ML20216F265
| ML20216F265 | |
| Person / Time | |
|---|---|
| Issue date: | 09/15/1999 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| ACRS-T-3088, NUDOCS 9909210227 | |
| Download: ML20216F265 (524) | |
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ovo a ACRsp So88 l ] OFFICIAL TRAN CRIPT bF PROCEEDINGS NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS
Title:
MEETING: TIIERMAL-IIYDRAULIC PHENOMENA TRO4 (ACRS' RETURN ORIGINAL TO bJh"ri!TE , M/S T-2E26 , . . , . 415-7130 ' THANKS! D Docket No.: I Work Ordr No.: ASB-300-919 9909210227 990915 088 PDR ! LOCATION: Rockville,MD I 1 DATE: Wednesday, September 15,1999 PAGES:1 - 382 l l l ANN RlLEY & ASSOCIATES, LTD.
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E ii N I A lb l l DISCLAIMER l l UNITED STATES NUCLEAR REGULATORY COMMISSION'S ADVISORY COMMITTEE ON REACTOR SAFEGUARDS l 1 SEPTEMBER 15, 1999 , 1 The contents of this transcript of the proceeding of the United States Nuclear Regulatory Commission Advisory Committee on Reactor Safeguards, taken on September 15, 1999, as reported herein, is a record of.the discussions recorded at the meeting held on the above date. l This transcript had not been reviewed, corrected
.and edited and it may contain inaccuracies.
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1 1 UNITED STATES OF AMERICA () 2 3 NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 4 5 *** 6 7 MEETING: THERMAL-HYDRAULIC PHENOMENA 8 9 10 U.S. N.R.C. 11 Two WhiteFlint North, Room T2-B1 12 11545 Rockville Pike 13 Rockville, Md 14
) 15 Wednesday, September 15, 1999 16 17 The committee met, pursuant to notice, at 8:30 18 a.m.
19 20 MEMBERS PRESENT: 21 GRAHAM WALLIS, Chairman, ACRS 22 THOMAS KRESS, Member,- ACRS 23 DANA POWERS, Member, ACRS 24-
. 25 ANN RILEY & ASSOCIATES, LTD. ~ \_e_ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l
2 1 P R O-C E E D I N G S () 2 3 CHAIRMAN WALLIS: [8:30 a.m.) The meeting will now come to 4 order. This is a meeting of the ACRS Subcommittee on 5 Thermal-Hydraulic Phenomena. I'm Graham Wallis, the 6 Chairman of the Subcommittee. 7 The ACRS members in attendance are Dr. Thomas 8 Kress and Dr. Dana Powers. The ACRS Consultant in 9 attendance is Professor Virgil Schrock. 10 The purpose of this meeting is to review the 11 proposed resolution of Generic Safety Issue 23, Reactor 12 Coolant Pump Seal Failures, and continue the subcommittee's 13 review of the NRC Office of Nuclear Regulatory Research's
- 14. thermal-hydraulic research program, including its plan for
() 15 consolidating thermal-hydraulic codes. 16 The subcommittee will gather information, analyze 17 ' relevant issues and facts, and formulate proposed positions 18- and actions, as appropriate, for deliberation by the full 19 committee. 20 Mr. Paul Boehnert is the Cognizant ACRS Staff
'21 Engineer for this meeting.
1 22 The rules for participation in today's meeting 23 have been announced as part of the notice of this meeting 24- previously published in the Federal Register on August 31, 25 1999. O \/ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
3 1 A transcript of this meeting is being kept and () 2 3 will be made available as stated in the Federal Register
. notice.
'4 It is requested that speakers first identify 5 themselves and speak with sufficient clarity and volume so 6' that they can be readily heard.
7 We have received no written comments or requests 8 for time to make oral statements from members of the public. 9 We will now proceed with this meeting and I will 10 call upon Mr. Sher Bahadur of the NRC staff to begin. I 11 note that he has a lot of slides, with a great deal of 12 technical information that I'm looking forward to. 13 MR. BAHADUR: Good morning. I'm Sher Bahadur, the 14 Branch Chief in the Division of Engineering Technology, the () 15 Office of Research, and I have the lead responsibility for 16 the closure of GSI-23. 17 We have sent a closecut memo for review to the 18 subcommittee.about two weeks back and the presentation will 19 summarize the information that we have given in the closecut 20 memo, 21 What I plan to do is -- 22 CHAIRMAN WALLIS: Excuse me. I hate to interrupt. 23 The memo that I got was all regulatory stuff, redefining the 24 problems that went away, and your slides are all technical. 25 So I'm interested in the contrast.
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4 1 MR. BAHADUR: Let me just explain that to you, f') 2 just.how and why I have designed this presentation the way I V 3 have. 4 As you will see, this presentation will be shared 5 by a number of people. Let me introduce them to the 6 committee. 7 I have Jerry Jackson with me. Jerry Jackson is 8 the Project Manager in the Engineering Research Applications 9 Branch, the branch that is responsible for GSI-23. While we 1 10 were working on this particular GSI, we took the assistants 11 from a sister division within the Office of Research. I 12 have Mark Cunningham, who is the Branch Chief in the 13 Division of Risk Assessment and Applications, and with him I 14 is Art Buslik, who is the Project Manager for the risk 15 studies. 16 The memo that you got is the memo that summarizes 17 the basis on which the staff has made recommendations to 18 close out the GSI-23. But when we were designing this 19 presentation, we thought it would be worth our while to go 20 back and look at the technical issue which is faced in the 21 GSI-23. 22 This has been with us for a long, long time and 23 one of the thinkings was that we would use this presentation 24 to go back and see what the technical issues are and what 25 kind of work the staff nas been doing from '70s and 80's on [ ) ANN RILEY & ASSOCIATES, LTD. \/
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5 l i 1 to today, and then present to you the information based on I g 2 which a cautious decision'has been made to close out the 3 GSI-23'. 4- .Of course, the design of this presentation is very 5 modular. It's been made in a way that if the subcommittee 6 wishes _we go much in detail on a particular aspect, we will ) 7 do that. If you believe that that information is not needed 8 this morning, we can just accelerate that and move to the I
-9 .next topic.
10 With that in mind, let me introduce the agenda 11 that we plan to use this morning. The first part of the 12 presentation will be where Jerry Jackson will give, in 13 detail, the technical issues related to GSI-23. He is 14 prepared to speak in detail about the RCP operations, 15 material types and, also, the plant usage. But as I said 16 before, if the subcommittee decides that we don't need to go . 1 17 that i much in detail, we can use that as background ) 18 information and move on. 19 He will also summarize the history of the staff
;20- action from the '70s and '80s till today, because the staff 21' has produced a large number of work during that period.
22- As we move on from the background, we go into the I 23 staff actions. We have done some work on the degradation of
-24 -polymer seals, conditions under which the polymer seals l
25 -would experience extrusion, and then the loss of cooling O O ANN RILEY & ASSOCIATES, LTD. Court Reporters ! 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 , (202) 842-0034 i
l 6 1 ' conditions. So we will summarize all that work and then, of (f '2 course, the research also addressed the conditions in which
'3 the seals will become unstable.
4 The. staff has done a lot of work in the I 5 development of the Rhodes model. We will summarize that for !
'6' you. And as you are aware, all this work was culminated
'7 into a proposed rule that went to the Commission in 1995.
8 Of course, the Commission, at that time, found insufficient 9 basis for gains in safety and, therefore, disapproved that 10 proposed rule. 11 Most recently, we have done some plant-specific 12 1 studies on the station blackout analysis. We have also j 13 looked at the risk significance of RCP failures caused by
-14 the failure of component. cooling water and the emergency 15 service water systems.
16 Mark Cunningham will summarize that work and then 17 Art Buslik will give yoi idetails of those two analyses that 18 we have done. 19- Jerry Jackson will then come back and summarize 20 .the factors based on which we are recommending that the GSI 21 be closed and I have listed them out here, but I don't need 22 to. read them line-by-line, as you will hear about those in 1 23 detail in Jerry Jackson's presentation. J 24 DR. SCHROCK: Does this' depend a lot on this ! 125 Rhodes model? I ANN.RILEY & ASSOCIATES, LTD. l I\ >) Court Reporters 1 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 i (202) 842-0034 I
1 7 1 MR. BAHADUR: The transient? () 2 3 DR. SCHROCK: The reason I ask is that I'm unfamiliar with.it and'if it depends quite a bit on it, I'd 4 like to hear the essence of the model. We will hear that? I 5 MR. BAHADUR: We will make sure that the 1 6 presentation includes details of the Rhodes model as that. 1 7 DR. SCHROCK: Thank you, l 8 MR. BAHADUR: .Having summarized all the factors 9 which we have been considering for the clcsure, we will move 10 to the next item, and that will'be the future RCP seal 11' ~ activities. 12' While the staff is recommending closure of GSI-13 23, we recognize that further work needs to be done before I 14 this' issue can be completely addressed on a plant-specific 15 basis. 16 -CHAIRMAN WALLIS: I understand from the document
. 17 you sent us that there is nothing in the budget for these 18 improved RCP seal models.
19 MR. BAHADUR: That is very true, and what you will 20 hear will be the approach that the staff had taken to 21 address the development of these models in concert with the
'22 industry, talking to EPRI and also making sure that the 23- -standard development takes into account some of these 24' -models. You will hear about that when we talk about these 25 future activities.
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8 ! I 1 So with that as an introduction of the agenda that p 2 we plan to follow this morning, if the subcommittee doesn't (% )) 3 have any questions or concern about this agenda or have 4 suggestions to change the order, I would like to present 5 Jerry Jackson. 6 CHAIRMAN WALLIS: Please do. i 1 7 Mr BAHADUR: Jerry? 8 MR. JERRY JACKSON: Jerry Jackson, from Office of 9 Research. 10 I just wanted to say, first of all, that I don't 11 believe resolution of this issue is really based on the 12 Rhodes model. Some of the analysis used the Rhodes model, 13 but that's not the basis of the closure of the issue. 14 I was asked to go over a bit of the backgrcund of 15 this issue, since it's been around for a number of years. 16 So I'll try to go fairly rapidly. 17 The technical issue that remains really deals with 18 the loss, complete loss of seal cooling, when you don't have 19 sufficient makeup capability or ECCS to make up for that, 20 and this can result from -- mainly from station blackout. 21 That's one of the main concerns, but also we've identified 22 another risk that can result in the same scenario, and 23 that's the loss of component cooling water. 24 For most of the seals, we'll explain later how 25 thermal barrier cooling in some of the seals have injection 1
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9 1 pools. So if you lose component cooling water, you can lose () 2 cooling to the thermal barrier, which cools the seals, and 3 also the component cooling water is involved in cooling the 4 injection pumps that supply the injection cooling to the 5 seals. So loss of component cooling water can disable the 6 cooling system with seals, as well. 7 And, of course, loss of essential service water 8 supports. component cooling water and it also, in some cases, 9 cools the injection pump. So you can lose cooling by that 10 method. 11 The earlier technical issue that this Generic 12 Issue 23 was really predicated on initially was a large 13 nutdoer of normal operation f ailures; that is, failures that 14 didn't involve loss of cooling, but just failure during 15 normal plant operation. 16 CHAIRMAN WALLIS: How many failures were there? 17 What's a large number? 18 MR. JERRY JACKSON: A large number, they exceeded 19 the-frequency for small break LOCAs by an order of 20 magnitude, that was assumed in WASH-1400. 21 CHAIRMAN WALLIS: That's theoretical. Oh, the 22 actual. 23 MR. JERRY JACKSON: These came from actual events. 24 CHAIRMAN WALLIS: That's a pretty low frequency, 25 too, isn't it? It exceeded ten-to-the-minus-two? O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 ; (202) 842-0034 l
i 10 1 MR. JERRY JACKSON: I think ten-to-the-minus-two ( 2 was the number. Ten-to-the-minus-three was actual. 3 CHAIRMAN WALLIS: So large number means a few a 4 year or something? 5 MR. JERRY JACKSON: Let me express it a different 6 way. The way that I remember it was about three percent of 7 the industry downtime was due to seal failure; in other 8 words, three percent of the operating downtime came from 9 seal failure. So I would consider that a fairly large 11'O number. 11 Some of those leaks were quite large. I remember 12 the H.B. Robinson, it was estimated that the leak rate for 13 that was 500 gallons per minute. There were some other 14 events, like Ginna-02, I believe, that was over 200 gallons () 15 per. minute. I believe that's the correct plant. And there 16 were some others. l 17 So there were some fairly large leaks that l 18 happened during that time. I 19 CHAIRMAN WALLIS: Then they improved reliability. 20 What's the measure of that? 21 MR. JERRY JACKSON: The number of failures that 22 occur today. That has been reduced significantly. 23 CHAIRMAN WALLIS: Is it now zero or is it one or 24 two a year or what is it? 25 MR. JERRY JACKSON: I would characterize it as
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11 1 very few events. Just one or two events that might affect 2 operation of the plant, but no large failure that result in
,3 any large leak rate. There is always problems that occur 4 with the seal, but sometimes they are taken care of in the 5 next outage, et cetera, but they really don't require the 6 plant to shut down that often.
7 CHAIRMAN WALLIS: It would be useful, when we have 8 these qualitative statements, if you just had a table that 9 showed there were so many in 1971 or something and the leak
- 10. rates. We could then see how things have gone and what you 11 mean by improved reliability and so on.
12 MR. JERRY JACKSON: We could have done that. We 13 -were giving this as a matter of background. This really 14 came up as part of the rule that was predicated back in '91 15 and it was-the CRGR eliminated this as a concern. It didn't 16 make it as far as the rule. So we kind of thought this was ' 17 not an issue anymore in that light.
~
18 CHAIRMAN WALLIS: Well, this is real evidence. 19 This is not models. This is real evidence. Therefore, I 20 think it's very important, particularly, in fact. 21 MR. CRAIG: How many in the last ten years'. 22 CHAIRMAN WALLIS: None in the last ten years. 23 MR. JERRY JOHNSON: No large_ seal failures have 24 occurred in the last ten years. 25 CHAIRMAN WALLIS: That's a useful statement. ~ g j' ANN RILEY & ASSOCIATES, LTD. V
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12 1 Thank you.
' () 2 MR. JERRY JACKSON: Also, as a matter of 3 background, we need to cover the BWR considerations. The 4 recirculating pumps are not considered part of the scope of 5 this issue, going back a number of years, and that was based 6 on experience and analysis that showed that the leak rates 7 were quite a bit smaller for BWRs, being it --
8 CHAIRMAN WALLIS: That's another vague statement. 9 I mean, 500 gpm is big. What's small? 10 MR. JERRY JACKSON: The BWRs' maximum theoretical 11 leak rate is around 100 gpm. The leak rate, maximum leak 4 12 rate for a Westinghouse reactor coolant pump is 480 gallons 13 per minute. 14 There's more than one type of reactor coolant
) 15 pump, and we'll go into that later, which have other 16 numbers, as well, but those are two that you can use for 17 comparison.
18 They are also at a lower pressure, as well, so 19 that affects the leak rate, as well. In the BWRs, really, 20 the main saving grace is the fact that they have reactor 21 core isolation cooling and high pressure steam and the high 22 pressure -injection feedwater systems that have a lot raore - 1 23 - that are a lot more robust in their makeup capability than ' 24 the PWRs. i 25- And the RCIC is steam-driven, so, therefore, it's l l ANN RILEY & ASSOCIATES, LTD. O' Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 m
L 13 1- available during station blackout. And station blackout is () 2 - one of the. main concerns over the years for this issue. 3 It's.been one of our main focuses. 4~ In addition to that, the recirculating loops of 5 the BWR have isolation valves that, under certain 6- circumstances, can be used to isolate the recirculation 7 pump. 8 Now, there are a couple of -- there were initially 9 a'few outliers to that, and that was the condenser isolation 10 BWRs, but.there's only two of those that are still in 11 operation today and they have done some tests on their BWRs 12 to prove that even with a loss of cooling, they can use a 13 method of thermal siphon cooling from their heat exchanger,
- L4 from their thermal barrier type heat exchanger to cool it.by 15 natural convection, and they've passed that test-and that 16 'has been submitted'to the staff and reviewed.
17 So, therefore, we have concluded that the BWRs are 18 really not -- should not be part of the scope. 19 CHAIRMAN WALLIS: Now, these pumps they've tested
.20 under SBO, they are the pumps that supply the seals?
21 MR. JERRY JACKSON: No. They are the actual
- 22. recirculating pumps.
23 CHAIRMAN WALLIS: I don't understand how testing a 24 : pump.was a' test.of seal failure likelihood. Seal failure, 25 you hope, won't occur when you test the. pump, but it might ANN RILEY & ASSOCIATES, LTD.
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14 l' occur on some kind of statistical frequency. () 2 3 MR. JERRY JACKSON: The test was to show that with a loss of component cooling water to the thermal barrier, 4 that you could still maintain cooling to the seals by a 5 thermal siphon. 6 CHAIRMAN WALLIS: So it tested the pumps under 7 conditions that challenged the seals. 8 MR. JERRY JACKSON: Right, exactly. 9 CHAIRMAN WALLIS: That means that because you've 10 tested a pump a couple of times, the seals are never going 11 to fail? I'm not sure how you do a proper test of 12 probability of seal failure without doing a great many 13 tests. 14 MR. JERRY JACKSON: Well, that's the evidence that /) ( / 15-l we have. If you go back a ways, there was an information 1 16 notice earlier on BWRs that had been sent to the industry I 17 saying that they were excluded from part of the scope of 18 Generic Issue 23 -- I believe that's correct -- but it 19 pointed out that the older isolation condenser plants would 20 have to be looked at in more detail, 21 I was cnly pointing to that fact, that only two of 22 those remain in operation and those two have had at least a 23 single test of the seal under SBO conditions. l 24 Since I was asked to give some of the background, 25 maybe we should go through a little bit of the type of i f ANN RILEY & ASSOCIATES, LTD. Court Reporters ; 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
15 1 primary and secondary seal designs that are out there now. () 2 In the primary seal area, there's two basic types; 3 the hydrostatic seal and the hydrodynamic seal. The 4 hydrostatic seal is sometimes referred to as the film riding 5 seal. That's because of the large separation and the fact 6 that the face plates ride on the film of fluid between the 7 s e2.l s . 8 The hydrodynamic seals that are shown there at the 9 bottom of the page are referred to sometimes as rubbing face 10 or nechanical seals, as their clearance is much less than 11 actually thought of as being in contact with just a 12 lubri cating film of fluid between them. 13 The hydrostatic seals have -- this is only used in 14 the Westinghouse first stage seal, and we'll go into that in O ( ,/ 15 a little bit more detail later when I put up some pictures. 16 But that seal has a non-rotating seal ring and runner that 17 are made of some ceramic material. Early on, they were made i 18 of aluminum oxide. I believe now that it's silicon carbide 19 -- 20 DR. POWERS: That really is silicon carbide, and 21 not silicone carbide. 22 MR. JERRY JACKSON: Yes, silicon carbide, right. 23 Thrc's an error. 24 DR. POWERS: I think it's a problem, because you 25 can make a silicone carbide, but it's -- f'~D ANN RILEY & ASSOCIATES, LTD. (l Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 I Washington, D.C. 20036 (202) 842-0034 l
s 16 1 MR. JERRY JACKSON: I think it's silicon carbide. [q; ) 2 CHAIRMAN WALLIS: It's silicon carbide. 3 DR. POWERS: There's no organic in it. 4 MR. JERRY JACKSON: And they're clamped to 5 stainless steel holders. And this, like I said, is only for 6 the first stage Westinghouse designs and it rides on a film 7 of coolant and the face plate separation does not depend on 8 the pump rotation. It comes from a pressure balance of the 9 face plates, the moveable face plates, but there are no 10 springs involved there. 11 It comes strictly from hydraulic forces. To start 12 up the seal, you have to pressurize it and have a small 13 amount of leakage passing through the face plate of the 14 seal. You have to have 200 pounds pressure and two-tenths
/~N ! ,) 15 of a gallon per minute is a minimal requirement.
16 So where the normal leakage through -- it's a high 17 leak rate type of seal. The normal leak rate through the 18 first stage seal is three gallons per minute. The face 19 plates clearance is considered large for seals, it's like a 20 half a 1000th. 21 The hydrodynamic seals are a little bit different 22 in that their non-rotating seal ring is usually carbon 23 graphite type of face plate that would -- it goes against a 24 runner that's some metallic hard-faced kind of material or 25 metallic carbide.
/ \ ANN RILEY & ASSOCIATES, LTD.
(_ / Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
17 l 1 CHAIRMAN WALLIS: Is the wear of these shields l (/ )k 2 understood? 3 MR. JERRY JACKSON: Understood? 4 CHAIRMAN WALLIS: Well, do they know how much wear
- 5. occurs after one year of operation, two years, five years?
6 MR. JERRY JACKSON: The wear is pretty 7 imperceptible, I think. They're really lubricated by a film 8 there. You can have wear marks, but for the hydrodynamic l 9 seal, for -- they don't touch in the Westinghouse first i 10 stage. So you really shouldn't have wear occurring, that ! 11 they're intended to be separated. They're not designed to 12 ever touch. 13 In the hydrodynamic seal, these are actually so j 14 smooth, they're lapped and measured optically. I 15. CHAIRMAN WALLIS: You mean there's never any junk j 16 in the primary coolant? . 1 17 MR. JERRY JACKSON: That has been a problem over ! 1 18 the years. That's one of the -- when we're having a lot of 19 normal operation failures, actually could build up on the j 20 seals, had become a problem. But I think the number of 21 normal operation failures.and problems associated with that ) 22 have virtually disappeared. 23 CHAIRMAN WALLIS: I'm just wondering if your 24 conclusion is based on knowledge or hope. 25 MR. JERRY JACKSON: I haven't seen any indication O ANN R1 LEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
18 1 of'-- 1 2' CHAIRMAN WALLIS: There hasn't been a failure due 3 to wear. 4 MR. JERRY JACKSON: Sir?- 5 CHAIRMAN WALLIS: There has not been a failure due
~
6- to wear. So you assume wear is not important. 7 MR. JERRY JACKSON: Right. That's always been the 8 assumption. I don't think wear is a problem. 9 CHAIRMAN WALLIS: Do you take these apart and 10 exaniine the seals periodically? 11 MR. JERRY JACKSON: Yes. In my experience, I 12 believe that they are periodically changed, although it's 13 very plant-dependent on how they operate the seals. 14 There's a lot of knowledge that's specific to that () 15 plant and sometimes the seals may go for several outages 16 without being changed, is my understanding, although they're 17 probably inspected. 18 CHAIRMAN WALLIS: So they monitor the leakage and 19 then they change them when they leak beyond a certain point 20 or something? 21 MR. JERRY JACKSON: There's a periodic inspection,
-22 when they go into a refueling outage. I'm sure that they do 23 inspect their seals. I don't know if every plant inspects 24 every seal at every refueling outage. But if there is not a 25 leak problem or no problem with the operation of the seal, ANN RILEY.& ASSOCIATES, LTD.
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19 1 then you aon't inspect it. You don't have to shut down to i A 2 do that. 3 CHAIRMAN WALLIS: Would the on-site inspectors 4 know more about what they actually do with seals? 5 MR. JERRY JACKSON: Probably. 6 MR. CRAIG: The leakage rate for the seals is i 7 routinely monitored during plant operation. Co there is an 8 indication of a degrading seal, and the operators would pick 9 it up. So it's not as if they go and find it on inspection 10' and I believe that there's a number of run hours and based 11 upon that, Westinghouse has a recommendation for seal 12 replacement. 13- MR. JERRY JACKSON: There are alarm limits on the 14 seal output from the leak-off lines and other limits that 15 are alarmed. 16 DR. SCHROCK: How is the leak rate measured? The : 17 leakage is partially steam, at least. Is that not the case? i 18 MR. JERRY JACKSON: This is during normal 19 . operation, when they're cool. So it's the leak-off line 20 leakage. There are a number of stages, we'll go into that a 21 little bit later, but -- so that you can look at leakage 22 behind each stage and you can tell -- you monitor that 23 amount. It's not steam. 24 DR. SCHROCK: I'm looking at something on a page , 25 marked B-11, where there is a temperature entropy diagram i ANN RILEY & ASSOCIATES, LTD. O- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
20 1 with a conjectural path of the -- j
) 2 MR. JERRY JACKSON:- That's a backup slide for when 3 I talk later'about loss of cooling events. Right. Station 4 blackout, loss of component cooling water, service water, 5 will result in non-cooling of the seal and then that's the 6 technical issue that we're trying to address now.
7 Our main technical issue is what happens then. 8 The seals are designed to be cooled always. 9 CHAIRMAN WALLIS: I'm sorry to interrupt. Do you 10 have an estimate of your timing? You've got 25 of some of 11 the densest slides'I've ever seen as part of these 12 presentations and I think it's going to be very interesting, 13 but you may take all morning if we're not careful. 14 MR. JERRY JACKSON: Paul had asked me to go O ( s/ -15 through some of the background. I may have overdone it. 16 I'm glad to go-forward at any rate that you'd like to, 17 that's quite all right with me. 18 CHAIRMAN WALLIS: I just wondered if you had done 19 a dry run or something and got an idea how long this was 20 going to take. 21 MR. JERRY JACKSON: I'll try to go faster. 12 2 CHAIRMAN WALLIS: I think what I would personally 23 be interested in would be what are the key technical issues, 24- and not a lot of history, unless it's relevant, unless it 25 really tells us what we need to know. What are the key ANN.RILEY & ASSOCIATES, LTD.
~' Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
21 1- problems? What are_the key things that we might worry () 2 3 about? MR. JERRY JACKSON: Of course, my lead-off slide 4 was telling that the main concern is loss of cooling event. 5 We're no longer concerned with the normal operation 6 failures. And the technical issue behind the loss of 7 cooling is will the seal fail in any way. 8 Through our experience over the years, our 9 research and testing, we've determined, for instance, in the 10 Westinghouse seal, which was our real concern initially, was 11 for the Westinghouse seal only, because it's a different 12 type of seal. 13- The first stage seal takes the full pressure drop 14 across the seal, all but 50 pounds of that 2250 to 50 across
) 15 the first stage seal, and so we were concerned about that.
16 And we tested the 0-rings ~, because it was thought initially 17 .that the O-rings were the weakness in the seals. The soft 18 materials, would they fail under loss of cooling. 19 CHAIRMAN WALLIS: Why is loss of cooling a problem 20 for a seal? 21 MR. JERRY JACKSON: Because you have -- well, 22 that's what I'm getting to. There are two kinds. The O-23 rings, you have soft materials that can fail at high 24 temperatures. You have O-rings, U-cups that are in the 25 Westinghouse seal that are Teflon. You have O-rings -- you O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
= 22 1 have U-cups in the hydrodynamic seals, and all of these are () 2 3 soft materials that could fail at the higher temperature and extrude out the gap or actually just come apart in some of 4- our tests that have occurred. 5 .We actually -- 6 CHAIRMAN WALLIS: Loss of coolant accident, 7- usually the temperature goes down. It may go up for a very 8 brief moment,-but usually it goes down. 9 MR. JERRY JACKSON: The seals are normally cooled 10 to about -- 11 CHAIRMAN WALLIS: I misunderstood. I thought the 12 problem was the seal itself creating a loss of coolant 13 accident. 14- MR. JERRY JACKSON: That's correct. () 15 CHAIRMAN WALLIS: I thought you meant, in your 16 context, that there had been a LOCA and then the seal 17' failed. 18 MR. JERRY JACKSON: No. It's a loss of cooling to 19 the seal. The seals are normally cooled. They're never -- 20 21 CHAIRMAN WALLIS: We've got to say what loss of 22 cooling we're talking about. Loss of cooling doesn't mean
;23 LOCA. It means loss of cooling of seal.
24! MR. JERRY JACKSON: Yes. I think my first slide 25 said loss of off-seal cooling. ANN RILEY & ASSOCIATES, LTD.
\_- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034-
23 1 DR. POWERS: When you talk about these soft f%. ( ) 2 materials, what kind of radiation dose rate could they get 3 normally, during normal operations? 4 MR. JERRY JACKSON: I'm not sure I could answer 5 that 6 DR. POWERS: Round number? Materials do have a 7 mechanism under dose rate. 8 MR. JERRY JACKSON: That was considered in our 9 test that we did at AECL in Canada and when we tested the 10 Westinghouse 0-rings, because initially, Westinghouse, when 11 they came in to us, indichted this is the only failure 12 mechanism that could occur. 13 They tested their 0-rings full-scale in Pittsburgh 14 at one of their -- where they manufactured a seal and they ( t (_j 15 had some problems with them that they thought was a result 16 of their test facility. 17 So that led us to a test program of our own at 18 AECL and we joined in with the Westinghouse Owners Group, as 19 well, into this test later on and we determined that under 20 the conditions that would result when you lose off-seal 21 cooling, the gaps, the temperatures, the pressures, that 22 each individual stage would see, that the 0-rings that they 23 were using at that time would extrude, would fail, and that 24 the channel seal would fail, but that the 0-ring behind it 25 would still hold. h k-ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
24 1 So that's where we -- that is the test that we did 2 on the Westinghouse seal. 3 Subsequent to that, Westinghouse identified new 4 material for their 0-rings and they tested them under the 5 same. kind of procedure, same conditions, proved that under 6 these loss of cooling events, that they would survive. I 7 Those are called -- have been referred to in our report as a 8 newer material. So they're qualified for this temperature. l 9 DR. POWERS: If you go to the chemical handbook to 10 look up polymeric materials, looking under newer material 11 won't help you very much, will it? 12 MR. JERRY JACKSON: Right. This is a -- in my 13 understanding, that Westinghouse supplies these 0-rings 14 based on a batch testing. They procure a batch of this 15 material, have 0-rings made, and they test samples of these 16 in the same type of procedure that I just talked about to 17 show that they would succeed, and then these -- 18 CHAIRMAN WALLIS: Do they test them under the 19 worst conditions they can think of, without them being 20 cooled? Is that the idea? 21 MR. JERRY JACKSON: Right. 22 CHAIRMAN WALLIS: And then they see how long it 23 takes before they fail. l j 24 . MR. JERRY JACKSON: Well, not the worst conditions 25 that they can think of, but the conditions that they would l ANN RILEY & ASSOCIATES, LTD. .O Court Reporters ' i 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
25 1 expect in an event, a loss of cooling event to the reactor
'2 coolant pump seal. Then these O-rings are the ones that 3 'they supply as their new material, improved material, that
-4 are qualified for-those conditions.
5 DR. POWERS: They surely must be going to tell you 6 what it!is. 7 CHAIRMAN WALLIS: We don't know what the material 8 is? You don't know? It's a secret? 9 MR. JERRY JACKSON: I don't think it's a s ret. 10 I think I could probably find out the basic type of material 11 from Westinghouse. 12 CHAIRMAN WALLIS: So what we have is their 13 assurance that they have a new material which passes their 14 test. Is that what we have, the assurance from Westinghouse 15 that there is a new material that passes their test? 16 MR. CRAIG: I think that the situation with
- 17. respect to the materials, in the early days, with 18 Westinghouse seals, with the initial design for the polymer 19 in the seal, there were a number of failures during normal 20 plant operations.
21 As a result of that the staff identified that 22 this was a source for a small break LOCA. This issue got j i
-23 identified. But we did not see failures from other pump
- 24. vendors. Their seal designs have different materials, 25 they're more robust. So we began'to look at Westinghouse.
'O V
ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 L l
l 26 1 Westinghouse saw this as an issue that needed to () 2 3 be addressed and conducted extensive testing and developed a new seal material, and that seal material has been and 4 continues to be installed in pumps and it's been tested. 5 They have tested it for the radiation at the 6 levels that the pumps are going to see and, Dr. Powers, I l 7 don't know precisely what that is, although I'm sure if I 8 asked Westinghouse, they'd tell me, i 9 We have a general idea, I think, in meetings with 10 them, they've talked about the seal material and the design. 11 It is proprietary and we haven't gone into great detail to 12 do an analysis of the material itself. 13 What we have seen is a significant reduction -- 14 i.e., no failures in an extended period of time -- of () 15 Westinghouse pumps with these new seals. 16 As a result of looking at this issue, the staff 17 then identified that since the seals were, if you will, a ' 18 potential source of failure, what could cause the seals to i 19 fail, and from that we got into discussions of station i 20 blackout and coping analyses, and we'll talk about that in a 21 couple of minutes. 22 Then if you don't have a station blackout, what 23 are the causes for loss of cooling to the seals themselves, 24 and.that was sort of the thrust and the overview of the 25 presentation that we intended to give. But it's not a ANN RILEY & ASSOCIATES, LTD. A_/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
f~ I 27
- 1. matter that the staff doesn't understand precisely what the 2
) materials are. Westinghouse won't give us the material. It 3 is proprietary, the seal design is proprietary. But we have 4 not gone into the level of detail.
5 MR. JERRY JACKSON: I think the main technical 6 reason that we have confidence in it is that the material 7 that they were using earlier did fail under our own test and 8 they acknowledged that and they used the same type of test 9 in the material that they have identified, and we thought 10 -this was a -- we had confidence in these tests to show 11 whether the seal -- whether the material would fail or not. 12 CHAIRMAN WALLIS: Your resolution of this issue is 13 based on risk analysis, I understand. 14 MR. JERRY JACKSON: Right. (Aj 15 CHAIRMAN WALLIS: So the output from any analysis 16 of the physics.has to be some probabilistic information. 17 DR. POWERS: And that's the problem we're running 18 into, is that I don't know what the material is, I don't 19 know which radiation sensitivity. 20 So you observe zero failure. How do you go about 21 ~ constructing a probability to stick into the event tree? 22 Yes, I could use a standard Bayesian update for zero failure 23 cases and I'd probably get away with that, but I'm going to 24 feel guilty. I mean, my soul is going to be offended. 25 MR. JERRY JACKSON: We haven't covered all the I I [~) ANN RILEY & ASSOCIATES, LTD.
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28 { 1 failure mechanisms. Actually, the soft materials are ' '( 2 probably the easiest ones. If we think of -- we identified 3 the Westinghouse 0-rings as a. problem, the old material. If 4 we assume that the new material is qualified, then we -- in 5 a loss of cooling event, we don't assume that the 0-rings 6 fail in our probabilistic model. 7 But'the main -- 8 DR. POWERS: That ought to make you feel even 9 worse than I do when I do my Bayesian update on zero 10 failures. I mean, to say that this stuff will not fail, 11 zero probability in the event tree. This is amazing 12 material. There is no probability that t.his will fail. 13 DR. KRESS: I think they assume a probability of 14 one if you lose cooling. () 15 MR. JERRY JACKSON: If you lose cooling, with the 16 outer material, after two hours, but that's not even the -- 17 the main mechanism for failure is the popping open of the 18 seal. So the.O-ring,-the soft material, was the one that we 19 have the most confidence in that we've tested. 1 20 CHAIRMAN WALLIS: Are there any of these old O- I
- 21. rings from old materials out there or is it all new 22 mat larial?
23 MR. JERRY JACKSON: It's being changed out. Some 24 of the plants, in our understanding, still are using the old ; 25 material. In our recent meeting with the ownere group, we ANN RILEY & ASSOCIATES, LTD. s/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202). 842-0034
i 29 , 1 asked them to supply that information of what plants had () 2 3 changed out their material. CHAIRMJ.'T WALLIS : So you're proposing to say this j i 4 is no longer an issue because of new materials? i 5 MR. JERRY JACKSON: No. 6 CHAIRMAN WALLIS: You don't know if it's in there 7 yet? 8 MR. JERRY JACKSON: When we get to the ! l 9 probabilistic analysis, we'll cover our assumptions that 10 were made and the use of the model and then the risks that l I 11 result from each plant when that's covered. l l 12 CHAIRMAN WALLIS: Part of the argument was that l 13 they fixed the problem with the seals by putting in better j 14 seals. () 15 MR. JERRY JACKSON: That's only for the 0-ring i 16 material. There's still the problem of popping open, the - 17 hydraulic instability that I haven't covered yet. That's 18 really the main failure mechanism. 19 CHAIRMAN WALLIS: Maybe we should get to that. 20 MR. JERRY JACKSON: Okay. Should I go back to the 21 seal description or where would you like for me to -- 22 CHAIRMAN WALLIS: Well, we need to know enough to i 23 understand what you mean by popping open. Maybe you need to 24 -- maybe some figures would be good; actually, pictures. 25 MR. JERRY JACKSON: Okay. 1 ANN RILEY & ASSOCIATES, LTD. O' Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 i Washington, D.C. 20036 (202) 842-0034
30 1 CHAIRMAN RALLIS: Not too much detail, n 2 MR. JERRY JACKSON: This is just a picture cf the 3 reactor coolant pump. Then the seal is located in this area 4 here. 5 CHAIRMAN WALLIS: So the seal is as big as the 6 pump. Well, the seal pod looks as big as -- it's a pretty 7 significant part of the whole. 8 MR. JERRY JACKSON: This is the seal that's in the 9 -- you're looking.at a Westinghouse pump. This is the 10 motor, this is the actual pump itself, and the outlet of the 11 seal is here. This is the seal package that goes around the i 12 a nine-inch sh'ft here. It's a three-stage seal. 13 This is just an overview of the seal package i 14 itself. I think this slide will explain a little bit more () 15 the operation at least of the Westinghouse seal. There's 16 two different types, so we'll have to talk about those 17 later. , 18 But the' Westinghouse seal, this is the shaft, the 19 nine-inch shaft,. this is the first stage. These are the two 20 ceramic face plates in the first stage. 21 You have injection cooling coming in here. 22 CHAIRMAN WALLIS: 'It squirts through between them? 23 MR. JERRY JACKSON: Right. The injection cooling 24 comes from the charging pumps or high pressure injection and 25 this cooled water comes in at 50 pounds above reactor
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ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
31 1 pressure. So that flow goes down the shaft into the pump () 2 3 bowl, blocking the hot reactor coolant from coming up through there. 4 So you have a pressure drop across the first stage 5 from 2250 to the exit of the seal faces near the OD of the 6 pump shaft; that's 50 pounds pressure. Then it flows up 7 through'this a.ea to the second -- 8 CHAIRMAN WALLIS: So we have 2200 psi on those 9 ceramic plates. If a plate fails, we get 2200 psi all the 10 way up to the next seal. 11 MR. JERRY JACKSON: Right, exactly. That's right. 12 And this seal is balanced by pressure on the back side. Let 13 me show you a schematic. I'll come back to this in a 14 minute. () 15 I think-this is reversed, but if you -- reversed 16 ~ in direction, but if you have the high pressure flow through 17 here to the low pressure flow, you have high pressure across 18 this area of the seal ring here chat's pushing down on this l l 19 area. The pressure that's trying to push it up, it goes l 20 from 2250 here to 50. 21 So'if you integrate these pressures, they balance 22 so that you have a three gallon per minute flow of cooled 23 water through there. There are no springs involved. So the ! 24 problem for popping open, simply, without going into too 25' much detail, is the fact that when you lose cooling and the i f. \- ANN RILEY & ASSOCIATES, LTD. Court Reporters , 1025 Connecticut Avenue, NW, Suite 1014 ' Washington, D.C. 20036 (202) 842-0034 ;
32 ' 1 hot reactor flow then comes through the -- comes up from the [} 2 bowl-of the pump along the chaft and begins to pass through 3 the seal, you can have flashing occurring between the seal l 4 faces. 5 That changes this pressure distribution 6 drastically and this is called a balance. These are all 7 balanced seals. Balanced means that the hydraulic pressure 8 forces that are on the top of the seal here are large enough 9 to keep it closed positively. So when you have flashing _ 10 occurring, then the seal can go all the way to the stop up 11 here. It basically comes open. Remember, it's a half a 12 1000th separation. l 13 Now, it,can move up three-quarters of an inch, so 14 it basically disappears. That's the concern of popping () 15 open. 16 CHAIRMAN WALLIS: So the previous figure you 17 showed us was of a different kind of seal or symbolic? It 18 doesn't look like the second one. 19 MR. JERRY JACKSON: This is just a symbolic 20 picture of the seal. 21 CHAIRMAN WALLIS: The figure before that. 22 MR. JERRY JACKSON: I'll go back to that. 23 CHAIRMAN WALLIS: It didn't look this figure. The 24 detail doesn't look like that. 25 MR. JERRY JACKSON: It's reversed. That's part of l O ss ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 i Washington, D.C. 20036 (202) 842-0034
, 33 1~ the problem. I apologize for that.
2 CHAIRMAN WALLIS: There's no runner and there 3 seems to be two seals there instead of one. 4 MR. JERRY JACKSON: No , this is the whole assembly 5 here. I can show you.
'6 CHAIRMAN WALLIS: That's all right. It's just my 7 misunderstanding maybe..
8 MR. JERRY JACKSON: If you look at the individual 9 parts, it might be a little clearer here. Here are the two 10 face plates. They're clamped with stainless steel ring 11 holders here. Here is the critical 0-ring, the secondary 12 seal, and this area up here is where the full pressure acts 13 down on the seal. Here is where 2250 comes in, exits at 50 14 pounds pressure when it's cooled, and this force is what -- v) 15 16 CHAIRMAN WALLIS: I don't see any runner in there. 17 MR. JERRY JACKSON: This seal is attached to the 18 shaft. 19 CHAIRMAN WALLIS: That's the one with the runner, 20 the bottom one. I 21 MR. JERRY JACKSON: .Right. Right. This one 22 actually floats. It's stationary. This 0-ring and channel 23 seal here take out the axial motion that occurs in this
-24 direction.
25 CHAIRMAN WALLIS: So not only is it reversed, it's O. ANN RILEY & ASSOCIATES, LTD.
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)
l 34 1 upside down. , 2 MR. JERRY JACKSON: I think it's the same. l [\--) l 3 CHAIRMAN WALLIS: Upside down, because the runner 4 is on the bottom. 5 The runner is on the bottom. It must be on the 6 following slide. There is no runner in the top seal there. 7 MR. JERRY JACKSON: No. 8 CHAIRMAN WALLIS: But there is on the bottom seal? 9 MR. JERRY JACKSON: Yes. The bottom seal I 10 believe is the one that's attached to the shaft. So it 11 rotates with the shaft. This one is stationary at the top. 12 CHAIRMAN WALLIS: That's not consistent with the 13 other detail, either. The only reason I'm asking is to see ) 14 if you guys understand what tne issue is, that's all. l () 15 MR. JERRY JACKSON: I don't know if that's a i 16 misnomer on the nomenclature, but on both of those drawings, 17 I believe the bottom portion is the part that's attached to 18 the shaft and rotates with the shaft. The top part is 19 stationary in that it's not rotating with the shaft and it's 20 free to move in an axial direction. 21 DR. SCHROCK: Is this on the hydrostatic seal? 22 MR. JERRY JACKSON: Yes. This is the hydrostatic 23 seal. This is the Westinghouse first stage hydrostatic seal 24 and it's the one that we had the most concern, especially 25 initially, for popping open. t-i
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35 1 DR. SCHROCK: What is it that fixes that half-() 2 3 1000th clearance?' MR. JERRY JACKSON: It's balanced by the hydraulic 4 forces. You have a small radial angle, an approach angle 5 that's coming in here. It's 200 micro-radiants and the flow 6 'that goes through it, when it's balanced, when the seal is 7 cooled under normal pressure, three gallons per minute 8 faster _than number one seal face plates. 9 The gap is se';. This can vary from startup, two-10 tenths of a gallon that I showed initially that you needed 11 to start up, would have a smaller separation. You would 12 have a larger separation as it opened up and leaked more. 13 The alarm rate during normal operation is at five 14 gallone. per minute. () 15 DR. SCHROCK: So it-somehow seeks a clearance , i 16 during operation. 17 MR. JERRY JACKSON: Right, exactly. 18 DR. SCHROCK: How do you know what that is? I saw 19 a number in here to two significant figures. So you must 20 have a way of -- 21 MR. JERRY JACKSON: That's the nominal clearance 22 for three gallons per minute that was quoted by Westinghouse 23 for -- 24 DR. SCHROCK: Calculated from the flow rate, 25 maybe? I~N ANN RILEY & ASSOCIATES, LTD. \~- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
l 36 1 MR. JERRY JACKSON: I don't think they -- possibly ( 2 .that's where.it comes from. That's not an important number 3 in the clearance, because it is variable as the flow 4 changes. The important thing is that the balance is 5- maintained. 6 If you look at a schematic of a hydrodynamic type 7 of seal, the main important feature is that it has a spring
- 8. in addition to the hydraulic forces that are acting on it to 9 keep it closed. So you have that force, as well.
10 CHAIRMAN WALLIS: What's this thing that's holding 11 the spring? It's beside the shaft, that long thing that 12 ends -- it doesn't end. It's cut away at the top. What is 13 that long thing that holds this? There is a shaft and then 14 there is something else. What's that long -- what's the
) 15 . next thing? Where does that go?
16- MR. JERRY JACKSON: I don't know. This is just a 17 schematic drawing. I don't know what that's intended to 16 show. It may be the way that this rotating face is attached 19 to the seal. It doesn't show clearly in that view. It's 20 only intended to be a schematic.
'21 DR. SCHROCK: Why would a schematic show a 22 separation between the shaft and parts that are supposedly 23 attached to it and rotating with it?
24 MR. JERRY JACKSON: I'm not sure. 25 CHAIRMAN WALLIS: Excuse me. I have an ANN RILEY & ASSOCIATES, LTD. s/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
37 1 appointment which I cannot avoid, I'm afraid, and I will be () 2 3 right back as soon as I can. my colleague, Dr. Kress. I'm going to pass the gavel to Maybe my colleagues can find out 4 enough about the details, they can explain it to me during 5 the break. 6 DR. KRESS: Is that a challenge? 7 CHAIRMAN WALLIS: Yes. 8 DR. KRESS: Don't worry about him. Just keep 9 ' moving. 10 MR. JERRY JACKSON: Should we continue with some 11 of the pictures or I go back?
.12 DR. KRESS: I don't know. Do you think you 13 understand?
14 DR. SCHROCK: I'm afraid I'm still a little fuzzy () 15 about the overall intent here. It sounds to me as though 16 the problem is that the things sometimes have failed and 17 when they do, the consequence of that is a small break LOCA, 18 with a leakage path via the clearances in the pump. 19 Now you're showing us a lot of detail about the 20 seal, two different types of seals, and talking about the 21 . normal operation of those things. The mechanism of the 22 failures that are important hasn't come out clearly, to me ; l 23 at least. l 24 MR. JERRY JACKSON: The two mechanisms of failure l 25 that have been identified are the failure when all seal 1 [~'% ANN RILEY & ASSOCIATES, LTD. Ts /- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 i (202) 842-0034 ) i I
38 1 cooling is lost and the temperature rises inside the seal package of the 0-rings, soft materials, 0-rings, U-cups, (a~ ) 2 3 channel seals, that could all fail. They are non-metallic 4 components. They are not intended to operate at those 5 temperatures. 6 The other failure mechanism that has been 7 identified is what's been referred to as popping open or 8 hydraulic instability. It's when you lose those closing 9 forces that we've talked -- when they become unbalanced due 10 to flashing occurring between the seal faces. 11 When seal cooling is lost and you have 550 degree 12 water at 2200 pounds coming in instead of 2250 pounds of 13 water at nominally 100 degrees during normal -- 14 DR. SCHROCK: So does the pump seize when that Q' 15 occurs? 16 MR. JERRY JACKSON: No. 17 DR. SCHROCK: It~ continues to rotate. 18 MR. JERRY JACKSON: No. Most events that occur 19 under loss of off-seal cooling are like station blackout, 20 when there is not power to the pump. So it's not rotating. 21 Or if you lose component cooling water or service water, if 22 you lose ~ cooling to the seal, they would not be operating 23 the seal in an uncooled condition, because all the seals -- 24 all the seal packages are intended to be cooled when 25 they're operating. (h.
\, /
ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
39 1 DR. KRESS: Is there a thermocouple on the seal or pump?
) 2 3 MR. JERRY JACKSON: Yes, there's thermocouples and i 4 measuring the outlet, the number one leak offline, the 5 various flows that come from the seal.
6 DR. KRESS: And that causes the pump to turn 7 itself off. 8 MR. JERRY JACKSON: No. I think this is part of 9 the plant operating procedures. You just wouldn't --
' 10 - DR. KRESS: You look at that temperature and the 11 operator will turn the pump off.
12 MR. JERRY JACKSON: Right. And flow. It's 13 alarmed at five gallons per minute, for instance, and by 14 Westinghouse's analysis and analysis that we have checked, () 15 when you lose cooling to the seal, the first stage seal will 16 begin to open up, as we talked about, and the flow will 17 change from three gallons per minute to around 23 09'.lons i 18 per minute flow through there. 19 That's above the alarm limit, for instance. Now, 20 that's still relatively close, that 21 gallons per minute. 21 The concern or the technical issue that we have is does 22 flashing occur between the seal faces and to a sufficient 23 degree that they actually pop open. And it's not 21 gallons i 1
-24 per minute, but it can get into much larger leak rates.
25 That's what the seal model is predicated on, and T. ANN RILEY & ASSOCIATES, LTD. [/ \_ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
40
- 1. maybe we should talk just a little bit about that.
() 2 I don't know if this will help or not. If you 3 look at an event tree, this represents the modeling of the 4 Westinghouse seal, where you have three stages. The upper j 5 paths are the success paths. The lower ones are the failure 6 paths. When all seal cooling is lost, but you have no 0- ) 7 ring failures, you have'no-popping open to occur in any of 8 the seals, then 21 gallons per minute is the expected leak 9 rate. We're talking about a Westinghouse seal. I 10 Then you have various paths for failures that 11 could occur for -- the popping open is referred to as l 12 binding here. That's because, also, if the O-rings are 13 extruded, they can pull the seal faces open. So those two i 14 failure modes are actually combined and then you see the () 15 otl.er ones are for the second and third stage 0-ring 16- ; failures, et cetera. 17 So you end up with a variety of paths that leak j l 18 and Art Buslik will address this a little bit later when he l 19 goes into the probabilistic analysis. But this is the type 20 of modeling that was done. This was done initially by 21 Westinghouse in their W-CAP-10541. They modeled their seal 22 under station blackout conditions and this is the seal model i 23 they have. 24' Now, of course, there are probabilities assigned 25 .to these paths. There is some disagreement with i l ANN RILEY & ASSOCIATES, LTD. ! (_/ Court Reporters i 1025 Connecticut Avenue, NW, Suite 1014 i Washington, D.C. 20036 { (202) 842-0034 i m . . . . . .. . . ..
41 1 Westinghouse on what those different probabilities are and () 2
~
most of the failure probabilities are fairly low. ; 3 The' highest probability is for success, it's like 4 more than 80 percent or so success to 21 gallons per minute. 5 DR. SCHROCK: And the fluid that's leaking is the 1 6 -- 7 MR. JERRY JACKSON: Is reactor fluid. 8 DR. SCHROCK: -- reactor primary coolant, which is 9 at operating _ temperature. 10 MR. JERRY JACKSON: Right. 11 DR. KRESS: When I see numbers like 21 and 183, I 12 presume that was calculated by some flow model of pressure. 13 MR. JERRY JACKSON: Right. Westinghouse did a 14 complete -- W-CAP-541 is a rather large document and they () 15 did it very detailed. It took them quite a long time to do 16 this. They did a detailed thermal-hydraulic analysis, l 17 stress analysis, so you know what the gaps are between-18 there, you know what all the pressures, temperature 19 distributions.
- 20 DR. KRESS: Loss of coefficients.
21 MR. JERRY JACKSON: And we had ETEC, out in j 22 -California, to do, as a contractor for us, to -- we arranged 23 with Westinghouse, after some period of negotiation, to get 24 the actual drawings, et cetera, for the pump, and they went !
- 25 through the same kind of analysis to verify what was done l
~[ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 ! Washington, D.C. 20036 l (202) 842-0034 l l I
42 1 there and came up with virtually the same flow rates, I (f 2 think. 3 I can't remember all of them, but I will give you 4 one, for example. They came up with 440 gallons per minute 5 instead of 480, and I think those were fairly -- 6 DR. SCHROCK: And those were calculated 7 quantities. 8 MR. JERRY JACKSON: Those are calculated 9 quantities. 10 DR. SCHROCK: Is that the Rhodes model? 11 MR. JERRY JACKSON: The Rhodes model refers to 12 this very same model. David Rhodes is the name, as a 13 person, his name is attached to the model. We had AECL, who 14 is our primary subcontractor and seal expert in this area,
) 15 to review the Westinghouse W-CAP-10541 that this is
]
1 16 predicated on, and he reviewed this for us and the 11 7 probabilities and the explanation-of the probabilities that 18 he came up with on the various event trees are what's 19 referred to as the Rhodes model. 20 That's the main difference between what 21 Westinghouse has modeled and what we -- 22 DR. SCHROCK: Does it deal with the calculations 23 of flow through that complex geometry or does it deal with 24 some other considerations that lead to these probabilities? 25 MR. JERRY JACKSON: Well, it's based on our i I)
~/
ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 ' Washington, D.C. 20036 i (202) 842-0034 l 1
43 1 ' experience from the O-ring testing, because we have to make [\m)1. 2 assumptions of whether they have new material or the old 3 material, what the failures would be of the various -- 4 DR. SCHROCK: I'm tempted to ask for a reference 5 on Rhodes models, so I can educate myself about what it 6 does. I know about flow through tortuous small passages, 7 I've done research on that. I can advise about that aspect 8 of the thing. 9 If that's what it is, I'd like to see the Rhodes 10 model. If the Rhodes model is something else, then maybe I 11 don't want to see the Rhodes model. 12 MR. JERRY JACKSON: You have to combine three 13 things, I think, to really get a complete picture. Possibly 14 look at the W-CAP-10541, the Westinghouse document that it A ( ,) 15 came from. The Rhodes model is in -- I can't remember the 16 ' document number offhand, but I can supply it to you, that ) 17 contains the Rhodes model, and then you might want to look 18 at the ETEC analysis that verified those flow rates, too, if 19 you're interested. 20 MR. BUSLIK: It's the cost-benefit factor. 21 MR. JERRY JACKSON: Right. Do you know the number 22- offhand / 23 DR. POWERS: Before we leave this slide. In the l 24' discussion on the probabilistics, will we go into the tree a 25 little more closely? It's just not obvious that all the l ANN RILEY & ASSOCIATES, LTD. s- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i
44 ; l' questions-are independent probabilities. ! l [ Y 2 MR. JERRY JACKSON: I think Art will probably G' 3 explain how he used this and go into his assumptions in 4 applying this model to the plant-specific values that he 5 got, and that might be where your questions lie. I don't ! 6 know. 7 DR. KRESS: Particularly, when you have series 8 seals and one of them in front has a probability of not i 9 failing and the one after it has a probability of failing, 10 that surely.is not an independent -- 11 MR. JERRY JACKSON: It's not, because pressures l 12 change, distributions. You have to look at the whole 13 analysis. This is an analysis not only of the seal, but of 14 the leak-off lines, even -- and where the choking occurs. () 15 You really have to take into consideration the whole 16 package. 17 DR. KRESS: But the end product gives you a 18 probability of frequency of certain leak rate. 19 MR. JERRY JACKSON: Of a certain leak rate and 20 then you integrate that over time and that would give you 21 your probability then of core uncovery. l 22 DR. POWERS: What you get concerned about is you l 1 23 take an event and you break it down into lots and lots of l 24' sub-events and you have no idea what the probabilities are. I 25 So you put in round numbers, and you can make anything go t ANN RILEY & ASSOCIATES, LTD. Court Reporters
.1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
45 I 1 away. () 2 3 If I can break it down, any event, breaking down far enough, I can make the probability go to zero. That's 4 one thing you worry about. And the next thing you worry 5 about is that the probabilities of one affecting the 6 probabilities of the next in a way that's difficult to 7 portray in a tree like this. 8 MR. JERRY JACKSON: There have been some tests to 9 back this up, although testing of a full-scale seal is a 10 very expensive operation. The Westinghouse Owners Group, I 11 believe, entered into some agreement for testing in Europe, 12 of a European version of the Westinghouse seven-inch seal, 13 that was tested at full scale seal package, and there wasn't 14 a failure. (D (_) 15 Remember, the most likely probability is 21 16 gallons per minute. They had one spike that occurred, I 17 believe, in the second stage seal or at lEdst a spike in the 18 flow that occurred to like 64 gallons per minute, then it 19 closed back down and then the valuet were below the 21 l 20 gallons per minute. 21 So the problem is that you don't have many loss of 22 cooling events that you can model this event on. There are 23 some limited values and we -- 24 DR. POWERS: You're hitting at the heart of the 25 issue. You have very few data and breaking it down to this 1 l l l AIST RILEY & ASSOCIATES, LTD. [/ \-- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
z-- 46 1 kind of detail is simply fooling yourself. (N; 2 MR. BUSLIK: I don't think necessarily so. For 3 each path to obtain the leak rate corresponding to that 4 path, that's okay. As far as -- it's true that, for 5 example, if you say there is a 20 percent chance of the 6 second stage popping open, this'comes from a single thermal-7 hydraulic calculation, with estimates of what would happen 8 if the seal faces were warmed or whatever. 9 But then they say that the third stage pops open 10 or Rhodes says this third stage pops open with a probability 11 of one given the second stage pops open. So I dont think 12 that breaking it up in this way is so bad. 13 MR. JERRY JACKSON: There's a lot of things known 14 about, like, the third stage, for instance, is not intended () 15 to accept the full pressure. It's just really -- 16 DR. POWERS: It may be that the tree has a false 17 complexity to it, if everything after two questions is one 18 or zero, then it's no tree at all and it's fine. I mean, 19 there is no trouble with it. 20 MR. JERRY JACKSON: But you have to consider all 21 the failure paths to get the leaks, the integrated leak 22 . rate. It basically breaks down to 0-ring failures and the 23 time of the 0-ring failures then breaks down to whether 24 . seals pop open or not, and you have three stages of seals. 25 In Westinghouse, the main concern, the only place l [ ANN RILEY & ASSOCIATES, LTD.
'\- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
F-47 1 that has a high probability is the failure of a second stage () 2
.3 seal and the second stage seal is a backup seal. It normally operates with just a 50-pound pressure differential 4 across it and when you lose cooling, it changes types of 5 operation from a hydrodynamic seal to hydrostatic seal.
6 And on a loss of cooling event, when this is j 7 analyzed, but when you -- by Westinghouse and by our 8 contractors, the second stage seal has to rotate, pinch 9 closed, and not leak. But it has to leak a small amount of 4 10 fluid, enough that you maintain boiling condition behind the 11 second stage seal. 12 This is to assure that failure doesn't occur and 13 if any of those conditions don't occur or if you have enough 14 leakage through it, it can even pop open. So that's the () 15 reason there is a 20 percent probability by our experts that 16 where it's applied to the second stage seal failure. 17 The other failures are very low probability. If 18 you consider new O-rings in the Westinghouse seal, then
]
19 that's really the only weak point is the second stage seal 20- failure of 20 percent probability. 21 And, granted, we don't have a lot of data points t 22 for experiments that can answer that question.
.23 DR. KRESS: You're looking at the final product to 24 get'the time at which the core uncovers, factoring in makeup 25 water ~you have from various sources. / \ ANN RILEY & ASSOCIATES, LTD. - \.) Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 !
(202) 842-0034
48 1 MR. JERRY JACKSON: If there are any. Like ( ) 2 station blackout, there might not be. 3 MR. BUSLIK: The problem is that under the 4 conditions where you have real risk, you don't have makeup 5 water. During the station blackout, you don't. 6 DR. KRESS: Because you've lost your other 7 sources. 8 MR. BUSLIK: In the case of loss of component 9 cooling water or essential service water, the pumps that 10 require.-- that are needed for makeup may be dependent, for 11 example, for pump bearing coolant or component cooling. 12 That's where the real risk comes. 13 If you look at normal failures, normally, you will 14 have the mitigating systems available and, therefore, they 15 don't make such a good eontribution to risk. 16 DR. KRESS: That's fine. 17 MR. BAHADUR: Perhaps if the subcommittee feels 18 you have heard enough about seal failure mechanisms and the 19' details, maybe we can move to the next portion of our ! 20 presentation. 21 DR. KRESS: I was about to suggest that. Yes. 22 MR. BAHADUR: Especially in light of the plant-23 specific analysis. ; 24 DR. KRESS: Good. , l 25 MR. BOEHNERT: Do you want the slides, too? l' ) ANN RILEY & ASSOCIATES, LTD. \s / Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
L 49J
'1 MR. CUNNINGHAM: I'm going to come back and use 2 them for about two minutes and talk about -- just give you 3 an introduction and then we'll go to Artis thick 4 presentation, if you vill.
5 I'm Mark Cunningham, from the Office of Research, ; 6 in the PRA group. In a sense, we have danced around a 7 number of things this morning on why this is a significant
-8 issue,.why we're concerned about leak rates from reactor 9 coolant pump seals and things like that.
)
10 It comes back to something Jerry said early on; 11 you can lose seal cooling to the -- you can lose cooling to 12 the reactor coolant pump seals in a couple of important l 13 ways. One is station blackout accidents. The other is loss 14 of component coolant water or emergency service water. 15 They're important because, as Art said a little 16- bit ago, the loss of seal cooling here leads to some sort of 17 seal failure using that probabilistic model that was 18 ' discussed a little bit earlier'. You can get a small -- in 19 effect, a small LOCA in the system. 20 .These initiators of-that small LOCA, in some 21 designs, can also fail your high pressure injection pumps. 22-- So you're concerned that you've got a small LOCA and no
-23 capability to provide ECCS water back.
24 That's why these two issues are most prominent, if
~
.25 .you will, in all of the issues that are associated with O.. -ANN RILEY & ASSOCIATES, LTD.
V Court Reporters 1025 Connecticut Avenue, NW, Suite.1014 Washington, D.C. 20036 (202) 842-0034 ~ ._
50 6 , 1 reactor coolant pump seal performance. b) 2 When the station blackout rule was promulgated, 3 there was an assumption built into the rule on what type of 4 leakage we'd be getting through the reactor coolant pump 5 seals. There was also a condition, in a sense, put into the 6 rule that when GI-23 was closed, we needed to make sure that 7 the closure of 23 didn't somehow bring into questions the
- 8. assumptions that were set up during the rule.
9 So Art is going to talk a little bit about that 10 issue of now that we know what direction we're going on the 11 23, does it change our conclusions about the coping analyses 12 done for the station blackout rule. So that's the first 13 part of what he's going to do. 14 The second part of what Art will-talk n out is b (_j 15 this issue of component cooling water and service, emergency 16 service water induced seal failures. What he'll say 17 basically is that you can see that for a number of reasons, 18 this is a very plant-specific issue in terms of the risk 19 implications of it. The designs of component cooling water 20 systems are very different across the plants and emergency 21 service water system, very different from plant to plant. 22 The dependencies in the plants on service water 23 and component cooling water, HPI or the ECCS dependencies, 24 vary considerably in the plants. In some cases, there is a 25 very strong dependence on component cooling water to run the [~') ANN RILEY & ASSOCIATES, LTD.
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(202) 842-0034 l I x _. . -- - - - - - .
- - - - - - . . . - . .. .i
51 1 HPI pumps. In others, there is not. () 2 There's different ways to cool the seals. 3 DR. POWERS: What types of plants or do you have 4 any names of planta that have sensitivity to this and those 5 that don't? 6 MR. CUNNINGHAM: We will come back to that, yes. 7 DR. POWERS: Okay. 8 MR. CUNNINGHAM: There are some that are much more 9 sensitive. You also see that the mechanisms that are 10 available to cool the seals differ among designs. In some 11 plants, component cooling water is the only way that you can 12 cool the seals. In other plants, there are a lot of -- 13 there are alternate ways to cool the seals. 14 In fact, in some designs, they installed new () 15 alternate ways to cool the seals. In addition, the seal 16 performance varies considerably across the plants, across 17 the designs. What we have talked about here so far have 18 been the Westinghouse pumps. We know -- believe it or not, 19 we know far more about the performance of Westinghouse seals 20 under these conditions than we know about some of the other 21 designs. So that's another big variable in this. 22 i So the second piece of Art's analysis then is 23 trying to go through and sort of screen out -- given all of 24 these plant-specific dependencies, are there a class of 25 plants or.a.few plants that might have a particular [D \_) ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
52 1 ' vulnerability,,if.you will, to losses of emergency service
\ 2 water-or component cooling water leading to pump seal G[
3 failure, et' cetera, et cetera, et cetera, and leading to a { 4 fairly high core damage frequency. i 5 What-he'll get to is that you will see for some 6 -designs, there'is'a question at this point, at least under 7 'some' conditions, where you might.have a relatively high core !
~
8 damage frequency for this, but it tends to be fairly plant-
- 9. specific and dependent on some key assumptions on seal 10 performance.
11' .So'with that' kind of introduction, I'm going to 12 -turn it over to Art to go into the gory. detail, if you will. 13 JMR. BUSLIK: As Mark suggested, there were three i 14 basic things here. One is the impact of reactor coolant on () 15 seal-LOCA sequences on the coping analysis for.the station
. 16 blackout-rule and what kind of contribution to the core 17- damage frequency from reactor coolant pump seal LOCAs in 18 station blackout, and also.the contribution from loss of 19 component cooling water or essential service water-induced 20 reactor coolant pump seal LOCAs.
21- I'm going to try to show that the intent'of the 22 station blackout rule, industry average core damage i 23' -frequency from station-blackout of about 1E-to-the-minus- ; 24 five per year is still met. My estimates of core damage ! 25 ~ frequency exclude external events, internal flooding and ANN RILEY & ASSOCIATES, LTD. i O. Court Reporters 1025 Connecticut' Avenue, NW, Suite 1014 i Washington, D.C. 20036 (202) 842-0034'
53 ' 1 fires, and are point estimates. [v) 2 I don't even have a slide on uncertainties, but I 3 can talk about it. I will give scoping estimates of core 4 damage frequency from component cooling water ESW and 5- indicate the nature of the plant-specific considerations 6 which enter into the assessment of the risk from these 7 sequences. 8 I will also indicate where at least -- not in 9 complete detail, we shortened the presentation a little, but 10 some of the plants where you wouldn't expect this to be 11 important. There were 25 such plants that we looked at. 12 Now, when I say Rhodes model, it's a set of paths, 13 so the event tree you saw before, together with the 14 probabilities of those paths and the leak rates associated r 15 with those paths. There are two types of reactor coolant 16 pump seal failures. There was the reactor coolant pump 17 seals popping open. 18 When two-phased flow gets to the seals and then - 19 - and this will take some minutes -- in a Westinghouse pump, 20 something more than ten minutes, maybe 13 minutes, maybe 21 longer, the pressure distribution which tends to open the 22 seal changes and it's possible for the seal to become 23 unstable. 24 The closing force on the top part of the seal ring 25 is smaller than the opening force and normally when it's b ANN RILEY & ASSOCIATES, LTD.
%s' ~ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034-
54 1 stable, the seal will open up a little and this will 2 decrease the opening force and you get a stable situation. 3 But under these circumstances, you can have 4 unstable or bi-stable operation. In bi-stable operation, it 5- opens up and becomes stable at a larger opening. 6 Now, we're concerned about the second stage in 7 Westinghouse pumps and the third stage, according to the 8- Rhoder model, it's his probabilities, the third stage will 9 epen wit.h probability one. { 10 At an earlier time, he thought a probability of a 11 half, 50 percent, but when he looked at it more carefully, 12 he just said one. 13 Now, this is an epistemic, and the probability of 14 a pop-open mode or the second stage is 20 percent. That's 15 an epistemic uncertainty, a state of knowledge. He assumes 16 that all of the seals will pop open if one does. 17 Now, part of his argument for why it would pop 18 open, when, in a test at Montero, it didn't, was that that 19 was a brand new seal and tha.t where the seal can make a 20 difference. There are other aspects. The ratio cf closing 21 force to maximum opening force was greater in the Montero j I 22 seven-inch seal, that it is in the seals that are used in 23 our pumps here. 24 DR. POWERS: So why go through an event tree and
'25- take a probability of pop-open mode to be one.
h b ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 '
55 1 MR. BUSLIK: Instead of 20 percent. ! ( 2 DR. POWERS: Instead of 20 percent, nobody is 3 going to criticize me. 4 MR. BUSLIK: I don't know. This is expert 5 opinion. There was an expert opinion, three experts for 6 NUREG-1150. If you average it, it comes out to be .1564, l 7 and there have been PRAs that have used that number. i 8 But the three experts were somebody from 9 Westinghouse, who gave it a very little likelihood, Dave 10 Rhodes, and Jerry Jackson, who gave a slightly higher 11 estimate than Dave Rhodes did. I'm not an expert in expert
.12 opinion, so I don't know that really.
13 DR. SCHROCK: This is in a NUREG report prepared l 14 by a contractor? A contractor report, yes. Where is Dave ! (~'\ (_) 15 Rhodes? ' 16 MR. BUSLIK: Dave Rhodes is at AECL and -- 17 DR. SCHROCK: Yes, you said that before. 1 18 MR. BUSLIK: Yes. His group is, I guess, well 19 'known as far as behavior of pumps. 20 DR. SCHROCK: But we're thermal hydraulics people, l 21 so he's not so well known to us. 22 MR. BUSLIK: Okay. 23 MR. CUNNINGHAM: Art, before you go off of that, l 24 you make one point right at the end that's worth coming back 25 to. The leak rates that Jerry showed in his event tree were !
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56 1 per pump. () 2 3 MR. BUSLIK: Yes. MR. CUNNINGHAM: The assumption built into this is 4 if you have this occurring in one pump, what's the 5 probability to have it -- 6 MR. BUSLIK: And he assumed that they would all go 7 because of various similarities. 8 MR. CUNNINGHAM: So the leak rates will be much 9 higher than what he's talking about here. 10 MR. BUSLIK: No. For example, in Combustion 11 Engineering analyses, the standard CE, Combustion 12 Engineering Owners Group analysis, they assume independence ) 13 of the pumps, given the same loss of cooling. 14 DR. POWERS: If I look on the decision tree that G k) 15 was shown earlier, what is the probability that that former 16 20 percent that now we've declared to be 100 percent, based 17 on a new expert opinion -- i 18 MR. BUSLIK: That's 182 gallons per minute or 19 maybe 183. 20 DR. POWERS: I'm asking which of the decisions. 21 MR. BUSLIK: You would have to take -- I don't 22 have it in front of me, but there is something -- B-2. B-2 23 is binding or popping open of the second stage seal, and B-24 3.. So nothing fails in the first stage, but B-1 -- but B-2 25 fails, and then B-3 fails. ANN RILEY & ASSOCIATES, LTD. Os Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
57 1 -DR. POWERS: So B-2 is the one that's .2 and B-3 () 2 3 is the one that's 1.0. Right. But, see, number two bind and number three 4 bind, and you get -- here it says 183 gallons per minute. I 5 don't think it really -- 6 MR. CUNNINGHAM: So you have essentially a .2 7 probability of getting to that 183.
'8 DR. POWERS: No, no , no. It's one now. I asked.
9 .I only have-to fight Rhodes and Westinghouse and you, right? 10 DR. SCHROCK: Is there a copy of this NUREG 11 report? Could I have a quick look at that during the lunch i 12 break 1.3ybe? l 13 MR. BUSLIK: I don't have a copy of the NUREG. I 14 have the Appendix A. () 15 DR. SCHROCK: That's what I need, to see Appendix 16 A. I 17 MR. BUSLIK: But it's all probabilistic. You ) i 18 probably won't be that interested in it. 19 DR. SCHROCK: That's what confuses me. You talk 20 about two-phased flow through this narrow passage and then l 21 you tell me it's all probabilistic. Those words are
~22 mutually inconsistent, to me, i
23 MR. BUSLIK: That's right, but you have a model. 24 You can't calculate this exactly and -- 25 DR. SCHROCK: I know how well you can calculate i I [ \ ANN RILEY & ASSOCIATES, LTD, \/
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p ] 58 1 it, that's my field of expertise. That's why I'm here and 2 thats why I have to ask this question. I want to 3 understand what does the thermal-hydraulics consideration 4 have to do with these probabilities that you're putting in j 5 here. . I can't advise on that unless I understand what the 6 thermal-hydraulics considerations are and if you tell me 7 it's embedded as an. Appendix A in a NUREG report from the 8 Canadian contractor, but, on the other hhnd, there's no 9 thermal-hydraulics in it, then I'm even more suspicious. 10 MR. BUSLIK: There was a report -- W-CAP-10541, I i l 11 Rev. 2, discusses the model, to a certain extent. Also -- l
- l. 12 MR. CUNNINGHAM: The thermal-hydraulics?
13 MR. BUSLIK: Yes. There is a chapter on that. l-14 There is also an ETEC report, that I don't have the number 15 for, which goes into it in detail. There's even the source I 16 program for a portion of the calculation and reference to - 17 - you have to do both the -- you have to do both the fluid 18 flow and also the structural part to see how the temperature l 19 changes affect the metal parts and other parts, and there is , l l- 20 a reference to what code was used there for the finite ll l ln 21 element part. 22 That would probably be what would interest you
~
l 23 most. But, see, the conclusion of that was if you do the ! 24 best estimate calculation there, that you don't get any 25 leakage, that the seal face becomes divergent and closes on 1 h d ANN RILEY & ASSOCIATES, LTD. Court Reporters .
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59 1 the inlet to the seal stage. () 2 But as Jerry mentioned, this is based on a lot of 3 assumptions. I don't -- so you don't really know for sure. 4 Let's see. I'm still on the Westinghouse plants. 5 I'm assuming that the operator cools down the plant 6 according to procedures. This will reduce the flow rate if 7 you do get a LOCA, if you depressurize by using the 8 secondary. We're assuming we have aux feedwater available. 9 And under those circumstances, if you look at what Dave 10 Rhodes says there and if you look, for example, at 10541, I 11 think you will get that the core uncovers in about five 12 hours if only the top open mode occurs, without 0-ring 13 failure. 14 If you have the 0-ring failure at two hours, core (O 5
%,/ 15 uncovery occurs in about four hours, with a pop-open mode 16 and the failure occurs at ten minutes, and between four and 17 five hours otherwise. This is from the older calculations.
18 The times might be extended slightly with newer 19 calculations. 20 Basically, that's what I'm assuming, because the 21 chance of getting -- you know, I can't sharpen my pencil on 22 the recovery of off-site power. 23 Now, for non-Westinghouse pumps, there is some 24 evidence that the polymer seals won't fail. They're made of 25 different materials. But here we assume that there is a 20 I \~ ANN RILEY & ASSOCIATES, LTD.
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E ! 60 1 percent chance of a pop-open mode, just as for Westinghouse () 2 pumps, and this is very different than the assumptions made 3 by Byron-Jackson or Bingham-Willowman seal packages in the 4 IPE. 5 They assume a relatively small chance of seal 6 failure., I don't particularly like their model because they 7 have different seal stages. They treat the seal stages as 8 if they were independent things or quasi-independent things, 9 as if you had four diesel generators and use a multiple 10 Greek letter model. I don't like it, because obviously, as 11 someone here pointed out, what happens with one seal affects 12 what happens to the other seal. 13 Now, on the other hand, we don't have much basis 14 for this model here. There was an analytical calculation, O) (, 15 which is referenced in NUREG-CR-4821, which says that the 16 Bingham International second and third stage seals will pop 17 open, according to the analytical calculation, but you don't 18 know what the leak rate will be. It was from less than one 19 gallon per minute to more than 100 gallons per minute, with 20 a nominal predicted leak rate of 50 gallons per minute. 21 That may -- certainly for station blackout, it 22 will make a difference, but it may also make a difference 23 for losses of component cooling water under certain 24 circumstances. l l 25 Also, the analytical predictions seem to be 1 l l ANN RILEY & ASSOCIATES, LTD. j
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61 1 conservative as far as instability threshold, whether it () 2 3 would pop open or not. DR. POWERS: Those things are enormously difficult 4 to know how to respond to, because, yes, when I take a 5 specific mode, maybe they're a little conservative, but they 6 certainly haven't taken all possible modes, so maybe they're 7 not so conservative. 8 MR. BUSLIK: That's right, that's right. 9 Now, we have to ask ourselves, how does this 10 affect -- I think it's 10 CFR 50.63, the station blackout 11 rule. According to that rule, plants were placed into two 12 . categories and any particular plant had to show that it i 13 could cope with the station blackout for four hours or for 14 eight hours. (O,j 15 Just because you don't uncover, according to the 16 Rhodes model, the four-hour plants basically are okay. As 17 far as the eight-hour plants are concerned, we'll have to 18 look at them, because obviously if you did have the seal -- 19 the pop-open mode, that alone will uncover within eight 20 hours. 21 So what was done here was we tried to make a point 22 estimate of the core damage frequency from station blackout, 23 perhaps in the same spirit that it was done in the station 24 blackout rule. And all of the eight-hour plants have 25 alternate AC. For the Turkey Point units, they're available , ANN RILEY & ASSOCIATES, LTD. L Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036
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i I 62
.1 at ten minutes after station blackout. That should be
() 2 3 sufficient to restore cooling to the seals through seal injection. Now, one interesting thing is that I guess perhaps 1 4 { 5 all of these plants followed guidance, I think, of NUMARC, I 6 don't have the number now, and they didn't -- they weren't 7 required to be able to power -- to be able to mitigate a 1 8 LOCA under station blackout. 9 So for the other plants, the other eight-hour 10 plants, it takes one hour to.get alternate AC on and the 11 pop-open mode will occur with 20 percent probability. 12 Now, I originally assumed that they would restore 13 reactor coolant pump seal injection when they were able to i 14 in the Westinghouse plants. But I learned afterwards, I'm ; 15 not sure what they would do under these emergency 16 situations, but normally, if they're recovering from a 17 station blackout, they don't, they will not restore seal 18 injection. The concern is perhaps cracking of the first 19 stage ceramic seal faces, which I don't think would lead to 20 'a leak, but it's a financial problem, and warping of the 21 shaft in Westinghouse pumps. 22 So they don't do that. However, if the pump has 23 the newer 0-rings, we assumed they don't fail, given no pop-24 open mode, and if there is a pop-open mode, it won't matter
. :25 whether they fail or not. -
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63 1 It turns out that all of the plants, all of the ( ) 2 eight-hour plants, except Robinson, have new O-rings. So 3 the only place where I had to make a change numerically was 4 there. 5 So four-hour plants are okay. But you might want 6 to know how much of an increment in risk is there. Well, if 7 we look at the newer information on evaluation of losses of 8 off-site power events from the old AEOD, you find that 9 plants -- I think this was always true -- plants that have 10 losses of off-site power lasting longer than four hours of 11 low frequency, they're usually recovered very rapidly. 12 Grid-related losses of off-site power do not 13 contribute. They used to contribute in the older analysis. 14 Now things are better. Of course, you might say that as we
) 15 go to deregulation, maybe there will be~a short period of 16 time where things -- where it becomes a little bit greater, 17 but that would only be probably three years or so, I would 18 guess, and not very much, as far_as I know.
19 DR. POWERS: There seems to be an awful lot of 20 people worrying about human reliability. I don't know why 21 we would say it's going to be three years before -- 22 MR. BUSLIK: I think it's an opinion somewhat, but 23 -- well, I think because there are strong economic forces. 24 DR. POWERS: I think I agree with you. I think 25 this grid is a liability. It's nonsense. We go through l h' \ss/ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i
e , i 64 i i that about twice and people put it to an end. 1 [ \ 2 MR. BUSLIK: This is just how I calculated. b I 3 used data from an AEOD report. Generally speaking, if you ) l 4 have a two-hour -- if you have a two diesel generator l 5 system, you'll get about .003 for the probability that both ! i' 6 will fail. 7 And you'll come up with 1.3-minus-five per year 8 for the contribution of station blackout induced reactor 9 coolant pump seal LOCA for a typical four-hour coping time 10 plant, with Westinghouse reactor coolant pumps and old O-11 rings. And for the contribution of reactor coolant pump 12 seal LOCA to core damage, that's conservative, because even 13 if you didn't have the LOCA, you should have more than four 14 hours. And it's three-minus-six if the plant has new O-() 15 rings and 75 percent of the plants do have new O-rings now. 16 Some plants say they're going to put them in after 17 they use up their stock of old 0-rings and things like that. ; 18 Westinghouse's position is that there is 19 conservatism in the Rhodes model for a plant which 20 depressurizes, because the softening of the -- the new O-21 rings harden at a higher temperature. The old 0-rings 22 soften. 23 And I don't know -- the new ones, I guess, there 24 is more cross-leaking, I don't know what happens, in the old 25 ones, less cross-leaking. But whatever the reason is, it's
) ANN RILEY & ASSOCIATES, LTD.
(/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
65 1 -- they. soften. But clearly, if you depressurize and reduce () 2 the temperature, you'll -- it seems to me you will decrease 3 the rate of softening and, also, you decrease the pressure, 4 so that the force to blow out the 0-rings is less. 5 So they're assuming that you don't have to worry 6 about it, I think. I don't know. 7 DR. POWERS: Somehow cross-leaking and polymers 8 and these kind of temperature ranges, it seems like a weak 9 straw to me, because it's not just temperature, it's time at ; l 10 that temperature. i 11 MR. BUSLIK: Yes, of course. 12 DR. POWERS: Things don't go at the same timing 13 that you think they are. i 14 MR. BUSLIK: That's right, but they'll -- that's ; r~~ \ 15 right, but if the seals blow out at four hours instead of 16 two hours, you're better off, I think. You have more time 17 to recover, certainly for station blackout. 18 Now, I did some calculations and I came up with
- 19. these results and you can see that the range for the 20 Millstone units is 2E-minus-five per year and the others go 21 down.here. Indian Point, I guess you don't have to worry 22 about grid reliability anymore. It used to be that people 23 were concerned.
24 So as far as station blackout, the conclusions are 25 four-hour plants can still cope with a four-hour plant. The ANN RILEY & ASSOCIATES, LTD. w- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C., 20036 (202). 842-0034
66 , 1 risk isn't particularly large for those plants and that
<x !
(N ,) 2 there is a certain range of risk for the eight-hour plants, 3 but it seems valid to say that on the average, you're still 4 at about 1E-minus-five per year, which was the intent of the 5 station blackout rule. So you could argue that you meet the 6 intent of the station blackout rule. 7 Now, the other concern has to do with loss of 8 component cooling water or loss of essential service water. 9 Now, basically, the Westinghouse pumps and the Byron-Jackson 10 or Bingham International pumps, which are in B&W plants, use 11 redundant methods of cooling the seal; seal injection and 12 component cooling water to a thermal heat exchanger in the 13 pump. 14 But CE plants, except for Palo Verde and perhaps, /~~N ( ,) 15 at one time, Maine Yankee, but I don't think that's of any 16 concern anymore, they don't have seal injection. 17 Now, what were the classic sequences? You lose 18 component cooling water and the high pressure injection 19 pumps required to mitigate the LOCA and the charging pumps 20 are dependent on component cooling water. They could even 21 be the same pumps. 22 Therefore, when you loce component cooling water, 23 you lose the charging pumps. So you've lost seal injection, 24 because you've lost the charging pumps, but because you've 25 lost component cooling water, you've lost cooling through
,w t i ANN RILEY & ASSOCIATES, LTD.
\~/# Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
67 1 the thermal barrier. () 2 So you get some probability of a reactor coolant 3 pump seal.LOCA and you can't mitigate it because the HPI 4 depends, and that's the classic sequence. 5 Also, if you lose ESW, then the component cooling 6 water heats up and you can't -- and the same thing happens. 7 Now, for plants without reactor coolant pump seal 8 injection,'the loss of component cooling water leads 9 directly to the loss of reactor coolant pump seal cooling 10 and'a LOCA occurs, and you may have the HPI depending on 11 component cooling water. 12 Now, there are two, I guess, raised, that usually 13 the HPI can depend on component cooling water. One, the 14 seals of the pump, they require cooling by component cooling A (_) 15 water, and, two, the oil for the motor may require cooling. 16 If it's only the seals that require cooling, then 17 the pump may well be okay when it's pumping for the 18 refueling water, cold water from the refueling water storage 19 tank, but you may have a problem when you go into 20 recirculation. 21 So what kind of variants are there? The charging 22 pumps may not require cooling. The Westinghouse two-loop 23 plants are this category, Ginna, Kewaunee, Port Beach Units I 24 1 and 2, Prairie Island Units 1 and 2. Alternately, the 25 plant may have a backup pump independent of component t
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\ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
68 1 cooling water, ESW to supply seal injection; South Texas, () 2 Catawba, McGuire, the Oconee units. 3 The charging pumps may be cooled by ESW. Then you 4 don't worry about loss of component cooling water, but just 5 loss of ESW that decreases the frequency. 6 There may have been inst alled, recognizing the 7 problem, a backup ccaling system for the charging pumps from ; i 8 the fire water system or other system. Turkey Point Units 3 l 9 and 4, H.B. Robinson, Three Mile Island Unit 1, North Anna 10 and Summer have done this. Some of these were done after 11 they did the IPE. 12 Now, here is Shearon Harris, for example, says 13 that if they have a small break LOCA, they don't need their 14 HPI, they can cool down and use their low pressure injection () 15 system pumps, and as long as they're pumping cold water, 16 they're okay. So what they do is they don't go into 17 recirculation. They have procedures for refilling the 18 refueling water storage tank. 19 One plant said but if the LOCA is sufficiently 20 small, if it's 50 gallons per minute per pump instead of 200 21 gallons per minute per pump or 180, then this plant has 22 containment fan coolers which are independent from component 23 cooling water. So they are argue that they could operate 24 that way. 25 And, of course, if the HPI is cooled by ESW, then b \/# ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
69 1 you don't worry about loss of component cooling water. () 2 Things will also depend on plant-specific 3 configurations. For example, if your component cooling 4 water system is basically a single train system and some 5 sort of leak anywhere in the system fails the whole thing, 6 yov>ve got a problem.. 7 CHAIRMAN WALLIS: You don't get all these 8 individual pumps. 9 MR. BUSLIK: I looked at 39 plants, and 25 of them 10 quickly, because I saw the design features were such as to 11 not be important, and 14 units I looked at -- 12 CHAIRMAN WALLIS: I had this question, in my mind, 13 you're closing a generic safety issue and then the decisions 14 are going to be made on a plant-specific basis and they say () 15 all the plants are different, this may end up with a lot 16 more work than requiring something under a GSI which would 17 fix things across the board. 18 MR. BUSLIK: Except I think if you consider the 19 costs that each plant might have to do, say, to put in an 20 alternate cooling system and added that up compared to the 21 amount of work that would be done here, you would probably 22 find out that you're better off doing the work individually. 23 The problem comes -- 24 CHAIRMAN WALLIS: Did anyone do that? I mean, 25' there was reference also to a cost-benefit analysis or
/ <b ANN RILEY & ASSOCIATES, LTD. \% l' Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i
i 70 , 1 something. Is this just a gut feeling that it would come () 2 out that way or did someone actually formally do it? 3 MR. BUSLIK: We don't know yet. There is another I 4 problem and that is, as you will see here, when you use the j 5 Rhodes model, you can come out with a fairly high frequency, { 6 1.4E-minus-three per year, and that's not including internal 7 flooding and other things. l 8 CHAIRMAN WALLIS: Which one was that? We got some 9 examples in our handout. Nothing -- none of them approached 10 E-minus-three. 11 MR. BUSLIK: That's because you didn't get -- , 12 well, I know which plan it is, but -- l 13 MR. CUNNINGHAM: Art has alluded a couple of times l 14 to a couple of issues that caused this to be fairly high. () 15 One is the design of the component cooling water tending to 16 a minimal design. He's mentioned that a number of the 17 Combustion plants are that way. 18 It's also the dependency or the independence of 19 cooling of the seals, the mechanism for cooling of the 20 seals; again, you see some of the Combustion plants coming 21 up. 22 So the ones that tend to be at the higher range 23' are some of the Combustion plants. 24 MR. BUSLIK: And here our model is most uncertain. 25 So that's a problem. , ANN RILEY & ASSOCIATES, LTD. s Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
a 71 1 MR. CUNNINGHAM: The key piece that Art will come (
) 2 back to is does the pop-open mode in the Rhodes model apply 3 to a combustion pump. That is a key piece of information.
4' If it doesn't, you have low numbers. If it does, then 5 they're high. 6 DR. POWERS: Does Combustion have their own pump 7 or have they bought into somebody else's? 8 MR. BUSLIK: They use the Byron-Jackson pumps. 9 Sometimes, you can have a Byron-Jackson pump with a Bingham 10 International seal package, and one of the plants has that, 11 at least one of the plants has that. So that's basically
- 12. where we are and I guess Sher is going to indicate how this 13 leads to closure.
14 CHAIRMAN WALLIS: Do we understand what the Rhodes 15 model is? 16 DR. POWERS: It's a probabilistic model. 17 DR. KRESS: It's a probabilistic model that has 18 deterministic flow rates in it, depending on the path. 19 CHAIRMAN WALLIS: So the uncertainties are still 20 in the technology and satanical questions. 21 DR. KRESS: No , no. 22 DR. POWERS: It seems to me -- I mean, what I get 23 out of what Art just presented is, A, yes, this thing has 24 become completely a plant-dependent question, that there are 25 lots and lots of plants that have done something, many of [)
\--
AJni RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i
S 72 1 them in response to their IPEs, many of them for other ' s () 2 reasons, and that you have to look for vulnerabilities 3 specifically, and there are some classes where there's a 4 vulnerability in the probabilistic space. 5 MR. CUNNINGHAM: You just gave my summary, in a 6 sense. What Art has done is to look at two types of issues; 7 one, does the resolution of 23, as we see it -- does the 8 path we see now impact what we assumed and looked at in the 9 station blackout rule. 10 MR. BOEHNERT: Didn't the SBO rule require 11 ' verification of the 25 gpm leak rate? 12 MR. CHRIS JACKSON: No. The rule itself did not. 13 MR. BOEHNERT: It just made that assumption? 14 MR. CHRIS JACKSON: Yes. And it should be able to
) 15 cope for a specified period of time. After the rule went 16 . into effect, we were negotiating with industry on 17 implementation. There was an agreement with NUMARC that we I
18 would use 25 gpm and we would take a second look at that 19 when we' resolved Generic Issue 23. 20 Research has done that. That's the look. 21 MR. WERMEIL: What you may be referring to, Paul, 22 is in these safety evaluation reports that were written for 23 the PWRs, there is a statement that says if, as a result of 24 the' resolution of Generic Issue 23, there are concerns or 25 issues that arise with regard to the assumptions that were eb \ /' ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 , Washington, D.C. 20036 l (202) 842-0034 I
73 1 made for resolution of SBO, we would revisit S30 for these bi
\_/
2 plants. 3 That's exactly what Mark is now trying to 4 finalize, I guess, is that this analysis, which is the 5 revisited, and, as a result of that analysis, the conclusion 6 is what was assumed in the evaluations that were done for 7 SBO back in the late '80s are still valid. 8 MR. BOEHNERT: There was nothing hung specifically 9 on 25 gpm then. 10 MR. WERMEIL: no. 11 MR. CHRIS JACKSON: It was a generic letter, 12 Generic Letter 91-7, describes it, and it ;ust says that 13 we'd revi. sit the issue or the issue would be reevaluated, 14 , would have to be reevaluated. A () 15 MR. BOEHNERT: Thank you. 16 MR. CUNNINGHAM: So we had an item in the blackout 17 rule to revisit once we saw where 23 was going. We have 18 done that revisitation. That aspect of 23 resolution does 19 not seem to be a particular issue. 20 DR. POWERS: It seems like the 25 gpm thing 21 doesn't relate to where you're going on 23. 22 MR. CUNNINGHAM: That's right. The other issue l 23 that Art was talking about was the plant-specific nature of 24 the core damage frequency and risk coming from losses of 25 seal cooling leading to LOCAs from losses of component
/^ T ANN RILEY & ASSOCIATES, LTD. %/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
74 1 cooling water and/or emergency service water, because he 2 went through that there are a lot of plant dependencies 3 there that have to be looked at. 4 Art has looked at a number of the plants already 5 and has got a lot of that work done, that Sher will talk 6 about a little bit later. We're going to follow-up and look
.7 at the remaining plants to see is there anything else there.
8 We have seen some plants where you have -- if you 9 assume the Rhodes model applies to other plants, that these 10 other -- to the Bingham pumps, the Byron-Jackson pumps, then 11 you see a class of things that we need to follow up on and 12 look at in more detail, because you could -- it would seem 13 to say that you have relatively high core damage l 14 frequencies, under that assumption and all the other p I C) 15- caveats, if you will. 16 We're going to follow up on that. We're also I
.17 going to try and follow up on trying to get better 18 information on pump seal performance. Again, Sher will come 19- back to this a little bit, but applying the Rhodes model to 20 the -- clearly, the Rhodes model was not developed for 21 Bingham pumps or Byron-Jackson pumps.
22 The question is, okay, can we come up with a i 23 comparable model, and we've had some dialogue, even starting j 24 last week, with EPRI to see is there a mechanism where we 25' can get cooperation with the industry to come up with those ; ANN RILEY & ASSOCIATES, LTD. h/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 f
75 1 types of models. { 2 DR. POWERS: You may not need them. 3 MR. CUNNINGHAM: You may not need them. That's 4 right. And just to be clear, they're not trivial models to 5 develop. You heard Jerry talk about the work they had to go 6 into from Westinghouse's part, on Westinghouse's part and 7 our_ parts to come up with the Rhodes model, if you will. 8 ~It's not a trivial piece of work, by any stretch of the 9 imagination. 10 But that's where we're going with what Art has 11 talked about here. 12 Sher, I guess we can turn it back over to you. 13 CHAIRMAN WALLIS: Maybe this would be a time to
-14 take a break, or where are we in your presentations?
15 MR. BAHADUR: I think a break is a good idea. 16 CHAIRMAN WALLIS: So let's take a break. We will 17 reconvene in 15 minutes, 20 minutes to 11:00. . I 18 [ Recess.] 19 CHAIRMAN WALLIS: We will come back in session and 20 on the record. 21 MR. BAHADUR: You've heard about the pump seals, 22 everything that you wanted to know and some more perhaps. j 23' You also heard the summary of recent work that the staff has ! 24 done on the plant-specific basis. 25 What I am going to do now is to bring all that l 1
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(~/ Court Reporters I 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
76 1 information together and summarize for you as to how it has () 't 2 3 helped the staff to come up with the recommendation that the GSI-23 be closed. 4 The first major consideration -- well, major may 5 be the wrong word, but very significant consideration was 6 the Commission decision not to proceed with rulemaking about 7 four. years back. When the Commission disapproved the 8 proposed rule the staff had prepared, they were very clear 9 in saying there is insufficient basis for gains in safety. 10 They further said that the wide range of plant-11 specific considerations of PWRs,'some of which may require 12 excess work and excess amount of costs which were not 13 commensurate with the safety gained by those actions. 14 So the gist was that for this problem, there is no () 15 generic solution that could be cost beneficial or the staff 16 shoutd continue to see work in this area so that we can come ! 17 up with better analysis on a plant-specific basis. 18 Which brings me to my second thing, which is the 19 limited potential improvement in safety from new 20 requirements; that is, even if the plant, even if the 1 21' proposed rule would have been promulgated, the requirements 22 were such that they wouldn't have brought the safety 23 necessary for this particular issue. 24 In the plant-specific analysis, you have heard 25 from both Mark Cunningham and Art the station blackout b
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ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i
77 1 coping analyais indicated that the intent of the rule is met
,y
( v
) 2 without the plants doing any more activities, any more 3 function on their part.
4 CHAIRMAN WALLIS: This intent of the rule, is that
~
5 -- the rule has specifics in it, as well as the intent. 6 Intent, when I say something meets an intent, it's kind of a 7 qualification which means that, well, it doesn't really meet 8 all the specifics, but, in some overall way, meets some 9 intent. 10 Is that what you're saying? 11 MR. BAHADUR: The intent was for the licensees to 12 evaluate their means for cooling the pump seals and if there ' 13 were deficiencies there or there was some need to make 14 improvement, then to go ahead and make that improvement, O, (_,) 15 whether it was an alternate source of cooling or it was an 16 alternate source of power generation, that was what I meant 17 when I said the intent of the SBO rule was met. l
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18 CHAIRMAN WALLIS: What does the licensee evaluate j i 19 against? Are there some criteria of some sort? 1 20 MR. BAHADUR: What the licensee evaluates against, 1 21 and that's how it's very clear indicated in the analysis 22 that the licensees have done, they just assume a four-hour
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23 station blackout and see their needs for cooling seals for 24 that time and then they have a coping analysis for eight J 25 hours. [ T ANN RILEY & ASSOCIATES, LTD. I 'v l Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 j (202) 842-0034 ;
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78 1 CHAIRMAN WALLIS: And what do they have to show? () s 2 MR. BAHADUR: Before I ask -- l j i 3 CHAIRMAN WALLIS: Do they have to show that the l 4' seals will not fail in that time or what? 5 MR. BAHADUR: Before I ask Jerry to expound on 6 that, my understanding is that both the four-hour coping 7 analysis and the eight-hour scoping analysis are meant to
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8 show that even with the station blackout, the cooling of the 9 seal would not be compromised. 10- CRAIRMAN WALLIS: Is this in a probabilistic sense 11 or some deterministic sense? l 12 MR. BAHADUR: Jerry, do you want to comment? 13 MR. JERRY JACKSON: I think as far as what they ; 14 had to meet on the station blackout, the NUMARC document, it (('N i
,) 15 was the agreement with the staff of how station blackout 16 coping analysis would be handled, in that NUMARC document 17 that the staff approved, they had 25 gpm as the leak rate 18 that would be assumed until Generic Issue 23 had been 19 completed and come up with a final answer.
20 The reason we say it met the intent of the station 21 blackout rule is that although we found, in certain cases, 22 the leak rate -- any failures were a result probably in a 23 leak rate larger than 25 gpm, when we look at the risk 24 analysis, the intent of the station blackout rule, as quoted 25 in the reg analysis for the station blackout rule, and in i ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
79
'l the statement of' considerations that was published in the
'[s_ \/ 2 public record, showed related to the intent of the station f 3 blackout being_that the average plant risk should be in the j 4 neighborhood of one-times-ten-to-the-minus-five. l 4 5- So that's what we meant by meeting the intent of l
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6 the station blackout rule. I 7 CHAIRMAN WALLIS: This is the average part. You
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l 8 have some which are up in the ten-to-the-minus-three.
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9 MR. JERRY JACKSON: No. That's not for station 10 blackout. That's not for station blackout. That was for 11 loss of component cooling water and service water, and that 12 was'just a scoping analysis. Those were not final numbers. j 13 CHAIRMAN WALLIS: So the critical issue has become 4 14 a risk issue and the technical issue is sort of somehow (O ,f 15 being talked away. 16 MR. JERRY JACKSON: The proposed rule that the 17 ' staff put forward in 1994, the Commission ruled on that that 18 the generic fix to it, if you will, to require seal cooling 19 was, of course, voted down. So we're looking at plant-20 specific aspects of it. 21 MR. BAHADUR: Thanks, Jerry. 22 CHAIRMAN WALLIS: So you look at each plant and 23 you do some sort'of' scenario based on your knowledge of how 24 you assess the risk of seals failing and everything is then 25 determined by the CDF you come up with at the end of it all, ft
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80 1 and there are some assumptions made about whether the seals . ,m) 2 (U are cooled or not along the way. 3 Maybe something was said when I wasn't here. 4 MR. BAHADUR: Let me try that. 5 CHAIRMAN WALLIS: I just don't know how -- I don't 6 have a feel for how good this analysis is which is leading 7 to these numbers, which you're saying are okay. 8 MR. BAHADUR: There were two mechanisms for the 9 seal failure that Mark Cunningham had earlier identified, 10 either to do a station blackout and then the second one was 11 where the component cooling water or the essential service 1 12 water system would fail as a result of the seal failure. 13 The staff had done work on both. In the station j 14 blackout analysis, the numbers were shown in the table and () 15 I'm not sure if you were here at the time when Art was 16 making the presentation on the station blackout analysis. 17 We maybe can put that table up once again. 18 Art, would you? 19 MR. CRAIG: While Art is showing the chart, he'll 20 put it back up, I think the bullet on this slide, before 21 station blackout rule, when this issue was identified, loss l 22 of power to the cooling systems for the seals was identified 23 as one way to get seal failure. 24 As a result of improvements made to the plants, including 25 addition of alternate power supplies, improvements in diesel ANN RILEY & ASSOCIATES, LTD. h's/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 o
a 81 1 reliability, the likelihood of losing power to those cooling [)
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2 systems was reduced, and that's what Art is going to look 3 at. And there is some variabilicy in the way the plants did 4 their analyses, whether they're four or eight-hour plants. 5 MR. BUSLIK: What happened was that we found that 6 even if there is a leak, a loss of coolant accident through 7 the reactor coolant pump seals, that the plants could still 8 withstand four-hour station blackout. So there was no 9 problem with the four-hour coping time plants. 10 For the eight-hour plants, we looked at it on each 11 of the eight-hour plants individually and assessed the core 12 damage frequency associated with the reactor coolant pump 13 seal LOCA and found results which ranged from 2E-minus-five 14 per year down to below 1E-minus-six per year. () 15 There are only a few plants here which are above 16 2E-minus-five. 17 CHAIRMAN WALLIS: That's where I was lost. The 18 thing with the F, big F. 19 MR. BUSLIK: Service water, loss of off-site 20 power. 21 CHAIRMAN WALLIS: That is some kind of assessment 22 there. 23 MR. BUSLIK: That's frequency of severe weather 24- loss of off-site power. There is a key down here. 25 CHAIRMAN WALLIS: So that is based on weather j ANN RILEY & ASSOCIATES, LTD. - (_) Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l
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/1 82 l' ~ history, that's right.
() 2 3 MR. BUSLIK: Yes. CHAIRMAN WALLIS: So that's something that 4 probably has a good basis. 5 MR. BUSLIK: Yes. I took it from the AEOD report. 6 You need to know the frequency of exceeding four hours 7 because roughly speaking, if you do get the LOCA on station
'8 blackout, you will uncover'in about four hours.
9 CHAIRMAN WALLIS: We have a test in the next 10 couple of days. 11 MR. BUSLIK: That's true. 12 MR..CRAIG: No , because in severe weather, plants 13 shut down beforehand. 14 MR. BUSLIK: For hurricanes, it is true that they () 15 may shut down a. couple hours beforehand, so the seals will 16 be even cooler and you'll be better off. That's true. It's 17 something which I -- in the closecut memo, I mentioned it. 16 I forgot to mention it-here. 19 DR. SCHROCK: The question of whether there is'a 20 problem at four hours versus eight hours depends directly on 21 the leak rate and through all of this, the determination of 22 the leak rate has been shoved aside and we don't really see 23 any concern on your part about the adequacy of the 24 calculated leak rate. That bothers me, frankly. 25 MR. BUSLIK: The' reason is that there seems to be
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83 1 general. agreement between different people on what that is. r~ 2 Now, they could all be making the same mistake, I don't 3 know. 4 DR. SCHROCK: That's possible. You see, for us, 5 as the thermal-hydraulics subcommittee of the ACRS, 6 reviewing this issue, it seems to me that you need to be 7 giving us a warm feeling that somebody involved in this 8 knows how to calculate this leak rate for this very 9 complicated set of conditions; I mean, very complex geometry 10 and changing geometry during the course of this accident 11 sequence. 12 MR. BUSLIK: There are weaknesses which I think 13 are related to it, but I think generally speaking, people 14 feel that it's relatively conservative.
) 15 MR. JERRY JACKSON: I think if you look at the 16 document that I shared with you there from ETEC, which was 17 our contractor that checked the Westinghouse W-CAP-10541 18 analysis, that was an independent review starting with the 19 drawings and other things that were supplied by 20 Westinghouse. They are thermal-hydraulic calculations of 21 how the seal would behave.
22 DR. SCHROCK: Well, I took a quick look at the 23 equations in that report and it's not comforting. It's a
-24 quick look and I shouldn't --
25 MR. BUSLIK: But it's steady-state, it's not /D ANN RILEY & ASSOCIATES, LTD. ka/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 4
84 1 transient. The two-phase flow model, I think, doesn't () n 2 3 include slip, I'm not sure. I don't know very much about this -- so there are obviously simplifications. How 4 roughness is treated, I don't know. 5 CHAIRMAN NALLIS: What happens is you do go 6 through all this stuff and then when we look at the 7 supporting documents, the warm feeling disappears, and then 8 we're back to some other issue. 9 .We haven't had a chance to look at the thermal-10 hydraulics yet. I 11 DR. SCHROCK: Four hours versus eight hours 12 implies 100 percent difference in the flow rate and I think 13 100 percent uncertainty in the flow rate would not be 14 surprising. () '15 So that's why I say I'm concerned about the 16 quality of the calculated flow rates, the leak rates. 17- CHAIRMAN WALLIS: .It's all calculated. 18 DR. SCHROCK: You seem surprised at 100 percent. 19 The geometry is -- 20 MR. CRAIG: I'm not sure I understand the question 21 is my concern. 22 DR. SCHROCK: Okay. { 23 MR. CRAIG: Is there confusion about what's a 24 four-hour plant and what's an eight-hour plant?
- 25. DR. SCHROCK: No, no. I'm simply using that as an
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S 85 1 example. A 100 percent increase in the flow rate over what q (j 2_ you presume to be the flow rate moves it from one category 3 to the other category. 4 CHAIRMAN WALLIS: Maybe it doesn't matter. 5 DR. SCHROCK: Maybe it doesn't matter. 6 CHAIRMAN WALLIS: Should we worry about the leak 7 rate calculations? 8- MR. CRAIG: The calculations using the Rhodes 9 model were built on extensive work done by Westinghouse and l 10 I think it's fair to say Westinghouse believes that the 11 staff took a good model and make it excessively conservative i 12 by the assumptions that we made, so that the leak rates 13 would be even higher than Westinghouse calculated and based 14 on their tests. (O,/ 15 I think that's a fair assessment. So the leak 16 rates that we used in the Rhodes model we believe are 17 conservative. j i 18 MR. JERRY JACKSON: The leak rates used in the .
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19 Rhodes model are the leak rates calculated by Westinghouse. 20 The ETEC model calculated lower leak rates. Their leak ) 21 rates were somewhat lower. I don't remember all of them. I 22 think the document -- for instance, I compared the two 23- highest leak rates, 480 was the maximum leak rate under 24' Westinghouse; ETEC calculated 440 leak rate. That was a 25 comparison.
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Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 u 1
n. 1 L 86 l 1 DR. SCHROCK: So' excessive conservatism is what () 2 3 gives you confidence that your bottom line is okay, I guess, isn't it? Am I hearing that right? 4 MR. JERRY JACKSON: I think we had faith in the 5 calculations, an independent check of them and the resulting 6 comparison of leak rates, that they were fairly close, and 7 under the complexity involved of a three-stage seal, using 8 all the leak off-lines and all of the dimensions, et cetera, 9 .the change in dimensions of all of those materials, that 10 everything that -- that that was a fairly good comparison in 11 that respect. 12 CHAIRMAN WALLIS: Were there experiments with this 13 particular geometry and these particular materials or is it 14 all somebody's model? () 15 MR. JERRY JACKSON: Westinghouse probably has some 16 information that they have used in developing this 17 proprietary analysis in W-CAP-10541. The one test I could 18 point to is the European test, the French test of the seven-19 inch seal model that was done there as far as what the flow 20 rates would actually be under loss of cooling events, and 21 then I believe there was one other event, which was the -- 22 which we discussed with the Westinghouse Owners Group at our 23 last meeting a few weeks ago, and that was the Sizewell B 24 test. 25 MR. BUSLIK: That just showed that -- 8 ANN RILEY & ASSOCIATES, LTD. Court Reporters
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87 1 MR. JERRY JACKSON: That compared the leak rate at () 2 21 gallon per minute, the no failure leak rate. We don't 3 have events -- we don't have tests where we have failure of 4 various paths that you can look ar. 5 CHAIRMAN WALLIS: So all these estimates of 490 6 gpm are really very hypothetical. They are based on 7 someot.. o model for a very difficult geometry to model. l 8 MR. JERRY JACKSON: Yes. We don't have any big 9 multi-million dollar tests of failures of the seal. 10 MR. CRAIG: And the seal failures that we saw with 11 the earlier Westinghouse design had leak rates of what? 12 MR. JERRY JACKSON: The leak rate for the H.B. 13 Robinson event was estimated at 500 gallons per minute. 14 That was a mechanical failure of the seal, but it could ,s ( ) 15 result in what would be like a limiting leak rate for that 16 seal. So you have an event that sort of compares where 1" maximum leak rates would be. 16 MR. BUSLIK: I believe that if you took out the 19 whole seal package and just had the seal, you'd have major 20 flow resistance. 21 MR. JERRY JACKSON: That's basically what these 22 flow paths show. When you go into a limited failure 23 mechanism, it's back to the hydraulic instabilities that I 24 talked about before. 25 CHAIRMAN WALLIS: If you completely lost the seal, []/ \~_- ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
88 1 the seal is just gone. (N_/-) 2 MR. JERRY JACKSON: That's right. That's right. 3 Yes. If you lose all three stages of seal and they 4 completely open,.then you have that maximum leak rate. 5 That's the most improbable event. 6 CHAIRMAN WALLIS: But you do have some evidence 7 that this actually occurred at H.B. Robinson and that was 8 the flow rate you got, the 500 gpm. 9 MR. JERRY JACKSON: Right. 10 CHAIRMAN WALLIS: I think that's much more -- 11 gives me much more confidence than somebody's model, if it 12 actually happened and was measured, because it's very J 13 difficult to have much confidence in modeling these complex 14 geometries.
) 15 MR. LOUNSBURY: If you don't mind, I'd like to add 16 that the H.B. Robinson seal failure --
17 CHAIRMAN WALLIS: Can you identify yourself, sir? j 18 MR. LOUNSBURY: My name is Dave Lounsbury, from 19 l Public Service Electric & Gas, on the Westinghouse Owners 20 Group. ; 21 That particular failure was not only just the seal
.22 failure, but the leakage was a result of a subsequent 23 restart of the reactor coolant pump. The failures that 24 we're looking at are pretty much static failures that we're 25 concerned with with station blackout.
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1 1 89 1 I want to make sure that it's clear and we 2 understand that restarting that pump is not what we would do 3 for station blackout. That's what induced the 500 gpm. 4 MR. JERRY JACKSON: That's what I mean by a total 5 mechanical failure of the seal. When you restarted it, it's l 6 my understanding they had a complete -- the seal face itself l 7 actually fractured and failed.
)
8 MR. LOUNSBURY: I just wanted to make sure that it l 9 was a restart that was mentioned and it was kind of alluded 10 that it just failed at 500 gpm. i 11 MR. JERRY JACKSON: That was the cause of the !
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12 event, but the result was an event that would show you -- a ' 13 real life event that would show you what would be expected 14 to be a relative to maximum leak-rate. 15 CHAIRMAN WALLIS: I'm just wondering what it is 16 .you hope that this committee will be pleased with or will 17 evaluate. Do you want us to evaluate the thermal-hydraulic 18 model or the risk analysis or what? Tell me, how can we be 19 useful and then make an evaluation of what you're 20 presenting? 21 DR. POWERS: I'll offer an opinion. It appears to 22 me that.you've made some modifications to the existing seal 23- systems in the most vulnerable or best known cases and the 24 staff is attaching some reliability to those, and they'd 25 like to know if they've left something out of that, and is O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suice 1014
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i 9C 1 it reasonable to attach reliability to that. 2 If you accept all those changes as giving you the 3 additional reliability, then it focuses totally on the 4 probabilistic, it seems to me. Relatively little on the 5 details of the Rhodes model. It's more the rest of the 6 stuff, as I see it. 7 MR. JERRY JACKSON: That's right. 8 DR. POWERS: And it boils down to then do we 9 accept that a generic issue is no longer a generic issue if, 10 in fact, there is only a subset of plants, and maybe a 11 peculiar subset, like CE plants, I use that only as an 12 example, I'm not accusing CE, but.CE plants, is that keep it 13 as a generic issue or now it's comething that should be 14 dealt with on a plant-specific basis. 15 That seems to be the essential question here. If 16 you concede that that can be done on a plant-specific basis, 17 then we can close the generic issue, farm this cut to the 18 appropriate project manager, and scratch one off the books. 19 MR. CRAIG: I agree with that. I would add that 20 the Commission decided, in telling us that because it was 21 plant-specific and not to go forward and tell licensees to l' 22 come up with a system to improve reliability of cooling 23 systems in the plants, that that decision has largely been ! l 24 made and the work that Art has done and others looking at it ; 25 basically have gone to define, to the extent that we need to ./ - ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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I l 91 1 look at plants in greater detail, what plants are they. i 2 And of the 39 plants he's looked at, I think there [v') { 3 are three or four, there are 73 PWRs, and he will complete 4 the review I the remainder, and it looks like there will be 5 a number of ' live, six, seven plants that we would then look 6 at in additional detail to give you a sense of what that 7 would mean. 8 DR. POWERS: And you're looking at the five, six, 1 9 seven and you've pretty much covered the PWR. ) 10 MR. CRAIG: Yes. ) 11 DR. POWERS: That's almost exhaustive on PWRs. 12 There would only be about ten that have been looked at at 13 that point. I think what they've focused it down then on I 14 very much is, for thermal hydraulics committee purposes, is 1
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( ,) 15 do you believe that the changes that have been made, new 16 materials, new injection procedures and things like that, ! 17 really get rid of the leak problem that they had in the 18 Westinghouse designs, which, by the way, I think that was a I 19 risk dominant accident for some Westinghouse plants in 20 NUREG-1150. 21 I think the Westinghouse plant came in risk -- 22 MR. BUSLIK: I don't remember that for NUREG-23 1150, but certainly in the early PRAs. 24 DR. POWERS: The early PRAs anyway. That that was 25 a risk dominant sequence. So people have spent a lot of ANN RILEY & ASSOCIATES, LTD. O) (- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 3
i 92 1 time working on this obviously and it would be interesting () 2 to understand better what plants have addressed this 3 explicitly in their IPE and made changes in response to 4 that. 5 I don't know that it's essential to your argument, 6 but it sure would be interesting, if an issue. 7 MR. CRAIG: I think we can present that when we 8 come to the full committee. We can have that. 9 DR. POWERS: It really does boil down to a -- it's 10 going to boil down sooner or later to a probabilistic 11 argument and it's not this probabilistic, it's the 12 availability and redundancy of component cooling water or 13 some other mechanism to handle the problem, and if you drive 14 the probability frequencies down low enough, then I don't () 15 care what cools the component. 16 MR. CRAIG: Right. I would note at this point i l l 17 that if we were deciding to look at this issue today to ; 1 18 determine whether or not it was a generic safety issue and i 19 met the criteria, the old criteria or the new GSI criteria, I 20 it would not pass the test. It would not be identified as a j 21 GSI. 22 MR. BOEHNERT: Do you know how many plants, how 23 many Westinghouse plants had the old versus the new seals? 24 MR. CRAIG: There is one -- to our knowledge, as 25 Art said, there is one Westinghouse plant that has not -- [~ ANN RILEY & ASSOCIATES, LTD. ; \~- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
93 1 MR. BUSLIK: It's 75 percent of the plants have ( 2 the new material. 3 MR. JERRY JACKSON: You're saying only one of the 4 eight-hour plants. 5 MR. BOEHNERT: No , I was asking in general. 6 MR. BUSLIK: It's 75 percent. 7 MR. BOEHNERT: And the others are going to when 8 they get -- 9 DR. POWERS: Until they run out of stock. 10 MR. BOEHNERT: But they haven't committed to this? 11 MR. BUSLIK: No. 12 CHAIRMAN WALLIS: When did this get installed in 13 the 75 percent of the plants? 14 MR. CRAIG: Over a period of years. Q 15 CHAIRMAN WALLIS: Many years? 16 MR. CRAIG: When Westinghouse first started 17 ' selling them the' improved seal package. Do you any of you 18 guys know, does anybody know? 19 MR. BOEHNERT: I vaguely remember sometime in the 20 1980s, as I remember. 21 DR. POWERS: When this thing got identified as a 22 , problem, people jumped all over it. 23; MR. BOEHNERT: Yes, I know, but that didn't come 24; up right away. 25 CHAIRMAN WALLIS: Why so vague about it being put [( - ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
i f l' , 94 1 in.here and there and then some that haven't done it? If ! I' ) 2 it's such a crucial issue, I would think that they would all \ .% ) 3 put it in right away. 4 DR. POWERS: It's a risk issue. 1 l 5 MR. LOUNSBURY: If I can interject a comment. The I 6 answer to your question is they wanted GSI-23 closed before 7 they made a commitment to make that hardware change. 8 DR. POWERS: -A chicken and egg problem. 9 CHAIRMAN WALLIS: -All these things about how the 1 10 regulations work are really not something that the thermal-11 hydraulic committee has much competence to evaluate. I'm
'12 struggling with it. I just don't know what it is I can
<13 contribute to here.
14 The agency seems to be doing some risk arguments b g ,g. 15 and maneuvering around in some regulatory space, which is 16 different from my world. 17 DR. POWERS: I emphasize that if, in fact, they're 18 wrong and the changes that have been made don't affect the 19 reliability.of the seal, then all of this stuff kind of goes 20 into a--- 21 CHAIRMAN WALLIS: Suppose the new material doesn't 22 work. Does it matter? I'm getting the impression maybe it l 23 doesn't matter. 24 DR. POWERS: For a lot of sequences, it doesn't. 25 .If, at Turkey Point, you've got, what, four hardened diesels I} (- ' 7001 RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 i (202) 842-0034 i i
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I 95 1 and I don't know what all they've got there, I suspect ( ) 2 they're not terribly worried about station blackout events. 3 CHAIRMAN WALLIS: I thought that was the thrust 4 that I got from the material I saw before I came here, was 5 that because of other things which had happened which had 6 nothing to do with seals, which has decreased the 7 probabilities of these various events, that really we didn't 8 have to worry about seals anymore. l l 9 So even if it was the old material, it would still l 10 be okay. Is that a good summary or not? 11 MR. CRAIG: I think that's fair, that's right. 12 CHAIRMAN WALLIS: So the seal issue has gone away 13 for reasons that have nothing to do with seals at all. 14 MR. BAHADUR: Let me say this, before John A ( ,) 15 completes his talk. Let me just say that the way I 16 understand, the issue of pump seal failure has not gone away l 17 and that's why the staff is going to do further work. l 18 Where it's going is that the closing of the 19 reactor cooling pump seal failure as a generic issue because 20 the generic solution that the staff has produced at one time 21 did not very clearly indicate that the excessive amount of j 22 money that each and every plant in the country ht.s to spend 23 would commensurate with the safety they would ac'.lieve. 24 CHAIRMAN WALLIS: If that's the isPue, then that's 25 'the-argument that we need to loch at the cost-benefit l ,O' ANN RILEY & ASSOCIATES, LTD. ( Court Rr. porters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842 0034
0 i 1 96 , i 1 analysis and say do we believe that. l 7 m, l g 2 MR. BAHADUR: Yes. 3 CHAIRMAN WALLIS: What is it we have to look at 4 and say do we believe it? And I can't grasp what that is. 5 MR. BAHADUR: Let's see what the numbers say, for l l 6 example. 7 CHAIRMAN WALLIS: It's cost-benefit and that 8 seemed-to be hand-waving. 9 MR. CRAIG: Let me interject, then I've finished 10 my thought. The cost-benefit analysis with the proposed rule 11 was for a generic solution. We have determined that, based 12 on a lot work since the Commission decided that it was not 13 generic, but it was plant-specific, indeed, how correct that l 14 assessment was. 's j 15 As Art's presentation described, coolant pump seal ; 1 16 failure during normal operation in the original GSI has gone 17 away, but based on experience, every day, we just aren't 18 seeing seal failures anymore. 19 There was a concern about what happens during or 20 what would cause the seals to fail. The key cause of seal 21 failures would be loss of. cooling water. The causes for 22 loss of cooling water are the mechanical and the electrical. 23 The implementation of the station blackout rule 24 significantly reduced the likelihood that you were going to 25 lose cooling water that would ultimately then :ause seal O ANN RILEY & ASSOCIATES, LTD. \- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
97 1 failure. So it is related to it, so it caused fail failure. '( ) 2 In addition to station blackout, as the plants did 3 their IPEs, they made changes to reduce the likelihood of 4 loss of seal cooling water. Some plants installed seal 5 cooling systems, as the staff was discussing this proposed 6 rule. 7 So what you have is about 73 PWRs, some of which 8 installed cooling water systems, some of them have installed 9 more power supplies, some of them have installed additional 10 or alternate cooling water sources. So it winnows down from 11 73 to a small number. 12 Because station blackout coping analyces were tied 13 to this issue, we went back and reviewed the impact of the 14 leakage on the SBO coping analysis and concluded that for
) 15 all of the plants, only six, the eight-hour plants, were 16 questionable. And based upon Art's work, we concluded that 17 those six, in fact, meet the station blackout rule, the 18 intent of the blackout rule.
19 So that the seal failure issue has largely gone
- 20. away. There are some plants, because we wanted to look at 21 the loss, potential loss of the cooling water systems, we 22 have gone to look at their IPEs and Art has looked at 39, I 23 think, of the 73 plants. Of those 39 using their IPE data 24 as it was submitted to the staff and using a conservative 25 model for leakage, we have identified so far three plants
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98 1 that we want to contact to understand the assumptions in the lO. 4 2 IPE.
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3 They may have added another power supply, they may 4 have made changes for cooling water systems or where they 5 may not have. When he completes that review, we'll have 6 some number of plants, five, six, seven, I don't think it 7 will be many more than that, and for those plants, we will 8 make a determination as to whether or not plant-specific 9 backfit is appropriate for this issue. 10 That's what we have hoped that the cover memo 11 would say, and I think it goes back to what -- the question 12 of what can the committee look at or confirm. It goes back 13 to the summary that Dr. Powers provided. 14 CHAIRMAN WALLIS: Are you expecting to go to the s ( ,) 15 full ACRS committee next month? 16 MR. BAHADUR: On September 30. 17 CHAIRMAN WALLIS: I think you have to give very 18 crisp summaries like what you just did, John, so that it's 19 clear what's the issue. I'm not sure there is a thermal- I 20 hydraulic issue. 21 MR. CRAIG: At this point, I agree with you. I 22 don't see a thermal-hydraulic issue that's essential to the 23 resolution of 23. 24 DR. POWERS: If I was going to make a 25 redommendation or suggest how to tailor a presentation for I
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99 i 1 in front of the committee, I would spend about five minutes () 2 3 telling them barely there are seals here, barely they did leak, and here is what the problem was before SBO, here is 4 what the probabilities kind of looked like pre-SBO, here is 5 what we have done in -- I mean, here is what the industry 6 has done about it and in a bullet-like fashion, and then 7 here is what we have done in probabilistic space about this 8 and do you believe this, and, bottom line, is this still a 9 generic issue or not. 10 MR. CRAIG: Exactly. 11 DR. POWERS: And we think it is, okay, and do you l'2 agree. That's really the question you're asking. Was there 13 something else that the ACRS had in mind when they yelled 14 about this being a generic issue and my own feeling -- () 15 you've kind of covered the bases here, but you've done it in 16 a way that we didn't expect, but you've done it in a way 17 that the modern approach allows, which is to attack it in 18 any direction that makes sense, and it looks like to me it's 19 been attacked in both directions. 20 The hardware has been fixed and the probabilities 21' have been changed, because the plant configurations have 22 been changed. 23 CHAIRMAN WALLIS: I like that. I think that's 24 very important to say why was this an issue in the past and 25 what has happened to make it go away, and one of them is j
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f 100 1 there are new seals which don't leak in normal operation and () 2 the other is the SBO things and so on. 3 You need to lay that out so that we can see, and 4 then maybe lots of the details that we went through today 5 are relatively important in that picture. 6 MR. CRAIG: Thank you. It will be much better. 7 CHAIRMAN WALLIS: I'm still nervous, as the 8 thermal-hydraulic committee, that when we look at the 9 analysis, we may find the thermal-hydraulic analysis is full 10 of holes. Now, if that's the case, does it matter? 11 MR. CRAIG: I don't think so, at this point, to be 12 honest. 13 CHAIRMAN WALLIS: That would be unfortunate, but 14 it wouldn't make any change. () 15 MR. CRAIG: Art, what is your sense of it? 16 MR. BUSLIK: I think that one issue is the fact 17 that if the leak rates really are indeed much greater, and I 18 don't think we have to have a convincing argument that 19 they're not, then it'would affect station blackout coping 20 analysis. 21 But I think we have to look about that. 22 DR. SCHROCK: Your language is a little confusing, 23 because in the discussion, you've pointed out that there are 24 very conservative determinations of the leak rates, but then 25 as you describe it here on page 18, you talk about staff's ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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I 101 1 best estimate analysis twice. m lv) 2 So evidently your meaning of best estimate is 3 different than the meaning of best estimate as it's used in 4 thermal-hydraulics circles. 5 MR. BUSLIK: It's because I didn't know -- for 6 example, the 0-rings failing in two hours is likely 7 conservative, especially when you depressurize. As far as 8 the actual leak rates that correspond to particular 9 failures, I assume that it's conservative, but I don't know. 10 MR. BAHADUR: I'd like to skip to slide 20, where 11 we have summarized the future work, and I was mentioning 12 before where the staff is recommending the GSI-23 be closed j 13 as a generic issue, and we also recognize that some work 14 needs to be done in certain areas. ( ,) 15 For example, in the development of our RCP seal 16 models, the Commission had expressed concern earlier at the 17 adequacy of the RCP model, although we believe that 18 Westinghouse improved the so-called Rhodes model, it's an 19 adequate probabilistic model, from our point of view, but, 20 of course, if a better probabilistic model would have been 21 developed by somebody else which would apply aptly to their 22 situation, the staff would consider doing that. I 23 As I've said in the slide here, we are pursuing 24 the possibility of long-term development of a seal model 25 with the industry.. The staff does not have budget to do it () \_/ l l ANN RILEY & ASSOCIATES, LTD. Court Reporters I 1025 Connecticut Avenue, NW, Suite 1014 22 84 - b3
F 102 1 within NRC. However, the discussions with EPRI are going on ((~%) 2 and while that discussion goes on about the development of 3 the seal model, the staff is also working with the ASME to 4- make sure that if it's possible, that in their PRA 4 5 standards, a model can be included. 6 CHAIRMAN WALLIS: Why do you need this? You've 7 already dec.ided the things are all right. 8 MR,. BAHADUR: I'm sorry? 9 CHAIRMAN WALLIS: I don't understand -- what are 10 you going to do or what is the payoff from getting better 11 understanding of -- I 12 MR. WERMEIL: I can give you the NRR's 13 perspective, Dr. Wallis. 14 CHAIRMAN WALLIS: Okay.
) 15 MR. WERMEIL: The agency is, as you are well 16 aware, moving to risk-informed regulation. We're in the l 17 process right now of reviewing Part 50, with the intent of 18 risk-informing it. It strikes NRR that if we are to be 19 making-licensing decisions in the risk-informed environment i
20: in the future, the very nature of being risk-informed means 21 or would necessitate enough knowledge and enough information 1 22 to make a proper risk-informed decision. 23 So I view this, and I've made this point to 24 others, as a need for the future, particularly where the new 25 risk-informed rules and the new risk-informed decision-1 I
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E 103 { 1 making for licensing actions becomes the norm.
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[V) If there is indeed a possibility of improving our 3 knowledge and our way of modeling seal failures, because NRR 4 . believes there are definite questions about certain 5 assumptions in the Rhodes model, for example, we would like 6 to have that. As a matter of fact, for quite a few years, 7 NRR has been pressing Research and the industry to help us 8 develop a more knowledgeable, a better model to demonstrate i 1 9 and show what really happens with RCP seals, so that when 10 these sequences show up and we need to make a decision as it 11 arises, we are making as informed a decision as we can. 12 CHAIRMAN WALLIS: So these non-Westinghouse pumps 13 have gone along all this time without any model for their 14 seal failure.
'(
(_j 15 MR. WERMEIL: There.is a model, but, again, it's 16 not necessarily what either we or the industry might believe 17 is necessarily the best model. It is a model. 18 There are questions about it, as there are 19 questions about the current Westinghouse model and the 20 Rhodes model. If there are ways of answering some of these 21 questions, we'd like to answer those questions. That's why 22 this future work has been identified. l l 23 CHAIRMAN WALLIS: Well, this gets to the generic 24 issue that ACRS has and looking at the agency and trying to 25 figure out why it does research, does research in responce l
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) i 104 1 to the need for better'information in order to make better (G
M) 2 decisions, and I think we are struggling with whether there 3- isn't perhaps a better way to get that formulated and meet 4 within the agency, so that it knows when it needs better 5 information, knows how to specify better what that 6 information is, knows the value of the information when it 7 gets it, and that's all. 8 MR. WERMEIL: Yes, that's all. That's exactly 9 right. 10 CHAIRMAN WALLIS: That's another theme. It's not 11 the same theme of this meeting. 12 MR. WERMEIL: It's a larger theme. 13 CHAIRMAN WALLIS: A big theme. 14 MR. BAHADUR: And I just want to repeat here that
) 15 the staff does believe'that the Rhodes model is an 16 appropriate model and it's only if a better model is
- 17. available elsewhere, then the staff, of course, is willing 18 to t'ake that into account.
19 Regarding the plant-specific reviews, I think both 20 Mark -- l 21 CHAIRMAN WALLIS: How do you know it's better? 22 What is your measure of adequacy? These are all things that 23 -- we get these assurances that it's adequate. It's good 24 enough because it has certain accuracy or certain -- what 25 are the measures of how adequate it is? [')
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ti i i 105 1 MR. BAHADUR: I think it's a refinement of a model () 2 3 that you are using currently. If some of the assumptions are more realistic and less conservative, to me, that would 4 be a better model. 5 Right now, the Rhodes model the staff is using is 6 a very conservative model. We have taken the upper bounds 7 of most.of the assumptions and we are applying it wholesale 8 to all the plants. 9 Some people who are not using the Westinghouse 10 seals, for example, may claim that this model is too 11 conservative for them. If they come up with better 12 information, the staff would certainly consider that. 13 MR. WERMEIL: We would view a better model, Dr. 14 Wallis, the same way we would view models in doing thermal-15 hydraulic analysis. If there is additional data that 16 supports the assumptions in the model itself, the model has 17 been subjected to some level of peer review by experts who 18 understand these phenomena, then.it would, in our minds, be 19 a, quote,- better model. 20 CHAIRMAN WALLIS: My interpretation of a better 21 model is that you guys have some questions you're asking 22 which are_ answered better in some way by the model. Peer 23 review, sending it out to professors doesn't answer that. 24 It doesn't answer whether it's better for your purposes. 25 The only way I see a model being better is it's ANN RILEY & ASSOCIATES, LTD. s- } Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
l 106 1 better for use by the NRC for certain purposes, that's my l I ' \ 2 view. It can't be better in the abstract.
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3 MR. BAHADUR: And the essence of that information 4 is more and more conservative decisions you'll have to -- 5 CHAIRMAN WALLIS: I see. So sending it out to 6 professors, you don't know what you're going to do with it - 7 - 8 MR. WERMEIL: Putting it in the right context is 9 important. There is no question, you're right. 10 CHAIRMAN WALLIS: Yes. And it may well be that 11 the Rhodes model is perfectly adequate, but I just have no 12 way of telling. 13 MR. BAHADUR: I skipped over the specific review. 14 Art has talked about it and John alluded to that in his N ('j - 15 summary slide. 16 I'll skip to the last slide, which you don't have 17 a copy of, and it just summarizes what we have been planning 18 on doing. 19 The first thing ic we have -- the staff is 20 recommending that closure of GSI-23 is appropriate. Yes, we 21 realize that further work needs to be done and, therefore, l 22 that's where the -- we have done these specific analyses and l 23 both have indicated that it's not a generic issue. Future 24 work needs to be done to make sure the plant-specific 25 backfit, if it is needed,.can be put to rest. ANN RILEY & ASSOCIATES, LTD.
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i I 107 1 Of course, the last one is that the staff would
,~ - (} 2 keep on working with the industry to develop additional 3 models or to make sure that the ASME standards include some 4 model or the other in the meantime.
5 That completeu the prepared presentation on this 6 issue, if you have some questions. 7 CHAIRMAN WALLIS: We have a presentation from NRR. 8 Do we move on to that or does the committee want to hear 9 -anymore about the Research presentation? I'm ready to move 10 on. I'm just asking my colleagues if they want to. 11 DR. POWERS: I'm sure that in the full committee 12 meeting, we will delve into the absence or uncertainty i 13 analysis and the risk projections. j 1 14 MR. CHRIS JACKSON: I'm Chris Jackson, from NRR.
/,1
( / 15 I was asked to make a presentation on the regulatory i j 16 perspectives associated with the closure of Generic Issue 17 23. 18 With-regard to the licensing issues, as we've 19 discussed a number of times, we consider the station 12 0 blackout issue closed. The current assumptions that are l 21 used will continue to be used. 1 22 With regard to the plant-specific risk, we'll be
._ 2 3 working with Research in the form of a task action plan to 24 resolve the plant-specific aspects of this.
25 With regard to the task action plan, we have hj. ANN RILEY & ASSOCIATES, LTD.
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. I to 108 1 discussed this a number of times, but Research, with NRR, (f 2 will evaluate the risk associated'with the loss of component 3 _ cooling water, loss of service water scenarios, on a plant-4 . specific basis. This assessment will be used as a screen, 5 preliminary indications are that the vast majority of the 6 PWRs will be screened out and we'll be left with a few 7 plants.
8 MR..BOEENERT: When is that task action plan going 9 to be available for us? 10 MR. CHRIS JACKSON: We plan on presenting that on 11 the 30th. 12 MR. CRAIG: It's competing with actually doing the 13 individual plant reviews. But the real focus of this, 14 though, is to get to that subset of the plants, the five, O) (,, 15 the' ten that we talked about,.so that then we have 16 discussions with the licensees. 17_ MR. CHRIS JACKSON: 'For the few plants that are
- 18. not screened out, we're going to have to make decisions on a 19 plant-specific basis. These plants will be evaluated 20 obviously for-further licensing action.
21' DR. POWERS: Would you do a screening analysis 22 . kind of globally and you say, okay, this plant is fine, 23 we're not going to look at it in detail, but had you looked 24 at it in detail, you would have found out that there was 25 some acute vulnerability that you missed'in the screening,
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n - 109 1 do you worry about that kind of thing? f,~~l 2 MR. CRAIG: No, because we have great confidence J 3 that Dr. Buslik -- the reviews that he's doing, and they're 4 largely going on the plant IPEs that we've already reviewed. 5 I think that's the real basis. 6 MR. CHRIS JACKSON: The plants have made some 7 modifications. We want to make sure that all the 8 information is correct. 9 DR. POWERS: That could make for trouble, because 10 they're not guaranteed to reflect the plant as it currently 11 exists. 12 MR. CHRIS JACKSON: Right. With regard to seal
\
13 models, obviously there has been a lot of discussion on the 14 uncertainties associated with the seal models, under
) 15 different pump seal conditions.
16 For future risk-informed actions, at this time, 17- the staff intends to use the Rhodes model for PWRs, for all R18 PWRs, and incorporate it in the PRA standard. 19 DR. POWERS: I don't understand what that means. 20 What PRA standard are we discussing? 21 MR. CHRIS JACKSON: .The one that the ASME is 22 developing. 23 DR. POWERS: If you're incorporating specific 24 models into the PRA standard,.aren't you kind of violating 25 that flexibility that they have built into the standards? ANN RILEY & ASSOCIATES, LTD. (C '} - Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
110 1 .MR. CRAIG: The answer would be yes, if that was () 2 precisely the path. I think Mary Druin and probably Mark 3 have briefed a number of you on what we're doing with ASME 4 an(. A 3ME risk standards. Reactor pump seal models have been 5 identified as a whole in the standard, I think, in the ASME, 6 and what the staff is going to recommend is that the Rhodes 7 model, in fact, be referenced in the standard as one way to 8 do it. 9 So that's the way we're headed. 10 MR. CHRIS JACKSON: Although we feel it should be 11 addressed in the standard and the Rhodes model is an 12 acceptable way to do it. 13 We do want to work with the owners groups and 14 industry to come up with better models. Obviously, the () 15 Rhodes model -- we feel the Rhodes model is an acceptable 1 16 model, but we would love to have a better model and we would 17 appreciate help from industry in developing this model. 18 That's all I have. 19 DR. POWERS: Obviously, the standard is going to 20 be fun reading, isn't it? 21 MR. CHRIS JACKSON: Thank you. 22 DR. POWERS: Ecttom line is you're happy with 23 . this. 24 MR. CHRIS JACKSON: Absolutely. 25 , CRAIRMAN WALLIS: I think what we have now on the ANN RILEY & ASSOCIATES, LTD. O' Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
d 111 1 schedule is a discussion of the subcommittee. ( ) 2 MR. BOEHNERT: That's correct. 3 CHAIRMAN WALLIS: Would any one of my colleagues 4 like to start that off? 5 DR. POWERS: I guess I told you I would outline a 6 presentation, but I think we need to arm our PRA -- our 7 colleagues of the PRA persuasion well with both the appendix 8 and the Rhodes model, and Art's presentation. I think we'd 9 better be prepared for some interrogation on uncertainties. 10 I think the thermal-hydraulics committee has to 11 come in and say, gee, we sure are enthusiastic, we're 12 unenthusiastic, one way or another, about the hardware 13 changes that have been made and the confidence which we have 14 that they're going to work. A (_) 15 DR. KRESS: Do you mean the new seal material? 16 DR. POWERS: The new seal materials and the 17 injection modes and things like that. 18 CHAIRMAN WALLIS: We didn't really hear much about 19 that, so I don't have a basis for saying I bless the new 20 ~ material. I don't really have a basis for blessing the 21 Rhodes model. I feel like a member of an audience rather 22 than a participant. 1 23 So I feel that we're going to come in and say, l 24 look, this is not really a thermal-hydraulic issue, it's all 25 the argument is going to be based on risk, here you are l C)
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112 1 colleagues of the PRA persuasion, go to work. I think we've () 2 3 helped you to develop a shorter presentation, and that's always a good thing to have a rehearsal like this. 4 But I definitely myself am grasping, if there are 5 any technical issues, and if there are, they didn't really 6 get highlighted for me. 7 DR. KRESS: I want to asscre that these flow rates 8 or the various paths of the failures are conservatively ; 9 developed, and it might be worthwhile for us to make an 10 assessment of whether that's really true, if we think that's 11 conservative, and if it's cor.servative, then I think the 12 question of how conservative might enter in and how 13 conservative do you need to be to make the decisions that 14 you make on it. () 15 CHAIRMAN WALLIS: That's what bothers me, and I've 16 said it a few times, is that we didn't -- even when I was 17 away, we still didn't have a presentation of them all. So 18 we don't know what it is. We don't really know much about 19 the new seals and the materials and so on, so we're not 20 really able to evaluate them, except experience shows that 21 they don't leak in normal operation. That seems to be the 22 biggest thing. 23 DR. KRESS: That's a big item. 24 CHAIRMAN WALLIS: But I don't know how they would 25 perform in abnormal operation. I don't have a basis for O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
i U i 113 1_ knowing how they would respond to not being cooled. () 2 I have no basis for evaluating the leak rate 3 models. I haven't seen them. 4 DR. SCHROCK: The question is should we take the 5 time to look at them. 6 CHAIRMAN WALLIS: If we found that we didn't like 7 them, then we don't -- we're in some new territory which we 8 haven't covered yet. 9 So the thing is should we leave them alone or 10 should we stir up this dog that might bite something. Do 11 you have time, Virgil, to look at these models? 12 DR. SCHROCK: It's a hard one to answer because my 13 quick -- my quick look at this indicates the things that I 14 gave to Paul here would suffice and that's something I could 15 probably do in a day or two, but if getting into it raises 16 more questions than it answers, then other references would 17 have to be consulted, and I don't know how to go about 18 getting them, if that is the case, or even identifying what 19 they are. 20 CHAIRMAN WALLIS: So your argument is based on 21 risk, the risk has gone down, before this was a big issue, ! 22 and the risk has gone down and there are several reasons. 23 One is new seal material, which is better, but I don't know 24 that.we have evidence for how it's better and real 25 quantification of how the risk has been reduced as a result [kJ-) ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
a d 114 1 of the new material. /~ '(_,T
/ 2 MR. BUSLIK: There have been tests on the new 3 material which Jerry Jackson knows about, which indicate 4 that it does -- that it is better than the older material.
5 CHAIRMAN WALLIS: Yes, but does it reduce the risk 6 by a factor of ten? 7 MR. JERRY JACKSON: I believe these tests were 8 like for 30 hours, that the gap is expected to be seen in 9 the loss of cooling event for a Westinghouse seal, at the 10 delta Ps that were expected for those gaps, and at the 11 temperatures. I think that's the neighborhood of the length 12 of time that they were tested and they didn't fail under 13 those conditions. 14 MR. BUSLIK: And this didn't take credit for the
) 15 cool-down. We don't know how much --
16 CHAIRMAN WALLIS: All this is hearsay. We haven't 17 seen a clear exposition of what the new seals do which makes 18 the risk less. If you're going to hang part of your 19 presentation on the new seal material reducing the risk and 20 this is going to be a quantitative thing, then I think it 21 needs some kind of logical justification, other than just 22 saying a qualitative hearsay type argument. 23 The other argument, which I think you're in much better 24 shape, is that there have been lots of changes in these 25 plants in terms of diesels and pipes and pumps and stuff, I I ANN RILEY & ASSOCIATES, LTD. \- ' Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 b i
l-l 1 i 115 1 which are things you can actually point to which are real
) 2 and probably the risk assessment associated with those is 3 pretty solid.
4 I don't know that there has been any improvement 5 in the thermal-hydraulics. The Rhodes model is what you had 6 before, isn't it? There.is no before and after with 7 thermal-hydraulics. So none of your argument that things 8 are better now than they were before depends on any kind of 9 thermal-hydraulic model. So we could say that this 10 committee has nothing to say. 11 We can't say anything about seals because we don't 12 know what they are, haven't seen any evidence. We can't say 13 anything about thermal-hydraulics, because it's not part of . 14 the argument, and we haven't seen it anyway. All of your
) 15 argument is based on risk and various other changes in the 16 plants.
17 The argument for making the generic issue go away 18 because it's really a plant-specific issue is something 19 which I think the whole committee needs to hear. It's not 20 really a thermal-hydraulic issue and it's probably true. 21 I'm just listening and it sounds to me as if you 22 have good arguments there. 23 DR. POWERS: The weakness right now in the 24 probabilistic analysis is really the uncertainty portion. 25 MR. BUSLIK: As far as what the new material does ( i ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 L
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!I 116 1 l
1 to reduce the risk, if the 0-rings don't fail, then the only n f i
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i 2 failure mode is the pop, and it's only 20 percent
- 3. likelihood.
4 DR. POWERS: But that's a harsh expert judgment 20 j l 5 percent. ' 6 MR. BUSLIK: That's right. l 7 DR. POWERS: And that's a thin reed to grab a hold 8 of. 9 CHAIRMAN WALLIS: Somebody's guess? Somebody's i 10 guess. i 11 DR. POWERS: Wild-ass guess, yes. l 12 CHAIRMAN WALLIS: Well, I don't think we should 13 make wild-ass guesses dealing with nuclear safety. i 14 DR. POWERS: On the other hand, if you can show ( 15 that it makes no difference whether you take the educated 16 knowledgeable engineering judgment -- 17 DR. KRESS: Which was what, 40 percent? 18 DR. POWERS: No , that was the 20 percent. 19 DR. KRESS: That was the 20 percent. 20 DR. POWERS: Or the wild man 100 percent, then it doesn't 21 change the risk very much, or 80 percent or 60 percent, and ; i 22 it doesn't change the risk very much -- 23 DR. KRESS: Then you've got something to hang your 24 hat on. 25 DR. POWERS: Then I really don't see any reason to
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1 i 117 1 devote heroic efforts to refining 20 percent to .154. () 2 CHAIRMAN WALLIS: Yes, but I have a complaint 3 about too many judgment calls, about somebody guessing 4 something, somebody guessing something. Soon you have a 5 pretty good pile of cards, you move one and the whole thing 6 falls down, because it's not based on the logical structure 7 that I'd like to see. 8 DR. POWERS: If the risk assessment is well done, 9 and it seems like it has been done, that should be something 10 that they can test, is how sensitive are you to each of the 11 -- to jiggling each of the cards. 12 Now, much more difficult is always the question - 13 - you know, as soon as you tell somebody I went through and 14 looked at what happened and I jiggled each one of these () 15 cards and not much changed, the next question they're going 16 to ask is what happened if you do two at a time. 17 DR. KRESS: In a different direction. 18 DR. POWERS: I mean, still, there is a limit to 19 those questions when you're dealing with these kinds of risk 20 numbers. We just bought off on four-times-ten-to-the-minus-21 seventh and I signed it right here, so obviously there's a 22 threshold of where risk and pain cross. 23 CHAIRMAN WALLIS: When you present these numbers, 24 these 1E-minus-five and so on, I think you ought to show a 25 breakdown which says that this contribution is due to the
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s . O ! 118 1 fact that they've done something under the station blackout () 2 and this contribution is because they've done something with 3 the diesels and something, this contribution is that, and it 4 will turn out perhaps that the contribution from the 5 , original question, which is about the seals, is really very 6 small. 7 I don't know, but I suspect how that's going to 8 come up. So this would explain why we didn't go in a great 9 deal of detail into looking at these seals and the technical 10 basis for making decisions about them. 11 DR. KRESS: I think there is still an issue of 12 looking at the seals or what I would call the non-13 Westinghouse pumps. 14 MR. BOEHNERT: Yes. ( ,) 15 DR. KRESS: I think that one is still open. 16 CHAIRMAN WALLIS: There is no mode. 17 MR. BOEHNERT: That's what I mean. 18 DR. KRESS: If they can define it with the Rhodes 19 model, then they have a similarity and it may be useful. 20 CHAIRMAN WALLIS: How can you do that? How can 21 you apply a Rhodes model to a different seal? 22 ha. BOEHNERT: Is it generic? 23 DR. KRESS: You'd have to apply the event tree to 24 a different sequence. It's the same concept. 25 CHAIRMAN WALLIS: If the other one looks similar,
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N l i. 119 i l' you could say,.well, it's the same sort of technical i (G) 2 questions, the same kind of assumptions should lead to the 3 same kind of a model. 4 DR. KRESS: Yes. 5 CHAIRMAN WALLIS: But if it's something very ) 6 different, then you would say, well, this model doesn't 7 apply. 8 MR. BAHADUR: If the failure modes and the seals ; 9 are similar, the hardware, and if the claim is that the I 10 other seals are more robust, then it's Westinghouse, and if
)
11 the staff's presumption is that the Rhodes model is adequate 12 and very conservative, then, yes, you can apply that, but 13 you may not get realistic results. i r 14 But what you are getting is a warm feeling that in j qT ,, 15 spite of all these assumptions, if you're getting the risk 16 values as well as you are. The chances are if you were to 17 look that into detail, I think the values would be low. 18 CHAIRMAN WALLIS: I don't get a warm feeling from 19 these hearsay type arguments at all. The argument that it's 20 a more robust materia; or something, more robust design, I
-21 don't know what that mehnu.
22 MR. BUSLIK: Okay. I don't know -- I'm not quite 23 -- the maximum leak rate from the non-Westinghouse pumps is 24 less. It's perhaps 200 or 220 gallons per minute. - 25 CHAIRMAN WALLIS: Isn't all you need to do to ANN RILEY & ASSOCIATES, LTD. v Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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i 120 J 1 calculate the worst case, the worst leak rate you could get, () 2 with some conservative assumptions? l 3 MR. BUSLIK: We basically used almost that. I 4 believe it's 180 gallons per minute. The probability of 20 5 percent, that this leak rate will occur, will probably be a 6 lower leak rate. The probability of 20 percent, I think it 7 comes from the fact that the balance ratio is at least as 8 good for these other pumps. Then we feel that the pop-open 9 mode wculd be no more likely than for a Westinghouse pump. 10 CHAIRMAN WALLIS: When they calculate the leak 11 rate, they assume that it's a single-phase water leak? 12 MR. BUSLIK: The leak rate is -- when they say 13 gallons per minute, I'm not really clear what is meant. 14 It's some standard -- l 15 CHAIRMAN WALLIS: But the most conservative 16 assumption would be to say it comes out as pure water and it i 17 flashes somewhere downstream. 18 MR. JERRY JACKSON: We don't have a detailed 1 19 thermal-hydraulic analysis of the seals like was done with 20 the Westinghouse W-CAP-10541 or our analysis of that, but 21 AECL, our contractor, has done some limited analysis of the 22 Byron-Jackson seal and they came up with a leak rate, j 23 considering the exact conditions, with the maximum opening 24 of the seals, and that number was 200 gallons per minute. 25 CHAIRMAN WALLIS: But they have a two-phase model? i f'N
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121 1- MR.' JERRY JACKSON: Right. 2 DR. SCHROCK: Reciting of the leak rate in gallons 3 .per minute suggests that you don't really care much about the precision of the number, because if you're talking about
~
.4 5 gallons'of hot water in the reactor versus gallons of cold 6 water in your seal coolant system, you've got more than a 7 factor of two in the densities.
8 DR. KRESS: 'Their concern is for gallons of RCS 9 water. 10 MR. BUSLIK: I looked at some numbers, because I 11 never understood whether they converted, say, 70 degrees 12 Fahrenheit. I think in these cases, they're talking about l 13 the mass of water that you would have if it was 500 degrees 14 Fahrenheit.
- l. 15 CHAIRMAN WALLIS': So you don't know which one it 16 is. It's very'-- it makes it a factor of two difference.
- 17. MR. BUSLIK: That's what I -- I looked at a curve l
18 and I was curious, I calculated what the density was, l 19 because I was able to get the pounds, mass and the other, 20 and it was at 550 degrees Fahrenheit. l 21 MR. JERRY JACKSON: That was converted as a number 1 , 22 to compare. They actually calculated it and did it using 23 the densities and temperatures and calculated in pounds, 1 l 24 mass. They didn't really calculate the gallons. I i l 25 They did the calculation for the Byron-Jackson ANN RILEY & ASSOCIATES, LTD. l
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0 122 1 . pump that's used in the AECL system and that had some {) 2 different conditions, different temperatures and pressures.
-3 So we had to some ratio and we're not claiming that this is 4 the exact number, but it gives us a relationship between 5 maximums and the different pumps.
6 If you compare the maximum of 480 gallons per 7 minute to the Westinghouse seal, it looks like the Byron-8 Jackson seal would be about half of that maximum leak rate.
.9 That's all the precision that we can claim at this 10 time, because we haven't done that much work on the other 11 seals.
12 MR. BUSLIK: Basically, what I used was given a 13 certain -- you can take it off the curve, if you have a 300 14 gallon per minute leak rate, and how long is the time to 15 core uncovery. , 1 16 CRAIRMAN WALLIS: So I'm going to say in my 17 introduction to you folks when you come before the committee 18 that this is really a risk issue rather than a thermal-19 . hydraulic issue and that we look to you to make that case. 20 I just hope something doesn't emerge when we start looking 21 at the thermal-hydraulics. 22 They'd talk to Schrock and look at the thermal-23 hydraulics and say, gee whiz, this isn't conservative, it 24 could easily be.twice the leak rate that these guys are 25 predicting. Would that be a problem for you, if, say, it ANN RILEY & ASSOCIATES, LTD. O- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 : Washington, D.C. 20036 (202) 842-0034 z - i
123 1 turned out to be a thousand gallons per minute? When do you ew (J) 2 worry? How much does it have to be before you worry? 3 MR. CRAIG: It depends on where it is and the 4 assumption in the model, et cetera. If you see something 5 like that, we'd like to know about it real quick. 6 CHAIRMAN WALLIS: Don't you have an idea of where 7 the cliff is or how much leak can you stand and still go 8 with your risk arguments and be okay? 9 DR. POWERS: I think they run into -- 10 MR. CUNNINGHAM: There is probably no cliff. It 11 just -- if the rates are higher and higher, then the time to 12 core uncovery becomes shorter and shorter. 13 CHAIRMAN WALLIS: So when would you worry? I'd 14 also like to know how far you are from the leak rate at /G
,) 15 which you would worry.
16 MR. CRAIG: How far off can the Rhodes model be l 17 before we'd want to -- i 18 MR. BUSLIK: Well, the times to core uncovery will 19 be less. As far as station blackout is concerned, if the - 20 - if you don't get to -- the problem is if it becomes too - 21 - if it goes up to 360 gallons per minute instead of 180 22 gallons per minute and you uncover in two hours. l 23 CHAIRMAN WALLIS: You have a coping problem. 24 MR. BUSLIK: You have a coping problem and you 25 have, also, the fact that it may be that things other than [] \/ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 c
F i 124 1 severe weather become important. 2 CHAIRMAN.WALLIS: Okay. 3 DR. POWERS: I see what you're saying. 4 CHAIRMAN WALLIS: You're reminding me of something 5 that I picked up, I read attachment two and it said the 6 staff assumed operator action is taken to cool the plant 7 down after seal failure. 8 MR. BUSLIK: This is -- it shouldn't say after 9 seal failure. It's been -- after loss of coolant. 10 CHAIRMAN WALLIS: It said core uncovery around 11 five hours. 12 MR. BUSLIK: No. Even if the operator is to cool 13- down beginning at a certain time when he is in station 14 blackout, and it has nothing to do with whether he has -- he () 15 wants to try to prevent the seal failure. It has nothing to 16 do with whether a seal failure occurs or not. It will l 17 extend the time to core uncovery because he does this if he 18 gets a LOCA. 19 I'm not rare exactly what time he starts. Under 20 the assumptions, perhaps a half hour. 21 CHAIRMAN WALLIS: He has to do the right thing. ) 22 MR. BUSLIK: He has to do the right thing, but 23 there are procedures and he is supposed to do that. 24 CHAIRMAN WALLIS: I'm just thinking of TMI. Is 25 there some way that the seal failure would make it more [~') \s ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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i 1 i I 125 q 1 vulnerable to him doing the wrong thing? Does it make his (RJ~s) . 2 job more. difficult, so he might likely make the wrong l 3 decision? l 4 MR. BUSLIK: I don't see how. 5 CHAIRMAN WALLIS: It seems it should be in your j 1 6 -risk analysis, assuming the operator does the right thing. 7 DR. POWERS: A risk analysis would have it.
]
8 MR. BUSLIK: It's going to be small. 9 DR. POWERS: Yes. It's going to be a ten-to-the-10 minus-three kind of thing, because it's proceduralized. 11 MR. BUSLIK: That's right. 12 DR. POWERS: And that's a pretty obvious procedure 13 to follow. 14 MR. BUSLIK: It's an obvious procedure and they 7"'S l 'q_,/ 15 don't assume that he starts before a half hour or so. ! l 16 CHAIRMAN WALLIS: I read this. I was a bit 17 puzzled here. It says there is a 100 percent chance of core i 18 uncovery between four and five hours if unqualified 0-rings i 19 are used. Now, I thought core uncovery was a big no-no, yet ' 20 here is 100 percent chance of it happening. 21 MR. BUSLIK: Yes, but you have to consider the 22 chances that you will be in the situation and that you -- 23 you have core uncovery in four or five hours assuming that, 24 in this. case, first of all, you have to have the O-rings 25 fail, which was the station blackout. And secondly, you (\~)
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! i 126 1 have'not.to have recovered your capability to mitigate the 2 .LOCA'before core uncovery.
3 CHAIRMAN WALLIS: All of this is some
, 4 probabilistic. sequence of' things.
.5' LMR. BUSLIK: Yes.
6 CHAIRMAN WALLIS: This statement here of 100 7 percent chance is'only given all these other things. So 8 what looks like a' bad thing is actually mitigated by a lot 9 :of things which aren't in this particular paragraph. 10 MR. CUNNINGHAM: Given a whole series of events, 11 there is a conditional probability of one. 12 CHAIRMAN WALLIS: But just taken out of context, 13 when I read this, I say, well, should I worry about it, and 14 .I say probably yes. ( 15 MR. BUSLIK: I thought we had added something 16 there, but I guess we didn't. 17 CHAIRMAN WALLIS: It's almost 12:00. We can I
.18 ' finish at 12:00. . We don't see you folks again until next
.19 month sometime.
1 20 MR. CRAIG: The 30th. 21 CHAIRMAN WALLIS: When the real presentation is , i
- 22. made. We'll want the one that really matters. In the 23 ' interim, if-we' discover something,-we may get back to you, 2
.4 if we discover something in our reading, because I'm not
- 25 sure we're going-to just stop here.
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.1 MR. CRAIG: Please do. And if you see a reference
() 2
'3 to information and you want another document, we'll get it to you very quickly. Won't we, Jerry?
4 CHAIRMAN WALLIS: Very quickly is not adequate. I
.5 want something like UPS or guaranteed 12 hour delivery.
6 DR. KRESS: That's what very quickly means. 7 CHAIRMAN WALLIS: It's now noon. We will break 8 for lunch. We'll come'back at 1:00, 9 [Whereupon, at 12:00 p.m., the meeting was 10 recessed, to reconvene at 1:00 p.m., this same day.] 11 12 13 14 f3 (_) 15 16 17 1 18 ' 19 1 l 20 21 22 23 , 24' 25 1
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128 1 AFTERNOON SESSION () 2 (1:00 p.m.) 3 CHAIRMAN WALLIS: We'll come back into session. 4 We are looking forward to this afternoon. We hope to hear 5 some great things and invite Farouk Eltawila to tell us 6 those great things. 7 MR. ELTAWILA: Good afternoon. I think I'll just
'8 give you an outline of my presentation here and I structured 9 the presentation based on a discussion I had with Professor 10 Wallis, so I am going to start with responding to some of 11 the comments on the ACRS views of thermal-hydraulic research 12 that was reported in NUREG-1365, I believe, talk about the 13 budget reduction impact, and NRC's strategic goal and then 14 provide the linkage between the NRC's strategic goal and the O) i s 15 thermal-hydraulic research. In the area of code development 16 I am going to talk about the top user needs and code 17 consolidation effort in a very brief summary, the separate 18 effects tests and chen some concluding remarks.
19 If I did have enough abuse from you, I might come 20 back at the end of the day tomorrow and talk about summary 21 because I am on the agenda again, so -- 22 DR. POWERS: I think we ought not dismiss the need 23 for code consolidation in a summary fashion. I think we 24 have to drive home to ourselves and then to the rest of the 25- world that this really is -- we are talking about codes that ,9 ANN RILEY & ASSOCIATES, LTD. \> Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 , (202) 842-0034 i
f 1 129 1 are used by the line organizations, NRC. We are talking about what, three or four? [) v 2 3 MR. ELTAWILA: There were four, yes. 4 DR. POWERS: Four codes of various levels of 5 approximation, various levels of sophistication, all highly 6 peculiar -- that is, if I am a RAMONA user, I don't go over , 1 7 and use TRAC, and vice versa -- that the level of l 8 approximations are different in these various codes. l 9 What you are trying to do in the code 10 consolidation is give a uniform code kind of a consistent ! 11 level of approximation that can be applicable to all the ! { 12 reactor types, all the jobs that NRC needs to do, and one l 13 where you can train a set of users so they can switch among i 14 plant systems with some facility. I mean I den't think they i () 15 can instantly change from a BWR to a PWR but the code 16 structure and what-not is not one of the barriers to 17 switching between those two units. This seems like a 18 crucial -- 19 MR. ELTAWILA: That is very well put, and we'll 20 capture that in our viewgraphs in the future. I'm 21 serious -- 22 DR. POWERS: I am too. I think it is absolutely 23 crucial that people understand we are not talking about a 24 code that is used off in a National laboratories or for 25 whatever games we like to play in the National laboratories D ANN RILEY & ASSOCIATES, LTD, [O Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 L a e
130 1 to talk about one that is used for licensing activities. () 2 MR. ELTAWILA: That's right. 3 DR. POWERS: And it is crucial to the mission of 4 the NRC and right now for a variety of reasons, most of 5 which I think are good, we have various types of codes. We 6 gained whatever it is we were gaining by having a diversity 7 of codes and now we are talking about consolidating it down 8 and looking for that cost savings but more importantly 9 looking to have kind a uniform level of treatment for all 10 the codes, and we have the advantages of being able to move 11 personnel around as we go through transitions in personnel, 12 which we know we are going to have. 13 MR. ELTAWILA: In our reduction, which is 14 happening. I agree with you. () 15 I think I made a mistake. The NUREG is NUREG-16 1655 and the Volume I of that NUREG, the ACRS made comments 17 that the ACRS does not see pressing need for NRC to maintain 18 support for the large-scale thermal-hydraulic test 19 facilities such as PUMA and APEX, and we have two reasons 20 for this conclusion. 21 One of them is the facilities have served their 22 purposes and the second reason, that is on the second page, 23 that testing to validate the consolidated code is very 24 likely.to come from cooperative international research 25 ventures. ANN RILEY & ASSOCIATES, LTD. x Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
0 I c 131 1 I would like to address both of these items. Li 2 With regard to the view that the facilities have 3 served their purpose, I agree with you if you consider the 4 purpose of the facility was the certification of the AP600 5 or what we intended to use the PUMA for, for the SBWR, the , 6 statement is a correct statement, but however we have Item 7 5, a new mission for both the APEX facility and the PUMA 8 test facility which are related to code requirements, so we 9 are hoping that we will be using this facility to provide 10 more accurate and extensive data for model improvements. 11 I think you are here today and tomorrow. There 12 are a lot of model deficiencies and even although these are 13 integral test facilities, you don't improve models from 14 these facilities but you improve the models from the () 15 separate effect' test facilities and you want to go back to 16 the integral test facility to get information to validate 17 this model. The problem is that some of the old information 18 we are finding that they are not existing and the data did 19 not, really were not using the most up to date 20 instrumentation, so the old experimental integral test 21- facilities are limited. 22 As far as the international -- I will get to the j 1 23 next phase -- next viewgraphs. With regard to the APEX
]
24 facility, we have for Fiscal Year 2000 and actually starting 25 this fiscal year we are starting defining some tests that we O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 '
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l t i 132 1 need to do for the PTS issue resolution, pressurized thermal ( ). 2 shock, in particular that we want to look at the condition 3 that is conducive for PTS. 4 Some of the decisions that were made in the early 5 '80s were made based on an analysis using the TRAC-P code, 6 which concluded that there is flow stagnation. Another code 7 did not predict flow stagnation. We know that both codes 8 are wrong because they are not supposed to predict this 9 phenomenon so what we would like to do is to try to look at 10 the condition in the integral test facility like the. APEX 11 facility, particularly for plants -- we'll start with plants 12 that they have two cold leg per hot leg and we'll look at 13 the condition that can lead into stagnation. 14 What happened in some of the tests that we 15 observed at the APEX facility that when one loop stagnates, 16 the other loop continues to circulate, so we want to study 17 the effect of the second loop and the second leg in the same 18 loop, circulation on the overall mixing in the downcomer, 19 and we would like to see the effect of that and see if we 20- are~ going to get flow stagnation as an issue.
.21 In addition to that, we want to look at the 22- temperature distribution in the downcomer and in the cold 23 leg.
24 CHAIRMAN WALLIS: You think that codes predict 25 this? j ANN RILEY & ASSOCIATES, LTD. \d. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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5 ! 133 1 MR. ELTAWILA: Say that again? No , the codes will () 2 3 not predict this -- CHAIRMAN WALLIS: But you are going to -- data 4 will be used to assess code prediction of thermal-hydraulic 5 behavior in the downcomer region. 6 Don't you want a greater degree of fineness and 7 detail than the codes can currently predict? 8 MR. ELTAWILA: What we want, to use the code for 9 assessment, not for assessing'the stratification itself as , l 10 much as assessing the condition that exists pre- l l 11 stratification in the cold leg and the effect of the plume. 12 If we see that this condition is going to get into 13 the experiment, what we will use the integral test facility j 14 is to assess the overall code behavior, but we have to go to () 15 separate models like the REMAX's model and from that we will 16 get the detailed behavior, so we are not really trying to 17 make -- 18 CHAIRMAN WALLIS: This goes a bit to Dr. Powers' 19 question that you have a code that will give you some 20 overall prediction of the whole behavior but when you 21 actually want to look at PTS you need another code. 22 MR. ELTAWILA: We don't disagree with that 23 statement. 24 CHAIRMAN WALLIS: No? Don't you need another code 25 for the details of the stratification and plume and all ANN RILEY & ASSOCIATES, LTD. (L. . Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 t a
a I i K 134 1 that?
' ,h 2 MR.'ELTAWILA: I agree with you. - Q,'
3 CHAIRMAN WALLIS: So you need another code? 4 MR. ELTAWILA: We cannot say that system codes are 5 going to be the cure for all things that NRC is dealing 6 with. 7 What I think the consolidation effort is focusing 8 on system codes and try to reduce the number of system codes 9- that they are all doing the same thing over all system 10 behavior, pressure and temperature, in the primary and 11 secondary systems. I 12 CHAIRMAN WALLIS: I guess that the point is that I ( 13 the specifications then for the system code are different i 14 from the specifications you might have for a PTS code? l () 15 MR. ELTAWILA: We don't have a PTS code, we have a 16 code called REMAX. It is some group of correlations based
.17 on experimental data that is correlated together that we are 18 going to use it for that purpose, so we cannot call it a 19 code per se that.we are spending a lot of money on it for 20 maintaining and developing it, so it is just a simple tool 1
21 that we have. 22 DR. POWERS: It seems to me that you have to I I 23 distinguish your thinking between the jobs the various 24 organizations are doing. You have line organizations that I 25 are working on the licensing issue in the context of rules l D\_ / ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 i Washington, D.C. 20036 (202) 842-0034 9
E k" i 2 135 1 and regulations. You have technical issues that come up 2 that Research works on to decide if, gee, mayba rules don't (G) 3 exist that should exist, maybe rules exist that are not 4 technically well-founded, a variety of different questions, ) 5 and yes, they might have two different tools and in fact I 6 would be distressed if Research came in and said, hey, for 7 our work we want "a" code -- because you don't know what 8 jobs you are going to-have to do. 9 The line organizations wants "a" code because they 10 damn well better know what jobs they are doing. 11 MR. ELTAWILA: We never made that statement and I 12 hope that when we talk about consolidation we are only 13 talking about the similar codes intended to assess the
.14 overall behavior of the reactor system, but we will always
\
( ) 15 need some special tools like CFD code in certain 16 application, the REMAX code, which is a group of 17 correlations that -- you know, to use it for assessing the 18 specific purpose application. 19 DR. POWERS: I'd like to go into this facilities 20 have served their purpose and what-not a little bit. 21 I know a couple of things that motivated the 22 statement. One was we said, gee, there will be a tendency 23 to preserve a capability that is becoming out of date and 24 you will. invent things to do for it and they will probably 25 be very useful things, but the fact is that those things h/ s ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 z 1. I
m q t 136 1 would probably be better done by some new dedicated facility A ( j 2 that may well be part of an international consortium, but 3 the preservation of a facility that is not quite right but 4 exists will be there as long as these facilities are there. 5 But you have come in and said, no, you found a 6 specific use that this is very good for and in fact the 7 instrumentation is not out of date. Is that the case? 8 MR. ELTAWILA: The instrumentation in this 9 facility or in the other facilities? 10 DR. POWERS: In whatever facility you are 11 preserving here. 12 MR. ELTAWILA: Well, for example, in the APEX 13 facility we have to make a lot of modifications to address 14 PTS. We have for example a loop seal on each of the cold () 15 legs that did not exist in the original facility. We had to 16 add instrumentation below the downcomer to be able to ; 1 17 measure the axle temperature distribution and the 18 thermocouple circumferentially too to look how the plume 19 will spread, so all of these, yes, we continue to modify the j l 20 facility to suit the purpose that we are using it for. I 21 The minute we finish with getting enough 22 information from this facility, let's say that the only 23 purpose for keeping _the APEX facility after the PTS issue, 24 we will have no other issue, I think I would be having a 25 hard time convincing my management and go through the I~[ k/ ANN RILEY & ASSOCIATES, LTD. Court Reporters j 1025 Connecticut Avenue, NW, Suite 1014 : Washington, D.C. 20036 l (202) 842-0034 j i
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137 ; 1 prioritization process to keep that facility.
# )- 2 It would be a decision made by somebody else.
3 Whether we want really to abandon that facility or not I 4 don't know what is the cost of the facility. Larry might 5 help us. It costs a lot of money and the decision to abandon 6 the facility has to be made a'well-informed decision at the 7 ' highest level in the agency here because we don't know what 8 the need is going to be, so I see that we have a role for 9- 'these two facilities for the next year. Beyond that I think 10 we have been working with the Department of Energy -- both 11 facilities got a grant from the Neery Program and so that at 12 least will help us reduce our expenses for these facilities. 13 DR. POWERS: It sounde to me that your opinion on 14 the facilities is not different from the ACRS's then? ( 15 MR. ELTAWILA: No , I think once we finish the # 16 facility's mission that we'll definitely have to assess the 17 need for this facility and based on all other factors that I 18 -discussed earlier. 19 With regard to the PUMA facility, we feel that the 20 facility can be used to study the coupled effect of the 21 thermal-hydraulics in the reactor system and the 22 containment, and in the quotation is something from the same 23 report,-that the ACRS indicated that the scope of the 24 thermal-hydraulic research program needs to be expanded, 25 coupling of thermal-hydraulics of the reactor coolant system ANN RILEY & ASSOCIATES, LTD. 3 - Court Reporters 1025 Connecticut Avenue, NW, Suite 1014
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138 1 to the thermal-hydraulics of.the reactor containment remain
/'~
(T) 2 a difficulty. 3 That is one of the reasons why we said we are 4 going to try to get as much information from this facility 5 right now before we make a final decision, to try to get all 6 this information so when we have a containment coupled to 7 the reactor system at least we will have the data to assess 8 this model, so that is the rationale. 9 Actually you provide us with the rationale in your , I 10 own letter, j 11 [ Laughter.] 12 DR. POWERS: Always happy to serve, 13 CHAIRMAN WALLIS: Two years ago -- this is the 14 year before the last. 15 MR. ELTAWILA: Well, last year the PUMA facility 16 had some difficulties because of the vessel itself. It has , 17 some cracks because of the type of steel that they have 18 used, so we really have not produced any data, so most of 19 the work -- we did not do much work at the facility last 20 year so we are starting studying this phenomena. We are l l 21 going to run tests next fiscal year. 22 The other things about the PUMA facility in 23 addition to the coupled containment and primary system, that 24 it can be used in a separate effects fashion. I think we 25 know that we need information about natural circulation in [ ANN RILEY & ASSOCIATES, LTD.
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l l 139 1 the vessel. The facility is suited to do that. We know that /D 2 break flow remains to be a problem for the codes and we want V 3 to get some information, so we can use it in a separate 4 effects mode in addition to the integral mode too. 5 So you are right. That was two years ago, the ! 6 statement, but we ran into a problem with the facility 7 itself. l 8 CHAIRMAN WALLIS: Is this whole code assessment l l 9 going to be based on past data? l 10 We have new codes coming along to be assessed. l 11 You do not yet have a procedure for assessing them, but is 12 the expectation that they will only be assessed against past 13 data that now exists? l 14 MR. ELTAWILA: I do not know what you mean about a ) ((~,)j
\
15 procedure for assessing the codes. 16 CHAIRMAN WALLIS: Is there a good enough database 17 when a vendor comes in with a code for NRR or whoever it is l 18 to make a decision, that it is a good enough code? Do they 19 have a good enough basis in existing data or do you see a 20 need to run these facilities to see if these codes can l
- 21. predict something? )
22 MR. ELTAWILA: As far as the assessment of the , 23 codes,-I can say that there are enough data to address 24 current generation of plants, although we might have 25 weakness here or there, because either the data is not [~D ANN RILEY & ASSOCIATES, LTD. (_ l Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 t
!~ { 140 1 available to NRC because it was generated in the BTSY 2 facility that we don't have access to the data or something 3 like that. 4 CHAIRMAN WALLIS: Is this based on someone 5 actually investigating these things or is this just your 6 confidence?
]
7 MR. ELTAWILA: No. This is based on -- I can send 8 you a copy of a report prepared by CSNI, which the NRC is a
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9 member of that group that developed a code assessment 10 matrices which will indicate what are the type of the 11 experiment,'looks at every model that needs to be assessed 12 and from that developed the identify the experimental 13 fncility that provides the data and whether it is separate 14 effect or integral effect test, and we are using the CSNI O id 15 report to try to get the assessment to the levels that have 16 been specified or recommended by the international 17 community. 18 If you look at that assessment method, you will 19 find information that is proprietary to some countries and l 20 we don't have access to them. l 21 CHAIRMAN WALLIS: So the agency overwhelms me with j 22 its confidence that it knows enough to assess all future 23 needs of the codes. 24 MR. ELTAWILA: No , I need to finish my -- 25 CHAIRMAN WALLIS: Well, I mean you never know, O ANN RILEY & ASSOCIATES, LTD. U- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i:
i i 141 1 something may come up where you have to assess something () 2 3-new, and you may need an experiment. MR. ELTAWILA: Okay. Let me continue with my 4 answer that that was for as far as operating plan, the CSNI 5 matrices covers only operating plant, it does not cover any
- 6. of the advanced reactor, because the United States has the 7 only ore has an AOWR.
8 CHAIRMAN WALLIS: You still impressed me with your 9 confidence that everything that you are ever going to need 10 abo:it -- to examine about existing plants has already been 11 studied adequately. 12 MR. ELTAWILA: Well, my confidence is coming from 13 my poorness or my inability to do what we want to do. So 14 that is not really a confidence, but it is a reality check (/ 15 to say that that is all what we can do, so that is we can -- 16 we will do it with what we have. If you feel that we are l 17 not doing enough, I think that we would like your comments ; i 18 on that, and the Commission will add your comments. 19 DR. POWERS: I think the thinking a lot in i 20 formulating the thoughts on thermal-hydraulics, at least my
.21 own thinking, was that we really were not in a position to 22 have an experimental facility kept active on the off chance 23 that something would come up in the future, that -- with the 24 existing plants, speaking strictly of existing plants. That 25 if something did arise in the future, that you really would l
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I l 142 1 want to have a facility that was suited for that. 2 Now, maybe you could go borrow one from some 3 international consortium or maybe you would have one of ; 4 these still operating that you could modify, but that 5 wouldn't be the basis for keeping a facility around, on the 6 off chance that something would come up. 7 MR. ELTAWILA: This will be something we will 8 provide the Commission. If the decision is made that we 9 don't have enough resources or we cannot keep that facility 10 for the off chance that something will happen in the future 11 that we need the facility, we will provide the Commission 12 with all the information, the cost of building this l 13 facility, the delay time, and the need for them, and I think 14 the Commission will make that decision. It is their i 15 decision, they are the one who authorized these things, and 16 we will give them this technical information, our judgment 17 and we will see what is their reaction to it. 18 DR. POWERS: That's right. And you have to 19 include in that the fact that -- I mean, clearly, as one of 20 our esteemed Thermal-Hydraulics members pointed out, it is ! 21 nearly always cheaper to modify an existing facility than it 22 is to build a'new one. And someone else pointed out to him, l 23 yes, but.a new one may be more suited to the experiment, 24 being instrumented, better capable to get the information 25 you want. I mean you have to make that kind of trade-off as ANN RILEY & ASSOCIATES, LTD. 4 Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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E 143 1 well as just the dollar trade-off. [ 2 MR. ELTAWILA: That's right. Well, now that you 3 mentioned the international facility, I would like to just 4 bring to your attention -- 5 CHAIRMAN WALLIS: But, seriously, the thing about 6 this, there is question of timeliness. If some new question 7 comes up which surprises everybody and turns out to be 8 important, if you have a facility, you might be able to do 9 tests. 10 MR. ELTAWILA: Absolutely. 11 CHAIRMAN WALLIS: If you do not have a facility, 12 you have to build it. Therefore, there is a delay time 13 which might be very important, not just money. 14 DR. POWERS: I think the counter to that is, how 15 many thermal-hydraulics issues have come up that had to be 16 solved within -- 17 CHAIRMAN WALLIS: That is all part of the evidence ) 18 that needs to be looked at. That's right. 19- MR. ELTAWILA: Well, if you look at the 20 international facilities right now, there are none except 21 the ROSA facility, and I don't know if the Japanese are I 22 planning to keep it for the long-term. But Vessey, a 23 decision, the other test facility, that larger scale is the 24 Vessey facility in France, and January of 2000 the facility 25 is going to be shutdown. (* ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 i Washington, D.C. 20036 (202) 842-0034 4
n I b 144 1 I might add that the issue of test facility in the n 2 thermal-hydraulics and in severe accident have been studied () 3 extensively by CSNI, and there is a group, NRC is a member 1 4 of that group, looking at these facilitie.s and trying to 5 identify if there will be a mission for this facility for 6 international cooperation rather than closing all of them at - 7 once exactly for the same reason that you indicated, that 8 there will always be an issue that will require testing, but 9 since we can't forecast when it is going to happen, it is , 10 very difficult to justify the budget. But if we can get 11 international interest in such a facility, I think that 12 makes our decision easier and the Commission rii.ght be 13 willing to support such a facility. 14 CHAIRMAN WALLIS: What does industry think? I
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(_) 15 mean does industry think it would be useful to have a 16 facility? 17 MR. ELTAWILA: Larry is about the closest one that ; 18 came from industry, so I will.-- 19 CHAIRMAN WALLIS: No. I mean -- 20 MR. ELTAWILA: You are asking me? 21 CHAIRMAN WALLIS: No, I think it would be useful 22 to have input from the industry about Shether they think it 1 23 would be.useful as sort of a national investment which they 24 might support to have a facility. 25 MR. ELTAWILA: I am going to tell you what NEI ANN RILEY & ASSOCIATES, LTD. (s Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l
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" I h i 145 1 position is, and that represents the industry, that we don't
() 2 need research and we should cut research completely. So 3 that is an industry position. That has been declared by 4 NEI. And we are working against this kind of -- 5 CHAIRMAN WALLIS: So they see no risk in this 6 approach / 7 MR. ELTAWILA: They don't see a reason for 8 anything that we are doing in the agency. I can even 9 extrapolate to the rest of the agency. They say that we are 10 over-staffed and we are not doing anything that benefits the 11 industry. So if you want to consider NEI views as 12 representative of the industry, you have it. 13 Larry, do you want to add something? 14 MR. HOCHREITER: Larry Hochreiter, now Penn State, [(,j\ 15 even though I have got a blue shirt on. I think industry is 16 interested in research that can be done that can help them. 17 We have, as you will hear tomorrow, we are building a rod 18 bundle experiment to look in much more detail at reflood 19 heat transfer, because this is where a large uncertainty in 20 the computer codes are. 21 We had a meeting with industry here at the NRC and 22 we had representatives from all the vendors, and all the 23 vendors supported the program. In fact, we have been 24 contacted by one of the vendors and they want us to run 25 specific tests for them for their geometries. O ANN RILEY & ASSOCIATES, LTD.
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i 146 1 One of the things that is occurring in the () 2 3 industry is the drive to increase the amount of thermal margin in the cores. We are going to higher and higher 4 power density cores, and the way they do that is they do 5 that by using better, improved grid designs, with mixing 6 main grids, with internal mixing grids that Siemens has and 7 so forth. And this allows you to get higher and higher 8 allowable critical heat flux limits. 9 -Well, these grids have the same effect during a 10 LOCA, they promote heat transfer, and we have some data that 11 shows that from other experiments. But no one has ever 12 designed an experiment with that in mind, okay. We have 13 always been after just cladding temperature. So there are 14 very few models, even in the best estimate codes, that can ("%
- 3. j - 15 represent the spatial grids. And this is an area that I 16 would think industry would be very, very interested in, 17 because it is going to allow them lower PCTs for the same or 18 higher kilowatts per volt.
19 DR. POWERS: Well, similarly, the PTS stufI ., 20 going to -- presumably, the PTS will allow people to start 21 up and shut down reactors with margins that are humanly 22 possible to track. 23 MR. HOCHREITER: Well, that is when you get your 24 worst. power shifts is at that point. That is when you need 25 the largest LOCA margins. ANN RILEY & ASSOCIATES, LTD. [~)' Nms Court. Reporters 1025 Connecticut Avenue, NW, Suite 1014 i Washington, D.C. 20036 i (202) 842-0034 s- i
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- 1 MR. ELTAWILA: The next bullet on page 5 is my own
() i ~~ 2 3 views, although there are some people in the Office of Research that support that. I really believe that we owe it 4 to the -- I am not going to use the word " owe it." I think 5 training future engineers is an essential part of the 6 infrastructure to keep this nuclear power plant operating. 7 And if we are going to train all these engineers only on 8 RELAP-5 and TRAC code, God, help us, you know, because that 9 is going to be a disaster. You need to get these people to 10 understand or see some behavior, look at how 11 instrumentation, how systems interact with each other, and 12 they are not going to learn that from the code. ! 13 So I really think that by focusing most of the 14 thermal-hydraulic research, separate effect and integral ('O
,j 15 effect test at universities, we are providing for the future 16 generation of engineers to be trained and trained correctly, 17 and these are the ones that they are going to be running 18 these nuclear power plants in the future.
19 DR. POWERS: It seems like a potent argument, that 20 the danger he is speaking of is that if everything you learn 21' about thermal-hydraulics comes from the computer codes like 22 RETRAN, then you don't have the experience of seeing a real 23 system, and it would be a fairly complicated system, or you 24 wouldn't be doing.the experiments on it, and how things 25 interact with each other, you don't have any way to (~'T ANN RILEY & ASSOCIATES, LTD.
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1 [ l ! 148 l l 1 calibrate these computer codes in your mind. ' () 2 3 MR. ELTAWILA: That's correct. You just would take the result of the computer code, apply them blindly and 4 don't use your judgment. I say I have seen that behavior 5 different here, one experiment or, you know, something like 6 that, you know. 7 DR. POWERS: Trust me, the most seductive thing 8 about computer codes, pretty soon you actually believe the l l 9 results coming out, and when they disagree with the j 1 10 experiment, you know there has to be something wrong with 11 the experiment. I mean it happens to you, and I don't care 12 you come into developing codes, once you have developed one, 13 you believe its output. ) 14 CHAIRMAN WALLIS: Well, there is an even worse /~'N (_) 15 thing, though, not only.is it a question of believing, it is 16 a question of selective before, you only believe what is in 17 the regulations. 18 MR. ELTAWILA: That's correct. The other comments 19 that the ACRS made I did not -- italic, these bullets here. 20 That more specific justification of new experiment and 21 expected payoff from their. result is needed. We agree with 22 you on that. And, particularly, you asked, how they 23' complement past results and improve the quality of the 24 specific capability in the thermal-hydraulic code. So we 25 are going to -- later on in the discussion, I am going to () (_ /- ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
149 1 give you some information on each facility that we have and (n) -2 Professor Hochreiter will be presenting some specifics on 3 the rod bundle heat transfer. 4 The next comment is that the ACRS has perceived 5 the need for best estimate code review and validation as 6 being insufficiently appreciated and even discouraged by the 1 7 NRC management. The eventual check is a thorough, time- l l 8 consuming investigation by the ACRS, far too late in the j 9 process to ensure efficient use of agency resources. 10 I just wanted -- this comment is made in the 11 research part of your report, but, as you know, the Office 12 of Research does not review vendor codes or EPRI code, and 13 your remark was related to that. So that is for your 14 information, that the review was done by NRR and not by /' (,,) 15 Research. And we have issued several memos about the 16 process for reviewing and validating the codes. Some of 17 them, one memo in particular, or letter from Bill Travers,
)
18 our EDO, to Dana Powers, and explicitly said that we are I 19 going to use the CSAU methodology. And in a couple of l 20 letters, a memo I sent to Jared Wermiel, one of them 21 forwarding the Reg. Guide that we prepared, and you aware of '
- 22. that Reg. Guide about code assessment and validation, we 23 adopted the CSAU methodology, and the other memo which 24 forward the evaluation done by the Office of Research, we 25 expressly stated that the CSAU methodology steps have not (O
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.1 .been followed, or at least violated by the RETRAN code 2 submittal itself.
3 DR. KRESS: They are going to use this slide 4 somewhat else. The word "through" is not right. It is 5 probably " thorough." 6 MR. ELTAWILA: Okay. 7 DR. KRESS: Just in case you were going to use it 8 somewhere else. 9 MR. ELTAWILA: Yeah, I think -- okay, I will check 10 that, " thorough." 11 DR. POWERS: Well, on the other hand, I think it 12 is also true that the -- 13 MR. ELTAWILA: No, it is "through time." 14 DR. POWERS: Is through a time.
) 15 DR. KRESS: It could be "is through a" 16 - MR. ELTAWILA: "Through a time."
17 DR. KRESS: Yeah, that could possibly be, but I 18 think it was " thorough." 19 CHAIRMAN WALLIS: No , I think it is " thorough." I 20 think " thorough" is the quotation that we have been pointing 21- out. 22 MR. ELTAWILA: Okay, I will try to quote it 23 correctly'next time. 24' DR. POWERS: I think the concern was not directed 25 at the RES management. I ANN RILEY & ASSOCIATES, LTD. \~ ! Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 g
i 151 1 DR. KRESS: No. () 2 DR. POWERS: I think it was directly more at the 3 EDO. 4 DR. KRESS: Yes. 5 DR. POWERS: We may not have been absolutely 6 crystalline clear who we were directing our comment to. 7 DR. KRESS: That's true. 8 DR. POWERS: I am sure it was not to the RES 9 management. 10 DR. KRESS: Yes. 11 DR. POWERS: But I think, nevertheless, that we 12 still think that -- I myself think that people do not 13 appreciate how difficult it is to review a code, how 14 difficult it is to do peer review, and how difficult it is () 15 to do code validation and verification. 16 MR. ELTAWILA: It is a time-consuming process and 17 I feel for my colleagues in NRR because they are under a lot i 18 of pressure to do that review in a very short period of 19 time. And if the ACRS can help in that, I think -- I will 20 let them speak for themselves, but I think it is an issue 21 that is important. 22 CHAIRMAN WALLIS: The final statement here was 23 tell you guys, not just you guys, but the whole agency, that : 24 it is really absurd for the ACRS to be the agent and 25 discoverer of errors. They should have been eliminated long O) i \/ ANN RILEY & ASSOCIATES, LTD.
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152 1 before anything comes near the ACRS. () 2 3 MR. ELTAWILA: I understand. In the next three viewgraphs, I am going to address specific comments that 4 came from Professor Wallis in particular on the package that 5 we sent you before the meeting. And I guess the first 6 comment Professor Wallis has, what is your definition of 7 best estimate analysis code? Do you know when you see one 8 or something like that? 9 And I think we know what is the definition of best 10 estimate analysis code. Reg. Guide 1.157 provides a 11 definition. It says that it should be free from deliberate 12 conservatism. It should contain sufficiently detailed model 13 to describe the relevant processes during a postulated 14 event. It should be sufficiently verified against 15 experimental data from differently scaled test facilities, 16 and should be capable to quantify uncertainty. 17 MR. ELTAWILA: In my discussion and Jennifer's 18 discussion that's what we are striving to achieve in our 19 consoli/atfon effort. We are going to get there, you know, 20 slowly bet surely we are going to get there, and that's what 21 we will have in the future. 22 CHAInfiAN WALLIS: I think the second bullet it's a l 23 bit difficult to know what is "sufficiently detailed" and 24 what " describe" means and what " relevant" -- that's not a 25 simple thing to do, to decide what those words mean. I ANN RILEY & ASSOCIATES, LTD.
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b ! k i 153 1 MR. ELTAWILA: No, I think we know nowadays that (~) v 2 through the PIRT process you will be able to identify what l 3 are the important phenomena to meet the performance of a 4 code for a particular accident scenario. And if the l 5 phenomenon is important and has an important contribution to 6 the outcome, we want to be sure that this model is described 7 in the code -- is in the code, assessed within the range of l 8 applicability that is going to be useful both against l 9 separate effect and integral effect experiments. ; I 10 I think it is -- although it looks like a ' 11 statement without any prescription, but we have been 12 employing it in the PIRT process and identifying the 13 important phenomena. j ( 14 CHAIRMAN WALLIS: PIRT comes early in the game. f~% 1 (j 15 Then when you have your code, you want to recognize that 16 when you see it, it's got to pass certain tests, and then 17 you're going to have to ask very carefully well, did it have 18 sufficient detail models and are they describing and so on. 19 You have to actually go through some kind of way of checking 20 off whether or not it does all these things. That's not a 21 trivial exercise at all. 22 MR. ELTAWILA: Well, it's not a trivial, and if 23 you recall during the AP600, so we have the experience, we 24 have done it. Through the AP600, we went through the 25 painful process, identify all the phenomena, and for these [] A/ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
4 b 154 1 phenomena that we are not able to say that they are in the 2 Code or the data base sufficient to adequately address them, [V) 3_ we relied on experimental data on scaling analysis and 4 expert elicitation to shed light on the issue. So it is not 5- really an issue of code per se but, you know, when you make 6 a measure, regulatory decision, you have to employ all the 7 information that you have available to you and to make that 8 decision. 9 With regard -- the other question that was asked, 10 a thermal-hydraulic code can be used for aging plants, and 11 the answer to that, yes, current code can be used. I'm not 12 saying that they cannot be used. They can be used as long 13 as you know the deficiency and the limitation of these 14 codes. When you get into a licensing renewal and some of /' ( s) 15 the important issues that are facing the Agency right now, 16 some of the conservatism in these. codes might not be 17 appropriate. They might unnecessarily lead us to a 18 conservative or penalizing regulatory decision. 19 So, yes, we can use them, but we know that they 20 have deficiencies and they will have limitation in the 21 mission of the Agency. 22 So if you look at some of the issues that are 23 affecting aging plants like irradiation embrittlement, l 24 stress corrosion, environmental qualification, we can -- you l 25 need the pressure and temperature load used to assess the I l [D, ANN RILEY & ASSOCIATES, LTD. As/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 ; Washington, D.C. 20036 ' (202) 842-0034 l
i, 155 1 capability of.the different components for these phenomena. () 2 We can use the existing code. We might get a conservative 3 answer. That conservative answer, if it is suitable, that's 4 fine, but for the future I don't think we'll be able to l 5- employ conservatism arbitrarily because in the area of risk-l 6- informed regulation we have to do something different from l 7 what we have been traditionally doing. 8 CHAIRMAN WALLIS: So risk-informed'is sort of the j 1 9 key. lever here for getting in a better code? Do you need a l 10 better code primarily because of risk estimation? 11 MR. ELTAWILA: That's correct. If you look at 12 even in 1996 before it was in vogue, the risk-informed 13 decision making,.that was one of the contributing factors to 14 develop the thermal-hydraulic research plan and we were () 15 looking into that in the 1995, 1996 time frame. So yes, the 16 answer is yes. 17 I think you asked me a question -- 18 CHAIRMAN WALLIS: But these are sort of general 19 assertions. .It would be more convincing if you could show j i 20- how there's some specific issue that faces aging plants. j 21 MR. ELTAWILA: I think I am going to come to that. I 22 CHAIRMAN WALLIS: How some current code 23- specifically in its predictions is unable to answer the 24 questions that you have. And I haven't seen -- I've heard 25 these general statements, but I haven't seen an example I p)- ( ANN RILEY & ASSOCIATES, LTD. i
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Il I 156 1 where comeone has shown that. gee, we can't do that with the (n) 2 present codes. I haven't seen anything so specific. It 3 would be good if you had some examples like that, where this 4 is what you'd like to be able to do.
.5 MR. ELTAWILA: Well, I gave --
6 CHAIRMAN WALLIS: This is -- 7- MR. ELTAWILA: How about if you wait until this 8 bullet here, the answer might be in the next one. 9 CHAIRMAN WALLIS: It might be in the next one. 10 Okay. 11 DR. KRESS: One good example would be'the steam 12 . generator tube rupture problem. 13 MR. ELTAWILA: As a matter of fact it's here. 14 DR. KRESS: Oh, it's on there? . r~)
'\,,) 15 DR. POWERS: Having looked ahead, I think these 16 are great examples.
17 MR. ELTAWILA: These are three examples here. 18 DR. POWERS: EG there. Except I would have put 19 them on the first slide, and I would have put the exact 20 regulations that you're speaking of here. The PTS has the 21- thermal shock and it's a specific regulation, boron dilution 22 is the ATWS rule, steam generator integrity is the GDC. And 23 I think in talking especially to the Commission about the 24 needs for this work, I don't think they understand that PTS 25 .is not some hypothetical thing that somebody dreamed up, it [)
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- 1. is a specific requirement, and it is a specific thing that
() 2 will plague this industry if we don't change that reg guide. 3 CHAIRMAN WALLIS: That's what you need to do. 4 MR. ELTAWILA: Well, we give you the examples. 5 But -- 6 CHAIRMAN WALLIS: We have to make the connection 7 in a way that my colleague didn't. 8 MR. ELTAWILA: No, I agree. 9 CHAIRMAN WALLIS: I think you need to do it that 10 way. If you're talking to the Commission, that's the way 11 you'd have to do it. You'd have to work down from their 12 concerns --
-13 MR. ELTAWILA: Actually I don't get a chance to 14 talk to the Commission. I'm not that high enough, you 15 know --
'16 (Laughter. ]
17 CHAIRMAN WALLIS: That's too bad. Maybe we can 18 change that. Maybe we can change that. 19 DR. POWERS: We'll work on that, Farouk. 20 I mean, I think this is a slide that nobody 21 understands. You know, when they go through and they start 22 cutting the research and say well, thermal-hydraulics we can 23 wait another year on, so we'll slow Farouk down a little 24 bit, I don't think they understand that they're not messing 25 around with.a bunch of guys playing in a sandbox studying [/\ A-ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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u 0 li 158 1 bubbles flowing through a pipe. They are messing around r~s
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(J - 2 with.their own regulations and their ability to respond to 3 licensees who are going to come forward with something 4 that's very, very challenging for the industry right now. i 5 MR. ELTAWILA: Well, if you recall the issue of 6 electrosleeve, I think this issue challenged the Commission 7 capability to deal with that issue. We were not able to run 8 an analysis in a timely fashion to support NRR. They needed l 9: a lot of analysis. We were able to provide them two or 10 three' analyses. We had the models that simplified a 11 phenomenon in the lower plenum of the steam generators, 12- complex phenomena, 3-D phenomena. We arbitrarily made some 13 assumptions, j l 14 So there are complex issues that force the Agency j
) 15 to take conservative positions, and the industry will 16 continue to complain about the conservatism that the Agency 17 is applying to them.
18 DR. POWERS: I would just love to see a couple of 19 viewgraphs on exactly that. I mean, I would want to carry 20 those with me. Because I think that people don't understand 21 that sort of thing. As a non-thermal-hydraulicist -- 22- CHAIRMAN WALLIS: Maybe we can put it in our 23 report. 24 DR. POWERS: I think we ought to have that in the 25 report. I think we ought to tell them here is something O ANN RILEY & ASSOCIATES, LTD.
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i 1 I i . 159 1 that should have been able to handle as a routine matter.
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i $ 2 They should have been able to handle electrosleeve when the , \_ / 3 issue came up. They should have been able to call Farouk 4 and say tell us what's going to happen with electrosleeve, 5 and he'd say get it for you the next weekend. And he can't. 6 MR. ELTAWILA: I can't. Let me give you an 7 example. We have our PRA people looking at the inside from 8 the IPE, and they found that all of the boiling water 9 reactors coming up with the number of valves necessary to 10 repressurize the primary system, it's all over the map. 11 Some of them say you can do it with two valves. Some of 12 them with 3 valves. Some say do we need the 8 valves. For 13 the same scenario. So they have no idea what's going on. 14 So they ask us for help. Guess what? We don't p) ( 15 have input decks for these plants to be able to help them. 16 Why?. The reason for that, because each input deck costs 17 $500,000 to develop. Why? Because the code is not good 18 enough to do it. You keep going into this circle. So - 19 CHAIRMAN WALLIS: That's what you should be doing, 20 though. You should be responding to those needs and finding 21 the tools to get the answers. 22 DR. POWERS: It seems to me that should be the 23 vision. 24 MR. ELTAWILA: But I tell you I will forward you 25 to user need letter and say it came from Research, not from I ANN RILEY'& ASSOCIATES, LTD. b Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 n n i
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ri 160 1 NRR. I,~ i 2 (Laughter.] V 3 Do you want the answer by October 15? Okay. Tell 4 me how can -- I even don't have input deck to give them an 5 answer.by October 15. The Commission is always faced with 6 these hard decisions. So the use, best judgment that they 7 have, and they make this decision, and they don't rely on 8 this code, so you don't see the visibility for these codes 9 because if I have to make use these codes, I will really 10 prefer to use any other tools available to me. 11 CHAIRMAN WALLIS: So they use engineering 12 judgment, j 13 MR. ELTAWILA: Yes. Engineering judgment means -- 14 CHAIRMAN WALLIS: But I think you should have a () 15 vision of what they ought to be using, and then you ought to i 16 make it happen. I 17 MR. ELTAWILA: We are telling you that, and we're 18 telling everybody the same thing, you know, so -- 19 DR. POWERS: But it's not coming across in this 20 analytic hierarchy process. If you've got real needs and 21 you've got a real vision that says look, I want to have a 22 thermohydraulic code with an input deck for overy single 23 plant in America, and I can run any problem that comes to 24 me -- 25 DR, KRESS: And get it to you within a week. O
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H i 4 0 l 161 1 CHAIRMAN WALLIS: Yes, that's what you need. 2 [v) That's what this Agency needs. 3 MR. CARUSO: Ralph Caruso from NRR. I just want 4 to let you know that NRR has been working on this problem 5 since 1992 to develop input decks for as many plants as 6 possible, and I believe.right now we have about maybe 20 7 decks or so. And what we did was we started with the decks 8 that were in the best shape, that were easiest and cheapest 9 to do, and we've run out of money. The decks that are left 10 are hard. There's no data available. You can't get the 11 data. If you can get the data, you have to go to the , 12 utilities, they have to be willing to provide you with all 13 the data for the plants. It costs a lot of money to do. 14 And there's just no will to do that.
/~T
(_) 15 DR. POWERS: Why shouldn't we at least let the 16 Commission see this is the vision, and if they say we don't 17 want to pay for that vision to make a conscious decision 18 rather than this dribbling along activity? 19 MR. CARUSO: Well, Farouk was right when he said, 20 you know, maintaining test facilities. You maintain test 21 ' facilities on the assumption that maybe sometime in the 22 future you'll need them, but the budget people say well, 23 what is it going to do this quarter, how is it going to i 24 help one of the pillars of regulatory success this quarter? 25 And the answer is spending a half a million dollars on a (' ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 h 2
~ i l 162 1 RELAP5 input deck for a plant that may never have anything j 2 go wrong, it's hard to justify that expenditure. 3 CHAIRMAN WALLIS: Well, at least you can know what I 4 it is you're turning down if you decide not to spend the 5 money. 6 MR. CARUSO: Well, that's true, and that's why 1 7 we've tried to do it as well as we -- 8 CHAIRMAN WALLIS: And then you can know that you l I 9 made that mistake when you find out you need it, because j 10 it's in the record. 11 MR. CARUSO: Well, sometimes people don't like 12 'to have those things'-- 13 [ Laughter.] 14 MR. ELTAWILA: Graham, you never dealt with budget () 15 people. I would like to invite you to the next budget i 16 ' meeting. 17 [ Laughter.] 18 The other things I would'-- I
-19 CHAIRMAN WALLIS: I suggest that you look at the 20 transcript of what happened in the last 20 minutes here, and 21 maybe you try to address that. These responses here you ,
1
- 22 have done in a couple of days, right? Because these are !
1 23 responses to suggestions I sent to you.
- 24. MR. ELTAWILA: Trust me, we've been saying that 25 for years until we are blue in the face. So don't think
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i; N < u 163 1 that we're not saying that. () 2 CHAIRMAN WALLIS: But maybe we need to see it, and 3 maybe we can point it out to the Commission. 4 DR. POWERS: I really think that translated into 5 some unregulatoryese and some into implications with 6 specific instances, and electrosleeve is a nice instance, 7 because that one really tied people in knots for a while. 8 MR. CARUSO: I'm just going to make the 9 observation with regard to electrosleeving that if you want 10 to do this -- I mean, you've got I don't know how many 11 different types of steam generators out there. They're all l 12 different, okay? The B&W plants, some are raised loop, some j 13 are lowered loop, they've got plugs in them. God only knows 14 where the plugs are. How do the plugs in whatever pattern () 15 affect the circulation patterns? Modeling stuff like that 16 .is a nightmare. l 17 CHAIRMAN WALLIS: So how are you going to make a 18 decision? How are you going to make a decision? 19 MR. CARUSO: That's the problem. That's the i 20 problem we face. l 21 CHAIRMAN WALLIS: Are you going to make it from 22 ignorance, or are you going to make it from knowledge? 23 MR. CARUSO: Well, what you have to do is you have 24 to be an engineer and make some simplifying assumptions -- 25 CHAIRMAN WALLIS: That's ignorance. That's ANN RILEY & ASSOCIATES, LTD. [! 's-Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 b;
L 164 1 ' ignorance. ( f 2 MR. CARUSO: The certainty just doesn't exist. 3 CHAIRMAN WALLIS: Yes, but -- 4 MR. CARUSO: The answer -- 5 DR. POWERS: I mean, I think he understands that 6 that's the situation now. We're looking -- because it's a 7 discussion of research, we're looking at -- when your son
'8 comes to work for the-Agency and takes your job, do you want 9 him to have the same kind of headaches that you have now?
10 MR. CARUSO: No. No. 11 DR. POWERS: That's what we're trying to solve. 12 MR. CARUSO: Well, we would like to have the tools 13 to develop -- and I'm going to support Farouk in this 14 effort -- develop to the extent that they're usable by a O) (, 15 much wider group of people. I've been saying this for a 16 while. You've got to have tools that are useful to the PRA 17 people. One of the reasons these codes aren't useful right 18 now is that they require -- there may be a handful of people 19 in this room that can run one of these codes, okay? And 20' these are all people in the Agency that can do it. And they 21 need to be almost simulator codes, where you can set up a 22 PRA analyst down in front of a computer screen and it will 23 run through the simulations with one, two, three, four, six, 24 eight ADS valves running. And it will give him a result 25 that he has faith in, and if he pushes the simulation beyond I') ANN RILEY & ASSOCIATES, LTD. \/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
l 165 1 what it's capable of, if you're going where you shouldn't ( 2
) go , go get some help in this area.
3 DR. POWERS: I think that's a beautiful vision 4 statement. 5 MR. CARUSO: That's the vision. That is the 6 vision. 1 7 DR. POWERS: But I haven't seen anybody write that 8 vision down, and I don't see the Commission saying ah, what , l 9 I'm affecting is this guy's vision. Now do I want to affect 10 that? How long do I want to delay this guy having this 11 vision? I mean, it seems to me that a perfectly legitimate I 12 vision -- 13 MR. ELTAWILA: I'm going to be controversial, 14 okay? And you had a perfect example this morning about how ( ,) 15 this Agency shoots itself in the foot. You have here GSI 16 23. You came with a resolution of the issue based on 17 probability alone. 18 No one addressed thermal-hydraulics. If that is 19 the way that the' agency wants to make the decision, let's 20 'save our money and let's put all these codes to bed and 21 nobody needs_them, you know. So I think the PRAP will have 22 the tendency to try to do a very simplified analysis of 23 reality. 24 CHAIRMAN WALLIS: Well, you guys have been too 25 jaded. I would like to pursue this vision a bit more. No
'[D \/
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I l i I 166 1 only do'I see -- I like the vision as it has been sort of 2 briefly sketched out here, I like the vision that when the [V) 3 agency makes a decision, a graduate student can pick up on ; 4 the Internet and get whatever the code is and can do some 5 stuff, and can satisfy herself that it makes sense. 6 MS. UHLE: Thanks. 7 [ Laughter.] 8 CHAIRMAN WALLIS: Then you will have public 9 confidence, when it is out there in the open, it is not 10 something which is done with engineering judgment in smoke-11 filled rooms and all that kind of stuff, it is actually 12 done. 13 MR. ELTAWILA: I would like to get into that, I 14 agree with you. () 15 CHAIRMAN WALLIS: It is out there clearly what was 16 done, why it was done, what was predicted and so on. 17 MR. ELTAWILA: Okay. 18 CHAIRMAN WALLIS: And somebody else can check it 19 out. 20 MR. ELTAWILA: All right. Before I forget that 21 point, I think Ralph is right that he develope' 611 the 22 input deck, but he forget that he sent me a meno saying you 23 modifying the codes so much, all the input decks that I have 24 developed are obsolete now. Right, Ralph? 25 MR. CARUSO: I made a point of that in our meeting [N ANN.RILEY & ASSOCIATES, LTD. \~s Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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j . 167 1 in Annapolis. I spent $300,000 for a deck. The next week a 2 great national laboratory changed the codes, so I just spent 3 another $30,000 to get it to work with the new version. 4 MR. ELTAWILA: Look at the reality of this 5 situation that we are in. That is really a difficult 6 situation, and because of the complexity of the codes, you 7 cannot modify this input deck very easily. And that is why 8 you will find the relationship to the GUI, why the GUI try 9 to make these things simpler in the future. 10 CHAIRMAN WALLIS: Well, it is not absurd to dream. 11 I can see graduate students, undergraduates sitting there in 12 the room, instead of playing some stupid game where they are 13 shooting with aliens with something, they can actually run a 14 LOCA analysis, and they would be much more interesting. 15 They can be the operators, they can do all kinds of stuff. 16 DR. POWERS: Well, I am less concerned about the 17 operators than I am the line organizations here. But having 18 the line organization guy, and I mean any of them, sit there l' and say, I wonder what a LOCA at Haddam Neck looks like with 2s a the following modifications to the plant. And he clicks it 21 up and he runs it, and just as it was said, as soon as he 22 pushes it beyond the limits, there is a little flag that 23 picks up and says we are going into the region we are still 24 working on or something like that. I think that is a 25 wonderful idea. O - ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 II
f l I I 168 1 All right. Maybe you never get there, but that i ( ) 2 seems like the thing to strive for. And that is the kind of 3 vision that I think the thermal-hydraulics program for 4 research should have. Deliver that capability to the agency 5 and these questions of coming in here -- 6 CHAIRMAN WALLIS: We will put it in our report, we , l 7 'will send it right up to the Commission and maybe they will 8 even read it, because they will understand it might be 9 useful. 10 MR ELTAWILA: I am not going to say a word, 11 but -- 12 MR. HOCHREITER: Larry Hochreiter. One of the 13 things that occurred on the AP600 review, which I think the 14 Commission should be very proud about, was that they ! ( '15 immediately started modeling a plant and start doing their 16 own calculations on the plant, independent of Westinghouse. 17 In fact, they did it so quick they actually got irritated i 18 when we would change the plant design. I 19 DR. POWERS: That seems to be a big irritation 20 around here. l 1 21 MR. CARUSO: A lot of our money. 22 MR. HOCHREITER: Yeah, it is not trivial. You 23 change a schedule on a piece of pipe, you change all the 24 flow areas, et cetera, et cetera. However, the point is 25 they had the capability of doing that and it no longer f) As ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 [
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! I 169 1 became a question of a vendor like Westinghouse convincing
() 2 3 people that the systems would work, it was more the degree of, well, how well they work. Okay. 4 Because the NRC could do its own independent 5 calculations, I think that helped the review tremendously, 6 and it is to their credit that they did. 7 CHAIRMAN WALLIS: I think it was crucial. 8 MR. HOCHREITER: I agree. 9 CHAIRMAN WALLIS: It amazes me that it took so 10 long to get there. 11 MR. HOCHREITER: Well, you and I were involved in 12 upperhead injection back in the '70s. 13 CHAIRMAN WALLIS: It is still going on, still 14 going on. () 15 MR. HOCHREITER: Well, and at that point the staff 16 had no calculational capability to model a plant with 17 upperhead injection, so they had to believe the Westinghouse 18 calculations. Well, Westinghouse barely believed them. 19 (Laughter.] 20 MR. BOEHNERT: He can say that now. 21 DR. POWERS: They are going to take his blue shirt 22 away. 23 CHAIRMAN WALLIS: They believed the ones which 24 gave the right results. 25 MR. HOCHREITER: Of course. That is a given. 1 O \> ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 ! (202) 842-0034 i
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i 170 I 1 That put the staff in a very disadvantaged position, and, l
T basically, what happened to Westinghouse is they continually (d
2 3 got ratcheted and ratcheted and ratcheted and ratcheted, 4 until the benefit of the new system almost disappeared on 5 plants. When we ran tests, we got a huge benefit. But I 6 think it has really led to the fact that the staff had no 7 way of doing an independent audit calculation, and I think 8 that is crucial. 9 CHAIRMAN WALLIS: Well, let's build on that 10 success and then take the next step. So what is it we could 11 do get even better? 32 MR. ELTAWILA: The other question that you asked 13 is, what is wrong with-the present method? And I think I am 14 going to cover that later, and Larry and Jennifer are going O) ( 15 to address this, so I am going to skip that one here. 16 How close are the RELAP5 and TRAC-P prediction for 17 various events? Just to give you a brief background, when 18 we originally developed these codes, our great vision that 19 we would benchmark these codes against each other to have 20 them double check, and so we don't bias our views by the 21 code developers. Unfortunately, even during the good old 22 days when we had money, we never did that. Every code just 23 went in its own direction and we never spent the time or the 24 effort to benchmark the codes against each other, and they 25 became -- each code organization developed code, carved a
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i I l 171 1 mission for the code. NRC went along with that. And what () 2 3 is why we have all these four codes right now. CHAIRMAN WALLIS: What concerns me, if you just 4 have one code and it is the Oracle, there is nothing to 5 check it. 6 MR. ELTAWILA: No, there are. There are. There 7 are. We are continuously participating in international 8 standard problem at CSNI. I don't know if I put that here. 9 CHAIRMAN WALLIS: So you have a challenge to the 10 French to protect the same thing with their codes. 11 MR. ELTAWILA: We actually work, yeah. So there 12 are the opportunities to work in the international community 13 in this regard. 14 CHAIRMAN WALLIS: Okay. So that is okay. So you () 15 are answering it that way, that's fine. What ordinarily 16 happens? 17 MR. ELTAWILA: Just for your information, as a 18 part of our PTS study, we did calculation using the RELAP5
- 19. and TRAC-B and they give completely different results. You 20 know, that is --
21 CHAIRMAN WALLIS: That is a concern then. If we 22 are consolidating codes, which ones are going to win? 23 MR. ELTAWILA: Well, I don't -- well, we will get 24 into the details of that I think as part of the 25 consolidation effort. The first phase of the consolidation,
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l i 172 , I we wanted to make the consolidation code as good as the
/x 1 2 existing codes right now.
(O And so this way we will be able 3 to eliminate the maintenance cost associated with the i 4 individual codes. 5 Then the second phase, which will start 6 immediately next fiscal year, is to look at the physical 7 model and try to compare that experimental data. And based j 8 on the comparison to the experimental data, the wide range , 9 of experimental data, we will make a decision on which model 10 that will be retained in the code. 11 You raise a question about minimizing user effect, i 12 and I think I really don't need to tell you that user effect 1 13 is one of the most prominent reason for differences in code 14 results, because if you look at a code like RELAP5 code that () 15 has a lot of options, so you give the code to five or six 16 people for the same experimental facility, you know, that we 17 have data, rnd you will get completely fix or six different l 18 results. 1 19 CHAIRMAN WALLIS: That is what the utilities 20 coaplain about. They get this thing, there are so many 21 options. They get all kinds of results, which one should 22 they believe? 23 MR. ELTAWILA: And that is what we will be try -- 24 so user effect is a very important factor. And we don't -- 25 and I am not advocating that we should regulate user, but I
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i i 173 1 think we should pay attention when we receive an analysis. () 2 We.want to know the person, what kind of nodalization 3 analysis he performed, what time step study he performed. 4 What is the basis for choosing -- 5 CHAIRMAN WALLIS: How do you know if it is good? 6 I mean you may know all the things that this user did. 7 MR. ELTAWILA: Well, that is what the user did, 8 and I think we -- 9 CHAIRMAN WALLIS: I used to have a random user -- 10 it tries all kinds of combinations. Il DR. POWERS: Monte Carlo user. 12 [ Laughter.] 13 CHAIRMAN WALLIS: But if you had a quick enough 14 code, you could do that. You could put it, you could have a () 15 . lot of different assumptions made by this computer who is 16 the user and see what difference it makes. 17 MR. ELTAWILA: No, we know what difference it 18 makes. 19 CHAIRMAN WALLIS: You do. 20 MR. ELTAWILA: We have seen it through CSNI 21 report. 22 CHAIRMAN WALLIS: It makes a difference, but how 23 are you going to -- 24 MR. ELTAWILA: It makes a huge difference. 25 CHAIRMAN WALLIS: How do you know what difference ~h ANN RILEY & ASSOCIATES, LTD.
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174 1 it will make with a specific question? You don't, you have (em) 2 .to try it. 3 MR. ELTAWILA: If you don't know, if you don't 4 have confidence in a code that can predict a very controlled l 5 experiment, what kind of confidence would you have when it 6 is predicting the overall performance of a plant? 7 CHAIRMAN WALLIS: Well, what kind of confidence do 8 we have? We have a code like RETRAN comes before us and it 9 shows a curve, right. This is supposed to represent some 10 transient. We don't know which assumptions were made by the 11 user. We don't know that if some other user did something 12 different, we would get a different wiggle. So how are we 13 supposed to evaluate? l 14 MR. ELTAWILA: You are supposed to evaluate based () 15 on sensitivity study. You have to provide a lot of 16 sensitivity studies, you look at the assessment of the code 17 against the experimental data, the uncertainty analysis that 18 they have done, and from that you can draw a conclusion. 19 Yeah, there is -- I am not on the edge of a cliff by 20 changing any of these important factors. 21 CHAIRMAN WALLIS: So one transient might involve, 22 say, a hundred different runs with different users. 23 MR. ELTAWILA: And that is what Ralph indicated, 24 that he wanted a fast running code to be able to do that, 25 because that is the only way you can reach confidence. '[~h
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i 175 1 Especially.in the future when we are saying that we are i 2 going to eliminate certain requirements because of burden 3 , reduction, you want the decision to be an informed decision, 4 not based on a single code calculation or what you call 5 engineering judgment. 6 CHAIRMAN WALLIS: Well, that is what I was looking 7 for in your specifications for the code that you want to 8 have, and you say you need a fast running code, you have got 9 to put in all these different user assumptions. Now, maybe 10 there are 20, maybe it is four by five, or something, 11 different assumptions you can put in which are reasonable, 12 into a code to predict one thing. So the computer code 13 doesn't just have to do one run, it has to do 20 runs. And 14 you want an answer in a reasonable time, you are going.to m 15 figure out how fast that code has got to run, it has got to 16 run very fast. 17 Now, you ought to put that in as a requirement of 18 the code. 19 MR. ELTAWILA: Okay. We will give you that. We 20 will give you -- 21 CHAIRMAN WALLIS: Don't just say it has got to be 22 faster, but it has got be, you have got 10 minutes to 23 predict a whole transient or something, so you can run a 24 lot. 25 MR. CARUSO: Actually, Dr. Wallis, the cheaper way I ( ANN RILEY & ASSOCIATES, LTD. Court Reporters i 1025 Connecticut Avenue, NW, Suite 1014 l Washington, D.C. 20036 (202) 842-0034 i
a i 176 1 to do is to just buy more computers.
/~ i 2 CHAIRMAN WALLIS: Okay. We will run them in O
3 parallel. We will have them all be different users and run 4 them in parallel. 5 MR. ELTAWILA: They have to run first, right. 6 MR. CARUSO: But actually it is cheaper to just 7 buy more computers. 8 MR. ELTAWILA: That's right. 9 CHAIRMAN WALLIS: Okay. Then that should be in 10 the vision, too, that, in future, NRR analysts will have 20 11 computers running in parallel. 12 MR. CARUSO: Actually, they do right now. 13 CHAIRMAN WALLIS: Okay. Good. We didn't know. 14 MR. CARUSO: They have them available to them. () 15 CHAIRMAN WALLIS: Oh, they are available. That's 16 different. 17 MR. CARUSO: No, no, what I mean is we have a 18 computer network with 20 computers on it that any user can 19 log on to. 20 CHAIRMAN WALLIS: So we give you a homework 21 problem to run a certain transient in a certain plant, you 22 can do all this? 23 MR. BOEHNERT: Ralph can start 20 jobs -- 24 CHAIRMAN WALLIS: And finish them in one day? 25 MR. CARUSO: And finish 20 jobs in one day, if (~' A ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 U
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i i 1 177 1 they run. ID 2 CHAIRMAN WALLIS: Okay. U 3 MR. ELTAWILA: I think Ralph is correct. ! 4 You indicated that vendors and utilities rarely 5 take CSAU seriously, and I think I might agree with you on I l 6 that. And the reason of that, that the staff never offered l 7 guidance on how to use the CSAU, and I think we are working 8 with NRR to develop that Reg. Guide and that will shed light 9 about what does the NRC anticipate in the area of grid 10 review so utility and vendor can use this information. 11 And the other things which is important, when the 12 methodology comes here, that we will have a competent staff 13 that will be able to-do the review in an efficient and a 14 timely fashion, and that will increase the use of the CSA'J l 15 methodology. 16 CHAIRMAN WALLIS: It is not just in the i 17 universities that you want to establish this competencia, you ; 18 want to have it here. 19 MR. ELTAWILA: Absolutely. The impact of budget 20 on the staff reduction. If you recall, in the research plan 21 that we asked the Commission for $6.6 million per year, and 22 we identified a number of staff. Never got that budget from 23 day one. So every year was less and we are now at $4 24 million and we are trying to do more, and we have been 25 requested to do more with less, so we are going to survive /~h ANN RILEY & ASSOCIATES, LTD. k ,) s Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 h I
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.l 178 1 this.
() 2 3 Farouk? CHAIRMAN WALLIS: Are we going to survive today, You have taken -- this is about a third of your 4 slides and you have taken -- if you extrapolate, you are 5 going to take all of -- 6 MR. ELTAWILA: I will tell you what, we are going 7 to keep you here until you finish with us. 8 _[ Laughter. ] 9 MR. ELTAWILA: Really, because more or less I ever 10 time I come here, you ask us questions that we cover this in 11 another meeting. We are going to go over it in painful 12 details until you give -- say " uncle," I am not going to ask 13 _you that question again. 14 DR. POWERS: Farouk, before you make promises your () 15 body can't keep up, I will point out that the last two 16 meetings I have kept these guys to the wee hours, and they 17 haven't complained a bit. 18 MR. ELTAWILA: I will try to go faster. I think 19 the result of the budget impact is written here. If you 20 want to write it in your report, you can read it. In j 21' addition to that, we lost some key staff, and we tried to 22 bring the work in-house, the equipment, some activities and i 23 you are looking at the whole staff of the Office of 24 Research, and she is sitting behind you. So that is, you 25 know, although that we might be able to hire a couple of ANN RILEY & ASSOCIATES, LTD. s- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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I 179 1 people in the next few months.
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'I i 2 DR. POWERS: Does this mean that she is in a heck V
'3 of a-signing bonus?
4' MS, UHLE: Yeah, right. 5 DR. POWERS: You can renegotiate, you can hold out 6 for training camp and see if you can't get a good signing 7 bonus, is that the status? 8 MR. ELTAWILA: The NRC strategic goal, it has four 9 arenas and under these-four arenas, they have performance 10 goals. The one that affects the thermal-hydraulic research 11 in particular is the nuclear reactor safety arena. And the 12 Commission stated, hopefully, they meant it, we will 13 maintain research capability to provide timely and 14 independent technical bases for NRC to carry out its () 15- regulatory program efficiently and effectively. 16 And the other arena is the international 17 involvement, and, as you know, our code, regardless of what 18 we say about them, are the most widely used code in the 19 world. So we want -- so I have contribution to the agency
'20 mission to try to keep the involvement into international 21 activity.
22 DR. POWERS: It seems to me that this first line 23 that Farouk has up on-this viewgraph is a great one for us l 24 to adopt in our research report and say --
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1 180
,1 have.
() 2~ 3 DR. POWERS: not doing it. No, no, no. Tell them that they are 4 DR. KRESS: And tell them why. 5 DR. POWERS: And here are the things that you are 6 not doing, -- 7 DR. KRESS: Absolutely. 8 DR. POWERS: -- that show you why you are not 9 doing this, and give them the advice, either live up to what 10 you are promising, or change the promise. One or the other. 11 I kind of like this, because I think you have given us some 12 heck of a good examples of where the " efficiently and 13 effectively" are not quite as efficient or as effective as 14 they could be. And the trend you are pointing out on your , r (_,h) 15 . budget slide is away from efficiently and effective. 16 CHAIRMAN WALLIS: Well, I mean you can redefine J 17 capability timely, technical basis efficiently and 18 ' effectively to sort of cover anything you are doing. I l 19 MR. ELTAWILA: But look at the performance goal 1 20 and that is how you can apply them to performance goal, 21 which specifically says maintain safety, and everybody knows 22 that increases public confidence. And public confidence, in 23 my opinion, as I wrote in my report, is that you cannot have 24 a public confidence if NRC, on the other hand, say that i l 25 there is no issue and you have the technical community say i [^\
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i l I , 181 1 there is an issue, or the ACRS and the staff disagree, or 2 consultant disagree about certain phenomena. (G~^) 3 I really think the public confidence -- the public 4 is not well informed in this area, and we have to carry that l 5 responsibility to be the advocate of the public. 4 6 The only way to do that is to be sure there is at 7 least in the scientific community agreement that what we are 8 doing is the right things. We have all the technica.1 bases 9 for the regulatory decision. l 10 CHAIRMAN WALLIS: If you look at effective, like ' 11 the first one my colleagues so love, it may be effectively 12 is you know it is effective when you have got the kind of 13 vision that we have talked about earlier. 14 Now what some people are satisfied as being () 15 effective others may not be. I would like you to be 16 ambitious about what is effective, not restrictive. Say to 17 be really effective, this is what we need to have -- the 18 budget restricts us to this, but that is where we would 19 really like to be. 20 MR. ELTAWILA: Maybe I will let other people j 21 address that, but you have to live within the constraints 22 that you have around you. I can't give a vision about it, 23 and I think I have to admit that Ralph Caruso was one of the 24 people that fought us at the beginning and said ask for more 25 and define better goals and things like that, but the (~ ANN RILEY & ASSOCIATES, LTD. ( _- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i
182 1 reality of the matter is your vision does not come to the 2 Commission. It goes through about 400 people in concurrence [J'l 3 and by the time it gets to the Commission your vision is not 4 your vision anymore. 5 It is collective vision and maybe one person's 6 vision at the end, so let's be realistic about, you know, 7 how we can change things around here. 8 DR. POWERS: I think Farouk has got a good point. 9 When you are in the swamp fighting the alligators, it is 10 hard to remember the idea was to drain the swamp and I think 11 we have-to and can legitimately -- 12 CHAIRMAN WALLIS: The idea is to get to the 13 Promised Land. 14 DR. POWERS: To use our research report as a way () E15 of communicating the visions. Because like he said, this is
.16 one part of the agency and ;* goes through lots of 17 filtration and things like that and different people wanting
.18 to know what is going on, and quite frankly, the Commission 19 hires us to give them insight on these technical, detailed 20 technical issues that they have some sense are important.
21 I don't think it is unfair to say all right, let's 22 let the research report communicate a vision of what 23 thermal-hydraulics at the NRC ought-to look like. 24 CHAIRMAN WALLIS: And the great thing about our 25 research report is it doesn't go through 12 different ANN RILEY & ASSOCIATES, LTD. O)
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183 1 channels of approval and -- although we have highly paid 2 editors. 3 DR. POWERS: The difficulty with our research 4 report is that it goes through 10 independent thinkers -- 5 DR. KRESS: -- none of whom will agree on 6 anything.
- 7. DR. POWERS: Can't even agree on the time of day 8 successfully.
9 MR. ELTAWILA: Okay. If you look at the four 10 performance goals, they are to maintain safety and increase 11 public confidence, you reduce unnecessary regulatory burden, 12 make NRC activities and decisions more effective, efficient 13 and realistic, and I think the paper and in the viewgraphs 14 here I tried to tie each one of our activities to the O Q 15 performance goal. 16 I would like just for this viewgraph -- 17 CHAIRMAN WALLIS: I have always been really 18 intrigued by the statements like more effective, efficient 19 and realistic. What really matters is how realistic does it 20 have to be -- the incremental making it a little bit more 21 realistic, you.really need to know how realistic it needs to 22 be to be good enough, and that has never been faced. It's 23 always been sort of presented as being an incremental 24 improvement. 25 No one has really sat down and said how effective O ANN RILEY & ASSOCIATES, LTD. (_/' Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 4
i ;T i i 184 1 do we need to be. It's always to make it more effective. r3 2: ( s It's a vague statement unless you have some way of trying to
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3 get'to it. 4 MR. ELTAWILA: No , I really, I think how effective 5 we want to be. Take, you know, the issue of the 6 electrosleeve. Do you think the agency ducision was the 7 right decision? Were we effective? 8 CHAIRMAN WALLIS: There ought to be some way of 9 measuring whetti- it was effective or not and what could be 10 done next time to do it better. 11 DR. POWERS: Well, certainly effective. Whether 12 it was efficient or not is open to question. 13 CHAIRMAN WALLIS: Everything we do is effective 14 because we define it, so it is sort of a circular thing. I () 15 don't see an external measure of how effective the agency 16 is. 17 DR. POWERS: I think it is much easier to know 18 when the agency has been ineffective than when it has been 19 effective. I think Larry pointed out an example of where it i 20- would be legitimate to say they weren't effective. 21 I think he equally pointed out an example of where i i 22 they were effective. 23 CHAIRMAN WALLIS: Or less ineffective. 24' DR. POWERS: So I think one would have to concede a l 25 not everything is equally quantified. It may not be i i [)
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185 l 1 worthwhile to spend an enormous amount on quantification. 2 MR. ELTAWILA: Let me go over this viewgraph 3 quickly, because that answers all the questions -- 4 [ Laughter.) 5 MR. ELTAWILA: If you want to know how we 6 are doing, why we are doing things and how we are doing it, 7 you can look at it this way. The Commission said that we 8 are going to -- the mission of the Commission is to protect 9 public health and safety and in doing that they set a lot of 10 criteria. 11 We have a lot of criteria to be able to achieve 12 that. They are to limit fission product release. In order 13 to do that, you limit fuel failure, you limit reactor j 14 coolant system breach, you limit containment breach, and i G Q 15 here the source of the information is listed here, whether 16 it is the regulation itself or Standard Review Plan, but we 17 translated these criteria here into a set of phenomena that 18 can be measurable, like peak clad temperature, like for 19 example cladding is strained, like reactor coolant system 20 and steam pressure and temperature, containment pressure and l 21 temperature, hydrogen. 22 These are the parameters that we build our 3 23 regulation on and for that, in order to do that because 24 there are a lot of variations of the scenario, you need to 25 have plant transient analysis tools to be able to predict l
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i 186 1 these parameters here or the speed limit, and in order to .n ( ,) - 2 have good analysis tools we have to have adequate data. 3 So why we have the codes is to be able to 4 calculate these to be able to meet this limit, to be able to 5 limit fission product, how we are going to maintain public 6 health and safety by following that, so that is in the 7 traditional approach here at the NRC for as long as I have 8 been here. 9 CHAIRMAN WALLIS: That is okay, but then you have 10 to follow through in great detail here. Suppose that you do 11 develop a better code. What is the payoff in the other 12 various boxes above it? 13 MR. ELTAWILA: Let me get back -- hopefully I am l 14 addressing that in the viewgraphs after that. O (,,/ 15 The next viewgraph is actually -- said. exactly 16 what I said, so I am not going to go over it, and I will 17 move to Viewgraph Number 14 -- what are the desired goals of 18 the code features, and that we had a meeting in 1996 -- and 19 one of the breakout sessions was a session about the feature 20 of the codes that need to be incorporated into any code in 21 the future. Ralph Caruso chaired that session and they came 22 up with a list of improvements here. 23 The double square here means that the activity is > 24 ongoing; the single square here means that it is going to be 25 completed -- started in Fiscal Year 2000; this symbol here, h ANN RILEY & ASSOCIATES, LTD. s- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
187 1 that we are in the first phase and we have some ways to go; I
) 2 and this arrow means that it's a long time, so they list 3 here the improvements that they want and by the 4 consolidation we feel that we are addressing quite a lot of 5 these.
6 They think there's going to be in the long term 7 the subchannel analysis capability and the coupling to fuel 8 codes and we have not done any work in this area. We 9 finished the 3-D reactor kinetics. We are finishing the 10 modern architecture. We hopefully are conserving the 11 investment in the input models by developing the GUI, so we 12 on our way to achieving some of the user requirements that 13 .came out of a user group that included NRR. 14 I don't know if I need to go through this ( ) 15 viewgraph here. You have seen it before but here are the 16 different objectives and here are the activities that we 17 have and we're trying to highlight from here how each of the
'18 ' activities is addressing the specific objective.
19 CHAIRMAN WALLIS: I have the same point I had
- 20. before -- more robust, run faster, more accurate -- how will 21 you know when it is fast enough and what is your measure of 22 robustness and things like that. All these things are going 23 to be better, but what are you aiming at and what is the j 24 = measure?
25 MR. ELTAWILA: Right now I am aiming for our O ANN RILEY & ASSOCIATES, LTD. (~/y Court Reporters 1025 Connecticut Avenue,-NW, Suite 1014 l Washington, D.C. 20036 i (202) 842-0034
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n- , 3 II a-188 1 experience in the AP600 and other users can you tell more ( ) 2 than what I can tell you. When I have a code that can't 3 progress through about five seconds in two days, that is not 4 acceptable. l 5 CHAIRMAN WALLIS: No. 6 MR. ELTAWILA: So I am having a very modest ; 7 expectation right now. My expectation is to get the code to 8 run without the user having to nurse it all the time. i 9 CHAIRMAN WALLIS: It seems to me that you are like 10- the' computer industry when they had everything on these i 11 mammoth computers in about four different places that ran 12 all day. Now we have mini-computers we can carry around 13 which became far more powerful. I would like you to have 14 the vision of the mini-computers that anybody can run and O (_ ,/ 15 they are thousands of times faster than they did in the , 1 16 past. ] l 17 MR. ELTAWILA: But the code is not amenable to run j 18 on these. It has reached the point that the time step l l 19 .becomes so small it brings it to a screeching halt and you I 20 cannot -- 21 CHAIRMAN WALLIS: That's probably the stiffness of 22 the equations and things like that. 23 MR. ELTAWILA: Well, we will try -- we are working 24 to improve these things. 25 DR. POWERS: I wonder what does it take to frue i ANN RILEY & ASSOCIATES, LTD. j
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E . I 189 1 .up, say, your time and maybe Ralph's time for, say, a i () 2 retreat or.some mechanism to sit down and say, gee, if I had 3 my dream of dreams, what would I mean by "run faster" -- you
-4 know -- where would I be satisfied?
5 A lot of things you may never be satisfied, like 6 more accurate. I suspect you are never satisfied, you 7 -always want a little more in there, but run faster there is 8 clearly a time when people quit complaining about the run 9 time in a code. 10 There is some point at which people quit, and I 11 wondered what it would take to be able to try to define what 12 that is? I mean clearly you want to run a calculation and 13 then you want some internal uncertainty assessments to come 14- . with it and things like that. () 15' What would be the mechanism to -- ignoring all the 16 . constraints, which can't be ignored but you could try -- to 17 establish some standards on these things? 18 MR. ELTAWILA: Let Ralph try to answer.
.19 MR. CARUSO: I am going to say I don't wan to 20 stop, okay? I am driven by Dr. Hochreiter's successors and 21 their customers who.are determined to improve their machine 22' iin every way they can. They are looking for ways to develop
- 23l new' spacer grids. -They are looking for new materials. They 24' are looking for ways to --
225 DR. POWERS: So you are a continuous improvement h (/ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 L
I 190 j 1 1 guy? 2 MR. CARUSO: Pardon? b)h Q. 3 DR. POWERS: You are for continuous improvement. 4 MR. CARUSO: Continuous improvement and I don't 5 think it should stop -- this is a personal opinion. In my 6 personal opinion closure is a dirty word in this area. 7 There shouldn't be any closure. 8 DR. POWERS: I like that. I mean like the turn-9 of-phrase. I don't know whether I agree with the sentiment, 10 but I like the turn-of-phrase. 11 MR. CARUSO: I'll write that one down. 12 DR. 20WERS: Closure is a dirty word in this I 13 business. 14 MR. CARUSO: I mean I haven't heard that word in a (% ( ,) 15 long time, but that used to be the term that used to come 16 out of the Office of Research was "We've got to come to 17 closure on the codes" and I said no. Nobody liked it when I 18 said no, but I still think that that is the right answer is 19 no, there is no closure, because you can't -- one of the 20 elements that Farouk has there is maintaining expertise. 21 Well, if you don't have interesting work for people to do, 22 the expertise goes away. 23 You have got to keep working on this stuff. You 24 can't stop. 25 CHAIRMAN WALLIS: You said you were -- [') ANN RILEY & ASSOCIATES, LTD. \, / Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
l 1 l l 191 1 MR. CARUSO: Westinghouse isn't going to stop. 2 DR. POWERS: I agree with you that Dr. 3 Hochreiter's description of the fuel elements and things 4 like that, some of the more exciting things I have heard in 5 a long time, and if we have that type of dynamicism in the 1 I 6 industry, you're right. You can't stop -- because they l 7 ~ won't stop. 8 MR. CARUSO: It is the dollar. That is what is j 1 9 driving it. 10 CHAIRMAN WALLIS: Well, I don't think that it is 11 quite the same game. Industry comes in with a code which 12 has all kinds of knobs that the user can twiddle because 13 they like it and they can predict what they want to predict. , 14 If you want to assess their one prediction that they show () ( 15 you, you may have to do a thousand by twiddling all these 16 knobs to seek sensitivities, so your needs are different 17 from theirs. It is not a competition on an equal playing 18 field. You really have other needs than they do. 19 MR. CARUSO: I do, but what I am saying is that it 20 is driven by this -- I won't say competition, but it is 21 driven by the fact that the industry is trying to shave 22 margins everywhere. 23 CHAIRMAN WALLIS: That's right. 24 MR. CARUSO: We are trying to build margins back, 25 identify margins by re-doing calculations in a different way b V ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
i 192 1 and we can check those results by doing lots of our own () 2 calculations, which we sometimes do, or we can make them go 3 through the sensitivity studies, which we sometimes do, 4 although they hate that with a passion, but they come to us 5 with some of these spacer grid designs. They come to us 6 with seven datapoints and say that is good enough for a 7 correlation. 8 MR. HOCHREITER: I've done that. 9 MR. CARUSO: See? j 10 DR. POWERS: You have five extra points more than 11 you needed. 12 [ Laughter.] 13 MR. CARUSO: I don't know where they are going to 14 find to attack the problem next. O) (, 15 DR. SCHROCK: They are notoriously short on 16 engineering analysis however. Can you cite some examples of 17 code developments that have come out of industry? 18 MR. CARUSO: Code developers that have come out of 19_ industry? 20 DR. SCHROCK: Analysis of the problems from the 21 first principle is what I am talking about. 22 MR. CARUSO: Good observation. That's not what 23 they are there for. I was going to make the observation 24 that the version of RETRAN we are currently wading through 25 the-swamp that we are wading through is a good example of i (\, \ l ANN RILEY & ASSOCIATES, LTD. ! Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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d 193 1 this, okay? It is a code that the industry is trying to ( ) 2 make do lots of things and -- 3 DR. SCHROCK: That is exactly my point. In the 4 interest of saving money, there is a near-refusal to do 5 analysis and so you have a code like RETRAN which is 6 presented as a best estimate code, which has no resemblance 7 to best estimate, none. 8 MR. CARUSO: You're right. It gets advertised as 9 a best estimate code but it has lots of problems. 10 DR. SCHROCK: We are talking about resemblance to 11 a best estimate code. If you look for resemblance to a best 12 estimate code there, you don't find it. One of the elements 13- are missing. 14 MR. CARUSO: I am not going to disagree.
) 15 CHAIRMAN WALLIS: And yet it is still being 16 considered. You know, it is still being evaluated and --
17 DR. SCHROCK: Well, I mean don't tell me industry 18 is doing all these great things when they present you with a 19 code like that with the label "best estimate" on it that 20 this simply means they have not bought into the concept of 21 what best estimate analysis really means and if they did 22 what value it has for now. They get the benefit essentially 23 by claiming that it is best estimate without doing anything 24 to make it such. 25 DR. KRESS: I want to return back to these I g ANN RILEY & ASSOCIATES, LTD. N Court Reporters 1025 Connecticut Avenue, NW, Suite 1014
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194 1 objectives, maybe just to -- but you say you're always going r i 2 to make it better, it's too open-ended. I thi1X what you (, 3 need to do is set interim goals on these things, interim 4 measures, and then, you know, if you want to make them 5 better, set new ones later. But what do you need right now, 6 and based on what you know about the regulatory th!.ngs 7 you're faced with? So I still would recommend some sort of 8 metric on what you mean by these things. f 9 MR. ELTAWILA: Okay. I don't think there would be I 10 a problem at all giving you a metric about the things, but, l 11 you know, it's just in a nutshell, when we have -- j 12 CHAIRMAN WALLIS: It's a real problem, Farouk. If I 13 you have a metric, someone will actually measure your
]
14 performance against what you said you would do. 15 MR. ELTAWILA: No, no , I have no problem measuring 16 .my performance against what we are doing. Just give me the 17 resources. We said we were going to consolidate the code. 18 We said we were going to make the code run faster and more 19 robust. Unfortunately, because of the budget cut and things 20 like that, we have a delay in schedule. But are we going to j 21 achieve this goal? There is no doubt in my mind that we are 22 going to achieve -- 23 CHAIRMAN WALLIS: How much faster is it? 24 MR. ELTAWILA: Huh? 25 CHAIRMAN WALLIS: One percent faster, 100 percent, bV ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 m 1
f 195 1 10 times, 100 times? 2 MR. ELTAWILA: Well, first, right now, it is going 3 to come out of the idea of the robustness of the code. If 4 you get the code to run to completion without continuously 5 failing, then I achieved a good, a fast-running code right 6 now. But in the long term, the improvement in fashioning of i 7 the code is going to be in parallel processing. 8 Professor Mahaffy is going to talk about some 9 changes that he made to the code that will help us to make l 10 the code run faster. How much faster? I can't tell you l 11 that until we put it -- finish all the work that we are j 12 supposed to do and assess the code. Although Jennifer might 13 have some indication of how fast the code is running right 14 now. l 15 DR. KRESS: What we'd like to see is do I want 16 this thing to run in real time, or do I want it to run ten 17 times real time? 18 MS. UHLE: Jennifer Uhle, Research. I mean, it 19 depends on -- 20 DR. KRESS: The application. Of course. 21 MS. UHLE: If I'make, you know, a vessel with six j 22 nodes, yes, it's going run fast, but if I make, you know, an 23 AP600 vessel with what, 400 or whatever it turned out to 24 be - l 25 DR. KRESS: But I'm assuming that you're going to j [ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 j (202) 842-0034 ! l j
1 196 1 make it so it has the correct accuracy and the correct (~D 2 robustness, and all those things together will determine
%-l !
3 those. And in the meantime I'd like for it to run maybe ten I 4 times real time. Why? Because'some of the sequences that 5 are run for some of the cases go out to 30 hours. I don't 6 want to wait 30 hours, I want to get it done in 3 hours. 7 But some rationale like that would lead you to a target. I i 8 don't know how long -- how fast it runs now. What I do want 9 'to know, I want to know how fast I need. 10 DR. POWERS: I think the thing we're talking about 11 here -- I think I agree with you about your interim 12 measures, and I think maybe the interim measure that you're 13 talking about first of all is one they'd like to run a 14 problem from soup to nuts. () ( ,j 15 DR. KRESS: Um-hum. 1 16 - DR. POWERS: Okay. And they really don't care how j l 17 long it runs, just as long as it happens without falling I I 18 apart. That's the interim goal. l i 19 DR. KRESS: That's where I would be. 20 DR. POWERS: Then they might -- they may have to 21 do that before they can answer the next question of how fast 22 does it go, and so it may be interim and not doing it all 23 but doing some subset of those first. 24 I hasten to bring up an anecdote. About four 25 years ago I was reviewing another kind of thermal-hydraulic
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ai 197 1 code from nuclear energy on a very, very short time ) (A) 2 schedule, and after 24 hours on the biggest Cray that 3 existed at the time, they succeeded in running a few shakes, " 4 which is a few atomic vibrations, and the guy was very proud 5 of it. He had a fast-running code. In 24 hours he'd run a 6 few tonic vibrations on this. 7 CHAIRMAN WALLIS: Well, I would like you to be , i 8 user-oriented. I'd like you to set up specs, satisfy an l I 9 order for let's say a typical NRR guy who has to assess 10 something, wants to ask certain questions about what happens 11 in certain transients, get an answer let's say in an 12 afternoon. If that is what it takes for that person to take 13 your code seriously and use it, then you've got to provide 14 it, because if you don't provide it, he won't use it at all. A (_) 15 So you've got to figure out what the user would like to have 16 in this code, and a name for it. I haven't see that at all. 17 MR. ELTAWILA: You have not seen that at all? ! 18 CHAIRMAN WALLIS: I have not seen someone -- 19 MR. ELTAWILA: Maybe'I -- 20 CHAIRMAN WALLIS: Try to specify or have a vision 21 of whatever the code needs to do in order for usere to 22 really find it useful. i 23 MR. ELTAWILA: If you have a user that has a 24 ' problem when the -- not be able to modify an input deck to 25 address the situation at hand. If you have a user that [\~ hj ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 L
I I i 198 1 cannot run the code to completion, if you have the user will () 2 not be able to tell if the answer that's getting out of the 3 code is a good answer or not, you translate that into a 4 requirement and objective, and the objective reflects what 5 the user said. And I said that repeatedly. If I did not 6 succeed in relating this information to you, maybe I will 7 put it in writing and send it to you, you know. But -- 8 CHAIRMAN WALLIS: I think you should. This would 9 really help our report, if you can cast it in the form of 10 what it is that you or your users have got together and 11 decided this is what we need to have as a package in order 12 to do all these things that the Agency wants --
.13 MR. ELTAWILA: You translate the user into a 14 requirement. User need translated in the requirement. And
( 15 the requirement translated into objective. And I stated the j 16 objective. What additional information you're looking for, 17 I'm just really at a loss right now. 18 CHAIRMAN WALLIS: Well, I think it's at too 19 general a level for me. I think you need to go to the next 20 step. 21 DR. SCHROCK: One of them war identified. You 22 definitely wanted to be able to complete a problem without 23 interruption. You ought to state that as an objective. 24 MR. ELTAWILA: We state it several -- you know -- 25 DR. SCHROCK: No , I mean in this written [)/ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 1
199 1 description. [U ) 2 MR. ELTAWILA: It is written -- we really had it 3 written several times. Look at the 1996 research plan. We 4 would like the code to run to completion. We said it-5 several times. 6 CHAIRMAN WALLIS: That's a pretty minimal 7 requirement. 8 DR. SCHROCK: Oh, I've heard you say that many 9 times. That's not the point, Farouk. The point is that 10 when you put down a formal list of code requirements, that 11 ought to be kind of the first one. 12 CHAIRMAN WALLIS: It's a sine qua non. 13 DR. SCHROCK: The code must be able to run without 14 interruption. b( ,e 15 MR. ELTAWILA: Are you going to say that, 16 Jennifer? Jennifer will sat it in her presentation. 17 CHAIRMAN WALLIS: It must not blow up. It must 18 not crash. 19 DR. POWERS: I think I'm very sympathetic. I can 20 see a set of qualitative requirements, and if -- the problem 21 is that the code doesn't run to completion, and that's not 22 unheard of in some of these codes, to have that, and he says 23 okay, that's my objective, get the damn thing to run from 24 the beginning to the end of a problem, and that's the only 25 ' quantitative goal I can set right now, because nothing ANN RILEY & ASSOCIATES, LTD. N- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 1
E L U , 200 1 1 else -- it makes no sense to sit down and talk about how ' () 2 fast it runs if it were run at all. It runs and there's 3 problems, I don't have any troubles with that as an interim 4 measure. 5 Now, it would be nice if you could go on and say 6 do what you're talking about and say I've sat down with 7 these guys, they're going to use it, and we dreamed for a 8 while and said, you know, if we can have what's our heart's 9 desire, we'd like to be able to run these calculations, 20 10 of them every 10 minutes, and have the results collated and 11 a report printed out with all the graphs as the output. And 12 I can pick it up out of the printer. I mean, I think that 13 would be fine, but I'm also sympathetic with the more 14 interim measure. n () 15 CHAIRMAN WALLIS: Yes, but while you're struggling 16 with the first thing about making a run to completion, you 17 could probably make it run to completion if you put in all 18 kinds of tiny time steps and everything, you may actually 19 prevent some of the other goals from being satisfied by 1
- 20. doing things in order to make sure that it always finishr3.
21 It may take a year to finish, in that case. 22 DR. POWERS: I mean, having participated in the 23 development of a lot of these codes, you do that. That's 24 exactly what you do. You put in the patches and things like 25 that. It gets you through once, and then you go back and i ANN RILEY & ASSOCIATES, LTD. [/
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a 201 1 you say now, since clearly running for a year and a half is ( ) 2 not excessive, and I've had some run for six weeks on a 3 Cray, that you sit down and say now since that's 4 unacceptable, which ones of these are causing the problem? 5 And actually there's pretty nice software associated with 6 most of the compilers nowadays to tell you where you're 7 spending yaur time. And people do go optimize and things 8 like that. 9 MR. ELTAWILA: So you're asking me to -- you want 10 me to provide a definition of what we mean by robust, run 11 fast, you know, that's what you want a definition for this. 12 CHAIRMAN WALLIS: I think it would be good to have 13 more definite specifications, and I think they should say 14 something about users. They should bring in a user. Put (~T g,) 15 yourself in the position of that guy sitting there with some 16 questions. How is this code going to be used by this 17 person? What pictures would you like to have? 18 MR. ELTAWILA: Do you think we are developing this 19 code in a vacuum, or what? 20 CHAIRMAN WALLIS: I don't know, Farouk. It just
.21 seems to me that --
22 MR. ELTAWILA: You must have a reason -- 23 CHAIRMAN WALLIS: All of this comes from you. I 24 don't have somebody -- I don't have the user perspective. 25 MR. ELTAWILA: I'm sorry that I disagree with you, [ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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1- Professor Wallis, because I gave you a report that has the 2 information that the user requests.
'3 CHAIRMAN WALLIS: I don't want to get into this 4 tone, because I think you've been very responsive and very 5 helpful. I'm trying to be helpful. I'm not trying to j 6 criticize. And I really don't want -- I'm just saying if 7 you had more specifics about what the user is really looking 8 for, it would be very helpful. I think you'd find it would 9 make your job easier, 10 MR. ELTAWILA: You're not satisfied with the 11 information that we give you about what the user needs? If 12 you're not satisfied, I will get you more information, but I 13 cannot --
14 CHAIRMAN WALLIS: I'm not sure if you're the 15 person. It may be the user who needs to do some of this. 16 But -- yes, I would like to see more. Yes. I think you've 17 done very well so far. 18 MR. ELTAWILA: How does the code consolidation 19- effort relate to the Agency goals? You've seen these four 20 goals before: reduce unnecessary burden, maintain safety, 21 make the Agency regulatory decisions effective, efficient, 22 and realistic, and if the Agency maintains safety and is 23 effective and uses realistic decision, that will increase 24- public confidence. That's why you find it. And I think I 25 got that comment from the ACRS during the research ANN RILEY & ASSOCIATES, LTD. G\ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 1
1 i l ! l 203 l 1 presentation. Public confidence is an outcome of the other i es \
\ 2 two activities, so it's underneath the other two.
.O 3 The issue, we are saying that the code 4 consolidation is essential to maintain long-term thermal-5 hydraulic analysis capability to meet Agency needs and cope 6 with budget reductions. I really don't think we can deal l 7 with the status quo we had in the past, so consolidation is 8 essential. 9 What's the accomplishment that we're going to get 10 out of the consolidation? A reliable, independent, more 11 accurate best-estimate thermal-hydraulics code to be used by 12 the Agency to support regulatory decisions. And we feel 13 that that will contribute directly to the above goals. 14 I would like to add one thing, because I think ,q k,) 15 maybe it's time to talk about it. You make an assumption 16 that the user is only NRR. If that's your assumption, you 17 are not right about that, because the Office of Research 18 uses these codes more than NRR. We are in charge of 19 resolving safety and generic issues. We have done all the 20 analysis for the AP600. So don't think that we are not a 21 user. We are not only a code developer, we are using the 22 codes too. 23 What are the benefits to NRC from the TRAC-M code? , I 24 It will eliminate the need to spend efforts on four codes. 25 In terms of code development, assessment, maintenance, input i I () A-e ANN RILEY & ASSOCIATES, LTD. Court Reporters , 1025 Connecticut Avenue, NW, Suite 1014 l Washington, D.C. 20036 i (202) 842-0034 i d ! .
p- i f i 204 1 deck preparation, development of in-house expertise, we are p)
- 2 planning to expand the assessment because we will have a tj 3 single code so we will be able to expand the assessment of 4 the code, and I'm making a statement here that the current 5 codes are minimally validated as opposed to sufficiently or 6 fully validated. It is lousy validation testimatics that we 7 are using for the codes.
8 Provide NRC with independent capability. We use 9 this code to assess vendor and licensee submittals. We're 10 using it to assess operating events and implementation of 11 risk-informed regulation. And respond to industry 12 initiatives like increase core power levels, longer 13 operating cycle, and new fuel designs. 14 We are using the code for resolution of safety 15 issues. These are the three issues that we are dealing with 16 right now: pressurized thermal shock, boron dilution, ATWS, 17 and BWR stability. And again, just by having the NRC 18 thermal-hydraulic code used by the international community, 19 we are getting in-kind contributions in terms of more people 20 using the code, identifying deficiencies in this code so we 21 will be able to fix it, and at the same time we're getting 22 some cash contribution from these countries. 23 Why code improvements are needed. I think 24 hopefully that the message that we've been saying is clear 25 right now that the answer obtained by the Thermal-Hydraulic / ANN RILEY & ASSOCIATES, LTD. \~ ') Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 I i i a
T i 205 1 Code can vary dramatically because of the empirical 1 () 2 3 correlation in the code, the user option, compensating error, and in certain cases we don't have sufficient 4 understanding so we cannot put model in the code. 5 When we see evidence from experimental data, we'll 6 try to.model events resulting from experimental programs -- 7 CHAIRMAN WALLIS: It seems odd to me that if this 8 is true, which I think it is, that these codes' answers vary 9 dramatically, that your users aren't screaming and saying
'10 these aren't good enough, we need a lot more work to get 11 them better.
12 MR. ELTAWILA: Okay. You can direct that question 13 to the user behind you. If they don't want a better code, 14 we --
) 15 CHAIRMAN WALLIS: You're not worried by the fact 16 that things vary dramatically? I mean, this would make 17 . them, I would think, pretty insecure.
18 MR. ELTAWILA: Well, the user is behind you. I 19 will give them the opportunity to answer that question,
-20 Graham.
21 NRR wants to answer that question? 22 MR. CARUSO: We are always in favor of 23 improvements to the code. I just, you know, I just said it. 24 We've always been in favor of continued research ; i 25 to improve the models in the code, because we are being 4 1 [/) A-ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014
. Washington, D.C. 20036 (202) 842-0034 1
r' t 206 1 driven to do more detailed analyses by the industry, by the Im\ 2 way the industry is advancing. O 3 CHAIRMAN WALLIS: I get the sense that that the 4 push to improve the codes is coming very much from the 5 people doing the work, and they're not under great pressure 6 from the users to get on with it and give us something 7 better. 8 MR. ELTAWILA: No, you are wrong about that. 9 CHAIRMAN WALLIS: No? 10 MR. ELTAWILA: You're wrong. l 11 CHAIRMAN WALLIS: Okay. That's good. So maybe we 12 could see more evidence for that than we do see. l l 13 DR. POWERS: I am intrigued by a misunderstanding 14 of phenomena. It seems to relate very directly to our A ( ,) 15 discussion on experimental facilities. Do we have some idea , 16 of the length and the breadth of this incomplete 17 understm. ding of phenomena? l 18 MR. ELTAWILA: I think the presentation by Larry l 19 and Jennifer will give you some hints about the I 20 understanding of certain phenomena. 21 DR. POWERS: Because, I mean I am not immune to 1 22 what I will call the Apostolakis phenomena that says 23 thermal-hydraulics is basically an understood science and it j 24 is just a problem of modeling it. But if we are having 25 troubles with phenomenology, then that puts a bigger O-/ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i A
m ; . 1 p 207 1 imperative on experimental programs than maybe I have i (} -2 appreciated up till now. So anything you can do to help me 3 on that will help a lot. 4- CHAIRMAN WALLIS: I think you can find many 5 examples of this. You can take the sort of interfacial 6 friction factor that is assumed in stratified flows or 7 annular flows, you will find different people's models are 8 all over the place. 9 DR. POWERS: Yeah, but that is what I would call a 10 modeling or a correlational issue rather than -- 11 CHAIRMAN WALLIS: But the phenomena aren't 12 understood either. I mean the correlations are all over the 13 place because none of them represents phenomena, because the , 1 14 phenomena are not understood. )
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y) 15 DR. KRESS: They get involved with related j l 16 formations and interface and sheer stresses that you haven't ' 17' dealt with. 18 DR. SCHROCK: Many multi-dimensional effects that 19 are just not addressed at all in the schemes. 20' DR. POWERS: It would be useful to understand. I 21- certainly appreciate the kinds of problems that. Larry was 22 talking about, where you have got new and unusual 23 configurations and things like that. That, I mean I have to j 24 admit that is really exciting. 25 MR. ELTAWILA: We are going to be using these 1 [\/ } ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014
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l 208 1 codes in a way that we never used them before or we never () 2 3 intend them to be used this way. For example, quantification of the safety margin and uncertainty to 4 support risk-informed regulation. We have been asked by the ; 5 people in charge of making Part 50 risk-informed to identify 6 candidate area of revision to. regulatory requirement. 7 Some of the questions that they are asking us are 8- -- Where there are excessive margin in acceptance criteria, 9 and/or method and assumption used in the analysis? They 10 want us to identify that. Identify current source of 11- uncertainty, their estimated magnitude and what should be 12 done to reduce them. They are requesting information about 13 revised acceptance criteria, where new information or 14 technology indicate that revisions should be made to 15- requirement. 16 If we have to answer all these questions, I say 17 that our existing capability will not be able to answer any l 18 of these questions. Is that a strong enough statement? If 19 it is not -- l 20 CHAIRMAN WALLIS: So what is the agency going to 21 do if you don't? ; 22 MR. ELTAWILA: We are trying to bring the I 23 analytical tools of the agency to the level that they can be 24 used for that. Whether the agency will be patient until 25 this information in place, or they are going to give away ANN RILEY & ASSOCIATES, LTD. O* Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 i Washington, D.C. 20036 (202) 842-0034 1 1 i
I I 209 1 the margin, that is something we should be asking other
) 2 people.
3 CHAIRMAN WALLIS: You said that your current tools 4 can't really be used to answer these questions. 5 MR. ELTAWILA: Yes, they cannot. 6 CHAIRMAN WALLIS: The agency seems to be pushing 7 ahead trying to answer them. 8 MR. ELTAWILA: Yeah, the train left the station. 9 And so -- 10 CHAIRMAN WALLIS: Yes, but we have already 11 established it doesn't have a track, so -- 12 MR. ELTAWILA: That's true. Yeah. 13 CHAIRMAN WALLIS: No, it seems to me this is very 14 key. I mean you are telling me that -- you are telling this () 15 committee that you can't answer these questions. That would 16 seem justification for getting whatever resources it takes 17 to get the answers. And yet that doesn't seem to be 18 appreciated in terms of the budget makers. Or maybe budget 19 isn't the answer, maybe it is somewhere else. 20 MR. ELTAWILA: No , it is budget is the answer. 21 Budget drive everything around here. So anybody tell you 22 otherwise, I think that it is just not -- 23 CHAIRMAN WALLIS: But if this is something that is 24 holding up something the agency wants to do, and if you 25 don't do the work, it is going to be held up. ANN RILEY & ASSOCIATES, LTD. [~') V Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 j
r s 210 l 1 MR. ELTAWILA: Maybe the agency has a different (-s) 2 plan'. I am telling you about from my thermal-hydraulic 3 perspective, I say that our codes will not be able to
)
l 4 provide them with this information. 5 CHAIRMAN WALLIS: But this is a chasm that the 6 train has to cross and you have got to build a bridge, 7 right, that is what you are saying, and the agency doesn't 8 seem to realize it. 9 MR. ELTAWILA: They might have a different plan 10 than what I have. 11 CHAIRMAN WALLIS: They don't have a budget for the 12 bridge. 13 MR. ELTAWILA: No , they might. They have great
'14 plans and they can address it without our thermal-hydraulic ,
c' 1 ( ,)/ 15 codes. 16 CHAIRMAN WALLIS: But if there is no budget for 17 the bridge, the train is going to fly across the chasm, 18 right? 19 MR. ELTAWILA: Well, it would be faster than what 20 is going right now. 21 DR. POWERS: Remember, the difficulty, the 22 challenge that is always faced is that, yes, NRC can always 23 make a decision. 24 DR. KRESS: They can make a decision. 25 DR. POWERS: Always make a decision. They may not [~)
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lf 1 i l 211 1 make the best technically informed decision. They may not [/} u 2 make a decision that promotes efficiency and both safety in 3 the production of electricity, but they can always make a l l 4 decision. And, yeah, I think it is a legitimate concern to l 5 say, will they have the patience to develop the technology 6 to make a technically refined decision or not? 7 I think we have grown to appreciate that in the 8 interests of reducing burden and focusing safety, that 9 sometimes you are going to have to have the patience, or the 10 resources, to do some of these things. i 11 MR. ELTAWILA: If you want to have public i 12 confidence in what we are doing, we have to base it on the 13 best available information. 14 DR. SCHROCK: Farouk, what is the status of ( 15 documentation on the code? (_j 16 MR. ELTAWILA: Jennifer is going to go over it. I 17 really think it is improving, but I will let Jennifer give 18 you the presentation. 19 DR. SCHROCK: Well, that, of course, was a major 20 problem on the codes developed in the labs, and I don't 21 expect it will be different here. What you have presented 22 is a nice concise description of how you have gone about 23 putting together a new version based on some new things and 24 some old things. But we probably each have a different 25' interpretation of what some of the words you have used mean. ANN RILEY & ASSOCIATES, LTD. [(..)/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 h
7 l 212 1 .An example, quantification of uncertainty. You -(' (.)
) 2 want that to come out of the code. I think that is a
'3 laudable aim, but I don't visualize what you mean when you 4 say those words, how you think that --
5 MR. ELTAWILA: If you look -- I appreciate, you 6 are correct. 7 DR. SCHROCK: Okay. Yeah. 8 MR. ELTAWILA: With respect to the documentation, 9 Jennifer will talk about it. It was really a very expensive 10 process that we have to go through, through the 11 consolidation, and she will go over the details. But just 12 not to mislead you, the area of quantification of 13 uncertainty, it is a long-term effort, we did not even start 14 thinking about it, really, because I don't have the I (_j 15 resources or know how I am going to do it,' you know, but it 16 is one of the user requirements and we are going to get 17 there. 18 So just to give you some example about why code 19 improvements are needed, and I think it is Einstein who said 20 that.you cannot solve a problem with the same data that 21 created them, right. 22 [ Laughter.] 23 MR. ELTAWILA: And that is what we continue to do 24 here at NRC. We identify the problem, we solve the problem 25 with the same tool that identified the problem. Okay. That ANN RILEY & ASSOCIATES, LTD. h) (/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 b l
i i 213 1 is why we need tieparate effects tests. And the issue is 2 accurate modeling of plant thermal-hydraulics is vital to I V 3 quantifying safety margin and uncertainty necessary for l 4 risk-informed regulatory decision, significant constitutive 5 model improvements are needed before issues are pursued. 6 That is the issue. 7 The planned accomplishment is to eradicate l 8 deficiencies in the TRAC-M code capability so NRC can l 9 quantify the safety margin to make technically sound 10 decision when adding provision to make Part 50 risk-informed 11 and to address emerging issues. Believe it or not, these 12 were the motivation for the separate effects test program in 13 1995, even before this risk-informed Part 50 became 14 involved, but that was the motivation behind it. And, 15 again, we feel that if we complete the separate effects test 16 and we improve the code, we will be able to satisfy the 17 above stated goals. 18 Jennifer, are you going to go over the dynamic 19 flow? I will just show you here, Jennifer is going to go -- 20 CHAIRMAN WALLIS: I was wondering -- I am sorry, 21 Farouk. I think these are very good. I think when you 22 start looking at it in detail, take any example, like, say, 23 interfacial friction factor modeling and annular flow, you 24 cannot simply say we are going to have an accurate model. 25 And people have worked on this problem for 40 years or O ANN RILEY & ASSOCIATES, LTD. (d Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
214 1 something, and there doesn't seem to have been much progress () 2 in getting more accuracy. So how are you going to mysteriously get accuracy where it hasn't been acquired 4 before for 40 years? 5 There is still a scatter of 50 percent or 6 something in the data. It hasn't come down with time. 7 MR. ELTAWILA: I think we would like to, as I 8 mentioned to you, we would like to have you visit some of 9 the work. We will go and visit the Purdue facility, looking 10 at their interfacial area transport. Jennifer is going to 11 show you an example for one flow regime about improvement in 12 the model that already can be done. So that is a quick 13 answer. 14 And the second answer, if you say that because we () 15 did not succeed in the past to do something, we should stop 16 now, if that is your view, please let me know and we will 17 stop it. 18 CHAIRMAN WALLIS: No, no, no. I was just 19 looking -- 20 DR. KRESS: The data scatters so much. ! 21 CHAIRMAN WALLIS: I was looking at the data 22 scatter so much. The repeatability is not so good, your 23 dependence on things which are not defined in the 24 experiment. It is also true in the theories. And in the > 25 past, these major threads of research in two-phase flow had f~) -\_/ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 6 .
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215 1 far more resources behind them than you have now. A lot of () 2 very smart people who think worked on these problems. 3 MR. ELTAWILA: Absolutely, and we are not -- but I 4 think there are better instrumentation nowadays. We know 5 the model that will be needed for the code so we try to make 6 the experiment really go after the models so it can improve 7 the model for reactor application rather than for the sake 8 of developing model for -- 9 CHAIRMAN WALLIS: Yeah, but I think -- yeah, you 10 need to think pretty hard about that. If you look at models 11 for any part of two-phase flow, like interfacial area or 12 bubble drag and so on and so forth, you will find that there { 13 were some contributions made a long time ago and they seemed 14 to improve things. There has not been much improvement for f3 (_,) 15 a long time. And I don't see it coming out of the 16 universities now. So where is it going to come from? 17 You may have a great ambition and you may find you 18 are stuck without the resources to do all that it takes to 19 really get those'models improved. 20 DR. POWERS: I mean if I look at the next -- on I 21 one of those viewgraphs in here, I mean I see one curve from 22 one model that is not even close, and I would see another 23 one that in the source term world would be considered 1 24 perfect agreement. 25 CHAIRMAN WALLIS: That is a big improvement. , \/~) ANN RILEY & ASSOCIATES, LTD. s ./ Court Reporters 1025 Ccnnecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 j i
I s 216 1 MR. ELTAWILA: What is important, look at the () 2 3 trend the data. The data shows that the interfacial area is decreasing with L over D, but the code trends is increasing. 4 What kind of confidence do you have in a code that is not 5 even predicting the trend on the data? Not even -- never 6 mind the data itself, the trend in the data. 7 CHAIRMAN WALLIS: So why should I consolidate it 8 with anything else if it is so bad? 9 MR. ELTAWILA: Economic. We have two issues. You 10 cannot complicate, you cannot combine the two issues. We 11 have economical issue that we say we can not maintain four 12 separate codes. So the first phase is to consolidate these 13 codes to make them one code. The second phase is start 14 improving-these models. O( j 15 CHAIRMAN WALLIS: You might find another plot 16 where it is reversed, because RELAP actually does better 1 17 than TRAC. I 18 MR. ELTAWILA: Absolutely. 19 MS. UHLE: Not in this particular one. Well, no, 20 I mean -- this is Jennifer Uhle again. I think, you know, 21 when you are talking about accuracy of the models, I mean 1 22 think a lot of the times in the codes, what is difficult now 23 is that when you are looking at one particular phenomenon, 24 you have more than one physical, what you call model and the 25 code that is working together to produce this void faction O, ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
i 217 1 prediction that we plot versus data. ,n s v 2 And, you know, in the past, when the analysis was 3 done, people did not, say, look at more fundamental -- look 4 at the problem in a real fundamental sense, where, you know, 5 is this trending in the right direction? I know they relied 6 more on compensating errors, predicting the global void 7 fraction rather than, you know, was the interfacial area 8 going in the right way, so, therefore, the compensation term 9 is properly predicted? And then, you know, drag has an 10 effect. I mean I think we could do a lot by making these 11 models more physically based by taking a step back and just 12 making sure that, you know, we are not relying on these 13 compensating errors. 14 And so, yeah, maybe we still don't know exactly D) (, 15 what the friction factor is in' annular flow, but, you know, 16 to the fifth decimal place, but at least we would be getting 17 the proper trends. And there has been a lot of cases in the 18 codes where you can point and say we are really not modeling 19 reality at all, we are just hoping that when the models all 20 add up together we are going something that looks all right. 21 .And when that happens, you worry about scaleability and you 22 worry about-really having to spend more time really 23 validating your model, I mean validating the code, because 24 you are not real sure of it outside of any of the data that
- 25. you are compared it over.
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I 218 1 So I mean I think that, I don't know, maybe [) V 2 accuracy is -- and I see what you are saying, it is hard to 3 say if you are going to become more accurate. But at least 4 you can become more physically based. And, you know, in the 5 past, that I don't think was focused on. I mean maybe it 6 was, I wasn't around to see it. 7 MR. ELTAWILA: Thanks. If you look at this year, 8 it is a comparison between the data from the APEX facility 9 for dryout experiment. Here is the RELAPS code. If you 10 rely on a single code calculation, which most of the time we 11 will have to do, you find that the code actually did not 4 12 predict dryout, but there was a dryout in experiment. Is 13 that code acceptable for us? Again, that was due to 14 deficiency in the face separation model and we are running ( 15 experiment to expand the data to cover the range of 16 applicability, the range that the model is used for. 17 Again, I am not going to go over all of them. 18 Just another plot here that shows -- here is the Appendix K 19 value, here is the old CSAU methodology. You have seen that 20 plot before. We used to have a lot of margin between the 21 CSAU and the Appendix K limit, but due to the increase of 22 the linear heat generation rate, which all industry is 23 going, you can see that the calculation right now is 24 approaching the limit. So we have to be very careful about 25 the model that we are using in reflood, and that, I think [D ANN RILEY & ASSOCIATES, LTD. \ms Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
3 1 219 l 1 Larry is going to discuss that in his presentation. 2 Again, here a sample of -- you have seen it
)
3 before. Here is a TRAC calculation, here is the data. The i 4 code keeps the temperature continuing to increase, the data 1 5 already shows indication of the cooldown. Again, you can 6 reach or make the whole regulatory decision when you have -- l s 7 your totals are like that. 8 I think Jennifer talked about compensating error.. 9 Here is, again, the subcooled boiling model. You can see I 10 the comparison between the data and the code. There is no 11 relationship where the code is predicting the data at all. l 12 Now, what makes it worse, if you look at the 13 actual, the individual model into that model, you see that 14 the code in one case under-predicted the data, in the other 15 case, in the other model, over-predicted the data. You get 16 a compensating error. 17 CHAIRMAN WALLIS: So one would be tempted to say 18 the code -- that the theory has nothing to do with the 19 results, it is off by two orders of magnitude. ., 20 .MR. ELTAWILA: And that is why we are trying to 21 improve things. I am trying to help you with just a 22 rationale of why we are trying to improve things. And I 23 think Jennifer is going to go over this one. It is nice to 24 try to delegate the rest of the complex issue to Jennifer 25 here. O ANN RILEY & ASSOCIATES, LTD. ld Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 . (202) 842-0034 ) l l
1 i 220 1 In terms of how ongoing activities are related to (em 2 the performance goals stated in the Commission, you can see 3 v). 3 that every single activity we have is related to one or more 4 of these performance goals. I really am convinced that that 5 the only way we can achieve public confidence if we have 6 assessed the code adequately is that we can stand in front 7 of a group like this group and say that we really feel that j 8 we have an adequate assessment. I cannot make that 9- statement today. ; I 10 CHAIRMAN WALLIS: One way you could get more l 11 public confidence is if my students could use your codes on 12 their research projects and the results came close to what 13 they observed in experiments, not for nuclear purposes 14 necessarily but for just thermal-hydraulic purposes -- step rh ( ,/ 15 outside the nuclear box. 16 DR. POWERS: Yes, but I think that is the most -- 17 is a very inefficient form of public confidence. 18 CHAIRMAN WALLIS: Oh, it's just an idea I had -- 19 if you get in a nuclear box you get probably confidence -- 20 DR. POWERS: It seems to me that the real issue is 21 the one that Farouk mentioned abbreviatedly earlier, that by 22 far and away most of the public really have -- now nobody 23 has less understanding of thermal-hydraulic than I do, but 24 equivalent understanding of thermal-hydraulics -- 25 CHAIRMAN WALLIS: I have far less understanding
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221 1 than you do, because I understand what I am confused about. lq j 2 [ Laughter.] 3 DR. POWERS: The responsibility really lies in the 4 Staff being able to say what Farouk just said -- I forget 5 what your words were exactly -- but you have a code that you 6 have confidence gives an adequate description of the 7 physical system. 8 MR. ELTAWILA: That's correct. 9 DR. POWERS: I think that it is asking too much to 10 have a code that can be used for routine analysis of 11 laboratory exp'eriments at universities. I mean I think 12 that -- 13 CH7IRMAN WALLIS: But it would increase public 14 confidence. I am not saying this is a requirement. The ( 15 more you can step outside the regulatory box where it's sort 16 of regulated that this is okay because we say it is okay -- 17 that's not a public challenge. That is an internal 18 challenge. If you submit yourselves to public challenge you 19 might increase credibility. 20 DR. POWERS: It might be an interesting discussion 21 we could have on that. 22 CHAIRMAN WALLIS: I wish we had all day, because I 23 think we could pursue all of these questions. 24 MR. ELTAWILA: No, I regret to say that I am going 25 to keep you here as long as it takes -- O)
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1 222 1 [ Laughter.] A ( ). 2 MR. ELTAWILA: -- because I think you are 3 punishing me.right now. 4 CHAIRMAN WALLIS: I can dismiss you in a split 5 second. 6 MR. ELTAWILA: No, I know that. 7 -[ Laughter.] 8 MR. ELTAWILA: Just a concluding remark. I I 9 believe that NRC must have an analysis tool that can be used 10 with confidence to support its regulatory decision in a 11 timely, effective and realistic manner. This is one of our 12 . goals. I 13 NRC action would have the utmost respect for and ; 14 confidence of the public, those it regulates, and other A (._) 15 stakeholders when we make this decision in a timely and 16 effective and a realistic manner. You can always say I am 17 going to be conservative and apply conservatism here does 18 not help you at all. 11 9 In addition to help our standing with the 20 stakeholder, it will also help our standing in the , 1 21 international-community, which has been in decline, and I 22 think some people say it has already declined and it can 23 never come back, you know? 24 We feel the design basis envelope of operating 25 plants has changed significantly over the years and will ANN RILEY & ASSOCIATES, LTD. [] k- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 i Washington, D.C. 20036 l (202) 842-0034 : i i
l i 223 1 continue to change. The plants that we designed 20 and 30 () 2 years ago are not the same plants that they are operating today. 3 There are more complex issues that require us to 4 deal with them with better tools than we have right now. 5 DR. POWERS: I cannot understate how important I 6 think this one is. When you talked in your opening slides 7 about maintaining safety, it seems to me that is the point 8 that needs to come up. It's not adequate for the NRC to 9 say, okay, we will maintain safety by doing the things we 10 have done in the past, not just because of things like 11 vessel embrittlement, PTS kind of phenomena, but you have 12 these developments that Larry has been mentioning here. 13 They are not going to happen. 14 You know absolutely the licensee is going to come O(,j 15 in because it's a big box for him and it's a box that he 16 needs to survive and you can't do the things that you have 17 done. You have to do better. 18 I think that is really an extraordinarily 19 important point. 20 MR. ELTAWILA: Thank you. I agree with you. 21 I think there is another underlying theme of 22 importance here. If the NRC does not do its own research, I 23 believe the industry will have no incentive whatsoever to do 24 research for two reasons. They can come here and they know 25 that the Staff is equipped here with obsolete information. ANN RILEY & ASSOCIATES, LTD. w- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i i L - !
i 224 I 1 They are not on top of things and they will fool us, to be () 2 3 honest with you. They can come and do that. The other reason is they feel that the Staff, if it is really well- l 4 informed about'the state-of-the-art of the different things, l 5 they might not be amenable for changes, so they will not do l 6 their own research, so it has an effect on the industry. 7 If anybody cares about this industry, they'have to
)
8 look at that. The industry is satisfied right now. They l l 9 would like to keep the analysis and all this stuff. The l 10 vendor would like to sell more fuel, MOX fuel. All these 11 factors will inhibit research in general. In the past the 12 industry were embarrassed into doing research because they i 13 knew the NRC is going to be smarter than them and they are 14 going to ask them the hard questions. () 15 The activities requiring thermat-hydraulic 16 expertise are mounting. I mentioned the implementation of 17 risk-informed regulation, the occurrence of operating 18 events, continuation of licensing amendments to modify tech-19 specs, resolution of safety issues and vendor and licensee 20 will continue to submit topical reports and the codes for 21 Staff review. I know that our friend Joe Kelly went to 22 Siemens for the methodology. It is going to come here to 23 the Staff for review, so we better be equipped for that. i l 24 CHAIRMAN WALLIS: We will unpack a review that he 25 did of a similar code. I I ) ANN RILEY & ASSOCIATES, LTD. ' \~ / Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 i (202) 842-0034 l l 1
r i 225 1 MR. ELTAWILA: So that complates my presentation. 2 I am ready for additional questions, if you have them. Ll( ) l 3 DR. POWERS: I think you like these questions, c l 4 MR. ELTAWILA: They are great questions but, to be I 5 honest with you, if I lost my cool -- which is very easy to 6 happen -- it is because we really, everything that you asked 7 for, we tried it, and we try to communicate as much as we 8 can, but you have to understand the constraint that the 9 Staff is under. It is not an easy job. 10 CHAIRMAN WALLIS: That is why you have it. 11 DR. POWERS: I mean in all fairness, I think this 12 is a pretty enthusiastic program you have got here. Like I 13 say, there is nobody that knows less about thermal-hydraulic 14 than I do, and now I think I ought to study up on this just () 15 so I can know what you are doing. It looks like fun. 16 MR. ELTAWILA: Thank you. 17 CHAIRMAN WALLIS: We can easily arrange that. 18 DR. POWERS: I know. I enroll in Dartmouth and 19 have to do these experiments and run computer codes -- gosh. 20 CHAIRMAN WALLIS: Farouk, you have done a great 21 job, but you have put us behind the time, although Dana is 22 here. We get very efficient if we go too late. I don't 23 think'we ought to~ finish later than 6 o' clock if we have to. 24 I am looking at tomorrow. We actually don't have 25 to finish until Noon. O
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l 226 1 1 MR. ELTAWILA: We actually have less material ) 2 tomorrow. [U) 3 CHAIRMAN WALLIS: If Jennifer will actually take 4 two hours. If she does not, we might get on to John 5 Mahaffy. Otherwise, we may put him on first thing tomorrow 6 morning. 7 MR. ELTAWILA: There is a short presentation by 8 Chris Boyd, if we have half-an-hour and we can adjust the 9 agenda to talk about CFD quickly. 10 CHAIRMAN WALLIS: Yes, and maybe boron mixing we 11 can do very quickly. 12 MR. ELTAWILA: There is no boron mixing, no 13 presentation on that. 14 CHAIRMAN WALLIS: So if we break now, can we break CT 15 for 10 minutes now and come back at 3:25? ( ,/ 16 MR. ELTAWILA: Thank you. 17 CHAIRMAN WALLIS: And maybe Dr. Uhle can get us 18 ahead a bit in time -- if we don' t interrupt too much. 19 DR. KRESS: If you don't ask any questions. 20 (Recess.] 21 CHAIRMAN WALLIS: We'll now come back into 22 session. We have a presentation from Dr. Jennifer Uhle, 23 which we are looking forward to very much. So is she. 24 MS. UHLE: I am just briefly going to talk about 25 NRC thermal-hydraulic activities. ANN RILEY & ASSOCIATES, LTD. .[\_/ } Court Reporters 1025 Ccnnecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 1
p l i # 227 1 This is going to cover the following items, but I 2 can skip over some things that Farouk went over in more 3 detail than I originally thought.
"4 I will go over the code consolidation. I think 5 you have heard a lot about the background and the goal so 6 maybe I will skip over that a little bit.
7 I will briefly talk about what is gc, M on in 8 reactor physics, what we have done to recover the stability 9 capability. 10 I am going to talk about the SQA and the 11 configuration control. I believe Professor Schrock was 12 interested in finding out the documentation. 13 I will talk a little bit about DA, mention what we 14 are doing right now with RELAP5, separate effects and model O (j 15 improvements, and then finally just summarize. 16 I know this is not new news to you. Just briefly 17 to summarize -- we have currently four thermal-hydraulics 18 codes and they include for the PWR we have RELAP5, TRAC-P 19 for the large break LOCA and for BWR we have the same 20 situation where we have RAMONA gave us a 3-D kinetics l 21 capability and it was also used for stability analysis, and j 22 then the LOCAs and transients were assessed or were run with 23 TRAC-B. 24 We are currently consolidating these capabilities 25 into one code. It is originally estimated it was a five-
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7 to h 228 1 year program but this may not be true, depending on budget () 2 and staffing situations. However, we are moving forward and 3 we are currently consolidating the code. We want to do this 4 mostly so that we only have one code to worry about. 5 There are identified deficiencies in the codes, no 6 we would like to only make improvements to one code instead 7 of the four codes and also there is not a lot of expertise 8 in-house. We are trying to move that in-house. However, if 9 we have four codes, we have to distribute that expertise 10 over four codes. It is much better and develops a 11 synergistic environment if everybody is focusing on one 12 code, so that is a bit of the background. 13 CHAIRMAN WALLIS: If you are going to keep RELAP5 14 until the end of the transition period -- 15 MS UHLE: Yes. That is the last to be 16 consolidated. 17 CHAIRMAN WALLIS: -- it would be useful to compare 18 it with your consolidated code, whatever it is called. 19 MS. UHLE: Yes. 20 CHAIRMAN WALLIS: TRAC-M -- 21 MS. UHLE: And we will do that -- 22 CHAIRMAN WALLIS: If there are lots of differences 23 we might worry about throwing it away. 24 MS. UHLE: Right. Well, as part of the 25 consolidation as I will go over with the example of the
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229 1 TRAC-B consolidation, as we are focusing on the identified () 2 capabilities of one particular code, we will run the 3 consolidated code at that point for those cases that the 4 original, you know, the one that we are trying to 5 consolidate was used for and we'll note the deficiencies and 6 we will systematically improve -- incorporate what we need . 7 to incorporate from the other code to make the consolidated . 8 code applicable to run those transients that the original 9 code was designed to do. 10 At this point in time we have TRAC-B and the 11 RAMONA capabilities just about consolidated so they are in 12 maintenance mode at the moment and aren't requiring any 13 funding in Fiscal Year 2000, but I will go over that. 14 DR. SCHROCK: What about TRAC-P? ( 15 MS. UHLE: What? 16 DR. SCHROCK: What about TRAC-P? 17 MS. UHLE: Well, TRAC-P is also at NRR in sort of 18 a frozen mode in TRAC-M. We have modified TRAC-P. We 19 modularized it and modernized it, so that is the current l 20 basis, but TRAC-P is over at NRR right now as a frozen code. l l 21 I will show you. It will make more sense. 22 I prettyfmuch went over this, but the existence of 23 the four codes certainly dilutes the NRC resources as well 24 as: reduces how much expertise can be developed in-house, so 25 we are consolidating to get rid of this problem and also we O ANN RILEY & ASSOCIATES, LTD. k_s Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 84P-0034
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230 1 are going to ensure that we recover all code capabilities, f,.s) 2 Concurrently improvements will be developed and 3 merged with the consolidated code throughout the effort. 4 Mostly at this point those have centered on the architecture 5 changes and some numerics changes and we have been working 6 on developing a graphical user interface and then taking 7 some test data to hopefully develop better physical models 8 in some particular cases. 9 At the same time we are also working -- or 10 Professor Mahaffy has worked on developing an external 11 component and he will be presenting that shortly after my 12 presentation, and this will give the ability to link TRAC-M i 13 to other codes and other simplified models. 14 At this time we are incorporating the TRAC-B () 15 capabilities. We are developing TRAC-M so that when we are 16 incorporating these new capabilities they go in easier and 17 we are also taking test data so that we can develop some of 18 these physical models in a more timely fashion once the 19 functionality has been consolidated. 20 This I think is going to explain the TRAC-M idea
.1 2 and so TRAC-P is serving as the basis of the consolidation.
22 The reason for this was, one, they had a 3-D vessel already. 23 Its particular architecture lended itself to be more easily 24 modularized in a sense it was already somewhat modular, more 25 so than, say, RELAP, and it had a network solver which was O ANN RILEY & ."SSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 1
I l f I l i 8 l 231 1
'l more extendable.
() 2 3 We modernized this version of TRAC-P and now we l call that TRAC-M just for the sake of calling it TRAC-M. 4 The goal of the modernization was, first, we 5 converted it into FORTRAN-90. We got rid of the container 6 array. The container array was very difficult to read - I 7 through the coding and understand what was going on. You 8 used a lot of pointers and now we have what is called i i 9 derived types in FORTRAN-90, so for instance if you want to 10 get the void fraction in a pipe you know the component 11 number of this pipe that's a one-dimensional component and 12 so it would be the derived type of alpha, of this particular l l 13 cell. That is much easier to read. People know what.it is. l l 14 It gets rid of a lot of the readability issues and also the j () 15 maintainability issues. It improves those. 16 That was done to facilitate consolidation. 17 We've also improved the portability of the code. 18 It now runs on all of these platforms that I have listed. 19 Again, the maintainability has been improved, the 20 readability has been improved, and the extendibility has 21 been improved. This came about because of some numerics 22 work that I'll explain later, and also for the sense that 23 it's much easier to develop in the code now that you can 24 actually read it and understand what's going on. 25 We also benefited from the Naval Reactor program l N_/ f) ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
3 232 1 that criginally started this modernization effort to put the 2- code into FORTRAN 90. 3 MR. BOEENERT: They gave you information? 4 MS. UHLE: No, they did some of the modernization. 5 MR. BOEHNERT: They did it? 6 MS. UHLE: Yes, they -- 7 MR. BOEHNERT: Oh, they paid you to do it.
- 8. MS. UHLE: No, they paid for it. They did the 1D 9 hydraulic components, they did the heat structures, and they 10 did the control system.
11: MR. BOEENERT: I'm just surprised they -- 12 MS. UHLE: NRC paid for the 3D hydraulic vessel. l 13 MR. BOEHNERT: I'm just surprised they gave it to 14 you.
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I 15 MS. UHLE: Oh, right, through LANL. g_ 16 MR. BOEENERT: Yes. Okay. 17 MS. UHLE: See, it's at LANL, so -- and Naval 18 Reactor interacts with LANL. We used the same code. They 19 did some of the modernization, and we did the rest. 20 MR. BOEHNERT: Well, it's just a comment, but I 21 mean, my experience with them is that they don't give 22 anybody anything. You know, they usually keep everything, 23 they classify it -- 24 MS, UHLE: Well, they tell you afterwards. 25 MR. BOEHNERT: Yes. But anyway -- okay, well,
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I 233 1 that's good, that's good. () 2 MS. UHLE: All right. 3 MR. BOEHNERT: That's a surprise. 4 MS. UHLE: On this modernization effort, we mostly 5 relied on null testing to make sure that we weren't changing I 6 the code. In other words, we were changing its 7 architecture, we were, you know, changing essentially the 8 coding language, and so we were expecting null results, and 9 made sure that we were getting null results. So we had the ) 10 same code, it just looked a whole lot different. 11 DR. SCHROCK: Does it have any impact on its J 12 ability to run the problem without a lot of nursing? 13- MS. UHLE: No, because we weren't really 14 changing -- we were just changing what it looked like. We , k_) 15 weren't changing any of the what do you want to call -- go 16 ahead, John. 17 MR. MAHAFFY: John Mahaffy. If I could interject 18 something here, there was one impact. Being somebody who 19 went through a lot of this effort, when you're doing this 20 so-called null testing, what you're doing is you're running 21 an old code and a new code, and the results compare very 22 accurately on a computer, you know you'd better get , 23 something that's last bit or know why. And often you would 24 implement an algorithm in a slightly different way or take 25- large blocks of code and clean them up, and you find yeu ,O ANN RILEY & ASSOCIATES, LTD. \/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 I (202) 842-0034 j .
I 234 1 don't get exactly match, and you ask yourself why, and lo
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( 2 and behold you find an error that's been in the code for 20 1 u 3 years, and you fix it. And there are a large number of ; l 4 those errors that have been fixed, and to that extent this- l 5 test procedure has improved the robustness of the code, j 6 DR. SCHROCK: Do you have QA procedures now that 7 will hopefully avoid that kind of error? j 8 MS. UHLE: I just wanted to sort of separate that, 9 because I do have something on bug fixes, but the main focus 10 of, you know, modernizing the code from the FORTRAN -- the 11 language standpoint was to improve the readability, and it 12 was going through the same calculation, in a sense, but it 13 just looked different. But there were bugs that were fixed 14 along the way. I 15 Okay. So again the modernization activities. We 16 put in the FORTRAN 90 language. You know, I do note some 17 things next to it, but for the sake of time I'll skip over 18 them. 19 On modularity -- we use the word " modular" a lot. 20 I'm going to try to define it a little bit better. I've 21 done this in the past, but I'll just do it again to brief 22 everybody. By high-level functional modularity, it means 23 that subroutines -- a set of subroutines collectively do one 24 function, and you can see this as an example of current work 25 that we're doing is separating the input processor. There's [ ANN RILEY & ASSOCIATES, LTD. b- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
4 235 1 a lot of subroutines that essentially read the input deck. 2 So somebody who wants to look at how the calculation is 3 progressing doesn't really need to know how the input deck 4 is read. So we're trying to separate that out a little bit 5 so that, you know, this particular functio:, is done with 6 these well-defined set of subroutines, whereas the sort of 7 computational engine handles the actual computation. 8 This will also facilitate coupling to the GUI. So 9 that was also why we were doing this. John Mahaffy did some 10 work on separating the solver from building of the matrix. 11 In the past the code was building terms that would -- 12 essentially the terms in the finite volume equations, but 13 would also start to solve them at the same time. So you 14 wouldn't have this matrix built. So this was replaced by 15 having subroutines simply build the terms in the matrix, and 16 then another set of subroutines to solve them. 17 Because we did this, we replaced or we added 18 another solver very quickly in very few -- I think it was a 19 few staff months. A grad student at Purdue University.under 20 Tom Downer put in a new solver. And for the case of the 21 AP600 large break LOCA, we found a speed increase of 25 22 percent. But this modularization allowed us to do this 23 quickly. So I know I don't want to underestimate how 24 important modularizing the code is. It allows you to i 25 certainly read through the code much easier. It allows you ANN RILEY & ASSOCIATES, LTD, N Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
236 ; 1 1 to focus in areas of the code that you want to focus on and N [V t 2 not have to be confused by other functions that are being 3 done at the same time. And it allows you to replace say 1 4 models or we get in a solver much more easily. 5 Another case of low-level functional modularity, 6 this means one subroutine performs one function. And in 7 this case what we did was we separated the physical models, 8 evaluating the physical models, things like interfacial drag 9 or' determining what the flow regime is. We separated the 10 physical models from the evaluation of terms in the mom'ntum 11 equation. Again, this also allows us to be able to go back j l 12 f.nto the code and modify perhaps some of the physical models j 13 later in the process, because it's separated from the 14 solution, or, you know, the setting up of the momentum IO g 15 equation.
- 16. This was done in house by an NRC member -- or 17 staff member -- and again, this was done by John. This is 18 being done at Los Alamos.
19 CHAIRMAN WALLIS: Did you find that you stuck with l
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20 the same sort of whatever you call them? I mean, j 21 nomenclature in the code? Did you have to redefine a lot of 22 things for the improvement? 23 MS. UHLE: Well, the FORTRAN 90 conversion, the 24 nomenclature changed dramatically. 25 CHAIRMAN WALLIS: Changed a lot. ANN RILEY & ASSOCIATES, LTD. s/ Court Reporters j
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I i 237 l 1 MS. UHLE: Right. Some of these -- my particular () 2 case, this right here, the nomenclature stayed the same, 3 because it was'at a very low lovel in the code, so the names 4 were pretty -- 5 CHAIRMAN WALLIS: So they would be recognizable to 6 the old users?
'7 MS. UHLE: Yes. I don't know about -- John was an 8 old user.
9 MR. MAHAFFY: Yes. 10 MS. UHLE: You may want to comment on that. 11 MR. MAHAFFY: Yes. John Mahaffy again. The 1 12 interesting thing here is that for an old user, in some i 13 sense the nomenclature didn't change, because it became l l 14 simpler. It's hard to convey to you the strangeness of the j e'^8 ! ( ,/ 15' code as it existed before modernization. It's related to 16 ancient and venerable computers that are long since extinct, 17 memory requirements, abilities of older versions of FORTRAN,I 18 and what happened was-that as we created new names for 19 subroutines and arrays, they were simpler in scope, more 20 meaningful to somebody who understands thermal-hydraulics. 21 A student who has some basic knowledge of thermal-hydraulics 22 two-phase flow can go in there and understand right away 23 where the void fraction is, the densities, the internal 24 energies, enthalpies, and be able to access them and put in 25 models or remove models fairly quickly,
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238 l 1 MS. UHLE: Further modernization activities is
/ 'T 2 under the heading of data communication. We essentially O
i 3 have different hydraulic components. We have a vessel, we 4 have a pipe, we have a valve, and they have to interact 5 together. And so how this data is passed between the 6 components was improved, and I'm calling this the hydro-to-7 hydro communication procedure. l 8 We also have heat structures, and the heat 9 structure is talking to a hydraulic component, and to get 10 the heat transfer coefficient, the heat structure needs to 11 know what the value of the void fraction is, what the liquid I 12 velocity is, things of that nature. And again through the 13 same say philosophy, this communication was also improved, ) 1 14 as well as the improvements in the control system. (A) 15 The way that this was done is that it was up front 16 during -- when you first read in the input deck, you 17 initialize how all these components are going to be talking 18 to each other, and it's set up upon initialization, and then 19 it's just a simple call to one subroutine to pass this 20 information. Whereas in the past it was in low-level 21 subroutines, some pointers were set aside to go get this 22 information, it was much more confusing. It's a much , ,, 23 cleaner way to do things. 24 CHAIRMAN WALLIS: The whole solution procedure is 25 based on a lot of simultaneous equations, and you go forward
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l l 239 1 in time steps. When you go forward in a time step, is there () 2 some sort of iteration, or do you invert a lot of matrices, l 3 or how do you actually solve all these things? l 4 MR. MAHAFFY: John Mahaffy again. I can go into 5 that in a little more detail later on, but at the core of 6 it, what happens is you can think of your finite difference 7 implementation of your two-fluid model. It becomes a set of 8 nonlinear equations in your fundamental variables, as you 9 know, and what's done in TRAC-M now is that during a time 10 step,-one time step in your finite difference model, finite l 11 volume model, however you want to do it, you've got a set of 12 nonlinear equations you solve in a new commuteration. Now 13 if you get -- that's the basic semi-implicit step. Somebody 14 talked about implementing a semi-implicit method. TRAC-M () 15 has sets methodology which adds some corrector steps to that 16 to stabilize the numerical method, and those are just simple 17 one-shot linear equations. So you've got an iterative 38 solution at the core of which are a set of matrices. It's 19 just a new commuteration. 20 CHAIRMAN WALLIS: - It's very robust then. 21 MR. MAHAFFY: Generally it's -- l 22 MS. UHLE: We have documentation, too, if you wan'; 1 23 more information on that. 24 CHAIRMAN WALLIS: Well,'do you have some of the l 25 problems that happened with earlier codes where you go into l l ( ANN RILEY & ASSOCIATES, LTD. 1 k- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 , (202) 842-0034 l
r 1 240 1 boxes where you had to run very, very, very short time steps l (m e) 2 because of the numeric, which didn't make any sense 3 physically, because things weren't changing very much? 4 Physically things only happen over a minute, but you have to 5 run over a microsecond in order to get the code run, which 6 seems absurd. But simply because of the mathematics which 7 was forcing you to do it. - l 8 MR. MAHAFFY: This gets back to a robustness 9_ question that was raised earlier. In the TRAC way of doing 10- things, back to the dawn of time, getting through a i 11 difficult calculation, lowering a time step was not an ! 12 option. If the code goes into a mode where the time step 13 drops, that is diagnostic of a more fundamental problem. 14 And when we talk about improving the robustness of this f~ 15 code, we're talking about getting to the more fundamental 16 problem so that the time-step size comes up, and not only, 17 does it get through the calculation, but it gets through the 18 calculation faster. 19 Now we'll not kid you, there are probably still 20 some of those class of problems in the code that we have to 21 deal with over the course of the next year or so that will 22 help us further improve the run time. 23 MS, UHLE: Okay. Other modernization activities, 24 again, the external component, John will talk about that 25 later. Again I want to stress the importance, the code is O ANN RILEY & ASSOCIATES, LTD.
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241 1 more readable, the developer can focus on one section having [I 2 to know the entire code. This facilitates bug fixes, 3 facilitates addition of capabilities. 4 The efficiency of the consolidation was certainly 5 enhanced, because we had people working in this code, and 6 some of them had never seen the code before. And again I 7 want to stress to that, I had no experience in this code or 8 any two-fluid code, and it was only a few months before I 9 could go in the code and fix bugs and put in additional I 10 capabilities, and I -- based on my knowledge of what used to j l 11 be done, you know, I would have had to have been sitting I 12 next to somebody for six months or more to understand what 13 was going on in the code. 14 So this whole modernization, it's not an immediate
) 15 user benefit. It's a benefit in the sense that we can do 16 things faster, but it's not as -- what's the word? --
17 definable, and I can't show you the figure of merit to say 18 that yes, we've made progress, but, I mean, we really have, 19 because again it's not overly difficult to go in and 20 understand what's going on in the code. 21 DR. SCHROCK: Could I ask you a question -- 22 MS. UHLE: Sure. 23 DR. SCHROCK: About this data communication? What 24 did you find in TRAC-P for the heat transfer to the two-25 phase fluids? There was a time that like RELAPS it had this ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 I
242 1- fictitious direct heat transfer from the wall to the vapor,_ O t 2 despite the fact that the flow regime says that it's a 3 . wetted wall. 4 MS. UHLE: Oh, you mean the flux flooding issue? 5 DR. SCHROCK: Yes, right, exactly. 6 What was the status of TRAC-P on that? Had that 7 been corrected in the current version, or -- 8 MS. UHLE: Well, there's still -- I mean, the two-9 fluid model, you have two fluids -- 10 DR. SCHROCK: Well, that's not two-fluid modeling. 11 I mean, that's -- 12 MS UHLE: Yes, it is. You have two fluids and 13 you have a wall, and you don't necessarily -- the only thing 14 that you know is'the void fraction, the average void 15 fraction, and you have to, to the best of your ability, 16 figure out how much is touching the wall that's liquid, and 17 how much is touching the wall'that's vapor. So it's sort of 18 a -- it's just inherent in the two fluids. 19 DR. SCHROCK: No, what I'm saying to you is that 20 the code had calculated heat transfer directly to the vapor, ) 21 despite the fact _that the code had a flow regime map that 22 told.it that the wall is wet. Okay? 23 MS. UHLE: Oh, that the wall is wet. Okay. 24 DR. SCHROCK: And so -- 25' MS. UHLE: I haven't myself gotten into the b V ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
243 1 subroutine that is evaluating the heat transfer () 2 3 coefficients, the wall to heat -- you know, the wall to fluid heat transfer coefficients, so I don't know that 4 answer. Can I just say one thing? 5 DR. SCHROCK: It could permit vapor to become 6 superheated, which is ridiculous when it's being fed only by 7 evaporation from an interface. 8 MS, UHLE: John wants to say something. I 9 MR. MAHAFFY: .Yes, let me make a comment. I 10 believe that if you looked at the internals of that, you 11 would not be entirely satisfied. I am not. 12 However, it's not at the threshold of ridiculous. 13 I don't believe you'll find situations where you've, for 14 instance, got a film on a wall, where you get superheated A ( ,) 15 vapor. That much it will not do, but I believe you will l 16 find that it is moving heat directly to the vapor. , 17 DR. SCHROCK: I think the history of it was.that 18 the RELAP5 developers took that model directly from TRAC and 19 as implemented there at the time that they were 20 demonstrating their plant analyzer based on RELAP 5 to the 21 ACRS subcommittee in Idaho Falls, it failed. And the fellow 22 who had been a reactor operator,.you may know who I mean, 23 who was so knowledgeable about the plant performance and 24 understood RELAP5 also, oh, he says that's that god damn 25 code. And when we got into an explanation of what he meant l , (' D ANN RILEY & ASSOCIATES, LTD. +> , l \- / Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 1 Washington, D.C. 20036 ! (202) 842-0034 i l i L_ >
244 1 by that, it turned out that the vapor was being superheated, 2 and this was causing some difficulty in crashing the code, j 3 MR. MAHAFFY: If I show less concern about this 4 than you might think, part of it has to do with Farouk's 5 plans that he's already discussed. There's going to come a 6 point another year down the line or so where we're going to 7 be taking for instance the exact situations we're talking 8 about, and we're going to be running RELAP5 and TRAC head to 9 head, and we're going to be asking the question which one i 10 has the better physical model to analyze this situation. I 11 think the answer will be the newer upgrade RELAP5 model, in, 12 which case that will be embedded in the consolidated code, 13 and we'll move on. 14 DR. SCHROCK: Well, you see, the problem 15 realistically is that the physics are violated in order to 16 satisfy a necessity in getting on with making a computer 17 code which will run, and there are other such examples in 18 these codes, and that was called out as one of the things 19 that needed to be watched for as we entered into this new 20 development phase. And I'm just raising the issue again 21 because you can kid yourself into thinking that you can walk 22 around the physics by some simple thing that's going to 23 facilitate the numerical computation, but it'll come back to 24 bite later. 25 MR. MAHAFFY: Oh, I understand --
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245 1 DR. SCHROCK: And so I just wanted to caution l (m) 2 again. This one we've talked about a lot in the past, and 3 it ought to get fixed in this code as it moves along. I i 4 don't think this is one that we ought to look for again in ' 5 the documentation that violates the physics, when it's very ' 6 clear you've got annular flow, you've got liquid on the 7 wall, and you do a computation that says some of the energy l l 8 transferred from the wall goes directly to the vapor. I I 9 That's nonsense. ' 10 MR. MAHAFFY: It depends on how you do that. You 11 can -- speaking as a physicist, okay, I can make physical 12 approximations about the -- about a steady state existing in 13 the film, and skip a step, right? And say some of this I 14 energy in a time that's too small for me to measure has () 15 moved on through the film and out to the vapor. But that 16 aside, I've got a question for you? Do you believe that the 17 latest RELAPS model is still inadequate in that respect? 18 DR. SCHROCK: Yes. I 19 MR. MAHAFFY: Okay. I was not aware of that. I i 20 thought they had addressed that in the later stages of the ! I i 21 AP600, 22 CHAIRMAN WALLIS: Maybe you could work it out 23 together. 24 MR. MAHAFFY: Yes.
.25 CHAIRMAN WALLIS: That's an important thing.
i ANN RILEY & ASSOCIATES, LTD. [x - Court Reporters 1 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l l :
i I I ( 246 1 MS. UHLE: I just want to say we weren't ignoring
. () '2 that. It's just that this particular hydro to heat l 3. structure communication, we weren't figuring out how much l
4- heat' flux was going to the liquid. I'm just saying that the 5 way the code works is the heat structure is responsible for 6 . coming up with the heat transfer coefficient, and it needs 7 to know what the hydraulic component says the void fraction 8 .is. So, I mean, I don't want to say that we are ignoring 9 .any deficiency like that. This was just more of an l 10 ' architectural change, not a physical model. 11 Okay. So right now we're working on the BWR 12 models, and looking at some of the comments from some of the 13 ACRS members, I don't think I explained this very well, 14 we're not simply lumping TRAC-B and TRAC-B and renaming it
) 15 TRAC-M, okay? Because this would be essentially the same 1
16 size as the current suite of codes, and that wouldn't reduce 17 the maintainability or the development of user experience, 18 okay? So what we're doing is we're using the modeling l 19 philosophy that was used in TRAC-B to develop these-BWR 20 components from the components that are in TRAC-M. 21 To describe that I am going to be using the jet 22 pump. The jet pump work was done Birol Aktas from 23 Scientech. He is right behind you over there, so if I look 24 in that direction, you will know why. 25' In TRAC-B the jet. pump is based on a tee, okay? ANN RILEY & ASSOCIATES, LTD. Court Reporters
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I- 4 1 247 1 We did the same thing in TRAC-M, we based it on a tee. O j 2 TRAC-M has a tee, TRAC-B has a tee, so there is no point in 3 taking the TRAC-B tee and moving it into TRAC-M just for the 4 jet pump, so instead.Birol looked at how TRAC-B was 5 modelling the jet pump and moved only those things he needed 6 to over into TRAC-M to have the functionality of the jet 7 pump. 8 As it turned out in TRAC-B, to predict the 9 pressure rise into the mixing of the suction and the drive 10 line flows TRAC-B applied a negative form loss coefficient. 11 I know Professor Wallis is going to love this. 12 CHAIRMAN WALLIS: It can exist, but not in this i 13 space. ! 14 MS, UHLE: This was derived from a properly 15 formulated momentum source term. They did this to match an 16 analytical result which essentially was Bernoulli, and the 17 reason why they had to this was because TRAC-B source term 18 wasn't proper in the physical sense. What they had done to 19 make the code easier to solve, if you want to say, they had 20 neglected the side leg momentum flux contribution and 21 because of that when -- for just a normal tee. 22 They said oh, it's just not important in the 23 normal tee. I am going to neglect it. It will make the" 24 code easier or make the numerics easier to solve. However, i 25 when they came to the jet pump they realized, oh, well O (d ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 i (202) 842-0034
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T 248 1 that's how the whole jet pump functions. Without that, I (V) 2 can't have a jet pump, so what they did is that they 3 explicitly -- by " explicit" I mean old time values -- added 4 this source term contribution and they had to then apply 5 this negative form loss or what they did is they put in form 6 loss -- what you want to call an arrangement or -- 7 CHAIRMAN WALLIS: Fudge. 8 MS. UHLE: Okay, anyway they put in this fudge 9 factor to make the results -- or formulation, okay? They 10 put in this K-loss formulation which gave them the results, 11 but TRAC-M, the way TRAC-M models a tee is that it uses a 12 . properly formulated source term so we didn't have to add in 13 this K-loss term. 14 So one good thing about this is that this momentum
/~5 "g _) 15 flux is implicit in TRAC-M whereas it is explicit in TRAC-16 B. Therefore in TRAC-M we won't have this time step 17 limitation problem that they do in TRAC-B, but what I wanted 18 to show is that we are not, like I said, simply taking 19 everything in track B and moving it over. We are only 20 taking things that we need to take over, okay?
21 Another thing that had to be added for the jet 22 pump in both TRAC-B and TRAC-P or TRAC-M was the 21 irreversible losses and this is just due to the nature of 24 the problem. Thee is incomplete mixing of the high velocity 25 drive line flow and the low velocity suction flow, so those ( ) ANN RILEY & ASSOCIATES, LTD. , kl Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i
I ? 249 ( 1 had to be brought over into TRAC-M. l lp) 2 Then there was loss terms for the unique geometry > \_/ 3 of the drive line nozzle. Those had to be brought into 4 TRAC-M. 5 Now what is the jet pump component in TRAC-M? 6 Well, a user will specify a jet pump, but interior to TRAC-7 M standard tee subroutines are called to set up the flow 8 equations, because it is based on a tee. The only thing 9 that is modified is the additional loss terms of the jet 10 pump specific losses which include the geometry of the drive 11 line, the extra loss term for the geometry of the drive 12 line, and the irreversible losses due to the mixing. 13 So again the tte subroutines were just not simply 14 copied from TRAC-B because TRAC-M can already model a tee. (O _) 15 Only additional features required to model a jet pump were 16 moved to TRAC-M so this is how the consolidation has worked. 17 CHAIRMAN WALLIS: So if we looked at the momentum 18 equations, we would believe them? 19 MS. UHLE: I think it would depend on your mood. 20 (Laughter.) 21 MS. UHLE: No -- 22 DR. POWERS: The essential question is do you try 23 to resolve the vector components -- 24 MS. UHLE: No. No, we don't divide mass -- by 25 one-half going into the tee. They match Bernoulli. ANN RILEY & ASSOCIATES, LTD. [/)
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250 1 CHAIRMAN WALLIS: So forcing it to look a tee is a () 2 3 bit artificial. MS. UHLE: Well, it is a tee when the tee, when 4 the side leg is turned to the zero degree angle and you have 5 a momentum flux coming in and you have the pressure rise due 6 to the -- 7 CHAIRMAN WALLIS: If the tee -- model is 8 sophisticated enough, then it might reduce to the jet pump 9 as a special case. Is that what it does? 10 MS. UHLE: That is essentially what it does. 11 CHAIRMAN WALLIS: Okay, that's fine, so if we 12 examined it we would be happy? 13 ~ MS. UHLE: You would be happy. 14 CHAIRMAN WALLIS: You still have the strange. () 15 student idea that the grade depends on the mood of the 16 professor. 17 MS. UHLE: But it does. 1 18 CHAIRMAN WALLIS: The mood of the professor is 19 utterly irrelevant. i 20 MS. UHLE: No, I don't agree.
.21 (Laughter.)
22 CRAIRMAN WALLIS: The professor changes when he 23 sees the -- 24 MS UHLE: The bad attitude of the student. Okay. 25 I am just going to do the CHAN example again. [A- ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l
I i 251 1 In the TRAC-B plant model, a 1-D flow path over () 2 rods and a leak path to the bypass volume between the 3 channels and the vessel, that is what the CHAN component is 4 trying to model, so it is the one dimensional flow path 5 through the core and then it also has this leak path going 6 to the bypass volume. 7 TRAC-B uses a pipe to this one-dimensional flow' 8 path, so it has this vessel and it connects the pipe at the 9 bottom and the pipe at the top and says okay, this is really 10 how the flow is going over my fuel rods. 11 Then to do the bypass or to do the connection to 12 the bypass volume it just simply takes this flux of mass, 13 momentum, and energy and with old time values adds it into 14 the equation for that particular cell in the vessel, so this () 15 can result in oscillatory behavior because of this explicit 16 dependence. 17 To get around this, a decision was made that we 18 would make what is called a single junction component. We 19 wanted to have a pipe modeling the CHAN component, but we 20 wanted to be able to simply connect one cell of this pipe to 21 one cell of the vessel through a junction that doesn't have 22 any volume, and so this is what the single junction 23 component does, so this was a capability we added to TRAC-M 24 to provide us with the ability to have an implicit leak 25 path. ANN RILEY & ASSOCIATES, LTD. O' Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 J l
252 1 CHAIRMAN WALLIS: It has no volume. Does it have () 2 3 inertia? If it doesn't have any inertia, then it will respond equally rapidly for the slightest perturbation. 4 MS. UHLE: Well, you can explain it. 5 MR. MAHAFFY: A better way to think of it is the 6 single junction component is another way of adding -- you 7 are in a finite volume methodology. In a " normal" -- 8 quote -- pipe, it is a classic one-dimensional mesh. You 9 have got your volumes. You have got your cell edges at 10 which you evaluate momentum equations. The single junction 11 component allows you to install another cell edge on your 12 finite volume and so not only do I have my two edges in my 13 one-dimensional alignment but I can add another one, think 14 of it on the side, and it is a standard evaluational () 15 momentum equation including inertia.
- 16. MS. UHLE: Okay, so anyway this is implicit, so 17 this is an improvement that we decided was important to 18 make.
19 In the future this will also facilitate the RELAP5 20 conversion because RELAP5 has pipes but they don't have end 21 junctions and so for RELAPS deck you have pipes and then you 22 have a single junction that connects the two pipes. IN TRAC 23 we don't have that because pipes have end junctions, so this 24 will facilitate the conversion between RELAP5 and TRAC 25 modeling philosophy and will also allow us to model valves i ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036
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I l 253 1 and pumps with zero volume.
, 2 In other words, it is just sort of a -- well, in 3 the case of a pump the momentum source term for this 4 particular junction. RELAPS doesn't have the valves and the 5 pumps. They don't have volumes, whereas in TRAC-P they do, 6 for TRAC-M they do, so this will facilitate the RELAP5 7 conversion.
8 At this point in time we have consolidated all but I i 9 I would say two of the BWR components. I will show you the 10 list in a second. We have consolidated the functionality. i 11 In other words we can actually run a jet pump. We can run a 12 CHAN component. We can run the level tracking model, things 13 of this nature. However, we have to do further assessment 14 to make sure that the code is giving the proper value, so (j 15 what may happen and what will probably happen is we will 16 have to bring over some BWR specific constitutive models to 17 be used just for those BWR components, because if you 18 remember in my example here the CHAN is based on a pipe, so 19 the TRAC-M -- so when it does interfacial drag, it is going 20 to use the TRAC-M pipe interfacial drag model and 21 interfacial drag in a rod bundle and interfacial drag in a 22 pipe, you know, they are dramatically different, orders of 23 magnitude, so we know we are most likely going to have to 24 bring over some BWR specific or component specific models 25 over into the code.
~
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F T li 254 1 However, the code in TRAC-M will only use those
; 2 brought-over models only for the case when it is modeling a m
3 particular BWR component. 4 CHAIRMAN WALLIS: Maybe all we need to know is 5 that you are figuring out ways to make this code to do both 6 BWRs and PWRs and so you are adapting it as you have to for 7 BWRs. 8 MS. UHLE: Okay. 9 CHAIRMAN WALLIS: Is that all we need to know, 10 really, and that you have done most of it already? 11 MS. UHLE: I think you are getting bored. 12 CHAIRMAN WALLIS: No , I am just saying -- 13 MS. UHLE: Yes, yes, that is what we are doing. 14 CHAIRMAN WALLIS: I am not sure this committee is
) 15 capable of looking at all these details. l 16 MS. UHLE: Okay. All right, yes, that is what we 17 are doing.
18 CHAIRMAN WALLIS: If we do, then you are going to 19 have to -- 20 MS. UHLE: No , no, no -- that is what we are 21 doing. 22 CHAIRMAN WALLIS: -- allow for our criticism of 23 the details. 24 MS. UHLE: No, no, that's what we are doing 25 essentially and at this point in time to update you I will 4 ANN RILEY & ASSOCIATES, LTD. s' Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
255 1 go faster now. T 2 CHAIRMAN WALLIS: We have got to have faith that b-3 you are doing a good job. 4 MS, UHLE: All the red ones are completed. The 5 only ones that'have to be finished is the containment 6 component, but that will be late September, early October. 7 The input processing -- Birol is doing the input 8 processing -- and that should be done by mid-October. ) 9 The input processing is interesting in the sense 10 that we will be able to run a TRAC-B input deck with the 11 TRAC-M code. i 12 CHAIRMAN WALLIS: So by the end of the year you 13 will be able to run BWRs with your new code? 14 MS. UHLE: Right, and we are going to be running (n) 15 the BWRs to help us identify which BWR-specific constitutive 16 relationships have to go into TRAC-M, so that is what we are 17 going on to in our next phase. 18 CHAIRMAN WALLIS: Yes. 19 MS. UHLE: Then the last one is the separator 20 component. A Staff member will be doing that, and hopefully 21 that will be done mid-November. 22 CHAIRMAN WALLIS: There is no need for us to 23 review any details? 24 MS. UHLE: No. 25 MR. MAHAFFY: One comment. John Mahaffy. We are O, ANN RILEY & ASSOCIATES, LTD. \_ ,/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
256 1 in fact running BWR problems right now. It's Penn State's l'% ( ) 2 task for instance to do some BWR assessments. Scientech is 3 also. 4 CHAIRMAN WALLIS: So you can assure us that if we 5 did choose to look at the details, we wouldn't find grounds 6 for complaint? 7 MS. UHLE: Oh, I'm sure you could always -- 8 CHAIRMAN WALLIS: I don't want to get into a 9 situation where ACRS picks up problems in details. 10 MS. UHLE: I mean like right now you are going to 11 run the CHAN component that is going to be using interfacial 12 drag for a pipe. 13 CHAIRMAN WALLIS: Somebody is going to run it. 14 DR. KRESS: I do want to ask for detail on the () 15 previous slide. 16 MS. UHLE: Yes. 17 DR. KRESS: The one you haven't completed, I 18 presume what you are doing is taking thermal-hydraulic 19 models out of CONTAIN and -- 20 MS. UHLE: It is actually -- okay, it is actually 21 in TRAC-B. There is a containment hydraulic component in 22 the sense, and it is based on the CONTEMP code. 1 23 DR. KRESS: Yes, but now you are going basically 1 24 on CONTAIN models? 25 MS. UHLE: No. We are taking what is in TRAC-B. 3 [] \_/ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 ! (202) 842-0034 i i l
257 1 DR. KRESS: So CONTAIN is just -- () 2 3 of the -- MS. UHLE: Oh, I'm sorry. Sorry, that is the name 4 CHAIRMAN WALLIS: That is the name in other words. 5 It is not the CONTAIN code. 6 MS. UHLE: Sorry. I probably shouldn't have put 7 those up there, but if you wanted to do an input deck you 8 would say this is SEPD. SEPD is what, a separator 9 component? 10 -DR. KRESS: I understand that. Okay. 11 MS. UHLE: CONTAIN is a thing -- 12 CHAIRMAN WALLIS: The problem is there is a code 13 called CONTAIN. 14 MS. UHLE: Yes, I know, right. Sorry. () 15 DR. KRESS: That does lead to another question 16 because the thermal-hydraulics in CONTAIN are coupled -- and 17 here you are going to have a decoupled -- 18 MS. UHLE:
. That's nothing fancy --
19 DR. KRESS: -- thermal-hydraulics. 20 MS UHLE: Yes, really that is like ODES. 21 DR. KRESS: Yes. 22 'MS. UHLE: Very simple, solves mass, you know, 23 energy for the two fluids. 24 DR. KRESS: Yes, I understand that. I was 25 confused. I thought you were actually using CONTAIN there. [~N ANN RILEY & ASSOCIATES, LTD.
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258 1 MS. UHLE: No. Sorry.
) 2 DR. KRESS: Thank you. So the three-dimensional O
3 kinetics. We know that we had to come up with the three-4 dimensional kinetics capability because that was in RAMONA, 5 so what we did was utilized PARCS, which is a three-6 dimensional kinetics code developed at Purdue University and 7 we have coupled it using PVM to TRAC-M. It is an explicit 8 coupling so it is old time information. 9 DR. SCHROCK: What is the vintage of PARCS? I 10 don't know that code. 11 MS. UHLE: Vintage -- it's an A&M and NEM method. 12 It was developed at Purdue University over the last five 13 years. 14 DR. SCHROCK: It's a relatively new program. 15 MR. EBERT: Basically it is a derivative of -- it 16 has features that made it more attractive for this than 17 RAMONA. RAMONA is what they call a line and half code and 18 Mark's is a fully modernized nodal code with two groups, two 19 energy groups, so it is quite an improvement over RAMONA. 20 What we needed to preserve is the functionality of 21 the 3-D kinetics, which we do quite well with PARCS. 22 MS. UHLE: Another good thing about this is that 23 it allows, with RAMONA it had its own hydraulics. This 24 allows us to have one hydraulic model of the TRAC code, and 25 then all we are getting, you know, we send over the void [ } ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 h L_
259 1 fraction, the boron concentration, the temperatures, the I j 2 liquid, and we get back power from PARCS, so it is more 3 consistent in the sense that we don't have extra thermal-4 hydraulics models lying around. 5 One code does kinetics and one code that does the 6 hydraulics and gets the three-dimensional kinetics from 7 PARCS. 8 DR. SCHROCK: Well, you didn't have a coupling 9 between RAMONA and the old codes. 10 MS. UHLE: No, but RAMONA had its three-11 dimensional -- 12 DR. SCHROCK: It had its own, right. 13 MS. UHLE: It had its hydraulic model. 14 DR. SCHROCK: So it is not incorporating anything 15 there. 16 DR. POWERS: Sometime in the past they sent me the 17 analysis they had gone through in comparing PARCS, NESTLE 18 and some other codes. And why they picked it, obviously, it 19 was not a clean decision, there were lots of factors that 20 were considered in making the selection. But it seems like 21 it is a decent enough code for most of the problems they are 22 going to come into. 23 DR. SCHROCK: So, will you be faced with having to 24 compare RAMONA against TRAC-M then? 25 MS. UHLE: In the assessment phase, we will be ANN RILEY & ASSOCIATES, LTD. x_ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l I
260 1 running the TRAC coupled code. I can get into that in a ( 2 little bit, in another viewgraph here. But I just wanted -- , l 3 what was my last thing? Oh, well, at any rate, that is all l l 4 you really need to know. However, it is just that the codes 5 are separated, they are very decoupled -- I mean they are l 6 coupled through PVM, but I mean one code stands alone, one 1 7 code stands alone, so it facilitates -- I mean it is i 8 inherently modular. It is inherently coarse-grained,- 9 parallel, and it just makes it a lot easier to be able to 10 develop PARCS on its on for the MOX issues that are arising. 11 And it also allows you to develop the thermal-hydraulics on 12 its own without having to intermingle the two. Okay. 13 Then speaking of what has been improved in PARCS, 14 we have added -- PARCS was a three-dimensional kinetics () 15 model and now has the ability to collapse into 1D kinetics. ; l 16 It allows for pin power reconstruction. j i l 17 CHAIRMAN WALLIS: What does ID kinetics mean? 18 MS. UHLE: One-dimensional kinetics. You don't 19 have -- 20 CHAIRMAN WALLIS: How can you have that? 21 MS, UHLE: When can you have that? 22 CHAIRMAN WALLIS: How can you really have that in 23 reality? It.is a very gross model. 24 MS. UHLE: Well, I think model ask, when do you 25 really need three-dimensional kinetics? ANN RILEY & ASSOCIATES, LTD.
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261 1 CHAIRMAN WALLIS: Well, if you have got (v; 2 oscillations and things, 3 MR. EBERT: You can go to zero if you like. 4 MS. UHLE: Yeah, you can get axial oscillations, 5 but you don't get azimuthal oscillations. I mean but in the 6 case of like a steam line break or a turbine drip. 7 MR. EBERT: This is David Ebert again. The reason 8 we put in 1D kinetics capability in PARCS is because we want 9 to preserve the functionality of the kinetics with TRAC-B, 1 10 which TRAC-B has one-dimensional capability. So we wanted 11 to preserve that capability. 12 CHAIRMAN WALLIS: It is an option, it is not 13 really an improvement, it is just retaining an option that 14 is useful.
,m
() 15 MR. EBERT: 3D kinetics is, of course, the 16 ultimate, but we wanted to preserve the functionality so we 17 can do some comparisons of the results. 18 CHAIRMAN WALLIS: Sure. , l 19 DR. SCHROCK: What do you expect to learn from i 20 that comparison? 21 MR. EBERT: Actually, it is going to be very 22 interesting because we can learn, for instance, in stability 23 tests, we can learn what tne phenomena difference, physical 24 phenomena differences between modeling it in 1D and 3D. In 25 other words, we can separate the side issues in the [Dl ANN RILEY & ASSOCIATES, LTD. Court Reporters (._ 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 1 n . i
I h 262 1 oscillation from the top to bottom issues. So that will be s
) 2 quite interesting. And then we will also have the point w-3 kinetics capability, so we can analyze even a third aspect.
4 So we can separate out these physical components. 5 DR. SCHROCK: You have got two sort of distinct 6 approachas to getting the 1D kinetics, I guess. One is to 7 take a 3D kinetics model and manipulate it through 8 integration to get a 1D model. And so when you compare the 9 results of those two kinetics calculations, I am not sure 10 you will really be separating radial and longitudinal 11 physical effects in a very clear way. 12 MR. EBERT: Well, if these oscillations are a 13 complicated interaction between the kinetics and the 14 thermal-hydraulics, so they will give us insight. We may ,y ( ,) 15 not get the complete picture, but it will lead to some 16 insight. 17 DR. SCHROCK: Okay. 18 MS. UHLE: Okay. Again, we have added the pin 19 power reconstruction capability. These are potential things 20 that may be done based on user need. It is improving PARCS 21 to have four energy groups instead of two energy groups for 22 the MOX issues. And also for another MOX issue is to add a 23 semi-analytic transverse leakage capability. Currently in 24 the code yo'1 do have the ability to use ANM or NEM 25 methodology to do the transverse leakage. It is just it is ,~i ANN RILEY & ASSOCIATES, LTD. (-) Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 r <
i i 263 1 hard to take an ANM model and improve it, or to expand it to () 2 more than two groups. 3 CHAIRMAN WALLIS: Can't you just have I energy 4 groups and then the user specif3as how many and then fill in 5 the matrix or something? Why don't you have -- the energy 6 groups, the number you have is kind of arbitrary. The 7 method you use is the same, you just have to put in more 8 data if you have a lot of energy groups. Isn't that true? 9 MS. UHLE: Well, Dave can answer that. 10 CHAIRMAN WALLIS: Why don't you just have I energy 11 groups as an option? 12 MS. UHLE: Because it is like having sort of more I 13 than two fluid equations. 14 CHAIRMAN WALLIS: No, no, no. It is much simpler 15 than that. 16 MS, UHLE: No, I don't think so. 17 CHAIRMAN WALLIS: No, it is much simpler. l l 18 MR. EBERT: It is a possibility, but I think you ] 19 probably only need four, you probably need only four groups. , 1 20 I mean I can't imagine they would need more than that. , l 21 MS. UHLE: I mean if you generate all your cross-22 sections. 23 CHAIRMAN WALLIS: The computer is very easy, you 24 .just have to fill in the information you need to transfer it 25 from.all the things that go in the equations. h \/ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l
( , 1 264 3 1 MR. EBERT: Well, it would be ideal if you could () '2 3 put in I for anything. Birol found out that the fast reactors, of course, you need more than four energy groups. 4 CHAIRMAN WALLIS: It would. It might not be much ) 5 more work to put in I. Looking ahead. 6 MS. UHLE: Okay. Well, whatever. Okay. So, 7 anyway, so PARCS is inherently set up, or at least more set i 8 up than a lot of codes, to be able to do a semi-analytic l 9 where the lower energy groups are the NEM and the higher 10 energy groups are the ANM methodology. But that again will 11 come from a user need if necessary. 12 Okay. So, on the issue of stability, we 13 originally, it was thought that based on some work that was ; 1 14 done by Birol and Scott Lucas at Scientech, and also GE,
) 15 that in order to capture stability phenomena, you can't have ,
l 16 a very diffusive numeric scheme. So we put in the semi- l l 17 implicit methodology, or the semi-implicit scheme into the 18 code, because it is currently running, or the default, 19 numeric scheme is SETS, which is a nearly implicit type of 20 scheme. It is a little different, but John can get into in 21 more detail if you want. But it is more diffusive than, 22 say, the semi-implicit. 23 So you put in the semi-implicit, the scheme to 24 limit the numerical diffusion, and it was found that, 25 provided you pay attention to your nodalization, and the O ANN RILEY & ASSOCIATES, LTD. k~s/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l I
r 265 1 fact that the code does have upwind differencing, we can () 2 3 actually do stability phenomena. You can propagate a density wave instability and there is, you know, it doesn't 4 have -- doesn't numerical diffuse the result, so that this 5 phenomena was captured. 6 However, as Professor Schrock has pointed out, wo 7 are going to be ensuring that the 3D kinetics package atd 8 the hydraulics, again, using the semi-implicit method, will 9 predict plant behavior. And so in this fiscal year, we will 10 be running the Ringhals problem and the Peach Bottom turbine 11 trip. 12 CHAIRMAN WALLIS: Ringhals? 13 MS. UHLE: I don't have the accent, I guess. 14 Okay. So, on the SQA, I know I am jumping from topic to x 15 topic, but on the SQA issue, we followed software quality 16 assurance throughout the consolidation process. 17 DR. POWERS: Whose? 18 MS. UHLE: Ours. 19 DR. POWERS: Yours. And how do I compare yours to 20 something I am very familiar with? 21' MS. UHLE: I don't know what you are familiar 22 with, so that would be difficult for me to answer. 23 DR. POWERS: Two out of three. 24 MS. UHLE: All right. Can I explain what we did? 25 DR. POWERS: Two out of three commercial standards Ci ANN RILEY & ASSOCIATES, LTD. \ss/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 3 m
266 1 and DOE standard. h 2 MS. UHLE: Okay. Can I explain what we did and (x-Jl . 3 then you can point out what maybe we did wrong, or what we 4 did right? Okay. 5- In the past, the procedures for the developmental
- 6. assessment, the software quality assurance and the 7 documentation were primarily planned by the contractor.
8 Variations in these procedures often resulted, NRC didn't 9- have as much control over the process as perhaps it should 10 have. 11 CHAIRMAN WALLIS: The original TRAC didn't have l 12 any SQA. They just threw in whatever they wanted to throw 13 in, and you had to figure it out if you could. 14 MS. UHLE: Well, there are some manuals, Eo it is , f~' \ ( ,\ / 15 not at all lost. The code runs. But I agree, it had to be i 16 improved. 17 CHAIRMAN WALLIS: It was very difficult to figure 18 out. 19 MS. UHLE: Yeah. Okay. So it had to be improved. 20 And so we took effort to improve that. So what we currently 21 have is for the software, the documentation requirements, is 22 that first we have the requirements document. Essentially, 23 I am going to do -- what am I going to do? In other words, 1 24 I am going to be giving you a code update. And so what is ! 25- this update supposed to do? l l (~'\ ANN RILEY & ASSOCIATES, LTD. ( l' Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 j Washington, D.C. 20036 ; (202) 842-0034 c \
r 267 1 In the instance of, say, the JET pump, it had to () 2 run the transients that -- you know, have the JET pump run 3 over all the conditions that it ran in TRAC-B. It had to 4 collapse to the results of a tee. You know, blah, blah, l 5 blah. 6 So this, again, is just clearly defining what the 7 purpose of this particular code update was. Okay. A test 8 plan is also generated and it lists the plan tests and links 9 them back to the software requirements document. So, in i 10 other words, the test plan will say I am running this test. 11 This test is going to prove that requirement number 1 was 12 met. And it also lists the expected results. 13 Also, another document after the work has been 14 completed is the software design and implementation O ( ,/ 15 document. And it describes how the changes were made to the 16 code. In other words, I wanted to put in the JET pump model 17 what sub-routines did I have to modify, you know. Again, 18 how was -- were there any design decisions along the way 19 that I had to make? Why did I make it this way? Again, it 20 describes the whole implementation process as well as design 21 process. 22 And then, finally, a completion report, and it 23- contains results from the test plan and lists the files and 24 the materials needed to run the tests. Okay. 25 So these are the documents that we require. And [] \m/ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i i i
1 W 268 1 the way it works in the configuration control system is that ()/ 2 the configuration control is now in-house at NRC. Again, in 3 the past, the configuration control was handled at a 1 4 contractor. And, again, NRC didn't have as much control I I 5 over it as perhaps was needed. 6 So we have-taken the lead role in the 7 ~ configuration control. So what we currently have is a ; 1 8 central repository for the source code and all the software 9 quality assurance documents. This prevents the loss of the 10 source code and these documents. It helps NRC be on the 11 forefront for planning the development effort and making 12 sure they know what is going on at the multi-site 1 13 development process that we have entered into. 14 Development patches aren't accepted unless the SQA ()) 15 requirements are met. And I am the one that decides if they 16 are met or not, so I do make sure that the documents are l 17 there. And, also, I typically scan the updates and have a l 18 good _ idea of what sub-routines have changed, how they were 19 changed to make sure that, you know, it is going to work the 20 way it says it is going to work. 21 The way I do is I put it into a test version of 22 the code, I don't put it in the repository yet. I run the 23 code. I look at the test results, make sure that they match 24 what the test plan said it was going to do, and then I -- 25 what is called put it into the archive directory, which /O ANN RILEY & ASSOCIATES, LTD. \_) Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i i
269 1 essentially has all of the updates to the code, for every 1 es I (O ) 2 version that we have made. And this way, this code ! 3 repository, I can go back and ask for any version of the 4 code, and we have all the code versions listed, and simply 5 stated, what this version was made for, you know, if it was 6 the incorporation of the JET pump model, if it was the 7 incorporation of the level tracking or what-have-you. So it 8 is all at NRC and it is very easy to follow, and I think it 9 has really helped the development efficiency. ) 10 So what happens again is I, or whoever the code i 11 configuration person is -- Chester sometimes, okay -- l 12 creates, compiles and distributes the versions, okay. So, i 13 once I have decided, or once I have assured that the SQA 14 documents are there, I perform the merges and check that the f 15 patches have gone into the archive, the archival storage, I 16 should say.
- 17. We have a website set up for the development work.
18 Again, Birol was a help in setting this up. And it has 19 links to all the documents, all the code change summaries ! 20 and it lists, you know, what -- this is the version, here ! 21 are the documents. This is where you go to get the source 22 code and what did this update do, and it just gives a brief 23 description. And who was the developer that did it. So we 24 'have this on a website, again, so you can simply scan 25 through this website to see all the changes to the code. ANN RILEY & ASSOCIATES, LTD. (/) \- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i
m 270 1 And, again, it is all backed.up on tape every night, and it 2 is all in one location which, again, is much more efficient 3- than the development process had been in the past. 4 We also have a test directory with all the test
- 5. cases that have come in. For instance, when the JET pump 6 was submitted, Birol submitted the test cases that prove )
7 that the JET pump worked. It is also in a directory. I can I 8 access that from what is called the Auto-DA script. I l 9 simply type in, you know, test, using the CHAN -- or, sorry, 10 using the JET pump test cases, this particular version. It 11 -runs all the cases and it puts it in its own directory. I 12 can, you know, difference the versions, the results of all 13 the test programs. 14 CHAIRMAN WALLIS: Excuse me. When you said there 15 is a website, is this something which is accessible to 16 anybody here?
.17 MS. UHLE: No. You have to be on a list.
18- CHAIRMAN WALLIS: Oh. 19 MS. UHLE: I am not going to put you on that list. 20 I am sure you can see it if you would like to. 21 CHAIRMAN WALLIS: You have got me curious'about , 22 the details. Could I be put on the-website? I just read ~ ) 23 stuff and it is random access and see if'it made any sense 24- to me. s' 25 MS UHLE: Yeah, I guess. Yeah,'I mean it is O ANN RILEY & ASSOCIATES, LTD. 1 V Court Reporters i 1025 Connecticut Avenue, NW, Suite 1014 i Washington, D.C. 20036 (202) 842-0034 o i ' il 1
271 1 simple to put people on it. And it is simple system. n i 1 2 CHAIRMAN WALLIS: I wouldn't have any right to %.) 3 change anything, I wouldn't expect to. But I just am 4 curious to see how these things get done. 5- MS. UHLE: Yeah. Right. 6 CHAIRMAN WALLIS: It might be interesting. 7 MS, UHLE: Yeah, yeah. I mean it is interesting. 8 I mean you can come up and I can show you the repository, it 9 is pretty efficient. 10 MR. MAHAFFY: If I could interject a comment here. 11 In 25 years of code development, I have got to tell you that 12 this is the best organized code configuration control effort
.13 that I have seen. The website particularly has been very 14 well designed. We an operating an effort of distributed
() . 15 development. It has held things together very, very well. 16' it'is very easy for me to understand what somebody out in
- 17. Los Alamos or Purdue has been doing so I can adapt to it. I 18 have been very pleased with it.
19 You should do a round of applause for Birol. 20 And we have a few jokes on the left side, too. 21 CHAIRMAN WALLIS: Oh, no. 22 MS. UHLE: Yes. So, you know, you have to get j 23 around some of the jokes, but we'll have' to take your 24 character at your -- 25 [ Laughter.] 1 [D \ /- ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l It
272 1 DR. POWERS: Farouk, I definitely want to be put 'l
- 2 on that list.
d 3 MS. UHLE: Okay. 4 DR. POWERS: I've got a couple to add to your 5 collection. 6 MS. UHLE: Yes. Okay. I 7 Okay. Currently on the developmental assessment j 8 front, we know that we supposedly said we'd consolidated 9 these codes, but now we're entering into this developmental 10 assessment phase. So essentially what this means is that we 11 have all of the test matrices for TRAC-B, TRAC-P, and what 12 RAMONA was used for. 13 We are at this point putting this into one matrix, 14 but we're also doing this in a more organized fashion. O) (, 15 We've identified essentially the transients for the integral 16 effects test that the codes were responsible for running. 17 We supplemented -- we again started with the CSNI 18 matrix. It was easier in a sense because the CSNI group had 19 done a lot of work identifying what are good transients to 20 run, and also made a list of where this data was available. 21 We supplemented this with other transients, particularly 22 with AP600. We then identified separate-effects tests, 23 again used the CSNI as the starting point, 24 We determined the ranges of parameters using the 25 code calculations of full-scale test facilities and full-
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273 1 scale plants, and also scale test data. So we know the q(
, 2 ranges of conditions over which these particular models need 3 to operate.
4 DR. KRESS: Is that separate from the code?- It's 5 not built into the code? 6 MS. UHLE: No. No. It's its own matrix. 7 DR. KRESS: It's not like Bob Henry's dynamic 8 benchmarking. 9 MS. UHLE: No. No. No. 10 At this point we're just -- I said we're doing 11 this. This hasn't been complete, you know, altogether i l 12 completed at this point in time, but this is the method that 13- we're using to make this developmental assessment matrix. 14 From that we'll have -- it's a much more organized matrix.
.s I
15 We know what ranges of conditions we're trying to cover. We 16 also are making sure that we're not duplicating any of these 17 ranges, because again there has been some overlap in the 18 code-development work. 19 We are -- let me see -- oh, yes, okay, so at this
-20 point in time, what we currently have done is taken some of 21 the tests we know are TRAC-B specific and RAMONA-specific 22 and have identified them and have started work on building 23 the input decks as necessary to start to help identify which 24 of the BWR-specific relationships have to be brought over 25 into the TRAC code.
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274 1 Then we will run the' integral effects tests to 2 ( ) ensure that all these models work together. But we can't 3 sacrifice the accuracy of the code for the TRAC-P or the 4 TRAC-M, I want to say old TRAC-P, applications just because 5 we want the BWR applications to work well. So we have to 6 pay a lot of attention to the integral effects tests just as 7 much as the separate effects tests. 8 We have an Auto-DA script that helps us do these 9 runs. This Auto-DA script will just essentially allow you 10 to write in how many cases you want to run and what plots do 11 you want generated. It generates the plots for you 12 automatically so that you don't have to manually do this all l 13 the time. 14 We're also linking this Auto-DA script with a i
) 15 numerical ranking capability called ACAP -- automated code 16 assessment package. And what this is is this plotting 17 essentially.is comparing two lines to see how similar they 18 are or how different they are,.as the case may be.
19 So this was a problem back in the AP600 days when 20 we were trying to, you know, hold up two different curves 21 and say which one matches the other one better, and it 22 wasn't the most ideal situation, so we had the idea of 23 generating results from numerical techniques, and so they'll 24 be on the order of 10 or 15 numerical techniques that will 25 compare how close two lines are, and will give a numerical O ANN RILEY & ASSOCIATES, LTD. (_ / Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
I 275 1 answer. And we can compare the results of these assessment () 2 cases over, you know, as the code develops. And it will 3 also allow us to say okay, which match the data better, 4 TRAC-B or TRAC-M with the BWR components. Well, we can have I 5 this numerical technique that will take away some of the ' 6 subjectivity in this assessment. 7 CHAIRMAN WALLIS: This is a way, it's giving a 8 measure of uncertainty, too. 9 MS. UHLE: It can be used to help you -- 10 CHAIRMAN WALLIS: Yes. 11 MS. UHLE: Do uncertainty, because it's telling 1 12 you how different the lines are -- 13 CHAIRMAN WALLIS: Right. 14 MS. UHLE: And that's hard to do if it's not 15 just -- 16 CHAIRMAN WALLIS: So maybe this is -- l 17 MS. UHLE: One point. I 18 CHAIRMAN WALLIS: Basis of putting some 19 uncertainty into the code. 20 MS. UHLE: Yes, and another thing, too, on the 21 uncertainty is'that there's a lot of CAMP members that have 22 been working on. uncertainty techniques, and they have been 23 using RELAP mostly, but I think over time a pretty efficient 24 methodology will arise, and some of the processes that were 25 ~ described in the last CAMP meeting involved, you know, D ANN RILEY & ASSOCIATES, LTD. [O Court Reporters 1025. Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 - A' .x
276 1 comparing two lines and saying how similar they are. / l,
,- 2 DR. KRESS: Is that something like a regression 3 analysis?
4 MS. UHLE: Some of those techniques, there are 5 different mathematical things. There's a wavelet, there's 6 a-- 7 DR. KRESS: Oh, you're using wavelets. 8 MS. UHLE: In some of the cases; yes. John can -- 9 MR. MAHAFFY: I designed that, again, if I didn't 10 actually implement -- ACAP is really two things in one. It 11 is an exploratory tool to test -- there are about 20 to 30 12 different quantitative comparison methods that you can apply 13 to sets of data. And some are more relevant to different 14 sets of data than others. So that you get a two-step (^ r ( ,) 15 process. 16 You want to look at the data you have for a given 17 test and experiment a little bit to decide which method is 18 best for you. And then ACAP will run in a batch mode in 19 association with that Auto-DA tool where you tell it all 20 right, for this data use this method and give me a 21 quantitative -- a number that tells me how good my match is. 22 And now I can -- to the extent I have faith in that number, 23 I can now run different versions of the code to see if my 24 results improve or not. I can compare RELAPS to TRAC-M, 25 that sort of thing. And from his standpoint I can go in
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277 1 there and I can perturb a model. If I know the -- ( ) 2 DR. KRESS: To see how much effect it has. 3 MR. MAHAFFY: Yes. If I know there's a certain 4 amount of uncertainty in my wall friction correlation, I can 5 perturb my wall friction correlation by a certain amount -- 6 DR. KRESS: To see what it does to -- 7 MR. MAHAFFY: And see how that changes the output 8 of some key parameter. 9 DR. KRESS: It's a good idea. How do you use 10 wavelets in that? That's a way to -- it's a way to get a 11 more or less empirical equation for a set of data, I 12 presume. 13 MR. MAHAFFY: Right now -- 14 DR. KRESS: Like J core EA analysis. ! 19 MR. MAHAFFY: That's right. There are two things 16 you can do with the wavelets right now. You can actually j 17 .look at the-sort of spectral distributions from two 18 different items and just visually compare. It's got a 19 ' fairly good set of graphics. That's an aside. The other 20 thing is you can define an acceptability criteria so that if 21: your amplitudes across your full spectrum match within a 22 certain level it declares that you've achieved an acceptable 23 match. 24 DR. KRESS: That's a good idea. I like that. I'd ' 25 like to see that. O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 n 1.
i 278 1 MS. UHLE: We've had a lot of interest from even
; 2 Naval Reactors and a lot of CAMP members that are interested 3 in getting the use of this tool. So -- oh, okay, we're 4 back. I 5 This is -- now that we said we're doing this 6 consolidation right now, but we are making some improvements 7 to the code at the same time in the areas of architecture 8 and modernization and some of the numerics work, but we 9 still have RELAP5 as the main workhorse. Most people do use 10 RELAP5. So we made the statement that the RELAPS 11 capabilities will be incorporated upon the completion of the 12 BWR work, but there is currently no activity. We're going 13 to wait to see how the consolidation goes. Right now we 14 have the functionality.
m
/ 15 Now the next step is the developmental assessment 16 to identify the BWR-specific models, and we just want to see 17 how this whole thing is working as far as capturing the 18 capabilities of both TRAC-M, TRAC-B, and RAMONA. So at this 19 time we're not -- there is no real dedicated effort to start l l
20 the RELAP5 consolidation. However, we have done a few 21 things along the -- or some decisions were made along the 1 l 22 way of the consolidation that would facilitate the RELAP5 l 23 consolidation if that is the path that we, you know, we end I 24 up going down. l l 25 And this involves a single-junction component. l 1 l 1
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279 1 The GUI will provide deck conversion. And the external [) v 2 component by John Mahaffy was originally the sort of proof 3 r- principle is going to be shown with a simplified 4 accumulator model. And it was chosen to have the 5 accumulator model of RELAP5. 6 In TRAC-M right now to model the accumulator, you 7 take the pipe and you set a flag, and you set it equal to 1, 8 and that says that I want a very high or very low 9 interfacial drag in this pipe, and it allows the faces to 10 separate and, you know, that's essentially the accumulator 11 component. Now, however, that's -- you know, the physics of 12 the accumulator component is mostly just perfect gas 13 expansion, so that's the RELAP5 approach. And so to make l 14 that work inside of sets is, you know, more difficult than () 15 it needs to be, so it was the idea of having external 16 component do its own sort of numerical scheme and link into 17 the code, and John is proving, you know, that philosophy 18 with the external component. 19 DR. KRESS: That's the way to get different note 20 sizes and time steps into something that's harder to model? 21 MS. UHLE: He has quite a long presentation. 22 DR. KRESS: Oh, okay. 23 MS. UHLE: But at the same time, because RELAP5 is 24 the workhorse and. CAMP does support RELAP5 as well, there 25- have been some user-requested improvements made to the code t ANN RILEY & ASSOCIATES, LTD. ( Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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1 280 1 during this consolidation process. The 3-D kinetics has I~ \ 2 been coupled in the same fashion as we had with TRAC-M with \s / l 3 the PARCS coupling with PVM. The mass error has been j 4 improved. This was found to be mostly caused by equation 5 estate problems.when you're extrapolating into the 6' superheated liquid and the subcooled vapor regions. 7 The time step dependency and the platform 8 dependency, these two issues are still high on the priority
]
9 list to be fixed. Those are not currently being worked on i 10 in the sense that they're fixing the mass error and a few of I 11 the oscillation problems, and then they're going to reassess 12 the time step and platform dependency to see if some of 13 these' changes have improved that. But there are still some 14 outstanding issues in RELAP5 to takm of. () 15 DR. KRESS: What exactly do you mean by platform 16 dependency? 17 MS. UHLE: When you take the same input deck and 18 you take the same version of the code and you run it on an 19 SGI, which is a UNIX machine., and you run it on another one. 20 DR. KRESS: Okay. I understand. 21 MS. UHLE: Okay. So just with the time line to 22 put this all in perspective,'here we are, the modernization 23 and some of the modularization started back here in '98 or 24 finished back in '98. The TRAC-B component models have gone 25 in, and they're just about finished now, but for operating O ANN RILEY & ASSOCIATES, LTD. k . l-m Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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281
-1 plan and, you know, and some of the different schedules, the r" l
[%) 2 due:date was Decenber or January of 2000, but they're like I 3 said mostly in at this point.
]
4 The 3-D kinetics has been incorporated. The TRAC-5 B physical model is based on the DA work. This will be
-6 worked on at the end of, you know, beginning fiscal year 7 2000. And it's hard to say exactly how long is this going 3 8 to take, because we don't really know necessarily off the 9 top of our heads what has to go in. You have some idea, 10 things like interface drag, as I gave the example, the CHAN, 11 choking flow models are different.
12 You know, some of the models are different. So 13 those are ones that we chose some of the developmental 14 assessment cases to focus on. But again, that's why it's O(_,f 15 dashed, because I mean it could take a month and it could 16 take longer. We'll see. 17 And then we'll take a break and make sure that 18 we're happy with the results of this consolidated code at 19 this point in time. And if all looks well and all goes 20 well, then we'll start to be incorporating the physical 21 models of RELAP5. 22 I want to say the physical models of RELAP5, 23 because there's no functional -- there's no functionality 24 that has to be incorporated. It's all physical models. 25 It's not like they have a CMT component that we have to
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282 1 bring over or anything like that, and, you know, they () 2 3 don't -- the code at this date doesn't have anything like that. The only model or only capability that would have had 4 to have been brought over would have been the accumulator 5 model, but we've already brought that over anyway through 6 the external component. 7 So again this will mostly be relying on DA, and 8 that's where we'll run the consolidated DA matrix in a 9 systematic fashion and identify which models are better in 10 RELAP than they are in TRAC or vice versa to come up with a 11 final consolidated code. 12 I can skip on this stuff, or I can continue. 13 DR. KRESS: Is that being done at Maryland, 14 University of Maryland? O( ,f 15 MS. UHLE: Which? 16 DR. KRESS: This interfacial air. 17 MS, UHLE: Oh, this interfacial air transfer, this 18 is being done at Purdue. 19 DR. KRESS: Purdue. 20 MS. UHLE: But Professor Wallis, in some of his 21 comments, asked for a bit more information on.this 22 particular one. What I am getting -- 23 CHAIRMAN WALLIS: I was interested in seeing if 24 you had any results from it. 25 MS. UHLE: Yeah, I do, i ANN RILEY & ASSOCIATES, LTD. k Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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283 1 CHAIRMAN WALLIS: I think I understand what it is (n) 2 trying to do. Does it work? 3 MS. UHLE: Yeah. 4 CHAIRMAN WALLIS: Do you have some before and 5 after tests, or something that shows it works? 6 MS. UHLE: Yeah. Yeah. What I am getting into 7 here is just we know we have some modeling deficiencies in 8 the code, and so we had to start taking test data, because 9 sometimes it takes a few years to get the adequate database-10- to develop a model to put it into the code. So the 11 interfacial area was an example of one of, you know, these 12 potential models. 13 Currently in the codes it is a static flow regime 14 map where you have your mass flux and you have your void (3 15 (_,/ fraction, and you figure out what flow regime you are. 16 Based on this flow regime, you have an idea of what that 17 looks like, and you take your void fraction and you figure 18 out how it would be configured, and you come up with an 19 interfacial area, f 20 The interfacial area is actually used in the 21 2-fluid model because it is the interaction terms, you know, 22 the interfacial drag is the area, the interfacial area times 23 the drag coefficient, per se, times the relative velocity 24 squared. So you, you know, the 2-fluid model inherently 1 25 wants an interfacial area, and, in fact, in the codes we do l ( ANN RILEY & ASSOCIATES, LTD. \> Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (2a2) 842-0034 i s
284 1 calculate one. _.I 2 I am showing right here, this is data that was 3 taken at Purdue and it was co-current bubbly flow. 4 CHAIRMAN WALLIS: Does it have water? 5 MS. UHLE: Yeah, yeah. Air, water. So it is no 6 face change. 7 CHAIRMAN WALLIS: So why does it increase 8 interfacial area? The bubbles are growing? 9 MS, UHLE: Well, no, the data decreases. 10 CHAIRMAN WALLIS: Well, why does the flow regime 11 base predict the increase? 12 MS. UHLE: No, it is decreasing? 13 CHAIRMAN WALLIS: The top current. The flow 14 regime.
) 15 MS. UHLE: Oh. Oh, sorry, yeah. Okay, I can get 16 into that, but hold on. Can I --
17 CHAIRMAN WALLIS: It is sort of like bubbly flow 18 regime, so there is not a regime change. 19 MS. UHLE: This is the data, essentially the data 20 is, you know, you put in some bubbles of air in the bottom 21 and you are going up this -- how many -- it was like 10 foot 22 long pipe. And at this particular conditions of flow, the 23 bubbles were hitting each other, it was called random 24 collisions, and they were agglomerating. And when you take 25 two bubbles and you moosh them together, you are getting a
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I 285 1 reduction in interfacial area. 2 CHAIRMAN WALLIS: That's right. 3 MS, UHLE: And this particular process was 4 dominating rather'than, you know, the process which can 5 actually break up bubbles and create interfacial area, even 6 though you are keeping void fraction the same. So you are 7 seeing this reduction in interfacial area. 8 DR. KRESS: Is this turbulent flow? 9 MS. UHLE: It was -- I mean the diameter is small 10 and the void fraction is real low, so it was -- well, we 11 didn't have any turbulent-induced breakup at this. So, no, 12 I don't know what the exact Ringhals number was, but it was 13 on the low side and there was no actual -- based on the 14 model that I put in the code, there was no interfacial area 15 increase due to this. 16 CHAIRMAN WALLIS: The flow regime base looks like 17 just a pressure drop expanding the bubbles. 18 MS. UHLE: But you still need an area. Okay. So, 19 anyway, when I put in the interfacial area model, I just put
-20 it in for a pipe, because that is all the data we have right 21 now. And so I essentially put in the inlet condition for 22 the interfacial area, and I let it propagate through the 23 pipe, with the one group interfacial area model that has 24 been developed at Purdue. And so you see it is working with 25 the code, it is calculating the area.
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I i l 286 1 The interfacial area then goes into the sub-() 2 3 routine. It evaluates the interfacial drag, and it takes this interfacial area I calculated and multiplies it by, you l 4 know, the bubbly flow drag coefficient, you know, times rho 5 V squared, divided by two. And this is the result. This is 6 the interfacial area propagation. 7 In TRAC what is currently done is that it says, in 8 the crses of bubbly flow, it says the interfacial area is j 9 six times the void fraction divided by the Sauter mean 10 diameter, or DB. And then it says, okay, what is the Sauter 11 mean diameter? And what that really is supposed to mean is 12 if you took all the ranges of bubble diameters, what would 13 be the bubble diameter that would give you the same volume' l 14 to surface area? ; O) ( 15 DR. KRESS: If you had the same number of bubbles. 16 MS. UHLE: Right, if it was just one bubble. 17 Right, if it was just one bubble. 18 CHAIRMAN WALLIS: If it was growing. 19 MS. UHLE: Right. And in the TRAC code, they 20 needed to have this value, but there was really not a whole 21 lot of physical models dealing with this phenomena, so Ishii 22 at the time when the TRAC developers I guess callec Ishii 23 and asked him about this, and he said, well, the best 24 estimate I can give you would-just be to assume that the 25 Sauter mean diameter is equal to twice the Laplace number. ANN RILEY & ASSOCIATES, LTD. ON Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 m
i 287 l 1 Okay. So this is the Laplace number right here. l () 2 CHAIRMAN WALLIS: So the reason TRAC does so badly 3 is it has lousy physics, not because it doesn't track 4 interfacial area? l 5 MS. UHLE: Well, it doesn't track interfacial ) 6 area. l l 7 CHAIRMAN WALLIS: Interfacial area puts in some j 1 8 physics which was not in TRAC. I 9 MS. UHLE: Well, it needs an interfacial area and 10 it gets it in a way that is not physically -- 11 CHAIRMAN WALLIS: But if TRAC had put in the 12 agglomeration model, -- 13 MS. UHLE: Right, it would be better. 14 CHAIRMAN WALLIS: -- it could probably, it might () 15 well have done as well as interfacial area. So it is not 16 the interfacial area model which is the key, it is actually 17 modeling the physics. 18 MS. UHLE: Well, but that is what the interfacial 19 area model is. I 20 CHAIRMAN WALLIS: It forces you to model 21 agglomeration. 22 MS, UHLE: It forces you to model a little bit the 23 coalescence and breakup terms that are actually the 24 dominating phenomena that is causing the propagation or the 25 evolution of the interfacial area. And, see, what is jO* ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
4 1 288 1 happening here is that we are reducing pressure in the -( ) 2 bundle -- or, no, in the pipe, and the void fraction is 3 increasing just because of the pressure. 4 CHAIRMAN WALLIS: Right. l 5 MS. UHLE: Okay. And at the same time, the 6 Laplace number gives you a small diameter as you increase -- 7 as you decrease pressure. So these two combine to increase j 8 interfacial area. 9 CHAIRMAN WALLIS: It is very unrealistic. The 10 bubbles are growing because the pressure is dropping. 11 MS. UHLE: Right. 12 CHAIRMAN WALLIS: But TRAC predicts they get 13 smaller. 14 MS. UHLE: Right, right. And so, you know, that n (,,) 15 is why you are getting a different trend. But RELAP was far 16 worse. Is that RELAP? Okay, this is RELAP. We are off the 17 scale on this one. This is the data, this is the 18 interfacial area model in TRAC, this is RELAP. And RELAP 19 does wacky things because it uses the Weber number criteria. 20 And essentially what this does is, as you -- well, I should 21 say in upflow in the bubbly -- I'm sorry, in bubbly flow in 22 vertical pipes, it uses an interfacial -- sorry, uses a 23 drift flux model to backout the interfacial drag force. 24 Okay. 25 And I can go through some of the equations right O' ANN RILEY & ASSOCIATES, LTD.
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3 289 1 here. () 2 3 CHAIRMAN WALLIS: What are you are telling us is that, in fact, the physical models in these old codes, for 4 some purposes, are pretty lousy. 5 MS. UHLE: Well, they are not modeling the 6 physics, and, in fact, they give the opposite trends, which 7 is what happens. Okay. Like in RELAP, this is what it 8 says, it says in bubbly flow, my interfacial area is alpha 9 over D-zero and D-zero is one-half D-max. And D-max is set 10 by the Weber number, and they chose a Weber number of 10. 11 In other words, the bubbles, you know, when you get a _ , 12 breakup of a bubble, is it a Weber number of 10? 13 Okay. So this relies on what the Vg minus Vf term 14 is, but it was getting Vg and Vf based on the drift flux 15 result, because, you know, the drag term was dominating what 16 the relative velocity was going to be, 17 So as it all turns out, what happens in RELAP is 18 if you increase -- as you are reducing pressure in the pipe, 19 you are increasing alpha. And what that does is that it 20 causes drag to -- I am going to go in the wrong direction. 21 What does it do? It causes drag to -- 22 DR. KRESS: Decrease. 23 MS. UHLE: Decrease. You are right. It causes 24 drag to decrease. What that does is that increases Vg minus 25 Vf. This, therefore, causes smaller diameter bubbles, and O ANN RILEY & ASSOCIATES, LTD. \- I Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 m I
1 l l 290 . I 1 you increase interfacial area, much more so than if you had 2 used the' Laplace number. ())' w But still in the complete wrong 3 direction '.an if you used just a one-dimensional 4 interfacial area transport model. 5 CHAIRMAN WALLIS: There may be situations where 6 this breakup -- every number is modeling breakup here. 7 Vapor number is modeling breakup. And what is happening in 8 this experiment is actually agglomeration. So it is 9 modeling the wrong thing. But there are situations where 10 the breakup is important. 11 MS. UHLE: Right. 22 CHAIRMAN WALLIS: Or you can probably -- you can 13 probably find some data where RELAP does pretty well. 14 MS. UHLE: Yeah. C\ ( ,/ 15 DR. KRESS: And then your model wouldn't 16 accommodate that. 17 MS. UHLE: No, that is not my model. That is the 18 old formulation. 19 DR. KRESS: Oh, that is the old TRAC code 20 MS. UHLE: Yeah, this is the interfacial area 21 model that we put in the code. 22 DR. KRESS: I see. 23 MS. UHLE: This is the interfacial transport , 24 equation. Essentially it is just a time change in 25 interfacial area. ANN RILEY & ASSOCIATES, LTD. s_/' Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
i 291 1 CRAIRMAN WALLIS: Those Vs need some constitutive 2 models. 3 MS. UHLE: Right. And this is what Purdue is 4 doing. They are developing these constitutive models. And 5 I put the constitutive models into the code. I put this 6 equation into the code. I did it explicitly, in other 7 words, used old time values so it was very simple. It took 8 me three days. And it is just that in this particular flow 9 condition, what was dominating was the random collision. 10 CRAIRMAN WALLIS: Did they tell you how clean the 11 water was? 12 MS, UHLE: No. 13 CHAIRMAN WALLIS: Because I can show you 14 experiments which are oddly different depending on how clean (O,/ 15 the water is, for the same. 16 MS. UHLE: Yeah, for the random collision because 17 of surface tension and stuff. 18 CHAIRMAN WALLIS: Well, what you are pointing out I 19 is what va have known for years, that these codes - .that 20 someone has grabbed something out of the air and said we 21 will put this in here to model something. 22 MS. UHLE: Because we don't have -- 23 CHAIRMAN WALLIS: They didn't know what else to 24 do, and then they used it. And they didn't have the sort of 25 systematic comparison of have you really put in enough [) \_/ ANN RILEY & ASSOCIATES, LTD. Court Reporters l 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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292 1 physics to represent various things, because there was an fT 2 emphasis on getting on with it and running the code. ~V 3 DR. KRESS: So these four Vs you have, one of them 4 is the Weber number breakup? 5 MS. UHLE: Okay. This is turbulent impact. This 6 is the increase in interfacial area per unit volume due to 7 turbulent impact, and that is the Weber number kind of 8 thing. 9 CHAIRMAN WALLIS: It is an agglomeration. 10 Agglomeration, going together of bubbles. 11 MS. UHLE: No, no, no. That is -- hold on. This 12 is turbulent impact. 13 CHAIRMAN WALLIS: What does that mean? I don't 14 understand how that affects area. (9 j 15 MS. UHLE: Because if you have a bubble, right, 16 and you are at a high turbulent intensity of the -- 17 CHAIRMAN WALLIS: This is breaking it up. 18 DR. KRESS: It is like Browning motion causes more 19 agglomeration? 20 MS. UHLE: No, no, no, that is random collision. 21 DR. KRESS: Okay. Okay. Go ahead. 22 [ Laughter.] 23 MS. UHLE: All right. So this is turbulent 24 impact, is you have a bubble and you have a turbulent 25 ' intensity of the fluid, and it is the Weber number -- I want ANN RILEY & ASSOCIATES, LTD. ()N \s_ Court Reporters 102i Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 )
i 293 1 to say phenomena. [w ' 2 DR. KRESS: A turbulent Weber number. 3 MS. UHLE: And it breaks up, it breaks up the 4 bubble into two smaller bubbles. 5 CHAIRMAN WALLIS: It is based on turbulence rather 6 than relative motion 7 DR. KRESS: Well, I would like to see that model. 8 MS. UHLE: Okay. Well, I have the whole -- I mean 9 I certainly have the papers to show the whole derivation of 10 these equations. But that is generally what turbulent 11 impact is doing. 12 Wake entrainment is, you know, here is your bubble 13 and it is rising in the fluid and you have a wake behind it, 14 and bubbles are going to get caught in the wake and they are [ 15 going to rise faster than this bubble, and they hit and they 16 coalesce, so that reduces ir. arfacial area. 17 Random collision is Browning motion kind of thing. 18 You know, you are moving around and you hit each other and 19 you coalesce. That is going to reduce interfacial area. 20 And then this is a phase change term, and I was doing 21 air / water, so I didn't have a phase change term. 22 DR. KRESS: Now, are these things going to be the 23 same model for horizontal flow as they will be vertical, or 24 they will be different? 25 MS. UHLE: Well, that is what they are working on
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294 1 now is getting these equations, you know, the formulation / 2 or these source and sink terms for the specific flow 3 conditions and geometry. 4 CRAIRMAN WALLIS: There is no breakup here due to 5 relative motice ? 6 MS. UHLE: What? 7 CHAIRMAN WALLIS: If you accelerate a flow, and 8 you accelerate -- you are going to increase the ,: elative 9 velocity, you tend to breakup the bubbles. It doesn't seem 10 to be in there. 11 MS. UHLE: That is the turbulent impact. . 12 CHAIRMAN WALLIS: No, no, no , no. This is just 13 because -- the bubbles move faster than the liquid. ! l 14 MS. UHLE: Yeah. l l (j 15 CHAIRMAN WALLIS: If there is no turbulence at l 16 all, they still will break up because they are moving too 17 fast. If you accelerate a flow, the bubbles accelerate 18 faster than the liquid. 19 MS. UHLE: Yeah, but that is the Vg minus Vf t 20 term -- l 21 CHAIRMAN WALLIS: That's right. 22 MS. UHLE: -- of turbulent impact. 23 CHAIRMAN WALLIS: No , it's turbulence, it is just 24 relative motion. 25 MS. UHLE: Well, okay, but that is the term. That l i
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l 295
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1 is what they called it. () 2 CHAIRMAN WALLIS: So what you are essentially 3 saying, if you put in more physics, you can fit more data? 4 MS. UHLE: Well, yeah, you can fit more data, you 5 are getting the right trends. In fact, what that process -- 6 Farouk had showed you the subcooled boiling. That was a l 7 result because the interfacial area prediction in RELAP was 8 off scale.
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9 CHAIRMAN WALLIS: Yes. 10 MS. UHLE: I mean it turned out that their 1 11 interfacial heat transfer coefficient was way too low, so it 12 shouldn't have been condensing all the vapor that it was, ; l 13 but the interfacial area was too high. So they multiplied 14 those together and they got something reasonable for the i
<- I k)g 15 condensation. The drag term was way too low, so that caused 16 the void fraction to stay higher. And then you had the 17 subcooled boiling which was too low, so you moosh all those !
18 together and you get some prediction of void fraction, but 19 you are -- you know, if you look at each of the individual 20 pieces, they are all sort of wrong. It is just when you 21 push them together, you know, you get a prediction. 22 CHAIRMAN WALLIS: There is probably some history 23 in the past of ACRS approving RELAPS without knowing this. 24 MS. UHLE: So, at this point in time -- 25 DR. SCHROCK: Not willingly. / ANN RILEY & ASSOCIATES, LTD. \- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
a 296 1 [ Laughter.)
.2 MS UHLE: So at this point in time we are still 3 taking, you know, data. There is really no database for 4 interfacial area work. The instrumentation-has mostly been 5 developed at Purdue,.some at CEA in France. There is work 6 in Japan, you know, in France at CEA, as well as at Purdue, 7 and the University of Wisconsin, Madison, which is Professor 8 Kojasoy. And they are all working to get these source and 9 sink terms for various conditions.
10 MS. KRESS: Do they take pictures? 11 MS UHLE: Oh, yeah, they take pictures. Yeah. 12 DR. KRESS: And count the area? 13 MS. UHLE: They actually do some -- they have the
- 1. conductivity probes and they -- what is the word -- verify 15 the results against pictures. But then they mostly use the 16 interfacial -- or the conductivity probes because it is 17 fast, and they don't have to --
18 DR. KRESS: That takes forever on pictures, I have 19 done that before. 20 MS. UHLE: But their facility is very interesting. 21 CHAIRMAN WALLIS: It depends a lot on your 22 measures of success, and some folks would simply say that it 23 doesn't matter what you do here, the peak clad temperature 24 in LOCA is insensitive, so it doesn't matter. 25 MS. UHLE: I knew you were going to say that. O k> ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 n i
297 1 [ Laughter.] (A
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) 2 CHAIRMAN WALLIS: Others have said before the 3 committee. I am just repeating it. !
4 MS. UHLE: Okay, so why do we need this and who l 5 really cares? 6 CHAIRMAN WALLIS: Good. 7 MS. UHLE: Okay. So why do we need this and who j 8 really cares? This is an example of how a static flow l 9 regime map may not generate conservative results and this 10 was seen for the AP600 work in the NRC 25 tests when Farouk 11 had mentioned that they saw a dry-out at the facility but 12 the mode didn't show a dry-out. l 13 This is the cype of thing that can happen. The l 14 two phase mixture is going into a core here, and it is O (j 15 producing slug flow. It is then going into this hot leg. 16 CHAIRMAN WALLIS: I wonder what slug flow looks i 17 like in a core, frankly. 18 MS. UHLE: Well, I know but anyway based on the 19 hydraulic diameter it says it is slug. 20 So then it is entering into the hot leg. Now I am 21 just postulating that there is an ADS valve of some sort 22 located in this particular position. I ran RELAP in this 23 case -- at the time it was easier for me to run RELAP than 24 it was TRAC so it was about a year ago that I was doing 25 this. Anyways, you put in a two phase mixture. The code
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298 1 says it is immediately stratified when it enters the hot m s _j
) 2 leg, and in this particular case then you are venting vapor 3 and you are depressurizing while maximizing the liquid in 4 your core.
5 If you actually do a back of the envelope 6 calculation, you say, okay, well here is my bubbly flow. In 7 order to formulate horizontal stratified conditions I know 8 that the bubble rise velocity of .2 meters per second has to 9 rise up to the diameter of the pipe and that is on the time 10 scale for development of stratified flow. 11 If you do that based on the conditions of the raw 12 liquid velocity being this, the time to develop is 4.5 13 seconds, which puts you out at a 6 or 7 L over Ds, so here 14 the code is producing a nonconservative result, whereas if ( ) 15 you had actually a timescale of development you would 16 hopefully be farther out here, so here is an example of when 17 you would care. 18 CHAIRMAN WALLIS: I suspect there are many 19 examples where you care and no one has -- there has been a 20 force of work to not care and there's been pressures to not 21 ask these questions. 22 I can summarize here or I could just simply say 23 whatelsewearedoingapthedifferenttestfacilities-- 24 the phase separation at tees and the subcooled boiling at 25 low pressure. I think you are all aware of that. At one ANN RILEY & ASSOCIATES, LTD. _ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
299 1 point we had mentioned it. Is it okay to summarize? () 2 In summary, the current code capabilities will be 3 incorporated into the consolidated code and mostly to 4 minimize the dilution of resources and help us develop in-5 house expertise because we are heading in a direction where 6 we are relying less and less on contractors. 7 The consolidation will follow consistent SQA
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8 procedures to make sure that the documentation is around so 9 that future code developers can actually learn to work with 10 the code and use the code. 11 The NRC is currently maintaining configuration 12 control and will continue to do so. 13 Concurrently improvements will be developed and 14 merged with the consolidated code as they are developed. () 15 We are saying that user needs will be accommodated 16 by making sure that we cover all of the capatttities and 17 also making sure that people are prepared to move over to 18 the consolidated code. This will be facilitated by the GUI 19 work. The GUI work will -- in the spring we should have the 20 capability to do have the GUI developed for TRAC so that we 21 can actually start to use the GUI for TRAC to produce input 22 decks and then shortly thereafter have the ability to run 23 RELAP5 decks with the consolidated code through the GUI. 24 Again the consolidation will help develop NRC 25 Staff expertise. We are. currently taking data so that model ANN RILEY & ASSOCIATES, LTD. n\/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
If T 300 1 improvements can be completed in a timely fashion and we are
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(x ) 2 taking data and doing model development work in the area 3 that deficiencies have been identified. And that's it. 4 CHAIRMAN WALLIS: I hope some of this improvement 5 keeps going. I mean you and Joe Kelly have both discovered 6 things which the old codes didn't do well and stated 7 improvement and it would seem naive to assume that you have l 8 found them all. 9 MS. UHLE: I don't think we have found them all, 10 but one thing -- having one code anyway, if you take all the 11 users that there are just on one code, I think some of these 12 issues will arise much quicker than if you had two codes, j 13 and the fact that it is easier to develop, and I think these 14 things can be improved quickly. Again, it didn't take too
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(,,) 15 long to become familiar with the code to start to do some 16 bug fixes and some simple model work -- incorporating models l 17 into the code. That's it. 18 MR. ELTAWILA: Somehow -- do you want to take a 19 break or do you want to continue? 20 CHAIRMAN WALLIS: I was going to tell everybody 21 here that there is a sort of suspicion that the Government 22 may close tomorrow because of this hurricane and we are 23 asked to check the radio to see if we should come to work. 24 MR. BOEENERT: Yes. 25 CHAIRMAN WALLIS: That indicates to me that we [\~/} ANN RILEY & ASSOCIATES, I .TD . Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 i
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4 301 1 should not put off until tomorrow John Mahaffy's. We should ( 2 just go ahead with it. ( 3 I do want to take a break for, say, five minutes. 4 DR. KRESS: Does it matter what radio station you 5 listen to? 6 MR. BOEHNERT: I would say TOP is the best one, 7 1500 AM. That's the best. ) 8 (Recess.) . 1 9 CHAIRMAN WALLIS: We will come back in session. 10 MR. MAHAFFY: I am John Mahaffy from Penn State 11 University. 12 I have been working on something.that falls in the 13 category of new feature in the code. Most of what is going 14 on has to do with consolidation, making sure that we.have f-~s I ( ,) 15 the existing capabilities from a group of four codes. This 16 is something a little bit different and I am titling it 17 "Multitask and Parallel Computing with the Consolidated I 18 Code." 19 Let me just define some things for you, so I am 20 precise in what I am saying. 21 If you talk about multitask computing, I am 22 talking about the consolidated code working in conjunction : 1 23 with other programs to produce a full system simulation. 1 24 In general, these programs are going to be each 25 operating on a separate processor, on some sort of a I [)
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y 302 1 multiprocessor computer. When I talk about parallel l 2 computing, I am talking about a single run of the k.)) 3 consolidated code that is using parallel directives, such as 4 there is a standard now called Open MP, to allow you to work 5 very effectively with multiprocessors and particular where 6 you are targeting a shared memory environment there. 7 My primary focus is on multitasking. What I am 8 trying to do with this particular piece of work is to expand 9 the range of capabilities of your system analysis tool to 10 allow you to plug in very easily specialized analyses. 11 However, one of the nice benefits of it is that you get a 12 code that is structured to do parallel cotaputing very well 13 also. l 14 Quick definition: Parallel architectures, when I (G) 15 talk about distributed processing, which works well with the 16 multitasking, you have got a bunch of CPUs with memories 17 linked together by a backplane or a fast Ethernet or i 18 whatever -- 19 DR. POWERS: When you say a bunch, are you talking 20 four, as illustrated? 21 MR. MAHAFFY: It may be four, it may be 20. 22 DR. POWERS: That's not like thousands? 23 MR. MAHAFFY: This type of calculation does not 24 tend to work well in thousands and for the type of thing I 25 am about to show you, we are talking about small numbers for [~) ANN RILEY & ASSOCIATES, LTD. Court Reporters 's / 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 a A
303 1 the multitasking simulation. You get some more pictures
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2 there. f) 3 We did work at Los Alamos in the early '80s doing 4 efficiency studies, parallel efficiency, and we found for 5 these class of problems you get very high parallel 6 efficiencies if you are running in a few los of processors. 7 When you get into thousands of processors your parallel 8 efficiency drops. 9 DR. POWERS: I guess the only thing that disturbs 10 me about that is you say you did work at Los alamos in the 11 early '80s or '90s -- 12 MR. MAHAFFY: Early '80s. 13 DR. POWERS: That is several generations of the 14 massively parallel machines now and people do run -- () 15 MR. MAHAFFY: I understand. 16 DR. POWERS: -- thermal-hydraulics and mechanics 17 codes now in massively parallel systems. 18 MR. MAHAFFY: What you will see as I get further 19 is that I am not forbidding you from running massively 20 parallel. You can do it. I am telling you that I believe 21 if you look at the code architecture your parallel 22 efficiency will take noticeable hit as you get above a few 23 10s of processors. 24 DR. POWERS: I guess I have heard you say that. I
.25 mean it just runs counter to the trends in these codes.
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1 l 304 1 MR. MAHAFFY: I understand, but again we will look () 2 3 at the goals I am trying to do. Okay. Here's my goals in multitasking. Basically l 4 I want to increase the capabilities of the code and I want 5 to be able to introduce special. component models, special l 6 process models without somebody having to have a detailed 7 knowledge of this consolidated code. We want to be able to 8 plug in extra modeling capabilities and here's some things I 9 that you might be able to do. 10 We are going to do a demonstration on an 11 accumulator model. You might want some special -- the 12 Grangian type model for a core makeup tank in an AP600. You 13 want to be able to easily plug that in. You might want to 14 plug in a CFD code. The consolidated code is providing in I Q i s f 15 effect full system feedback boundary conditions to a 16 detailed CFD analysis of a limited area, the plenum and the 17 steam generator, the lower plenum in a vessel, that sort of 18 thing. 19 CHAIRMAN WALLIS: These are the sort of things 20 that we had in our wish lists at previous times we met with J 21 you guys and I thought you weren't going to do it. You are 22 actually going to do these things? 23 MR. MAHAFFY: We are introducing the capability. 24 CHAIRMAN WALLIS: As part of code consolidation? : 1 25 MR. MAHAFFY: Right now, as of two versions down l l
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e , 305 1 the line, this exterior interface will be in place -- I am 2 not telling you this is trivial, but I am going to have -- 3 CHAIRMAN WALLIS: It is happening though, you are 4 telling us. 5 MR. MAHAFFY: The plug will be on the outside of 6 the code and the capabilities to talk in a more implicit 7 fashion to other fluid calculations such as CFD will be 8 there. Somebody will have to invest time to adapt the 9 interface to the CFD side so it could talk to this, and that 10 is money, and somebody has to make a decision at some point 11 to invest that but it is doable. 12 You might want to be able to improve your physical 13 processes, neutron and radiation transport. We are looking 14 at, for instance, you heard about PARCS. Right now it has 0 d 15 its own special parallel interface into the code. It can 16 adapt to the interface that we have developed here so it is 17 just part of a family of codes that connect via this plug- l l 18 in. 19 All right. You could do special control system. 20 part of my distribution has an example problem where I have r 21 a parallel process that is doing a special control system 22 that controls the operation inside the code. One type of 23 special control system is something we used to call the 24 Nuclear Plant Analyzer. I can have a second process plugged 25 into the consolidated code that is extracting variables for ANN RILEY & ASSOCIATES, LTD. [] V Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 W - 1
306 1 real-time graphics that are displaying the graphics as the () 2 calculation proceeds, and it can have feedback. You can 3 work in true analyzer mode where your engineer is sitting 4 there and saying, okay, well what would happen if I opened 5 this valve and I hit some key in my other program that 6 represents a valve opening and it feeds that back real-time 7 to the ongoing calculation. A valve opens and you look at 8 how your calculation evolves. 9 CHAIRMAN WALLIS: I will ask you about this second 10 bullet again here, when I am dealing with something 1114 11 pressurized thermal shock. 12 I may be interested in using the usual kind of 13 system code to figure out what is happening in the whole 14 circuit but when I look at the plume and the downcomer I may (~% (,) 15 want to use FLUENT or something. 1 16 MR. MAHAFFY: Yes. l 17 CHAIRMAN WALLIS: This is going to let me do_that? 18 MR. MAHAFFY: It will make it a lot easier. You 19 are going to have to invest the time to put our interface 20 onto FLUENT. We have something called the -- l 21 CHAIRMAN WALLIS: Maybe if they see a market for 22 FLUENT -- 23 MR. MAHAFFY: If they saw -- yes. It is not 24- difficult to do. It is a fairly compact interface. The 25 actual amount of things you have to do to plug in it is /^l \~-
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r 307 1 fairly limited. I will get to that in a later viewgraph, () 2. 3 okay? CHAIRMAN WALLIS: And it is compatible? I mean 4 you can actually -- ; I 5 MR. MAHAFFY: If FLUENT can talk to FORTRAN 90 6 subroutines, they can pick up most of the work. It's' 7 already been generated. I have some very isolated modules 3 that constitute the bulk of this communications interface. 9 I have some rules about how you talk in an implicit fashion 10 with fluid connections, if that is what you want to do. 11 CHAIRMAN WALLIS: That seems to be important too, 12 yes. 13 MR. MAHAFFY: An explicit fluid connection is 14 trivial, but as you know you pay a heavy time-step price. px ( ) 15 You can crank up, for instance, to a semi-implicit 16 level that will get your time-step a lot higher and. feel a 17 lot better about your results. 18 CHAIRMAN WALLIS: Why did you do.this? 19 MR. MAHAFFY: Why did I do this? Because of all - 20 - the goal basically is flexibility. 21 CHAIRMAN WALLIS: Didn't you do it because some 22 users said they'd like to have this facility? 23 MR. MAHAFFY: Well, yeah, I heard the ACRS, but 24 this was in my plans before I heard ACRS saying it. 25 CRAIRMAN WALLIS: So, you dreamed before we did? [} s-- ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l- i
1 308 1 MR. MAHAFFY: I dreamed this a long -- I do
; 2 dreaming. It's just one of the things I do, People have wJ 3 been looking for increased flexibility. People have been 4 looking for one-time improvements. As we will see, this is 5 -- this, also, enables parallel. I can -- well, let me get 6 you some pictures here. We'll talk about it here. We're 7 going to decrease run times here by combining parallel 8 execution; but, also, you may be able to take advantage of 9 some simplified models in parts of your system simulation 10 through plug-ins.
11 Here's a picture of some sort of a calculation 12 using this type of an interface. I work with a central 13 process, special process sort of model. If you're going to 14 work in a standard sort of mode with TRAC-M, you can get
) 15 around this, if you understand the interface well enough; 16 but, you normally use TRAC-M consolidated code as your 17 central process. l It would be modeling part of you reactor j 18 system. You could have other TRAC-M processes running, 19 talking through this interface. It does it right now.
20 That's part of the default mode. 21 I might have another input deck that modeled the 22 secondary side of one steam generator. I'm doing another 23 secondary somewhere else on another input deck. I've got a 24 reactor containment plugged in here. I can use this t 25 interface and adapt the real CONTAIN to this interface, if / ANN RILEY & ASSOCIATES, LTD.
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309 1 that was important to somebody. I could have another (.n) \d 2 special process taking care of my reactor kinetics. Here's 3 what I'm talking about, small numbers of processors for a 4 typical application for this kind of a way of looking at 5 things. 6 Now, hidden in this, we can work in dual mode. If 1 7 you're really gong ho to run parallel, because to implement 8 this, I had to stuff to try to make it highly l l 9 parallelizable, this thing may, in reality, be running on a 10 shared memory processor and it may be grinding with some 11 large number of processors and talking out through whatever , 1 12 your communications channel is, Ethernet, to some other I 13 processes thac are doing special things. So, there are two 14 levels of parallelism here. C\ (_j 15 CHAIRMAN WALLIS: They will have to be in the same 16 place. I mean, some contractor can plug in from France or 17 something with some piece of this thing. 18 MR. MAHAFFY: Well, you just assume not be -- 19 you've got to understand, there's a lot of overhead time 20 associated with communications and you just assume they were 21 located close together and running over at least a high 22 speed Ethernet to get decent performance out of this or you 23 could take a big hit. Eut, yes, in theory, I could be 24 running one in France, one in the U.S.A., one in Russia, one 25 in Japan, and they can all be talking together. /^\ ANN RILEY & ASSOCIATES, LTD. (-) Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 a
k I 310 1 Okay. A couple of benefits to this multitasking 2 approach. I'm delivering a far more adaptable code. And 3 one reason that it's far more adaptable is you need far less 4 knowledge of the interiors of the consolidated code, okay. 5 CHAIRMAN WALLIS: Now, if fluid is actually being 6 involved and mistaken developed -- do they need -- they 7 don't need to know anything about what you're doing with 8 TRAC, right?- 9 MR. MAHAFFY: What they need to know -- I'm going' 10 to give them a dictionary of the meaning of certain 11 variables, okay, and I'm going to give them the definitions 12 of some argument lists in T-sub routines in my interface and 13 they're going to -- this whole thing is request driven. 14 I'll go ahead and drift into some of that for you in a 15 minute. You will see it's a very easy interface to use. If 16 you understand the meaning of certain key words and-the 17 meaning of certain location -- okay, if you know that you've 18 got to get information -- you need void fraction, which is 19 ALP for alpha, out of component three and cell four, you 20 just issue a very simple request and you've got it. ., 21 And there are certain negotiations that go on. If 22 you're going to do a fluid connection, you have to be able 23 to respond to a request from the main TRAC process for 24 certain -- again, ASCII strings. This is a very simple 25 level. The TRAC says -- it sends a little string out ALP, I l O ANN RILEY & ASSOCIATES, LTD. O CourtAvenue, Reporters
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311 1 want void fraction on number four -- component four and r ( 2 number three -- cell three, very readable, very easy to use. 3 Okay. And, again, the other benefit is increased 4 efficiency. We're going to be looking at more rapid 5 turnaround of analysis and, again, from parallel and 6 multitasking. 7 All right. I'll go this far and, unless you've 8 got special questions, I'm not going to go any further into 9 the details of this interface, except for one little view 10 graph. The enabling technology is something I call the 11 exterior communications interface. There's a' package of 12 subroutines. They're organized in Fortran 90 modules, very 13 complete. If you have a new application, for instance 14 FLUENT, and you want to use this interface to talk to TRAC, Q 15 there are four subroutines you must go in and change. Those 16 four subroutines give the interface access to your internal 17 data structure and they provide knowledge of the data 18 dictionary, so you can respond'to request for void 1 19 fractions, velocities, densities, etc. 20 The communications are requests driven. At the 21 beginning of the calculation, all of the codes that are 22 participating negotiate. I need void fraction from you. j 23 Oh, okay, well, I need void fraction from you, too, and 24 probably need the velocity, whatever. 25 CHAIRMAN WALLIS: We have to work together to
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T 312 1 calculate what the void fraction is going to be in the next tv ) 2 period of time. It's not just I need something. It's more 3 than'that to work together to solve something 4 simultaneously.
-5 MR. MAHAFFY: That's -- yeah, So, now, there are 6 a set of rules. I have a set of rules and I was going to 7 skip that, but if you want me to go into it --
8 CHAIRMAN WALLIS: Just to help us -- 9 MR. MAHAFFY: Yeah, there are certain rules on how 10 you solve the equations. 11 CHAIRMAN WALLIS: Right, right. 12 MR. MAHAFFY: Basically, you decide -- what 13 happens is a given process says, I'm going to solve --'in a 14 semi-implicit model, I'm going to solve all my variables, in (7) ., 15 terms of pressures in adjacent processes that I don't know I 16 yet. Everybody does the same thing and then you gather all l 17' those remaining pressure equations and you solve them in
'18 your solver. process. The solver process may be the central 19 process. In a CFD application, it's probably the CFD code
-20 that would be that final solution, because it's involved in 21 a much more exotic solution scheme. But, yeah, that's part 22 of what negotiation is, is how we're going to solve this.
23 Agein, requesting the data, if there's one 24 keystroke routine in all of this that I call is missing, you 25- . declare certain variables to be missing from your contacts
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313 l 1 and you just say, I need them. You don't even have to know ' 2 what process those variables are in. You just have a l 3 certain naming convention. People have to agree on the 4 concept of numbered components. I need this information i 5 from component four, cell three, and it goes out and finds 6 where that'is or it issues an error message if it can't find l 7 it. Part of the request is that you have to ask for these { 8 variables at certain points in the computational sequence, 9 also. And I provide a template to get the proper 10 synchronization points in the calculation for any other code I 11 that wants to match the key synchronization points in TRAC-12 M. 13 All right. A quick schematic from late in the 14 game, somewhere -- here we go. I'll show you what's going ( 15 on. There are two processes talking to each other. The 16 communications interface schedules up-front all the data 17 communications. It sets up what are called transfer tables, 18 so that at particular intervals of time, there's a pulse 19 that moves system data into the next forward transfer 20 buffer. It then copies that buffer to an in-board buffer 21 via-standard process to process communications protocols. 22 And then it -- on this side, it drives a transfer into the 23 local data structure. These transfers are very fast once 24 they get going. And, again,.all the expense is up-front in 25 negotiations and the knowledge that people have to have, in ANN RILEY & ASSOCIATES, LTD. L. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202)' 842-0034 A
314 1 terms of users, is fairly lov. ( ; 2 CHAIRMAN WALLIS: I guess the thing that I am most
'R J 3 interested in is what it will do and that the reason we 4 might want to know some of these, as to how it does it, is 5 just simply to satisfy ourselves that you know what you're 6 doing.
7 MR. MAHAFFY: Okay. 8 CHAIRMAN WALLIS: But, if it will do the things 9 that you claim it will do, that would -- that's the thing 10 I'd be the most interested in. 11 MR. MAHAFFY: Well, I sort of -- I've made my 12 claims about what it would do. What kind of clarifications 13 would you like on that? 14 CHAIRMAN WALLIS: Well, will it do it? ,, -~
) 15 MR. MAHAFFY: It's doing it right now. I don't 16 have a CFD code plugged in, but I've got various examples.
17 In effect, my examples on flow right now are limited to TRAC ) l 18 talking to itself. But, those are examples -- 19 CHAIRMAN WALLIS: What's this thing with what Dr. 20 Uhle told us about? I mean, is this -- is this part of your 21 code development or is this a new thing? Is this the -- 22 MR. MAHAFFY: No. 23 MR. ELTAWILA: It's part of the plan that we put 24 alcng. Because, eventually, if you think about NRC code, we 25 have a code called the Lab 5 SCADAP code, which should link
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315 1 the CV axial code to the thermo hydraulic code. So, in 2 eventuality, that we are going to rely on the TRAC code, we 3 won't couple the CV axial package into that code. And 4 that's what was planned from the beginning, conveyed it in 5 the plan, that that's what was our intention. 6_ CHAIRMAN WALLIS: I see this going much further 7 than that, though. Once you have all these capabilities, 8 people will think of ways to use them, if you have a 9 creative agency. 10 MR. ELTAWILA: Okay. 11 CHAIRMAN WALLIS: Well, that's the way with 12 computers. Unless you find out that you can do things, then 13 people will find some way to make some use of them. 14 MR. ELTAWILA: I understand. But, we have planned 1.5 to be able to consolidate all of our activities that 16 investigate accident in the CONTAIN, if we intend to contain 17 -- 18 MR. MAHAFFY: Let me give you a different 19 perspective on that, also. As a university professor, I 20 like to be able to create clean, isolated projects for 21 students and this does a nice job of that, because, now, I 22 can have a well-established accepted system simulation code 23 and it can be sitting there telling me aboat what's going on 24 in a full system. And then a student can focus on some kind 25 of e. model of some local region and learn more about that l ]/ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 j (202) 842-0034 j i i
l 316 1 with reasonable boundary conditions to that. 2 CHAIRMAN WALLIS: This is just for -- we've talked 3 .about before, it is a wish. Although, I don't think it's 4 coming from the agency, it's coming from people like 5 professors, these are great things to do. 6 .MR. MAHAFFY: The agency said, you know, there is 7 -- the agency has had its own needs that this fulfill and 8 this is probably the only way you can do it. It is -- it is
- 9. a more generalized version of some of the things the agency 10 has been trying to do for a number of things.
11 Okay, a predecessor of this is the linkage that 12 Jennifer talked about between PARCS and the consolidated 13 code, PARCS and RELAP5. That is a multitasking type of an 14 operation. It's a very.hard wired interface. You can't (O g ,) 15 reuse that for other codes. What's going on here is I've 16 created a more flexible reusable interface and part of the 17 interfacing is this ability to do more implicit solving of 18 flow equations. 19 CHAIRMAN WALLIS: I would think that there'd be 20 great tension between you and the regulators, because you're 21 actually providing other capabilities, which, in a sort of 22 common sense way, make a lot of sense. But, when someone 23- has to write regulations about what you're allowed to use 24 and how you are to use it, the last. thing they want is
- 25. tre nendous flexibility in all kinds of -- how you're going ANN RILEY & ASSOCIATES, LTD.
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317 ! 1 to make regulations, you know, that restrict and spell out () 2 what you can and cannot do, if you've got all these 3 different abilities coming out. 4 DR. KRESS: The difference is that it's NRC that's-l 5 going to use this code, not the licensee. ! 1
-6 DR. POWERS: It seems to me that this is something 7 that's very useful for the research organization. It's not 1
8 all --I can imagine, well, it could be some day a code that 9 Uses the structure booklet for the LAN organizations; but, 10 by and large, it's a research tool. I l 11 DR. KRESS: It's a research tool. But, you know, I I 12 what I -- 13 DR. POWERS: That's a non-negligible issue. 14 DR. KRESS: But, it gives you newer capability. () 15 Can I' answer a question, Dr. Stein did order two private -- 16 because, you can plug in -- 17 DR. POWERS: The opening speaker made a very-18 strong point, that the biggest user of these NRC code -- is, 19 in fact, research, because they have research questions.or 120 detailed type of-progressions. So, it's -- I mean, I'm not 21 blaming them for that, it just hasn't addressed the LAN 22 organization'need. , 1 23 CRAIRMAN WALLIS: Yeah, but then the agency as a 24 whole has-to appreciate-the need for those research type 25 questions to be asked. ANN RILEY & ASSOCIATES, LTD. i [~'} s- - s Court Reporters 1025 Connecticut Avenue, NW,' Suite 1014 Washington, D.C. 20036 (202) 842-0034
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i 318 1 DR. KRESS: I think the LAN organization will come I 2 up with some -- 3 CHAIRMAN WALLIS: Well, the LAN organization has 4 asked more adventurous questions when they know that 5 capability exist, because -- 6 DR. KRESS: Yes, that's what I would say. 7 CHAIRMAN WALLIS: I mean, they're not -- so, it's 8 evident that they're intimately involved in this. 9 MR. MAHAFFY: You've raised one inceresting point 10 that I want to address before we quit on this, and from a 11 regulatory standpoint, there is one thing that we have to 12 provide. It's not fully implemented in my first update to 13 the consolidated code, but when you run this in a 14 multitasking moua on all output, there has to be a clear ( ,/ 15 indication that there are other players, beside you, to 16 officially epp;.ove consolidated code, because you don't want 17 to be in a situatt.un where you think you're running the 18 consolidated code with officially sanctioned models on some 19 simulation, and somebody's got a side program over here 20 bottling some key component with unapproved models. 21 CHAIRMAN WALLIS: That's what I see as a problem. 22 You may build in so much flexibility that it's very 23 difficult for the regulator to decided what's allowable and 24 what's not. 25 MR. MAHAFFY: There's got to be a list of approved
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J 319 1 connections to this. () 2 DR. KRESS: Can Joe Paterno use this? 3 MR. HOCHREITER: Sure. 4 CHAIRMAN WALLIS: Do you want to try to get 5 through tomorrow's program, as well, today? 6 MR. ELTAWILA: Yeah, I want to try to.
- 7. CHAIRMAN WALLIS: How long are you going to take, 8 Larry?
9 MR. HOCHREITER: I can really -- I can go through 10 this pretty quick. I'm going to talk about the transfer 11 program. And this is our outline: the background;
'12 objectives of the program. The program is organized by 1 13 tasks. And we talk about the facility design and status 14 and, of course, the conclusions.
() 15 For background -- some of this has been covered , 16 'already in previous presentations. With the advent of best 17 -estimate methods being approved, plants can get to higher 18 kilowatts per foot for the same peak cladding temperature, 19 okay. And now,.many of the calculations are approaching . 20 2200 degrees and Farouk showed a slide of that. 21 As you'll approach 2200. degrees,.you have a 22 greater need for accuracy and making sure you understand the 23 code and the.models and so forth. And, of course, the NRC 24 needs an accurate audit. tool, to be able to verify the 25 vendor calculations. As -- ['\ ANN RILEY & ASSOCIATES, LTD. '\ l Court Reporters 1025 Connecticut Avenue, NW,. Suite 1014 Washington, D.C. 20036 (202)'842-0034
320 1 CHAIRMAN WALLIS: It's risk informed, not risk 2 informable. 3 MR. HOCHREITER: Oh, okay. The TRAC model, again 4 Farouk showed some slides, this has got to be improved, 5 before we can really do assessment. And the area that we're 6 looking- at primarily is in disperse, flow, foam boiling. heat 4 7 transfer. This is where the calculated PCT occurs. This is 8 where the largest uncertainty is. There's a very low heat-9 transfer value there. You have several phenomena, which 10 interact together, to give you the heat transfer. And if 11 you adjust one particular phenomena, you can be creating 12 compensating error. And it's in this range that spacer 13 grids make a major importance. 14 DR. KRESS: Do spacer grids break up the drops and (O,j 15 the -- 16 MR. HOCHREITER: The drops. They mix the vapor. 17 DR. KRESS: -- and mix the vapor. 18 MR. HOCHREITER: They quench. j 19 CHAIRMAN WALLIS: They're being trained? ; 20 MR. HOCHREITER: They're being trained. They're 21 retrained. So the regimes that we're looking it a flooding 22 regime, and that's the low point regime. Usually, this is 23 not a problem, either from a calculational point of view or 24 from each transfer point of view, because you're overwhelmed 25 in a situation with flow, okay. So, you have a crude model f~T; ANN RILEY & ASSOCIATES, LTD. N/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 % , Washington, D.C. 20036 (202) 842-0034 i
321 1 and you'll get about the right answer; maybe for the wrong / j 2 reasons, but you still -- 3 CHAIRMAN WALLIS: So, that always happens? 4 MR. HOCHREITER: Well, the problem is this may 5 happen only at the very beginning of the transient and then 6 it disappears, because it's not a forced flow situation. 7 It's a gravity flow situation. Generally, the regime you 8 get is this regime, where you're actually blowing below the 9 quench front and you break up all the liquid that was here 10 into drops and you're in the disburse flow foam boiling 11 regime, which is really a regime for heat transfer, because 12 you are exiting liquid out of the bundle, so you don't get a l 1 13 chance to evacuate at all, and the steam superheats to { l 14 almost the rod temperature.
~'x
)
l () 15 This is just a better artist conception. For ' 16 those rates, it's this regime that dominates, okay, and it 17 can be eight feet high in the rod bundle. I 18 CHAIRMAN WALLIS: But, it's not as -- it's not 19 constant? I mean, it's -- 20 MR. HOCHREITER: No. 21 CHAIRMAN WALLIS: -- transient. The stuff 22 splashes up -- 23 MR. HOCHREITER: It's a transient, because you 24 have a quench front that's moving up slowly. 25 CHAIRMAN WALLIS: It, also, is not just a linear j ANN RILEY & ASSOCIATES, LTD. s- Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 h A
322 1 transient. Stuff splashes up and -- [') s/ 2 MR. HOCHREITER: I have seen tests where it 3 actually goes up and it comes down. 4 CHAIRMAN WALLIS: Right, right. 5 MR. HOCHREITER: So, our prog;am objectives are to 6 basically build a separate effects test facility, riding on 7 the facility, where we can try to isolate different 8 phenomena that constitute disburse flow of foam boiling and 9 develop improved models from the data for this region, 10 integrate these models into a best estimate code, and then 11 verify the models. 12 Now, the program -- the rod bundle heat transfer 13 program is organized into 16 different tasks, okay, and 14 there's a bunch of reports that go to the NRC, including D _ (_,) 15 data reports, data analysis reports, modeling reports' and
+
16 so forth. Right now, we have planned two bundle builds in 17 the test facility. We have insulated the test facility very 18 well. We've got over 400 channels of instrumentation so far 19 and the number is going up. This program is different than 20 other rod bundle programs in the past, and that's been 4 21 question that other people have asked. And I've got a slide 22 to talk about this a little bit more. 23 This program is really designed for model 24 development. The other reflooding test.that we ran -- in 25 fact, I ran them, they were designed to look at margin r
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323 1 relative to Appendix K, okay. So the purposes were ( 2 different. L 3 DR. KRESS: .You're going to have measure droplet
" ~~
4' size and -- l 5 MR. HOCHREITER: Yeah. j 6 DR. KRESS: -- measure droplets and -- 7 MR. HOCHREITER: Yeah. Sex -- separate sex, 8 everything. ; i 9 DR. KRESS: -- sex, okay. 10 MR. HOCHREITER: We have several studies today and 11 quasi studies today to try to isolate phenomena. We're I 12 trying to use a building block approach here, because the l 13 dispersed phase while he transmits is very complicated. And 14 the program is five-year duration and we started not quite ('T ( ,/ 15 two years ago. 16 So, I'm going to go through the program task by l 17 task. The first task was developed a detailed PIRT for 18 reflood. So, what we did is we broke it into six areas and 19 then looked at the phenomena in each one of these areas. 20 And we tried to reduce it down to a component phenomena and 21 not have something that says reflood heat transfer. Okay, ; 22 that's not much use. So, we wanted to break it down.into 23 the components of reflood heat transfer, that a computer 24 code, like TRAC-M, would calculate and then use to get the 25 total heat transfer on the rod. f}'.
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324
'l This is just an illustration of the PIRT that we
() 2 came up for, for the disbursed phase, and this is my example 3 of breaking it down-into the components. The disbursed foam 4 boiling consists of convection, to see if we can get a. 5 vapor, disbursed phase enhancement.of the convection, direct 6 contact, heat transfer, drywall contact heat transfer, 7 droplet to enter, droplet interfacial heat transfer, and 8 more, and radiation heat transfer between drop, surfaces, 9 and vapors, okay. So, we tried to take the PIRT and bring 10 it down to a level, because a code like TRAC will have a 11 correlation or model to predict this. It doesn't have this 12 in there. It may or may not have this; may or may not have 13 this. Does have a model for this and it does have a model 14 for that. And we did this for each phase of reflooding. 15 CHAIRMAN.WALLIS: You are very bold. 16 MR. HOCHREITER: I'm sorry? . 17 CHAIRMAN WALLIS: You're very bold to undertake 18 such a complicated task. 19 MR. HOCHREITER: Yeah, I know. 20 [ Laughter.]
'21 MR. HOCHREITER: We did a critical literature 22 review. We looked at over 300 articles and reports. There 23 is a ton of literature in this area, okay. Most of the 24 bundled tests were performed in this time frame, even the 25 FLECHT/SEASET test. The blockage tests were done in like ANN RILEY & ASSOCIATES, LTD.
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I 325 1 1981, 1982. The objectives of the reflood tests, they're [G l 2 clearly to provide Appendix K model for given field designs. 3 Mostly open literature tests did not use mixing vane grids. 4 Our FLECHT/SEASET test did not use mixing vane grids. There 5 were some Westinghouse proprietary tests that did. There 6 are now some Siemens tests, which have used their mixing 7' vane grid design and so forth. 8 This makes a big effect. It tests around design 9 with the idea of developing the best estimate model, okay, ' 10 because of the time frame. They were really designed to 11 provide you a correlation to put into your Appendix K 12 evaluation model. It was very sparse or not used. The 13 FLEX-C set used some local instrumentation. 14 Now, after reviewing all of this, the existing rod f (},f 15 bundle data should be used for model verification. It , 16 should be used, okay, model verification, but not model 17 development, because you don't have enough global 18 information. So the gap that we're trying to fill here is l 19 the data for model development, then we could use.our data 20 and all the other data to verify the model. 21 The third task was to assess the code modeling 22 capabilities, validation assessment, and so forth. So, we 23 looked at a number of different codes. We put the code 24 models against the PIRT that we had developed. And we 25 compared those models and what we found was there were /^N ANN RILEY & ASSOCIATES, LTD. k-- Court Reporters . 1025 Connecticut Avenue,' M4, Suite 1014 Washington, D.C. 20036 (202) 842-0034
t i 326 l 1 models that were lacking, like space or grid heat transfer [ 2 models. There were models that had very large areas of 3 uncertainty, like this convected enhancement of disbursed 4 phase. And so, we factored the needs from the codes into 5 the test design, the types of tests --
)
6 DR. KRESS: You maintained -- 7 MR. HOCHREITER: Yes, I did. And the 8 instrumentation.
\
9 DR. KRESS: I was asking a question. I 10 MR. HOCHREITER: Oh, 11 DR. KRESS: You didn't mean that to be inclusive. 12 Those are just examples. 13 MR. HOCHREITER: Those are examples, yeah. 14 DR. KRESS: Oh, okay. 15 MR. HOCHREITER: The next task was to define the 16 objectives and I already gave that to you. 17 Okay, the next task was to develop a scaling for 18 the test facility. And unlike my tour of duty with the 19 AP600, where we did the scaling after the built the 20 facilities, which some people said it was probably 21 incorrect, we did.the scaling before we built the facility. 22- And we used the method by Dr. Zuber Wulff to basically 23 develop the scaling equations using the fluid energy, the
-24 rod energy, and the fluid equation. We calculated, defined 25 the pi groups. We normalized the pi groups for either PWR O ANN RILEY & ASSOCIATES, LTD.
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F l 327 1 or BWR, And what we were primarily interested in were 2 scaling distortions, okay. V['Y 3 And we found basically three scaling distortions 4 at the facility, primarily because of finite size and 5 materials. Okay, so there's a housing effect. This is a 6 small portion of a large rod bundle. All right, if you look 7 at it as a simulation of a boiling water reactor bundle, 8 it's a very good simulation; but if you look at it as a 9 simulation of a PWR, you can have additional radiation heat 10 losses that don't exist. So, we have to know about that. 11 The heater rod stored energy, we're using Inconel 12 clad rods with boron nitride material and it typically has 13 20 percent more heat capacity than a nuclear ro. And a 14 heater rod energy release rate, the boiling nitride 0) (_, 15 conductivity is quite a bit larger than the UO2 16 ' conductivity, so you'll get a more rapid heat release rate 17 at the quench front. 18 DR. KRESS: Is it important to model the 19- distribution of decay heat in this? 20 MR. HOCHREITER: You mean the axial power shape? 21 DR. KRESS: Yeah. 22 MR. HOCHREITER: It is and I'm going to show you 23 what the power shape is we're using. 24 CHAIRMAN WALLIS: Are you stuck with that? You're 25 going to do something to use some compulsive material, so lh ANN RILEY & ASSOCIATES, LTD.
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l l l l 328 l 1 you duplicate UO2 better or something? J t [)
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2 MR. HOCHREITER: The only rods I saw that had I
)
3 tried to do that were in the SEAFLECHT program that the ' 4 German's ran back in the 1980s. And the problem is you 5 introduce gaps. And if you introduce gaps, you don't know l 6 what the gap coefficient is and the gap coefficient will l l 7 vary during the transient. And so, if you try to reduce the 8 data to calculate the heat flux out of the rod, it becomes 9 very inaccurate. There are ways that we can deal with this. 10 We can deal with this; we're just going to have to live with 11 that, okay. 12 DR. SCHROCK: When you look at the housing effect, 13 are you going to look at the view factors that have been 14 used historically, simplistically? That is, near the quench ()s_- 15 front, you've got very sharp axial temperature gradients, 16 but they've always had in the codes nothing but view factors 17 for infinitely long isothermal surfaces. 18 MR. HOCHREITER: Right. Actually, near the quench 19 front, this -- the absorption of the heat by radiation 20 should be very small. It's going to be when you're.far from l 21 the quench front or you're heating the facility up, because 22 the temperature of the housing will be much lower near the i 23 quench front and the. temperature of the rods would be lower, 24 too. 25 DR. SCHROCK: Well, the temperature of the housing l [~\ ANN RILEY & ASSOCIATES, LTD. Court Reporters
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b i 329 1 ahead of the quench front -- I mean, there's going to be a
) 2 quench front on the rods. There's going to be a quench 3 front on the housing.
4 MR. HOCHREITER: Right. 5 DR. SCHROCK: And they may not match exactly 6 axially, but it's the same problem. i k 7 MR. HOCHREITER: That's right. l 8 DR. SCHROCK: Well, I didn't hear a clear answer ! 9 to it. I'm just suggesting to you that I've long suspected j
\
1 10 that those radiation calculations aren't worth very much, 11 because they have ignored the axial -- 12 MR. HOCHREITER: The axial component. 13 DR. SCHROCK: -- component, right. 14 MR. HOCHREITER: Okay. We can look at that. ( ,) 15 CHAIRMAN WALLIS: You are using water at the same 16 temperature pressure range and everything? l 17 MR. HOCHREITER: Yes. 18 CHAIRMAN WALLIS: It's the real thing? 19 MR. HOCHREITER: Yes. 20 CHAIRMAN WALLIS: And so, these are the only 21 things, which are really different. So, in many ways, it's 22' a full-scale test. 23 MR. HOCHREITER: From a geometry point of view, 24 yeah. 25 CHAIRMAN WALLIS: And, also, from a physical [ ANN RILEY & ASSOCIATES, LTD. \/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
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330 1 properties test, it's pretty well --
,s
! ) 2 MR. HOCHREITER: Well, the rod properties are %.) 3 going to -- 4 CHAIRMAN WALLIS: Yeah, the rod properties, but 5 the fluid properties -- 6 MR. HOCHREITER: The fluid properties are the , 1 7 same. 8 DR. KRESS: Are these 12 foot long rods? 9 MR. HOCHREITER: Yes. Single ended rods, so that
- 10. you can get a better simulation of the tie plate region. I 11 have some photographs that I'm going to show you.
12 We did the second tier scaling analysis and this 13 is where we concentrated looking at the local phenomena. 14 So, we set up radiation network methodology to calculate the () n 15 effect of a housing and we looked at a number of rows of 16 rods, okay. In other words, if you make the bundle 17 infinitely large, the effect on the housing diminishes. And 18 we picked, basically, a seven-by-seven bundle, based on 19 that, all right. It was probably the smallest bundle we 20 could go to where the center rods had a minimal affect of 21 the housing. 22 We, also, did a COBRA-TF detailed subchannel 23 model, which calculates radiation heat transfer and we 24 found,-actually, less radiation compared to our radiation 25 network calculation. And what we found was that the outer l') ANN RILEY & ASSOCIATES, LTD. \-s/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 1
n 331 1 rail rods are essential guard heaters, okay, and they () 2 actually protect the temperature in the inner five-by-five. 3 So, there's not a significant scaling distortion for the 4 five-by-five and we have a way of measuring its affect and 5 accounting for it, when we reduced the data. 6 We, also, looked at the heater versus the nuclear 7 rod. We set up a two-lumped parameter model and did 8 calculations for both heater rods and nuclear rods. And 9 this is where we found that the heater rod heat capacity was 10 larger and that the heat release rate is faster due to the 11 higher conductivity of the boron nitride. Now, this can be 12 accounted for in the experiments just by using a different 13 initial temperature. So, if you wanted to match heat 14 capacity for UO2 of the fixed temperature, you would run (("%
,) 15' these tests at a slightly lower temperature -- starting 16 temperature. This, we have to live with; but we can 17 calculate it, so we know what its results are on the data'.
18 We , also, had to develop and define the 19 instrumentation requirements. So the approach we used was 20 to use the PIRT, the PIRT identified at the high rate of 12 1 phenomena that we wanted to measure, and then we developed 22 an instrumentation plan that tried to either measure that 23 phenomena directly or allow for some calculation of it from 24 the test data. It, also, helped define the separate effects
)
25 test that we needed to run to isolate particular phenomena. l [\- ANN RILEY & ASSOCIATES, LTD. # D Court Reporters ' 1025 Connecticut Avenue, NW,~ Suite 1014 Washington, D.C. 20036 (202) 842-0034 b
332 1 Not everything that's in the PIRT can be measured, okay, and a
) 2 I can point some of that out, if you want; but, most things 3 can't, but not everything.
4 CHAIRMAN WALLIS: What about the flow regime? The 5 sketch that you gave us, it's rather hard to imagine 6 measuring everything. 7 MR. HOCHREITER: That's right. That's -- the 8 interfacial area, with the exception of droplet flow, 9 probably cannot be measured. So, we're going to have to 10 either infer from photographs, high-speed movies, gamma l 11 measurements for void fraction, delta-p span measurements 12 for void fraction, because that's probably the weakest 13 thing. 14 Now, some of our specific instrumentation
) 15 objectives and philosophies, which, again, is driven through 16 the PIRT, was we are going to be using finely-spaced 17 differential in the lower region of the bundle, where the 18 void fraction is lower, to get more accurate void fraction, 19 okay. And this is going to be in the quench and froth 20 regions. If I can find that figure --
21 CHAIRMAN WALLIS: The issue of void fraction is 22 the velocities are so low. 23 MR. HOCHREITER: Yes, the velocities are so low 24 and the acceleration term is low, the elevation term is the 25 dominant term. Now, we have to calculate that, so this [ ; ANN RILEY & ASSOCIATES, LTD.
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333 1 becomes kind of an interactive circle. So the region we're () 2 3 talking about putting more delta-p cells is in this region, in here, where the void fraction is lower. 1 Because, really, 4 what you're trying to get a good handle on and the key 5 uncertainty in most of these codes is the entrainment. All 6 its liquid is entrained, carried up, and then what's the
, l 7 form of the liquid, drops, chunks, what have you.
8 DR. SCHROCK: Are you going to try to model in any 9 way this periodic filling up of such large chunks, that 10 there's not enough interfacial drag to hold them up, they l 11 fall back again? You've got that kind of -- you said you've 1 12 seen it yourself. 13 MR. HOCHREITER: Yeah. Some of that -- I'll tell 14 you, some of that stuff -- this feeds into another figure.
/ 15 Some of what I saw was driven -- some of what.I saw was 16 driven by the pressure control on the test facility. And 17 for a forced convection test, it looked like it was a.
18 gravity reflooding test, because the pressure control was 19 trying to maintain a constant pressure and it couldn't, so 20 you had isolations in the pressure. I pleaded isolations in 21 the void fraction. It was throwing stuff up -- 22 CHAIRMAN WALLIS: The scaling, you have to do 23 something about the compliance of the rest of the system. 24 MR. HOCHREITER: Yeah, and I'm going to show you 25 something on that in a minute. The gravity reflooding, you (~D ANN RILEY & ASSOCIATES, LTD. \~ / Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 rJ b
l i 334 1 see it surge in and fall back. You do see that. But, it () 2 3 all falls back -- well, most -- it doesn't make it out. LR. SCHROCK: That's a little different than the j 4 phenomena that I'm talking about. I think we're -- it's 5 just periodically a slug that's too big goes up, there's not ; 6 enough interfacial drag to carry it on, and it drops back - j 7 - 8 : MR. HOCHRBITER: Yeah. 9 DR. SCHROCK: -- and sweeps up a lot of other 10 stuff with it. 11 MR. HOCHREITER: Yeah, it will fall back and then 12 it maybe sheared again and then maybe it's broken up into I 13 little small pieces and it goes up. I mean, that occurs in 14 this region. It can occur right in here. It depends on how () 15 much steam flow you have coming up here. 16 CHAIRMAN WALLIS: Your computer model to represent 17 this is for a one-dimensional model? 18 MR. HOCHREITER: It really is a one-dimensional 19 model. 20 CHAIRMAN WALLIS: So, it's averaging all this 21 stuff across the -- 22 MR. HOCHREITER: Yes, yes. Okay, the other thing 23 we're doing.that's strategy is we're going to put the heater 24 rod thermocouples at about the center of the delta-p spans 25 and, the reason for that is that we can correlate then heat
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l 335 1 t:ransfer versus void fraction. And Joe Kelly showed a j () 2 couple of slides at the last meeting where this program was 3 discussed and he had looked at data, and you could see that l 4 it was a clear -- there was a clear void fraction trend and 5 all the other secondary parameters, like subcooling liquid 6 flow, all those kind of stuff, tended to basically collapse 7 into a curve. 8 DR. KRESS: Are you actually going to measure rod 9 heat flux 7 10 MR. HOCHREITER: Yes. We're going to calculate 11 rod heat flux and we're going to measure rod temperature. 12 DR. KRESS: And have thermocouples in the middle - 13 - 14 MR. HOCHREITER: Yes. (Oj 15 DR. KRESS: -- and on the inside of the clap? 16 MR. HOCHREITER: It's on the inside of the clap. 17 DR. KRESS: Okay. But, you're going to get the i 18 heat flux out of that? ! 19 MR. HOCHREITER: Yes. We've done that before with 20 FLECHT. 21 DR. KRESS: That's our former member. It's been & 22 long time. 23 MR. HOCHREITER: We're, also, placing heater rod 24 thermocouples downstream in the spacer grids and the idea 25 there is to pick up the heat transfer enhancement that the
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1 336 1 spacer grids will provide for it. You don't have this in
/~s 1
(~/ ) 2 your handout, but this is Oak Ridge data a'1d every place you l 3 see there is a saw tooth is where a spacer grid is. l 4 DR. KRESS: Are you going to talk about new and 5 innovative grids to enhance the heat transfer? 6 MR. HOCHREITER: No. 7 DR. KRESS: Okay. 8 CHAIRMAN WALLIS: The industry might. That's the 9 industry's job. 10 MR. HOCHREITER: But, I'd like to test them. i l 11 DR. POWERS: Are grid spacers all using zircaloy 12 or are they still using -- l l 13 MR. HOCHREITER: All zircaloy in the center 14 regions of the core. I've got a picture of a grid that ( ,) 15 we're going to -- one of the candidate grids we're looking 16 at. What I wanted to do was to specifically caption this l 17 effect, okay. These lines -- some of these lines, this is 18 COBRA / TRAC -- COBRA / TRAC predictions. They have a spacer 19 grid model in there. Most of these codes don't. 20 The other thing we considered in our 21 instrumentation was to place heater rod thermocouples, vapor 22 temperature measurements, housing measurements, support two 23 measurements, such that we can run radiation only tests and 24 verify our radiation calculations. And we'll run these with 25 che test facility evacuated, so there's only radiation heat
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i 337 1 transfer occurring. So, we can predict the temperature () 2 distribution between the different rows of rods, if you 3 would, in the housing, and then we have a way of measuring 4 it. Of course, we'll actually distribute the thermocouples, 5 such that we can get the full axial quench behavior. We're 6 using miniature thermocouples to measure the non-equilibrium 7 vapor temperature. .And we put some of these on rakes, which 8 we can traverse the rod bundles, so we can get local 9 -subchannel values; and we've attached some to spacer grids, 10 so they will be permanently attached to a spacer. We will, 11 also -- 12 CHAIRMAN WALLIS: You can do that? 13 MR. HOCHREITER: I'm corry? 14 CHAIRMAN WALLIS: You can actually do that? () 15 MR. HOCHREITER: Yes. 16 CHAIRMAN WALLIS: And they are presumably hit by 17 droplets and things, so -- 18 MR. HOCHREITER: But, if they're very, very'small, 19 and these are very, very small -- 20 CHAIRMAN WALLIS: But, you did train the liquid - 21 - 22 MR. HOCHREITER: Well, that's why in a study state 23 test, I can use these traversing thermocouples, okay, 24 because I can take them through the flow and if I have to, 25 we've designed it so you can completely retract the O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 ,,
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l 338 f l 1 thermocouple out of the flow. ( () 2' 3 The problem is the transient test for the reason that you just said. 4 It's like you put more blockage into 1 4 the flow. So, we've run -- we've built a small three-by- l 5 three rod bundle and we looked at this effect and the effect 1 6 of the measuring device was small, because we made it as I I 7 small as we could. But, there still could be an effect. 8 CHAIRMAN WALLIS: Even so, it does get droplets l 9 hitting it and so on and so forth, l l 10 MR. HOCHREITER: Yeah. 11 CHAIRMAN WALLIS: Then, you dispense them? Or it; 12 evaporates them? Or what happens? i 13 MR. HOCHREITER: Well, they fall off. 14 CHAIRMAN WALLIS: Why doesn't it measure
'O
( ,/ 15 saturation all the time? 16 MR. HOCHREITER: Because, the void fraction is so 17 very high -- 18 CHAIRMAN WALLIS: I see. 19 MR. HOCHREITER: -- the probability of being hit 20 is small. And the thermocouples, themselves, are small, so 21 if they're hit, they quickly reheat, okay, a very low heat 22 capacity. As the froth front, where we have a low void 23 fraction mixture, starts to approach the thermocouple l l 24 location, you'll see more hits, okay, and you'll see a 25 ragged curve that slowly comes down to the saturation O ANN RILEY & ASSOCIATES, LTD. k/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 l (202) 842-0034 1
339 1 temperature. But when these things are more than two feet / 'h 2 above the quench front, they're going to measure vapor V 3 temperature and allowed to correct the measured vapor And we did that before in the'- 4 temperature for radiation. 5 FLECHT program and it was about a 25 degree correction at a 6 temperature of about 1,800 degrees. 7 DR. KRESS: Are you going to try and go in this 8 thing and study -- 9 MR. HOCHREITER: Yes. 10 DR. KRESS: -- where you have a fixed quench 11 front? 12 MR. HOCHREITER: Yes. 13 DR. KRESS: That would be interesting. 14 CHAIRMAN WALLIS: A fixed quench front doesn't 15 make sense. 16 DR. KRESS: I have a fixed amount of water that - 17 - 18 MR. HOCHREITER: I'm going to fix the quench 19 amount by not having one. That's how I know it's fixed. 20 CHAIRMAN WALLIS: Oh, okay, I see. 21 MR. HOCHREITER: And then, as I said, we measure 22 the grid temperatures. The grids do three or four things'to 23 the flow, all right. They will mix the convective flow, all 24 right. So, actually, you'll get an increase in the 25 convective heat transfer, so you tend to increase the vapor l' ANN RILEY & ASSOCIATES, LTD. 's-) Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 j
I 340 l-L 1- temperature. 1 ; l l [)
\_)
2 They will -- or can wet, and if they wet, the 3 grids have an amazing amount of surface area, okay. So, if l 4 you' cover all of that surface area with a liquid film and 5 then you go calculate the interfacial area now to somcthing 6 which is stationary and steam at 50 feet a second, ycu get a 7 tre7endous amount of desuperheating that occurs. 8 And the third thing is the grids break up the 9 drops and you generally wind up with a -- like a bimodal
)
10 population of drops, where you'll have very small drops and 11 the same size drops that were coming into the grids. 12 CHAIRMAN WALLIS: I think they're mostly 13 demisters. They might actually -- they build bigger drops. 14 That can go both ways, f3 15 MR. HOCHREITER: () The stuff I've done says they.get 16 smaller. 17 CHAIRMAN WALLIS: The grids are used sort of as 18 demisters. 19 MR. HOCHREITER: If the -- if the grid completely 20 wets, all right, then the entrainment coming off the grid 21 can give you a different drop size from what you might have 22 in the flow. But, normally, when you're turning around the 23' peak clouding temperature, the grids around that location 24 are dry. It's only at the lower elevations that they get 25 wet. Now, if you have these liquid surges that come into l 1 (~- ANN RILEY & ASSOCIATES, LTD. l
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, 9 :< >
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Li N 341 1 the bundle, like during gravity reflood, you may be able to
! ) 2 wet some of those grids. They may dry out, okay. We'll be 3 able to measure that affect.
4 DR. KRESS: Once you place these droplets through 5 one grid and it breaks them up, they won't continue to break 6 up for the next grid, will they? 7 MR. HOCHREITER: If they hit the grid and they hit 8 with a high enough velocity -- 9 DR. KRESS: Well, I thought it would be the change 10 in velocity and the change in turbulence that breaks them 11 up. 12 MR. HOCHREITER: No. 13 DR. KRESS: It's just colliding with -- 14 MR. HOCHREITER: I think it's just the mechanical p i _j 15 interaction. 16 DR. POWERS: But, I thought what you were saying, 17 if a droplet hits -- 18 DR. KRESS: It's going to break up to a smal3er 19 size, based on -- 20 DR. POWERS: When the smaller ones hit, they're 21 not going to break again. 22 DR. KRUSS: Yeah, that's what I was saying. 23 MR. HOCHREITER: If they hit the grid and they 24 have a high -- I've looked at correlating data, in terms of 25 a perpendicular Weber number, okay, only because that seemed ANN RILEY & ASSOCIATES, LTD. N - Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 c a t
F. 342 f 1 to be the right thing to do, at the time. And as you () 2 increase that Weber number, you continue to break up those 3 drops. Now, the probability of probably breaking up those 4 drops is reduced, because the best way to break it up is l 5 either on a vane or where the two grid straps intersect, 6 okay. If you have a larger drop, it's going to be easier to 7 break it up than'a small drop. But if a small drop hits 8 those vanes, I think it can break up. 9 CHAIRMAN WALLIS: There's the opposite, very fine 10 drops get deentrained by the blades and then the big drops 11 coming off the blades cause the damage to the next ones.
-12 MR. HOCIC.EITER : That's right.
13 CHAIRMAN WALLIS: That's the opposite that's g 14 happening. () 15 MR. HOCHREITER: That's right. 16 CHAIRMAN WALLIS: It must depend upon the 17 conditions. It's not a designed universal statement -- 18 MR. HOCHREITER: Well -- 19 CHAIRMAN WALLIS: -- it makes them smaller. They 20 can make -- 21 MR. HOCHREITER: Yeah, but you're postulating that 22 the grid is wet. If the grid is wet, I think that can 23 happen. If the grid is dry, I don't think it will happen. 24 That's why we have to measure the grid temperatures. i 25 The other thing that we're doing at facilities, 1 I ANN RILEY & ASSOCIATES, LTD. O- Court Reporters 1025 Connecticut Avenue, NW, Suite 3014 Washington, D.C. 20036 , (202) 842-0034 i 4
. _.w i
343 1 we're putting a lot of viewing windows for the whole life of I ,') 2 the facility, with the idea, basically, of being able to use v 3 different measurement methods to get a lot of void fraction, 4 drop size, drop diameter -- both drop size, drop diameter, 5 as well as distribution of drop size and drop velocities. 6 DR. POWERS: What do you use for window material? 7 MR. HOCHREITER: Quartz. We, also, have the 8 liquid instrumentation design, so that you can do a 9 transient mass and energy balance. If we measure the exit 10 flows, and, of course, we know the inlet flows, we measure 11 the exit steam and water flow, and we do that by going inco 12 a separator and using a close coupled tank to collect the 13 entrained liquid, we use the vapor temperature measurements 14 and known rod heat fluxes, we can do energy balance down the (_) 15 bundle to the quench front. Knowing the inlet flows, the 16 temperature, and, again, the power, we can do energy balance 17 up to the quench front and they should agree. 18 We did this in FLECHT and it worked out reasonably 19 well. The problem we had was we didn't have enough vapor 20 temperature measurements. 21 DR. SCHROCK: How does this gamma x-ray 22 spectroscopy work? 23 MR. HOCHREITER: I'm going to show you that. 24 Okay, the eighth task was to develop a facility input model. 25 And we've done that and we're using COBRA-TF. And we have a
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344 1 two-channel model and, again, we have a detailed subchannel () 2 3 model that we've been using for doing pre-test predictions, to try to scope out the range of conditions for the 4 facility. 5 To develop a draft test matrix was the next task. 6 What we've done is we've tried to give the range of the 7 facility, fix that first, and then look at different tests 8- that we're going to run and then different conditions for 9 each series of tests. So the types of tests we're going to 10 run are going to be single phase hydraulic experiments. 11 We're going to characterize basically the pressure drop in 12 the facility, so we'll get the lost coefficients for the 13 grids correct. Now, if there's a change in the friction 14 packet for the rod bundle, we account for that, what have () 15 you. 16 We'll, also, do heat loss experiments, again, to 17 characterize the housing heat loss. Now, you need this 18 information to set up a code model for the facility, if you , 1 19 want to reduce your uncertainty in predicting these tests. 20 So the objective here is try to reduce that uncertainty. 21 We're going to be doing radiation tests -- 22 radiation heat transfer tests in the evacuated bundle. By 23 evacuating the bundle, we don't have the confusion of 24 reconvection inside the bundle, all right. So, we're going 25 to evacuate the bundle and we'll look at rod for rod around ANN RILEY & ASSOCIATES, LTD.
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345 1 the housing heat transfer. Independently, we've sent I
; 2 samples to be analyzed to get the emissivity. We have run 3 test rods over the number of cycles that we plan to test 4 these heater rods in the rod bundle and we cut up the rod, 5 sent them to Purdue, had Purdue measure the emissivity. So, 6 we can use those measured values of emissivity when we do 7 these calculations, rather than dialing in the emissivity to 8 match the temperature distribution.
9 DR. POWERS: What does the emissivity going to 10 measure for? 11 MR. HOCHREITER: For the ends of the rods, which 12 have very low duty, it was like about .5. 13 DR. POWERS: No, I mean -- 14 MR. HOCHREITER: I'm sorry.
) 15 DR. POWERS: Are they measuring just by total 16 hemispherical maintenance?
17 MR. HOCHREITER: I think that's what it was. It's 18 total hemispherical emissivity. 19 DR. POWERS: So, you don't have independence on 20 it? 21 MR. HOCHREITER: No , no. 22 DR. POWERS: That's kind of bad. 23 SPEAKER: It's not directional? 24 DR. POWERS: Emissivity kind of varies as a 25 functional weight length, especially if you've got an oxide
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- 346 1 on the surface area. I
. 2 MR. HOCHREITER: Well, yeah, but we've sent them 3 oxidized samples.
4 DR. POWERS: Yeah, so they'll have a weight length 5 dependence, i 6 MR. HOCHREITER: We'd better check on that. l 7 DR. POWERS: I mean, typically, outsides do and 8 they ought to have a -- as you pull down in energy, the '2 9 emissivity ought to go up. I i 10 MR. HOCHREITER: Go down in energy? 11 DR. POWERS: Yeah, as you move toward the 12 infrared, you'll cut through the -- 13 MR. HOCHREITER: We did -- we got a total l 14 emissivity measurement. We did not get a wave length or a (' 1 ( ,)f 15 spectrum measurement. Maybe that's something we better look 16 at. 17 DR. POWERS: It might be interesting just to see 18 what the spectrum is. I mean, what the literature says -- 19 MR. HOCHREITER: Well, .they can probably.- ' ? ' 20 DR. POWERS: -- it has, I don't know. 21 MR. HOCHREITER: They can probably do that. We 22 just.-- we weren't smart enough to ask for it. 23 DR. POWERS: Well, it makes a difference, because 24 you s re emissivity becomas a function of temperature. 25 MR. HOCHREITER: Oh, I see. Okay, let's -- we'll r j ANN RILEY & ASSOCIATES, LTD. k s/ Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 4
i 347 1 look at that. We're, also, going to run single phase steam
's m I
- 2 convection tests over the range of conditions and this is 3 roughly the range of Reynolds numbers that we're going to be 1 4 running over. You can reach laminar flow in these low 5 flooding rate experiments and calculations, because the 6 steam super heats so much, okay. Really, the Reynolds 7 number is proportional to one over the vapor temperature 8 squared.
'9. Now, having run these tests, we're going to run 10 single phase tests -- single phase steam convection tests, 1
11 where we now have a droplet injection method. And we'll i 12 inject drops in the bundle, in the interior of the bundle, I 13 and then we can measure the vapor temperature, the heat 14 transfer changes, and so forth. This is to try to get a
]
() 15 better handle on the convective enhancement due to the 16 drops. 37 DR. KRESS: Are you varying that drop size in the 38 injection?
9
. MR. HOCHREITER: Yes, you can, because we'll 20 change the injector size, okay. Then, we're going to run 21 force reflooding tests, but these will be run a little bit 22 different, because we're going to try to preserve some 23 conditions --
24 CHAIRMAN WALLIS: You're going to do analysis as 25 you go along -- in those kind of tests, you're going to ANN RILEY & ASSOCIATES, LTD. f)h x Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington,'D.C. 20036 (202) 842-0034 o
348 1 actually do some concurrent analysis development? [ U} 2 MR. HOCHREITER: Absolutely. We already have -- 3 like, we have a model here. 4 CRAIRMAN WALLIS: But, you'll be developing 5 another to do the test? 6 MR. HOCHREITER: We already have a model. 7 CHAIRMAN WALLIS: I hope you will get it all 8 together. It's tons of data, then look at it and say -- 9 MR. HOCHREITER: No, no, no , no , no. We have -- 10 we have developed -- we can predict this now, all right. 11 I'm not too sure how well, because we don't have the data
- 12. yet, but we can do this prediction. We can predict the 13 convection. We have a model correlation for steam that we 14 use, okay. So, we can already do these calculations.. We're O
; 15 doing these calculations now, single phase. We have a model s
16 for convected er.hancement in disbursed two phase flow. The
- 17. scatter on that model is at least a decade, okay. And, of 18 course, COBRA-TF has a "reflood" heat transfer models. So, 19- I mean, we have models.
20 What we're trying to do is what do we have to do
-21 to get better models. I view this in two fashions here.
22 Finding models or putting into the code models that don't 23 exist'and in trying to reduce as much as possible the 24 uncertainties for those models, which we think the phenomena
.25 is correct --
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I' 1 349 L 1 CHAIRMAN WALLIS: The ideal world, you make enough (~) 2 measurements to check all of the features of the model and
%.)
3 you.can tell that your -- 4 MR. HOCHREITER: Right. 5 CRAIRMAN WALLIS: -- x-ray measurements are going 6 to be used to check this path and the site measurements and 7 you see the coupling between them and you can tell if you 8 have enough measurements to check enough features of the 9 model, not too many -- you can adjust without enough 10 knowledge and all that sort of stuff. 11 MR. HOCHREITER: Well, that's kind of how we 12 developed the instrumentation plan. And in this, I'm going 13 to talk about a peer review report. In that peer review 14 report, we , again, go back to the peer -- sorry, go back to (O) u ./ 15 the PIRT tables that list the phenomena and then we put down 16 our assessment of how the measurements would measure that 17 phenomena. Some of these things we cannot measure, some can 18 be inferred, some can be capsulated from the data, and then 19 some can be directly measured. So, we've tried to go 20 through that exercise, okay. But, we can't measure 21 everything. I 22 We are going to run simulate -- so, we're going to
'23 run force reflooding experiments and then variable flooding 24 rate experiments, and this would simulate the response on 25 the inlet flow rate.
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350 1 Okay, we had to, obviously, design the test () 2 3 facility. Okay, we based the test facility design on the FLECHT/SEASET, the ACHILLES experiments, which were done in 4 the U.K., and the FEBA experiments, which were done over in 5 Karlsruhe. We provided ample view ports, so we can view the 6 flow of the transitions, look at the effects of spacer 7 grids, provide locations for local measurements. And we've 8 got a detailed instrumentation plan that I've talked about 9 and we're up to 414 channels and counting. 10 One of the tasks that we had to perform at the end
.11 of task 10 was to write basically a peer review report to 12 the NRC that documented the results of task one, which is 13 the PIRT, through task 10, which was the design of the 14 facility. And we have written that report. The NRC sent it
() 15 out for review comments to these individuals. We've gotten 16 comments back from them. We have integrated that back into 17 the peer review report and that report will eventually be 18 issued as a NUREG report. And it's a sizable document. 19 It's one of those sumo reports that Dr. Zuber likes to talk 20 about. 21 We, also, had an independent peer review of the 22 instrumentation plan here, and these are the gentlemen that 23 were involved in that peer review. 24 MR. BOEENERT: Larry, what is the schedule for 25 issuing that peer report?
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351 ) 1 1 MR. HOCHREITER: Probably sometime this fall. I {
/N 2 don't see Dave Besette here. We're waiting on some of his ~-
3 comments. J 4 DR. POWERS: Just glancing ahead in your view 5 graphs, you spend a little while looking at droplet sizes. I 6 MR. HOCHREITER: Right. j 1 7 DR. POWERS: Do you have any kind of light l 8 scattered techniques that you're using? I 9 MR. HOCHREITER: Yes; yes. Okay, task 11 is to 10 construct the facility, okay. Well, construction has begun. 11 We've gotten heater rods. We designed a long life heater l 12 rod. This is a major cost. These heater rods are $8,000 13- each. 14 MR. BOEHNERT: How much? [J A
} 15 16 MR. HOCHREITER: Eight thousand dollars, okay.
'And the first -- the first prototype that we got, we melted.
'17 So, we didn't think that was too good. So, we had to go 18 back and take a look at how we ran the test and that helped 19 u s '.
, 20 We've gotten some of the rods -- the final rods. 21 They're at Penn State. We're beginning to inspect them. 22 We're going to add over the last of the components. Most of 23 the tanks have already been purchased and so forth. We're 24' ' building a building at the university to put this thing in. 25 And~that's -- the bids have been received. They're going to
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p 352 t i start digging it up probably in the next few weeks. ()
\ss/
2 DR. KRESS: Who did you buy your heater rods from? 3 MR. HOCHREITER: From Stern Labs in Canada. We 4 went out for bids, okay, and there were really -- it started
-5 off with, I think, three or four and two of them quickly 6 dropped out, because of the requirements that we had.
'7 Remember Reg?
8 DR. KRESS: Yeah. 9 MR. HOCHREITER: He bid on them and he' bid a very 10 low price, which scared us, because he had never' built rods 11 like this. Stern Labs had built labs that were used at v 12 Siemens, and so we talked specifically to Siemens and got 13 their performance information. And they performed very 14 well. 15 f( ) DR. KRESS: Do they have spiral wires? 16 MR. HOCHREITER: It's a ribbon that's cut. 17 DR. KRESS: Oh, it's a cut ribbon -- l 18 MR. HOCHREITER: Yeah. 19 DR. KRESS: -- with different widths.
'20 MR. HOCHREITER: Different widths.
21 DR. KRESS: Okay. 22 MR. HOCHREITER: And I'll show you a power shape 23 in a minute. We have to write a design report after it 24 started and we're' hoping to be testing in next May. Now, of 25 course, the first tests we're going to run are going to be (1- ANN RILEY & ASSOCIATES, LTD.
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353 1 the simplest ones. We've got to characterize the facility, 2- like I said, measure pressure drops, get volumes right, all 3 this kind of stuff. That information will go into the 4 design report, so a cold -- not cold modeler can go ahead
- 5 and then take all of the information.out of the design 6 report and set up a DUCK.
7 The twelfth task is define the test, initial 8 environment conditions. What we're going to be doing is 9 using COBRA-TF calculations and, also, we'll be overlapping 10 with the FLECHT/SEASET test. Then, we'll perform the test, 11 quality the data, and to the reporting. We've already 12 started writing data reduction and analysis programs to do 13 this, using, in many cases, what was already done in 14 FLECHT/SEASET, at least the form, okay. We haven't analyzed
/*'*\
15 tG any data, because we don't have_it yet. 16 Now, new or modified mcdels: one of the things 17 we've done is we've taken the heat transfer package from
- 18 COBRA-TF and we put it into a standalone assessment method, 19 such that we can more easily go in there, change models, and 20 . play with it. We're going to do the same thing with the 21 . interfacial package and for interfacial drag in COBRA-TF.
22- And then the final task is basically to report 23 everything: 'the data, the analysis, the models, and the 24 . implementation. j 25 CHAIRMAN WALLIS: Is the implementation going to l 1 ANN RILEY & ASSOCIATES, LTD. f Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
354 1 be in the form of modules, because you can be plugged right 2 into TRAC code? 3 'MR. HOCHREITER: That -- yes, that's the idea. l 4 So, when we approach this, we have to approach it from the l 5' knowledge of what TRAC needs.
)
6 Now, let me show you what the facility is going to 7 look like. Again, it's a 49 rod bundle. We have 45 heated - j 8 rods and four corner rods, which are unheated. We've got a , 9 lot of windows. We're going to be using prototypical mixing 10 vane grids and it's going to be well instrumented to 11 measure, of course, wall temperatures, for the heater rods, 12 the housing, and the grids. We're going to be able to 13 measure either the vapor temperature or the liquid 14 temperature of the fluid with miniature thermocouples, i 15 We'll be measuring drop diameter and drop velocity 16 distributions using a laser illuminated camera system. 17 We've built a three-by-three heated rod bundle roughly four 18 feet high-to verify that this thing would work. 19 We're looking at, again, finally spaced delta-p 20 cells for void fraction measurements, either a gamma ray or 21 an x-ray technique. We can get a hold of some gamma ray 1
'22 detectors free. Nothing is really free, but these are just ;
23 a little more free than other things, okay, because we would 24 have to supply some electronics. But, these are detectors 25 that were used, I believe, in the FIST test that are out in I'\ ANN RILEY & ASSOCIATES, LTD. V Court Reporters 1025. Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 L (202) 842-0034
355 1 n Idaho. 2 This is a technique, and I've got a slide on this, 3' this x-ray technique is basically using a low energy x-ray 4 machine that generates photoelectrons, which will give you a 5 picture of the void fraction. And, again, we built a bench 6 test and tested this, and this looked reasonably well. Of 7 course, we're going to measure the steam liquid flows, the 8 unit flows, and the grid temperatures, as well. 9 DR. SCHROCK: Can I ask -- 10 MR. HOCHREITER: Yes. 11 DR. SCHROCK: -- about your word " spectroscopy" 12 there. Before, you said you were going to tell us about 13 that. 14 MR. HOCHREITER: I am. () 15 DR. SCHROCK: Not here, though, all right. These 16 don't impress me as spectroscopy so far. 17 DR. POWERS: I've used x-rays to get 18 photoelectrons to look at, one, behavior and dynamic 19 situations, and it works amazingly well. 20 MR. HOCHREITER: Yeah. 21 DR. POWERS: I mean, it surprised the hell out of 22 me. 23 MR. HOCHREITER: Somebody else is doing this. 24 This is not my baby. This is the rough schematic of the 25 facility. Basically, we can bring the steam flow in here. [} (. / ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
356 [ 1 We can bring water in here. We have a down cover, if we [~' 2 want to run gravity tests. This tank is very close coupled V)' 3 to this, so that we can collect the water and measure it 4 quickly. We go into the phase separator, collect the liquid t 5 here. j 6 This is the pressure damping tank. This is one of j l i 7 the things we found in the literature from the ARCHILLES J 8 test facility. Now, using a tank like this and then 9 controlling the pressure here, this tank has sufficient 10 capacity that any cycling of the valve didn't feed back on 11 the te c, and so you can truly maintain a constant pressure. 12 This will be our injection system for water. 13 The next schematic, ic chows -- and this is, by no 14 means, obvious instrumentati_: - a lot of the () 15 instrumentation in the test facility. These are the wall j 16 temperatures and, of course, there's a whole bunch of delta- l 17 p cells. One of the nice things about being at a university 18 was the guy from Rosemont Fisher came around and he ,,us a 19 Penn State grad and they sell delta-p cells -- they make and 20 sell delta-p cells. We were able to convince him, without 21 the additional benefit of giving him football tickets, that 22 he should give us our delta-p cells at a reduced cost. The 23- company cut the cost in half. 24 DR. POWERS: What would they be with the tickets? 25 MR. HOCHREITER: I'm sorry?
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E 357 1 DR. POWERS: If you had given tickets, what would
/
'T 2 they have done?
L) 3 MR. HOCHREITER: I think we probably could have 4 gotten them for free. I don't have the tickets. 5 DR. POWERS: Talk to Joe. l 5 MR. HOCHREITER: This is the test facility.
;7 Again, it's a square housing, Inconel tubing. These are the l
8 windows up there. Of course, this is the rod bundle. This ; 1 9 will be in the lower plenum and it will set the flow l 10 conditions coming in here, and the upper plenum is what we 11 use to basically collect and separate out the liquid and the l 12 steam and they will also go into a separator to separate it 13 out further. 14 CHAIRMAN WALLIS: How well can you see the
,m (GI 15 interior of this bundle?
16 MR. HOCHREITER: Well, you're looking through a 17 .122 inch gap, okay. That's what you're looking -- because 18 you're looking between the rods. You can see through. 19 CHAIRMAN WALLIS; You're looking through several 20 gaps to look all the way through. 21 MR. HOCHREITER: That's right. Now, a problem can 22 occur, which is rods can bow. Now, we're trying to consider 23 that in the design. And usually -- I mean, the most 24 difficult calculations here that we've had to do our more 25 mechanical calculations -- s
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358 1 CHAIRMAN WALLIS: And the spray is splashing on
/~~'\ '
2 the window at the same time? N-) l 3 MR. HOCHREITER: We're going to heat the windows. j 4 CHAIRMAN WALLIS: Keep them dry? 5 MR. HOCHREITER: Keep them dry. 6 CHAIRMAN WALLIS: Heat them enough to keep them 7 dry? 8 MR. HOCHREITER: That's what we're going to do, I 9 infrared heating -- either infrared or clamped on heaters 10 that you take off when the test begins. Now, I don't think 11 I'm going to -- 12 CHA'RMAN I WALLIS: You're going to be testing 13 window crunching is what you're going to be doing. l 14 MR. HOCHREITER: Well, I don't -- that's what I (x t V) 15 don't want to do. So, these windows are probably going to 16 crunch no matter what I do, all right. It's these windows 17 up here, particularly this one, all right, because when 18 you're getting your peak planning temperature up in here, 19 it's for this -- the froth from it is starting to move into 20 this window. So, I want to keep that dry. You don't think 1 21 so? ' 22 DR. POWERS: You're going to pass the pressure l i 23 safety in that -- 24 MR. HOCHREITER: We never gave it to them. This 25 is actually.-- what we did do -- seriously, is what we did ('N ; ANN RILEY & ASSOCIATES, LTD. (,/. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 ! (202) 842-0034 i
I ) L 359 l 1 was we did a finite element analysis on this housing, okay, (} 2- and that's what determined what the thickness was, okay. I { 3 was trying to get a 3/16th inch thick housing. And we're 4 just too close to the limits in the areas where the windows 5 were, so.we had to go up to a quarter of an inch. But, we i 6 did do a detailed finite element analysis with an imposed 7 temperature distribution on it. We, also, had to worry 8 about fatigue, as well, because you're going to heat it, 9 crunch it -- 10 CHAIRMAN WALLIS: Who is going to -- 11 MR. HOCHREITER: I'm sorry? He is. I'll be back 12 in my office. No , I've done this. I've done this. I've 13 looked in these windows. It scares the hell out of you. 14 This is the cross section -- I'm sorry? () 15 DR. SCHROCK: The windows are quartz? 16 MR. HOCHREITER: Yes. 17 DR. SCHROCK: And how high of water temperature 18 that you have there? 19 MR. HOCHREITER: Kater temperature? 20 DR. SCHROCK: Yeah. 21 MR. HOCHREITER: The water temperature will be 22 about 240 degrees. 23 DR. SCHROCK: Not very high, yeah. l 24 MR. HOCHREITER: I don't think it's the water, 1 25 it's the steam. The steam can be 1,500 degrees. i f ANN RILEY & ASSOCIATES, LTD. ( Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 ('02) 842-0034 i L.
I' 360 , 1 DR. SCHROCK: Sure. And I was just thinking of l
-2 the etching problem.
- 3 MR. HOCHREITER
- Now, that's a concern. We are l
4 aware of that. In fact, we had a ruby layer over quartz and 5 we may have to go so sov.ething like that. 6' This is the rod bundle cross section. These are 7 all powered rods. These simvlate guide through thimbles 8 from a space point of view inside of a fuel assembly. 9 Typically, 10 percent of the rods in the fuel assembly are 10 guide through thimbles, in a Westinghouse or BMW fuel 11 assembly. What we use these for is, first of all, support; 12 and then we, also, bring out instrumentation, because we're 13 going to have grid thermocouples to be able to come out 14 through here. We, also, have these miniature steam probes () 15 and they will have to come-out through here. And, of 16' course, we'll have thermocouples on those. So, when you do 17 a radiation calculation, you've aligned the instrumentation 18 that we will get a measured temperature across the bundle 19 and then we can compare that to our calculations. ! 20 This is a shot of the windows. We made these ! 21 things.large, okay, 11-1/2 inches. And the reason is this l 22 is where a spacer grid will sit. We wanted to be able to i 23 measure the drops coming into a spacer grid and the drops 24 going out. Now,.we have these bracketing all the spacer i 25 grids. Now, we have built a fixture like this. The concern i O (,,/ ANN RILEY & ASSOCIATES, LTD. Court Reporters i 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 m
361 1 - the design concern was a seal and we've been able to show () 2' 3 that it will meet the pressure requirements. Dr. Griffith, when he looked at this,. told us exactly where it would leak, 4 which was right in here, and so we're going to change the ! J 5 torque loading on the bolts to account for it. 6- This is the power shape we're using. This is 7 different than what's been in previous FLECHT test. In 8 FLECHT test, we tyy,>ically had 1.66 cosine. This curve came 9' from looking at a bunch of best estimate calculations and 10 looking for limiting power shapes. Typically, what you 11 find, if a plant is reflood limited, using a best estimate 12 technique, the peak is above the midpoint, okay, because 13 you're just increasing the distance of the quench front. 14 So, you get more distance to super heat the steam when the () 15 cooling is simply poor. This is just a simpler drawing, if 16 you would, of a different power shape, i l 17 CHAIRMAN WALLIS: It seems to me, you want to turn 18 them around, because you only get some of the power shape to 19 check -- 20 MR. HOCHREITER: Well, there is data with 21 different power shapes. There is data with different -- 22 CHAIRMAN WALLIS: The problem is you have to feed 23 down the bottom -- 24 MR. HOCHREITER: That would be your -- 25 CHAIRMAN WALLIS: This is for a model development; kI
/'
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362 1 this isn't for -- so, you need some variation of that, it
) 2 would seem.
3 MR. HOCHREITER: Well, like I said, there are -- 4 there is other data out there, okay. There is the FLECHT 5 and FLECHT -- the FLECHT set 15 by 15 data that has a peak 6 here and 1.66 is the cosine. There's the FEBA data that has 7 a peak at the midpoint of 1.9, flat cosine. There's the 8 CCTF data and the SCTF data that have a, again, flatter 9 cosine with a peak that's 1.4. And there's the FLECHT 10 skewed test that had a peak at the 10 foot elevation up here 11 of 1.35. So, there are a number of different experiments 12 that have different power shapes. None of them have the 1 13- instrumentation that we're putting in with this stuff. So, 14 my -- back to one of my earlier slides, this test is to () 15 develop a model base, okay. You should then take that model 16 base and you should compare it to these other experiments, 17 because there's enough information in those other l 18 experiments to know if you're doing well or not, .primarily 1 19 temperatures. 20 This is the grid that we're designing right now. 21 This is sort of based on a Westinghouse grid. Westinghouse 22 sent us some drawings, which had, of course, the minimum 23 amount of information. It said things like, it's made out 1 i 24 of metal. 25 (Laughter.] i O ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
E i 363 1- MR. IiOCHREITER: But, we're right now designing l l 2 this. There's a company that will build these. We've 3 received some interest from ABB Combustion Engineering. 4 They would like to run tests in our facility with their l 5 spacer grids for many of the reasons that we talked about 6 this morning. There's a margin to be gained if you use 7 product specific spacer grids, because that's exactly what 8 they do for DNB and you would expect to get some more 9 benefits during reflood when the heat transfer is low, okay. 10 If the heat transfer is low or the flooding rate into the 11 core is very high, the effect of the grid is much smaller. 12 It's when the heat -- when the flooding rate into the bundle 13 is very low, like one inca a second or so, which is typical 14' of what you calculate these days, even with the best 15 estimate code. You still calculate low flooding rates. 16 CHAIRMAN WALLIS: What are these little spiky 17 things? Is it some sort of spring -- 18 MR. HOCHREITER: They are a vane -- they're a 19 vane. They're designed -- the purpose of the vane design is i 1 20 to strip off the bubble air, mix the bubble air into the 21 subcooled'section portion in between the rods and the 22- subchannel. Tom was -- Dr. Tom was the first one that 23_ developed these' things. And what you try to optimize in 24 your design in thermo performance versus pressure drop. I 25 mean, you pay a price to do this, to mix the flow like this, T ANN RILEY & ASSOCIATES, LTD. O, Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C 20036 (202) 842-0034
l t 364 1 okay. 2 CHAIRMAN WALLIS: You put some swirl in this rod?
}
3 MR. HOCHREITER: Well, this was for overflow. 4 These vanes are at an angle, so they swirl the flow. The l 5 Siemens design has an.interflow channel in here that comes 6 up and bends as it exits the grids. So, some of the fluid I 7 goes in there and bends, so it swirls. l CHAIRMAN WALLIS: 8 How is your model going to put 9 that in? The model doesn't really have those kind of l 10 mechanisms in it, does it? 11 MR. HOCHREITER: No. Right now, we have a very l 12 simple model for this and what we look at is the amount of 13 blockage -- perpendicular blockage that the grid causes. 14 The vanes add blockage area, okay. And that can be used, () 15 then, to calculate a number to enhance the convector heat 16 transfer. The amount of blockage is used to determine what 17 fraction of the drops, which are entering the grid, can 18 break. And then, you worry about quenching the grids by 19 calculating the grid temperature. 20 CHAIRMAN WALLIS: I still think that this figure 21 looks more -- it's an optical illusion, I think. They're 22 not as complicated as they look, because they're a -- 23 MR. HOCHREITER: Yeah, there are some really l 1 l 24 worse. I have a colored picture here. J l 25 CHAIRMAN WALLIS: Why don't these vendors make j (~ ANN RILEY & ASSOCIATES, LTD. ( Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 f (202) 842-0034 i l 6 l
- f. 1 l
i 365 1 things that you analyze it for? i l' \ 2 DR. POWERS: Because, they don't care. O t 3 DR. SCHROCK: They don't care. 4 MR. HOCHREITER: You're right. You don't want to 5 analyze. What you want tx) do is you want to get good data, 6 correlate -- get good data, correlate it very well, and use l 7 an empirical correlation. That's -- the problem with that, 8 of course, is if you change your fuel assembly design, 9 you're back to testing. I 10 DR. POWERS: But, testing on this code thing is 11 probably cheaper than any kind of analysis you can do, and I 12 it works.. I 13 MR. HOCHREITER: It works. It's not cheap. 1 14 DR. POMERS: It's not cheap, but it's cheaper than () 15 the analysis. It's a complicated thing to analyze. 16 MR. HOCHREITER: Well, I don't think there's 17 anyway in the world you would convince anybody that you can l l l - 18 analyze it, all right, or the uncertainty would be so large l 19 in the analysis that you'd have to test. But, let me tell 20 you, these DNB tests are expensive. 21 CHAIRMAN WALLIS: That could be argued about your l 22 whole program is, that you've got so many mechanisms in 23 here, that you might be better off to just test under all 24 possible conditions and correlate the answer. 25 MR. HOCHREITER: Well, that was done in the 1960s, 1 l . ANN RILEY & ASSOCIATES, LTD. Lk-)T s Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034-
i 366 1 1 '70, and '80s. 2 CHAIRMAN WALLIS: That's why I said you were bold 3 early on. You actually -- you have a hope here that by I 4 looking at enough information, you can get a physically 5 based -- which is adequate enough and doesn't have 50 dials, 6 which can be adjusted, so that your physics disappears. 7 MR. HOCHREITER: I wasn't joking before when I 8 talked about those correlations. I came up with a reflood 9 heat transfer correlation that had 12 variables and 13 10 points. 11 DR. POWERS: Unbelievable. But, if you came in 12 here and said, okay, we've got this totally empirical mc; del , 13 that we've tested 10,000 times, we'd throw heavy objects at 14 it, j () 15 CHAIRMAN WALLIS: Not necessarily. 16 MR. HOCHREITER: This is just a schematic of the 17 drop of injection scheme. What we're going to be doing is 18 injecting water in these subchannels, okay, so that we know 19 an inlet size drop size distribution, and then we'll be 20 measuring the change in the drops sizes, the change in vapor ! l 21 temperature, the heat transfer on the rods downstream of 22 this. And we'll do this for at least two drop sizes. 23 This is the traversing micro thermocouples. 24 Again, we'll have three thermocouples on a rake that looks 25 like this that we can insert into the bundle. We tested [~h ANN RILEY & ASSOCIATES, LTD. (_-) Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 I I
367 1 this in our three-by-three heated bundle and it workc fine.
/~N 2 You'd be surprised -- maybe you wouldn't be surprised, but
.3 there's a huge temperature gradient between the subchannels, 4 between the gap in the center of the subchannel, a very 5 large temperature difference.
6 DR. KRESS: That's what makes your rods bow. 7 MR. HOCHREITER: I'm sorry? 8 DR. KRESS: That's what makes your rods bow. 9 MR. HOCHREITER: Yes. 10 CHAIRMAN WALLIS: Are your rods going to bow? 11 MR. HOCHREITER: No. Actually, we ran -- the 12 concern really is how loose you make the grids. The rods 13 are supported at the top with a plate. They screw into a 14 plate. And the spacer grids are just there to keep them () :u5 16 from wandering all over the place. So, they -- when it's cold, they accually rattle inside the grids. And then when 17 they're heated, they just don't rattle as much, because you 18 don't want to have the grids binding the rods, forcing them 19 to bow. 20 Now, this. test program is not supposed to be 21 looking at temperatures that are all the way up to the 22 licensing limit, 2,200 degree Fahrenheit. But, we are going l- 23 to be running tests up to 2,000 degrees, okay. Steel melts L 24 at about 2,500 degrees. So, hopefully, the way we've 1 25- designed this thi.ng, we should not have bowing. Now, of p/. g_, ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 l i
i 368 1 course, we can see it through the windows. And our { 2 measurement system looks at more than one gap, okay. So, 3 that if we were to get bowing when you start to close off a 4 gap, we can move the measurement system to another string of 5 subchannels. 6 CHAIRMAN WALLIS: So, you have 45 rods at 8,000 7 bucks a piece?
-8 MR. HOCHREITER: 'Right. I'm going to be passing a 9 hat around here at the end of the presentation for 10 donations.
11 DR. SCHROCK: Your thermocouples are not cheap are 12 they? 13 MR. HOCHREITER: Well, it's the technology. What 14 'we've tried -- you know, to really try to address your () 15 question, this is why we've done things like made the 16 housing out of Inconel, the sheaf of the rods out of 17 inconel. The thermocouples that are inside the rods are 18 Inconel sheath, so that you minimize differential expansion 19 as much as you can. But, there is going to be large 20 temperature differences between the rods and the housing. 21 So, we've tried to account for that. We've had to account 22 for that when we chose the thermocouple locations, because 23 we're trying to measure an effect' downstream of a grid. But 24 during a test, the bundle assembly will move, just due to 25 thermo expansion. So, we've gone through those calculations (") (_,/ ANN RILEY & ASSOCIATES, LTD. Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
F 369 1 and we've picked the elevations the best we can. ( ) 2 But, these probes, again, tested these in the 3 three-by-three rod bundle, where we just blew hot air up 4 through'there and injected water droplets and these worked 5' ' fine. And I've used something like this in the 6 FLECTH/SEASET 21 rod bundle program. The beauty of these 7 probes is we can retract them completely out of the flow. 8 Running a study state test, I can go ahead and put them in 9 there and then not worry about things downstream, because I 10 can then retract the probe, then take the measurements 11 downstream. It's when I run the transient test, I probably 12 am not going to want these things in there. So what I have 13 to do is have, again, steam probes, which are miniature 14 'thermocouples, which are going to be suspended from the () 15 spacer grids. 16 MR. HOCHREITER: We've done it in FLECHT. Like in 17 this coiner here, we'll bring the thermocouple down. Now, I 18 tried thermocouples down and thermocouples up in the SEASET 19 program. These quench right away. These stay measuring 20 steam temperature until the froth region is a foot to two 21 feet below the grid. 22 DR. POWERS: When you try to measure steam 23 temperature like this with a thermocouple, don't you have to 24 make fairly significant corrections for just conduction of 25 the -- ANN RILEY-&' ASSOCIATES, LTD. fO Court Reporters
'1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
~
l J f 370 f 1 No, not if their small thermocouples. You have so )
~h 2 many L over D's for the thermocouple.
\ [& 3 And the correction
.you have to apply, though, is radiation, so you have to be 4 able to estimate the rod temperatures around it. But again, 5 that was pretty small. I mean, you're measuring 6 temperatures that can be as high as 1500 degrees, and it's a 7 25 degree correction. So these things work and they're 8 going to go in.
f 9 DR. SCHROCK: This is the 15 mil sheath and then, 10 what, a half mil wire inside it or -- 11 MR. HOCHREITER: Yes. 12 DR. SCHROCK: -- something like that? 13 MR. HOCHREITER: Something like that. Very 14 delicate. That's why we put it on this Inconel strip and () 15 braise it and then cut away as much of the strip as 16 possible. 17 This 14 mil Inconel strip, this is actually 18 thinner than the grid straps, about the same size or 19 thinner. I think it's thinner. I think the grid straps are 20 like about 15 or 15 mils. But by having three of them, it's 21 a very simple thing to quickly traverse.
- 22~ To measure drop size and drop velocity, we're 23 using a laser illuminated digital camera system where we've 24 got a laser which we diffuse, shine through the rod bundle.
25 They will observe then the drops, which we then collect and I ANN RILEY & ASSOCIATES, LTD. {is / Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 I
- )
i 371 1 measure with a camera. And there is software that has been ( ) ~ 2' developed and ee have worked with the manufacturer of this 3 instrument to use screening devices to separate out the data 4 and we had one student basically do a master's thesis on 5 figuring out how to calibrate this thing correctly. We 6 would set up bench tyce experiments on a milling machine, we 7 built a -- we had a three-by-three bundle that was heated; 8 we built a three-by-seven bundle, so it was seven rods deep; 9 and we.would drop drops down the subchannels and then we 10 would measure the drops that we could see with the laser. 11 So we've developed a calibration technique for this thing. 12 CHAIRMAN WALLIS: You must have both out of focus 13 because they're out of focus drops no matter what, aren't 14 they? () 15 MR. HOCHREITER: They are, but there's a rejection 16 criteria that throws them away.
.17 CHAIRMAN WALLIS: .But your image has a whole lot 18 of out of focus drops and a few good ones and it throws away 19 the others. It really becomes --
20 Except when they're in front of the other ones. 21 MR. HOCHREITER: Well, if they're in front of the 22 other ones, then, you know, you're throwing away both. 23 DR. KRESS: In dispersed droplet flow, you don't 24 have.too much of a problem. 25 MR. HOCHREITER: No. This works well in dispersed ANN RILEY & ASSOCIATES, LTD. s Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C., 20036 (202) 842-0034
372 1 droplet flow, but as the froth front approaches, then you're 2 going to overpower the system. [} 3 One of the problems also is if you're going to try 4 to -- and this is a problem we've got to basically deal with 5 -- if you're going to use the results, it's going to force 6 you to assume a homogeneous mixture of drops of the same 7 size distribution within the subchannel because you cannot 8 look around behind the rods; you're only looking thrcagh the 9 gaps. 10 CHAIRMAN WALLIS: Your laser is in line with the 11 camera? I would have thought that having it at 90 degrees 12 -- 13 MR. HOCHREITER: Well, it's diffused. 14 CHAIRMAN WALLIS: -- having at it 90 degrees would () ^ 15 16 be better. Then you don't illuminate the whole tube between the laser and the camera; you just illuminate the spot that 17 -- 18 MR. HOCHREITER: We looked at that and I don't 19 remember -- go ahead. 20 MR. FREPOLI: What this is doing is actually you 21 project a shade of the droplet. 22 MR. HOCHREITER: Right. 23 MR. FREPOLI: We investigated other systems where 24 you can play with angles, but they mostly use it for 25 combustion or spraying or very small droplets. l l ANN RILEY & ASSOCIATES, LTD. l f]if ( Court Reporters 1025 Connecticut Isvenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
s 1 373 1 MR. HOCHREITER: The thing that this system, and 2 probably those'as well, gives you is it allows you to get a
- 3. continuous record. One of the problems that we had in the 4 FLECHT/SEASET program is we would do these measurements 5 using high-speed cameras, but to get good photographs, you 6 had to film at speeds of between 2- and 4,000 frames a 7 second, so you could not -- you could not get a long-time 8 duration behavior because if you loaded more than several 9 !
hundred feet of film into the camcra, you basically would 10 destroy the film. That just would rip it to shreds. 11 So if you look in the FLECHT/SEASET report, there 12 is droplet information for two or three seconds, and the 13 tests were short enough that you really couldn't get a guy 14 to go up there and change a camera. 15 CHAIRMAN WALLIS: So this laser was flashing at 16 some high speed, is it? l 17 MR. HOCHREITER: Yes. ] 1 18 DR. POWERS: Once you get the distribution, you i 19 have a geometric size distribution, and what you want in the 20 codes is really an area-weighted distribution, isn't it? l 1 21 MR. HOCHREITER: I would think they would want 22 something like a Sauter-Mean. 23 DR. POWERS: A Sauter-Mean is a -- I mean, it's 24 just kind of a nonsense number. I mean, it. doesn't mean 25 anything, i O ANN RILEY & ASSOCIATES, LTD. D Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
374 1 MR. HOCHREITER: Well, I know I analyzed the
' l'2h 2 FLECHT/SEASET data where we had a distribution that was
- \ _,/
- 3. measured, okay, end then we could calculate from that 4 distribution Sauter-Mean. And we looked at things like the 1
5- change in the energy between two locations and the Senter-6 Mean did a very good job of representing that energy charga 7 compared.to the distribution. 8 DR. KRESS: It's real good if the droplets are 9 small enough that you don't have to worry about energy l 10 distributions inside the drop. I mean, if they're small 11 enough. 12 CHAIRMAN WALLIS: You can't flash the laser quick 13 enough that you get some stroboscope effect, you can follow 14 individual droplets and get that -- () 15 16 MR. HOCHREITER: CHAIRMAN WALLIS: Well, that's what you do. Oh, you do that. 17 , MR. HOCHREITER: This thing takes two pictures. 18 CHAIRMAN WALLIS: Oh, you get velocity as well as j 19 size? 20 MR. HOCHREITER: Yes. Yes. And in fact, the l 21 software in the program follows the drop for you because it I l 22 shows you -- on your second flash, it shows you where the 1 23' . drop was and where the drop moved to, and you know the 24 duration o' time, and then it measures for you automatically 25 the distanc( l' [ .. ANN RILEY & ASSOCIATES, LTD.
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l 375 1 CHAIRMAN WALLIS: Now, your original cartoon (7 2 showed things that didn't look much like drops. d 3 MR. HOCHREITER: Which original cartoon? 4 CHAIRM?.N WALLIS: Filaments and -- 5 DR. KRESS: It's way up. 6 CHAIRMAN WALLIS: Way up there is okay, but 7 eventually you get -- l 8 MR. HOCHREITER: That's right. This will start to 9 break down as you get closer and closer to the quench front. 10 DR. KRESS: It's equally important to get the 11 number of drops per unit volume as it is to get the 12 diameter. 13 MR. HOCHREITER: Right. Right, 14 DR. KRESS: Do you think you can get that out of r ( 15 this, too? 16 MR. HOCHREITER: Yeah, I think we'll have to make 17 some assumptiens because you don't see the whole subchannel; 18 you're seeing a slice through the subchannel, and there's 19 rejection criteria, okay? A drop that's hidden by the rod, 20 okay, you -- you have to reject. 21 CHAIRMAN WALLIS: You can't see it. 22 MR. HOCHREITER: Well, you can see a part of it, 23 j so you generally reject those drops. 1 j 24 DR. SCHROCK. Does stuff way up this high 25 contribute to the precursory cooling very much?
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a fe h 376 1 MR. h0CHREITER: That would be the flow regime { 2 that you would be in when you're turning around the 3 temperature. Your question --
.4 DR. SCHROCK: It's the heat transfer closer to the
- 5. quench front that's done the job, not the heat trausfer way 6 up there where it looks like this.
7 MR. HOCHREITER: Well, it's the heat transfer l 8 closer to the quench front that's giving you the liquid to 9 turn the temperature arornd, six feet above you. 10 DR. KRESS: It's -- the biggest effect is the 11 droplet suppressing the super-heated sink. l 12 MR. HOCHREITER: Right. 13 DR. KRESS: And that's way up high. !
'14 MR. HOCHREITER: That's right. l
() -15 Well, to measure the void fraction lower in the 16- ' bundle, we're looking at two options and we actually may I 17 take both. One is to use basically a gamma ray detector, i 18 ,
'okay? This stuff -- I believe they have the sources. Most
~19 of this equipment exists and it can be sent to Penn State.
20 We have to buy I think this piece here. And what we do , 21 would be to take and replace the quartz with Beryllium l l 22 windows, simply to increase the sensitivity of the gamma L - 23, ray. But this would be a straight gamma shot down one set 24 cn: more than one set of subchannels. 25 The other technique is this x-ray radioscopy, ! 4 l l
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i i 377 1 which I'm not as familiar with, but we have run a bench test () 2 3 on this that we showed to the NRC where basically you have X-rays that come in and they get a photo electric tube, 4' generate electrons, which then you can take and turn into an 5: image, and this can go to a digital camera. And we -- 6 CHAIRMAN WALLIS: Where are the drops in this? 7 MR. HOCHREITER: The drops -- this would be for-8 lower void fractions. 9 Now, we ran a bench test on a -- again, a three-10 by-three and then a three-by-seven where we shot along the 11 seven axis, okay? And we could align the camera so we could
'12 capture five gaps, and you could see the void fraction 13' difference by the difference in the light that was 14 generated, and so then you have to calibrate that system and O).
f y 15 then you can get a void distribution. 16 So the area where that is most useful is in here 17 and in here. 18 CHAIRMAN WALLIS: I don't understand why you have 19 to go from 2 to 3. You've already got it to light. Why do 20 you have to convert it to electrons and back to light again? 21 Why don't you just photograph or look at the -- 22 MR. HOCHREITER: I can't answer that. That's what 23 this other fellow says is the way to do it. i 24 The droplet laser will be looking at the flow l
-25 here. This system would be looking at the flow down here.
I J i ANN RILEY & ASSOCIATES, LTD. , '\ss O) Court Reporters , 1025 Connecticut Avenue, NW, Suite 1014 i Washington, D.C. 20036 I (202) 842-0034
378 1 And remember, we have a string of delta P cells along here, 2 so.we can make, I t". link, very accurate mass flow L 3 calculations to give us the total amount of entrainment 4 upwards, so we can get the total liquid flow that's leading 5' this region upwards in the bundle. 6 CHAIRMAN WALLIS: It's a beautiful facility. l l 7 MR. HOCHREITER: I've got my hat here'. 8 CHAIRMAN WALLIS: So the question is, why aren't 9 we doing.such fantastic experiments to answer every question 10- .in two-phase' flow? 1_1 MR. HOCHREITER: I think somebody has a bigger 12 hat. l
- 13 .DR. SCHROCK: Neither of those are spectroscopy, !
i 14 by the way.. l 15 MR. HOCHREITER: Okay He's the -- I'll tell him
'16 .that.
17 This is a barely legible figure. I do have a 18 -full-size drawing. I think the thing -- 19 MR. FREPOLI: Do you want-to go into this detail? 20 DR. POWERS: No, not really. 21 MR. FREPOLI: Yes. Let's -- 22 MR. HOCHREITER: The only thing I wanted to point 23 out is that we have tbemoccuples lined up downstream of the 24' grids. So the idea is to measure the effect of the grids. 25 Okay. The process in the program. We've ,O- ANN RILEY & ASSOCIATES, LTD. V Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034
379 l' completed task 1 through 10. We documented it in a peer 2 review report which has gone to the NRC. ( It has been peer 3 reviewed. We will be issuing it as a NUREG. We've 4 completed the design for the test facility. Most of the 5 equipment is either ordered or ready to be ordered. 6 We have developed a long-life heater rod with 7- Stern Laboratory. Again. the concern was cost and the fact 8 that we want to be able to rebuild this bundle with the same 9 rods. So we ran over 100 to 110 cycles testing these rods, 10 and they came out very well, nice and straight, no 1 11 thermocouple failures, and so forth. 12 We've developed an instrumentation plan which we 13 had peer reviewed. We've been performing a scaling 14 analysis. We've identified what distortions there are. We () 15 have a plan for addressing them. We've developed a COBRA-16 TRAC -- sorry -- COBRA-TF model to look at the scaling 17 effects and we'll be using this also to help determine test 18 conditions. 19 We have developed this laser-illuminated digital 20 camera system, we've tested it in a heated rod bundle 21 environment, and so we know it works, we know how to 22 calibrate it, and we've been taking and making available 23 whatsver data reduction and analysis programs we could get
'24 on FLECHT/SEASET basically to save time and effort.
25 So in conclusion, we've developed a detailed PIRT i i N ANN RILEY & ASSOCIATES, LTD. T, Court Reporters 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 (202) 842-0034 I.
r L 380 1
'l that identify the important phenomenon. We've compared 1
j 1
/~' 2 existing computer codes to that PIRT to identify modeling l N)'
l 3 needs in those codes. We've designed a test facility to 4 meet these modelling needs. We provided detailed 5 information to give us the data and data analysis of LOCA l 6 thermohydraulic conditions to address these needs, and we i 7 have designed the facility to cover a range of tests which I i 8 we believe will help provide the data to improve models to 9 improve the accuracy of the code. l l 10 CHAIRMAN WALLIS: Thanks. This will enable NRC to 11 make independent assessments of vendor claims that the 1 12 margin can be eaten away some more and it's still okay? 13 MR. ELTAWILA: We believe so, yes. 14 CHAIRMAN WALLIS: This is a large part of your 15 _ program? 16- MR. ELTAWILA: That's correct, yes. That's -- the 17 large experimental program that we have. 18 CHAIRMAN WALLIS: So if someone is looking for 19 something to cut, you would get more dollars out of cutting I 20 this one than -- l 21 MR. ELTAWILA: Actually, that's not a good idea ! 22 because we spend most of the money right now for ordering 1 ! 23 equipment and things like that. So -- 24 CHAIRMAN WALLIS: That sounds like it's a 25 ludicrous situation where just when you're ready to do l ANN RILEY & ASSOCIATES, LTD. Court Reporters 4' 1025 Connecticut Avenue, NW, Suite 1014 Washington, D.C. 20036 , (202)-842-0034 ] l a
381 1 everything --
- (\ 3 2 MR. ELTAWILA: And believe it or not, that G'
L 3 happened in the past several times. 4 DR. POWERS: It has happened. 5 MR.HELTAWILA: It has happened. 6 CHAIRMAN WALLIS: It's almost predictable. 7 MR. ELTAWILA: I actually had a program and spent 8 about $5 million on developing technology in the severe 9 -accident area, and by the time we reached the point where we 10 really can run the tests, they cut the budget. So we 11 developed the technology; we never run any tests after that. l- 12 I think that's most of the presentation that we 13 were planning to make, so as far as tomorrow, we'll play it 14 by ear. If you want to hear from me again --
) 15 CHAIRMAN WALLIS: I think it would be good.
l( I 16 mean, I think that if we can make it here tomorrow, we can 17 spend a little time because I think we didn't get into 18 everything. 19 MR. ELTAWILA: So you want Larry to come back so 20 we can have additional questions. 21 CHAIRMAN WALLIS: I think you should be available. 22 If we are here in the morning, if we're going to meet with 23 folks'for -- 24 MR. ELTAWILA: Okay. 25 CHAIRMAN WALLIS: -- a' morning session -- g ANN RILEY & ASSOCIATES, LTD. i s_/. Court Reporters 1025 Connecticut Avenue, NW, Suite 2 014 Washington. D.C. 20036 (202) 642-0034
I' ) 382 1 MR. ELTAWILA: We'll be available tomorrow. i
~
'[ ') _ 2 CHAIRMAN WALLIS: And I think we might have some 3 questions for him. 4 MR. ELTAWILA: Okay, i l 5 CHAIRMAN WALLIS: But you're going to organize us l 6' in the morning and make sure we don't go on a wild goose l l 7- trip? l 8 MR. ELTAWILA: I think, if I can pass a sheet of 9 paper with everybody's telephone number, I will be calling 10 you at your hotels. 11 CHAIRMAN WALLIS: We're all at the Hyatt, aren't ' 12 we? 13 MR. ELTAWILA: You're at the Hyatt? 14 CHAIRMAN WALLIS: Yes, r\
+
15 We can go off the record. The session is closed V} 16 now.
~
'17 [Whereupon, at 7:08 p.m., the meeting was 1 81 zecessed, to reconvene at 8:30 a.m., on Thursday, September
{ l 19 16, 1999.] ! l 20 21 l
-22 23 24 25
/~~h ANN RILEY & ASSOCIATES, LTD. l
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REPORTER'S CERTIFICATE This~is to certify that the attached proceedings
/ 'before the United States Nuclear Regulatory Commission in the. matter of:
NAME.OF PROCEEDING: MEETING: THERMAL-HYDRAULIC PHENOMENA-l CASE NUMBER: l 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 proceedings.
- 0
!fu)O i iW f. _
(! 6 Jon Hundley i Official Reporter Ann Riley & Associates, Ltd. LO
4 ADVISORY COMM!TTEE ON REACTOR SAFEGUARDS ()' '- THERMAL-HYDRAD lC PHENOlviENA SUBCOMMITTEE MEETING NRC RES THERMAL-HYDRAULIC RESEARCH PROGRAM SEPTEMBER 15-16,1999 ROCKVILLE, MARYLAND go o s g j 7 2 // TOPICAL AGENDA 1 TOPIC SPEAKER TIME wed . September 15,1999 l I. Introduction G. Wallis, Chairman 8:30 a.m. II. Resolution of GSI-23: 8:40 - 11:45 a.m. Reactor Coolant Pumo Seal Failure A. RES Presentation J. Jackson, RES e Proposed Resolution , Approach l BREAK (at Chairman's Discretion) B. NRR Presentation C. Jackson, NRR I e Regulatory Closecut of Issue C. Subcommittee Caucus 11:45 - 12:00 p.m.
- Follow-on Actions e Decision to Bring Item to ACRS for Review LUNCH 12:00 - 1:00 p.m.
Ill. NRC RES Presentation A. Introduction / Overview F. Eltawila, RES 1:00 - 2:00 p.m.
- 1. Overview of T/H Res-earch Activities / Future Work
- 2. Budget for FY00-05 (Five-Year Plan)
- 3. Response to ACRS Recommendations in NUREG-1635, Vol.1 (Sect. IV. H)
(] 4. Relationship of Research
T/H Ph:n. Sub. Mtg. Page 2 Sept.15-16,1990 (] Programs to Future Needs B. Thermal-Hydraulics / Reactor Physics Research BREAK (at Chairman's Discretion) e TRAC-P Maintenance / J. Uhle, RES 2:00 - 4:00 p.m. Consolidation e TRAC-BWR Maintenance J. Uhle o RELAP-5 Maintenance / J. Uhle IST Calculations e External Components J. Mahaffy, Penn. 4:00 - 5:00 p.m. and Maintenance State Univ. RECESS 5:00 p.m. September 16,1999 IV. Reconvene 8:30 a.m. B. Thermal-Hydraulics / Q Reactor Physics Research - Continued e OSU/ PUMA Facilities C. Boyd, RES 8:35 - 9:10 p.m.
- CFD Programs e Rod Bundle Heat Transfer L. Hochreiter, 9:10 - 10:15 a.m.
Penn. State Univ. BREAK 10:15 - 10:30 a.m.
- Boron Mixing Expmts/ J. Uhle 10:30 - 10:45 a.m.
Reactivity Transients e Basic Research C. Concluding Comments F. Eltawila 10:45 - 11:00 a.m IV. Subcommittee Caucus 11:00 - 11:15 a.m. A. Follow-on items from this Meeting B. Need for Additional Input for ACRS Repod on RES Safety Research Program
] C. Input to Safety Research Program Subcommittee V. Adjoum 11:15 a.m.
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Q SCOPE OF PRESENTATION STATION BLACKOUT Station Blackout (SBO) rule,10CFR 50.63, coping analysis considerations Estimates of core damage frequency (CDF) from SBO initiated RCP seal LOCA sequences (external events, internal flooding, and fires not included) Will show that the intent of the SBO rule, an industry average CDF from SBO of about 1E-5 per i year, is still met LOSS OF COMPONENT COOLING WATER (CCW) AND Q ESSENTIAL SERVICE WATER (ESW) Will give scoping estimates of CDF from CCW/ESW initiated loss of RCP seal LOCA sequences for a non-random sample of plants, biased toward plants where the risk was initially assumed to possibly be larger than average (external events not included) Indicate the nature of the plant specific l considerations which enter into the assessment of risk from these sequences
- Give the results of a survey of plants where because of plant specific considerations the risk is likely low, from these sequences o
1
b R P SEAL MODEL USED FOR LOSS OF RCP SEAL O COOLING-RHODES MODEL FOR WESTINGHOUSE PUMPS i We use a slight simplification of the model of Dave Rhodes. given in Appendix A to NUREG/CR-5167 l Two types of RCP seal failures on loss of cooling
- 1. RCP seals " pop open".
The seal opening forces on the movable seal ring of the second seal stage are increased, for a given seal face separation, as a result of two phase flow thru the seal faces, and the second stage seal faces separate. O The third stage face seais open with proaahiiity one, given popopen of the second stage seal faces. Popopen occurs at ten minutes after loss of RCP seal cooling, when the hot reactor coolant reaches the seal package. The probability of the popopen mode is 20%; epistemic uncertainty. If the seals of one pump pop open, the j seals of all pumps pop open. l l l 1 -)'. i O 3 l
1
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Bhodes Model for Westing. house Pumps, continued Q The leak rate from one RCP given popopen of the 2"d and 3'd stages is 182 gpm, for a pressure of 2250 psia and temperature of 550 deg. F.
)
- 2. Westinghouse O-Ring Failure Westinghouse "old" O-rings fail at two hours after loss of RCP seal cooling, with probability unity.
The associated leak rate is 300 gpm for P=2250 psia and T=550 deg. F. Westinghouse "new" O-rings do not fail during the mission time, unless the seals have popped open. The Rhodes model assumes that with the improved 0-rings there is a 50% chance of first stage O-ring failure, O given popopen of the second stage. i O 4
TIMES TO CORE UNCOVERY. Westinghouse Plants Q Assume, for station blackout, that the operator cools down plant according to procedures Then the core uncovers in about 5 hours if only the popopen mode occurs, without 0-ring failure (consistent with Rhodes model) if have O-ring failure at two hours, core uncovery occurs in about 4 hours, when the popopen mode of failure of the seals occurs at 10 minutes, and , between 4 and 5 hours if only the O-rings fail. l (consistent with Rhodes model, for old 0-rings). We simplify further, and assume that core uncovery ; occurs at 4 hours, whether only the popopen mode Q occurs, or the O-ring failure, or both. e L O 5 ~
b Rhodes Model for non-Westinghouse Pump _s O We assume no failures of polymer seals during the mission time. We assume a 20% chance of the popopen mode, just as for Westinghouse pumps
-- We assume a leak rate of 182 gpm per RCP, and core uncovery times as for a Westinghouse reactor.
These assumptions are for want of more information. In perticular, the leak rate of 182 gpm per RCP may prove to be conservative for non-Westinghouse pumps. For example, NUREG/CR-4821 (Rhodes, Hill, and Wensel) g predicts analytically that Bingham international 2"d and 3'd stages will popopen, but that the leak rate could range from less than.1 gpm to more than 100 gpm, with a nominal predicted leakage rate of 50 gpm. Also, the results of a SCE test on a Bingham international seal assembly, and comparison to analytical predictions, indicate some conservatism in the analytical predictions of instability thresholds. l C 6
IMPACT OF RCP SEAL LOCA ON STATION BLACKOUT O COPING ANALYSIS The station blackout rule,10CFR50.63, state that each plant must be able to cope with a station blackout of a specified duration. Plants are placed into two categories: 4 hour coping plants and 8 hour coping plants Given the validity of the Rhodes model, plants in the four hour category will still be able to cope with a 4 hour station blackout, even considering RCP seal LOCAs. O t i O 7
O seto. continued All plants in the 8 hour coping capability category have alternate AC sources. These alternate AC sources can maintain seal injection and CCW, but do not have ECCS puinps on their list of loads, and may not have the power to operate them. The alternate AC for Turkey Point Units 3 and 4 is available in 10 minutes after SBO. For al! other 8 hour coping plants, the alternate AC is available in one hour. Although the alternate AC could restore seal injection-and RCP thermal barrier cooling, current Westinghouse SBO emergency response guidelines state that RCP seal injection and RCP th'ermal barrier cooling should not be restored once the RCP seal package heats up. O -- The popopen mode will not occur for Turkey Point Units 3 and 4,'given the alternate AC works and comes online in 10 minutes. Therefore, SBO-induced RCP seal LOCAs do not affect the SBO coping analysis for the
. Turkey Point units. 'l For the other 8 hour coping plants, where'it takes one hour to startup and align the alternate AC, the popopen mode occurs with 20% probability, leading to a leak of c 182 gpm per pump,in our model. For Westinghouse plants with old, unqualified O-rings, the O-rings fail at two hours, and, in our model, there is a conditional probability of unity of core uncovery, given a SBO exceeding 4 hours.
O 8 o ____o
ESTIMATES OF CORE DAMAGE FREQUENCY DUE TO RCP O SEAL LOCAS INDUCED BY STAT!ON BLACKOUT Four Hour Plants If the'SBO duration is less than 4 hours, core uncovery from a RCP seal LOCA will not occur in our model. Losses of offsite power greater than 4 hours are with high probability severe weather reisted, according to NUREG/CR-5496, " Evaluation of Loss of Offsite Power Events at Nuclear Power Plants: 1980-1996". Plant centered losses of offsite power lasting longer than 4 hours have low frequency. Also, grid-related losses of l offsite power do not contribute: NUREG/CR-5496 notes I that these events have become increasingly rare and 1 none have occurred in the 1990's.
-Q.
-- For severe weather related losses of offsite power, NUREG/CR-5496 uses an industry average value for the non-recovery probability, not a site specific value. The probability a severe weather related loss of offsite power event is not recovered in 4 hours is .85, according to the lognormal distribution in NUREG/CR-5496.
I A typical 4 hour coping time plant has a severe weather related loss of offsite power frequency of about 5E-3 per year
-- For a 4 hour plant without alternate AC and with two diesel generators we estimate a probability of failure of
.the onsite diesel generators as about 0.003, as follows:
-Q.
9
)
O SBO. 4 HOUR PLANTS. continued DG FTS or run for % hour (DGFTS): .025 a common mode factor: .03 Test & Maint. unavail (DGTM): .03 Fall Prob. of onsite AC: a(DGFTS) +(DGFTS)2 +2(DGTM)(DGFTS) = .003 Therefore, obtain 1.3E-5 per year for contribution of ' SBO induced RCP seal LOCA to core damage frequency for a typical 4 hour coping time plant with Westinghouse RCPs and old O rings. This is conservative, since a 4 hour plant may have core damage for a SBO lasting more than 4 hours even Q without a RCP seal LOCA, e.g., from battery depletion. (To obtain the total SBO CDF from all sequences, the main additiorial contributor would be early core damage l from loss of the auxiliary feedwater system.) For a plant with Westinghouse RCPs and new O rings, or for a plant with non-Westinghouse RCP seals, get 20% of this value, or about 3E-6 per year, for the contribution of SBO induced RCP seal LOCA to the
. CDF.
O 10
s-- i I l Q Q_ ORE DAMAGE FREQUENCY CONTRIBUTION FROM SBO-INDUCED-RCP SEAL LOCAS FOR PLANTS REQUIRED TO COPE WITH 8 HOUR SBOS ! There are just 7 PWRs that fall in this category. i Therefore, look at each one individually. l l For Millstone Units 2 and 3, we obtained 2E-5 per year. I For Robinson Unit 2, we obtained 1E-5 per year. l l For the other 8 hour coping time plants, values of 3E-6 l per year or less were obtained. O i
. i f
11
CDF FROM SBO-INDUCED RCP LOCA, FOR PLANTS WHICH Q MUST COPE WITH AN 8 HOUR SBO Plant AAC EAC P(EAC) F(sw- CDF time success losp) from criteria RCP seal LOCA, on SBO Turkey Pt 10 1 out of 2 .003 .0305 /yr 3E-6 /yr 3 and 4 minutes Indian Pt 1 hour 11 out of 3 4E-4 .005 /yr 4E-7 /yr Unit 2 j Indian Pt 1 hour 1 out of 3 4E-4 .005 /yr 4E-7 /yr l 1 Unit 3 Millstone 1 hour 1 out of 2 3E-3 .035 /yr 2E-5 /yr Unit 2 Millstone 1 hour 1 out of 2 3E-3 .035 /yr 2E-5 /yr Unit 3 Robinson 1 hour , 1 out of 2 3E-3 .005 /yr 1 E-5 /yr , Unit 2 ! 1 Key: l AAC= Alternate AC source F(sw-losp)= frequency of severe weather LOSP EAC= Emergency AC source CDF= core damage frequency P(EAC)= Probability EAC is failed SBO= station blackout LOSP= Loss of Offsite Power O 12 t
- )
i
SUMMARY
. Effect of RCP seal LOCA on SBO sequences Q Plants which are required to cope with a 4 hour SBO can still cope with a 4 hour SBO, even taking into account SBO-induced RCP seal LOCAs. For a four hour plant with Westinghouse RCPs and old 0-rings, the contribution to the SBO core damage frequency from RCP seal LOCAs is estimated at about 1 E-5 per year, not taking into account the fact that even without a RCP seal LOCA core damage can occur for a SBO exceeding 4 hours (e.g., from battery depletion at 6 hours). For non-Westinghouse pumps, or Westinghouse pumps with new O-rings, the corresponding contribution is 3E-6 per year. Q -- For the eight hour plants the contribution to the SBO
. core damage frequency from RCP seal LOCAs is estimated to be 2E-5 per year for two of the plants,1E-5 per year for one plant, and 3E-6 per year or less for four of the seven units .
-- The intent of the station blackout rule,10CFR50.63, of having an industry average core damage frequency ;
from SBO of about 1E-5 per year appears to be met, l even considering RCP seal LOCAs.on SBO. O 13
v - L . l ESTIMATES OF THE CONTRIBUTION TO THE CDF FROM Q' RCP SEAL LOCAS ON LOSS OF COMPONENT COOLING J l WATER (CCW) OR LOSS OF ESSENTIAL SERVICE WATER (ESW) RCP seal cooling is supplied by two redundant systems . In plants with Westinghouse RCPs, or in B&W plants. l One system uses CCW to the RCP thermal barrier. The i other system uses RCP seal injection supplied by the l charging pumps. 1 In most CE plants, the only rneans of RCP seal cooling is with CCW to the RCP thermal barrier. 1 O l e 1 O- l 14 i
l p -RCP Seal LOCA on loss of CCW/ESW. continued Classic sequences: l i
- 1. Plants with RCP sealinjection A. CCW is lost. The HPl and charging pumps are dependent on CCW for seal and pump motor bearing cooling. Therefore, there is consequential failure of the charging pumps, and both means of RCP seal cooling are lost. A RCP seal LOCA occurs, with some probability. The LOCA cannot be mitigated because the HPI depends on CCW, l and fails. i B. ESW is lost. The CCW heats up and cannot C perform its function of cooling the RCP seals, or cooling the charging pumps. The sequence proceeds as in A.-
- 2. Plants without RCP seal injection.
Here, the loss of CCW leads directly to loss of RCP seal cooling, and a RCP seal LOCA with some probability. The HPI depends on CCW and
.therefore the RCP seal LOCA cannot be mitigated.
l s 15
O RCP seal LOCA on loss of CCW/ESW. continued There are many variants of these sequences, depending on plant specific features A. For plants with seal injection
- 1. The charging pumps may not require cooling (Westinghouse 2 loop plants: Ginna, Kewaunee, Point Beach Units 1 and 2, Prairie Island Units 1 and 2.) Alternately, the plant may have a backup pump independent of CCW/ESW to suppy seal injection (South Texas, Catawba, McGuire, the Oconee units). Then RCP seal cooling is maintained on loss of ESW/CCW, and the RCP seal LOCA does not occur.
O 2. The charging pumps may be cooled by ESW. Then loss of CCW is not a concern, only loss of ESW. (For example, Beaver Valley Units 1 and 2, Braidwood Units 1 and 2, Byron Units 1 and 2)
- 3. There may be a backup cooling system for the charging pumps, from the fire water system or other system. (For example, Turkey Point Units 3 and 4, H.B. Robinson, Three Mile Island Unit 1, North Anna, Summer).
O l 16
i Q RCP seal LOCA on loss of CCW/ESW. continued B. For all plants
- 1. The plant may have the ability to mitigate a small break LOCA without HPl by cooling down and depressurizing using the steam generators and using low pressure injection systems. The LPI may operate without cooling in the injection mode, and provision may be made to refill the refueling water storage tank and continuing in injection instead of going to recirculation. (Shearon Harris).
- 2. The HPI may not need cooling in the injection mode, and, for a sufficiently small LOCA may Q even operate in the recirculation mode, provided cooling is not lost to the containment fan coolers.
- 3. The HPI may be cooled by ESW. Then a RCP seal LOCA caused by loss of CCW can be mitigated. Losses of ESW, however, may be important.
The importance of the sequences will also depend on the initiating event frequency for losses of CCW and losses of ESW, which depend on plant specific considerations. For Westinghouse RCPs, the use of the new O-rings decreases the likelihood of the RCP seal LOCA. .O 17 J-
l O BRIEF
SUMMARY
OF PRELIMINARY ESTIMATES OF CDF CONTRIBUTION FROM RCP SEAL LOCA INDUCED BY LOSS OF ESW/CCW Fourteen units (nine planto, some dual units) were selected for quantification of the cdf contribution from loss of ESW/CCW Initiating event frequencies were taken from the IPEs, and these were combined with the Rhodes model. When the Rhodes model was used, the preliminary estimates of the CDF contribution ranged from 1.4E-3 per year to below 1E-5 per year. For nine units the CD,- was below 1E-4 per year. O -- For comparison, for these plants, the IPEs obtained no CDF contributions greater than 7E-5 per year, from RCP seal LOCAs induced by loss of CCW/ESW. The differences in results arise solely from the RCP seal model used. This was not a' random sample of units, but rather an attempt was made to select plants with a high contribution to the CDF from RCP seal LOCAs induced by loss of CCW/ESW, when the Rhodes model was used.
-- In addition to the quantitative estimates, plants were looked at qualitatively to see if their design precluded a high contribution to the core damage frequency from RCP seal LOCAs induced by loss of ESW/CCW.
O Twenty-five units were identified where this was the l
' Case.
I 18
Summarv,_CDF contribution. RCP seal LOCA on loss of O CCW/ESW The results are preliminary. One of the largest uncertainties is in the application of the Rhodes model to non-Westinghouse pumps. l The remaining plants must be reviewed. i 1 i O O ! 19
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