: And this can be done without tripping 14 the reactor.
() 15 MR. HUTCHINGS: Correct. That's the design basis.
16 DR. UHRIG: The rods are programmed to go in, 17 MR. HUTCHINGS: Right.
18 DR. UHRIG: Thank you.
19 MR. HUTCHINGS: Then our circulating water system 20 -- on AP600, we have a generic design, but it's -- but the 21 system is actually a site-specific design. Only the 22 condenser is really standard in the plant. We have a 23 cooling tower on our generic design, and we have two i
24 circulating water pumps, two 50-percent circulating water 25 pumps, but if you remember the slide that showed the i 1
t
~
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63 1 ' coincident wet bulb temperature, that's where we picked as
() 2 the starting point for this, but the COL applicant would 3 actually submit what the final circ water system design 4 looks like and whether or not it even has a cooling tower in 5 it.
6 DR. CARROLL: Oh, okay.
7 MR. HUTCHINGS: Okay?
8 DR. UHRIG: You can have it without a cooling 9 tower.
10 MR. HUTCHINGS: You can have it without a cooling 11 tower.
12 CHAIRMAN BARTON: If you think you can get it 13 approved environmentally.
14 DR. SEALE: You may have either a forced draft or
) 15 a natural draft cooling tower.
16 MR. HUTCHINGS: Right. The only thing we do have 17 a cooling tower for in our standard design that we'believe 11 8 would be maintained is in our service water system. That's 19 a separate little cooling tower,. independent of the main 20 tower. ,
1 21 CHAIRMAN BARTON: Mechanical tower.
l 22 MR. HUTCHINGS: Yes.
23 This just touches upon the fact that we have a i
l 24 steam generator blow-down system. l 25 Probably the most unique thing here -- and'I'm not l
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(
64 1 an expert in this by any means -- is we use these
< rg i
( j 2- electro-deionization mineralizing units to remove
! 3 impurities. I think it's some sort of charge to the plates 1
4 that pull the ions off.
5 We have a condensate polishing system.
l 6 CHAIRMAN BARTON: Could you answer a question 7 about the polishing system?
8 MR. HUTCHINGS: I'll try.
9 CHAIRMAN BARTON: How many condensate polishers do 10 you have? I was reading, I think, in some places, where 11 you've got one; some places, I think, there's two. Can you 12 please straighten that out in my mind? How many polishers 13 are there?
L 14 DR. POWERS: I thought it was three at one place.
l' 15 CHAIRMAN BARTON: I believe three also.
16 MR. HUTCHINGS: I can check, but I think the way 17 it works, what some of the confusion is, is the system is i
18 designed to do this one-third of full flow, okay, given a 19 level of water quality that is defined. Then we expect 20 there is going to be some sites where the water is a lot 21 worse, okay, and what you can do is -- there is space
- 22 available to add -- I think there's one system now, and I 23 believe you can put a total of up to three in order to clean 24 up the water.
l 25 CHAIRMAN BARTON: The standard, you're telling me, l
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65 1- is one which allows for one-third of full flow to be
() 2 polished all the time.
3 MR. HUTCHINGS: No. Well, all the time. That 4 system is not normally on-line. It's used during start-ups 5 or pre-start-ups or if you need to clean up water because 6 your chemistry is out of control, but normally it is not 7 operable.
8 CHAIRMAN BARTON: So, you do not have constant 9 condensate polishing.
10 MR. HUTCHINGS: Correct. It's only when the 11 chemistry requirements need it.
12 CHAIRMAN BARTON: Is that realistic? Are plants 13 like that running today that don't have any condensate i 24 polishing?
15 MR HUTCHINGS: Yes.
16 DR. CARROLL: Well, a lot of PWRs started life 17 without them. A lot of them --
18 CHAIRMAN BARTON: -- have added it. That's why I 19 just wondered whether it's really realistic to assume that 20 you can run it without any condensate polishing. l l 21 DR. CARROLL: Well, I think they're counting on i
22 those titanium tubes. Make sure you don't crack them. It's 23 easy to do.
24 The place people get in trouble on those, by the 25 way, is more rigid copper alloy tubes have a certain spacing O ANN RILEY & ASSOCIATES, LTD.
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66 1 between support plates.
~~() 2 MR. HUTCHINGS: Right. I 3 DR. CARROLL: And'if you re-tube a condenser with
.4 titanium --
5 MR. RUTCHINGS: -- you better move fast.
6 DR. SEALE: You have to re-tune them, just like a 7 piano.
8 CHAIRMAN BARTON: I'm sorry I got you off on this, 9 but I think I understand what your design is.
10 MR. HUTCHINGS: Okay.
11 And then we have a -- what we call a turbine 12 island chemical feed system. It's a central location for l 13 providing chemicals to various sub-systems -- the
, 14 condensate, feedwater, circ water -- as needed, and all of i
,,~
(,) 15 that's located in the turbine building.
16 And then this is just a general statement, but we ,
l 17 believe that, based on our design and the review from the
! 18 -staff, that what we've provided is adequate to support the 19 design certification.
20 DR. CARROLL: I'm looking at table 10.3.5-1, sheet 21 3 of 3, guidelines for secondary side water chemistry during 22 power operation, and I've kind of lost track of all this l
23 good stuff, but I thought the current EPRI guidelines on I 24 this emphasized molar ratios. These do not seem to do that.
25 MR. HUTCHINGS: I don't know specifically -- I do l
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e 67 1 know that that is in accordance with the URD requirements.
() 2- I don't know specifically --
3 DR. CARROLL: Okay. Because you can -- that's 4 interesting, also. You can have some of these parameters 5 well within the limits, but if the molar ratios are wrong, 6 you can end up with -- in crevices, where you get alternate 7 heating -- or alternate wetting and drying, you can have 8 very aggressive concentrations. Okay.
9 But you're telling me this is the URD numbers.
10 MR. HUTCHINGS: Yes.
11 DR. CARROLL: Okay.
12 CHAIRMAN BARTON: Any other questions?
13 DR. UHRIG: I've got a couple, just for 14 information, primarily.
() 15- Going back to the turbine trip, protective trips, 16 it lists a number of things that create protective trips, 17 one of them being high condenser back pressure. How high 18 does that have_to get before it trips the turbine?
19 DR. CARROLL: Probably five inches.
20 MR. HUTCHINGS: I was going to say six.
21 DR. UHRIG: Five or six? Is this just -- the 22 reason is, I guess, it has nothing to do with the loss of 23 efficiency, it has to do with some --
24 MR. HUTCHINGS: -- protection of equipment.
25 DR. UHRIG: Just protection of equipment. Okay.
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68 1 DR. CARROLL: Yes. If the vacuum's going to hell
() 2- on you, next thing you're going to do is blow the rupture 3 disks. Okay.
4 .MR. HUTCHINGS: And you don't want to damage the 5 blades or anything.
6 DR. UHRIG: The other thing is thrust bearing wear 7 -- is this a vibration issue? Do you have a vibration 8 sensor that you put in there? How do you detect that? Is
, 9 there any warning on this, or is it just suddenly trip and l
l l 10 tells you it was a --
11 DR. CARROLL: Usually there's an alarm and then a t
! 12 trip.
1 13 CHAIRMAN BARTON: That's the typical design.
l 14 DR. CARROLL: It's usually a --
() 15 DR. UHRIG: -- variable transformer.
16 DR. CARROLL: Yes.
l 17 DR. UHRIG: Okay. Thank you.
l l 18 CHAIRMAN BARTON: Does staff have any comments on 19 Chapter 10?
l 20 MR. LYONS: This is Jim Lyons. I'm the Section l 21 Chief with Plant Systems Branch, responsible for most of the l
l 22 sections in this chapter.
l 23 I guess I wanted to address one comment, I guess, !
i i
24 that was made before about how you all take confidence in '
25 the staff's review.
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l
I 69 1 We review the systems that were here, that we
() 2 _ discussed here, plus -- and all the systems in the plant --
3 to the Standard Review Plan that gives us guidance on what 4 are the issues we want to address for each one of the i 5 systems, what are the applicable codes and standards, and it l 6 gives one acceptable way for the system to meet the l
l 7 Commission's rules and regulations.
8 A licensee can always propose to do that -- to 9 meet the rules and regulations in another way, and we'll l 10 review that on a case-by-case basis. So, we have a very i
11 structured way that we go through to do our reviews.
12 And then the Standard Review Plan, which, for the 13 most part, was written in the late '70s, early '80s -- we 14 supplement that with the operating experience and the
() 15 resolution to generic issues that have gone on since then, 16 and so, we pick up any new knowledge that we have up to the 17 time that the application is submitted, and we also review 18 those issues to make sure they're addressed properly, and in l 19 this case, we've completed our review of Chapter 10.
20 The draft FSER that you received, at the time we I l 21 had written it, hadn't -- we hadn't had the benefit of 22 receiving rev 21 to the SSAR.
23 We've now verified that our FSER is consistent 24 with the SSAR.
25 DR. CARROLL: So, what is your thoughts on boring l
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r 70 1 high-pressure turbine rotors and generator rotors?
() 2 MR. LYONS: That's not one of the areas that my 3 group is reviewing. Really, the Mechanical Engineering 4 Branch does the review of the turbines and the -- and I was
- 5. just thinking, when you brought that up before, gosh, it's 6 been five, six years.
7 Both Westinghouse -- I guess maybe even longer 8 than that. We were -- when we were reviewing the Utility 9 Requirements Documents --
10 DR. CARROLL: Right.
11 MR. LYONS: -- both Westinghouse and General 12 Electric and I think -- and Combustion Engineering all came 13 in and gave us a real good presentation about turbines and, 14 you know, where they were going with these and wny they were
() 15 doing certain things, and I remember going to it and being 16 very interested, but I certainly don't remember any of the 17 details.
18 DR. CARROLL: But they changed their mind at that 19 time in terms of at least boring low-pressure rotors. At 20 that time, they were saying they weren't going to bore 21 anything.
22 I guess everybody understands why boring is 23 important. There are two reasons. One is that impurities 24 tend to migrate, and then other is, once you bore it, you 25 can much more easily go in with non-destructive testing and i .
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71 1 see if the area beyond the bores is in good shape,
()
t
- 2 CHAIRMAN BARTON: At this point, we'll take a 3' break at reconvene at 25 of 11.
4 DR. WALLIS: You remember we asked about 5 minimizing water hammer? Is the staff satisfied that 6 Westinghouse has minimized water' hammer?
7 MR. LYONS: Yes, we've done a review, and in fact, 8 the report that Dr. Catton talked about -- we took -- we had 9 asked them how they addressed the issues in that. That's 10 what Mr. Winters was talking about when he said that they 11 addressed this issue.
12 DR. WALLIS: This MIT report from Peter Griffith's i 13 student? Is that it?
14 MR. LYONS: Yes, but we didn't actually give them
( 15 the report. If I remember right, there was --
16 DR. CATTON: I think it was something subsequent I 17 to that. Peter actually did a study for the research group 18 here.
l 19 MR. LYONS: Jin Guo of my staff is the one who did 20 the review.
21 MR. GUO: I'm the one that reviewed the water 22 hammer and the other stuff. I reviewed this based on the 23 SRP, the Branch Technical Position 10-2, particularly for l 24 water hammer problem. I
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72 1 item. We compared what the design -- for example, they used
() 2 3
.for figuring upward instead of downward.
gravitational. velocity caused water hammer.
This can reduce This is a good 4 design. So, we found out the design is good.
5 I also used an MIT paper. The diameter ratio 6 should be less than 20-something, and the length of the pipe 7 should be as short as possible and the slope of the pipe as 8 flat as possible.
l 9 So, we reviewed all the cases. I believe we wrote l
10 many letters on water hammer, at least six or seven letters, 11 to meet all the requirements.
12 Of course, we know that water hanmer is a fluid 13 mechanics problem. So, you cannot say there is no water 14 hammer.
15 So, we also required a test. For the test, we've
- 16. been arguing for a long time, because they said, based on 17 the operation, they found out there was no water hammer. I 18- said no, we should test, because this is a new plant, this 19 is a new idea, different from operating plant. So, they do 20 perform the test.
21 So, therefore, I believe the water hammer problem 22 is not meaningful in the AP600 design.
23 DR. WALLIS: Did you get a bounding estimate of 24 the loads from these possible water hammers which you say 25 couldn't be -- you couldn't reduce the probability to zero, l
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73 1 but you could perhaps bound the loads.
() 2 3
MR. GUO:
DR. WALLIS:
Yes.
You did that.
4 MR. GUO: I did that.
5 DR. CATTON: How did you calculate the loads?
6 MR. GUO: The loads we cannot calculate.
7 DR. CATTON: That's what I thought.
8 So, he didn't.
9 MR. GUO: See, water hammer is a hydraulic 10 problem. So, you have to know the velocity of the pipe, the 11 water, the pipe size, length of the pipe, how it is sloped, 12 and the time.
13 If you turn off the water more than one minute, 14 then you get no water hammer. If you turn off the water in
() 15' two seconds, it becomes a water hammer. So, there are many 16 phenomena that cause the water hammer.
17 We're trying to minimize the water haLaer to close 18 to zero, That's what we can do. We cannot eliminate water 19 ' hammer, that's for sure.
20 DR. CATTON: And the problem is, if they calculate 21 the bounding load, it's_ god-awful.
22 DR. WALLIS: Yes, it's intolerable, usually.
23 MR. GUO: The bounding condition is the design.
24 For exauple, the diameter ratio with the pipe length --
25 those are the bounding numbers. Velocity requirement and ANN RILEY & ASSOCIATES, LTD.
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l 74 l
l 1 -the_ slope requirement -- l i
() 2 DR. WALLIS: Well, I'm sure that this design is 3 very much better than it would have been if you and-4 Westinghouse hadn't done what you've done.
I 5 I think, though, there's still a question of how 6 good it is, because there seem to be uncertainties about l 7 this phenomenon, and maybe this indicates that the agency 8 should keep doing research on it or something like that, 9 because it's not as if we really understand it and can 10 really be sure it will never happen, and if it does happen, 11 we can't really be sure what the loads will be. Is that 12 right?
13 MR. GUO: Right.
14 CHAIRMAN BARTON: All right.
, ) 15 DR. CARROLL: I do take some comfort from the fact l 16 that they are going to actually test it during start-up.
17- DR. CATTON: There's a long history to this water 18 hammer.
19 It was declared a resolved issue, and from that 20 point on, nobody really looked at it very much, and this 21 committee has been on the opposite side of that, feeling 22 that they ought to do something about it and try to bound 23 these kinds of loads, but it's never happened.
24 CHAIRMAN BARTON: We'll go back on break till 20 25 of 11.
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75 1 [ Recess.]
m (s ) 2 CHAIRMAN BARTON: We'll come back in session.
t 3 The next agenda item is Chapter 12, radiation 4 protection. I 5 Jim Winters?
6 MR. WINTERS: Yes.
7 Good morning again.
8 I'm going to talk about Chapter 12. It's got a 9 fancy title of radiation protection, but really, all we're 10 going to talk about is shielding. The other part of 11 radiation protection, which is offset releases, is covered 12 in Chapter 11 relative to liquid and gas waste.
13 What I'd like to do is quickly go over the basis, f 14 what philosophical features we went through during the rx y ) 15 design of AP600 to do the best job we could on radiation 16 protection from a shielding point of view, talk about the 17 results, and come to a conclusion.
18 DR. POWERS: Will you be talking about crud 19 accumulations and things like that?
20 MR. WINTERS: Yes, I can. I don't have a prepared 21 slide, but we have done things to minimize crud accumulation 22 or to minimize the effects of crud accumulation.
23 DR. POWERS: Good. l l
24 DR. CARROLL: And you know what " minimize" means.
25 CHAIRMAN BARTON: " Reduce" will get you in less
' \
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76 1 trouble.
2, MR. WINTERS: We, for example, reduced the use of 3 '- cobalt alloys to the minimum extent possible and so forth.
4 DR. SEALE: Will you tell us about things you've 5 done~to condition surfaces so you have less accumulation and 6 adherence to those surfaces,. easier to keep them clean and 7 avoid the -- surrendering areas of the plant to the mercies 8 of contamination tape.
9 MR. WINTERS: Yes, in that we're using coatings on i 10 all the surfaces, epoxy-type coatings.
11- DR. SEALE: And using materials that are easy to 12 clean.
13 MR. WINTERS: Right.
, 14 Our bases were to have a high consideration for 1 15 ALARA, of course.
( 16 DR. WALLIS: ALARA meaning?
17 MR. WINTERS: As low as reasonably achievable.
l 18 DR. WALLIS: That's another one of those l 19 meaningless statements.
20 DR. POWERS: That one has a lot of meaning.
21 DR. SEALE: -It's like a cult, almost. It has a 22 status that is overwhelming.
l l 23 DR. POWERS: ALARA is used in this context even as l
! 24 a defined limit on $2,000 per man rem avoided.
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77 1 measure.
() 2 3
DR. POWERS:
DR. WALLIS:
Yes, it does.
When it's just seen by itself, it 4 looks like one of those other meaningless statements.
5 DR. POWERS: It has a firm and revered history.
6 MR. WINTERS: For full-power operation sources, 7 which'are all the radiation sources, which in our case is 8 mostly water and what's carried by water, we include a 1
9- quarter-percent failed fuel for shielding design.
10 When you get to listen to rad waste, Chapter 11, l 11 you'll see that we used the .1-percent -- I mean, excuse me i
12 -- the 1-percent failed fuel for off-site and for actually j 13 handling the water, but for shielding, it's a 14 quarter-percent.
() 15 DR. WALLIS: What does " failed" mean? Does it 16 mean that that amount is dispersed in the water, all of that 17 fuel somehow is crumbled and put in the water, or what?
18 MR. WINTERS: No. It means that one-quarter of 19 the rods have a defect to the extent that they are now
- 20. leaching, and there is a defined source term for that.
21 DR. WALLIS: So, there is a source term.
22 MR. WINTERS: Yes. j 23 DR. WALLIS: It doesn't mean that everything comes 24 out good.
i l 25 DR. POWERS: What I don't understand is why the 1 1
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f- i l
l l 78 l 1 differential between the 1 percent for you off-site releases
'() 2 and the quarter percent for your shielding.
3 MR. WINTERS: We have a history with Westinghouse
- 4 fuel.
1 5 DR. POWERS: I understand the history situation, 6 but it's the discordance in the analysis.
7 MR.- WINTERS: Because we started with a quarter 8 percent for everything, did our analysis past, realized that
! 9 we weren't going to make it against SRP on the handling 10 systems, the rad waste systems, and so then did a back 11 calculation to see if they were still good for 1 percent.
12 They were, so we're okay. '
13 DR. POWERS: Okay. So, it is really the -- the 14 situation is you consistently went through and did a quarter l[
- 15 percent --
16 MR. WINTERS: Right.
17 DR. POWERS: -- and then, because of the SRP.for 18 those off-site sources, you did a 1-percent.
19 MR. WINTERS: Right.
1 20 DR. POWERS: Okay. Just so that the thought isn't 21 lost, the failed fuel rate is somewhat less than .1 percent.
22 MR. WINTERS: Right. And we can detect even below
]
23 that. I mean 1 percent is where some people actually allow 24 themselves to run, but we can detect failed fuel well below 25 than and then do something about it if you feel like it.
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79 1 DR. POWERS: Is that going to be true when they go
() 2 to higher-burn-up fuel?
j 3 UR WINTERS: Yes.
t 4 DR. POWERS: How do we know that?
l 5 MR. WINTERS: Because the requirements for fuel 6 integrity are the same, even though you've got more burn-up.
7 DR. POWERS: It's going to be a limiting factor to 8 consider in how far we go in burn-up.
9 MR. WINTERS: Right.
10 For sources away from the reactor coolant system 11 -- that is, for the CVS system which cleans up reactor 12 coolant, the purification system, for sampling, for places i
13 where water or radioactive water will tend to want to go '
14 away from the reactor coolant system during normal I ) 15 operations, conservative time estimates were assumed there.
16 In most cases, those conservative time estimates was that 17 there is no time between when it left the reactor coolant 18 system itself and ended up in the ion exchanger or in the 19 valve that had to be operated to get the CVS going or 20 whatever. That's what conservative time estimates --
21 DR. POWERS: And that really just affects the 22 decay rate?
23 MR. WINTERS: It affects the decay rate. So, you 24 have a much higher source in your analysis than would be in 25 reality, because you assume no time, that it just is -- the ANN RILEY & ASSOCIATES, LTD.
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80 1 N16 hasn't decayed, none of your crud and corrosion products
() '2 have decayed.
3 Similarly, for rad waste sources, when v -- the 4 rad waste systems as input, they use conservative time.
5 estimates of the same nature.
~
6 For accident sources, which is a different set of i
7 calculations, we use an un-modified NUREG-1465. The reason 8 that's important today is because, the last time we were 9 here_ talking to you, we had a modified NUREG-1465.
We were 10 using 1465 with some -- what we thought were minor 11 differences, and obviously, they were too much. So, .now i
l 12 we've redone the analysis for unmodified NUREG-1465 as a 1
13 source for accident sources.
14 DR. SEALE: Just to remind myself of what those
) 15 differences were --
16 MR. WINTERS: Oh, boy.
l 17 DR. SEALE: -- just in a very rough way, you do j 18 have a time-dependent release.
19 MR. WINTERS: Yes.
20 DR. SEALE: But the release fractions on certain 21 isotopes are now back to the original 1465 numbers and not
- 22 in a modified --
l l
23 MR. WINTERS: Yes.
i L 24 DR. SEALE: Okay. But the time-dependent release 25 is still in there.
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81 1 MR. WINTERS: Yes.
2 DR. SEALE: Okay. That was what I wanted to l
3 remind myself of.
4 DR. CARROLL: Why the conservative time estimates?
l 5 Is that something the staff ~ required you to do, or is it 6 something.you think is an appropriate conservatism?
! 7 MR. WINTERS: It's an appropriate conservatism, 8 but really it's just easier to do. It takes one step out of 9 the calculation, and because we have a robust shielding 10 design, because there's a lot of concrete where we have it 11 in this plant, we didn't need to not use that conservative 12 assumption.
13 DR. CARROLL: Okay.
l 14 MR. WINTERS: Okay.
15 The required design features necessary to maintain l
l 16 shielding are delineated in the SSAR. Most of those are i i 17 concrete thicknesses, which are -- we use minimum concrete l
18 thicknesses for shielding, and usually structural 19 considerations require more concrete than.what's required
, 20 for shielding.
l l
21 In some areas in the fuel handling area, however, 22 shielding thicknesses take over, and those are delineated in 23 the SSAR.
24 DR. POWERS: Do you specify your aggregate in your 25 concrete?
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i 82 1 MR. WINTERS: The whole concrete thickness is
) 2 specified and whether it's shaken -- the answer to your j 3 question is yes, but there's more to it than just aggregate.
4 DR. POWERS: I guess what I'm asking you is do you 5 have shielding-type aggregates or do you just make a 6 concrete quality specification?
7 MR. WINTERS: It's concrete quality. It's not 8 shielding. It's regular structural concrete, and we don't 9 take extra credit for modifying it.
10 DR. UHRIG: And you don't use heavy aggregate or 11 anything.
12 MR. WINTERS: Not for the purposes of shielding, 13 no.
14 DR. CARROLL: But it is vibrated so there's no
() 15 voids?
16 MR. WINTERS: Yes. Well, it depends on where 17 we're talking. Inside containment, in the modules, when you 18 guys discuss the structural features of the plant, where we 19 have these sandwich arrangements, it's vibrated and tamped 20 as they fill up the modules.
21 I put a few bullets here that was our design 22 philosophy. I left an important one -- two important ones 23 off, and so we'll talk about those first.
24 One thing that was good about AP600 is, in 25 general, we could start with a clean sheet of paper, and
/)
\m/
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83 1 we'll talk about that again tomorrow when we talk about some
() 2 of the auxiliary systems, especially HVAC and fire 3 protection, as well, so that we could take general 4 approaches here that an evolutionary plant couldn't because 5 they were coming from a known layout. We had the 6 opportunity to start with a layout that didn't exist before 7 and force some things on our design. ,
8 One of those things we forced was to segregate 9 radiation sources. We clearly defined what was going to be 10 the dirty part of our plant -- radiation-wise dirty -- and 11 the clean part of our plant and made sure that we had no 12 access except through defined paths, we had concrete walls 13 so people just couldn't wander into these places, and it was 14 easy for us to establish access control, because we designed
() 15 access control into it.
16 DR. CARROLL: You're talking here about radiation 17 as contrasted to contamination.
18 MR. WINTERS: Yes.
19 Now, as far as support systems go, then you have 20 to make sure that your HVAC, your drains, all of those types 21 of support systems which may connect potentially 22 contaminated areas or areas with radioactive sources from L 23 areas that shouldn't have those, and we forced ourselves to 24 promote that by designing the support systems HVAC and 25 drains to always move whatever, whether it's air or drain ANN RILEY & ASSOCIATES, LTD.
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84 1 water, from clean areas towards dirty areas or potentially
( ) 2 dirty areas.
3 DR. CARROLL: Okay.
4 MR. WINTERS: Similarly, on accident scenarios, 5 AP600 requires little operator actions after an accident.
6 That's one of the beauties of it. And this is not to imply 7 that we designed in automatic. We designed out operator 8 actions. Operator actions are not required. It's not 9 because automatic actions are required. It's because no 10 action's required.
11 So, we minimize the number of things that an 12 operator would have to do after an accident that would 13 expose him co a radiation field.
14 There are some, depending upon the accident, some 15 more than others, but they're in the handful rather than in 16 the tens or twenties of actions. There are a couple of 17 manual valves that we have to open on certain accident 18 scenarios. Those valves are in a protected area, but it is 19 a higher radiation than normal.
20 We also -- I'm sorry.
21 DR. CARROLL: I was going to ask about radioactive 22 drain lines. Do these have water traps in them?
l 23 MR. WINTERS: Yes.
24 DR. CARROLL: And that is a crud trap, also. j 25 MR. WINTERS: It is a crud trap, also.
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9
85 1 DR. CARROLL: How do you keep them full? If it's (O) 2 important that you have that seal, they're going to 3 evaporate away unless you have some mechanism for adding 4 water.
5 MR. WINTERS: We'll have to look into that. I 6 don't have an answer for that right here.
7 DR. CARROLL: It's an old question.
8 MR. WINTERS: It's an old question.
9 DR. CARROLL: An old problem. It has caused grief 10 in some places.
11 MR. WINTERS: Right.
12 Relative to contamination and crud inside primary 13 systems, we reduced the amount of cobalt used in alloys to 14 the least we can get by with.
(-
(_) 15 The only place we have it now are some of the 16 surfaces in the main coolant pumps, recognizing that we have 17 fluid bearings in the main coolant pumps, but there is a 18 very little bit of cobalt. I think we reduced that by --
19 I'm not quite sure, but by 70 percent from normal plants or 20 other plants.
21 For decontamination, we specify epoxy coatings on 22 all surfaces that could be potentially contaminated except )
23 those that are already stainless steel, and we have a lot of 24 stainless steel surfaces in containment on some of the 1 25 surfaces simply because we plan to put water in them anyway.
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1 l
86 1 The IRWST, the refueling canal already have stainless steel
() 2 walls.
3 Most of --
4 DR. CARROLL: Back to cobalt elimination, your 5 table says you're going to use low- or no-cobalt materials.
6 What's available today in terms of a hard-facing material E 7 that.isn't stellate?
l 8- MR. WINTERS: We'll have to ask. I believe that 9 we use a lot of nitrating surfaces.
10 DR. CARROLL: Nitrating.
11 MR. WINTERS: But we need to check, because I'm 12 not an expert in that particular case. But I do know that, 13 in some areas -- like on the CRDMs, we use nitrated surfaces 1
14 as opposed to stellate surfaces. But in the main coolant
() 15 pump, we're going to have to check. We'll get back to you 16 after lunch on that one.
17 DR. CARROLL: Okay.
18 MR. WINTERS: I don't know.
19 Okay.
20 Just to give everybody --
21 CHAIRMAN BARTON: You don't design the whole 22 process that would allow -- I guess you do. I'r trying to 23 think of anything that's left to the licensee to design that 24 could bring cobalt-bearing materials in. I guess that's all 25 under Westinghouse, isn't it?
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87 1 MR. WINTERS: Yes.
() 2 3 up.
CHAIRMAN BARTON: The licensee can't screw this 4 MR. WINTERS: No.
5 CHAIRMAN BARTON: Okay.
6 MR. WINTERS: Once it leaves what we have in the 7 rad waste situation, he can screw it up in his mobile 8 processing or in his off-site -- as he takes it away from l
9 the plant, if he puts it the wrong kind of a cask or --
10 CHAIRMAN BARTON: But ve.can't do it so it gets 11 into the core.
12 MR. W1NTERS: No.
13 C5 AIRMAN BARTON: Okay.
14 MR. WINTERS: We're going to talk a lot in the
() 15 next couple days about how this site is arranged and some of 16 its features on arrangements, so I wanted to start from the 17 site in.
18 Our plant north is that way, which is just as 19 arbitrary as our plant elevation of 100, but that's what we 20 call north. Here is our shield building, reactor 21 containment, surrounded by what we call the auxiliary 22 building, the rad waste building on one side. The annex 23 building is the general office and personnel building and 1
24 the turbine hall. !
25 What I've outlined here is the dirty end of the 1
l h
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88 1 plant. There are walls, floors, and access points that l
() 2 determine that -- so there's no migration of potentially i
3 radioactive materials across this boundary.
4 The fuel handling area is in this part of the aux l 5 building. All of the primary coolant processing, liquid rad 6 waste, gaseous rad waste is in this area. In the annex, we 7 have the health physics labs. The rad chem lab is here, the 8 hot machine shop is here, and access to containment is 9 through this corridor.
10 Then on the clean side, here's the normal access 11 to the plant, lockers, offices, security, main control room, 12 and all of the safety-related I&C and electrical gear are in 13 this end of the plant.
l 14 The other thing we did which you should be hearing
() 15 over and over is that all safety-related equipment is on the 16 nuclear island, which is defined by the auxiliary building 17 and the reactor containment building and the shield 18 building.
19 There is no safety-related equipment outside this 20 boundary, that nuclear island. The rest of it may contain ,
i l 21 radioactive materials, but it's not --
l 22 DR. SEALE: Could you generally just show us where 1
23 the security boundary is?
24 MR. WINTERS: What we consider to be the security t
l 25 boundary for the plant is -- this is the fence line, and it
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89 1 runs around here.
() 2 DR. SEALE: So, everything is inside that security 3 line.
4 MR. WINTERS: Yes. There are internal security 5 boundaries which we're not going to talk about this 6 presentation --
7 DR. SEALE: Okay.
8 MR. WINTERS: -- inside the plant, but the main 9 security boundaries outside the vehicle barriers are over 10 here.
11 With respect to the nuclear island itself, to give 1
12 you a closer view, I guess you can still see the line here.
13 At this elevation, this elevation is two decks below plant 14 grade, so it's next to bottom in the aux building. The most
) 15 northern aux building room that's potentially radioactive is 16 the CVS make-up pump room, and that's only because there are l 17 some recirculation-type lines in there.
18 Inside containment, the actual purification for l
19 CVS for reactor coolant, and the ion exchangers, are 20 actually inside containment, so that we don't need to take 21 hot radioactive coolant outside during normal operations.
22 The only real reason to take it outside is for sampling and 23 during let-down on the heat-up, because there's not enough 24 storage capacity inside containment. So, on a heat-up, we 25 would take reactor coolant outside of containment, s
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90 1 Now, again, on this side of the line, you notice
() 2 you have to leave this area, go outside, through a security 3 boundary to get back into the hot side. This is the
)
4 safety-related electrical and I&C gear.
'5 In the SSAR, there'are.three sets of radiation 6 maps based on these types of pictures, one for normal 7 operation, one for post-accident.
8 DR. CARROLL: Why am I not seeing the 9 in-containment refueling water storage tank?
10 MR. WINTERS: Because I'm too low. You're below 11 it.
12 CHAIRMAN BARTON: You're below grade here.
13 MR. WINTERS: Below grade.
14 Now, if I go up a deck,_on the next page, you'll
() 15 see it. This is the in-containment refueling water storage 16 tank.
17 DR. CARROLL: Okay.
18 MR. WINTERS: Okay?
19 DR. CARROLL: All right.
20 MR. WINTERS: We were below the bottom of that on 21 the last picture.
22 DR. CARROLL: Got you.
l 23 MR. WINTERS: This is the refueling cavity.
24 DR. CARROLL: Those things sticking out are the l 25 spargers.
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91 1 MR. WINTERS: No , sir. These things sticking out j 2 are reinforcements for that wall --
1 3 DR. CARROLL: Oh, okay.
4 MR. WINTERS: -- which is the water retaining 5 wall. One sparger sits here where my finger is and the next 6 sparger sits over here. They're not shown on this picture.
7 DR. CARROLL: You're right. You're right. 3 8 MR. WINTERS: What this is intended to show is how 9 we have broken up our HVAC systems.
I l
10 We have eight HVAC systems in this plant, so that i l
11 we can control where radioactivity goes, where fuel goes, 12 and ensure that we are cooling or handling air in places 13 where people are separate from where potential radioactivity 14 is.
l 15 In general, the pressures are set up so that
[
l 16 systems sense their neighbors and tend to have the highest i 17 pressure where people are moving towards where it's more 1
! 18 potentially contaminated.
l 19 The plant vent runs up the wall here. You can't '
l l 20 see it on this picture, but it runs up outside containment.
l 21 It's run by the VFS, which is the containment supply and l
22 purge system, and anytime one of these potentially I l
I 23 radioactive systems senses radioactivity, it discharges that i
24 to the filtered exhaust of the plant vent, which downstream J 25 of the filters, if that gets too high, then that turns ANN RILEY & ASSOCIATES, LTD.
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92 1- itself off.
() 2 3
DR. CARROLL:
exhausted to?
But normally, where are they being
-4 MR. WINTERS: Just out the stack.
5 DR. . CARROLL: Rooftop?
6 MR. WINTERS: Yes.
7 DR. CARROLL: Okay.
8 MR. WINTERS: These are normally exhausted out 9 their own exhaust plenums unless they sense high 10 radioactivity.
'll DR. CARROLL: And what does "high" mean?
12 MR. WINTERS: I don't know. If you mean in actual 13 counts per minute or something, I don't know, but it's well 14- below the limit. I know we have to have the 10 DAC and 15 those kind of requirements on the monitors in the radiation i I 16 --
17 DR. CARROLL: So, this is airborne radioactivity?
18 MR. WINTERS: Airborne radioactivity is what we're 19 talking about.
l 20 DR. CARROLL: All right.
l 21 MR. WINTERS: And you'll notice that the -- again, 22 they are separated by zones and they are separated by what L 23 they service.
I 24 For example, there are two subsystems in VAS, l l
i 25' which is our radioactive auxiliary building system, one that I
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93 1 covers the fuel areas and one that covers the fluid handling
() 2 areas.
3 VHS is for the hot machine shop and the health 4 physics area.
5 VXS is clean.
6 Now, you'll notice that, on the deck below this, 7 this was a dirty space, which was the CVS space. On this 8 deck, it's a clean space, so the boundary is moved over once 9 from clean to dirty.
10 So, VXS is clean, VBS is clean, and the VTS, which 11 is the turbine hall, is clean.
12 On the drain side, we separated the drains -- this 13 figure is in the SSAR, and I apologize, it's hard to read ,
14 here, but inside containment, all drains go to the sump,
() 15 then they can be pumped out to be processed by liquid rad 16 waste.
17 Outside containment, the drains are separated, ;
18 clean and dirty. There are clean drains in the aux building 19 and there are dirty drains in the aux building, but they are 20 separated by design to go to the correct sump so that they 21 can be handled properly.
22 Most drains in the aux building to the aux 23 building sumps, radioactive drain sump, although some of 24 them can go directly to the liquid rad waste monitor tanks.
25 From a results point of view, this is a simplified ANN RILEY & ASSOCIATES, LTD.
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l l
94 l
1 set of results in the three areas that are of importance.
() 2 .There are more results in the SSAR. In fact, there are many 3 tables and a lot of description of the zones.
4 From a shielding point of view, there is 5 negligible direct radiation at the plant site boundary, and 6 that means at the fence that we just talked about. That 7 doesn't mean a half-mile away, although a half-mile is not 8 very.far, but that's at the fence boundary.
9 DR. CARROLL: Protected area fence.
10 MR. WINTERS: Right.
11 This is the table of operational doses and the 12 percentage of totals that build up to those, which is well 13 below the established norms and requirements.
14 DR. POWERS: I guess I -- I mean I understand the 15 column labeled " percent."
16 MR. WINTERS.: Now, this is -- I think that's 17 person rem annual.
18 DR. SEALE: So, this is the number that you would 19 put into that performance indicator table for this 20 particular plant in the INPO performance indicator numbers 21 or whatever --
22 MR. WINTERS: Right.
23' DR. SEALE: -- which is currently somewhere around 24 90 something.
25 MR. WINTERS: Right. This one is -- the last I l
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95
. 1 remember was -- for an average was like 120. We're not l
() 2 quite hali of that. But now everybody else has gotten down
! 3 in the 90 range.
4 DR. SEALE: The year 2000 goal, I think, was l 5 around 95 or something. k 6 DR. POWERS: I guess the question that comes to 7 mind -- this is not a very big change from 120. It's not a 8 very big change from 90 even, and this is a plant that
)
9 exists only on paper. My question is if reality -- how 10 close to these numbers do we think we'd actually achieve?
11 MR. WINTERS: My belief is that, because of the 12 source terms and the conservatism we put into the analysis 13 of what a hot sample and what a hot piece of gear is when l
14 you do the maintenance, that we should come in well less 15 than this, in the 40 to 50 range.
16 Now, can we show that? Don't know. What's the 17 probability? Don't know. This is the annual estimated dose 18 based upon those conservative assumptions I talked about 19 before, and it, again, beats the measured plants, because 20 the 90 is a measured number, not an estimated number. The 21 120 is a measured number.
22- This is an estimated based on conservative -- it 23 would be nice if we had a plant that I could bet my l l
24 paycheck, but -- l 25 CHAIRMAN BARTON: You ought to try it, because 1 ANN RILEY & ASSOCIATES, LTD.
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i 96 l 1 you've got a couple, today, boilers that are beating that
()
,~
2 3
number, which ought to make you ashamed of that number, I think.
4 DR. WALLIS: This is to a person?
5 MR. WINTERS: Total to the plant, accumulated 6 total. li 's total accumulation over all the people that 7 work there for a whole year.
8 DR. WALLIS: For one person?
9 CHAIRMAN BARTON: No.
10 MR. WINTERS: One person can't do all this.
11 CHAIRMAN BARTON: If we were the plant staff at 12 this AP600, if we were the whole staff, that's what we'd get 13 a year.
14 MR. WINTERS: All of us together would accumulate.
15 CHAIRMAN BARTON: Would accumulate that much in a 16 year. That's what that number represents.
17 DR. CARROLL: Nobody can exceed 5.
18 MR. WINTERS: Even in an accident situation.
)
19 DR. WALLIS: So, this is normal operation. !
20 MR. WINTERS: Right. This is the normal operation 21 box.
22 DR. WALLIS: It looked to me as if it was more 23 dangerous than the accident situation.
24 MR. WINTERS: No , because this is accumulated over I 25 all the people on the site, and during a refueling outage, i
['
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97 1 for example, you have hundreds of people each getting their 2
[O little bit.
3 DR. WALLIS: This is not a normal year. This is a 4 refueling year.
5 MR. WINTERS: Yes. This is a hot year.
6 Maintenance is in here, too, including the steam generator 7 -- some of steam generator's in here and some of steam 8 generator's in here.
9 Now, obviously, we didn't take the hot boilers.
10 Okay. 1
{
11 Now, for accidents, based upon our shielding and 12 the zones we have, this last bullet's for accidents, and for 13 all required operations following an accident, including i
14 getting samples in three hours and those types of things, we k 15 meet the requirements on the 5 rem whole-body and the 75 rem i 16 to extremities.
17 DR. CARROLL: Now, going back to normal operation, 18 in this certified design, you're committing, in effect, the 19 COL holder to do certain things that are going to cost him 20 time and money to keep exposure down to these levels, okay?
21 MR. WIh7ERS: Right.
22 DR. CARROLL: Now, sometime during the life of 23 this plant, we figure out that low-level radiation isn't the l 24 big problem we thought it was. How does he get out of that?
l 25 If, for example, we decide that our whole-body exposure O
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98 1 limits can be substantially higher than this --
s
[Oi 2 DR. SEALE: Could you speak up a little bit, Jay?
3 I'm deaf in my ears because of my allergies.
4 DR. CARROLL: I've got a few of them, too.
5 DR. SEALE: I can't hear you.
6 DR. CARROLL: I'm saying, if we decide someplace 7 down the road that low-level radiation isn't the big problem 8 we've been ALARAing to death and all that sort of thing, how 9 does the licensee get out of this? I guess he has to go 10 through an amendment process.
l 11 MR. WINTERS: It wouldn't be an amendment to the 12 certification. The certification provides a design that, if 13 used as we suggest, will give you these kind of numbers.
14 DR. CARROLL: But I don't need those kind of
,O V 15 numbers now.
16 MR. WINTERS: Right. And he can use them however 17 his COL or his compliance with 10 CFR 100, 10 CFR 20 rules 18 allow him. You wouldn't change the design to give him a 19 worse design. You'd just use this design in a different 20 fashion.
21 DR. CARROLL: But I'm sure you have committed him 22 to some procedural kind of things.
23 MR. WINTERS: We've committed him to procedural 24 guidelines such as, when taking a sample three hours after 25 an accident, you have to do it in two shifts. That's all l
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I 99 l
1 we've said, that a guy goes in and starts it, then leaves, }
() 2 and another guy goes in and collects it.
3 Within those general broad guidelines that we have 4 passed on, the actual operator can do quite a bit of 5 differences.
6 DR. SEALE: Orchestration.
7 MR. WINTERS: Orchestration. We're providing, for 8 example, locked doors and locked gates for access control.
9 He can, if allowed, leave the locks off. They're there, so l
10 I don't think it affects the certification per se. It would 11 affect the operational license.
12 DR. SEALE: I'm sure that's a problem that a lot 13 of people would like to have.
14 DR. CARROLL: Well, I think I can foresee in the
) 15 life of the license of an AP600 that there is going to be 16 -some relief from the present 10 CFR 20 limits.
17 Would the staff agree with that?
.18 MR. EMCH: No.
19 DR. CARROLL: No?
20 DR. POWERS: I know one person that's extremely 21- dubious.
22 DR. CARROLL: It would be a shame if we don't look 23 at that problem very carefully and thoughtfully. It's 24 costing a lot of money.
25 MR. WINTERS: That's a very quick overview, but we 1
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l l
( _.
l 100 1 believe that we have demonstrated protection features 2.
l( ) adequate to support design certification.
3 CHAIRMAN BARTON: Jim, describe special 4 maintenance in Chapter 12, section 12.4.1.4. Is that 5 maintenance that goes beyond the routine of scheduled 6 maintenance? This schedule includes both modification of 7 equipment and upgrade to plant, repairs to failed 8 components.
9 And then you make a statement that says no special !
10 maintenance activities are forecast for motor pumps. Can 11 you explain that? These. pumps will never need overhaul, 12 maintenance, will never break in 40 years? I don't 13 understand. I i
14 MR. WINTERS: Spec.al maintenance is defined as'in
()
15 situ work.
16 CHAIRMAN BARTON: Oh. So, I take this motor pump l 17 out and I take it to a low-dose area and completely overhaul 1
l 18 it, and it's hot as pistol. !
19 MR. WINTERS: The idea would be to take it to some 20 other facility or just replace it. The plans that we have 21 do not include refurbishing of main coolant pump on-site.
l 22 We do have the carts and the maintenance paths and the 23 removal paths identified to take out the pump. We've 24 analyzed what doses people would receive by removing a pump 25 and putting in a new one, and you'd take it away. We don't O ANN RILEY & ASSOCIATES, LTD.
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101 1 anticipate doing any of that kind of maintenance on-site at
'() _2 a low facility.
3 If it made sense to refurbish that pump, it would l 4 have to do to a hot shop area that this plant doesn't have 5 the capability to do.
6 So, special maintenance does include the removal 7' of the pump.
l 8 CHAIRMAN BARTON: It doesn't include the overhaul
( 9 'or modification.
! 10 MR. WINTERS: It doesn't include the overhaul or l
l .11 the modification of that pump.
12 DR. CARROLL: Where would you do this? Who would l 13 overhaul these pumps?
14 MR. WINTERS: Well, if you could buy that service h 15 from the government, they've done a number of these, the 16 same type of pump. Commercial operation -- I don't know.
17 CHAIRMAN BARTON: That's a new business for 7
18 Westinghouse. But.that's a good question. There probably i
19 isn't many places that you could take it. The Swedes do it 20 in-house, in a hot shop they have built on-site.
21 MR. WINTERS: Our Navy has done a number of them.
22 CHAIRMAN BARTON: Send it to the Navy. That's the 23 ' answer.
24 DR. UHRIG: What about something like steam 25 generator replacement or re-tubing? Have you looked at ANN RILEY & ASSOCIATES, LTD.
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102 1 this?
() 2 3 that.
MR. WINTERS: There were estimates included for 4 As far as removing a steam generator, we have 5 designed in removal paths for a steam generator, so you can 6 get one out of this plant through the hatches, on defined 7 paths, with defined equipment, and to tell you the truth, I 8 don't know how much of that was included in special 9 maintenance arrangements, because we're not anticipating 10 removing a steam generator from this plant.
11 DR. UHRIG: They're going to last 40 years, 60 12 years?
13 MR. WINTERS: Design life of 60 years.
14 CHAIRMAN BARTON: Occupational radiation exposure
() 15 -- estimated annual occupational exposures are developed j 16 within the following categories, and it's routine operation l 17 and maintenance, routine maintenance, in-service inspection, 18 special maintenance, waste processing, and fuel handling, 19 and the thing that I don't see is any in-service testing 20 program activities. Where is that included?
21 MR. WINTERS: Included in the in-service 22 inspection.
23 CHAIRMAN BARTON: So, ISI and IST are all 24 together.
25 MR. WINTERS: Yes.
(~
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103 l 1 CHAIRMAN BARTON: Okay.
( 2 DR. SEALE: Well, there are dose estimates for 3 reactor coolant pump inspections.
4 CHAIRMAN BARTON: That's IS.
5 DR. SEALE: And reactor operations and 6 surveillance.
7 CHAIRMAN BARTON: I'm talking about pumps and 8 valves.
9 DR. SEALE: Well, there is for a pump inspection.
10 MR. WINTERS: But IST is actual operation of 11 valves, not just looking at them.
12 CHAIRMAN BARTON: But it's in your line item on 13 in-service.
14 MR. WINTERS: It's in the line item on in-service 15 inspection.
16 CHAIRMAN BARTON: Okay.
17 DR. SEALE: But there are tables on steam 18 generator eddy current tube inspection. l 19 CHAIRMAN BARTON: I was calling that ISI. I was 20 looking for pumps and valves.
l 21 MR. WINTERS: A lot of our testing on valves, Dr.
l 22 Barton, can be done from the control room, that you cycle !
23 the valve and you can -- and assuming it passes, you watch 24 the valve indicators tell you that it actually cycled. You 25 don't have to get out into the containment to do a lot of
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l 104 1 our ASME valve cycling tests.
l l( 2 DR. CARROLL: I don't think that's true, not for 3 motor-operated valves.
4 MR. WINTERS: We don't have a lot of 5 motor-operated valves. We have some, and those you probably 6 have to go out there and watch it.
I 7 DR. CARROLL: You have to go out and instrument 8 it.
l 9 MR. WINTERS: They have limited instrumentation on 10 them. So, it depends on the test you're talking about, and 11 I shouldn't have over-spoken, but it depends on the test.
12 CHAIRMAN BARTON: In another section, you say that i
13 dose will be lower in AP600 because of reduced radiation 14 fields, increased equipment reliability, and reduced number
()
15 of components. I can understand some of that.-
l 16 Can you explain to me the increased equipment 17 reliability? What's that mean? Do we have better equipment 18 that now exists? Where do I get increased equipment 19 reliability from this design? You're taking credit for it.
f j 20 MR. WINTERS: Well, we're taking credit -- in that l 21 broad category, we're taking credit for the canned motor 22 pumps, because seals and seal replacement and seal leakage 23 have always been a main coolant pump concern and reduces --
l l
24 or increases your maintenance requirements on a main coolant 25 pump.
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105 l
1 So, if you take the known reliability of main 2 coolant pumps that are canned motor pumps, from their
- 3. history, which is almost no maintenance required, to those 4 where you have to -- in the sealed pumps, even though f 5 they're different pump's, there is an increased plant l
6 reliability in just that area, for example.
I-7 CHAIRMAN BARTON: Are there more? I can ,
8 understand the canned pumps. i l 9 MR. WINTERS: I don't know off the top of my head
(
l 10 of any more.
11 DR. CARROLL: I had a question that your site l 12 layout drawing prompted that really belonged in the last 13 section.
14 There have been a number of plants, one I am quite 15 familiar with, that have a layout somewhat similar to this, 16 where the main steam lines go from the containment to the 17 turbine building and the main steam relief valves are in 18 that area, and the first time one, in testing, pops those 19 main steam relief valves, you create a considerable vacuum l 20 in that valley.between the containment and the end wall of '
21~ the turbine building, and in several cases, people have 22 actually pulled the siding off of the turbine building and
'23 sent it several hundred feet up in the air.
24 Have you given any thought to that problem?
25 MR. WINTERS: Well, first, we don't have a valley !
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I 106 l 1 The top of this building is close to that building.
2 DR. CARROLL: Oh, it is.
f( )
3 MR. WINTERS: Yes.
- 4 DR. CARROLL
- Okay.
l l 5 MR. WINTERS: Secondly, the exhaust ducts on the l
6 steam reliefs do go well above the adjoining building, well 7 above.
8 DR. CARROLL: Okay.
9 MR. WINTERS: A couple feet, at least. I don't 10 have an elevation view here, but they do stick up a ways.
11 DR. CARROLL: Okay.
12 CHAIRMAN BARTON: Any other questions?
13 [No response.]
14 CHAIRMAN BARTON: Does staff have any comments on
( ,/ 15 Chapter 12?
16 MR. EMCH: I'm Rich Emch. I'm the Chief of the 17 Radiation Protection Section in NRR.
18 Before I talk about Chapter 12 for the AP600, I 1
19 wanted to just -- a couple of things that you folks 20 commented on along the way, I thought maybe I should give 21 you a little bit more information about.
22 ALARA is defined in 10 CFR 20. Now, as a concept, 23 it has some amount of ambiguity associated with it, but it 24 is defined.
25 In practice, for occupational exposure at a ;
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107 L
1 reactor plant, actually, licensees are usually willing to )
!O
,U 2 spend a great deal more than $2,000 to reduce a man-rem.
3 The $2,000 number that was pointed out is usually associated 4 with off-site.
1 5 In practice, the -- it's usually considerably-6 higher than that, because usually associated with achieving l
i '7- a lower occupational exposure, you also achieve simplicity {
l 8 of design, faster operations, more flexible or becter 9 operations, such that there is an economic pay-off for the 10 utility, usually associated with it even beyond what they 11 might save in occupational exposure.
- 12 Your question about potential effects on --
13 whether we might say that radiation dose -- you know,
- l. 14 whether we can reduce doses in the future, I guess, was your 15 comment -- that's a possibility. I can't discount it, l 16 because obviously, over the last many years, we've had j '17 changes that have occurred, the change to the TDI concept 18 that has greatly de-emphasized use of respirators and things 19 like that in a plant.
l 20 The TDI concept also de-emphasized thyroid doses 21 based on research and experience, and there's always 22 research and debate continuing in the health physics 23 community.
24 The reason I said no a moment ago is it's just, 25 after 23 years of watching all this go on, I don't really j O ANN RILEY & ASSOCIATES, LTD.
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108 1 anticipate us ever moving away from the ALARA concept 2 completely.
3 I think there will always be some belief that 4 there's some damage associated with any amount of radiation 5 exposure.
6 DR. CAPROLL: It's going to be hard to sell plant 7 workers on that, though, if, in fact, their doctor.
8 recommends that they receive supplemental exposure to get up 9 to an optimum amount of radiation in their lives.
10 CHAIRMAN BARTON: You're really stretching, Jay.
11 DR. CARROLL: I foresee that happening. There's 12 some serious proposals.
13 DR. POWERS: Maybe Mr. Carroll should familiarize 14 himself with a study that recently came out of the UCLA 15 School of Public Health.
16 DR. CATTON: Suspect already.
17 DR. POWERS: I assume it was heavily endorsed by 18 the thermal hydraulics community within the UCLA campus.
19 MR. EMCH: I won't comment any further on that 20 one.
21 Now, as far as Chapter 12 for the AP600, one point 22 I did want to make here is that, as opposed to the ABWR and 23 the System 80+ designs, AP600 did put a lot more effort into 24 identifying in more detail the sources of direct and 25 airborne radiation or radiological exposure to the workers,
[~
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- l 109 1 and at some point when we're discussing ITAAC with you, I
() 2 think you'll see that much different ITAAC.
3 They don't have -- they won't have the radiation 4 protection DAC that you saw for the others. They did do a i
5 more detailed design in this area, and we consider that 6 good. 3 7 As far as their estimates of annual exposure, the
! 8 67 number, whatever you were looking at a moment ago, 9 experience with current designs would suggest that they will 10 be -- that the AP600 will be able to be run in that-range 11 with the' proviso that they don't have significant steam 12 generator problems. You know, that's the one thing that 13 would really vault that number out of that range if they ran ,
i i
14 into that. !
O
, (_ ,/ 15 Other than that, I don't think we have any 16 particular comments.
17 Thank you.
i 18 DR. SEALE: I would be interested in your 19 assessment of the value of specialized surface preparation 20 and these kinds of intervention and interdiction on pathways 21- for contamination and so on.
i 22 Mr. Barton, I think you've got more experience 23 than anybody else in this room with the consequences of 24 contamination and the control of contamination.
25 DR. POWERS: One of the problems, Bob, I think you
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110 1 quickly run into on piping system surface preparation for
[G) 2 the purpose of contamination control -- and you're quite 3 right -- things like electro-polished surfaces are much less 4 absorbent than anything else you can do -- is that those 5 things quickly get undone as soon as you put a weld in the 6 system, and so, you can electro-polish all you want to, and 7 the weld just undoes everything.
8 DR. SEALE: Certainly, insulation is not exactly 9 an easily cleanable surface.
10 DR. POWERS: I think the things that may give you 11 big bang for the buck are simply piping system design to 12 assure that you don't have.either cold or low spots where 13 you get --
14 CHAIRMAN BARTON: Crud traps.
15 DR. POWERS: When you talk about surface 16 preparations within the occupiable portion of it, epoxies 17 and things like that, you start running into all kinds of 18 problems with fire loads when you start doing those sorts of 19 things. It doesn't take much poly-urethane and whatnot on a 20 floor to get your fire load right up there.
21 The sad tale it, when you've had those failures 22 throughout the system, then you really pay for it in the 23 long run.
24 DR. CARROLL: Dana, even after poly-urethane is 25 cured, it's still a big fire load?
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111 1 DR. POWERS: I think you can't discount it from
( 2 fire load. I wouldn't. I don't know what the staff does, 3 but I wouldn't.
4 DR. CARROLL: Even on the floor?
5 DR. POWERS: I wouldn't.
6 CHAIRMAN BARTON: Any other questions?
7 [No response.)
8 CHAIRMAN BARTON: If not, we'll take a lunch break 9 till one o' clock. I'd like to clear the room, if possible, 10 and just keep the committee members here and talk a little 11 bit about the security plan we're going to hear tomorrow, if 12 that's legal.
13 [Whereupon, at 11:36 a.m., the meeting was 14 recessed for lunch, to reconvene this same day, Tuesday,
() 15 March 31, 1998, at 1:00 p.m.)
16 17 18 19 20 21 22 23 24 25 O
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112 1 AFTERNOON SESSION 2 [1:00 p.m.]
3 CHAIRMAN BARTON: We are back in session this 4 afternoon. Westinghouse will present SSAR Chapter 15 5 Accident Analysis. Brian, are you ready?
6 MR. MCINTYRE: Yes. We have three presentations 7 today for Chapter 15. The first is going to be on the LOCA
.8 analyses, the second is going to be on non-LOCA, and the 9 third is on the radiation dose calculations.
l 10 The first presenter is Bob Kemper, in the LOCA ,
! 11 area.
I 12 MR. KEMPER: I'm Bob Kemper from the Safety 13 Analysis Engineering Department at Westinghouse. I will be 14 kicking off our presentation on Chapter 15 by talking about .
15 the loss of coolant accident results that you find there.
16 The history of modern LOCA analysis, so to speak, l
17 really dates back to the rule-making days in the early '70s, 18 which led to 10 CFR 50 coming out. One of the requirements- ,
19 in Appendix K there says that a spectrum of the possible 20 pipe breaks need to be analyzed, up to and including the 21 rupture of the largest coolant pipe in the plant.
22 In our analysis, we have considered, with 23 different methods, the large-break LOCA, which is an ANS 24 Condition IV event, and the small-break LOCAs.
25 The acceptance criteria are found in 10 CFR 50.46.
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113 1 They deal with the fuel; in particular, the peak cladding 2 temperature must not exceed 2200 degrees Fahrenheit. There 3 are limits on oxidation, both locally and core-wide, and 4 core cooling needs to be provided in the long term.
5 For the AP-600 analyses in Chapter 15, the safety 6 systems alone have been modeled. So what that means is that j 7 we're considering the passive safeguard systems with which 8 the plant is equipped. The limiting single failure is l 9 assumed in the analyses, as per the regulation. what you 10 will see as I go through here is that non-safety-related 11 systems, such as the charging pump for the RCS or the 12 startup feedwater system, are not modeled in this analysis 13 because they are not safety systems in the plant's design.
14 DR. KRESR: With the automatic de-pressurization 4 15 system, does that make the small-break LOCA look at lot like 16 the large-break LOCA or do you have to assume something 17 about its failure?
18 MR. KEMPER: Well, in the small-break LOCA 19 analyses, the limiting single failure is one of the Stage IV 20 valves.
21 DR. KRESR: So you fail one of the Stage IV vales.
22 MR. KEMPER: Right. That is the limiting single 23 failure that we have identified for the small-break LOCA, 24 and that's because it does inhibit your capability to 25 depressurize.
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114 l
- 1. To highlight briefly the features of the plant
,( ) 2 which play into the calculated ECCS performance. First of 3 all, the plant has a low power density cole. This is 4 typically about 20 percent below what a modern plant would 5' have. So this is one factor that plays into the ECCS 6 performance.
i 7 We have, of course, the canned motor reactor 8 coolant pumps instead of the shaft seal pumps of current 9 Westinghouse plants. As I mentioned before, the 10 safety-related systems are passive systems in this plant.
I 11 More specifically, for the safety injection, we would have I i
12 core makeup tanks which more or less replace the function 13 that a high head safety injection pump would have in a 14 conventional plant. These provide gravity injection and
() 15 system pressure when they are activated by the appropriate 16 signal.
17' Accumulators are pretty comparable to the current 18- plant. As Dr. Krefts mentioned, the key in this design is 19 the stage de-pressurization for small-break LOCA events to 20 containment pressure, so that the IRWST, which is actually 21 in the containment, can actuate by gravity.
22 In the long term, there are still no pumps 23 involved in the safety-grade design of the plant. So there 24 is recirculation, what we call containment recirculation 25 from water that's present within the containment, entering i
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115 1 through the safety injection piping, direct vessel injection
() 2 line, and then venting being provided through ADS Stage IV.
3 We mentioned briefly the ADS before.
j 4 MR. WALLACE: Can I ask you about these other l
l 5 things first? What we see in this large volume here is a 6 whole lot of sort of concrived scenarios and then these 7 systems respond in some way. But in the design process, 8 someone chose to have core makeup tanks of a certain size to l
9 perform some function. It's not a result of a synthesis of 10 all these postulated breaks that these things were designed.
11 Two thousand is too big a round number.
-12 Where did it come from? Was it just CMTs there to 13 take care of a certain function and then the accumulator 14 takes care of another function, which is identifiable in
() 15 some general way independent of the details of the accident?
l 16 MR. KEMPER: In the context of a loss-of-coolant 17 accident, the CMTs function as providing inventory as most i 18 important. It also provides boron injection for --
19 MR. WALLACE: How did someone decide there should l
20 be 2000 cubic feet?
21 MR. KEMPER: Maybe Brian can address that.
22 MR. MCINTYRE: It was through -- there were a 23 series of optimization studies that were done, where we 24 tried different sizes, and this has been quite a while ago.
25 MR. WALLACE: You tried all kinds of sizes and ran O ANN RILEY & ASSOCIATES, LTD.
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116 l' all sorts of accidents and came up with a round number of 2 2000.
l 3 MR. MCINTYRE: It's a good round number. Not 4 being' facetious, but we probably could have come up with 5 1875 or 2000.
6 MR. WALLACE: I'm asking because it would reassure 7 me if you could sort of say that although there's all these 8 things you have to do with these break analyses, everything 9 is fine because no matter what happens, the CMTs take care 10 of this and the RSC takes care of that. So no matter what 11 happens, everything is fine.
12 DR. KRESR: But kind of that is the case. If you 13 look at some of the analyses on just trying to keep the core 14 covered, they cover different periods of time.
() 15 MR. WALLACE: Is there somewhere you can get this 16 perspective?
17 MR. KEMPER: I can add this slide later perhaps.
18 MR. WALLACE: Maybe not today, but it would be 19 very nice for me to get that perspective, rather than trying 20 to work it back from all these.
21 MR. MCINTYRE: I think the answer, the best answer 22 to this will be when we talk about Chapter 6, which are the 23 engineering safeguards features.
24 MR. WALLACE: You will cover that.
25 MR. MCINTYRE: I realize that this is almost a ANN RILEY & ASSOCIATES, LTD.
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117 1 little backwards, but Terry Schultz will stand up and he
() 2 will explain that really the core makeup tanks are sort of 3 equivalent to the high head safety injection pumps in the 4 current plant.
5 MR. WALLACE: They perform this function.
6 MR. MCINTYRE: Yes.
7 MR. WALLACE: Good. We'll get to that then.
8 MR. KEMPER: To complete our roster of the passive 9 features, the AP600 is equipped with a passive residual heat 10 removal heat exchanger, which provides heat transfer from 11 the primary system into the IRWST, and that replaces the 12 auxiliary feedwater into the steam generator secondary side 13 that is typical of current day plants.
14 )
MR. CARROLL: Now, you really do have that ]
(~T I
( ,) 15 feature. You just haven't made it safety grade.
16 MR. KEMPER: Yes. The startup feedwater is 17 present and, in fact, the control system would say activate 18 me to the startup feedwater in these scenarios, but it's not 19 credited in the events I'm talking about.
20 The other point to make on passive safety systems 21 is that in the long term, for the safety design basis, the 22 ultimate heat sink is heat transfer through the containment i
23 shell to the surrounding environment. So on a safety-grade 24 basis, that is the removal of heat to the ultimate heat i 25 sink.
)
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118 l t
1 MR. CARROLL: In fact, you have fan coolers and 2 you also have containment spray.
3 MR. KEMPER: The containment spray,' I think, is
-4 really only considered to be actuated under severe accident 5 conditions. There is one fan cooler that would be available 6 to run in the long term if, again, it's not safety-grade.
7 So that would be available, if it's available.
t 8 MR. CARROLL: And it is designed to operate in the 9 post-accident containment environment.
10 MR. KEMPER: Yes. It does have a -- we have fan 11 coolers for the normal function during plant operation and 12 then there is a post-accident mode for this, as well.
13 MR. CARROLL: Okay.
14 MR. KEMPER: Reactor coolant system. This is the 15 AP600, two hot leg, four cold leg design, with steam 16 generators. I might point out that this -- what you see 17 here, that isn't really identified, is one of the two direct l
18 vessel injection nozzles by which 180 degrees apart, the 19 passive safety systems provide the CMT or accumulator water 20 or IRWST at various times in the transient through the 21 reactor vessel.
]
22 This highlights the AP600 safeguards systems and 23 in the event that we did have an accident, and I will speak 24 particularly to a LOCA, and the safeguards S signal was 25 generated, the valves which isolate the core makeup tanks ANN RILEY & ASSOCIATES, LTD.
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119
[
1 would open and --
(m) 2 MR. WALLACE: Could I ask about this S signal?
3 Excuse me. It appears throughout this whole volume here.
4 It's assumed that it happens?
MR. KEMPER: In the --
6 MR. WALLACE: Or the ways in which the S signal 7 could fail to happen.
8 MR. KEMPER: There is redundancy in the design l 9 such that that would not be postulated to occur under our 10 deterministic --
11 MR. WINTERS: This is Jim Winters. There is no 12 single failure that any -- no postulated single failure that 13 will not allow an S signal to happen as opposed to --
14 MR. WALLACE: So if the S signal were to fail, it
>Q i 15 would have to be a result of some multiple failures.
s /
16 MR. WINTERS: Right.
17 MR. WALLACE: Which someone has decided cannot i
18 happen or not to be considered to happen.
19 MR. CARROLL: Not to be considered for design 20 basis accident purposes.
21 MR. WALLACE: I'm pretty sure it will occur, but 22 it's just that someone has looked at the possibility of the 23 S signal not occurring.
24 MR. MCINTYRE: I think Jay had the right answer to 25 that, that you get into the non-design basis and into the
/~ '
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120 1 PRA studies at that point.
2 DR. FONTANA: That's a question that I had as I !
3 was going through here. I saw quite a few places where 4 things were not allowed to happen because of single failure 5 criteria or operators did this or did that. The question 6 is, is every one of them picked up in a PRA or has there 7 been an attempt to really seam them together? The answer is 8- yes?
9 MR. WINTERS: Yes.
10 .DR. KRESR: Basically, the way you could view that 11 is the PRA validates the implied assumption that if you use 12 this process, that you will end up with a safe plant. The 13 PRA just is a way.to validate that assumption.
14 MR. WALLACE: The only interesting processes.are 15 not the ones that you've analyzed here. They're the ones 16 that actually do lead to a significant accident. So the 17 only ones which are sort of real interest are the ones which 18- are not considered. They have to be in a PRA somewhere.
19 MR. KEMPER: They are considered in PRA space, I 20 guess is the answer.
21 MR. WALLACE: That's where it has to be. That's 22 not part of --
23 MR. CATTON: But even the PRA misses the one you 24 don't think about.
25 MR. WALLACE: Like the operator action.
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121 1 MR. CATTON: Yes.
() 2 DR. KRESR: The PRA has its limitations. A lot of 3 these questions you have, Graham, would be addressed in the 4 PRA. We haven't reviewed the PRA yet.
5 MR. WALLACE: That's a separate thing?
6 MR. MCINTYRE: Yes.
7 MR. KEMPER: Yes. So to calibrate you, this is 8 the design basis safety analysis from SSAR Chapter 15, and 9 the PRA is a separate realm.
10 MR. MCINTYRE: This is more of the stuff we're 11 required to do.
12 MR. CARROLL: And, in fact, design basis accidents 13' really aren't very interesting. You have to get into severe 14 accident space before you are really getting into
() 15 consequences that adversely affect public health and safety.
16 DR. KRESR: That's because, by definition, design 17 basis accidents have to be designed again.
18 MR. CARROLL: Yes.
19 MR. KEMPER: Or to phrase it a little differently, 20 the AP600 has been designed such that no single act of 21 failure can do bad things to you in the realm of design 22 basis accident analysis.
23 Okay. So core makeup tanks are the first part of 24 the passive safety injection system that would become active 25 during a LOCA event. As mentioned before, we're looking O ANN RILEY & ASSOCIATES, LTD.
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l 122
, 1 here typically at one of two, with redundant similar systems r-(%) 2 being provided via direct vessel injection lines other 3 either side of the reactor vessel.
l 4 For a small-break LOCA, in the initial portion of 5 the event, you still have liquid in the cold legs. So in 6 small-break LOCAs or in non-LOCA events, a phenomenon begins 7 in which the valves are open and you get what's called --
8 what we call, anyway, a recirculation flow from the cold leg 9 through the core makeup tank and then the cold water from 10 the core makeup tank, which is rich in boron, entering the 11 vessel through one of the two DVI lines.
12 MR. CARROLL: That all assumes that the check 13 valves will operate against the very low differential 14 pressure there.
15 MR. KEMPER: That's correct.
16 MR. MCINTYRE: Which check valves? '
17 MR. KEMPER: There are check valves located here.
18 MR. MCINTYRE: Those check valves are biased open.
19 MR. KEMPER: Yes. I believe they're tilted.
20 MR. MCINTYRE: Yes, they are.
21 MR. CATTON: Also, Jay, it depends on whether or 22 not you get the block valves open.
23 MR. CARROLL: Of course.
24 MR. MCINTYRE: The two parallel block valves, yes.
25 MR. CARROLL: And those are air-operated valves or ANN RILEY & ASSOCIATES, LTD.
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'l 123 1~ motor-operated?
() 2 MR. MCINTYRE: They look like air-operated.
3 MR. CARROLL: It looks like air to me, yes.
4 MR. KEMPER: Yes. I believe so.
1 5 MR. MCINTYRE: The low delta P check valve problem l 6 we think has been addressed by designing it out of the 7 plant, and Terry Schultz will talk about that when he does j 8 Chapter 6.
9 MR. WALLACE: So this comes in because the cold 10 water in the tank is heavier than the stuff in the balance j 11 line, j 12 MR. KEMPER: That's right.
13 MR. WALLACE: It's a very slow start and then it 14 gets going.
) 15 MR. KEMPER: That's right. You would --
l 16 typically, from one of the tanks, if you have the tanks, if l
17 you have the natural circulation with hot water replacing 18 cold, the rate of injection is on the order of 60 pounds a 19 second, from each of the CMTs, when it's in this 20 recirculation mode.
21 MR. WALLACE: There is no way in which the balance 22 line can get cold enough so that nothing happens. It goes l 23 in backwards or stalls.
l 24 MR. KEMPER: Not in LOCA space. You're always --
25 this is typically 120-degree water temperature maximum, O
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1 124 !
l 1 based on the -- in the tank.
() 2' 3
~MR. WALLACE:
is the pressure --
That's in the balance line. How hot l
4 MR. KEMPER: There are thermal requirements on the
- 5. temperature in that balance line to assure that up to the i very' top that it meets a minimum temperature restriction, so 1
6 1
7 that you will, in fact, will begin the process.
8 MR. WALLACE: If it's sitting there a long time, 9 is there any chance of gas forming in that top of the line 10 there?
5 11 MR. CARROLL: Yes.
12 MR. KEMPER: I believe there is a vent for that.
i 13 I don't know what the specifications for the plant would 14 indicate.
) 15 MR. WALLACE: I'm sorry. I could have a thousand 16 questions. I just have to be quiet.
l 17 MR. MCINTYRE: I think the actual system design is '
l 18 a Terry Schultz question, j 19 MR. WALLACE: There still won't be enough time.
i 20 MR. CATTON: How big is that vertical line?
21 MR. KEMPER: This line would be eight-inch on 60 l 22 pipe, so it's basically seven inches inside diameter. l l
23 MR. CATTON: You will have a continual refluxing 24 into that line the hot to cold leg. So it's going to be I 25 pretty warm in that line.
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1 !
1 125 1 MR. WALLACE: Where does it go? l
() 2 3
MR. CATTON:
you have hot water.
Well, it sits in the top and below it So you're going to have cooling on the 4 boundaries of the pipe and it keeps running down and 5 dripping into the other one. You'll get an up-flow of the 6 hot fluid. Eight inches is pretty big for water, for 7 natural convection in water.
I 8 MR. WALLACE: But the de-gassing is --
9 MR. CATTON: That's a separate concern. )
10 MR. WALLACE: I'm sure he's taking care of it.
11 MR. KEMPER: Okay. During the LOCA event, you 12 would, as the system depressurizes, reach a point of 13 accumulator injection. Again, the delivery is through the 14 same DVI connection, similar to conventional plant design.
15 Nothing too much different here.
16 The goal eventually is to, for any size break, 17 depressurize the primary system to the point that you can 1
18 get gravity injection from the in-containment refueling i 19 water storage tank, which would provide, based on the head 20 of water at containment pressure, injection through the DVI 21 lines and do that on a continuous basis until such time that 22 that tank would reach a low level condition.
l 23 In order to co that, we need a -- for the l
l 24 smaller-break LOCAs, to have an automatic de-pressurization 25 system, the first three stages of which are located at the (n
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126 1 -- on top of the pressurizer here, and activation of ADS
() 2 Stage I is based on reaching a low level within the core 3 makeup tank.
4 So that during a LOCA event, after the end of the l
5 recirculation period, which is usually when you've voided l
6 the cold leg here and the liquid in this tank has been 7 heated up by the recirculation process, steam will replace l 8 the water in the tank and level will come down until the 9 signal to activate ADS Stage I is received.
10 At that point, you begin a process to open States 11 I through III in a staged fashion. There are timers to 12 sequence the opening of Stages II and III once the signal-to 13 open Stage I has been received.
14 The effluent from the pressurizer is delivered
() 15 into the IRWST through, if you can read that, spargers, two 16 of which are located in the IRWST below the liquid surface.
17 MR. WALLACE: What is in the line between ADS I, 18 II, III and IRWST before they open?
19 MR. WINTERS: Air, except up to the level of the 20 IRWST.
l 21 MR. WALLACE: There's a vacuum breaker or 22 something, what's in that?
23- MR. KEMPER: There is a vacuum breaker in the 24 piping arrangement here.
l 25 MR. WINTERS: Yes.
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127 l- 1 MR. WALLACE: So there's gas in there, f
( 2 MR. KEMPER: These valves would be --
! 3 MR. WALLACE: So there's air in that pipe.
- _ 4 MR. WINTERS
- Yes.
5 MR. KEMPER: Not shown on this diagram is the PRHR 6 heat exchanger, which receives fluid from the hot leg.
7 MR. WALLACE: Excuse me. Is there some leak 8 detection on ADS I, II, III, if they were slowly leaking 9 into that pipe? There must be.
10 MR. MCINTYRE: It's leak detection by temperature.
11 There is a temperature indication downstream of the valves.
12 It's anticipated. Those valves sit right on top of the 13 pressurizer, that there is no chance for it to cool off. If 14 there is something leaking through, this should be able to 15 see it.
16 MR. KEMPER: Along that line, too, I might point 17 out, you see two valves in series here. The first one is 18 what, in our terminology, an isolation valve, which is a 19 gate valve, the intent being to try and make sure that there i
l 20 is no leakage.
21 MR. WALLACE: So you have cold water in the 22 horizontal leg coming out of IRWST. That horizontal run.
23 MR. CARROLL: It's a schematic.
24 MR. KEMPER: It's a schematic.
25 MR. WALLACE: Well, of course, the real part may ANN RILEY & ASSOCIATES, LTD.
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128 1 be weird and wonderful in terms of collecting. I'm just
() 2 wondering.about steam / water interaction in that pipe there.
3 Sometime.
4 MR. KEMPER: The sparger essentially, the arm is 5 out like this --
6 MR. WALLACE: But the water level is higher than 7 that. So that pipe is full of cold water. I'm going to 8 have to restrain myself, because I have questions on almost l 9 everything here.
10 MR. KEMPER: I don't really recall exactly the 11 piping arrangement.
12 MR. CARROLL: I would expect that to be a downward 13 sloping _line.
14 MR. WALLACE: Which way does it slope?
() 15 MR. CARROLL: No. I don't think there is a 16- horizontal run at all probably.
17 MR. MCINTYRE: The run c0mes off of the ADS 18 package. It almost immediately runs down the wall, then --
19 I don't know how many feet it is, it's a few feet until it 20 gets into the IRWST. Then it runs at a downward sloping run 21 that's more or less horizontal under the water level to 22 where it drops again to go into the sparger. !
l 23 Once it gets in the IRWST -- it runs mostly down )
24 till it gets in the IRWST. Then it runs not horizontal, but 25 sloping down slightly till it gets around to where the g s ANN RILEY & ASSOCIATES, LTD.
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129 1 spargers are and then it goes straight down again.
() 2 3
MR. KEMPER: The sparger is a long, straight, vertical pipe anc this is a reasonably long distance here.
4 I know some of this piping is sloped in a downward 5 direction.
6 MR. WALLACE: So if you had a slow leak, it would 7 suck water back into that line, presumably.
8 MR. CARROLL: I think you've got a vacuum breaker.
i 9 MR. WALLACE: So there's a vacuum breaker.
10 MR. KEMPER: Yes. There is a vacuum breaker 11 associated with the piping design.
12 MR. POWERDR. SEALE: I should know, but just to 13 remind me, what does the sparger actually look like?
14 MR. KEMPER: I did a bad definition of it before.
) 15 I think it's four -- on the sparger body, you have like four 16 --
17 MR. MCINTTRE: Downward-sloping arms.
18 MR. KEMPER: -- downward sloping arms.
19 MR. MCINTTRE: Holes drilled in the bottom of 20 them.
l 21 MR. KEMPER: With holes around the circumference 22 of the sparger pipes.
t 23 MR. WALLACE: Like the one at OSU.
24' MR. MCINTYRE: The main arm piping is like, what,
-25 Schedule 40 pipe, a foot in diameter, six inches?
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130 1 MR. MCINTYRE: It's bigger than six. I'm just
() 2 trying to remember what. It's something like that. It's
( 3 more than Schedule 40.
4 MR. POWERDR. SEALE: More than Schedule 40. Okay.
5 MR. KEMPER: But it is a low pressure application.
6 MR. WALLACE: So this is one of the places you 7 minimize --
8 MR. POWERDR. SEALE: I should know.
9 MR. MCINTYRE: I think it's like five-eighths of 10 an inch, sticks in my mind, that type.
l 11 MR. WALLACE: Is this one of the~ places you 12 minimize water hammer?
13 MR. CATTON: The reason for the cruciform -- and 14 that's probably not the word you use -- is that the steam 15 jets into the pool are small and they avoid chugging.
16 Without them, they get some pretty exciting action inside.
17 MR. KEMPER: And there were tests performed in 18 Italy to identify sparger performance and --
19 MR. CARROLL: Full-scale.
20 MR. KEMPER: Full-scale.
21 MR. WALLACE: I was more concerned with the leak 22 situation, where you had a very low steam flow rate and the 23 water comes charging back up the line. This is usually a 24 place where you minimize water hammer, as we heard this 25 morning.
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131
-1 MR. CARROLL: No. This morning we were talking
() 2 about water hammer in the feedwater system.
3 MR. WALLACE: I know, but it's a generic thing.
4 Water hammer doesn't appear in this book at all, the word, 5 whatever it does, the FSAR.
6- MR. MCINTYRE: Tha SSAR. Yes, I'm sure that it 7 does.
8 MR. WALLACE: I haven't seen it.
9 MR. MCINTYRE: We all it a dynamic effect or 10 something. Very seldom there is water hammer in there.
11 This question about leaking through two valves in series, 12 and we do have a connection between the valves to check for 13 accumulation of water between the two on a period in-service 14 arrangement. Yes, there could be leakage, and, yes, what 15 you're talking about could happen, but with the in-service 16 inspection routine that we have and the fact that we do 17 check between the valves to see if water is accumulating, 18 that's not something that is going to go long unnoticed.
19 MR. CATTON: What would happen if that line
~20 ruptured?
21 MR. WALLACE: It would go into containment, 22 presumably.
23 MR. CATTON: Well, it would impact the 24 containment, but how much? Is that something that you've 25 looked at?
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132 1 MR. MCINTYRE: Which that line?
I
) 2 MR. CATTON: I'm pointing to the line up there 3- that's right where his pencil is.
4 MR. CARROLL: There ain't much pressure in there 5 because the sparger is open at the bottom.
6 MR. CATTON: Well, but, you see, when the ADS 7 system is actuated --
8 MR. CARROLL: Now you want to actuate it.
9 MR. CATTON: That's right. If it's not actuated, 10 who cares. You go up and you fix it. But if it's actuated 11 and you get a large water hammer and you rupture the pipe, 12 what's it going to do to you? Maybe not much.
13 MR. KEMPER: Well, you'd put this energy and mass 14 into containment.
15 MR. CATTON: Is that something that's been i 16 considered?
17 MR. KEMPER: Let me think. Well, it's no more 18 . mass energy than would go in in a large-break LOCA.
19 MR. CATTON: You're already up to within a half a 20 psi of your design of pressure under containment. Would 21 that push you over the edge?
22 MR. MCINTYRE: No. It certainly would be less l
23 than a large LOCA, than the 230, whatever diameter inch l
24 pipes there are.
25 MR. CATTON: But it's in a different place. l l
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133 1 They're different. I guess this is a question to save for
() 2 the thermal hydraulics subcommittee meeting.
3 MR. WALLACE: I think the more important part is 4 what is the answer.
'5 MR. CATTON: Well, we know what the question is, 6 and they don't_have an answer right now.
7 MR. KEMPER: The only answer.I can give now, not 8 being involved in the containment analycis, is I know they 9 did look at some small-break events relative to our -- is 10 there something more limiting than the classic double-ended 11 LOCA in terms of containment response, but I don't know, I 12 can't answer your question about if something like a rupture 13 of this pipe might have been considered.
14 MR. CATTON: It's high up in the containment, the 15 other one-is low down on the containment.
16 MR. WINTER: A steam break is higher in 17 containment. Not quite as high as this, but it's up there, 1
18 and that's much bigger pipe with much more energy and mass, '
19 and we pass containment with a steam line break.
20 This pipe clearly is over-designed because it's 21 not designed for atmospheric. It's designed for the 22 pressure, and it's small compared to a steam line and 23 compared to a double-ended break low.
24 MR. CATTON: When you actuate your ADS, you may 25 get pressures in that line that-are pretty damn near l
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134 1 whatever the system pressure is.
( 2 MR. CARROLL: That's right.
3 MR. CATTON: During the period that you're 4 clearing the-water out of the line so the steam can get 5 through.
6 MR. MCINTYRE: Remember, the valves open in stages I
7 very slowly. The first valve is an air valve.
8 MR. CARROLL: Air gets out of there very slowly, 9 too. You've got to push it out.
10 MR. WINTERS: Right.
11 MR. CATTON: So there's a lot of things that play 12 a role in what that pressure is going to be.
13 IW1. WINTERS: And that's why we believe, in our 14 full-scale test, that --
15 MR. CATTON: You didn't test this full-scale.
16 MR. WINTERS: The valves were the right size, the-17 pipe was the right size.
18 MR. CATTON: Were all the elevations correct?
19 Then what did the pressure get to be in that line.
20 MR. WINTERS: I don't know what that is here, but l 21 that's a --
22 MR. CATTON: Well, I don't either.
23 MR. WINTERS: It wasn't near system pressure on 24 the downstream side of that valve package.
25 MR. KEMPER: There was a large drop across the I
l
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135 1 valve, particularly at the start, when you have the highest
- 2. pressure.
3 MR. CATTON: At the start when the valves open up 4 and you haven't cleared the water from the line, the 5 pressure builds up. pretty high and you don't get a whole lot 6 of pressure drop because you don't have a whole lot of flow.
7 You get the pressure drop once you've cleared and 8 you start to get flow. So there's an initial peak in the 9 pressure. Jay knows all about this.
10 MR. CARROLL: That's the way pressure suppression 11 containments work.
- 12. MR. CATTON: But the pressure suppression 13 containment on the SRV, it will go straight down. There is 14 no horizontal runs or anything. Now, that horizontal -- if 15- you have a long horizontal run, it's probably full of water 16 and you've got to clear all that water.
17 'MR. CARROLL: No, they don't.
18 MR. WALLACE: Doesn't the staff ask you questions 19 like this or do they just check off on some list of !
i 20 predetermined things? I l
21 MR. MCINTYRE: They looked at the EDS' test !
22 results.
23 MR, KEMPER: There was a full-scale investigation 24 of phenomena within the piping in the IRWST.
25 MR. WALLACE: Because one might expect that -- we O ANN RILEY & ASSOCIATES, LTD.
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136 1 just sort of, off the top of our heads, ask a question and
() 2 3
you could say we worked it out with-the staff long ago and this is the answer.
4 CHAIRMAN BARTON: Does anybody on the staff want 5 to respond to Dr. Graham'c question?
6 MR. CARUSO: This is. Ralph Caruso from the Reactor 7 Systems Branch. In the course of our review, we asked many 8 questions about the way the system operates and we asked 9 many questions about break locations and single failures 10 that could occur.
11 As a result of those questions, we expect 12 Westinghouse to do the analyses of situations like this that 13 you've just inquired about.
14 The staff believes that this particular event -- I
() 15 believe that this was likely analyzed, but I cannot refer to 16 a particular document, off the top of my head, that says i
17 that it was. But I would expect that Westinghouse would 18 have analyzed this.
19 MR. CATTON: Reassuring.
20 MR. SNODDERLY: My name is Mike Snodderly. I'm 21 with the Containment Systems and Sever Accidents Branch.
22 We're going to come in and speak later about containment 23 analysis when we discuss Chapter 6. It would be a more 24 appropriate time, I think, to go into this specific case.
25 But I think it's important to remember some things.
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1 1
137 1 As the gentleman pointed out, main steam line
()- 2 break is a very bounding accident at a higher elevation and 3 a lot more steam. We're also analyzing or we consider the 4 CO clearing loads, chugging loads, and the design of the 5 spargers, and we're going to talk about that in Chapter 6.
6 That's where that took place, looking at that design aspect.
7 And I think that'this line, as stated, is designed 8 to handle RCS pressure. It's a very strong line relative to 9 -- and also the way the containment is designed for the 10 positive energy into the containment are through the fourth 11 stage of the ADS.
12 So all of these -- I guess, again, as Ralph 13 pointed out, we would expect it to be analyzed and we could 14 go back and do some -- to find the exact documents, but I
( 15 don't -- I don't see this as being any particularly -- a 16 break that isn't bounded by other small breaks, large 17 breaks, main steam line breaks inside containment.
18 MR. CATTON: I think the bounding argument on the 19 break is a sensible one, because all kinds of bizarre things 20 can happen with one of these systems. This comment that 21 Graham made that the water literally can get sucked up 20 or 22 30 feet. It can really get exciting. But if the line can 23 break and it doesn't impact much of anything, you've sort of 24 taken care of the problem.
25 MR. WALLACE: I don't think this is probably a i
I
)
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1 i
l 138 1 problem of this design. I'm just trying to find out more of
() 2 what your motis operandi, what kind of questions you've 3 asked yourselves and you have been asked. If we can ask, 4 off the top of our head, some question that has not been 5 asked before, then that tell us something perhaps about the 6 kind of questions that have been asked before. !
7 I don't think this is probably a problem with
, 8 safety. It's more a problem with our assessment of the i i
9 procedures and completeness or something of the study.
10 MR. MCINTYRE: And the system designer is not in 11 the room.
12 MR. CATTON: That's the problem with this kind of 13 discussion. There aren't enough people here with knowledge, 1 14 perhaps.
15 MR. CARUSO: This is Ralph Caruso, once again. As 16 Dr. Catton said, I do believe that this break in the 17 discharge line is probably bounded by a break up-stream of 18 the valves in the pressurizer steam space, in terms of the ,
19 containment response or in the system response.
20 The staff, as part of its review, has done a lot 21 of -- has considered a lot of different breaks. I know that 22 we've done our own calculations of a number of different 23 break locations, to look at areas where we thought there 24 might be concern. I don't recall particularly a pressurizer 25 steam space break that was analyzed by the staff, but I
[\
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139 1 would be surprised if Westinghouse had not done an analysis
() 2 3
of a break in that location.
MR. WALLACE: So what would you do if you found 4 out they hadn't?
5 MR. CARUSO: I guess we would ask them why they 6 had not.
7 MR. KEMPER: For ECCS performance, we've 8 considered an inadvertent actuation of this system and 9 that's a limiting case in the sense of any capability, 10 because no break is available to help you reach the goal of 11 depressurizing prior to the IRWST injection.
12 MR. CARROLL: I don't know if that's the question.
13 MR. WALLACE: I'd like to move on until the next 14 question arises.
() 15 MR. KEMPER: Moving on. ADS Stage IV is really 16 the means by which you do achieve the final depressurization 17 to containment pressure and there are actually four paths 18 that are available here, originating.from each hot lag.
19 They are activated when the core makeup tank level reaches 20 the low low set point of 20 percent of the tank inventory.
21 MR. WALLACE: That's on one tank? Excuse me.
22 MR. KEMPER: That's on either tank.
23 MR. WALLACE: Either one of both.
24 MR. KEMPER: Either of the two.
25 MR. WALLACE: So that signal has to occur in order
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i 140 1 for these valves to open. If something happened and it I ')
NJ 2 didn't drain the CMT or the signal doesn't occur, then they 3 just would not open. Is that true?
l 4 MR. KEMPER: If you still had water left in the 5 CMT and --
6 MR. WALLACE: If someone had closed the block l 7 valves or something, then you'd never get the ADS-4 opened, 8 is that true?
9 MR. KEMPER: I'd phrase it differently. If you 10 postulated some failure that would preclude that, right.
11 MR. WALLACE: Well, people in other times and 12 other places have closed valves that should have been open.
13 MR. CARROLL: Well, you wouldn't get any i i
/~
14 depressurization if the valves were closed, right? You've 15 got to have a drop in level for Stage I, II and III to come 16 on.
17 MR. KEMPER: That's correct. '
18 MR. MCINTYRE: Then you would be into the 19 beyond-design basis.
20 MR. WALLACE: So if you really wanted to screw up 21 this plant, you'd make sure the CMTs couldn't drain.
22 MR. KEMPER: Well, that would do a good job of it. I 23 MR. CARROLL: Your accumulator would. Your j
(
24 accumulator would help a good deal.
l 25 DR. SEALE: Well, there's one point about this i
[3
(_ /
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141 1 whole analysis that we haven't said much about, and that is
() 2 that with respect to the PRA, probably the most diligently 3 asked question has to do with completeness.
4 The AEOD people look at initiators to convince 5 themselves that there is a mitigator or an accident response 6 of some sort down the way to assure you that, in fact, you 7 can handle that initiator. I think that's the thing you use 8 .to convince yourself that indeed these things will do their 9 job, but behind it all, of course, is you're kind of washing 10 away the boundary between design basis and severe accidents, 11 because it's kind of seamless transition.
12 MR. SNODDERLY: Excuse me. This is Mike Snodderly 13 again. I just wanted to go back to the previous question.
14 I just remembered that, a matter of fact, that line for the
) 11 5 System 80+ design, they came in with a request to downgrade 16 that line from safety-related to non-safety-related, and the 17 staff approved that exemption or that request.
18 The only reason I bring it up is that the staff 19 has looked at that particular break before and, in fact, has 20 found that break to be such that that line could be 21 declassified or reduced to a non-safety-related line.
22 MR. CATTON: So you really don't need to feed the 23 blow-down to the IRWST.
24 MR. SNODDERLY: Exactly. That's what was shown in 25 the analysis.
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142 1 MR. CARROLL: It would make the cleanup crew
( 2 happy, though.
3 MR. CATTON: But that's a separate issue.
4 MR. SNODDERLY: I think the question was what 5 would happen if that break occurred and what's the impact on 6 safety and what --
so just to give the committee some idea 7 of what that --
8 MR. POWERDR. SEALE: Let me see if I understand 9 what you said. The staff analyzed it for System 80+ and, 10 therefore, concluded you didn't have to be safety-grade in 11 AP600.
12 MR. SNODDERLY: No, Dr. Powers. As a point of 13 reference, the System 80+ has a very similar design with the 14 pressurizer leading into an in-containment refueling water
() 15 storage tank. The original design had that line being 16 safety-related.
17 They came in with a request to make it 18 non-safety-related and the staff found that acceptable, 19 based on the analysis that if that -- assuming a seismic or 20 another type of accident, that the line failed completely 21 and dumps all that energy into containment, and it was found 22 acceptable.
23 That has not been the case for AP600. I was just 24 trying to give a benchmark of does the staff look at that 25 type of a break or has it in the past.
l l
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143 1 MR. POWERDR. SEALE: Okay. I understand now.
() 2 3
MR. KEMPER:
Carroll referred to.
Speaking of the cleanup crew that Mr. {
To try and make their life easier, the 4 non-safety-grade RNS system is available or is, with a high 5 degree or probability, likely to be available. What the RNS 6 pumps could do for you would be injecting from the IRWST.
7 If you activate that before you get to the low 8 low-level tank in the CMT, you can provide the necessary 9 core cooling without ever opening the ADS Stage IV valves, 10 which are going to blow directly into containment.
11 So although this is not something that we can 12 credit in the Chapter 15 analysis, it's a design feature 13 that would hopefully never be needed, but likely would be 14 available if such a small LOCA event were to occur.
(k 15 For the safety case then, the IRWST drains and ADS 16 Stage IV valves are open, ultimately the water level in 17 containment will increase to where the injection will be 18 containment recirculation. And that's highlighted with just 19 a dash of color here to help you see it better.
20 In the longer term them, the signal from low level 21 in the IRWST would open the valves which isolate the sump or 22 containment proper from the direct vessel injection line and 23 when that happens, the water that's -- the water level in 24 containment is available to provide a long-term source of 25 water through the direct vessel injection lines and the core O ANN RILEY & ASSOCIATES, LTD.
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! 144 l
1 to cool the core with energy being removed through ADS Stage 2
i (_ )
IV.
3 MR. CARROLL: That's water plus any debris that 4 may be in it.
5 MR. KEMPER: Yes. I am aware that that has been 6 considered in the design of the screens, et cetera.
7 MR. MCINTYRE: Debris in the pumps?
! 8 MR. CARROLL: Yes.
l 9 MR. MCINTYRE: I'm sure you guys can't wait to 10 hear Terry Schultz come, because we're saying he's going to 11 answer all these questions.
12 MR. SNODDERLY: I'm Mike Snodderly, containment l 13 systems, again. It was considered, the effect of coating, 14 debris, on a sump design, and that's, again, in Chapter 6.
() 15 MR. MCINTYRE: That's scheduled for May.
16 MR. CARROLL: When you say considered, given the l 17 small holes in the fuel support plate, you consider the 18 potential plugging of a large amount of the bottom of the 19 core with debris?
l l
20 MR. MCINTYRE: That was one of the criteria for 21 sizing the screen.
l 22 MR. SNODDERLY: The fuel support plate? I'm l
23 confused what we're -- I thought we were talking about a 24 break or energy from the opening of the fourth stage of the 25 ADS, causing debris generated from insulation ending in the
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145 1 sump.
() 2 MR. CARROLL: But then that water is going to flow 3 back into the reactor vessel and flow up through the core.
4 MR. SNODDERLY: Then your IRWST has drains and l 5 filters to prevent debris from getting into the IRWST. Then I
) 6 that's the water that's going to go back into --
7 MR. MCINTYRE: We have requirements on the use of l
l 8 fibrous insulation. There's a lot of stuff that's been done l
l 9 in this area.
10 MR. CARROLL: And that's all Chapter 6.
11 MR. MCINTYRE: Right.
12 MR. CARROLL: And Mr. Schultz, is that his name?
13 MR. MCINTYRE: That's his name. j 14 MR. CATTON: Chapter 6 keeps getting bigger.
() 15 MR. MCINTYRE: It's the description of the safety 16 systems. That's a pretty big important chapter.
17 MR. CARROLL: There really is a Mr. Schultz?
18 MR. MCINTYRE: There is today.
19 MR. KEMPER: Believe me, I hope so. Yes, the last j 20 I knew.
21 MR. CARROLL: You skipped one, or did you? Yes.
l 22 That one reminded me. Down at the bottom of the air baffle, 23 are there drains so that I could -- so I can't take an ,
i 24 hand-held missile, shoot it through the side there, punch a l l
25 whole in the bottom of the storage tank, and fill that up so l
l l
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l l
146 l 1 we block the flow?
r~ \
( 2 MR. WINTERS: The answer is yes.
i s-3 MR. CARROLL: Big drains?
4 MR. WINTERS: Yes. Many drains through the 5 sidewalk, outside.
j 6 MR. MCINTYRE: What are you asking if they can do?
7 Shoot a missile through there?
i 8 MR. CARROLL: At an angle and penetrate the 9 massive containment cooling system water storage tank where 1 10 the water drains down.
11 MR. MCINTYRE: No.
12 MR. KEMPER: The storage tanks are up here.
13 MR. CARROLL: I know. I put a hole through that.
14 The water then drains.
15 MR. KEMPER: It would run down into the annulus 16 and out the drain and onto the ground outside.
17 MR. CARROLL: Which is fine. That's what I wanted 18 to hear.
I 19 MR. KEMPER: Okay. Now, to focus on Chapter 15 1
20 analysis of the LOCA event. The calculated performance must 21 comply with the established criteria and there are several l
22 methods that were used on AP600 to establish this.
23 For the large-break LOCA, recently, Westinghouse 24 has developed a best estimate methodology using the 25 WCOBRA/ TRAC computer code, which was originally generated I
[
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r 147 '
1 for the three and four loop plants and approved by the NRC.
() 2 Now, since this was our most state-of-the-art l
3 model, we've applied that to the large-break LOCA analysis t
I 4 of AP600 and under this methodology, you establish a nominal l
5 PCT value and then consider what the 95th percentile value 6 is when you've looked and analyzed the uncertainties i 7 involved in the analysis.
8 MR. WALLACE: How did COBRA / TRAC evolve as a 9 result of looking at the experiments at OSU and the SPES and 10 so on?
11 MR. KEMPER: WCOBRA/ TRAC really had its origin in 12 our desire to take advantage of the revised approach that 13 was approved in 1988.
i 14 MR. WALLACE: Was is it in the analyses which were
) 15 presented a year and a half ago or something by the INEL 16 people? RELAP kept evolving in order to fit the data from 17 these various large-scale experiments and I would assume the 18 same sort of thing must have happened at Westinghouse, 19 because the codes don't work the first time on an 20 experiment. i l
21 MR. CATTON: Graham, the big problem was not the i
22 large-break LOCA.
23 MR. WALLACE: But I'm just asking a question I've 24 wanted to ask for some time about these codes. Were they 25 fixed in 1988? Did they keep changing to fit data up to the O
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148 1 present day? How did you get assured that they're in the
() 2 best shape for this analysis?
3 MR. KEMPER: There was a large variety of test 4 simulations done of tests from the -- well, separate effects 5 tests and tests from the 2D3D program to get WCOBRA/ TRAC.
6 MR. WALLACE: Did the code evolve and get changed 7 as a result of those comparisons?
8 MR. KEMPER: Certainly. The time period we're 9 talking here is four or five years ago when a lot of that 10 was actually accomplished.
11 MR. WALLACE: Was there some sort of 12 give-and-take, where NRC said this is not acceptable because 13 it won't model SPES, and you had to explain it and you went 14 and changed COBRA / TRAC until it did model SPES and they went
() 15 around again?
16 MR. KEMPER: That really plays in the small break.
17 MR. WALLACE: Is that how this thing happened?
18 MR. KEMPER: That definitely happened with no 19 trouble for the small-break application and we'll speak more 20 about that in a bit.
21 MR. WALLACE: All that would be transparent to an 22 observer from outside the NRC.
23 MR. MCINTYRE: It would not be transparent.
24 MR. WALLACE: How much effort would it be to 25 figure out if this is adequate, for someone who wanted to
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149 1 know and who was reasonably intelligent and had the 2 background?
( Not just taking the word of the NRC staff.
3 MR. KEMPER: Focusing on the large break, we 4 recently published the CQD with all of the questions and 5 answers, which is eight volumes.
6 MR. WALLACE: Is that all words or is there 7 analysis?
l 8 MR. KEMPER: Test simulations are included and l I
9 correlations.
10 MR. WALLACE: Obviously, this committee can't do 11 that and that's what bothers me.
12 DR. KRESR: Graham, we've had about a dozen or l l
13 more --
14 MR. WALLACE: You've been around all this.
s 15 DR. KRESR: -- subcommittee meetings on thermal 16 hydraulics and these are exactly the kind of questions we 17 were asking.
18 MR. KEMPER: So for large break, we're using 19 WCOBRA/ TRAC methodology and WCAP-14171 speaks to the AP600 20 application. We've really -- this is a bit simplified in 21 that --
22 MR. CATTON: What's the WCAP number for the 23 WCOBRA/ TRAC best estimate code itself?
24 MR. KEMPER: 12945. ,
i 25 MR. CATTON: 12945. Are you going to send me a l
l
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l 150 )
i i copy? I worked very hard to get it.
f
'(t 2 MR. KEMPER: You mean our recently published eight 3 volumes?
4 MR. CATTON: Yes. I think I deserve it. You 5 might explain the transition. What size breaks delineates 1
6 small from large?
7 MR. KEMPER: Large-break LOCA begins with the 8 double-ended cold leg by guillotine break and we actually l 9 did have REI from the staff on this asking us to be sure 10 that we completed the spectrum.
)
11 So for AP600, we ran WCOBRA/ TRAC down to a 12-inch 12 equivalent diameter break and that would be the --
13 MR. WALLACE: That's not reported on this.
14 MR. KEMPER: That would be reported in this WCAP
(~)
(_j 15 as a response to an REI.
16 MR. WALLACE: You filled in to the continuity 17 between the double-end guillotine break of a cold leg and a 18 ten-inch break, which is called small break. There is some 19 sort of continuity between them. There is not just a huge 20 gap between the enormous one and the small one.
l i
21 MR. KEMPER: That's right. Now, the SSAR itself I
22 goes down to a .6. 1 23 MR. WALLACE: But it doesn't give anything between 24 ten inch and double-end cold leg.
25 MR. KEMPER: It does give a .6 split.
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i 151 1 MR. WALLACE: That's right. You're right.
() 2 MR. KEMPER: It's 1.5 square feet, maybe.
3 MR. WALLACE: See, the trend with small breaks is 4 .
going to get worse as the break gets bigger. Then suddenly 5 there's a gap and you say large breaks are okay. It's not
- 6 clear that the minimum situation is being found.
7 MR. KEMPER: And perhaps that is what led the 8 staff to ask for more. So we did do a couple other break 9 sizes to narrow the gap.
10 MR. WALLACE: Why does the large break curve in 11 here stop at 120 seconds?
l l ,
12 MR. KEMPER: Because the core is quenched at that i 13 point.
14 MR. WALLACE: None of the other ones stopped. I 15 mean, things keep going on after that, don't they?
16 MR. KEMPER: Yes, they do. And now you're in a 17 post-quench situation.
18 MR. WALLACE: But it's still hot and it's still 19 generating steam and losing mass and all sorts of thingo 20 going on.
21 MR. KEMPER: Well, if you look at Chapter -- it's i
22 actually under 15, subsection under 15 (c) , there is a '
23 large-break carried on out until --
24 MR. WALLACE: There is something that I missed?
25 MR. KEMPER: Yes.
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152 1 MR. MCINTYRE: Long-term cooling.
() 2 MR. KEMPER: It's actually presented in the 3 long-term.
4 MR. WALLACE: It's a big jump to long term from 5 120 seconds.
6 MR. KEMPER: And that gap is covered by this 7 analysis, which is presented under one of the sub -- !
l' 8 15 (c) (1) -- 15. 6. 5.4 (c) (1) , I believe it is. So that case 9 was analyzed. 1 i
10 MR. CATTON: Do you.do a calculation at 12 inches 11 with NOTRUMP or do you make sure thc; as you reduce the 12 break size with COBRA / TRAC, that there is one value of break
! 13 size that's done with both codes?
i 14 MR. KEMPER: No, we have not done that. We have
!- 15 done 12-inch with COBRA / TRAC, ten-inch with the NOTRUMP i
l 16 code.
l 17 MR. CATTON: Are things continued as you go from 18 the 12-inch to the ten-inch with NOTRUMP?
19 MR. KEMPER: They're comparable. The
( 20 1.0-something square foot break, WCOBRA-TRAC had a peak clad ;
l j 21 temperature of between 800 and 900 degrees. That was also
)
l 22 .true for the 12-inch break with COBRA / TRAC and in the SSAR l 23 section, the ten-inch break was again in that range.
1 24 MR. WALLACE: In ten-inch, your emphasis seems to I 25 be on minimum inventory, which doesn't appear in large ANN RILEY & ASSOCIATES, LTD. ;
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153 1 break. So there's a metric which is only used for small n
2 breaks.
3 MR. KEMPER: That's the metric that we're --
4 MR. WALLACE: It's getting worse as the break gets 5 bigger. So where does it go?
6 MR. KEMPER: Well, you would have -- if you get to l 7 a large break, you're really going to blow about all the 8 inventory out anyway.
9 MR. WALLACE: But there must be some minimum.
10 Minimized is bad word, but minimum is understandable.
11 DR. SEALE: I'm glad you cleared that up. l 12 MR. WALLACE: I think it would be useful if there 13 could be this transition made to fill in the space between 14 large break and small break, so that we know with some
' r~N k ,) 15 reassurance that it's continuous. There isn't something 16 missing there, say a 12-and-a-quarter-inch break or 17 something is the worst.
18 MR. KEMPER: Well, they are very non-limiting 19 relative to the double-ended cold leg guillotine and I would 20 opine that the double-ended guillotine is the minimum 21 inventory of all.
(
22 MR. WALLACE: Because it's cleared out.
l 23 MR. KEMPER: Because you literally take everything l 24 out of the system.
25 MR. WALLACE: So why do you bother about minimum ANN RILEY & ASSOCIATES, LTD.
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i 154 1 anyway? It'seems to be such'an important metric for some of
() 2 these other breaks.
3 MR. KEMPER: In the small break, you're trying to 4 -- there is a criterion on the URD that for breaks up to, I 5 believe, six inches, you should not have core uncovery.
6 MR. WALLACE: There is also.a history of core
( 7 uncovery happening.
i 8 MR. KEMPER: Not on this plant.
9 MR. WALLACE: At least one plant that I know 10' about.
! 11 MR MCINTYRE: And those are some of the reasons 12 we've changed the design of the plant. We've taken out the 13 loop seals and done some things like that. I think the 14 reason we look at minimum inventory for small break is to
() .15 ' show that -- that that's important for keeping the core 16 covered.
l 17 MR. WALLACE: The problem is, for the reader, you l
18 have the conclusion which says that the minimum inventory 19 gets lower and lower as you go to bigger and bigger small 20 breaks and there is nothing that connects that to the large s 21 break analysis, and so it turns around somewhere or i
22 something happens. Makes it not a consideration with an 23 11-inch break or a 13-inch, whatever.
i 24 That might be worth filling in that.
25 MR. KEMPER: I think I understand your point. The ANN RILEY & ASSOCIATES, LTD.
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155 1 small break is done with the NOTRUMP code and there is a bit
() 2 different flavor to that because it's a traditional Appendix 3 K evaluation model.
4 MR. CATTON: But the code that was approved by NRC 5 in 1985 is not the code that's on the table today.
6 MR. KEMPER: That's correct. There were many 7 changes made.
8 MR. CATTON: And what you say there implies that 9 it is.
10 MR. WALLACE: No , it's just a statement.
11 MR. MCINTYRE: It's a statement of fact.
12 MR. KEMPER: It's a statement of the origin of 13 NOTRUMP, if you will, which was, at'that time, NOTRUMP was 14 begun.
) 15 MR. CATTON: You might have said a version was 16 ' approved by NRC, would have been more correct.
17 MR. KEMPER: Yes, that's true. And what Dr.
18 Catton's really referring to is there were a number of 19 changes made to improve NOTRUMP for the AP600 situation.
20 MR. CATTON: And still some open questions.
21 MR. KEMPER: And we have recently responded to 22 some outstanding items on that.
23 DR. FONTANA: Backing up a bit, what is CQD l 24 methodology? '
25 MR. KEMPER: Code qualification document. That's i
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156 1 the WCAP-12945 that I mentioned before. Ultimately, then A
! ! 2 the plant would go to a long-term cooling situation. We V
3 have developed WCOBRA/ TRAC to do that situation with a 4 simplified nodalization from the detail that's used for 5 large break.
6 DR. FONTANA: With respect to that window 7 calculation, talking about these windows in time, in a 8 subcommittee meeting, I got the impression that we weren't 9 all that happy with that. Have you done any more since then 10 to try to see how to connect those windows analytically?
11 DR. KRESR: I think our subcommittee conclusion or 12 finding was that it was a hard way to do it, but technically 13 it's okay. Is that what we came up with?
14 MR. CATTON: There were a few things that could be A
( ,) 15 done to further demonstrate that it's a good -- not a good 16 way to do business, but a reasonable way. Acceptable is the 17 word. One of the concerns was the -- you know, you set 18 boundary conditions for the problem. You ought to change 19 the initial conditions around a little bit and see if it 20 evolves to the same place. If it does, then you can make 21 arguments about its usefulness.
22 At this point, to my knowledge, you have not done 23 that.
24 MR. KEMPER: This WCAP-14776 --
25 MR. CATTON: If that's the document I have, it
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157 1 doesn't do it.
() 2 MR. KEMPER: .There are simulations in there that 3 consider burying the initial conditions and showing that the 4 simulation reaches the same ultimate steady state.
5 MR. WALLACE; The test data are ,from APEX?
6 MR. KEMPER: The test data is from the OSU 7 facility. In fact, it would probably be worth going to the 8 next slide to highlight that. The validation that was done 9 for these codes. From the test facility, COBRA / TRAC had a 10 large number of tests done for its application to a three 11 and four-loop plant for AP600, We included simulations of 12 the core makeup tank test facility, which provided data on
)
13 behavior of the core makeup tanks to validate the code for 14 that use.
15 Also, with direct vessel injection, this is
~16 different geometry than what was done in any of the three 17 and four-loop plants, so CCTF-58 and UPTF test 21 were done l 18 to demonstrate the capability of the code to do direct 19 vessel injection modeling for core reflood.
20 MR. CARROLL: What are those acronyms?
21 MR. CATTON: CCTF is the cylindrical core test 22 facility. That was the Japanese contribution to the 3D 23 program. UPTF is the upper plenum test facility, which was 24 the German contribution.
25 MR. KEMPER: For NOTRUMP, there was a need to do O ANN RILEY & ASSOCIATES, LTD.
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158 1 significantly more and included in the validation were
( ) 2 separate effects tests, again, from the core makeup tank 3 test facility that Westinghouse had. For ADS Stages I 4 through III, there is the Vapore facility in Italy which is 5 a full-scale simulation of the ADS valve configurations and 6 sparger. So NOTRUMP was benchmarked against that.
7 Also, single effect tests for level swell and core 8 uncovery were modeled with NOTRUMP.
9 So with that as background, then we went on to 10 look at the AP600 specific integral test data and validate 11 NOTRUMP against that.
12 MR. WALLACE: How did you validate? Did you 13 validate the way that INEL validated it, where someone 14 looked at it and said that looks good and this doesn't-look
) 15 so good? All the vague comparisons. How do you decide the 16 code has done a good enough job on some data?
17 MR. KEMPER: Well, stepping back a step, what 18 you're really looking at is the highly ranked items from the 19 PIRT to identify what the important phenomenon are and then 20 run the code against a reasonable or properly scaled 21 facility and compare the results.
22 MR. WALLACE: It's not always so easy. Sometimes 1
23 a small change in the scenario will result in CMT draining 24 or not draining at certain times and the whole thing looks 25 very different. Yet, you still are asked to make a b
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159 1 comparison, I don't think it's an easy thing to do. Maybe
() 2 the staff knows how to evaluate these comparisons.
3 MR. MCINTYRE: There were a set of guidelines, and 4 I can't remember what they were, but when we said the l
5 comparison was good, that it had certain characteristics, !
6 when it was outstanding, it had blinds right on, when it was 7 absolutely awful.
8 DR. KRESR: Yes. This had to do with estimated I
- 9 uncertainties in the data and whether or not -- and 10 estimated uncertainties in the code. And when you compared 11 the two over the full range of the transient, if none of the 12 data in the code fell outside a certain level, you had one 13 criteria for good, a
- 1d then if a certain amount of the data
-14 fell outside, you had another criteria for moderate, and
( 15 -then one for poor, I think.
16 MR. MCINTYRE: But it was very qualitative.
17 DR. KRESR: Yes. It was very qualitative, but it 18 had qualitative aspects, because it did involve the 19 uncertainty.
20 MR. WALLACE: Isn't it true, once the ADS IV 21 opens, it doesn't really matter what happened before, 22 everything is fine?
23 MR. KEMPER: Well, that's a topic that we're 24 discussing in the T&A subcommittee at this point.
25 MR. WALLACE: That would be a mucn more useful !
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160 l' card.to play than all this.
l
() 2 MR. CATTON: But they're having a little problem 3 with that. They've got two ways the seam can 90. One is 4 out through the pressurizer and the other is through the ADS 5 IV and depending where more or less flow resistance is.
l 6- found, you get different results, and that's when the j 7 minimum core level occurs. So it's a problem and part of l 8 it's the modeling.
L 9 MR. MCINTYRE: And we'll talk about that in May.
1 10 MR. CATTON: RELAP-5 couldn't address that either.
I
'll MR. WALLACE: It is sensitive to the model.
12 MR. CATTON: Absolutely. And right now the models l
13 are physically incorrect. So whatever you do, you have to
- 14 .make arguments as to why it doesn't matter. What
) 15 Westinghouse chose to do was to take a penalty on the level. j i
16 The question then became how do you know what the 17 penalty should be, big, little, a lot, two feet, three feet, L 18 what do you do, and what basis do you have for doing it.
l 19 MR. WALLACE: What I'm hearing is that ADS IV l
20 opening doesn't overwhelm everything else and everything is 21 ' perfect. You do have to these complicated balances. Is 22 that true or is he --
23 MR. .KEMPER: That's correct. You need to have, j 24 let's say, an appropriate calculation to carry it through --
25 - carry the small break through the point where you have the ANN RILEY & ASSOCIATES, LTD. .
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l 161 1 stable continuous IRWST injection. And at that point is
( 2 when the long-term cooling phase would begin with injection 3 from the IRWST through the DVI line and venting through, l 4 primarily, at that point, ADS Stage IV.
5 The Oregon State facility, which we also used for 6 NOTRUMP validation, ran a number of cases, very long, into
- 7 1cng-term cooling and provided the basis for the long-term 8 cooling validation.
9 MR. CARROLL: A number of years ago, I l 10 participated with the rest of the committee in a great
, 11' debate over ROSA. Why don't I see any reference to ROSA i
12 here?
13 MR. MCINTYRE: Those are tests that were run by l
14 the staff as confirmatory and they looked at different 15 things on a different scale.
1 i 16 MR. CARROLL: And what did all that prove?
17 MR. CARUSO: Those experiments were not done by
! 18 Westinghouse and they were not --
l 19 MR. CARROLL: I understand.
I
- 20. MR. CARUSO: They are not used by Westinghouse to l
21 make the licensing case.
22 MR. WALLACE: But this is a question I hope we can i 23 get to the staff, where the staff ran tests and the staff 24' did analyses. How did they work out compared with all this 25 stuff? I hope we can spend some time cx1 that, because what l
1
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1 162 1 I've seen from the staff simply seems to say that the method
(~%I 2
- .%J used to Westinghouse to analyze has our approval or it 3 doesn't or whatever.
4 There is no comparison with your own tests and 5 analyses anywhere.
6 MR. CARUSO: The staff did its own calculations of 7 a large number of different scenarios, for a number of 8 different reasons, both for Chapter 15 analyses, for PRA 9 calculations, and for a number of other reasons. i 1
10 And the results were not significantly different 11 from the results that Westinghouse produced for those 12 scenarios.
13 MR. WALLACE: Is there any place where we get to 14 see that, where you actually ran the same thing which we
( ,) 15 find in the document here, which we can compare 16 Westinghouse's predictions with yours?
17 MR. CARUSO: Unfortunately, no.
18 MR. CATTON: Why?
19 MR. CARUSO: Because those calculations do not 20 form the basis for the staff approval. The basis for the 21 staff approval is the calculations that are presented by 22 Westinghouse.
23 MR. WALLACE: So why do you do them at all?
24 DR. KRESR: To be a paper document and all of that 25 and there were some issues of proprietary information and we
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l 1
163 1 -- I think the conclusion was that it was too revealing of (f 2 proprietary information for the paper and anything NRC 3 produces essentially goes to the public and gets released.
4 So I think that data is here and you can use it to 5 form -- help form their judgments and their opinion, and 6 we've seen the data. It's been presented to our 7 subcommittee. And pretty much it does confirm the results 8 of the Westinghouse tests to a large extent. But I don't ,
9 think we'll see the stuff written up in a decision because 10 of this issue of confirmatory -- of proprietary data. j 11 MR. WALLACE: When we look at something like this, I 12 1676 degrees Fahrenheit predicted by Westinghouse. What 13 does the staff predict?
14 MR. MCINTYRE: Tom, would that have been in the rh
(,) 15 meeting you had last year?
16 DR. KRESR: Yes.
17 MR. MCINTYRE: The thermal hydraulic subcommittee.
18 MR. WALLACE: Do you have a corresponding number 19 from the staff?
20 DR. KRESR: Yes. There is. The staff did take a 21 couple -- several of the test that were run by Westinghouse I 22 and they did their own --
23 MR. WALLACE: I'm talking about AP600 predictions.
24 DR. KRESR: Yes. They did their own predictions 25 for the test and then they did their own predictions for
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164 1 AP600. And best I remember seeing the data, they weren't 2 exactly the same, but they confirmed that they were close, 3 very close to the same numbers. ;
4 MR. POWERDR. SEALE: I think what they actually
'5 confirmed is they were below the design.
6 DR. KRESR: That's right.
7 MR. POWERDR. SEALE: There was 100 degrees
! 8 difference.
i' 9 DR. KRESR: That's right.
10 MR. CATTON: The concern is not here with the 1676 11 because that's a large break. For a large break, the plant -
12 pretty much acts like any plant that we have and they've 13 been beaten to death experimentally everywhere, different L
14 scales, all sorts of things. l 15 Where the problem comes in is when you start 16 looking at the small break and you go over to the 17 Westinghouse use of NOTRUMP and the staff use of RELAP-5. i 18 Some of the modeling is just inappropriate for what they're 19 trying to model. I mean, homogeneous, one-dimensional flow, 20 when it's stratified, these kinds of things.
21 So with RELAP-5 they ran into a judgment problem 22 as well. They had to say something about the results they 23 were getting.
24 When you take a look at everything in front of you 25 in total, you finally -- you sort of get a good feeling, l ANN RILEY & ASSOCIATES, LTD.
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165 1 yeah, it's probably all right. But has anybody really shown
( ~g) 2 it? No. And that's kind of where you're at. It's only 3 when you see all the data on the table you can conclude, 4 well, you know, it's going to be really hard not to get this 5 thing filled up with water.
6 But the codes aren't able to do the calculations.
7 DR. KRESR: But the various tests were sure 8 revealing in that respect.
9 DR. FONTANA: How do you document in one place 10 that this --
11 MR. CATTON: A lot of this is documented in the 12 report by Banergy, where he walked through the -- one of the 13 questions that was raised early on with this whole business r
14 was do you have enough data that if you use your code to I
15 predict all of these results and you compare, well, you can 16 say, I have enough, I'm finished.
17 So that particular question was addressed by the 18 staff -- by staff, I mean research, not the people here. In 19 order to be able to say something about RELAP-5, and they 20 did it and they compared it. Two rather nice reports, they 21 said, yeah, the data is sufficient, but it included a lot of 22 ROSA, OSU, SPES, separate effects tests, the whole package.
23 When you had it on the table, you had enough to 24 come to a conclusion based on the data by itself.
25 MR. CARROLL: To the extent you have looked at I~h ANN RILEY & ASSOCIATES, LTD.
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166 1 this in the thermal hydraulics subcommittee, what conclusion
(
wi
) 2 do we have as to the role ROSA played? I'm curious as to 3 whether it was worth doing it in ROSA.
4 MR. CATTON: You know my feelings on that, Jay. I 5 went to the Commission to try to stop it and I wasn't able 6 to.
7 DR. KRESR: I think the feeling of the 8 subcommittee as a whole was that it was very useful. They 9 got value for their money, a lot of good information for the 10 cost, and it was very useful in filling in gaps that existed 11 in some of the test data and in answering specific questions 12 that weren't exactly answered by other tests.
13 I think on the whole it turned out to be -- our 14 earlier objection to that test was that it was being done l' s (j.
15 overseas and we were going to lose expertise over here.
16 That was one of them. And it wasn't exactly a good 17 simulation of the AP600 and we had a number of objections, 18 but it turned out to be a pretty good set of tests.
19 MR. CARROLL: Okay. Just curious.
20 MR. KEMPER: To quickly highlight the results of 21 the analysis in Chapter 15. As noted, the calculated PCT 22 for the limiting guillotine, cold leg guillotine break is at 23 the 95th percentile using the best estimate methodology, ;
24 1676 degrees Fahrenheit.
25 For small break LOCAs up through the largest pipe
[\-
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i 167 1 size of the passive safety system, there is no core uncovery l() 2 predicted, so there is no cladding heatup associated with 3 these transients.
4 And the staged depressurization of the RCS and the 5 results of the Chapter 15 analyses indicate that the system 6 is effective and you reach IRWST stable injection. I 7 Also, there are cases for long-term cooling which 8 show that during the IRWST injection and then ultimately in 9 containment recirculation, that you have continued and l
10 effective core cooling.
11 This is the reference case for the WCOBRA/ TRAC 12 AP600 large break case. The various core locations are 13 indicated on the legend at the right. Hot rod is the 14 hottest rod in the core. It's located within the hot
) 15 assembly, which is modeled as being at the hottest value
! 16 permissible within the core.
17 Average power rods in the methodology are located '
l 18 at two locations, one of which is beneath an open hole 19 location in the upper core plate. Another is underneath a 20 guide tube location in the upper core plate.
21 Finally, rods that are on the periphery of the 22 core are in the designed low power. So, in fact, they --
23 you can't really see it here, they do have a little bit of 24 an initial heatup.
25 They are, almost from the start of blow-down, O ANN RILEY & ASSOCIATES, LTD.
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168 1 effectively cooled at that location.
() 2 3 phase.
So the peak that occurs during the blow-down l
I 4 MR. WALLACE: That's DNB, that first one, isn't 5 it?
6 MR. KEMPER: Yes, I suspect it is. You're just --
7 your core has to -- you have to go through a zero flow point 8 to reverse the flow to feed the cold 1 . break. This 9 behavior is considerably better than your typical operating 10 plant and it's a consequence of the low power density and 11 also the ability of the AP600 to, within the' blow-down 12 phase, actually provide effective cooling to the average 13 powered rods within the core.
14 That enables the reflood to proceed in a better
) 15 fashion than is typically true for a PWR. So that the 16 reflood peak cladding temperature actually is lower than the 17 blow-down cladding temperature.
18 DR. KRESR: What is the regulatory requirement on 19 peak clad temperature?
20 MR. KEMPER: 2200 degrees Fahrenheit, which is 21 about 1200 degrees C, which would be about 1470 degrees K.
22 DR. KRESR: Are there any regulatory requirements 23 on the margin you need to maintain between your value and 24 that value or is that zero permissible?
25 MR. KEMPER: In an evaluation model analysis, it's i
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I 169 1 always been you had to just meet the 2200 degrees.
I( ) 2 DR. KRESR: At 95 percent.
3 MR. KEMPER: That's with the regimen that Appendix l 4 K imposes on you. Under the BE methodology, the 20-20 in 5 the three-loop, it still must be met. I am not sure that 6 it's really been established if what if any degree or margin
- 7 the staff might be looking for there.
8 But certainly it's large here.
! 9 DR. KRESR: I'm asking this question not because 10 of AP600, obviously, but when we get around to evaluating 11 power upgrade requests, I'm wondering --
12 MR. CATTON: When you sit there with the peak clad l 13 temperature at 1600-and-some-odd degrees, you've got a lot l
14 of room to move, maybe up 20 or 30 percent
) 15 MR. WALLACE: The first peak is D&B related, so 16 your accuracy of prediction depends on some sort of D&B l
17 correlations. The second peak is reflood governed, isn't 18 it?
19 MR. KEMPER: Yes.
l 20 MR. WALLACE: 1.nd I understand that the NRC is i
21 doing research on reflood because the present methods in 22 their codes are, for some reason, suspect or are not as good l 23 as they should be. Are your codes free of that sort of 24 defect?
25 I have the question. I don't know if you can i
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1 t
170 1: answer it. It concerns me that the NRC was telling us they l () 2 had to do research on reflood because the methods were so 3 lousy and you're -- you've got some method which is not 4 subject to these deficiencies, perhaps.
5 MR. MCINTYRE: We are not aware of any problems 6 with our methods.
7 MR. KEMPER: And they were heavily benchmarked 8 against the 2D3D reflood programs.
9 MR. WALLACE: So the deficiency is somewhere in 10 the agency.
11 MR. MCINTYRE: You would have to talk to the staff 12 about that.
13 MR. CATTON: It was when they tried to make the 14 modeling better. They found out all kinds of defects and
) 15 what they did is they made a model that was far more 16 complicated than the database and the new model doesn't work 17 very well.
l 18 So rather than go back to a simple model that does l
l 19 a pretty good job compared to a wide variety of data, they 20 decided to make more measurements.
21' MR. WALLACE: So there might be some time in the 22 future when, as a result of the new work, someone might want 23 to revisit this reflood prediction. Not perhaps for AP600, 24 but in some other context.
l 25 MR. CATTON: There's all kinds of reflood data.
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171
-1 There are facilities in Europe, there's two in Japan.
() 2 There's i Pinds of data. I'm not sure they need to do f 3 that.
! 4 MR. WALLACE: But what we've heard from the staff I
- 5 indicated that it's quite possible to develop lousy physical 1
6 models.
! 7 MR. KEMPER: They did put them in a code.
8 MR. CATTON: They have a lousy physical model.
9 They could go back to the previous one, which was okay.
1 10 MR. WALLACE: This is the previous one. This is 11 closer to --
l 12 MR. CATTON: The kind of reflood model you have is 13 closer to the previous one.
14 MR. MCINTYRE: I would say that's correct.
15 MR. CATTON: What I said is correct, right?
16 MR. MCINTYRE: That our model is probably closer 17 to the previous one, yes.
18 MR WALLACE: This is really based on more or less 19 full-scale tests on reflood with assemblies for full-scale.
20 MR. CATTON: And they do. The SCTF was full 21 height and was a section all the way through.
22 MR. WALLACE: No matter what the rationale, if i
23 it's the real data and it's full-scale.
24 MR. CATTON: It's probably all right.
25 MR. KEMPER: Okay. This is a couple of the liquid i i
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172 l 1 levels from the transient. This may address Dr. Wallace's
()
t 2 earlier question about inventory. This is for the lower 3 plenum and the: DECAL break LOCA. At about 20 seconds here, l I
4 your collapsed level is about one foot and the rest of the 5 system is basically void. So this would be_indeed the 6 minimum --
I 7- MR. WALLACE: The important. thing is how long you j i
8 stay there. If you stayed there too long, you'd be in real 9 trouble.
10 MR. KEMPER: Right. And this is where the )
11 accumulators come on, you can see the level there in the l
12 lower plenum builds up.
13 MR. WALLACE: So there probably is a continuum..
14 If you go to continue -- the minimum clad level versus break
) 15 size, it probably does fit in with the small break, if you I 16 go to all possible break sizes. The thing is that with the 17 large break, you stay there for such a short time that it 18 doesn't matter. So you have to relate not just level, but
! 19 how long you stay there. That's a measure of --
l l 20 MR. KEMPER: We do have 20 seconds roughly or 21 pretty much in adiabatic heatup condition for the plant, 22 until you are able to refill the lower plenum, and then have 23 the replenishment of liquid within the assembly.
24 MR. MCINTYRE: Levae that up for a second, because 25- I think this helps answer Dr. Wallace's question from l O ANN RILEY & ASSOCIATES, LTD.
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173 1 earlier of how do we size these tanks. The answer is one of
() 2 3
the ways is by running sensitivity studies like this and showing that the accumulator is -- that the job it has to do 4 is to refill the lower plenum, so you run a series of breaks 5 and do studies and then show that indeed you picked the 6 right point pressure and volume for the accumulator to go 7 back and refill the lower plenum for this range.
8 MR. WALLACE: So the accumulators are really 9 designed to handle the large-break LOCA.
10 MR. MCINTYRE: To refill the lower plenum on a 11 large break LOCA, yes. Very, very specific and that's the 12 material we'll talk about.
13 MR. KEMPER: So that's a quick look at large 14 break. This is intended to give you a feel for the nature O(_,/ 15 of a typical small break LOCA transient. This is one case 16 out of a SSAR, two-inch cold leg break case, and what you 17 have here is the reactor coolant system inventory versus 18 time.
i 19 And very early on, within the first 30 or 40 20 seconds, you would trip the reactor and actuate the F signal 21 based on pressurizer pressure. Then initially the CMTs 22 would be in the recirculation mode I mentioned before.
23 Eventually, you get to the point where the CMTs begin to 24 drain.
25 And at this point, the CMTs -- the flow rate
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174 l
1 increases because you're able to drain it and replenish the
(-s) 2 pressure with steam from the cold leg.
3 The break flow now is reduced, too, since the cold l 4 leg is pretty much void, so you see an increase in the l 5 inventory.
l 6 When the CMT reaches the set point for ADS Stage 7 I, it comes on. The depressurization at ADS I and then 8 Stages II and III affect, cause the accumulators to come on, l 9 with the accumulator injection, the inventory goes back up 10 to close to 250,000 pounds.
11 Then they are spent and the transient continues on 12 down to, as the CMTs continue to inject, and eventually the l 13 CMTs reach the set point for ADS Stage IV. That comes on 14 and before too long, the CMTs have emptied.
() 15 You are now where the ADS stage is primarily ADS 16 IV are involved in depressurizing the system to the point 17 the IRWST can come on based on its available liquid 18 containment pressure. At this point, the IRWST comes on and 19 by 5,000 seconds it's in a stable injection mode.
20 So this is how these systems actuate and play out 21 in the context of a typical small break event.
22 MR. CATTON: Graham, this balance that we were 23 talking about before between ADS IV and the pressurizer is 24 right where it says IRWST on, which is the minimum level, 25 which is why it's a concern. In order to predict OSU, they l
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175 l- 1 adjust the level in the pressurizer to get the balance right 2 and then there is a question, well, okay, if you do that, 3 how are you going to extrapolate that to the full size, what 4 do you do with it.
5 This is where the issues came up and this is where 1
6 the codes, and this includes RELAP-5, are weak in that they l 7 can't deal with that kind of a problem.
l 8 DR. WALLIS: So what do we conclude, however?
9 MR. CATTON: On this?
10 DR. WALLIS: From what.you just said.
j 11 MR. CATTON: That maybe you'll have to decide 12 based on judgment alone. Unless they fix.the code.
13 DR. WALLIS: I like to have some reason for basing 14 a judgment.
l 15 MR. CATTON: The reason can be pouring over all of l 16 the experimental data that's available, which is what some l'/ of us did in trying to evaluate RELAP-5. Then you become 18 convinced that this thing is sort of like a coffee pot and 19 it's got this bubbler down in the bottom.
20 DR. WALLIS: You're not trying to reach judgment
, 21 on a coffee pot, i
22 MR. CATTON: You have enough water to keep the 23 bubbler covered.
~ 24 DR. SEALE: That's really the thing. There's 25 plenty of water there all the time.
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176 l
1 MR. CATTON: I didn't say there wasn't.
'O( j 2 DR. WALLIS: So your levels, your minimum levels 3 that we see in this IRWST on, are in none of the 4 calculations in this SSAR or anything like as dramatic as in 5 some of the results that we saw two years ago or something 6 with the experimental data or predictions which went to much 7 lower values.
8 This is a much milder, much safer-looking 9 transients than --
10 MR. CATTON: I bet this transient was calculated 11 based on that extrapolated adjusted level.
j 12 MR. KEMPER: This does include the level penalty.
13 MR. CATTON: So what they've done is they've tuned 14 this a bit already.
- (/~T
,/ 15 MR. KEMPER: Yes.
16 MR. CATTON: They tune it to the OSU data and then 17 just multiply it by the scale factor.
i 18 MR. KEMPER: Okay. So as regards the LOCA portion i 19 of Chapter 15, we've looked at DELCG and other breaks, the 20 DELCG break being limiting, and find that the AP600 passed 21 the safeguard systems, which are all that are credited in l
22 this, are effective and doing what they need to do to 23 provide safety injection water and allow stable long-term 24 cooling of the plant.
25 The ECCS performance meets the requirements that
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i 177 !
1 it needs to under 10 CFR 50.46. One important thing, I I
() 2 think, is that for both large break and cold leg break, j 3 these are -- these results are quite favorable relative to j 4 the limits than what a current PWR would predict for either l
5 large break or small break.
6 DR. FONTANA: The long-term heat removal depends 7 on the containment. When are we going to discuss the l
containment behavior?
8 9 MR. KEMPER: Chapter 6 contains that.
10 MR. MCINTYRE: That's in May. It's scheduled for l 11 May.
12 CHAIRMAN BARTON: There is a six-month schedule.
13 MR. CATTON: Is that Mr. Schultz?
14 MR. MCINTYRE: No , that is not Mr. Schultz. I
) 15 believe that's the May schedule.
16 DR. WALLIS: Now, you've excluded what you call ,
17 four process errors and operator actions in all of this.
l 18 MR. KEMPER: Yes. For any of these events, it's l
19 the passive safety systems alone.
.20 DR. WALLIS: I think it's highly likely that what 21 you say here is correct. The most likely way in which this 22 could be screwed up would be by some human action. We talk 23 about that some other time.
25' MR. MCINTYRE: Yes.
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178 1 DR. WALLIS: And that is something we get into --
() 2 MR. MCINTYRE: When we discuss the PRI.
3 DR. WALLIS: So analysis has been made of ways in
'4 which humans could inadvertently get the system on the wrong 5 path.
6 MR. MCINTYRE: Yes. Well, the system could be on 7 the wrong path and humans could fuss with it.
8 DR. WALLIE: And make it worse, j 9 MR. MCINTYRE: Sins of omission and sins of l
10 commission type things, yes.
t l 11 DR. KRESR: Chapter 15 contains a couple of l 12 appendices that deal with radiological consequences. Are we 13 going to hear that as part of the Chapter 15? ,
14 MR. MCINTYRE: Yes.
! 15 DR. WALLIS: Are we going to hear about ejection i
16 of control rods?
17 MR. MCINTYRE: Yes.
l 18 MR. KEMPER: Not from me, though. j 1
l 19 MR. MCINTYRE: I said we have three presentations, 20 LOCA, non-LOCA, and we just finished the first. J 21 Before we go on, I think there was question 22 earlier when we were talking about what the limits are on l 23 these analyses and I think Dr. Catton made the comment that, 24 gee, if it's 1576, that there's a lot of room to play around 25 between that and 2200 degrees.
I ,
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179 1 The staff has had some limitations and some
() 2 3
restrictions on the use of the codes, in that case for large break LOCA, and I can't remember what the number is, I think 4 it's like 1750 degrees or something like that in the 5 documentation. So that we understand --
6 MR. CATTON: So the certification will have a 7 statement.
8 MR. MCINTYRE: The certification doesn't, but the l
9 code documentation does. It makes more sense to put it i
10 there because the certification is what it is and it's going 11 to have 1676 degrees in it. But if you go to use that code j 12 for something else with the code documentation, there is the I
13 restriction of the 1750 degrees.
l 14 MR. KEMPER: It's 1725, actually,
) 15 MR. LOIDR. SEALE: 1725. This is Lambrcsc Lois.
16 The analysis showed that Westinghouse was convinced and so l
l 17 was the staff that the maximum would be in the neighborhood 18 of below, slightly below 1700. So they accepted the limit i
19 of 1725 and that's also relative to the question as to l 1 l 20 whether that makes limits. l l
21 MR. CATTON: That's tied to the Westinghouse
- 22 COBRA / TRAC code as it is today.
L 23 MR. LOIDR. SEALE: Yes. WCOBRA/ TRAC, after it's 24 . applied to AP600. l 25 MR. CATTON: Okay.
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180 1 CHAIRMAN BARTON: Any other questions of Robert at 2 this time?
i 3 MR. CARROLL: While all of this wonderful stuff is 4 going on, the operator does have the option of trying to 5 operate some other systems for non-safety reasons. What 6 does that do to all of this? Does that in any way make 7 things worse or can it make things worse?-
8 MR. KEMPER: That was covered in the rest program.
9 In the SPES facility, there was a test run where the 10 charging pump, the startup feedwater was actuated and it was 11 less limiting as expected when those non-safety systems did 12 actually --
13 MR. CARROLL: I always expected a large break LOCA 14 was going to be the limiting accident for quite a long time.
( 15 So that's why I asked the question.
16 MR. MCINTYRE: And we also did a WCAP report that ,
i 17 looked at adverse systems interaction, that what happens if I
L 18 somebody turns something on or turns something off. And the l 19 normal systems that are excluded from Bob's analysis, 20 because he assumes that he has a loss of off-site power at 21 the same time.
22 MR. CARROLL: And everything looked good in that 23 regard.
'2 4 - MR. MCINTYRE: Yes.
l 25 MR. CARROLL: And the staff agrees with that? Did i
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l 181 !
1 the staff look at that in-depth?
!A
- ' )i
( 2 MR. CARUSO: Yes. The staff considered adverse 3 systems interactions and has accepted Westinghouse's report
! 4 on that.
5 MR. CARROLL: Okay.
j 6 CHAIRMAN BARTON: Any other questions?
)
7 DR. UHRIG: The 1725 limit, is this also 8 applicable to other standardized plans?
9 MR. LOIDR. SEALE: No. This is only for AP600.
10 DR. UHRIG: Because of the novel features?
11 MR. LOIDR. SEALE: Because of the ultimate 12 analyses.
13 MR. CARUSO: One of the factors that went into 14 determining the 1725 limit was hydrogen generation. For (3
() 15 AP600, WCOBRA/ TRAC does not treat metal / water reaction and 16 we felt that as long as we kept the temperature below the 17 point at which the metal / water reaction would start to 18 become significant, that we could accept the code.
19 But if the temperature starts getting up above 20 that into that range, which we have not evaluated the code 21 in AP600, we have determined we would have to re-review it 22 for that particular -- at least that particular phenomena.
23 CHAIRMAN BARTON: Thank you.
24 DR. KRESR: The metal / water reaction is generally 25 thought to start getting significant around 1800, right?
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i 182 1 MR. CARUSO: Yes. This 1725 gave us a certain
() 2 margin.
3 MR. CARROLL: And the concern there is the energy 4 that it's inputting or the hydrogen or both?
5 MR. CARUSO: For AP600, in order to apply the 6 WCOBRA/ TRAC code to AP600, Westinghouse took the option of, 7 because they said the temperature never got that high, they 8 didn't do a lot of assessment work for AP600 for that 9 particular model, the hydrogen generation model. And as a 10 result, we decided we could approve it as long as they never 11 got into the area where that phenomena was important.
12 That's why we put the limits at about 1725.
13 MR. CARROLL: I understood all that, but what --
14 suppose they did get 1800, what bad happens? You get
() 15 additional energy?
16 MR. CARUSO: You get additional energy, you have 17 hydrogen.
18 MR. CARROLL: You ger .ydrogen.
19 MR. CARUSO: But the plant still has to be 20 designed -- without getting into the containment area, I 21 believe the plant -- the containment still has to be 22 designed to handle the hydrogen generation from severe 23 accidents.
24 MR. CARROLL: Sure. Okay.
25 CHAIRMAN BARTON: Before we hear the next
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183 1 two-thirds of Chapter 15, I propose a 15-minute break.
l () 2 We'll come back at five after three.
3 [ Recess.]
4 CHAIRMAN BARTON: Back in session.
I 5 The next presentation will be chapter 15, Non-LOCA 6 Analysis. Ed Carlin.
7 MR. CARLIN: I'm going to try and summarize some 8 of the stuff we did for non-LOCA analysis for the AP600.
9 In general I'm going to do a brief summary on the 10 transient codes we use, and the main one there for the 11 system analysis is LOFTRAN, I'll get into a little bit about 12 how we modified that and the various versions we're using.
13 And then I'll talk a little bit about the kind of V&V work l
14 we did for verifying the changes we made to the code. And i
() 15 then I picked one sample transient to kind of step through i 16 and show how it behaves with the PRHR and the CMT. And then 17 get into a little bit of the review status, and then people l 18 seem to want to talk about rod injection and ask questions 19 about that. I do have a couple other pictures for that I 20 can add to this. !
21 What's missing here is the calculation of DNVR.
22 MR. CARLIN: I didn't bring anything for -- what 23 did you want to know about DNVR specifically?
24 DR. CATTON: Well, I read what you had in the 25 thick report, and the thick report ;efers me to a 1973
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184 1 document for uncertainty evaluation, tell me that there were
. 2 some major modifications made in 1989.
3 Now Brian may remember, but the actual --
4 establishing a number for DNVR was a very difficult process.
5 The DNB data is all over the map. 'I don't know if you have 6 new experiments. I don't know if you took the THINK code 7 and reevaluated uncertainties in the view of application for 8 AP600. I don't know where it's at.
9 And also in reading through your documen:, it's 1
10 really difficult to figure out what you're doing. In one I 11 place you talk about 95-95, but there's no basis for the
- 12. 95-95 statement anywhere, or not even any reference to it 13 other than 1973.
14 MR. McINTYRE: Which document? )
( 15 DR. CATTON: Say again?
16 MR. McINTYRE: Which document?
17 DR. CATTON: Well, chapter 15.
18 MR. McINTYRE: You've got chapter 15 on the SSAR?
19 DR. CATTON: I have chapter 15 in front of me, and 20 section 4.4 of your SSAR.
21 The latest reference that was used in -- by any 22 discussion of THINK was a 1989 document of which we have -- j 23 at least I have none. I'm familiar with the 1973 document.
24 MR. CARLIN: Okay. I'm not prepared to go into a 25 lot of detail on the DNVR. I can tell you for the AP600 ANN RILEY & ASSOCIATES, LTD.
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185 1 because of the canned motor pumps, they coasted down so
() '2 fast, that we had trouble -- we immediately went outside the 3 old correlations limits flowwise and exit-quality-wise.
4 DR. CATTON: Your document doesn't say that. It 5 says you used the old correlations. As a matter of fact, 6 the document in one place says one correlation; in another 7 place says another.
8 MR. CARLIN: They probably -- yeah, probably using 9 the -- as long as you have full flow, the old correlations 10 are just fine. It's when you have the pumps coasting down 11 and they're still at pretty high power that we were having a 12 problem. And so they had to do new tests with lower flows, 13 and they also had a THINK from using -- or a switch from 14 using THINK to the Westar code. You probably saw that 15 mentioned.
16 DR. CATTON: One place it refers to WRB2 17 correlation, and another one it refers to the W3 18 correlation, and in the middle of it all it starts talking 19 about what you do for channel-to-channel crossflow and how 20 you fix it at some value. You can't do that. You don't 21 have any data to demonstrate what it is that I know about.
22 MR. CARLIN: Okay.
23 DR. CATTON: In any event, I think that DNVR plays 24 a very important role in most of what's in chapter 15. Now 25 I have to give you that it's most of the time the minimum 7
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I 186
[ 1 value's 3 and you -- but --
2 MR. CARLIN: Yeah.
p 3 -DR. CATTON: The data's bad. It's scattered all 4 over the place. So did you put a lower bound on the DNB 5 data and then use this? I don't think so. Because the 6 message I kind of get out of the -- what I read was that you 7 approached it the same way you did with the best-estimate 8 .LOCA, and that you throw everything into a bag and do your 9 statistical evaluation.
10 I don't think that's proper. I think your tools 11 have to be treated separately, then treat your plant 12 statistics. I don't think you did that. I think you mixed l 13 them up. And with DNB data being all over the map, I don't I 14 think that's appropriate.
() 15 MR. McINTYRE: I think we'll have to put this on a 16 plate for the subcommittee meeting.
17 DR. CATTON: I think this is an issue that the l
l 18 Thermal-Hydraulics Subcommittee probably ought to take on.
1 19 That's where it was in the past.
20 DR. CARROLL: Do I want to remember at the last 21 meeting when we looked at the reactor core -- is that the
. :22 chapter 4 stuff you're talking about?
23 MR. CARLIN: Yes, the core is in chapter 4.
24 DR. CARROLL: Well, I had the impression you were 25 using a relatively recent correlation, and it was because of I ANN RILEY & ASSOCIATES, LTD.
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187 1 the pump situation.
( ) 2 DR. CATTON: It may be, but that recent 3- correlation is not referred to in chapter 15. If they 4 indeed are, it may be you just need to rewrite chapter 15.
5 MR. CARLIN: No, I wouldn't doubt, it's not 6 mentioned in 15 because we tend to just keep referring you 7 back to 4, because we didn't -- weren't real sure of the 8 details.
9 DR. CATTON: I read 4.
10 MR. CARLIN: What they were going to use.
11 DR. CATTON: But I have an old 4. Maybe I better 12 get a new 4.
13 MR. McINTYRE: I don't know how old old is.
14 DR. CATTON: I don't'either. l
) 15 MR. McINTYRE: But I'd be surprised if it changed-16 very much.
17' DR. CATTON: The amendments are still in unopened l
18 boxes. I 19 MR. McIFTYRE: I think for the purposes of what
- 20. Ed's going to do, you're going to have to accept what he 21 says on faith, and we'll put this -- I'm sure Noel has i
22 written this down as something to cover.
23 DR. CATTON: All right.
24 MR. CARLIN: Okay.
25- DR. CATTON: You have to be careful what you give
[~')
\~-
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L
188 1 me, because I do read it.
,x 1
,.L._ )
2 MR. McINTYRE: Some of it.
3 DR. CATTON: Some of it.
4 MR. CARLIN: Okay. There's three main codes we 5 use, and two of them are based off of our LOFTRAN. And what 6 I'm referring to here is the LOFTRAN-AP code is an advanced 7 plant version of LOFTRAN and it's used for doing the systems 8 analysis of non-LOCA events. There's a sister version of 9 LOFTRAN called LOFTTR2, and this is for doing steam 10 generator tube rupture events. And when we get into 11 calculating what the DNB's going to be later and you want to 12 know the local heat flux in the hot channel or you want to 13 calculate clad temperatures and stuff like that, we use the 14 FACTRAN code.
,/ ~
() 15 This is just a -- does a section of a fuel rod.
16 For very fast nuclear reactivity insertion events we use 1
17 TWINKLE, which is a -- it's just a core model. We can give l 18 you a run in point kinetics or 1D, 2D, or 3D, but we use it j 19 in the 1D mode, and we use that for our rod ejection and rod 20 bank withdrawal from subcritical events.
21 Okay. As I mentioned, LOFTRAN's the systems 22 analysis code for non-LOCA. We've been using this for years 23 and years, licensed most to the operating plants where 24 that's been previously approved by the NRC, and they're
- 25 still using it for reload analysis for the operating plants.
l n
/ \
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1 189 1 DR. CATTON: Do you use LOFTRAN for the
()
i-~
2 inadvertent actuation of the passive heat removal system?
3 MR. CARLIN: I use the advanced plant version, 4 which is -- I'm talking about down here, where it's got the 5 AP --
6 DR. CATTON: Okay. And you're going to tell us a 7 little bit about what you did to it?
)
l 8 MR. CARLIN: Right. !
9 DR. CATTON: Okay.
10 MR. CARLIN: I think I'll step to there in a 11 second, i
12 LOFTTR2 is basically LOFTRAN again, but it's for )
13 tube ruptures, and what they did there was they just 14 basi.cally added a break flow model for the tube -- for the
,/~
's ) 15 tube rupture, they put in different options for -- the 16 operating plant typically use a lot of operator actions.
17 They have nice -- they have lots of options in there so that 18 you can simulate operator actions better. And they enhanced 19 the secondary side of the steam generator a little bit.
20 DR. CATTON: Do you get primary system phase 21 change following a steam generator tube rupture?
22 MR. CARLIN: You can, but LOFTRAN is primarily a 23 single-phase code.
24 DR. CATTON: That's why I asked the question.
25 MR. CARLIN: And when you see that appearing, that 1
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I 190 1 says you should stop --
ps g J- 2- DR. CATTON: Say it's no good from this point on?
3- MR. CARLIN: Right.
4 DR. CATTON: Okay.
5 MR. CARLIN: We'll use it very carefully.
6 All right. When we look through all the systems 7 that are in the AP600, with respect to non-LOCA transients 8 the two big changes that we can see if the PRHR and the core 9 makeup tanks. The ADS systems and the IRWST injection just
- 10. aren't used for non-LOCA events. So it was these two 11 systems primarily that we changed and added as separate 12 modules to LOFTRAN. We put them both in the tube rupture 13 version and the regular plain LOFTRAN version and we just 14 called them the AP versions.
15 MR. CARLIN: We didn't have to do any numerics 16 changes to the code. These things pretty much just sort of 17 attached on.
18 There's other minor changes, more like-they're 19' fractuations for the protection system simulating the 20 various ESF functions. Like I said, the biggest changes we 21 have made are adding these on PRHR models and the core 22 makeup tank models.
23 DR. WALLIS: PRHR heat exchanger -- doesn't that 24 have to model circulation patterns in the PRHR, which
- 25. regions have boiling and all sorts of stuff?
1 I~ )
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1 1
191 1 MR. CARLIN: In the IRWST you mean?
() 2 DR. WALLIS: Your PRHR heat exchanger has 3 convection on IRWST side.
4 MR. CARLIN: Right.
5 DR. WALLIS: And it has boiling and stuff like 6 that and do you have to model the flow patterns inside that 7 tank and -- it's a rather complicated situation --
8 stratification in the tank.
9 MR. CARLIN: The tank model we are going to use,
- 10 it's one huge tank and we assume that as you add heat to it, i 11 it homogeneously mixes, but what we discussed and l 12 discovered --
l l 13 DR. WALLIS: There's no mechanism for that.
11 4 MR. CARLIN: It's actually conservative for us to
() 15 do it that way, because what happens if you assume the 16 stratification, you dump heat in and then all the heat goes l
i 17 to the top and forms a layer and you keep all the cold water 18 down where the tubes are and the heat in the PRHR -- so by 19 keeping it all homogeneously mixed, we sort of penalize 20 ourselves a little bit and we're conservative for types of 21- events we are doing.
22 For verifying the codes, we prepared two main L 23 documents. The first one was what we called a code !
24 applicability document. We kind of went through the methods 25 and reviewed them all and checked how we were using them and l
1 ANN RILEY & ASSOCIATES, LTD.
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l
192 1 then documented for the staff any changes we were going to
() 2 3
have to make, and that was how we eventually worked our way down to we really only needed to use -- to add the PRHR and 4 the core makeup tank models.
5 Then, seeing that we're adding those two, we also 6 verified the code by comparing it against various tests and 7 these were also documented in anothe- 'f our reports to the l 8 Staff 9 Now there's three sets of tests that we use for 10 the LOFTRAN verification and the first one was a PRHR test.
l 11 This was just a component type test. It wasn't so 12 much a transient test or anything like that, but we used it 13 more to define the characteristics of the PRHR heat 14 exchanger and define what we were going to use for the heat l
() 15 transfer correlations in our model, and then from that test 16 we programmed those correlations into our LOFTRAN.
17 We got into a bit of a discussion with the NRC.
18 That test originally only had straight-tubes and the final 19 design of the AP600 ended up with C-shared tubes for the l 20 PRHR and they weren't quite convinced that what we were 21 doing was quite right, so they had us take our PRHR model l
22 and compare it against the ROSA tests, which I believe had 1 23 the C-tubes and so we also used the ROSA in sort of a blind 24 test way, because we never did get to see the answers to I 25 those tests because they don't belong to us.
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193 1 The second set of tests we did was to -- l
() 2 3
DR. CATTON:
calculations.
Could you explain that?
You gave them to the Staff.
You did the The Staff 4 compared them and said thank you very much?
5 You can come to the conclusion they must have been 6 all right.
7 MR. CARLIN: Well, we had our own that said i
8 derived and said use these correlations and then basically 9 we did sort of what you did, and they had to do the 10 comparison and say these are okay or not okay compared to 11 their tests, but we had no idea -- there was no way for us 12 to tune it because we didn't know what the answers were.
13 DR. CATTON: Well, that's a plus.
1A MR. McINTYRE: It was a blind test prediction.
() 15 DR. CATTON: Now your CMT, with LOFTRAN this is 16 natural circulation through the CMT?
17 MR. CARLIN: Right.
, 18 DR. CATTON: Single phase.
l 19 MR. CARLIN: Right. It's all single phase and it 20 ends up just pure recirculation. The CMT tests were done 21 for LOCA where you drain down also, but there's a whole l
l 22 bunch of them --
23 DR. CATTON: But that is a different code.
24 MR. CARLliT: Right.
25 DR. CATTON: This is LOFTRAN.
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1 194 1 MR. CARLIN: Right.
2 DR. CATTON: Now when you do the PRHR, that is a 3 single phase circulation through the heat exchangers, isn't 4 it also?
5 MR. CARLIN: Right.
6 DR. WALLIS: Could we go back to our previous 7 discussion?
l 8 You said it is conservative to assume the IRWSt is 9 mixed. Doesn't that give you better cooling?
10 MR. CARLIN: Yes.
l 11 DR. WALLIS: If it is stratified, you get worse 12 cooling --
13 MR. CARLIN: Right.
, 14 DR. WALLIS: -- so it is not conservative, it's 15 the other direction, isn't it?
16 MR. CARLIN: No, I want good cooling. PRHR for l 17 non-LOCA events is your main safety-related mechanism for 18 removing decay heat.
l 19 DR. WALLIS: It's for removing heat. That's 20 right -- so to be conservative you want to assume the worst.
21 MR. CARLIN: Right. I I
l 22 DR. WALLIS: Which would be stratified with the i
! 23 hot water on the --
24 MR. CARLIN: No. If you put the hot water on the !
25 top, it's all nice and cold around the tubes. If you mix it i
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195 1 all up, you keep it hot down low.
() 2 DR. WALLIS:
this devise, of the IRWST?
The tubes are down near the bottom of 3 I thought the PRHR was nearer
, 4 the. top of the IRWST?
l 5' MR. CARLIN: Let me just --
6 DR. WALLIS: Maybe I have got my geometry wrong.
L l 7 MR. CARLIN: One of these sketches --
.8 DR. WALLIS: Now where is the PRHR?
i i
- 9. MR. CARLIN: What it is going to do is you are 10 going to have a tube bundle here that is sort of C-shaped 11 that comes out --
12 DR. WALLIS: Sticks in there.
l 13 MR. CARLIN: Sticks in there and comes down here, 14 and so you come up -- you connect at the top and then it's
) 15 going to come out at the bottom --
l 16 DR. WALLIS: So it is probably conservative for i
17 awhile and not conservative other times.
18 In the beginning --
19 MR. CARLIN: Probably if you run it for a day or 20 something then yes, then you get into uncovering the tubes
- 21. but we don't run these transients that long-in general.
22 DR. WALLIS: Well, I guess I am asking because i
23- 'it's rather important, the balance between the decay heat
! 24 and the PRHR over certain periods. Isn't it that the PRHR 25- overwhelms the reactor at times --
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196 1 MR. CARLIN: Right.
() 2 DR. WALLIS: -- and at other times it doesn't, so 3 it's not unimportant how accurately you predict this heat 4 transfer.
5 MR. CARLIN: It is -- I think what you really want 6 is the integrated heat removal capability of it. For some 7 of the transients we are running that are going twenty and
! 8 thirty thousand seconds, if you are off a little bit, that 9 can add up, so you kind of want to tend to underpredict it 10 for things where you -- like a loss of heat sink, feedline 11 breaks, and losses of feedwater.
12 DR. WALLIS: What limits it? Is it the 13 circulation rate that limits it,' essentially can strike 14 equilibrium in the IRWST or is it the heat transfer 15 coefficient that limits it then?
16 MR. CARLIN: I am not sure --
17 DR. WALLIS: There is a circulation through the 18 PRHR, right?
19 MR. CARLIN: Right.
20 DR. WALLIS: It goes up and comes back. If you 21 don't get enough circulation you can't remove the heat.
22 It's just limited by flow rate and the first law?
23 Is that the mode you are in?
24 MR. CARLIN: Right. You have hot water coming in 25 from the RCS --
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197 1 DR. WALLIS: And it leaves at about the IRWST t 2 temperature.
3 MR. CARLIN: It leaves slightly above it, maybe --
4 DR. WALLIS: Not much. It's really limited by the 5 flow rate in the loop.
l l 6 MR. CARLIN: 200-300, right, so that is driving 7 the flow in the loop, that and in the core the decay heat is 8 driving the low.
9 DR. WALLIS: So maybe you don't need to worry too 10 much about your heat transfer coefficient because it is so 11 big.
12 MR. CARLIN: Yes. One of the things that when we l l
13 fool with it we have got the model divided up into so many '
14 nodes, at one time they had this flange around the entrance
() 15 section to the heat bundle, so we were saying we should 16 penalize ourselves and not use that section of tubes that is 17 inside this flange, and so we took that area off for awhile 18 but all it seemed to do is it squeezes the heat transfer 19 just farther on down the bundle and just keeps moving it and 20 maybe you lose a little tiny bit, but it's just sort of like 21 squeezing a balloon. The heat transfer just goes somewhere 22 else.
23 DR. CATTON: Yes, but that moves the center of 24 buoyancy and that changes the flow rate a little bit.
25 MR. CARLIN: Yes, It's a very small amount and O ANN RILEY & ASSOCIATES, LTD.
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198 1 you have to really do something dramatic to this thing to
() 2 really change it significantly.
3 DR. WALLIS: Well, if you have got gas in the top, 4 the same as the TMT story, if you have got noncondensible 5 gas on the top of this loop -- you've got a small driving 6 head in natural circulation.
7 MR. CARLIN: I suspect -- they don't show it on 8 here -- we don't have any pictures here that show it -- but 9 there will be some way to vent that such that you don't have 10 it, any gases in there, to start.
11 Unlike the LOCA events, we don't empty the 12 accumulators or have any other way to inject other gases in 13 there.
14 DR. WALLIS: But it is sitting there for a long
() 15 time doing nothing, and if there were a mechanism for 16 slowing having bubbles go up from somewhere else, then it 17 would accumulate at the top of the loop.
18 MR. CARLIN: Yes, they would, and I suspect --
l
.19 DR. WALLIS: And they might never start 20 circulating.
21 MR. CARLIN: I can't answer how they get them out l
22 of there. I think there is a vent system. !
23 DR. WALLIS: Well, maybe solubility is such that l 24 you never get the gas in the first place. I don't know. I 25 am just speculating.
l O
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199 1 DR. CATTON: Is there a manifold that you can
() 2 vent?
3 MR. CARLIN: I think there is but that is -- can 4 you do it remotely?
5 MR. WINTERS: This is Jim Winters again. That was 6 included in the design but I dtn't know how and Terry will 7 tell us, Mr. Schultz, when he talks about the design because 8 I have a feeling it is a solubility argument and I do know l
9 that we talked about velocities of -- that you are not i
10 accumulate once you get started. It's the ones that --
l 11 DR. WALLIS: It's the starting that is the 12 problem.
13 MR. WINTERS: It's the starting one that you have 14 to worry about and we will have to let Terry explain that l( ) 15 when he gets to Chapter 6.
16 DR. WALLIS: Excuse me. The gases are not in any l 17 of these codes?
18 MR. CARLIN: No, not in my code. No.
l l 19 DR. WALLIS: So someone would have to ask the 20 question what about gas bubbles or gas regions. The code 21 isn't going to answer it because it's not in the code.
22 MR. CARLIN: Yes. I look at that a different way, l 23 though, i 24 DR. WALLIS: Maybe solubility takes care of it. I i 25 don't know. But -- l I
1 1
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200 1 MR. WINTERS: This is Jim Winters again. There is
() 2 3
another thing. The plenum on the primary side is a large plenum and the tube sheet is vertical, se that accumulation 4 of bubbles may impact the topmost part of this, but you 5 still can get some natural circulation through the submerged 6 tubes.
7 Now I don't know how much of that they went into, 8 but I do know that the parameters given by the designers to 9 Ed to calculate the effectiveness of the heat exchanger did 10 have nonactive tubes, whether they were plugged or they were 11 not active for other reasons. So we can get a better story 12 for you, but it was considered.
13 DR. CATTON: Do you know how long between -- I 14 don't know what deaeration, there's some period, there
() 15 must -- that must probably be specified by your refueling.
16 How much gas could you accumulate in the top of the tubes 17 during that period of time? That's just a diffusion 18 problem.
19 MR. CARLIN: And then the last test we used was 20 the SPES-2 tests. The SPES was a full pressure systems 21 test. It was full scale elevation and about 1/395 volume 22 scale. And there were some steam line break tests run and 23 steam generator tube tests run, and then these were 24 benchmarked or LOFTRAN was benchmarked against these tests 25 to show that we could simulate these events.
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201 1 DR. CARROLL: I want to go back to ROSA for a
() 2 moment. Refresh my memory, staff, why is it that this data 3 cannot be shared with the licensee? Hasn't most data of 4 this nature been shared ultimately with the industry?
5 MR. CARUSO: Well, I can't really explain this, 6 because I wasn't involved in the legal --
7 -DR. CATTON: Jay, I can explain part of it.
8 DR. CARROLL: You're not licensed to practice 9 law --
l 10 MR. CARUSO: I don't remember the -- it was a 11- rather intricate argument that I didn't necessarily follow 12 at the time, so I'm not sure I can explain it right now.
13' But it had to do with proprietary rights of Westinghouse, 14 the proprietary rights of Westinghouse to design 15 information.
16 DR. CATTON: The feeling was that you could 17 back-engineer a plant.
18 MR. McINTYRE: No. The real reason that -- we 19 don't want to get to close to that data. That was staff 20 data that was run for confirmatory purposes, and we don't 21 want to get stuck paying $13 million bucks for ROSA. Okay?
22 It's a very fundamental, practical, crass, commercial 23 consideration.
24 DR. CARROLL: And was anybody suggesting that you 25 should pay 13 million bucks?
l
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202 1 MR. McINTYRE: If we don't get close to it, we
() 2 don't have to worry about it. It was the staff data. We 3 did it as a blind test, and that was a perfectly legitimate 4 way to do it.
5 DR. CARROLL: Yes, I can understand that part, but 6 it just seems to me that if we have some useful, relevant 7 information to make a nuclear plant safer, it --
8 MR. McINTYRE: It was up to us to make our case, 9 and we did.
10 DR. CATTON: The staff can't give Westinghouse the 11 data without giving it to everybody, because the staff paid 12 for it.
13 DR. CARROLL: Okay. But hasn't that been the case 14 with a lot of tests going back to LOFT and --
) 15 DR. CATTON: I don't know what the story was with 16 LOFT. Well, LOFT had its own --
17 DR. KRESS: That wasn't plant-specific or 18 design-specific.
19 MR. HUFFMAN: This is Bill Huffman, member of the 20 staff.
21 It's a little more complicated, at least in my 22 opinion, in that-I don't think that the staff wants to 23 charge Westinghouse for this data. I think especially l 24 research would love to be able to disseminate this data to 25 the entire world. But there's a proprietary claim on the ANN RILEY & ASSOCIATES, LTD.
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r 203 1 data, and Westinghouse claims that this data can be used to i
[%lT 2 back out proprietary information on AP600 and will not agree 3 to let Jerry, who ultimately generated the data, to release 4 it. Even though they don't have this specific constraint on j 5 the NRC, they have it on Jerry.
l 6 MR. McINTTRE: I think the question, Bill, is why 7 don't you give it to Westinghouse, and that's a different 8 question.
9 MR. HUFFMAN: Because we will not give it to 10 Westinghouse without releasing it to the entire world.
11 MR. CARUSO: Then it looks like we did research 12 for Westinghouse.
13 DR. CARROLL: I'm just a poor dumb engineer. I 14 don't understand --
) 15 DR. CATTON: I don't either, Jay, and we had 16 meetings on it.
17 MR. CARLIN: All right. The next thing I'm going 18 to step through, there's a -- like a sequence of events, but 19 I'm going to work with the plots up here and kind of jump 20 around a bit. Just as a sample transient to kind of work 21 through I picked a loss of normal feedwater, and I picked 22 this one because you get the PRHR actuated and the core 23 makeup tanks and the PRHR actually runs for a little while 24 with forced flow and natural circulation. So in this 25 transient what happens here is the accident starts at 10 l
l
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I 204 1 seconds. We completely lose all feedwater flow. And n
( 2 gradually the RCS starts heating up.
\_-)
3 And then about 84 seconds the level in the steam 4 generator drops down to the low steam generator level 5 setpoint and the reactor and the turbine get tripped.
6 That's at point 2 here. Okay? So there's a sudden drop in 7 the temperatures, you see the delta-T between the hot leg 8 and the cold leg drops real quick. Okay? Now we just have 9 decay heat now, but there's still nothing coming into cool 10 the primary system, so the level keeps dropping, you're 11 boiling water away, and when you get to point 3 here, you 12 hit another low-level setpoint in the steam generators, and 13 that's when you turn on the PRHR. That occurred at 150 14 seconds into the transient.
C
( ,%/ 15 Now in this event the reactor coolant pumps are 16 continuing to run at this point, and over this range here, 17 region 4, the PRHR is taking out a lot more heat from the 18 RCS than you have decay heat.
19 I want to jump ahead just for a second. This is 20 the PRHR's heat-removal capacity. And so when we first 21 started it and the pump -- reactor coolant pumps are l
a 22 running, the PRHR takes out a lot of heat from the RCS, and l
23 l it's dipping down as the transient goes on, but that's i 24 because the temperature's going on. Its heat-removal 25 capability is highly influenced by the temperature you're ;
l
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205
-1 feeding to the heat exchanger.
() 2 And so you keep cooling the primary system down 3 until you get to this point 5 here, and once you get to the 4 low cold leg temperature setpoint, that generates an 5 s-signal, which actuates the core makeup tanks, trips the 6 reactor coolant pumps. I think it also isolates the steam l 7 lines. And when you trip the reactor coolant pumps, l
8 suddenly you go into natural circulation in the PRHR and the j 9 heat-transfer in the PRHR drops off-real fast down to it's l
10 about a percent and a half.
11 Now initially now at this point we have PRHR 12 cooling us down, but now we've got the CMTs running also. I 13 want to step back.
14 DR. SEALE: If I may make a comment.
, -w
.% 15 MR. CARLIN: Um-hum.
16 DR. SEALE: You characterize the event in 1,000 17 seconds as suddenly going into natural circulation. I think i 18 that's an intriguing adverb to use for that process.
l 19 MR. CARLIN: In terms of the scale of the plot, 20 which is over 30,000 seconds --
21 DR. SEALE: Yes.
22 MR. CARLIN: This is pretty sudden. The pumps 23 coast down fast on this and you're --
24 DR. SEALE: Well, I'm looking at that nearly 25 vertical line there, and at the -- well, anyway.
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I 206 l
l 1 MR. CARLIN: Okay. So --
() 2 DR. SEALE: Suddenly.
3 MR. CARLIN: At this point now we've got the PRHR
,4 and the core makeup tanks cooling you down, and so the 5 temperature still continues to drop. The core makeup tanks 6 are doing two things for you. One, they're borating the I
7 system to make sure you don't go critical again, and they 8 also tend to -- they're two -- 2,000 cubic foot tanks, you 9 take hot water out from the RCS, and then inject cold water, 10 they're actually storing heat. So they tend to be like a --
11 a heat storage system. And as they store heat, they -- the 12 driving head for the core makeup tanks is the density 13 difference between the fluid in the tank and what's coming 14 in from the RCS. So its flow rate starts dropping off as (s
(_,) 15 you keep heating the core makeup tank up.
16 Now eventually the core makeup tanks, the flow 17 gets lower and lower and lower, and eventually when you get 18 to a -- this point, the flow is so low that the core makeup 19 tanks aren't really removing any heat for you anymore, and 20 all you really have removing heat from the RCS is the PRHR.
21 But as I said before, the PRHR's heat removal rate is 22 dependent upon the temperature coming in.
23 Now at this point we've lowered the RCS 24 temperature down into the 400-degree-type range, and at this I
l 25 point the PRHR's heat removal rate is less than the decay
['
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1
I 207 1 heat you're producing.
.s t
%-)
i 2 So, you start he?, ting the RCS back up again. As 3 you heat the RCS back up again, the PRHR's heat removal 4 rate's going to increase, and eventually it'll come back 5 into equilibrium with the decay heat and it'll once again 6 match it and then it'll start turning the temperature around 7 and the temperature will go back down.
8 Just a couple other plots here. There's a plot of 9 the CMT's injection flow rate I was talking about. When it 10 first came on, we get upwards of around 100 pounds per 11 second, but as you keep recirculating fluid in there and it 12 gets warmer and warmer in that tank, the flow rate drops off 13 and keeps dropping off until it eventually will stop. Okay?
14 Now tha criteria we're using for this accident (3
\__) 15 is -- generally we don't have a problem with DNB during this 16 event, so I didn't bring any DNB plots. What we use for 17 criteria in this is we don't want to ever fill the system 18 water-solid, the primary system. So our criteria is here --
19 is to always maintain a steam bubble. And this is !
l 20 pressurizer completely filled and then this is the 21 pressurizer water volume. And so the transient's only --
22 DR. CARROLL: What bad happens when you go solid? l 23 MR. CARLIN: What's that? ;
24 DR. CARROLL: I say what bad happens when you go 25 water-solid?
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208 1 MR. CARLIN: The pressurizer safety valves aren't l( ) 2 designed to pass water, so you could possibly -- the next 3 thing you would have to do is possibly fail them open. And l 4 so now I've gone from an anticipated transient to a LOCA.
l 5 An anticipated transient you're supposed to -- this started 6 out as a loss of feedwater. You're supposed to be able to 7 go out and figure out why the feedwater pumps stopped, clear 8 the fault, and go back to power. Once you go into the LOCA
! 9 you're not going back to power that afternoon. You've 10 increased from one level of accident to another level.
11 DR. CARROLL: That is considered in the PRA 12 analysis, the potential for damaging the safety valves?
13 MR. CARLIN: In the PRA? I don't know.
l 14 DR. CARROLL: Okay. We'll ask at the appropriate
) 15 time.
l 16 DR. CATTON: That's just a 15 or 20-percent 17 difference, I mean, you're going from about 800 up to 18 1,600? If you went another hundred, you would be solid.
19 MR. CARLIN: Right.
20 DR. CATTON: And with these kind of calculations, 21 10 or 15 percent should be in your PRA.
22 MR. CARLIN: This probably also answers another l
23 question, how do we size the CMT tanks. Bob wants lots of 1
2-4 water for LOCA. I don't want too much water, because I 25 don't want this whole thing -- I've got to put the water ANN RILEY & ASSOCIATES, LTD.
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! I l
i 209
- 1 somewhere when it goes into the RCS. So this'll tend to set 2 upper bounds, these overfilling transients.
[_s\_s}
3 DR. CATTON: It can also make your pressurizer 4 bigger.
5 MR. CARLIN: Yep. We've -- the prescurizer on 6 this plant --
7 DR. CATTON: Is bigger.
8 MR. CARLIN: It's -- the normal two-loop 9 Westinghouse plant has a 1,000-cubic-foot pressurizer, and 10 our nominal volume here is 1,600 cubic foot. This is 11 pressurizer plus the surge line water volume that -- the 12 surge line's about 100 cubic foot. So we're 600 cubic foot 13 bigger than a regular two-loop plant.
l I
14 DR. CATTON: So that helps you with the minimum as {
()j f'
15 well as the maximum.
\
16 MR. CARLIN: Right. They tend to -- they made the j 17 pressurizer bigger, but they tend to steal that -- the 18 margin they put in there by filling up with water for 19 regular operational transients. I don't get a whole 600 20 cubic foot of extra steam space for anything.
21 DR. CATTON: The swell of the CMT water eats it 22 up.
23 MR. CARLIN: Yes.
24 Okay. Now at this point I said before we 25 submitted two WCAPs for the codes on -- one was on that code l
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210 1 applicability document and then another one was a V&V report
() 2 that contained all the test comparison results, and that's 3 all been given to the NRC for a while now. They've asked a 4 lot of questions on it, and we've responded to them all, and 5 they've all been placed in those WCAPs and reissued. And as i
(
l i
6 of right now I don't know of any open issues on the codes. ,4 7 Chapter 15, the -- as far as I know there the --
8 there's no open issues. We had two major issues within the 9 past year. One of them was dealing with GDC 17 and l 10 considering losses of offsite power in non-LOCA analyses.
11 The staff's current interpretation has been different from 12 what we've been using for the operating plants. It's being l 13 interpreted to expand into assuming a loss of offsite power ,
14 for all non-LOCA events. So last year around this time we
() 15 redid the SSAR all over again and took a loss of offsite l 16 power for all events.
17 The other big issue we had in the past year was 18 ATWS, and we completed analyses and a report and submitted 19 that in January of this year. And as of now I don't know of 20 any open issues on any of these.
21 DR. CATTON: What specifically did you do to the i
22 LOFTRAN? I mean, you put in another tank. Did you do any l 23 changes to the phenomenological modeling example, friction 24 factors and things like that?
25 MR. CARLIN: Nothing. Everything stays the same.
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211 1 DR. CATTON: So now for an existing plant, would (f ) 2 LOFTRAN track it right down to almost zero flow accurately?
3 Because your passive heat removal system circulating flow 4 can be a fairly low velocity.
5 MR. CARLIN: Yeah.
6' DR. CATTON: And what the codes have in them now
! 7 doesn't deal with that very well. And also it's a natural 8 circulation balance. The same could be said for the CMT.
9 You can't just use a rho v squared times c sub d.
10 MR. CARLIN: Yes, you're right.
11 DR. CATTON: Because you get into the linear 12 range.
13 MR. CARLIN- Right. We have --
14 DR. CATTON: Did you fix it?
) 15 MR.'CARLIN: Basically for --
, _16 DR. CATTON: It's a trivial fix.
l 17 MR. CARLIN: In what way?
18 DR. CATTON: You just have a constant over 19 Reynolds number plus your cd. You didn't do that, I take 20 it.
21 MR. CARLIN: In the tubes, in the steam generator 22 tubes and along the_ core they've done that. They did that 23 in regular LOFTRAN a few years back. They aren't using like 24 a fixed --
l 25 DR. CATTON: Could you find out for me what l .
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l 212 1 exactly you do to calculate the pressure drop in those two
() 2 loops? CMT circulation loop and your PRHR.
3 MR. CARLIN: Yes. We can find --
4 DR. CATTON: And I'm interested in a very low l 5 Reynolds number.
6 MR. CARLIN: Okay.
7 DR. CATTON: What might be a good thing to do is 8 what's the lowest Reynolds number you have to' deal with, and 9 it may be big enough.
10 MR. CARLIN: In a loop that's not being cooled by 11 the PRHR, you do go to zero, zero flow, in the main loop.
12 DR. CATTON: So it's no good down from ON, but --
13 then with a big pipe it's pretty hard to get a Reynolds 14 number that's low enough to give you a headache. In the G
/ 15 smaller lines it might be.
16 MR. CARLIN: Okay.
17' DR. CATTON: I have another question. That is, 18 instrumentation to follow the course of an accident -- is 19 there somewhere I could find the delineation of that j l
20 instrumentation? i 21 DR. CARROLL: Chapter 7.
22 MR. WINTERS: This is Jim Winters again --
23 DR. CARROLL: 1.97 and you'll find it all 24 described in Chapter 7, which we reviewed last time.
25 CHAIRMAN BARTON: Last time.
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213 1 DR. CATTON: Oh.
) 2 DR. CARROLL: And I asked some funny questions.
3 DR. CATTON: You did?
4 MR. CARLIN: I don't think you'll see -- we used a 5 lot of the same functions as all the operating plants do, if 6 you are familiar with them. The only thing is when you have 7 a S signal now you are not turning on the SI pump, you are 8 actuating the core makeup tanks and tripping the reactor 9 coolant pumps and low steam generator level used to actuate 10 emergency feed but on this plant it turns on -- it opens the 11 PRHR exit valves, so it should be real similar.
12 There's a few extra new functions but it should be 13 real similar to what we have been using the past for most 14 things -- for the trip logic and for the ESF functions.
() 15 ADS is obviously all new. There's all sorts of --
16 DR. CATTON: There were some questions about 17 qualification in that the instrumentation was there but it 18 wasn't qualified for anything other than a DVA so how could i 19 you track it?
20 Anyways, I wasn't involved in Chapter 7.
21 DR. CARROLL: I think the problem you are talking 22 about has pretty well been solved.
23 DR. CATTON: And they do qualify for severe 24 accidents? That's news to me.
25 DR. CARROLL: I had one more -- what was the l
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1 214 1 question? I seem to have a hangup on ROSA today.
2 Ivan,- did you guys on the Thermal Hydraulic 3 Subcommittee look at the results from ROSA in sufficient 4 detail to satisfy yourself that there wasn't something there 5 that Westinghouse should know about? No big surprises?
6 DR. CATTON: There were some big surprises in ROSA 7- but$ I think when Research started digging into them, l
8 following our-harassment, most of them could be explained l
and most of them were the results of lack of -- they were 9
- 10 really differences that were causing problems, levels of 11- where pipes connected and things like that, and they could
.12 explain away the anomalous behavior.
13 I think it was a good exercise for the Staff, 14 although I don't think it was worth the money. I don't 15 agree with Tom. $13 million was too much.
16 DR. CARROLL: Well, now the point I am getting at~
17 is I would hate to see the first AP600 have an accident and 18 .have the Staff know something that Westinghouse should have 19- known when they were designing the place.
20 DR. CATTON: Oh, I don't think that will happen.
l 21 DR. CARROLL: Okay. I am just asking the 22 question.
l 23 DR. CATTON: See', the ROSA was more for the high 24- pressure end, much like SPES, and where the problems come 25 both in calculation and in behavior is in the low pressure i
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i 1
215 1 end.
( j 2 DR. CARROLL: I know that.
3 DR. CATTON: I made that argument and the 4 committee overruled me, but --
5 DR. CARROLL: I voted with you.
6 DR. CATTON: Okay -- anyway it is OSU and 7 Westinghouse did its own testing with OSU.
8 DR. CARROLL: As did the Staff.
9 DR. CATTON: That's right, so to answer your 10 question, I don't think so.
11 DR. CARROLL: Okay. Tom, would you --
12 DR. KRESS: I agree with Ivan, all except the part 13 about the part about the --
14 DR. CARROLL: Well, you'd be wrong --
O
( ,/ 15 [ Laughter.]
16 DR. SEALE: I had to keep them apart the whole 17 time.
18 DR. CATTON: I was wondering how long that would 19 take.
20 Bob, you sit out on those. Do you --
21 DR. SEALE: I had to keep them apart the whole 22 time.
23 DR. CARROLL: Can you think of anything?
24 DR. SEALE: No , I think most of the things we saw 25 seemed, as Ivan indicated, were because of peculiar
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216 1 differences in the way in which the plumbing was put
() 2 together and then having one tank do the job of two or two 3 tanks do the job of one and that kind of thing.
l I
4 DR. CARROLL: Okay.
5 MR. CARLIN: In conclusion, for the AP600 we went 6 through, when we got the codes modified for what we think we 7 need to simulate. DNB did some test data, performed all of 8 the Chapter 15 analyses and they have all been reviewed by 9 the NRC and with the exception of the last question you 10 asked me, I don't have anything else to do for Chapter 15 11 unless they are going to jump up.
12 DR. CATTON: Except for the DMVR?
13 MR. CARLIN: Yes.
14 DR. CATTON: And I think there it is more of
) 15 establishing the basis.
16 MR. McINTYRE: Let's talk about that for a second. i I
17 If you look on page 4.5-5 of the SSAR -- l 18 DR. CATTON: Over there on the table.
19 MR. McINTYRE: 4.4-5 -- I have it over here -- and i I
20 we're talking about DNB technology and it talks about it at-21 the end and then it goes through and explains the primary !
22 DNB correlation and says we use WRB-2 -- it was developed 23 based on mixing being inapplicab]e to the specific condition
.24 for AP600, then we used the W-3 where the primary DNB ;
25 correlation is not applicable, and that is consistent with i
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217 1 what Ed said.
l 7 1 V) 2 Then it gets down to the end and talks about the I 3 modification that we did to make it fit the AP600 and i
4 references a 1995 WCAP which is the summary of the tests l i
5 that we did to look at the low flow rates. l 6 DR. CATTON: I don't have your 1995 document and j I
7 Noel is going to send me Section 4.4. Mine is too old.
l 8 MR. McINTYRE: I think you can xerox these two 9- pages.
i 10 DR. CATTON: That is what he is going to do. l 11 MR. McINTYRE: And it will --
12 DR. CATTON: Send them to me.
Is 13 MR. McINTYRE: And without having the 1995 -- we 14 will go back and see what we can --
() 15 DR. CATTON: But you remember the effort from a 16 long time ago.
17 MR. McINTYRE: Yes.
18 DR. CATTON: The data is spread over a factor of
'19 three or four, and the question is what do you do with it in
- . )
20 order to get a DNB that meets your 95-95, and in the past it L 21 was coupled to the code.
l 22 Now the code talks about a revision in 1989 so the 23 combination of the code and data needs to be revisited and l
24 where is that done?
-25 MR. McINTYRE: I believe it is done in the 1995 l
1 I
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218 1 WCAP AP600 --
2 DR. CATTON: So I am going to read about that when 3 you send it to me.
4 MR. McINTYRE: -- low flow critical heat flux te::t 5 data analysis. Yes -- I am sure you probably have one. We 6 will get you another one. At one point we sent in about 150 )
7 reports and it could be --
8 DR. CATTON: Well, they don't always come to me, 9 particular now. They have to come through some circuitous 10 route.
11 DR. CARROLL: Us consultants just don't get that.
12 DR. CATTON: We don't get the proper treatment 13 anymore.
14 CHAIRMAN BARTON: Any more questions for Ed?
15 DR. CARROLL: And tomorrow we are going to be 16 introduced first.
17 DR. CATTON: I am not going to be here. tomorrow.
18 DR. CARROLL: Oh , that's right.
19 CHAIRMAN BARTON: The next section -- radiological 20 consequences analysis. Jim Grover.
21 DR. POWERS: Mr. Chairman, I looked through this l
22- and I think I have had sufficient interaction with the Staff I 23 on some of the questions being addressed here that I had 24 best recuse myself and encourage the committee not to draw 25 conclusions should I squeeze my knuckles or pound my head or O ANN RILEY & ASSOCIATES, LTD.
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219 1 something like that in the course of this presentation.
2 CHAIRMAN BARTON: Understood.
3 DR. WALLIS: Mr. Chairman, before we move on, I 4 had some questions about some things in this fat document.
5 CHAIRMAN BARTON: All right.
6 DR. WALLIS: Such as the -- in the locked rotor 7 transient, do we get to look at that or is this your 8' business or someone else's?
9 The.inside temperature in one of these figures 10 gets to 1800 Fahrenheit and stays there. I couldn't see any 11 reason why it should do that.
12 It goes off the edge of the chart still at 1,800.
13 And --
14 MR. CARLIN: You have to show me or tell me what
() 15 the figure --
16 DR. WALLIS: There's nothing about where it goes 17 after that. This is figure 15 337.
18 [ Pause.]
19 I couldn't understand the mechanism for 20 maintaining the temperature at this level.
21 MR. CARLIN: Well, this is a short-term plot.
22 It's only for 10 seconds.
23 DR. WALLIS: Well,,there's nothing ever shown for
- 24 what happens after that, either.
25 MR. CARLIN: It's going to go down, because the O ANN RILEY & ASSOCIATES, LTD.
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220 1 heat flux -- if you look at the power transients, it's
() 2 dropping and dropping and dropping.
- 3. DR. WALLIS: Well, this is the highest temperature 4 mentioned in this whole document, isn't it, in terms of a 5 plot of anything? So it would be interesting to know why it 6 goes up to 1,800 and stays there, and also where it goes 7 later.
8 MR. CARLIN: Where it's going to go later is it's 9 just going to cool down again, because --
l 10 DR. WALLIS: Something is keeping it up.
11 MR. CARLIN: You still have three pumps running.
12 DR. WALLIS: Something is keeping it up there for 13 most of this figure.
14 DR. CARROLL: The temperature you're talking about 15 is --
16 DR. WALLIS: Clad inside temperature.
17 DR. CARROLL: Heat clad temperature?
l 18 MR. CARLIN: Yes.
l 1
19 DR. WALLIS: And 1,800 seems a pretty high 20 temperature for -- in view of the --
21 MR. CARLIN: Right off the top of my head I can't 22 explain why it went direct to that point, but --
23 DR. WALLIS: This is one of the few parts of this 24 document where something happens that just might b'e of 25 interest, and then sort of just -- there's no explanation
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1 l
221 1 for why it goes up to 1,800 and stays there, and there's
() 2 nothing about how it ever comes down again. So I thought 3 that was an interesting part of the document, and worth I 4 asking about.
5 MR. CARLIN: This is also, if I'm not mistaken, 6 this is the clad temperature at -- just at one spot.
7 DR. WALLIS: And also there's, you know, there's 8 some assumption mysteriously made that the heat transfer 9 coefficient says that the magnitude and time dependence of 10 the heat transfer coefficient between fuel and cladding have 11 a pronounced influence on the thermal results. And then you 12 simply said it's assumed that this heat transfer coefficient 13 becomes 10,000 Btus per. There's no explanation about why 14 it should be that value. It's just assumed.
() 15 MR. CARLIN: That sounds like just -- I picked a 16 big number. j 17 DR. WALLIS: Well, that's right. I 18 MR. CARLIN: Which is - I tried to --
19 DR. WALLIS: Anyway --
20 MR. CARLIN: The highest peak clad temperature.
21 DR. WALLIS: It would seem that since you then go 22 on to say the steam reaction can become significant above l
12 3 1,800.
24 MR. CARLIN: Um-hum.
25 DR. WALLIS: So it seems mysterious why the
[ -
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I N I 222 11 temperature goes up to 1,800 and stays there without having
() 2 any explanation for why.
3 DR. CARROLL: So you don't get metal water 4 reduction.
5 DR. WALLIS: Is it because you are getting a metal 6 water reaction or what is it?
7 MR. CARLIN: No, it starts at 1,800 approximately. #
8 DR. UHRIG: I thought there was a 1,725 limit.
9 DR. WALLIS: Anyway, maybe we can have an 10 explanation for that sometime in more detail about that 11 particular --
12 DR. CATTON: How are we getting to 1,800? I 13 thought there was a 1,725 limit.
14 MR. CARLIN: That's just for LOCA.
) 15 DR. WALLIS: Oh, this is more interesting than 16 LOCA. It gets hotter.
17 MR. CARLIN: You can get it hot for this, but this 18 accident's over in seconds. It's not something that goes on 19 and on and on.
20 DR. WALLIS: But you don't show us. You don't 21 show us that.
22 MR. CARLIN: Yes.
23 DR. WALLIS: You should show to the end of the 24 accident when things are brought under control, not just the 25 beginning when. things begin to get interesting.
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223 1 Now I was concerned throughout the document, many 2 times there were assumptions I couldn't understand, like --
3 which sequence _is this here? The statement such as no more 4 than 50 percent of the rods experiencing clads damage will 5 experience center line melting. This is an ast,umption. No l 6 more than 50 percent of the actual length of the affected )
I l
7 fuel rode will experience melting. Assumption. Of rods 8 experiencing center line melting, only a conservative j 9 maximum of the innermost ten percent will actually melt.
10 And I forget which event this is, but these just seem to be 11 pulled out of the air, these assumptions, a 50-percent this, l 12 50 percent that, 10 percent this, 10 percent that.
! 13 MR. CARLIN: When you do a plant design like this, l
14 we do the accident analysis in parallel with one another, 15 and they do the design in parallel with one another. So I 16 do these analyses and Jim Grover does a dose analysis. We 17 both start at the same time. So what we tend to do is we 18 make up a number that he thinks he can live with if I fail 19 this much fuel. So he starts a dose analysis. And if I 20 fail to -- say we're going to agree on ten percent and if I 21 calculate 5.5, I'm saying in there that I've used an 22 assumption of 10, which gets used in the dose analysis, and 23 with the analysis, though, I'll say that it's less than ten, 24 that I calculated less ten is what I'm trying to say.
25 DR. CATTON: So you use what he's going to -- you O ANN RILEY & ASSOCIATES, LTD.
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224 1 use the number that you gave him as a design goal --
()
i 2 MR. CARLIN: Right.
3 DR. CATTON: In what you design.
4 MR. CARLIN: And I have to stay under that limit.
5 DR. WALLIS: I guess this is the uncontrolled j 6 withdrawal of rod cluster, control rods or something. This
)
7 scenario. There are lots of these statements like a small I 8 fraction of the fuel is assumed to melt. Well, what does l
9 that mean? And why assume? Why not calculate?
10 MR. CARLIN: It's more because of we're trying to 11 also when we do it like say this is a real plant and you're 12 going to do reloads. You don't want to do this accident 13 analysis over and over and over. So you set up a goal or a i
14 boundary and then you try and always stay under that with j
() 15 the actual calculated values. You only license this one
)
16 fixed value with a ten-percent failed, say.
17 DR. WALLIS: This is one of the few times in this 18 document you talk about actual damage to the core in terms 19 of melting and so on. And the numbers seem to be based on 20 assumptions rather than calculations. It seems to be one of 21 the more important things to calculate right.
22 DR. CARROLL: Maybe the word " postulate" would 23 help, postulating a --
24 DR. WALLIS: Then there are strange statements 25 such as although fuel damage is assumed to occur, no fuel ANN RILEY & ASSOCIATES, LTD.
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r 225 1 damage is anticipated. Now what is that supposed to mean?
() 2 Does-it or does it not occur? These are unsettling 3 statements.
4 MR. WINTERS: This is Jim Winters. I think 5 they're very settling, because -- and well thought out.
6 This is a document that describes two things. It describes +
l l 7 the plant's impact on the environment as a result of
! 8 accident. That's the Jim Grover part, which you're going to l
9 hear about in a little bit. And it also describes or shows 10 that when we analyze events, they stay under the assumptions 11 for impact.
12 What it is trying to tell you is that we've l 13 assumed some fuel melting or any of the -- pick any of the 14 ones that you've had there, to analyze for impact on the 15 environment, and then do a plant transient analysis to show l 16 that we never even get there. The plant's okay if it did 1
i 17 get there, but it doesn't get there. That's what that last l
l 18 sentence that you read indicated to me, that we've done an 19 analysis to show that even if it got there, the impact on l 20 the environment is within limit.
21 DR. WALLIS: But why assume it in the first place 22 if it's not going to happen? Why have these 50-percent t
23 numbers that appear out of the air that aren't related to 24 anything?
25 MR. CARLIN: Because I have to calculate some ANN RILEY & ASSOCIATES, LTD.
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226 1 number out to six digits that's good for an 18-month fuel
() 2 cycle.
3 DR. CATTON: Part of it's defense in depth. If 4 _they did the calculation, you wind up with nothing 5 happening, you don't need a containment.
6 DR. WALLIS: So you go through all this analysis 7 to predict that nothing happens, and then you suddenly 8 assume well, let's assume something terrible happened or 9 something that's not terrible -- strike that -- something 10 like major core damage occurs. Why would you want to do 11 that when you've already predicted it hasn't happened?
12 MR. WINTERS: So that you can show that if it does 13 occur, that nothing else happened.
14 DR. WALLIS: But why do it? Why, if you know it's
() 15 not going to occur, assume it at all?
16 DR. CARROLL: I think the best argument I've heard 17 is the reload fuel design situation. -Every time you get a 18 new reload, you have to do an analysis, and the staff has to 19 review and approve it. So they're setting the basis in this 20 for the remaining life of the plant in terms of what they 21 have to show in reload analysis. Instead of having to do 22 the detailed analysis, you just have to show that you're 23' staying below certain numbers.
24 DR. POWERS: It is. Whereas I admire the level of 25 technology that has been reached'by thermal hydraulics, I am O ANN RILEY & ASSOCIATES, LTD.
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227 1 unwilling to hang my hat on it and so I have to ask the
() 2 question what is it -- what it is that happens if indeed the 3 sage seers of thermal hydraulics are wrong? Not that that 4 ever occurs,.I understand, but in the off chance that --
5 DR. CARROLL: It's a very low probability.
6 DR. WALLIS: It's almost a certainty that they are 7 wrong.
8 DR. POWERS: Is there capability in the plant to 9 assure then in this extremely unlikely event that they have 10 taade an error that is consequential, but still nothing 11 propagates onwards. I think that is the heart and soul of 12 defense-in-depth that's applied for the design basis 13 analysis.
14 DR. WALLIS: Well, maybe that doesn't come through l 15 in the report because --
{
16 DR. POWERS: Well, I am not sure that the 17 Applicant is responsible for articulating the 18 defense-in-depth concept. I think they are more subject to 19 it.
20 DR. WALLIS: It's only in this particular section 21 we are talking about this particular event that having gone 22 through all the hydraulics and thermal analysis you suddenly 23 start making assumptions _about damage to the core. 1 i
l 24 It really strikes the reader. Why is he doing it l 25 for this particular event? This is the ejection of control l
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228 1 rods.
() 2 3
MR. CARLIN: I think you'll see stuff like that in there and you'll see it --
4 DR. WALLIS: You don't see it in other chapters.
5 MR. CARLIN: In the locked rotor ones.
6 DR. WALLIS.: I don't think so.
7 MR. CARLIN: Because in these accidents you are 8 allowed to fail a small amount of fuel also.
9 A lot of the other non-LOCA events the criteria is 10 no fuel failures, 11 DR. WALLIS: Yes.
12 MR. CARLIN: So I've got to live with that.
13 DR. WALLIS: So it's something about something I 14 don't know about that for some of these events you are 15 supposed to assume fuel failures and some of them you are 16 supposed to show it cannot happen.
17 DR. CARROLL: You are allowed to show -- to have 18 fuel failure is what he is saying.
19 MR. CARLIN: Yes. The non-LOCA events are divided 20 up into using the ANS -- what is it? -- an 18.2 criteria.
21 There's Condition II events, which are anticipated 22 transients. You have to be able to show no fuel failures 23 and if you clear the fault you bring the plant back up, j l
24 Condition III accidents, you can have very small 25 fuel failures.
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f 229 l 1 DR. WALLIS. Well, the red flag to me is first the
() 2 word " assumed" -- which I don't like to se.e anywhere -- and
)
3- then when what you are assuming is fuel damage, which would 4 seem to be an important thing to be certain about rather i
5~ than assuming. l 6 That is why I focused on this particular section.
7 Maybe I don't understand what is going on.
8 DR. SEALE: What they are doing I think is setting 9 up the case for a consequences calculation --
10 MR. WINTERS: Right.
11 DR. SEALE: -- that will attempt to set forth the l 12 idea that if the thermal hydraulicist is dead wrong, we f 13 aren't -- Ed, that is.
14 [ Laughter.]
) 15 DR. SEALE: And, you know, it's the whole idea l
l 16 that plutonium is the most toxic substance in the world.
l 17 If you take that. kind of characterization, there i 18 is no rational analysis of what comes after that, so what J 19 this is is an attempt to set up a rational basis for a i 20 evaluating the capability of defense-in-depth to cope with 21 the consequences at an unjustifiable accident.
22 You can't justify it on the basis of the analysis 23 but it is defense-in-depth.
24 DR. WALLIS: Well, that -- now you are bringing in 25 an entirely new subject of conversation that hasn't been l
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230 1 discussed all day.
l
() 2 3
DR. SEALE:
defense-in-depth thing.
But that is what is behind the i j
4 DR. WALLIS: So a naive person reading this 5 document reads through the whole thing and suddenly finds 6 that only on a couple of pages is there actual mention of 7 damage to the core and there it seems to be assumed rather 8 than calculated. That is what concerned me.
i 9 MR. CARLIN: Value used for calculating doses 10 probably was assumed, yes -- a bounding number was assumed.
11 DR. WALLIS: Why only in this particular sequence 12 of events?
13 MR. CARLIN: I think you will see it in a couple 14 of them. You will probably see it in rod ejection --
15 DR. WALLIS: Why not everywhere?
16 MR. CARLIN: -- locked rotor. Those are Condition 17 IV events. 1 18 DR. WALLIS: And ejection of control rods.
19 MR. CARLIN: Yes. I think most of those events in j 20 this section are Condition II and you are not allowed to 21 have any fuel failures at all, but a rod ejection is a l
22 Condition IV. You are not allowed to have a limited amount 23 of fuel failure.
24 DR. WALLIS: There may Pe some regulatory history 25- that is understood but the layman reading this would say,
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231 1 gee whiz, they are now talking about core damage here, and
() 2 they are assuming it rather than calculating it.
3 MR. GROVER: This is Jim Grover. This is really 1
4 getting into the radiological consequenced area.
5 This set of assumptions has a long history. If 6 you look at most of the operating plant FSARs you will find 7 similar statements.
8 I believe this goes back to -- I can't remember --
9 DR. POWERS: Jim, it goes back to 1954.
10 MR. GROVER: Well, I expect it goes back to around 11 the mid '70s. We had a WCAP that Dan Rischer was the author 12 of on rod ejection and it was a result -- it was an outcome 13 of that where we started using these assumptions.
14 We had the defined number of fuel rods, a bounding 15 number of fuel rods that were assumed to be damaged, and 16 that Laere was a reactivity transient that would cause l
17 heating within the fuel itself, and this is defined as a 18 center line melt. It was also defined as being restricted 19 to a small portion of the rod because -- and I don't want to 20 throw out numbers, but it seems from my recall that we were l
21 dealing with very small axial sections of the rods, so when 22 choosing 50 percent this was a conservative approach.
i 23 The idea behind this was we went through this 24 agony of this rod ejection to come up with a boun' ding i 25 approach and said let's live with this instead of having to i
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232 1 recalculate all the time.
(q j 2- < DR. KRESS: I tell you, I_think you're criticism 3 is. valid because what we have here is assumptions without
-4 having the basis for those assumptions discussed'here 5 'because they have such a long history that they go back 6 quite far that there are people who understand the basis, l
l 7 but a new reader reading ~the thing just sort of --
8 DR. WALLIS: Why invoke them now when you are now 9 able to calculate things?
, 10 DR. CARROLL: We are now touching on something l
11 dear to my heart, and that is you are exposing the fallacy l 12 of these so-called --
l 13 DR. KRESS: Welcome to the Design Basis Space.
14 [ Laughter.)
/ 15 DR. CARROLL: Logically what you should be doing 16 is looking at these kind of events on a risk basis and 17 saying I can discard anything that'has a probability of less 18 than 10 to the minus --
I t
19 DR. KRESS: And this one would have been discarded 20 on this basis, l-21 DR. CARROLL: And this one would have been
'22 discarded.
j 23 DR. POWERS: Well, before you toss things out, I i
l 24 will remind you that there is a certain hubris associated 25 with the belief that Man is so advanced that we can 4 1
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233 1 calculate things with great confidence, and I have always
() 2 3
been comfortable with a certain amount of prudence doubting that ability.
4 I think it is an issue that we still have to 5 confront ourselves in connection with how we interface these 6 design basis ideas with probabilistic risk assessment in our 7 modern calculational technologies, but one thing I am very 8 confident of is Mr. Grover is not responsible for that.
9 DR. CARROLL: Yeah, but he is responsible for that 10 funny looking necktie-he wore.
11 [ Laughter . ]
12 DR. POWERS: That I won't exonerate him from.
13 MR. GROVER: Well, looking at the neckties around 14 the Board here, most of these are what my old secretary k 15 referred to as engineer's neckties.
16 [ Laughter.]
17 MR. GROVER: This is-not an engineer necktie 18 although I am an engineer.
19 DR. SEALE: I would only say, Graham, that one of 20 the things that this whole argument does is it forces us, in 21 line with Dana's comments about hubris, to think the 22 unthinkable in terms of the accident process, if you will, 23 and to ask ourselves if containment and things like that 24 serve a purpose.
25 Because if you did the risk assessment, we would ANN RILEY & ASSOCIATES, LTD.
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234 1 l get rid of them.
2 DR. KRESS: And with respect to the question of 3 how much defense in-depth, there's a real issue, and I think 4 what Dana would say is if you took a rod ejection accident 5 and did an appropriate uncertainty analysis on it, and chose 6 something like a 95 percentile damage on the core, that 7 might be an appropriate level to say we'll incorporate as a 8 defense in-depth, or_something like that.
- 9. There ought to be some way to fix those numbers, 10 and right now I think they are fixed just by deterministic 11 calculation and tradition. -
12 DR. SEALE: Tradition and deterministic analysis.
13 DR. KRESS: There ought to be a better way to fix 14 those.
) 15 DR. POWERS: And certainly I will invite members 16 to attend a Fuel Subcommittee meeting where we will be j 17 looking at rod ejection accidents in altogether too much 18 depth.
19 DR. KRESS: Wonderful 20 MR. GROVER: Okay. I prepared a fairly brief 21 presentation. I am just going to go over the changes in 22 methodology and source term fro.n what we have in currently 23 operating plants. We have got the change from the TID 14844 24 source term and other assumptions that are within the Reg.
25 Guides, to utilizing the NUREG-1465 source term. This O ANN RILEY & ASSOCIATES, LTD.
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235 1 includes a drop in having a gap fraction of 10 percent down
() 2 to between 3 and 5 percent, depending upon the type of 3 accident.
4 DR. POWERS: Jim, do you think that constitutes a 5 limit that may come back to bite you if you go to higher 6 burnup fuels?
7 MR. GROVER: I don't really believe it does. I 8 know -- I am aware of the issues going on with the 9 reactivity insertion accident and this talking about the 10 fuel being powdered.
11 DR. POWERS: I am just thinking about higher gap 12 inventories in the case of high burnup fuel.
13 MR. GROVER: Yeah. It does appear to me, from 14 looking -- from a certain amount of looking at the data, (G_,/ 15 that this pertains to overall Noble gases which are 16 dominated by stable ones. I am not convinced that there is 17 a problem with the short-lived Noble gases and iodines for l
l 18 which we would have concern in the accidents. I 19 DR. KRESS: Would your results have changed if you l
20 had used 10 percent? Could you live with 10 percent gap?
21 MR. GROVER: Could I live with 10 percent? And 22 one of those is it all depends. You know, there are other 23 -- how many other aspects of the analysis would I be allowed 24 to keep also? Because any time you take one thing away, the 25 question is -- Do I have to give up other things, too?
[~
~
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236 1 But maybe we can get -- when we get to the slide
() 2 comparing, showing the calculated doses, maybe we can work 3 from that.
4 We have a much broader range of nuclides that we 5 are considering for release for the core melt accident.
6 Cesium has become very significant, in particular. We have, 7 instead of an instantaneous release of activity from the 8 core, again, we are talking about LOCA --
9 DR. WALLIS: What is this core melt accident you 10 are talking about?
11 MR. GROVER: This is the LOCA, where Bob Kemper 12 demonstrates --
13 DR. WALLIS: Where it doesn't happen.
14 MR. GROVER: It does not happen. That's true.
15 But for -- but-the prescription is, in the old 10 CFR 100 16 and now 10 CFR 50.34, is that we have to consider an l 17 accident for which there is a major release of activity and 18 this accident has been defined as a large LOCA in which, for 19 whatever reason -- the reason is not defined, the core 20 melts.
21 In the current operating plants, it melted, 22 essentially, instantaneously a few seconds into the 1
23 accident. That did give you time to isolate the 24 containment, close your purge valves.
25 With the new source term it says that the gap ANN RILEY & ASSOCIATES, LTD Court Reporters 1250 I Street, N.W., Suite 300 l Washington, D.C. 20005 (202) 842-0034
237 1 release starts at 30 seconds or 10 minutes into the event,
() 2 3
and then you start -- then you have an extended period of gap release and then you go into a core melt phase.
4 But, see, it is my conjec.ure that the whole LOCA
-5 with core melt is an anachronism. It is something that 6 -shouldn't still exist. It is something that was needed 7 when, you know, 20 years ago. But then with the -- as we 8 have developed PRA and the severe accident methodology, ,
9 really, the necessity for a design base accident with {
10 prescribed core melt is probably not necessary. But it is 11 part of the licensing requirement that this be considered.
{
12 DR. WALLIS: If it is necessary, it would be best 13 to put it in a separate chapter saying that, although we 14 have shown nothing like this can ever happen, now we are
() 15 going to just assume it did happen and look at the 16 consequences. But when it is put right in sequence with 17 showing it can't happen, that just seems very -- very 18 strange.
19 MR. GROVER: Well, you should be directing this 20 more to the other side of the room, because, in fact, I had 21 some sentences in there talhing about just how unlikely this 22 was and this wasn't really design basis accident, and I was 23 requested to remove those sentences. And we can live with 24 that. But this is essentially the standard that we are 25 working with.
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238
- 1 MR. EMCH. This is Rich Emch, I'm the Chief of the l
-( ) 2 Radiation Protection Section, NRR. He assumes that source 3 term because, essentially, the regulations tell him he has 4 to do that. Okay. That's a little bit of an 5 over-simplification, but the regulations, Part 100, 6 indicates that for siting purposes, he has do a calculation 7 that assumes, for dose consequences, he has to do a 8 calculation that assumes a certain amount of fuel damage.
9 We have already had, you guys have already had a 10 fair amount of discussion today, and this is probably the 11 top of the mountain of that discussion about the disconnect 12 between the carefully calculated thermal hydraulics and 13 nucleonics and all that sort of stuff of the Chapter 15 14 accidents. And then when you start to say, okay, now I am
()
7x 15 going to make the leap from that to the leap of how do we 16 calculate dose consequences for comparison with the various 17 dose acceptance criteria that are in Part 100 and Part 50 18 and the in the SRP that describes how we do those things, 19 and this is -- this is the top of that heap, so to speak.
20 You know, this is the criteria that the Reactor Systems 21 Branch and people like that use, say that you don't get fuel 22 melt, okay, you keep the core covered and you don't get fuel 23 melt.
24 But in the early days of this industry, when the 25 decision was made, the TID source term days back to -- I L
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l 239 1 think it's '62, I am not sure.
() 2 3
MR. GROVER:
MR. EMCH:
1962.
Okay.
Yes.
In the early days the decision 4 was made that this was the way we were going to assess 5 accidents. And the source term, the NUREG-1465 source term 6 is an attempt to update that science'to some degree, and 7 that's why we are using, you know, using that on the AP600 8 instead of the TID source term.
9 The NUREG talks about five phases and it 10 progresses from the first three phases, which we evaluate 11 for design basis accidents, and then it goes on to talk 12 about the full five phases of a core damage accident, a 13 severe accident, and we use the first three. The Commission 14 has made the decision that we will use the first three of
("h
' (_j/ 15 those phases to evaluate DBA dose count consequences.
16 DR. CARROLL: Back in'the time frame you'were 17 talking about I sat in the ACRS room at 1717 H Street and we 18 made a presentation on a plant we wanted to build called j I
19 Humboldt Bay, and it had something called emergency core !
20 cooling systems that we wanted to put in, and the then 21 Director of Regulation got up and made a speech and said all 22 we will accept is a passive containment. We will never give 23 you credit for things that rely on pumps and valves and that
- 24. sort of thing. You just got to have a strong enough 25 containment. And that's the way it stood for a long time, O ANN RILEY & ASSOCIATES, LTD.
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r 240 1 and that's how you got to this kind of a source term.
2 MR. GROVER: Yes. You had to demonstrate that --
l 3 essentially this was a containment demonstration as well as 4 siting, that you could not exceed certain dose limits with a
~
I 5 core melt accident, or they say a core damage accident.
6 MR.-EMCH: I may be a little out of order, but I 7 would suggest that we would be happy to have a discussion 8 with you guys in general about the whole philosophy of this I
9 sort of stuff, but this gentleman is trying to explain to 10 you what was done on the AP600.
11 MR. GROVER: You know, we sort of have to live 12 with the game as -- with the rules as they are.
13 Like I said, we have the change release timing, 14 and again this applies to the LOCA with core melt, to go l 15 from instantaneous to a release timing that encompasses over 16 an hour. We have iodine chemical form now dominated by 17 cesium iodide instead of elemental iodine. The old source 18 term was essentially 91 percent elemental, 4 percent 19 organic, 5 percent particulate. Now we have 95 percent 20 particulate, the cesium iodide, and only .1F percent in the 21 organic form. The remainder is elemental.
22 We also have revised dose acceptance criteria with 23 the rewriting of Title 10 to remove dose limits from part 24 100,11, putting them into 50.34. Instead of the defined 25 thyroid dose, 300 rem thyroid and 25 rem whole body, we now l
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i 1
241 4 1 have a 25 rem total offective dose equivalent as the limit.
) 2 We also have what we call a sliding two-hour window assumed
- 3 for the LOCA site boundary dose, which is essentially the
]
4 worst two-hour period. For the other accidents, the worst I 1
l 5 two-hour period is the first two hours.
6 The accidents -- if any of you have a copy in 7 which -- this says 6.25. It's supposed to be 25. l An ;
8 oversight on my part. In the copies that were handed out it 9 should be blacked out.
10 CHAIRMAN BARTON: It was blacked out. It does i 11 read 25.
12 MR. GROVER: There were some early copies that got 13 out in the back of the room.
l r
14 Okay. This is the list of accidents that were I 7s
'( 15 analyzed. We have, you know, we've already been talking l
l 16 about the LOCA where we've reported -- these are the doses 17 reported in the SSAR as opposed to the limit, you know, the 18 defined dose limit, and we have a LOCA, we're reporting 24.5 19 for the worst two hours with a dose limit of 25. And then
[
20 you can see down the list the other two -- the other three L 21 accidents all involve fuel damage, rod ejection, and locked i ..
22 rotor, fuel in the core, and the fuel-handling accident, of 23 course, fuel being handled in cold condition.
24 And the acceptance limits are lower, either 25 25 percent or 10 percent of the full acceptance criteria.
i
'l i
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242 1 Then we have the steam generator tube rupture
() 2 accident which is analyzed for two conditions, one with an 3 iodine spike that is initiated by the reactor trip at the 4 beginning of the accident, and the other much lower 5 probability in which the accident occurs at a point in time 6 when you have a fully developed iodine spike that is 7 elevated reactor coolant iodines.
8 For the preexisting iodine spike, because of the 9 much lower probability, the staff has assigned the 10 acceptance limit for dose at the full 25 rem, whereas with 11 the accident-initiated spike it's 10 percent of that value.
12 Similarly this is done with the main steam line 13 break.
14 And then we have a small-line break outside I 15 containment which typically on an operating -- current 16 operating plant would be the failure of the letdown line, 17 but on the AP600 the letdown line never exits the 18 ccntainment, and the line used there is a sample line.
19 DR. KRESS: Now looking at numbers like your 20 preexisting iodine spike, is that okay? I mean, you exceed i 21 the dose limit.
22 MR. GROVER: No. No.
23 DR. KRESS: That's a 25. That's not a .25?
24 MR. GROVER: No, that's 25. I 25 DR. KRESS: Okay.
l O
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243 1 MR. GROVER: Yes.
2 DR. KRESS: So --
3 MR. GROVER: I tried to be careful to remove the 4 decimal point.
5 DR. KRESS: To get that dot off there too. Okay.
6 DR. WALLIS: What's the basis of this dose limit 7 column?
8 MR. GROVER: The regulation limit is 25 rem.
9 It's --
10 DR. WALLIS: It's up and down depending upon the 11 accident?
12 MR. GROVER: The reductions in that value, the )
1 13 6.25 is 25 percent, and the 2.5 of course is 10 percent. l 14 And these are from the standard review plan. Now of course 15 if you look in the standard review plan, what is stated 16 there is 10 percent or 25 percent of Part 100, because the 17 SRP has not been rewritten to reflect the changes that have 18 been made by 50.34.
19 DR. WALLIS: Those limits are different because of 20 some sort of probabilistic assessment?
21 MR. GROVER: It is -- I'm quite sure -- I know 22 it's a probabilistic thing. I'm not exactly sure how it was 23 applied. If you look at --
24, MR. McINTYRE: Let the staff ask for that one.
25 MR. EMCH: Rich Emch again. Some of it's O ANN RILEY & ASSOCIATES, LTD.
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244 1 probabilistic. There's a number of different arguments that tO)
G' 2 go into it, and again it's the sort of thing where it is 3 described, the limits, the various limits are described in 4 the SRP.
5 Just as an example, to look at it, some of it is a 6 belief that some accidents are more likely than others, and 7 are intended to be, should be, much lower consequence kinds 8 of accidents. For example, when you're looking where it has 9 accident initiated versus preexisting, the technical 10 specifications for most plants have a one microcurie per 11 gram of dose equivalent iodine-131 as their usual limit, so 12 to speak. They're not supposed to exceed that for more than 13 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> at a time. And so we used that as the starting 14 point for the accident-initiated spike case and then we e
( ,/ 15 assign a spike above that during the course of the accident.
16 That is a very real phenomenon that's been seen at 17 a number of plants when there's been tube ruptures and 18 things like that, and so that's -- and tube ruptures are 19 considered to be a, you know, something that happens from 20 time to time, and so the belief is that we should have a 21 lower limit for those things. The preexisting spike case 22 they started off with a value of 60 microcuries per gram, 23 which is well above anything that we've ever seen at -- and 24 that's the instantaneous limit. And that's well above 25 anything that we've ever actually seen at a powerplant. And i 1
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245 1 so the belief is that that's very unlikely, and we allow the 2 full limit for that.
3 DR. CARROLL: All of that thinking that led to the 4 10 percent and the 25 percent predates really sophisticated 5 PRA analysis. It was sort of a gut feeling.
6 MR. EMCH: That's correct, yes.
7 MR. GROVER: There was a later effort. There is 8 an ANSI standard 51.1 which was an attempt to update the 9 previous 18.2 and they went into categorizing the accidents, 10 attempted to, by probability and they assigned dose limits, 11 but the industry and the Staff are not utilizing 51.1 to any 12 extent -- but it is an interesting document to look at 13 because you see the categorization oy probability, by dose 14 limit.
() 15 DR. CARROLL: Did the Staff endorse that standard 16 in a Reg Guide or --
l 17 MR. GROVER: I don't know exactly what happened to 18- the 51.1 but all I know is that we a e not using it and the 19 Staff is not using it.
20 DR. CARROLL: Okay, 21 MR. GROVER: But I like to refer to it to provide 22 argument sometimes, but that is all I have been able to do 23 with it.
24 When I look specifically at two accidents, just 25 because they are significantly different than those in the O.'
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246 1 current operating plants, the first is the fuel handling
() 2 accident and one,of the changes in our analytical model was 3 that with most of the iodine in the form of cesium iodide 4 and thus nonvolatile we assumed that none of this was 5 released out of the pool, that it essentially stayed in the l 6 fuel assembly and the only thing that would happen to it is 7' it entered into the water.
l l
6 DR. CARROLL: So this is the case where I H 9 physically damage the fuel and open up the cladding but I 10 have no heat-up?
11 MR. GROVER: Right. This is -- essentially you 12 have a cold assembly. You drop it and assume you break all 13 the rods.
14 Also with a nonsafety grade spent fuel pool
() 15 cooling system, it is assumed that the pool -- that the same 16 time you drop the assembly we lose coolant and the pool 17 heats up, enters a boiling state, and the iodine from the 18- pool -- some is' released over time.
19 We have -- there is a conversion of cesium iodide 1 l
l 20 to elemental iodine at the concentrations that would exist 21 within the pool and the pH that would exist in the pool, 22 because it is an acid environment, and acid environments l
23 promote conversion of iodine to the more volatile elemental 24 form.
25 There would st_11 be much, much less than 10 l
1 c
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I 247 1 percent in the elemental form regardless -- I assumed it was (q 2 all elemental for conservatism, and then there assumed a 3 partition coefficient of .01 for the elemental iodine. That 4 is -- this whole pool boiling thing is different from
(
5 operating plants.
6 DR. WALLIS: You put this table where you compare 7 SSAR dose with the dose limit you showed us.
8 MR. GROVER: Yes.
9 DR. WALLIS: Yet this SSAR dose seems to be based 10 on all these assumptions, so it could easily be off by a 11 factor of 100 or something.
12 MR. GROVER: You could say that about almost 13 anything though.
14 DR. WALLIS: Not the thermal hydraulic -- l 15 [ Laughter.]
16 MR. GROVER: Okay. In radiological consequences 17 space -- '
18 DR. POWERS: We all know not to say bad things 19 about thermal hydraulics. j 20 DR. WALLIS: This seems bizarre. This seems going 21 back to the '40s or something, isn't it, in terms of 22 rational accident analysis?
I 23 I mean since you are going to make all these 24 assumptions, why make this comparison where you are worried 25 about whether two is bigger than three or not.
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248 1 You put all these assumptions where you say you
() 2 3
can assume it's 100 percent though you are much less than 10 percent. I don't understand that.
4 DR. CARROLL: I think he's saying the assumptions 5 he is making are conservative.
6 MR. GROVER: I am making conservative assumptions.
7 DR. WALLIS: Then why are you so worried about --
8 why is it important to get the table where a number is under 9 another number when everything is so tremendously off anyway 10 is what I don't understand -- or maybe --
11 CHAIRMAN BARTON: You only try to comply with the 12 -regulations.
13 DR. POWERS: Jim, just for clarification on this, 14 you have assumed a partition coefficient of .01 for some
( 15 period of time. There seems to be something missing here.
16 Is it assumed that there is quantitative transport 17 away from the surface of the pool as soon as -- as you 18 partition?
19 MR. GROVER: Do you mean that -- well, we have a 20 panel in the fuel building that is designed to open at high 21 temperatures just so that you will vent that room, because 22 there is an identified problem with'if you had boiling of 23 water here that the steam and activity could make its way 24 into various parts of the auxiliary building which was not 25 desirable, so if you enter into a high temperature condition l
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249 1 the relief panel will open to vent that building.
() 2 Maybe I am not answering your question.
3 DR. POWERS: Yes. Let me explain what my problem 4 is.
5 If I assumed a partition coefficient of 10 to the 6 minus 13th and I was willing to wait long enough, I would 7 eventually get all that elemental iodine out of the pool and 8 so now I am asking -- what I am trying to understand is how 9 fast does the elemental iodine come out of the pool. How l 10 much of it comes out?
11 MR. GROVER: I am trying to remember and I cannot 12 the steaming rate.
13 DR. POWERS: So what you do is base it on the 14 steaming rate.
) 15 MR. GROVER: It is based on the steaming rate.
16 DR. POWERS: I understand then. That is the
'17 . missing piece of information there. I 18- DR. CARROLL: One percent of what ':Us in the --
19 DR. POWERS: Well, I understand what a partition 20 coefficient is.
21 MR. GROVER: For a pound of water that releases 22 steam, one percent of the activity is --
23 DR. POWERS: You just said the steaming rate, and 24 that's fine.
25 MR. GROVER: Okay. l 1
l 1
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I I
250 1 DR. POWERS: Essentially you had instantaneous
() 2 mass transport off the surface driven by the steaming rate.
3 MR. GROVER: Right 4 DR. POWERS: That was just the missing point, I 5 guess.
6 DR. KRESS: That doesn't address anything that 7 might be above the top of the water 8 This is only what comes out of the steam and I am 9 not sure that that adcoesses your full question of what-10 about the rest of the surface area.
11 DR. POWERS: Oh, he just hadn't taken any credit 12 at all for anything else. I mean he's -- you just pumped it 13 out, right?
14 MR. GROVER: This steams out and then goes
) 15 directly to the environment.
16 DR. POWERS: And you assume that elemental lodine 17 is essentially a noble gas and --
18 MR. GROVER: Well, not essentially a noble gas.
19 There is a partitioning.
20 DR. POWERS: Once it is out --
21 MR. GROVER: Once it is out --
22 DR. POWERS: -- it acts just like a noble gas.
23 MR. GROVER: I am assuming no removal, no played 24 out.
25 DR. KRESS: But the volume, this .01 percent s
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251 l 1 occupied is the volume of the steam.
? ,-
l
(%-)) 2 DR. POWERS: Yes.
l i
i 3 DR. KRESS: And I am saying you have a surface of I 4 water with a volume above it which is basically full 5 containment and if you were to go to equilibrium with that 6 full containment you would have about --
I 7 DR. CARROLL: No , no, no, no -- we are outside the 8 containment.
9 MR. GROVER: We are in the auxiliary building at 10 this point.
11 DR. CARROLL And it's going directly to 12 atmosphere is the assumption.
J 13 DR. POWERS: His partial pressure of iodine that 14 is in this steam and he has a steam flow rate, so he has a l'8
( ,) 15 release rate, so he is in Fat City at this point and he can 16 calculate --
l 17 DR. KRESS: Okay, I see. I 18 DR. POWERS: -- a site boundary division now.
19 DR. KRESS: It's not a closed system.
20 MR. GROVER: No, it's not.
21 DR. WALLIS: And what is the basis of the first 22 bullet there?
23 MR. GROVER: The cesium iodide is not gaseous.
24 DR. KRESS: The basis of that is dictated.
25 MR. GROVER: Therefore, bubbles of gas leaving the
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l 252 1 fuel assembly will carry essentially none.
~s 2 DR. WALLIS: It can't spit out particles?
\
('%s) 3 MR. GROVER: It would conceivably, but there is no j 4 reason to think that it would.
5 DR. WALLIS: Well, bursting bubbles make aerosols 6 and things.
7 DR. POWERS: Is the amount of release he would get
)
8 from some entrainment due to bursting bubb]es, is absolutely '
9 minuscule compared to what he getting -- i 10 DR. WALLIS: Well, you have non made a 11 calculation. That's what I would like - when you say it is 12 assumed to be, it would make more sense to say we have made
]
13 an analysis and done experiments with boiling pools with 14 particles in them and we found there is some basis for it.
,G t
) 15 DR. POWERS: He probably did that in his head.
16 DR. WALLIS: This stuff is riddled with the 17 expression "is asn a.ned to be" .
18 MR. GROVER: That is true. I don't deny that. We 19 have never -- no.
1 20 DR. WALLIS: That should be -- that should 21 disappear from this whole regulatory business. "Is assumed 1
22 to be" is not an acceptable way of doing engineering. l 23 MR. GROVER: We are not -- I hate to say this, but l 24 we are not doing engineering at this point.
l l 25 DR. WALLIS: So this is a throwback to the Dark l
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253 1 Ages.
f~'T 2 MR. GROVER: We are doing things, many things that d
3 are here are admittedly prescriptive.
4 DR. UHRIG: This basically came out of Three Mile 5 Island, did it not, the fact that the --
6 DR. SEALE: No , it is before that.
}
7 MR. GROVER: I am not sure.
8 DR. UHRIG: The cesium iodine?
9 DR. SEALE: Yeah.
10 DR. POWER.S: This predates -- I mea:. this whole 11 thing here probably was -- the calculation probably could 12 have been done easily in 1974. j 1
13 DR. KRESS: Except bullet one where if you assume j 14 a particular form is 95 percent.
(r~) 15 DR. UHRIG: That is what I am talking about. ;
16 DR. KRESS: That did kind of come after Three Mile 17 Island.
18 DR. FONTANA: Well, yeah, but that's when it 19 became popular.
20 DR. FOWERS: Well, now, '74 they -- they knew it.
21' DR. FONTANA: You know, it was understood long 22 before then, it just wasn't anywhere. It was after Three 23 Mile Island.
24 DR. SEALE: They had already identified 25 particulate cesium iodide in spent fuel long before TMI.
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254 1 DR. POWERS: There are certain people at the table
() 2 3
that don't actually believe in cesium iodide particulate.
[ Laughter.]
4 DR. POWERS: But that's another subject we won't 5 bring up.
l 6 DR. KRESS: Because he is a chemist and not a --
7 DR. WALLIS: Are the assumptions your assumptions
! 8 or are they made because the staff required them?
9 MR. EMCH: This is Rich Emch again from the NRC 10 staff.
11 DR. WALLIS: The staff requires that you make 12 them, is that it?
13 MR. EMCH: This is Rich Emch from the NRC staff.
,~
14 To a large degree, he is doing some of these assumptions
^
15 because that's the way the Standard Review Plan says to do 16 this.
17 I want to just quickly point that the nature of 18 the DBA design basis of dose consequence calculations, they 19 are intended to be very conservative. They are intended --
20 they are not supposed to be best estimate calculations.
21 They are intended to be very conservative. And, therefore, 22 when you see these words about something was assumed, that f 23 is correct, it was assumed because we are not saying that l 24 that is the absolute number. l l
25 And when we do these kinds of calculations, if you !
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l l
l 255 1 look at meteorology, for instance, the idea the meteorology
() 2 values that we use are what is called 95 percent meteorology i 3 and you will see this number, 95 percent, from time to time
( 4 in other kinds of assumptions as well. The idea is these 5 are supposed to be very conservative calculations and the 6 idea is that you are supposed to be using assumptions that 7 will be worst case 95 percent of the time. You won't be any
, 8 worse than that 95 percent of the time.
1 9 So I mean I see your frustration with the process, 10 I hear it, but the process, the policy that has been set up l 11 is that is the way we handle DBA dose consequence 12 calculations. They are very conservative calculations.
13 DR. POWERS: Put it another way perhaps is to say l 14 that, unlike a well developed field where all the problems !
() 15 have been solved, like thermal. hydraulics, we still have 16 major technical challenges in understanding how fission 17 products behave.
18 DR. FONTANA: Yeah, but this doesn't help.
l 19 MR. EMCH: That's true. Frequently when we use an 20 assumption it is because it is a whole lot easier just to 21 use that assumption and we come up with acceptable results, 22 as opposed to doing hours and hours of -- or going off and 23 developing new calculations or whatever, or a lot of 24 analysis. Yeah, that's true.
25 DR. CARROLL: One thing that may help, Graham, O ANN RILEY & ASSOCIATES, LTD.
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256 1 although it isn't the case today, not many years ago almost
/m
( ) 2 every nuclear plant that was licensed was challenged by 3 intervenors. And you had to keep it simple. The staff had 4 to be able to stand up there and say, you know, anybody 1
5 ought to be able to see that this is a bounding calculation 6 and it is full of conservatisms, everything is safe.
7 DR. KRESS: And the other point is practically all 8 the plants out there were licensed on the basis of this type
) 9 of activity. And the question is, has this resulted in an 10 adequately safe set of plants? The proof of the pudding 11 there is what does this PRA tell you, bacause that's the 12 only way we know how to measure risk.
13 The PRA probably tells you that you did result 14 with a -- by going through this pescess, there's a A
!(,,) 15 disconnect. There is no direct connection between this and 16 what reality, in terms of safety, is. But by going through 17 this process, then after the fact doing a PRA, we come to l 18 the conclusion, yeah, this probably worked in most cases.
19 There might be a few exceptions.
20 MR. GROVER: See, in actuality, if you drop a fuel 21 assembly, what happens is you get no release, because the 22 fuel rods are relatively ductile and they --
23 DR. POWERS: Bounce.
l 24 MR. GROVER: They bend.
25 DR. KRESS: But this kind of process wasn't
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257 1 intended just to say what happens when you drop a fuel
( 2 assembly, or wasn't intended to say what happens when you 3 have a rod withdrawal accident. These were surrogates.
I 4 That when you design with these things in mind, you are l 5 supposed to end up with a plant that is robust against all l 6 severe accidents, regardless of the probability of 1
7 occurring.
8 That is the philosophy. And whether or not it is 9 a technical defensible philosophy we could debate from now 10 on, and I would like to hear this presentation that 11 suggested that I would be very, very --
12 MR. EMCH: Rats. I was hoping you forgot that I 13 said that.
14 [ Laughter.]
() 15 DR. KRESS: But that is a debate that we have had 16 for a long time on this Committee. And the only proof of 17 the pudding is what the PRA tells you, but you have to take 18 the PRA with its uncertainties, and you have to talk about 19 why it doesn't talk about shutdown and low power, and you 20 have to factor that into it. And the question is, does the 21 process work? Well, personally, I think it has worked about 22 as good as it could when you include other defense in-depth 23 concepts that are used available to us back when most of the 24' plants were licensed.
25 DR. CARROLL: But every so often it has had a ANN RILEY & ASSOCIATES, LTD.
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258 1 negative' impact --
() 2 3
1DR . KRESS:
DR. CARROLL:
Oh, yes.
On the safety. i
)
4 DR. KRESS: Certainly it has. l 5 DR. CARROLL: One prime example is that this 6 instantaneous release required diesel generators to start 7 and be ready to. pick up load in 10 seconds, and we really 8 detracted from the reliability of diesel generators by 9 beating them up'that way.
f 10 DR. FONTANA: 'I think.there's really no one to 11 blame for this, but I think the advance plants missed an 12 . opportunity to rationalize the whole licensing system. You 13 had to do it --
14 DR. CAP 90LL: Well, the trouble is, the other
() 15 thing you've got to keep in mind, is to change a regulation 16 is a two-plus-year process.
17 DR. KRESS: Yes.
18 DR. CARROLL: So if you've got a silly regulation, 19 you know, you just don't say ah, let's change that sucker.
20 CHAIRMAN BARTON: I'm not sure we can solve this l 21- problem in this committee and so we ought to let Jim finish 1 22 telling us what he had to do to assure AP600 is certifiable.
23- Jim, go ahead.
24 MR. GROVER: Okay. And another thing just on the
? 25 philosophy of things, this is the last chance to get -- to O ANN RILEY & ASSOCIATES, LTD.
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259 ;
1 make sure that things are conservative. The site boundary
/~%
(J t 2 dose is not affected on the fuel-handling accident just 3 because you don't have any boiling until after the two-hour 4 period is over.
5 Again, the loss-of-coolant accident.
6 DR. POWERS: You said two-hour period, but isn't 7 that particular accident covered by the worst two hours?
8 MR. GROVER: You could apply the worst two hours, 9 but the boiling is not of consequence.
10 DR. POWERS: No, because it boils but --
11 MR. GROVER: It could boil and you would add to 12 it, but not as much as that first two hours.
13 DR. POWERS: Okay. That is the worst two hours.
14 MR. GROVER: Yes, the first two hours is the worst (3
(j 15 on the fuel-handling accident. On the LOCA we have been 16 going through an awful lot of work on the LOCA for AP600, 17 and there are -- we are dependent on the AP600 on the 18 deposition processes to remove the airborne nongaseous 19 activity. We do not have safety-related sprays, as most of 20 the current plants take credit for removal by sprays. Not 21 all, but most.
22 We have the elemental iodine deposition removal 23 model from the standard review plan was used. The 24 particulate deposition coefficient was calculated using 25 Polestar's computer model, and this combines sedimentation,
\
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260 1 diffusiophoresis, the thermophoresis. Essentially you've
{, ~) 2 got sedimentation is obvious, and we've got the thermal i
\_/
3 transfer to the containment walls, as well as steam i
I 4 condensing on the containment walls that both help transport I 5 aerosols to those wall.
6 DR. KRESS: Let me ask you a question about that.
7 Some of the Committee Members may recognize that I'm jumping 8 on a hobbyhorse here.
l 9 [ Laughter.]
10 DR. SEALE: And they go counterclockwise, you 11 realize.
12 DR. KRESS: But the source term you just talked 2
13 about on the previous slides is an amalgamation of a number 1
14 of accidents in standard plants that looked at them and
<( ) 15 decided this would be a good representation of a severe 16 accident, both the timing and the amounts of that, but they 17 represent different accidents. They're a surrogate for a 18 lot of different accidents, some of which have a lot of 19 steaming associated with them, some of which the steam is 20 there and gone before the fission products get there.
21 And the question I have about this particular 22 slide, about this particular bullet, is you must 23 associate -- must have associated that source term with some 24 accident to get the diffusiophoresis, which requires the 1
j 25 steam condensation, as well as thermophoresis, which l
<w
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261 1 requires thermal gradients calculated. So if you have a
() 2 3
stylized source term that doesn't represent any particular sequence at all, what's the justification for picking any 4 particular value for steam, the timing of the steam 5 condensation and the timing of the thermal gradients with 6 respect to that particular source term? What's the 7 rationale. That's my question.
8 MR. GROVER: Well, for the AP600, if you are -- if 9 you have some event that is driving you into core melt, it 10 will turn into a large-break LOCA, because your ADS stage IV 11 will open.
12 DR. KRESS: Now you're -- but -- but you're using 13 the timing of this source term that's specified. There's a 14 timing specified.
() 15 MR. GROVER: I know. I prefer to use --
16 DR. KRESS: That has nothing to do with AP600 17 lairge-break LOCA is what I'm telling you.
18, MR. GROVER: It is very close to what our MAP code .
I 19 predicts for --
20 DR. KRESS: Oh, now that's a different argument.
21 Now if you can show me that and show me that -- but your 22 rationale here for AP600 is all of the accidents basically 23 lead to a large-break LOCA, and the timing of the releases 24 and the steam relative to the timing of the source term 25 that's a stylized source term is close enough that you can 1
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262 1 put some credit -- credibility to the diffusiophoresis and
() 2 3
the thermophoresis parts of your removal?
MR. GROVER: I believe so. Also, we have to 4 remember that this is -- we again we're wandering away from
,5 mechanistic into prescriptive here,.because we have said --
l 6 DR. KRESS: I know, and that's what bothers me. l l i j 7 MR. GROVER: No , I mean just in the fact that
! 8 there is core' melt.
l 9 DR. KRESS: I understand that. l l 10 MR. GROVER: Because we had to fail a number of 11 passive components in order to starve the core of cooling in 12 order to get the core melt. So --
13 DR. KRESS: Let me ask the staff a question. In 14 any of the past ten CFR 100 type of safety analyses have you l r"N
(_) 15 given any credit for diffusiophoresis and thermophoresis in 16 removing fission products from the atmosphere? In any past 17 licensing.
18 DR. SEALE: They are polling.
19 MR. GROVER: The question is I think to try to 20- determine whether it's going to be slim or none.
21 DR. KRESS: The answer is no. I knew that before 22 I --
23 DR. CARROLL: Why don't you tell them? They're 24' having a hard time.
25 MR. SNODDERLY: Dr. Kress, before I answer that --
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l 263 1
1 I'm sorry, Mike Snodderly, Containment Systems.
/~'\ 2 Before I answer that question, I'd like to take a
! k ,/
s 3 crack at what I think you may be getting at, because you're 4 right, 1465, yes, the stylized source term. So now we're 5 going to try to give credit for diffusiophoresis and 6 thermophoresis that are very dependent on the 7 thermal-hydraulic profile. So how do you go about 8 determining the thermal-hydraulic profile?
9 What we the staff did in our confirmatory 1
10 calculations, we chose the 3BE accident, because that was 11 seen as a major contributor to risk, more than the 12 large-break LOCA. And so then we looked at some MELCOR l
13 analyses and CONTAIN analyses to determine the j 14 thermal-hydraulic profile, and we also looked at what MAP
() 15 calculated for 3BE and for the LOCA, and as Jim said, all 16 the accidents start to -- or the' thermal-hydraulics profiles 17 look similar because once ADS Stage IV actuates, you see 18 that that dominates. But anyway, that's how we -- that's ;
19 the thermal-hydraulic profile we chose to determine what --
20 what was the steam fraction, what was going on inside.
21 DR. KRESS: Okay. So --
22 MR. EMCH: This is a fairly new area for us, okay?
23 You're absolutely right. If I look at operating reactors, !
24 you're right,' we use the TID source term to maybe -- you l 25 could say to maybe to.some degree this kind of stuff was
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264 l
1 sort of built in because you had the 50 percent coming out
() 2 3
of'the core and then 50 percent immediately being, you know, and so maybe that kind of accounted for these sorts of 4 things. '
5 But you're right, it's a new area for us in terms
! 6 of the advanced reactors. We attempted, as Mike told you, 7 to deal with it, and Westinghouse attempted to deal with it.
l 8 We got. help from.-- well, I guess I can say it -- from
! 9 people like Dr. Powers to try to evaluate this. And this is 10 the best shot we got.
- 11 DR. KRESS
- This resulted in a set of-lambdas that 12 are time-dependent. They're time-dependent because you --
- 13 this Polestar model has agglomeration in it and your l
l 14 particle size is changing? This is a different question.
( 15 MR. GROVER: Well, it's dependent partly because 16 your concentration is changing. There is agglomeration 17 built into the model.
l 18 DR. KRESS: Well, you.know, the processes of l 19 lambdas only depend on particle size, not concentration.
j 20 MR. GROVER: Well, but your agglomeration is
! 2 11 probably dependent on particle -- on concentration, and also l
22 your thermal-hydraulics are changing.
23' DR. POWERS: Maybe despite my protestation that I 24 would remain silent, I think I am allowed to help on points 25 of clarification.
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i 265 1 DR. KRESS: Yes, you are.
[ 2 DR. POWERS: The time dependence comes primarily
\
- 3. because of change in thermal-hydraulics. ,
I 4 The rate at which you are condensing steam --
5 DR ,. KRESS: Does this model then not have l
l 6 agglomeration?
l 1 l 7 DR. POWERS: It definitely does.
i
! 8 DR. KRESS: It does?
I 9 DR. POWERS: But the far bigger effect --
10 DR. KRESS: See, Chapter 15 never talks -- the l
l 11 Appendix never tells you what the model is. It doesn't tell !
l l 12 how you get the particle size.
13 DR. POWERS: I Well, that is an unfortunate factor, J 14 because in fact this Polestar model is very, very close
() 15 to nelahydrous --
16 DR. KRESS: So it does have the -- I l 17 DR. POWERS: -- and --
18 DR. KRESS: -- Smolakowsky and Brownian and so 19 forth.
20 DR. POWERS: Had the speaker had a chance, he 21 would have probably put about two and a half hours if my l
22 recollection is right of comparison of code calculations 23 against experiments of various types.
24 DR. KRESS: That really doesn't bother me.
25 The question, the next question, I am going to i
( >
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[ l 266 I have, is if you just included sedimentation, what fraction
/
V) 2 of the total lambda does that make compared to the 3 diffusiophoresis and thermophoresis?
4 Is it a major fraction or a minor fraction?
5 DR. . POWERS: I won't even begin to speak for'the 6 Applicant's code. I know what it is for the analysis I did. ,
1 7 DR. KRESS: Thank you. My guess is that the 1
8 diffusiophoresis is the major part of the lambda. j 1
9- DR. POWERS: The calculations I did, I have done l
l 10 in this particular problem for the thermal hydraulics that l I
11 were provided. I make no claim to that. Diffusiophoresis {
l
- 12 is. overwhelming.
l l
13 DR. KRESS: Yes, and that is what bothers me. If 14 I were going to continue with what I would say design basis
( 15 space, where I want to be overly conservative, and have this I
16 disconnect between timing of thermal hydraulics and-timing 17 of the source term, I think my choice would have been limit '
18 the lambda to only sedimentation.
19 DR. POWERS: I'll argue with you on that.
20 DR. KRESS: Okay.
21 DR. POWERS: It may be out of place for me to 22 argue, but this is fun technical issue. l l
23 Here is where~are you conservative? Are you '
l 24 conservative in saying I am confident that gravity operates '
25 but I am not so confident that I know.how well particles i ANN RILEY & ASSOCIATES, LTD.
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267 1 grow because I have big uncertainties on collision
[q 4 2 deficiency factors, factor of 3 at least, and if you believe L/
3 an eminent scholar in this area more like a factor of 50, on 4 collision factors, I don't know what my starting particle 5 sizes are very well, so I can't be real confident where I 6 going from and to.
7 Or am I being conservative when I take -- I rely 8 on the condensation of steam and it's carrying particles in 9 that sensibly -- you are going to cringe when I say this 10 because we argued over this massively -- but for all intents 11 and purposes independent of the particle size that I can't 12 calculate very well, which one is more conservative?
13 I think I would be willing to stand up and defend 14 diffusiophoresis in a design like this might be more A
(_) 15 conservative than relying on gravity.
16 DR. KRESS: I think I would argue vociferously 17 against that position.
18 DR. POWERS: Well, I know you do, but I think you 19 need to take into account this particle size issue and the 20 gravitational collision issue versus the relatively weak 21 particle size dependence on thermophoresis --
22 DR. KRESS: But what my argument -- my argument --
23 DR. POWERS: I mean thermophoresis I think is 24 particle size dependent. I know you and I --
25 DR. KRESS: -- but my argument would go along the
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l 268 1 lines that even if I use conservative values or very 2 nonconservative values for the sedimentation, I will still 3 get lambdas that are less than the one you get for diffusiophoresis, so there's no way I can say that is 4
5 . conservative or nonconservative. )
6 If I eliminate the diffusiophoresis altogether and 7 use --
8 DR. POWERS: Well,-I mean I think you have to set 9 the ground rules here and the ground rules that I think you
.10 would like to set is saying I am not nearly so ignorant as I 11- used to be about accident dynamics and it is difficult for 12 me to argue that there isn't steam coming out of these 13 things of some nature, so now is it that I want to discount 14 totally the diffusiophoresis?
15 I think that is physically rational that you are 16 now in a position to say there is more to these accidents
- 17 than just gravity. I think we are smarter now.
18 Now which one is conservative? Do you have to say 19 it is either one mechanism or the other, or can't I start I 20 summing them together? l l
21 DR. KRESS: That is the question. Now let's I 22 examine the steam question first.
23 About 90 percent or greater of your fission 24 product release occurs during a period when you've let off 25 the hydrogen, the zirc steam reaction.
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269 1 DR. POWERS: Absolutely.
ex (mj) 2 DR. KRESS: You are basically converting most of 3 the steam into hydrogen and you are superheating the stuff 4 that is coming out, so what I see as a superheating mixture 5 of hydrogen, noble gases, and a little steam coming out into j 6 the containment -- and I am not so sure that is a situation i
7 well set up for diffusiophoretic transport to the walls. I i
8 DR. POWERS: Yes, but there are two points there, 9 think, that you have to remember.
10 When you say you are converting the steam all into 11 hydrogen, that's not quite true. You have a tremendous 12 amount of bypass flow, so your hydrogen-steam ratios are 13 not --
14 DR. KRESS: Not that great?
,ex
(, ) 15 DR. POWERS: -- not all that high. Actually, l
16 surprisingly low. .
17 The second thing is just because I put it out in i 18 the containment I don't have to put, instantaneously put up 19 the walls to be safe, and in fact it actually takes some 20 time and we have argued heroically over how fast it actually 21 occurs.
22 You get an integration when you go into 23 containment.
24 DR. KRESS: But I am still worried about my worst 25 two hours.
n
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l 270 1 DR. POWERS: But your light-off takes about 30 2 minutes.
3 DR. SEALE: Mr. Chairman, I think we ought to 4 congratulate the speaker. He's got the committee arguing 5 among themselves and has not found it necessary to say a l 6 word for the last five minutes.
l
- 7. [ Laughter.]
8 MR. GROVER: I'm noticing these hobbyhorses l 9 rocking away --
10 [ Laughter. ]
11 DR. POWERS: Oh, we haven't even gotten into 12 fractal modeling yet.
13 DR. KRESS: I would just like to close by saying I 14 think we are setting a precedent here on the use of design s
15 basis accident and that needs to be given a lot of thought.
16 DR. SEALE: Yes.
17- CHAIRMAN BARTON: Go ahead.
18 MR. GROVER: Let's see. Have we covered all 19: these? No.
20 CHAIRMAN BARTON: Is there anything left to be 21 said?
22 [ Laughter.]
23 MR. GROVER: The second point on the slide -- we 24 did have a consideration of the potential for re-evolution
! 25 of iodine because iodine would be entering into the IRWST.
i L
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271 1 After the IRWST is drained there is a heel remaining -- a
() 2 significant quantity of water that is still just boric acid, 3 non-adjusted pH and the activity -- that is, we are assuming 4 that most of the activity is coming out on the containment 5 shell and the condensing steam will wash that off into a 6 gutter system that is directed into the IRWST, and so the 7 Staff had raised the question about what about iodine 8 re-evolution and in our analysis we had an offset early-on 9 by a certain amount of cesium hydroxide assumed to be coming 10 out of the core.
11 It is modelled to be coming out of the core. It 12 is not an assumption. It is part of the characterization of 13 the activity release from the core.
14 We found, first of all, there is no impact on site
( 15 boundary dose, which is our limiting dose just because it 16 takes'about five hours to drain the IRWST. And so during 17 that period of time, you would have -- the air would be 18 flowing into the IxWST to replace where the water had been.
'19 The other thing is, after a few days, there is 20 only a small amount of activity remaining in the water 21' because we have a continuing feed and bleed operation.
22 Again, the condensing steam mixing with the water, forcing
- 23. activity out into the sump.
24 DR. WALLIS: Is that where it goes, it goes into 25 the sump?
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l 272 1 MR. GROVER: Yes. It will go into -- Terry Shultz
() 2 3
doesn't like to call it a sump because he says there is no such thing as a sump, but there isn't any other good word 4 for this vast pool of water.
5 DR. WALLIS: Is there Ph control down there?
6 MR. GROVER: And there is Ph control there. There 7 are large baskets of trisodium phosphate.
8 So what we determined is that there is, like I 9 said, only a small increase in the low population zone dose.
10 DR. SEALE: Okay.
11 DR. WALLIS: There are large baskets of trisodium 12 phosphate?
13 MR. GROVER: Yes.
14 DR. WALLIS: What are they, in pellet form or some e'"%
'Q 15 -- what are they?
16 MR. GROVER: It's granular form.
17 DR. WALLIS: Granular form.
18 MR. GROVER: In baskets. As they are exposed to 19 humidity, of course, they become pretty much a solid mass.
20 DR. WALLIS: To congeal.
21 MR. GROVER: But this is consistent with current 22 plant practice.
23 DR. CARROLL: I have always asked the question, 24 though, I can recall several times getting my five pound box 25 of sodium -- or trisodium phosphate out and trying to ANN RILEY & ASSOCIATES, LTD.
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273 1 dissolve it. It doesn't dissolve very readily.
2 MR. GROVER:
) Do you use 180 degree water?
3 DR. CARROLL: I use hot water.
4 liR . GROVER: Do you?
5 MR. SNODDERLY: Jim, you may want to mention the 6 tech spec that goes along with every two outages or every 7 two years. A sample will be taken to determine solubility 8 in a specific environment and a test as described in the 9 tech specs.
10 DR. CARROLL: Oh , you guys maybe heard me three or 11 four years ago when I worried about this.
12 MR. SNODDERLY: Yes.
13 DR. POWERS: It seems to me, I just have to ask, 14 you got your "does" part bottle -- bars in here. They have
() 15 only a certain capacity. And you have a radiolytic process i 16 going on in the atmosphere. You may have other acid 17 sources. At what does point does "does" come to an end? I l
18 mean at what point do you acidify.to the point that you have 19 lost the buffering capacity of the trisodium phosphate?
20 MR. GROVER: Well, we don't assume we have lost 21 buffering capacity of trisodium phosphate. There is a limit 22 as to how much -- when we take the accident out for 30 days, 23 and there is a definite limit to how much of the 24 hydrochloric acid can be formed from degradation of cable 25 jacketing, --
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274 1 DR. POWERS: How about the nitric acid?
() 2 MR. GROVER: The nitric acid. The nitric acid 3 seems to be a rather minor contributor as --
4 DR. POWERS: Yeah, I wouldn't think so. What is 5 your --
6 MR. GROVER: But over the 30 day period --
7 DR. POWERS: What is your atmospheric dose run?
8 It should start off, what, about two megarads in the 9 atmosphere and then decay off to a couple of hundred 10 thousand at-the end of 30 days, something like that?
11 MR. GROVER: Any words -- any numbers I came up 12 with like -- let me just draw it out of the blue, I don't 13 have numbers.
14 DR. POWERS: Do you happen to know what particular
() 15 G-value you'used for nitric acid formation in the 16 atmosphere?
17 MR. GROVER: I don't have that information with 18 me.
19 DR. POWERS: There have been some recent 20 experiments -- I can't point you to a source of the recent 21 experiments simply because it is proprietary work or 22 controlled work in Europe. They basically come up with G 23 factors of a Y2 for -- that's two molecules per hundred, per 24 hundred electron volts to the atmosphere or something like 25 that. And that's a pretty fierce nitric acid format 1on O' ANN RILEY & ASSOCIATES, LTD.
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275 1 rate.
() 2 3 report?
MR. GROVER: How does that compare to the Beam 4 DR. POWERS: Now, the Beam -- Mr. Beam. Beam 5 argues that nitric acid formation is aqueous process. I 6 don't know anybody anywhere in the world that agrees with 7 him on that.. The most I have seen, the closest I have seen 8 to acceptance cn1 that is another investigator at Oak Ridge, 9 in fact, working in waste isolation, who says that, yes, it 10 can become an aqueous process when there is a limited 11 availability of the atmosphere.
12 I, myself, have looked in vain for any evidence of 13 nitrogen radiolysis and aquid solution in the entirely of 14 literature base I have available for. I can't find anybody
() 15 who believes that. Everybody believes it is a gas phase 16; process and you form nitrous oxides in the atmosphere and 17 they subsequently hydrolyze to form nitric acid.
18 MR. GROVER: Okay. But you have said believes and 19 you said unreferenceable report, --
20 DR. POWERS: Well, I can't --
21 MR. GROVER: -- and you don't have anything else.
22 The only referenceable report I have is Beam's.
23 DR. POWERS: Okay. Well, how about ---
- 2 <4 MR. GROVER: Right off. That's the only one I can 25 think of right off.
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f
.]
276 l
1 DR. POWERS: There are some others that were some
() 2 limited experiments, only about a hundred experiments done 3 in England and a few in Canada, and I would refer you to ,
l 4 some word by Len Acker. I can probably get you detailed '
5 references on those, in something I have written undoubtedly 6 on that, because it has been occupying a lot of my attention
- 7 lately.
l 8- But there are other experiments. This more recent i 9 work was done in Europe simply to confirm it for more like l 10 accident conditions than what was done originally. And 11 basically what they are coming back and saying, yeah, Len 12 Acker's numbers are about right for the G-values.
13 MR. GROVER: Okay. Now, we had added -- we had i
14 initially sized TSP baskets solely on boric acid, and then
(\
g ,,/ 15 the mass of TSP has been increased, it.is not quite doubled, \
16 oto address acids produced post-LOCA.
17 Now, one thing.you say, when will TSP no longer be 18 effective from a dose consequences perspective, because you 19 reach a point where it really doesn't matter anymore.
f 20 DR. POWERS: Yeah.
21 MR. GROVER: Because once you get around 30 days, 22 you know, we have decayed away a lot of material. You know, l
23 for iodine to start to re-evolve, yes, you would then start '
24 increasing your low population zone dose. But I seriously ;
25 doubt that we would challenge the dose limit. You know, the i
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I 277 I site boundary dose would remain limiting, I am quite sure.
-() 2 DR. POWERS: You are probably right.
3 MR. GROVER: But it is an interesting question.
4 DR. POWERS: What is driving you out here is 5 probably the thorium, decayed iodine.
l l 6 MR. GROVER: Well, you know, because we got --
7 Iodine 131 is,the main character in this play as far as 8 re-evolution and it is --
! 9 DR. POWERS: What do you do about -- I mean 1465 -
-10 says something to you, okay, you get so much release of 11 tellurium.
12 MR. GROVER: Yes.
i
! 13 DR. POWERS: Okay. And that goes off and it does l
14 whatever tellurium does.
t 7" 15 MR. GROVER: You end up getting a lot of Tellurium i
16 32. I mean it keeps you level up on 132.
17 DR. POWERS: Yeah. And the -- so do you count the 18 decay of 132 or do you just leave it all as tellurium?
- l. 19- Tellurium stays tellurium or does it actually decay when you l
20 do these analyses?
21 MR. GROVER: My.model doesn't take into account 22 parent-daughter. So what I did with the Iodine 132, I am 23 trying to remember, at least I did at one point, I hope I 24 retained that, was I just' upped -- I mean changed the decay 25 time on the Iodine 132. I J
O[
(_-
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278 1 In fact, I looked back at TID 14844. In fact,
() 2 they mention'doing that.
3 DR. POWERS: Yeah. You just change the decay time 4 because it is exactly parallel to the Tellurium 132.
5 MR. GROVER: Right.
l 6 DR. POWERS: I mean they are in equilibrium, so l' 7 they just go exactly as each other.
8 MR. GROVER: But, again, even then, the 132 is not 9 real significant on the dose.
l 10 DR. POWERS: But at 30 days you are ten times the 11 half life, so, presumably, it is very small at that point.
12 MR. GROVER: Okay. Since we're using a 13 time-dependent release model instead of having a zero to 14 two-hour dose that was limiting it turned out to be a one to
() 15 three-hour dose limiting for the site boundary. That's 16 essentially the timing on the core melt release, because 17 your gap release says there's a ten-minute delay, your gap 18 release takes a half-hour, so you're just getting into your l
19 core-melt release, and you're well established in that, and 20 then that's -- you're getting into your one to three hours.
21 So this is when you have your peak inventory in the 22 containment before you've had any significant removal.
23 And then we were taking exceptions to NUREG-1465 24 and staff and we were beating heads, and it was -- they will 25 certainly agree it was very unpleasant at times. But we ANN RILEY & ASSOCIATES, LTD.
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l.
279 1- have dropped the.taking exceptions, particularly on low
()
f 2 3
volatile release fractions, and this resulted in having a site boundary dose in excess of the limit, and to address 4 that the containment design leakage was reduced from .12 5 percent to 0.1 percent per day.
6 DR. WALLIS: It's not going to be calculated. Is 7 tha' a calculated value or assumed value, this .1 percent.)
8 MR. GROVER: That is a design value. Essentially 9 it's a value that the utility owner --
10 DR. WALLIS: Someone designed this containment 11 building so that it will leak at this amount?
12 MR. GROVER: No. No. It's a value at which you 13 must operate the plant to, and when you do the containment 14 test, you must meet a fraction of .1 percent.
() 15 DR. WALLIS: So there is a test of the containment 16 building?
17 MR. GROVER: Yes.
18 DR. WALLIS: Okay. Thank you. That's very nice.
19 It's not an assumption.
20 MR. GROVER: 10 CFR 50, Appendix J.
21 DR. CARROLL: It's a lot of hard work.
22 MR, SNODDERLY: It's really the result of the 23 whole siting process is coming up with what your design
, 24 basis. containment leak rate is.
25 MR. GROVER: And in general we've -- about .1 ANN RILEY & ASSOCIATES, LTD.
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r I
! 280 1 percent. We've licensed plants as low as .1 percent per
() 2 3
day. The biggest problem there is verifying your ability to measure something that low, and operating plants have l l
l 4 demonstrated the ability to do that. And that's why the 5 staff found that .1 percent.
L 6 DR. WALLIS: What is a typical containment leak l 7 rate?
8 MR. SNODDERLY: They range anywhere from 3 percent
! 9 per day down to .1 for operating plants.
10 MR. GROVER: There are a large number of plants at i
11 .1 percent.
l 12- DR. WALLIS: Three percent. That must be a big 13 hole.
l _
-14 MR. SNODDEkLY: No, not really. It's --
( 15 DR. WALLIS: Not through the concrete --
16 MR. SNODDERLY: It would be -- .1 percent would be 17 a few hairs.
l 18 MR. GROVER: It's like a pencil lead. j 19 MR. SNODDERLY: And 3 percent would be -- !
20 DR. WALLIS: Where are these holes? l l
l 21 MR. SNODDERLY: They're little cracks -- they 22 could be one crack that big or a whole bunch of little 23 cracks.
24 DR. WALLIS: In concrete itself? l 25 MR. SNODDERLY. But you pump up containment to --
~
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281 1 DR. CARROLL: Or a valve.
(: ) 2 DR. WALLIS: This is based on what kind of a 3 pressure difference?
4 MR. SNODDERLY: You take the containment to 5 typically 35 to 40 pounds.
6 DR. WALLIS: Ah,.okay. So it's not just --
7 MR. SNODDERLY: Just below design.
8 DR. SEALE: It's a liner in concrete usually.
9 DR. FONTANA: You were -- kind of over your 10 objections you put in a nonsafety-grade spray system.
11 You've taken no credit at all for this?
12- MR. GROVER: No credit. That is for severe 13 accidents.
14 DR. FONTANA: It's not safety grade, so they can't
) 15 take credic.
16 DR. KRESS: In the calculation of the leak rate 17 are you still required to hold the large-break LOCA maximum l 18 pressure for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />?
l 19 MR. GROVER: For the dose analysis I did. I l
20 assumed that the containment leaked at its design rate for 21 the duration of the accident. I did not take --
22 DR. CARROLL: You are asking about the test, Tom?
23 DR. KRESS: No, the regulation. So the design l
24 leak -- the leak rate would then be at maximum design 25 pressure.
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1 282 1 MR. GROVER: Right. I'm taking no credit for any
() 2 reduction in pressure in the containment for the analysis.
3 DR. CARROLL: I do have to make my speech that it 4 is not leak rate. A leak rate is counting the number of 5 leaks that you have. It is a leakage rate.
6 DR. KRESS: It's easier to say leak.
7 DR. CARROLL: I know, but it's not proper.
8 DR. KRESS: A leak rate is how many wild onions 9 you can eat per hour.
10 [ Laughter.]
11 DR. POWERS: Do you feel like you're losing 12 control, Mr. Chairman?
13 CHAIRMAN BARTON: I think I lost it about an hour 14 ago.
) 15 DR. CARROLL: Yeah, let's get the conclusions.
16 MR. GROVER: Conclusions.
17 [ Laughter.]
18 The conclusions really go back to the previous 19 slide which related the doses, which is that we meet the
]
20 dose acceptance limits of 10 CFR 50.34 for the defined 21 fractions of that limit as provided in the standard review 22 plan.
23 DR. WALLIS: What do you mean by the most serious 24 of accidents? That's DBA, only in the design basis?
25 DR. KRESS: The most serious of the design basis )
i l
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1 283 1 accidents.
)
() 2 3
DR. WALLIS:
MR. GROVER:
Yes.
Well, I was trying to differentiate 4 between the full-dose guidelines from 50.34 and the defined 5 fractions within the standard review plan. That was the 6 attempt in this slide. So that a cories of accidents 7 considered under -- as in the grouping of design basis 8 accidents.
9 Now I was sorry in one sense to see Dr. Catton 10 leave. I believe he had a question on chi over Q. Of 11 course if he were still here this might be later at this 12 point. I don't know.
13 DR. SEALE: Almost certain.
14 MR. McINTYRE: Mr. Chairman, we have the Dudley 15 list --
16 CHAIRMAN BARTON: Yes.
17 MR. McINTYRE: That's probably not a good term for 18 it, but it's che list we get from Noel with the questions 19 that we promised. And before we -- and right now we have in 20 the room some of the resources to answer a couple of those i i
21 questions that are going to be in a car as soon as this i 22 meeting is over. And one of the ones, and I thought I had 23 Ed's name next to Jim, but he said maybe you ought to do 24 this one, is the one on -- from the third from Dana Powers, j 25 high-burnup fuel, address effects of power insertion ramp, i
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i 284 1 black and gray rad activity and iodine spiking in reactor
.; 2 coolant.
3 MR. GROVER: Well, Ed and I both looked through 4 that transcript, and anyplace we could find iodine spiking,
! 5 we couldn't find a question -- we found reference to Dr.
6 Powers' questions on spiking.
7 MR. McINTYRE: Okay, never mind. Dr. Powers.
8 DR. POWERS: Is this reactivity insertion or is it l
L 9 iodine spiking?
i 10 MR. McINTYRE: Reactivity insertion is next.
l 11 DR. POWERS: Yeah, I think the question on l
12 iodine -- on reactivity insertion was how did you do the 13 calculation.
t
! 14 MR. McINTYRE: Right, but that's him.
() 15 DR. POWERS: Oh, okay.
16 MR. McINTYRE: That's him, but --
l 17 MR. GROVER: But it was linked somehow to iodine I
18 spiking.
19 DR. POWERS: There's no linkage here. It was the l 20 question on --
21 MR. McINTYRE: Here's your question.
l 22 MR. GROVER: And the whole gray and black 23 discussion wasn't found in the whole transcript. We did a 24 word search.
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l 285 l
1 has -- on high-burnup fuel has -- he changed the spiking due
( 2 to higher inventories in the GAP for high-burnup fuels. ;
3 MR. GROVER: Do we change the spiking for I
4 high-burnup fuels? We do not -- when we were following the 5 staff's identified spiking model from, you know, the iodine
{
6 spike is supposed to relate primarily to fuel rods that are l
7 _ experiencing changes in pressure and/or power levels, and 8 we're going to see that more in the lower-burnup assemblies, 9 lower-burnup rods. I guess I'r not sure how much activity 10 is there to contribute to iodine spiking in these 11 high-burnup rods.
l 12 MR. McINTYRE: So that's a no, then, is that l 13 right?
l
, 14 DR. POWERS: Well, it seems to me that as you go 15 high burnup your decay is no longer taking place or your 16 fissioning is no longer taking place in the bulk of the
! 17 pellets, it's taking place on the surface. So you're f 18 building inventory at the surface. You have to be building 19 inventory at the surface. j 20 MR. GROVF., Is this true? Is it happening on the 21 surface?
t l 22 DR. POWERS: Sure.
l 23 MR. GROVER: I don't know.
l 24 DR. POWERS: Sure. You're building in plutonium i
L 25 on the surface. Everything's taking place at the surface i
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! l 1
286 l
1 now. As you' cross over oh,' 45,000, 50,000 megawatt days per 2 Jton you're suddenly starting to-get more buildup at the
- 3 ' surface. On top of that, the porosity of your fuel is just
'4 much higher-on the surface. You get a rim effect, okay? So 5 you've got room to accumulate this inventory.
6 Now does that change the way you analyze an iodine
( 7 spiking event, because you've just got more stuff that can 8 come.into the pool? l 9 MR. GROVER: We did not take that into
)
\
10 consideration. '
l 11 DR. KRESS: The only way you could.is to have some I
12 good data -- i 13 DR. POWERS: Yes, it seems to me you've got to t
14 have data on what the inventory is and, I mean, you've got 15 an assumption of something like five percent. I think we 16 all agree for conventional-burnup fuels --
17 DR. KRESS: That's pretty good.
f 18 DR. POWERS: Five percent must be conservative.
19 DR. KRESS: It's --
20 DR. POWERS: I mean everything that we've ever 21 done -- we -- everything that's been done at Oak Ridge by l 22 Malanoskous and co-workers says five percent is a good l l
l 23 conservative value for fuel up to about 30,000 megawatt-days j I !
24 per ton, which is the highest they measured. Okay? But now 25 you get this change in fuel structure as you cross the l l
)
(O V
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287 1 roughly 45,000, 50,000 megawatt days. And that change looks
() 2 like it leads to a higher-gap inventory.
3 DR. KRESS: I agree. Be a good subject for 4 research.
5 DR. POWERS: What we see from the Japanese data, 6 there's this nice, provocative little report. They said 7 they'had a'20-percent gap fraction on krypton. So naturally 8 you ask them what about iodine. Well, they didn't measure 9 right.
10 He has problems in the iodine spiking event.
11 MR. GROVER: I have looked at this but it was 12 awhile ago and I don't know how much -- if it was 13 differentiated between stable gases and -- you know, stable !
14 and Krypton-85, say, and the short-lived, so it wasn't clear 15 to me from looking at that --
16 DR. POWERS: Yes -- your argument that the stables 17 are what are important really works well if you having 18 fissioning taking place through the bulk of the pellet 19 because then it just takes a long time for that material to 20 move there and the shorts die out, but -- before they get to 21 the gap.
22 But now if we're talking about these epithermal 23 fissioning processes taking place because of the plutonium !
24 on the surface, now that argument doesn't buy. You are 1
25 building the inventory in right at the surface. It mean it I
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288 1 .didn't have to diffuse anywhere. In fact, you have got
() .2, essentially a foam fuel layer there where it is taking 3~ place. It is borne in the surface and the trouble is I
'4- don't have any more data on what the inventory is than 5 anybody else does.
6 Fortunately, I suppose you could build your plant 7 and run it for four cycles before you have to worry about 8 this problem.
9 MR. GROVER: And there is a lot of margin, 10 MR. McINTYRE: The second question is the -- it is 11 written =out as a subcommittee question but it was, Dr.
12 Powers, your question was the one on the heat-up rates --
13 two down from the one we just answered.
14 [ Pause.]
() 15 DR. POWERS: The question there really turns on-16 the beta factor that'you use in the rod ejection 17 calculations.
18 MR. CARLIN: The beta we are using there is the --
19 you take the as-calculated beta factor -- this is Ed Carlin.
20 The beta factor we are going to use is you take 21 the calculated value and then put standard nuclear design 22 uncertainties on it and you would use for any other core 23 physics parameter.
24 DR. POWERS: And you don't put a bias on it?
I don't quite know what you mean by a
.i 25 MR. CARLIN:
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2 DR. POWERS: Jack it up by 5 percent.
3 DR. CARROLL: That is what his uncertainty factor
!. 4' is.
l l 5 DR. POWERS: Okay, so your uncertainties all go i
6' one way?
7 [ Pause .~)
! 8 DR. POWERS: The question then comes in that when 9 have these gray rods in the core, do you have a different
'10 reactivity problem with the gray. rods when you have a gray 11 rod adjacent to high burnup assembly which is surrounded by 12 low burnup assemblies?
l 13 MR. CARLIN: I can't answer that but the way we l
l- _
14 are doing the rod ejection transients, we could take the 3-D
'O) l(_
i-15 core design code they are going to use to design the core
) 16. with and we look at every rod. No matter what it is, they 17 are going to-pull'it out.
L 18 First, we do a static. We'try it out, see how 19' much it is worth, see how much the peaking factor changes, j 20 and then after you have looked at every rod, when we get to 21 do the transient analysis, you go and you take the highest 22- peaking factor and the highest reactivity worth and then you 23 use that in'the transient analysis.
24 DR. POWERS: I guess what I am asking is when you 25- go'through that process the' gray rods are looked at.
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l 1 MR. CARLIN: Right. Every rod is looked at.
l
( 2 DR. POWERS: I think that was the question that I 3 was posing. It was whether the gray rods were examined in 4 that process. I
_5 MR. .CARLIN: Any rod that could be in the core and l '
6 'could be ejected is examined.
7 DR. POWERS: And you looked at assemblies with ,
8 burnups that went to what?
9 MR. CARLIN: Whatever the design is for this plant 10 with the 24-month cycles.
11 DR. POWERS: For just the 24 month cycle or did 12- you go to --
13 ;MR. CARLIN: The analysis we are doing is covering 14- 18 and 24 month cycles and it is covering the first cycles
()
15 and an equilibrium cycle also.
16 DR. POWERS: An equilibrium cycle, which would be 17 like 33,000?
18 MR. WINTERS: We don't have that number for 19 burnup.
20 DR. POWERS: It can be relatively important when 21 you have heterogeneous cores here where you have high burnup 22 assemblies and you have lower burnup assemblies. Those are 23 when you get really bad situations on the power 24 introductions.
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291 1 under-predict the power _ deposition.
MR. McINTYRE:
([ ?2 That's it.
3 MR. GROVER: Oh, I was just going to add the one 4 thing on the Chi over Q,.because I believe the question was 5 _. did we consider inversions and that kind'of-thing.in the two 6 hour Chi over Q; 7 ~The Chi over Q is reflective of the meteorologies l 1
8 that-were calculated for a large number of plants; and this 9 was bounding, you know, and each.one of those' considered a 10 year or more of meteorological data, so they would have 11- included these' periods of low wind speed and it is like Mr.
12- Emch has talked about. We talked about 95th percentile on 13 Chi ~over Q or fifth percentile.
14 DR. POWERS: I don't think that addresses the f 15 . question that Ivan had, does it?
16 DR. KRESS: I don't think it was' exactly the .
l 17 question, i
18 DR. FONTANA: I think he said there were cases !
)
19 where.he's seen perfectly acceptable Chi over Qs and .I 20 . unacceptable downstream behavior because of the inversions 21 and looping and stuff like that.
22 MR. McINTYRE: I think the real answer to that is
~23 going to be that when you go to site the-plant that you have 24 to look at those sorts of things and that is not something 25 that we are going to look at here at the design 1
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292 1 certification.
() 2 3
DR. KRESS:
MR. McINTYRE:
It will be up-to the siting --
Sure.
4 DR. SEALE: Yes.
5 MR'. McINTYRE: They have to make sure.it fits on 6 'that site'and Rich is going to have to check them real-7 close.
8 MR. EMCH: Yes. That is a COL action item.
9 CHAIRMAN BARTON: Since it is 3 o' clock, does the 10 Staff now have any comments on Chapter 15?
11 MR. EMCH: No.
12 [ Laughter.]
13 CHAIRMAN BARTON: Before we recess until tomorrow, 14 there's --
!(O,/
f 15 DR. WALLIS: Mr. Chairman?
16 CHAIRMAN BARTON: Does the Staff have any open i i
17 items on this chapter? '
. 18 MR. EMCH: No.
t 19 CHAIRMAN BARTON: Comment? Question? j 20 DR. WALLIS: Well, I'm new to the process here and '
21 I see a fat document here submitted by Westinghouse and I L 22 see a thin document which I am not allowed to refer to in 23 draft form prepared by the Staff.
24 The thin document looks like an abbreviated 25 version of this one. It is as if someone has gone through h
A/
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l 293 1 here and put it into shorter and more understandable I I~ 2 ~English.
b-3- But where is the critique or where is the 1 4 evaluation that says that this is right? You say it is 5 acceptable based on --
i
- 6. MR. CARUSO: In evaluating what is in the thick i 7 document, the Staff uses another document which is not as !
8 thick called the Standard Review Plan.
9 DR. WALLIS: It is a check-off?
10 MR. CARUSO: It is not a check-off in the sense 11 that you just check things off, but it provides acceptance 12 criteria and issues that the Staff should consider as it j 13 reviews the Safety Analysis Report, l
l 14 The Safety Evaluation Report-that you have is a 15 summary of.the Staff's thought processes as they have 16 reviewed the SAR and I certainly hope that it contains an 17 explanation of why the Staff found the analyses acceptable.
18 It is supposed to be included. That's the way we I l 19 wrote it.
20 DR. WALLIS: Well, it doesn't give me the l 21 impression that you have challenged the analyses by doing, 22 .say, your own analyses or saying what happens if another i
23 assumption is made than was made by Westinghouse, or all the I 24 kinds of things that a professor might do.
25 DR. CARROLL: Seventy-five-hundred requests for l
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l 294 1 information.
() 2 3
DR. WALLIS:
' thin document.
It is not reflected in this, in the i
The thin document is sort.of saying, well, 4 it summarizes what it is in here and says it is okay.
5 MR. CARUSO: Yes, and there is -- 1 6: DR. WALLIS: It doesn't say we have really l 7 challenged it by making our own analysis'of this and we, 8 having put it to the test, here's the kind of comparisons-we l 9 make and, therefore, we conclude it is okay.
10 MR. CARUSO: Well, as I said earlier, the staff 11 makes it determination about the acceptability of the design
. :02 based on what is in here, what is in the safety analysis.
13 report. The staff does not --
14 DR. WALLIS: That's all that is used?
() 15 MR. CARUSO: That's all we are allowed to use.
16- DR. WALLIS: Well, that's crazy, Because it-might 17 well be that somebody using,-RES has RELAP and --
18 MR. CARUSO: NRR has RELAP also.
19 DR. WALLIS: Well, it would seem if you have i
l 20 RELAP, you should use it to run the same kind of scenarios l 21 that they use.
l \
! 22 MR. CARUSO: And indeed we do, and indeed we have. !
23 DR. WALLIS: That is not recorded at all in this 24 thin document.
25 .MR. CARUSO: We use them, but those analyses are f
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295 1 used to confirm decisions which are made on the basis of f
r3 6 2 what is in the safety analysis report itself. Because the J
3 safety analysis report is what is available to the public.
4 DR. WALLIS: There is no check that what 5 Westinghouse actually calculated was correct.
6 MR. CARUSO: I don't think I would say that 7 because we have done calculations of a lot of these 8 different transients using RELAP, using TRAC, using our own 9 methodologies. And based on our experience with other 10 reactors that exhibit similar phenomena, and based on our 11 engineering knowledge and understanding of the plant, that 12 goes into making the determination that these analyses here l
13 are acceptable.
14 DR. FONTANA: I think Professor Wallis' point is l O 15
(_,/ that we have to take your word for it.
16 DR. WALLIS: That makes me uncomfortable. We sort 17 of take your word for it that you have thoroughly challenged 18 their --
19 MR. CARUSO: The problem is -- there is what is in 20 the SAR, there is what is in the SER, S-E-R, and there is, 21 as was said before, a large number of questions and 22 responses by Westinghouse. Okay. And those questions and 23 answers and the discussion between the staff and 24 Westinghouse to resolve those questions are what has led the l
l 25 staff to the conclusion that the SAR is acceptable. And
!n
\-s 4
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296 1 those questions and answers are all documented and they are
- p)
'q )
2 on the docket. They are not in the SAR, I don't believe, 3 but they are on the public docket.
4 DR. WALLIS: So what is the SAR is being 5 considerably influenced by your doing independent analyses 6 to check the believability of Westinghouse's and this has 7 often resulted in Westinghouse, therefore, changing their 8 analysis?
9 MR. CARUSO: Challenging analyses, doing 10 additional analyses, changing assumptions and doing 11 sensitivity runs. The most recent example I can think of 12 that is ATWS calculations, where we had a number of 13 questions about ATWS assumptions and we required them to do 14 a whole series of sensitivity runs.
(^)x
(_ 15 DR. WALLIS: There is a huge amount of work that 16 you have done which isn't then available to the ACRS to 17 evaluate? We just have to take your word for it, as my
)
18 colleague says. I 19 MR. CARUSO: Well, it is available in the sense 20 that these questions and answers have all been provided to 21 the ACRS, I believe, as part of the normal docketing 22 process.
23 DR. WALLIS: But it doesn't -- it doesn't help 24 someone like me to say -- the key issue with this particular 25 event was this, this and this, and this is how it is I
,~.
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297 1- resolved. It simply goes through and says it is acceptable.
im I
J 2 Whereas, I don't see a sort of logical train or something I 3 can follow there or --
4 MR. CARUSO: I guess I would say it is unfortunate 5 that we have an SAR and we have now seven years of questions 6 and answers and discussions, and it is difficult to distill 7 that into something that is easily understandable for a {
8 layman or a knowledgeable technical person who doesn't --
9 who hasn't been a part of the process over the past seven 10 years. That's unfortunate. I don't know how to fix that.
11 DR. WALLIS: Well, it would -- this isn't the way 12 it is done, but it would help me if there were some sort of 13 history that said that this was how we arrived at this, this 14 is the process historically through which we arrived at the
)
()/
s, 15 conclusion that this acceptable,
\
l 16 Now, maybe you can't do that legally, but I have i 17 seen in the case of staff analyses, predictions of, say, 18 data from a facility which were way off, and then people 19 worked very, very hard to fix it up. All that history is 20 important in assessing how good the final conclusion is.
21 But that is all lost in what you present to us.
22 MR. CARUSO: I don't know how to respond to that 23 except to say that there has been a tremendous amount of I
24 discussion back and forth. Analyses have been done, I'
25 re-done, have multiplied. The design of the plant has l
l I
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I 298 ;
1 1 changed a lot, I Clink, personally, in a number of I
(";
v 2 significant ways over the past seven years as a result of l 3 this discussion that has gone on. !
4 DR. FONTANA: Are the NRC calculations -- excuse 1
5 me.
6 MR. CARUSO: Dr. Kenyon -- I'm sorry. Excuse me.
7 DR. FONTANA: I was saying are the calculations 8 that NRC has done, are they documented and available to 9 someone who wants to audit them?
10 MR. CARUSO: Well, the Committee has seen a lot of 11 the calculations that have been performed by the Office of 12 Research. NRR has done a lot of calculations which we don't 13 armally provide to the ACRS. They are kept internally for 14 our use.
f'N
( ,) 15 MR. KENYON: This is Tom Kenyon. I have been the 1
16 project manager on the AP600 actually since 1992 when I made 17 the submittal. There is some limited documentation of the 18 issues that were raised by the staff. In November '94, we i
19 issued a draft SER that contained about 1200 open items, and 20 in the spring of '96 we issued -- also issued a supplement 21 to that document that talked about the testing and code 22 programs that contained an additional 120 items.
23 Now, part of our legal requirements is, because we 24 have gone into public domain, we need to address how those 25 draft SER open items have been addressed. So, as you go O ANN RILEY & ASSOCIATES, LTD.
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l 299 1 through the document, you will.see references to DSER open 2 items that says, you know, -- I'll give you an example.
3 We raised a concern about'the -- you'll go through 4 and it'll say in the draft SER, the staff raised an issue 5 concerning the Ph control, for instance. And it will tell 6 you that, you know, Westinghouse addressed the concern by, 7 you know, providing these baskets as we talked about earlier 8 today.
9 It will say that the staff has reviewed it and 10 determined it to be acceptable for a number of reasons. And 11 those reasons could be as simple as that they comply with
'12 what is laid out in the SRP. They demonstrate, confirm --
13 they demonstrate that they comply with the regulations, that 14 sort of thing.
15 DR. WALLIS: I guess what concerns me is more at a l 16 different level. If I have two students who do a model of, 1
17 say, some fluid dynamics using CFD, using some commercial '
18 code, PHOENIX or something, they come back with completely 19 different answers. They have used an acceptable code, it 20 may have been blessed by the NRC, but it gets different 21 answers, because there is a user dependence. And, also, i
22 there are different codes. There's RELAP and this one here. 1 23 The fact that they have used a good code that has 24 got your blessing doesn't mean that the results are robust 25 when tested against user dependence or against the use of a i
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73
(
%J
) 2 MR. EMCH: I think we said earlier that we do a 3 fair amount of confirmatory analysis. I mean you're right, 4 there ic -
5 DR. WALLIS: That isn't revealed in any of the 6 words in this thin document.
7 MR. EMCH: I thought that we said that, that we 8 did confirmatory analysis, at least in the dose assessment 9 area.
10 MR. CARUSO: I know we did confirmatory analyses 11 in the case of ATWS, it was.one of the very first.
12 DR. WALLIS: But you don't supply one to one 13 correspondence where there is this -- and you can figure 14 out, --
13
' \,,_) 15 MR. CARUSO: No. j 1
16 DR. WALLIS: Here I can rip out and say the NRC I i
17 one looks the same.
18 MR. CARUSO: No, we do not do that because that 19 would -- that would imply that an NRC analyses formed the 20 basis for a decision that we made, and that is not -- we are 21 now allowed to do that.
22 DR. WALLIS: That's strange.
23 MR. CARUSO: You have to realize that the legal 24 environment in which we work is that the licensee has the 25 burden of proof -- and I am sorry to say this, I hate to get l
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301
'l into this, the licensee, the applicant, Westinghouse in this 2 case, has the burden of proof of showing that the design is 3 safe. The staff uses its independent calculations to 4 confirm that the licensee's calculations are acceptable.
5- We also do audits of licensee calculations. We l 6 had a team go to Westinghouse last fall and inspect their 7 audit calculations. They identified a number of 8 shortcomings and they are being addressed by Westinghouse.
9 We also use our knowledge and experience as engineers in 10 this field to determine whether the analyses that are 11 performed are reasonable, because very often, as you say, we 1
- 12 people who do the same calculation with two codes and we get 13 different answers.
1
, 14 I know for a fact that we have done calculations 15 of the same transient using the RELAP and TRAC codes, and 16 they have come to different answers and we work to try to 17- . understand why that is. And very often it is based on the 18 experience of the users.
19 MR. EMCH: Just as an example, in dose analysis, 20 okay, when.they do 50.59 analyses to determine if there's a i 21 USQ or whatever or anything that they do, they're using the 22 licensee, or in this case well I'll just say the licensee 23 uses their design analyses calculations and they make their 24 decisions about what's a USQ or what's acceptable and 25 everything about the responsibility for running the plant O ANN RILEY & ASSOCIATES, LTD.
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302 1 and doing -- maintaining the plant safe is theirs, and so
() 2 they use their calculations.
3 And so what we have to do is we have to work 4 through these kinds of reviews. We have to work with them 5 until their stuff is close enough for us to say it's good 6 enough, because they're the ones who are going to be making 7 the decisions on a day-to-day basis of what they're using.
8 They're not going to use the staff's calculations to make 9 their conclusions later on, they're going to use their 10 calculations, and they're going to adjust their calculations 11 when something needs to be adjusted.
12 And just looking at it, the project manager just 13 put it in front of me, we do, at least in the dose 14 ' consequence area, we do indicate that we use confirmatory O
\ ,) 15 analysis. We do indicate we do put in some tables of 16 information that were used, assumptions that were used in 17 the calculations.
18 It's still a summary of sorts, you're right. And 19 I don't know, I guess probably if the SER really laid out 20 the whole story of the review, it would be as big as the 21 FSAR.
22 DR. WALLIS: I think for this committee which sees 23 all kinds of curves and wiggles here submitted by 24 Westinghouse has no way of telling if they're realistic or 25 not except that you guys have reviewed them and think O ANN RILEY & ASSOCIATES, LTD.
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i 303 1 they're all right. That's -- so what basis do we have for 2 recommending anything to anybody except simply saying we've 3 listened to Westinghouse present pictures and you guys think- '
4 they're okay?
j l 5 DR. CARROLL: You've got to understand, Graham, i
i l 6 that the things you're concerned about have been very 1
I 7 thoroughly reviewed by the Thermal-Hydraulics Subcommittee.
8 DR. WALLIS: Okay. So --
- l. 9 DR. FONTANA: The depth was in just certain areas.
10 DR. CARROLL: Yes, but, you know, hopefully enough 11 so that you have confidence in the results of Westinghouse's 12 presenting.
l 13 DR. FONTANA: But there's a question of 14 documentation here.
15 DR. CARROLL: Well, I know that.
16 CHAIRMAN BARTON: I don't know how to solve your.
17 problem. I think this is the process that the staff's got 18 to live with. It's the process that was used to certify --
19 DR. WALLIS: I understand. I was just trying --
20 CHAIRMAN BARTON: The other two reactor --
21 DR. WALLIS: I'm trying to learn for myself of 22 being new to this game what it is, and I'm learning all the 23 time, but the process as'I've seen it so far is not 24 transparent enough to me for me to say that I have a great 25 feeling that it's -- everything is fine and dandy. I don't i
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.304 i
1 know that it's wrong either. I just feel very uncertain.
l
() 2 CHAIRMAN BARTON: I think it's the same with any 3 applicant or any licensee's application to the Commission --
4 to the staff for review of a technical tech spec change or 1 5 something. They do the work. They do the calculations.
l 6 They do the research, submit it to the staff. The staff 7 looks at it, questions the hell out of it for 2-1/2 years in 8 a simple change, and then comes out and says we finally 9 agree, we think that the applicant's change for a tech spec 10 request or request for a tech spec change makes sense, and 11 go implement it and in addition to that go do these other 12 things to give us assurance that you're going to follow up 13 and close the loop, et cetera, et cetera. I mean, that's 14 the whole process.
() 15 DR. CARROLL: Except 2-1/2 years later you forgot 16 why you asked --
l 17 CHAIRMAN BARTON: That's beside the point. But l 18 that's the process that we have to live with whether we're 19 certifying a new reactor or whether we're putting an 20 amendment in for license change or whatever. I don't know 21 what else to do with it.
22 DR. FONTANA: What you're really saying is that 23 truth is whatever the NRC says it is.
24 DR. KRESS: No, we hope to have enough l
l l 25 subcommittee meetings on things like thermal-hydraulics, I 1
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305 1 like severe accidents, like PRA, like plant operations, so
()
2 that we at least have an audit function that we can say 3 we've looked at-at least a portion of this and -- go ahead.
4 DR. FONTANA: I was-going to say how can a new guy 5 come in and follow the paper trail --
6 DR. KRESS: He can't.
7 DR. FONTANA: Documentation, references, and --
8 DR. KRESS: He can't, and he's got a legitimate --
9 DR. SEALE: Presumably that's one reason that we 10 all don't start the terms at the same time.
11 CHAIRMAN BARTON: And end at the same time.
12 MR. DUDLEY: I would like to add that the 13 Committee has already looked at the AP600 design and issued 14 four letters or five letters up to this point. In one case 15 the Committee looked at 15 major technical and policy issues ;
16 and listened to two sides, Westinghouse's and the staff's, 17 and reached a decision on the validity of the staff's --
18 DR. WALLIS: Oh, so they do actually get to 19 adjudicate between two sides with different views?
20 MR. DUDLEY: Yes.
21 DR. CARROLL: We make a recommendation.
22 DR. POWERS: Yes, we never adjudicate.
23 DR. WALLIS: Because these two documents seem to ;
24 be two sides who agree on everything. So what are we here l
25 for if we just agree on everything? ;
I l
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306 1 DR. KRESS: If they didn't agree they would go
() 2 3
back and do a lot more work until they did.
DR. WALLIS: We only have work to do if you 4 disagree.
5 DR. CARROLL: No , no. I think we are looking for 6 ' issues that may have dropped through the cracks, and I can 7 think of many of them on the two evolutionary plants we came 8 up with that ultimately got resolved to our satisfaction.
9 DR. POWERS: And I suspect we'll be pursuing 1
10 reactivity insertion accidents a little further here too.
11 MR. DUDLEY: I think a perfect example is the 12 Committee was requested to review whether a core spray was 13 necessary for the AP600, and that's a significant design 14 change.to the plant.
) 15 DR. KRESS: Core spray?
16 CHAIRMAN BARTON: Containment.
17 DR. KRESS: Yes, I didn't recall the core spray, 18 CHAIRMAN BARTON: That was the other reactor.
19 Might need that one --
20 DR. SEALE: Boy, that would set them back a little 21 ways.
22 DR. POWERS: How about putting a suppression pool 23 out there?
24 CHAIRMAN BARTON: Before we get completely out of 25 control, we intend'to put out a report at the full Committee O' ANN RILEY & ASSOCIATES, LTD.
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307 1 meeting later this week based on today's presentations and
() 2 also the topics we'll be discussing tomorrow, so I think we 3 need -- what we need to think about anything that we heard 4 today or didn't hear that we would like to have Westinghouse 5 or the staff address at the full Committee meeting, because 6 they are on the agenda for full Committee meeting on 7 Wednesday, Thursday, I forget which day it is.
8 So overnight think about those issues that you'd
( 9 like to hear from Westinghouse or the staff at the full 10 Committee meeting, and any questions or comments that you've i
11 got, please get them to Noel that would go into the 12 preparation of the draft report that we will put out later 13 in the week, and we already got some comments from Ivan, who 14 had to leave us for food for thought for the letter. And
- l ("
15 Jay, are you going to be here the rest of the week?
16 DR. CARROLL: No , just tell --
i 17 CHAIRMAN BARTON: Okay. So if you leave before we 18 get to the letter-writing, please get your notes or comments 19 to him. Okay.
20 Are there any other questions, comments before we 1
21 recess till tomorrow?
22 DR. SEALE: I'd just like to remind Tom and Dana l
23 _that we probably will have a Planning and Procedures meeting i 24 af ter the subcommittee adjourns tomorrow af ternoon.
I 25 DR. POWERS: Just in case you were planning on '
j
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1 308 1 wild partying.
ID ~2 DR. KRESS: I think we were planning on doing a V -
-3 rehearsal for --
4 CHAIRMAN BARTON: We need to do some Commissioner 5 rehearsal, there's several of the items on there that's a 6 John and Tom act, et cetera, so we need to kind of go 7 through and reJearse, and I think there's some time on the 8 main Committee agenda, but it's just before we have to tromp 9 over to the other building. So maybe we want to spend some 10 time tomorrow afternoon going through that session.
11 DR. KRESS: Which means we need to expedite the 12 P&P meeting.
13 DR. CARROLL: You got Sam back. That ought to 14 expedite things. He always takes just a few minutes to go
(/ 15 through --
16 [ Laughter.]
17 CHAIRMAN BARTON: Anything else we want to add to 18 this evening?
19 If not, we'll recess till tomorrow at 8:30.
20 [Whereupon, at 5:58 p.m., the hearing was 21 recessed, to reconvene at 8:30 a.m., Wednesday, April 1, 22 1998.]
l 23 1 24 25 I T ANN RILEY & ASSOCIATES, LTD.
\- / Court Reporters l 1250 I Street, N.W., Suite 300 i Washington, D.C. 20005 (202) 842-0034
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PLACE OF PROCEEDING: Rockville, MD were held as herein appears, and that this is the original transcript thereof for the file of the United States Nuclear Regulatory Commission taken by me and thereafter reduced to typewriting by me or under the direction of the court reporting company, and that the transcript is a true and accurate record of the foregoing prcceedings.
1'I w A, ii
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