ML20213F630
| ML20213F630 | |
| Person / Time | |
|---|---|
| Issue date: | 11/10/1986 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| References | |
| REF-10CFR9.7 NUDOCS 8611140357 | |
| Download: ML20213F630 (98) | |
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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the matter of:
COMMISSION MEETING Briefing on Thermal Hydraulic Research Program (Public Meeting)
Docket No.
Location:
Washington, D.C.
Date: Monday, November 10, 1986 Pages:
1 - 68 8611140357 861110 PDR 10CFR PT9.7 PDR ANN RILEY & ASSOCIATES l (
Court Reporters
'l 1625 I St., N.W.
Suite 921 Washington, D.C.
20006 (202) 293-3950 4
O I
D i SC LA I M ER 2
3 4
5 6
This is an unofficial transcript of a meeting of the 7
United States Nuclear Regulatory Commission held on s
11/10/86 In the Commission's office at 1717 H Street, 9
'N. lJ., tJa s h i ng t on,
D.C.
The meeting was open to public 10 attendance and observation.
This transcript has not been 11 reviewed, corrected, or edited, and it may contain f
(_
12 inaccuracies.
13 The transcript is intended solely for general 14 informational purposes.
As provided by 10 CFR 9.103, it is 15 not part of the formal or informal record of decision of the l
16 matters discussed.
Expressions of opinion in this transcript 17 do not necessarily reflect final determination or beliefs.
No I
18 pleading or other paper may be filed with the Commission in 19 any proceeding as the result of or addressed to any statement 20 or argument contained herein, except as the Commission may 21 authori=e.
22 2S 24 25 l
8 A
1 1
UNITED STATES OF AMERICA 2
NUCLEAR REGULATORY COMMISSION 3
4 BRIEFING ON THERMAL HYDRAULIC RESEARCH PROGRAM 5
6 PUBLIC MEETING 7
8 Nuclear Regulatory Commission 9
Room 1130 10 1717 "H"
- Street, N.W.
11 Washington, D.C.
12 13 Monday, November 10, 1986 14 15 The Commission met in open session, pursuant to 16 notice, at 2:00 o' clock p.m.,
LANDO W.
ZECH, Chairman of 17 the commission, presiding.
18 19 COMMISSIONERS PRESENT:
20 LANDO W.
ZECH, Chairman of the commission 21 FREDERICK M. BERNTHAL, Member of the Commission 22 KENNETH M.
CARR, Member of the Commission 23 24 25
_ =
8 a
2 1
STAFF AND PRESENTERS SEATED AT COMMISSION TABLE:
2 S.
Chilk 3
W.
Parler 4
V. Stello 5
E.
Beckjord 6
B. Morris 7
8 AUDIENCE SPEAKERS:
9 L. Shotkin 10 11 12
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13 14 15 16 17 18 19 j
20 21 4
t 22 23 24 25
B 3
3 1
PROCEEDINGS 2
CHAIRMAN ZECH:
Good afternoon, ladies and 3
gentlemen.
Commissioners Roberts and Asselstine will not be 4
with us this afternoon and express their regrets at other 5
plants today.
6 This afternoon we will be briefed by the Research 7
Office principally, I understand, by Mr. Bill Morris, the 8
director of the division of reactor systems safety on the 9
ongoing and future direction of the Nuclear Regulatory 10 Commission's thermal hydraulic research program.
11 Additionally, the director of research, Mr. Eric 12 Beckjord is here to provide his introductory comments with ths 13 executive director for operations, Mr. Stello.
14 Thermal hydraulics has been an essential and major 15 portion of the agency's research program since the 16 establishment of the NRC.
The early years of the program were 17 focused on evaluating emergency core cooling system 18 performance providing a verification for 10 CFR Part 50 19 including Appendix K.
20 More recently, the program has been focusing on 21 developing best estimate analysis codes providing information 22 on various safety issues including pressurized thermal shock 23 and performing small break loss of coolant accident analysis.
24 The NRC's program benefits from cooperation and 25 participation both internationally and domestically.
Products l
3 4
1 from this program are accepted and used on a world wide 2
basis.
This meeting is an information meeting and no 3
Commission vote is anticipated.
4 Are there any additional comments from my fellow 5
Commissioners?
6
[No response.]
7 CHAIRMAN ZECH:
If there are none, then I will turn 8
the meeting over to Mr. Stello.
Will you proceed, please?
9 MR. STELLO:
Thank you, Mr. Chairman.
I will just 10 briefly support everything that you have said.
The research 11 program both at the AEC and the NRC in its early years spent 12 very, very large sums of money to develop the thermal 13 hydraulic understanding of what is now our commercial reactor 14 program.
15 The work is, in fact, very, very important and while 16 you would think we have all the answers to the questions that 17 can be asked, we certainly don't but you will be hearing about 18 the program that we have in place to increase our 19 understanding.
20 Mr. Beckjord, the director of the office of research 21 has some preliminary comments and we have a rather long 22 briefing today.
I notice we didn't get any water, so we will 23 try to talk fast and get through it.
24 CHAIRMAN ZECH:
We are just now going to get some 25 water.
8 5
1 COMMISSIONER BERNTHAL:
I was going to offer to lend 2
you some of mine, but I don't have any either.
3 CHAIRMAN ZECH:
We will take care of that.
4 MR. STELLO:
All right, Eric, if you will.
5 MR. BECKJORD:
Thank you, Mr. Stello.
Mr. Chairman, 6
Commissioners Bernthal and Carr, I am glad to introduce the 7
presentation today on the thermal hydraulics research 8
program.
I am accompanied by Bill Morris who is acting 9
director of the division of reactor systems safety and 10 Lou Shotkin who is here who is branch chief of the thermal 11 hydraulics branch.
12 I would like to address three basic questions about 13 the program before I ask Bill Morris to make his 14 presentation.
15 First, what is the thermal hydraulics research 16 program, it is the search for knowledge of the behavior of 17 reactor coolant systems primarily in this stage of development 18 in the off normal modes of operation including anticipated 19 transients such as loss of feedwater with a second fault then 20 occurring or an accident such as a break in the reactor 21 coolant system and loss of coolant.
22 The search proceeds by developing analytical models, 23 checking them against experiment and then by refining the 24 model and extending the experiment until agreement is 25 adequate.
8 o
6 1
Thermal hydraulics is an empirical science because
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2 heat transfer at the microscopic level can be described only 3
by correlation of test data and because fluid flow 4
calculations for entire systems are very complex depending on 5
the configuration of the system and requiring many assumptions 6
to carry them out.
That means testing to verify the 7
assumptions.
8 This is particularly true in the case of two phase 9
mixtures of steam and water, in the case of large or multiple 10 flow channels and in the case of thermal energy storage as 11 there is in reactor fuel elements or pressure vessel steels.
12 The second question, what is the relevance of the 13 thermal hydraulics research program to the regulation of power 14 reactors?
15 It is necessary to predict the behavior of coolant 16 systems in the various modes of operation as long as there is l
17 fuel in the reactor core to make sure that the fuel is always 18 coolable and to make possible problem diagnosis so that 19 reactor operators can be effectively trained to regain control l
20 after the initiation of accidents or transients.
21 The third question, why should the NRC do this 22 research?
It is important that the NRC has both'the 23 professional staff and the experimental facilities available 24 to it to carry out the confirmatory research in this area and i
by professional staff, I am talking primarily of those of the 25 i
l
I 7
1 contractors who do the research for us.
2 The NRC needs these in order to develop the data 3
independent of data from industry alone to make the most 4
effective regulatory decisions.
I do not mean to suggest that 5
data from industry is not useful.
It is as is data from 6
international cooperative programs.
Independent is the key 7
word in this context.
l 8
Parenthetically, I would add that the results of 9
this thermal hydraulics research is contributing to the 10 advanced LWR concepts that are under development now and these
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11 have some very significant, we believe them to have some very 12 significant safety advantages.
13 In conclusion, in my view the thermal hydraulics
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14 research program is essential to our research mission.
I need 15 your support for this program and I want to convince you that 16 it is merited.
17 I will now ask Bill Morris to proceed with his l
18 presentation.
19 COMMISSIONER BERNTHAL:
You don't have to convince 20 us.
You have to convince Congress.
21 CHAIRMAN ZECH:
Well, you might start with us.
I 22 think it will be helpful though to hear what you have to say.
23 Mr. Morris, proceed.
24 (SLIDE.]
25 MR. MORRIS:
Good afternoon.
4
I 8
1 (SLIDE.]
2 MR. MORRIS:
There are essentially four objectives 3
to the presentation this afternoon and I want to identify for 4
you those thermal hydraulics research issues that we have 5
resolved in the past and those issues that are yet 6
outstanding.
7 CHAIRMAN ZECH:
Could'you move a little closer to 8
the microphone, please.
9 MR. MORRIS:
Certainly, and in addition, those 10 issues that are as yet outstanding.
11 CHAIRMAN ZECH:
Thank you.
12 MR. MORRIS:
I would like'to describe the approach 13 we use to resolve issues in thermal hydraulics research, that 14 is the use of computer codes which have been validated against 15 a body of experimental data supplemented by special 16 experimental programs to provide the data needed.
17 I would like to describe this approach in terms of 18 some specific programs that we have completed and which we 19 have underway.
I would like to, in addition, make sure that 20 you understand the significance of this research in terms of 21 the agency decision making that goes on.
22 They are decisions about continued operation of 23 reactors, decisions about how to resolve generic issues which 24 might impose new requirements on reactors.
We want to make 25 sure that those are based on sound technical information and
I 9
1 there are decisions on major rules such as the ECCS rule and 2
the pressurized thermal shock rulemaking process.
3 So it is key to understanding the impact of the 4
research that you understand how this work goes into the 5
decision making process in cases where you may have to be 6
making decisions, you will understand how we went about 7
getting the data that we present to you.
t 8
[ SLIDE.]
9 MR. MORRIS:
There are essentially several general 10 issues that we talk about in thermal hydraulics research.
One is the fact that.we have a continuation of complex operational 11 12 transients that occur.
13 It turns out that there can be failures of equipment 14 that can initiate transients.
These can be complicated by 15 operator errors and what we are concerned about is that 16 although in every case up to now except for the Three Mile 17 Island accident we have been able to recover from these 18 events.
19 There may be some combination, a likely combination, 20 in fact, of equipment malfunctions and operator errors which 21 would lead the plant into a state in which recovery would be 22 quite difficult and perhaps impossible.
This could lead to 23 severe fuel damage and essentially a severe accident.
24 This program of thermal hydraulics research is intended to be preventive instead of mitigative in its 25
t 10 1
nature.
That413, the intent here is to learn what is needed 2
to be done to mitigate, that is prevent, operational events 3
from progressing towards severe fuel damage.
4 In addition to the understanding of complex 5
transients, for.the postulated design basis events that>are 6
used to evaluate designs, there are a number'of complex 7
thermal hydraulic phenomena that have been identified and to 8
be.sure that recovery from those events is possible it is 9
necessary to quantify and understand better how those i
10 phenomena could complicate recovery activities.
11 So we will be talking about that as another type of 12 research that will be done.
('
13 In the first case I was taking about complex 14 transients such as loss of feedwater events and those events 15 that might be generated by failures in balance of plant 16 equipment.
In the latter case, the recovery from postulated 17 accidents, we are primarily talking about events such as the 18 loss of coolant accidents, large pipe breaks or small pipe 19 breaks.
I 20 Finally, there is another type of issue that is the 21 issue that is defined and formalized to the extent that it 22 becomes a generic safety issue such as the issue of 23 pressurized thermal shock, the ECCS rule requirements.
24-Again, the bottom line here is that we are talking 25 about prevention of severe accidents.
i
t 11 1
(SLIDE.]
2 MR. MORRIS:
The next two slides are a summary of 3
some of those issues for which the thermal hydraulics research 4
portion has now been completed and where we have completed the 5
complete resolution of the issue or are well on the way.
6 Maybe just taking an example or two from this list that we are 7
going to be going into in some more detail would be that of 8
the pressurized thermal shock.
9 I will be discussing that and how thermal hydraulics 10 research has supported the resolution of that in more detail 11 further on in the presentation.
But essentially on slides 12 three and four, this is the list of achievements to date.
13 (SLIDE.]
14 MR. MORRIS:
There is a considerable amount of work 15 yet to be done and that is summarized on slide five.
16 (SLIDE.]
17 MR. MORRIS:
These are the outstanding issues 18 requiring thermal hydraulic research support and for almost of 19 these, I will be talking in more detail about these later on 20 in the presentation so I won't go into them further now and 21 maybe you will want to refer to them later on.
22 Let me point out to you that I have taken the l
23 liberty to use a number of acronyms, abbreviations for long 24 winded descriptions of experimental programs or computer l
25 codes.
t 12 The last slide in your package is a list of what 1
2 these acronyms stand for and it may be useful to you to refer 3
to that some time during the presentation.
I will be going 4
into a number of those in more detail later on but if you are 5
like me and don't particularly like acronyms but are willing 6
to tolerate them, that will help you follow the presentation.
7 CHAIRMAN ZECH:
I don't like them but I am willing 8
to tolerate them if it is necessary.
9 MR. MORRIS:
If we didn't use them, this slide 10 package would have been much thicker and much more difficult 11 to read so I took the liberty.
12 CHAIRMAN ZECH:
But we do need to put it in plain 13 English as much as you can.
14 MR. MORRIS:
We would be doing that.
15 CHAIRMAN ZECH:
Thank you.
16 MR. MORRIS:
I will be telling you what these are.
17 CHAIRMAN ZECH:
Good.
Let me just interrupt for a 18 second, you see, one of the problems we have and this is my 19 personal opinion in research especially is that it has been i
20 experience that research people are generally very good 21 talking to research people but you have to be able to talk to 22 those that are not research people like Commissioners and like 23 congress in order to explain your program.
24 It really is important and frankly, acronyms 25 sometimes, I think, get in your way.
I am not talking about
13 just this nuclear program but other experiences I have had.
1 2
Research people in my experience are very knowledgeable, 3
usually bright and have studied their subject very well and 4
understand it very well, but communicating it is not their 5
greatest strength.
6 It really is important to be able to explain the 7
fundamentals of some of the programs and that is why acronyms 8
are not always that useful.
I appreciate the fact that we 9
have gotten into that habit but I think it is important to 10 make the extra effort even if it makes your presentation a 11 little bit longer to make sure that you put it in real plain 12 language.
13 Go ahead.
14 MR. MORRIS:
Yes, sir.
15
[ SLIDE.]
16 MR. MORRIS:
Let me spend some time talking about 17 the approach that we use in thermal hydraulics research and 18 the reasons we do this, i
19 It turns out that th2re is a wide diversity of plant 20 design and operation, diversity and complexity of the possible 21 accidents and transients that one needs to consider in testing 22 these designs and it would be impossible to perform enough 23 direct experimental work to determine how plant systems would 24 perform.
25 What we do instead is to develop computer codes that
i 14 1
are developed to model these transients for a variety of C
2 situations, initial conditions, assumptions about component 3
failures that might occur during the transient or operator 4
errors that might occur during the ongoing transient.
5 The difficulty we have in doing that, however, is 6
that what we invariably do is we build a small scale facility 7
and then attempt to extrapolate from a validated code, 8
validated to small scale facility data to the behavior of the 9
full scale system.
10 That scaling extrapolation is a difficult one to 11 justify in some cases because in some cases different 12 phenomena scale differently.
Heat transfer may scale 13 differently than pressure drops and so we have to be careful 14 to examine the basic assumptions of how the thermal hydraulics 15 research has been performed.
4 16 If you will just bear uith me for a moment and look 17 at the next slide, we will come to this one in a minute.
18 (SLIDE.]
19 MR. MORRIS:
You will get an impression of the i
20 variety of plant types that you can see just for different 21 types of PWR's.
Here we compare the Babcock and Wilcox design 22 with in this case two steam generators and in that case for 23 each of the cold-legs, there are two reactor coolant pumps.
24 If you compare that to the Westinghouse PWR, there is one 25 reactor coolant pump per cold-leg.
5 15 1
/*
If you could envision the variety of balance of 2
plant designs that interact with this reactor coolant system 3
through the heat transfer characteristics of the steam 4
generators, you can envision that we have to model a wide 5
variety of different kinds of events with a lot of different 6
assumptions.
7 For example, the steam generators are different for 8
the two types of designs here, the U-tube versus the 9
once-through steam generator and that has a significant 10 bearing on how upsets in the balance of plant are transferred 11 into an impact in the. reactor coolant system performance.
12
[ SLIDE.]
13 MR. MORRIS:
Again, just to remind you of the k
14 diversity the next slide shows a boiling water reactor design 15 with again a different set of conditions and assumptions that 16 must be used in modeling plant behavior.
17 (SLIDE.]
18 MR. MORRIS:
If you look at the next slide, you will 19 see that within the course of a single event, a large pipe 20 break during the re-flood phase, there are a number of 21 different types of heat transfer processes going on and the 22 flow regimes that have a bearing on these are shown in this 23 slide and it represents the fuel rods and you will see the 24 different types of regimes that have to be modeled.
25 All of these features have to be modeled by the
I 16 1
computer codes and this is only a sample of what we are trying 2
to accomplish.
3 Let me go back to that other slide, slide number six 4
now.
5
[ SLIDE.]
6 MR. MORRIS:
I would like to point out to you that 7
in the process of assuring ourselves that we are able to do this properly, we continually check the computer codes against 8
9 experimental data that is developed from the scaled down 10 facilities and as we accumulate more data, we continue to test 11 our assumptions in the models that have been built into the 12 computer codes.
13
(
In addition to that work that is done by our 14 consultants at the laboratories, we employ the peer review 15 process extensively in the development of thermal hydraulic 16 computer codes and the data bases.
The peer review process is 17 employed in designing the experiments, in developing the codes 18 and in assessing the codes.
19 COMMISSIONER CARR:
Where do you find the peers?
20 MR. MORRIS:
We have consultants at the 21 universities.
We have an international code assessment 22 project where we go overseas and get expert opinion from 23 people doing similar work in foreign countries and that 24 involves, for instance, cooperation with 12 separate countries 25 to get peer review and in addition, access to data from a
=-
t 17 1
number of other facilities, experimental facilities in other 2
countries other than those that we are going to be describing 3
here today.
4 So it is the universities, various national 5
laboratories and usually when we have a meeting that we would 6
call a peer review meeting, we will get the industry to come 7
in and expose our work to the critique of the industry.
That 8
is usually a pretty vigorous criticism but we must expose what 9
we are doing to that kind of vigorous challenge in order to 10 feel that we are doing the right thing.
11 COMMISSIONER BERNTHAL:
I have to comment because as 12 you know this is a subject I have been beating now for two 13 years at least.
I would hope and, in fact, let me turn it
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14 around, I will ask the question, are we doing anything on what 15 clearly, I think, judging from your slides and the nature of 16 your presentation is a fairly academic subject here and it 17 obviously has applications to reality but it is pretty heavy 18 duty research in every respect.
19 Are we taking any special initiatives now to see to 20 it that the research work of our contractors and the people at 21 the national labs and in the universities that are working in 22 these areas eventually gets published in accepted professional 23 journals so that people put their names on what they do and 24 are held to account for it?
Are we promoting that sort of 25 thing?
8 18 e
1 MR. MORRIS:
Yes, we are.
The office of research 2
has recently developed and is in the process of developing 3
what we call a quality assurance plant to assure that our 4
research work is of the highest quality and it involves peer 5
review and a lot of internal controls and checks and balances 6
that we are talking about.
7 It also involves the consideration that ultimately 8
the work of these people is going to be published in the 9
journals for a wide peer review.
10 COMMISSIONER BERNTHAL:
Good.
11 MR. MORRIS:
I think it should be understood, 12 however, that the timing of that kind of publication may not
[
be appropriate for what we need.
13 14 COMMISSIONER BERNTHAL:
I understand.
Sure.
15 MR. MORRIS:
We need quality as the product is being 16 developed in addition to that sort of a background imposition 17 on quality on the whole process.
We impose quality in the 18 planning of experiments, in the conducting of the experiments 19 and the transfer of the experimental work into the regulatory 20 process.
So it is throughout that we try to develop this.
21 COMMISSIONER BERNTHAL:
Well, on the latter I would
+
22 agree.
I would question whether we have the ability to impose 23 quality on planning and conduct of the research.
Generally, I 24 think those judgments are often best made out in the field and l
25 in the national labs and by the experts out doing the work.
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19 1
MR. MORRIS:
Let me point out that our staff has a
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2 number of well qualified experts in thermal hydraulics who 3
have published in journals themselves.
In addition to that, 4
we bring the university consultants in for that peer review 5
process.
6 COMMISSIONER BERNTHAL:
That was my next question.
7 MR. MORRIS:
And to interact with the lab people who 8
are doing much of the work.
9 COMMISSIONER BERNTHAL:
My next question was what 10 efforts are being made in addition to the kind of ultimate 11 peer review and I view journal publications with your name on 12 it as ultimate peer review but I realize there is a time
['
constant there that tends to run in a few years when you look 13 14 back and ask yourself, "Is this individual or is this group 15 really doing work that stands up with time?"
16 The only way you find that out is if they have to 17 publish professionally.
18 There is another element though that insures our 19 contact with the people actually doing research in the 20 laboratory and that is a system of rotating people from the 21 laboratories and the universities into the NRC as temporary 22 managers, assistants, whatever it might be, to oversee program 23 management for short periods of time, maybe a couple of years.
24 Do we have any program for doing that or are we 1
25 thinking about doing it so that we get this influx of fresh
I' a
20 1
blood and ideas?
2 MR. MORRIS:
We are thinking of doing that.
It 3
happens frequently any way that you will find people on the 4
staff who have worked at national laboratories.
I don't have 5
a total number of years spent at national laboratories for our 6
current staff but I know that many of them have worked and 7
have come to the agency from the national laboratories.
You 8
are talking about a rotational assignment.
9 COMMISSIONER BERNTHAL:
Come in and go home.
Yes.
10 MR. MORRIS:
We are looking at the possibility of 11 getting more of our staff people out into the field so that 12 they get closer to the work.
13 COMMISSIONER BERNTHAL:
That is another approach.
14 MR. MORRIS:
That is the other side of that coin.
15 We are looking at a number of initiatives that we are going to 16 try to develop in the future on how to achieve this better.
17 It is not in place but we are considering it.
18 COMMISSIONER BERNTHAL:
Good.
These are not new 19 ideas.
Obviously, DOE has done this for years and 20 successfully I might say and so has the NSF and so have other 21 agencies that support research.
I just wanted to inquire 22 whether we are making'some efforts in that direction.
23 MR. BECKJORD:
I met with the directors of our i
24 programs at the laboratories several weeks ago when they were 25 all here in town for the water reactor safety information i
8 21 1
meeting and we discussed both of these topics.
The way we 2
parted was that they have formed a small committee to consider 3
both d these issues and they are going to come back to us and 4
give us their suggestions.
5 The peer review one, I think, is no problem.
They 6
have some reservations about the rotation program of their 7
people in but we are going to discuss it further.
8 COMMISSIONER BERNTHAL:
Good.
9 COMMISSIONER CARR:
Did you tell me it was currently 10 professors checking on contractors, contractors checking on 11 contractors or us checking on contractors?
12 MR. MORRIS:
All of the above.
(
13 COMMISSIONER CARR:
All right.
14 MR. MORRIS:
One other point to make regarding slide 15 number six is that we have now established as of last February 16 a technical integration center for thermal hydraulics at the 17 Idaho National Engineering Laboratory and this provides us a 18 source of personnel with expertise in thermal hydraulics who l
19 not only work on ongoing projects that are high priority 20 projects such as helping us with the ECCS rule revision 21 proposal, helping us with the B&W reassessments and so forth, 22 but are available for let's call it emergency direction to 23 highly important issues that might come along that we cannot 24 anticipate.
25 An example would have been that if at the time of
. m.
--s-----
e i
22 1
Three Mile Island, we did have a cadre of expertise around the p
2 various laboratories and this would be our way of assuring 3
that this expertise will remain there and available to us in 4
case the agency needs this help.
5 But they are part of the team of resources that we 6
have available to help resolve thermal hydraulics issues.
7 COMMISSIONER CARR:
Do we only control a part of 8
their workload or do we control it all?
9 MR. MORRIS:
We control the part of it that we pay 10 for.
They have other work that they may be doing for DOE but 11 there is always a strict partitioning to avoid any conflict of 12 interest when that comes up if a DOE project involves
{'
13 something the agency may have to regulate.
14
[ SLIDE.]
15 MR. MORRIS:
Let me at least look at slide ten for 16 a moment just to give you an idea of the scaling issue.
i 17 You will see there a comparison of three different i
18 scales, the full scale reactor compared to the loss of fluid 19 test, that is LOFT, and to the Semiscale facility.
The 20 picture isn't too good but it is difficult to show scaling on 21 a single picture like this and really give you the effect of 22 What is going on.
23 But the tall thin nature of the Semiscale can be 24 distinguished from that of let's say the short, fat j
25 characteristics of the LOFT facility in that picture.
We will 1
. ~..
i 23 1
be coming back and talking about other facilities of different 1
2 scales that we have in operation and under consideration later 3
on in the presentation.
4 (SLIDE.]
5 MR. MORRIS:
The specific elements of thermal 6
hydraulic research are listed in a very abbreviated form on 7
the next slide.
As I said before, the ultimate tools are the 8
computer codes and again, let me say that RELAP stands for 4
9 Reactor Excursion and Leakage Analysis Program and that is a i
10 two fluid, that is steam and liquid, code modeling i
11 non-equilibrium effects involving both thermal and mechanical 12 non-equilibrium code solves coupled mass energy and momentum 13 conservation equations with the plant features model as the 14 boundary conditions.
15 RELAP is essentially a one-dimensional code useful l
16 for production runs and sensitivity studies.
The TRAC code, 17 TRAC stands for Transient Reactor Analysis Code, has a 18 three-dimensional model of the reactor vessel allowing a 19 better modeling of that aspect of thermal hydraulic behavior.
20 We have TRAC versions operable for PUR's and BWR's.
1 21 Finally, we have a code called RAMONA which models
)
22 the couple neutronics and thermal hydraulics that are 23 important for certain BWR transients and accidents.
24 The codes are validated to data that come from the 25 test facilities of various sorts.
You have already seen a
-m_
s 24 1
picture of Semiscale and LOFT.
I might point out to you that 2
Semiscale and LOFT are now shut down.
3 The Semiscale facility is in stand-by now but that 4
is a cost that we are continuing to bear at this time but it 5
is a cost that we have to evaluate carefully.
6 COMMISSIONER BERNTHAL:
What does that mean?
Is the 7
fact that they are shut down, good, bad or indifferent?
Is 8
that a great loss or what?
9 MR. MORRIS:
Let me bring it out to you.
If we l
10 essentially shut it down in a non stand-by mode, right now it 11 is in a stand-by mode, we could reactivate it; if we shut it l
12 down in a non stand-by mode, we could not activate it again if 13 we needed to.
i 14 As you look down in the next set of facilities, the 4
15 CEC stands for Continuing Experimental Capability and it is 16 our current thinking that what we should be doing as an agency is to develop an ongoing continued experimental capability at 17 18 the Idaho National Engineering Laboratory that would allow us 19 to use the staff that would operate the Continuing 20 Experimental Capability to maintain Semiscale at essentially a 1
21 very low additional cost so it could be reactivated at any 22 time that it might be necessary.
23 It is importent to be able to activate a system like 24 that in the following sense.
During the Three Mile Island 25 accident, within hours after that accident occurred Semiscale
.-----r
,,-----,,r----r----,r-.-
m--,y
~,w-m
25 1
was up and operating trying to develop insights about the 2
pressurizer performance.
You remember that it was not well 3
understood at the time how a pressurizer would perform under 4
those conditions, so it was possible by having that facility l
5 available to gain rapid insights about what was going on.
6 As time passes and you have to maintain those staff 7
people there at Semiscale to keep that facility in stand-by 8
mode, that becomes an expense that you have to evaluate.
How 9
much should we be spending to maintain that capability there?
10 We believe that there is a need for a Continuing 11 Experimental Capability at Idaho to do other work than what 12 Semiscale can do, that is, address issues that are related to j
13 the continuing transients that occur in B&W plant designs.
l 14 So the concept that we are thinking of is to have 15 essentially a generic experimental capability where the data j
16 acquisition system could function for either Semiscale or the 17 B&W model design including some steam generator modeling that 18 wa would do there and in addition, a common energy source.
19 So essentially we could use it as though they were 20 interchangeable building blocks with the data acquisition and 21 the energy source common to a variety of designs and at the s
l 22 same time because that staff would have to be there, we get 23 Semiscale thrown in essentially at a very low cost allowing 24 this nation to keep a continuing capability to perform i
j 25 experiments of this type.
26 1
COMMISSIONER BERNTHAL:
Who else has.an apparatus
.m 2
like that?
Where else can experiments like that be done?
3 MR. MORRIS:
I am not sure.
4 COMMISSIONER BERNTHAL:
Is it a unique facility or 5
not?
6 MR. MORRIS:
We don't have this facility by the 7
way.
This is a conceptual design at the time.
We are talking 8
about the Continuing Experimental Capability.
9 COMMISSIONER BERNTHAL:
Oh, I am sorry.
All right.
10 MR. MORRIS:
I may be confused about what your 11 question was.
We don't have that facility.
We think it 4
12 should be designed and built and the reason we think that is
(
13 because if you look at the 2D/3D facility, that is a large 14 facility and I am going to describe it more fully later and 15 the ROSA IV facility and those are foreign facilities.
16 We have access to those facilities through 17 cooperative programs but they are in other countries and they 18 are not available for us to turn on and off as we please.
We 19 have to negotiate the experimental programs in those 20 facilities and FIST is in pretty much of a mode where it is 21 headed towards shutdown unless it is activated by DOE or GEN.
22 We are talking to them about that.
23 But that would be strictly related to BWR type 24 geometries.
25 So in looking at the test facilities and the future i
I 4
v y---
,.---.._,.._.-,,.m
.m.m..
._,----.-g. -. - - _ - -..
--m--
e 27 1
for test facilities, I think there are some decisions that r-2 will have to be made by the agency in the future regarding the 3
continued funding for these capabilities.
4 We are facing a point where we would have to be 5
relying on foreign capabilities at some point in the future.
6 COMMISSIONER BERNTHAL:
Is the CEC, is that a 7
particular piece of new hardware then that you would be 8
talking about?
9 MR. MORRIS:
Yes.
I will be talking more about how 10 it would be used.
Right now, we have a specific plan in mind 11 for what it would be doing.
12 COMMISSIONER BERNTHAL:
What would it cost?
{
13 MR. MORRIS:
We are estimating, let's see, I think 14 it would come to about $20 million dollars for the set of 15 experiments involving B&W designs only.
16 Now in paying for that, we would have at the same 17 time built a generic data acquisition system and a generic 18 energy source and if we decided in the future, for instance, 19 if there was an advanced design, an advanced LWR design 20 developed, and we felt that we needed some independent data to 21 help us judge the adequacy of that design, you could use the 22 same basic generic data acquisition systen and energy source 23 in conjunction with the actual piping geometry and steam 24 generator and whatever that came with that design.
25 But the current concept for a Continuing t
4 e
28 1
Experimental Capability is to model a model of the p
2 once-through steam generator typical of the B&W design and a 3
one-tenths scale B&W geometry representation that would allow 4
us to understand better complex B&W operational transients.
5 COMMISSIONER BERNTHAL:
I guess maybe I shouldn't 6
direct this question at you, but even though I am not 7
enthusiastic about the whole user fee idea and I think it is 8
very difficult to rationale or justify it if for no other 9
reason because we aren't consistent throughout the government 10 in its application, I have to say that when you tell me that 11 you want the NRC to fund even if we have one-third of our 12 budget from user fees that we should fund the facility to
^-
13 model a B&W system, I have to wonder why within that 14 philosophy that seems to be gaining credence, why the NRC 15 should pay for that.
16 MR. MORRIS:
Could I make the point that I have sort 17 of gotten ahead of myself here in the sense that on another 18 slide I am going to show you that we have initiatives to get i
19 the industry and DOE including EPRI to pay a part of the bill 20 for this facility.
21 MR. STELLO:
I think the first question though is we 22 should address is there a need.
As long as the need is there, 23 then it ought to be done, then as far as we are concerned, I 24 don't care who pays for it.
i 25 COMMISSIONER BERNTHAL:
Of course, neither do I but i
-~,-r
.m
__.__,-...m_,
e 29 1
one tries to be equitable about these things.
2 MR. STELLO:
I think the important thing is 3
establishing need.
4 MR. MORRIS:
I will go into that in detail later on.
5 COMMISSIONER BERNTHAL:
At least from the standpoint 6
from the research area.
7 MR. MORRIS:
Before leaving this slide, let me point 8
out that the tie, the link that is between the test facilities 9
and the computer codes are the projects we have on code 10 assessment, at the bottom of the page, I mentioned before the 11 International Code Assessment Program which we do in 12 cooperation with 12 foreign countries and the Code
{^
13 Applicability Reports that are being developed by our 14 technical integration center at Idaho.
15 These code applicability reports are essentially a 16 way to develop a direct impact on the day-to-day evaluation by 17 the licensing staff of proposed modifications to designs, 18 changes in technical specifications, the kinds of things they 19 have to evaluate all the time.
20 These documents will indicate how the codes such as 21 RELAP and TRAC have applicability to a variety of transients i
i j
22 and they are a tool that we think will be important in the 23 day-to-day work of the agency.
24 But that gives the link between the data base and 25 the code.
e 30 1
CHAIRMAN ZECH:
It does point out the necessity for
(' ' '
2 standardization in the future when you look at that slide and 3
you see all the various permutations and combinations.
You 4
just point essentially to some of the more basic ones.
It 5
seems to me that it certainly shows how difficult as you 6
pointed out earlier it is even to provide test facilities and 7
codes for the great variety of custom built plants we have in 8
our country.
9 MR. MORRIS:
Yes.
10 CHAIRMAN ZECH:
Go ahead.
11 COMMISSIONER CARR:
I assume when you get data from 12 actual transients, you feed back in and check these codes and 13 models to see that they compare.
14 MR. MORRIS:
To the extent possible but remember 15 that the instrumentation at the operating reactors was not 16 installed and designed to provide feedback of the sort that 17 you mentioned.
18 The instrumentation is there to provide sensing 19 information for trips and actuation of safety features and we 20 can do it to an exterat.
It can be done.
21 COMMISSIONER CARR:
You do do it?
22 MR. MORRIS:
Oh, yes, but it is not sufficient to 23 really tell you what is going-on in detail and allow you to 24 check out one of these computer codes except in the most 25 superficial sense.
h
e 31 1
COMMISSIONER BERNTHAL:
Why don't we have a program
~
2 with the cooperation of a given utility obviously to 3
instrument a few plants of each type and I will grant you it 4
is a little bit like sticking seismic sensors out in 5
California, it may happen and then again, it may not.
Would 6
that be a useful thing to do?
7 MR. MORRIS:
That is part of the problem is that 8
they are not there.
But the other part of the problem is that 9
the kinds of events we are talking about in modeling are not 10 the kinds of events that are happening day by day in the 11 plants.
12 It would be useful to get that data and it would 13 give us certainly some correctly scaled information about the 14 transients that are say benign and rather common.
i 15 What we are really interested in in this program are 16 transients that are unique, complex transients involving 17 multiple failures and those happen only rarely.
So there 18 would be the chance that if we did instrument one of the 19 facilities, we could wait for years before we would get a 20 complicated transient that would give us that feedback that we 21 need.
22 I think it is a good idea but I am not sure.
It is 23 a gamble if you made the selection as to whether you would 24 ever get the feedback from it.
25 MR. STELLO:
I think before we would want to say it l
-. - - - _. _ ~ - -
32 1
is a good idea, we would need to look.
Normally adding more
,.m 2
instrumentation means more penetrations, more places which can 3
cause incidence and accidents themselves.
I want to approach 4
it very carefully.
5 COMMISSIONER BERNTHAL:
You wouldn't do it that 6
way.
You would seek diagnostics that are benign obviously.
7 MR. STELLO:
To the extent you can but when you are 8
looking at particular densities and particular parts of the 9
system and temperature gradients and pressure distributions, 10 normally will mean additional penetrations.
So I say before 11 you can say is that the right thing to do, you need to 12 approach it very carefully.
13 COMMISSIONER BERNTHAL:
Yes, I agree.
14 MR. STELLO:
I don't think we have done the kind of 15 work you need to do to find out if that really overall is a 16 good thing to do.
17 CHAIRMAN ZECH:
I know we are giving you a lot of 18 interruptions but I hope that we can move along.
We are about 19 a quarter of the way through and we have half way through the 20 briefing period.
I would like to finish at 3:30.
I have 21 another commitment.
22 MR. MORRIS:
I fully intend to.
23 CHAIRMAN ZECH:
Could you kind of move along and we 24 will try to ask only the more important questions if we can 25 perhaps discipline ourselves a little bit.
Go ahead.
.~..
l e
33 1
MR. MORRIS:
Let me say that I am hoping that the 2
slides to some extent will stand on their own.
3 CHAIRMAN ZECH:
I am not condemning you.
I am just 4
saying that your Commissioners are helping you to extend the l
5 thing and we are going to try to do ourselves a little favor, 6
too.
7 MR. MORRIS:
Let's move on.
8 COMMISSIONER BERNTHAL:
Let's hurry this up a little 9
bit!
10 (Laughter.]
11 MR. MORRIS:
Let's move on very rapidly.
I do think 12 it is important to give you some idea of how the thermal j;
13 hydraulic research has been important in resolving a very 14 tough issue that the agency is considering.
15 CHAIRMAN ZECH:
You can tell we are interested.
16 That is why we are asking so many questions, but go ahead.
17 MR. MORRIS:
That is the pressurized thermal shock 18 issue.
19
[ SLIDE.]
20 MR. MORRIS:
I think if you will recall when 21 Mr. Arlotto was down here briefing you en the engineering 22 program, he pointed out the significance of his programs on 23 pressure vessel embrittlement in helping decide what the right i
24 PTS rule would be and how to set requirements.
25 There were other disciplines that had a significant
.-.--..-,-.---...-..---,.,-n-
,,_.-,,,,.,-,-,,,,,,---v--
e o
34 1
contribution to that.
Probabilistic risk assessment methods 2
enables us to understand what sequences we should be looking 3
at.
In other words, put a probability number on the sequences 4
that needed to be considered that could lead to pressurized 5
thermal shock and the computer codes, RELAP and TRAC, were 6
used to evaluate numerous transients of that sort to give us 7
an idea of how rapidly the cool down events would occur.
8 However, those transient codes are only able to give 9
us integrated loop flows and give gross information when you 10 really need to know the cool down rates in the vicinity of 11 those key welds in the pressure vessel.
12 This information coming from the computer codes was 13 supplemented by some special experimental programs that 14 measured the mixing of the cold injected ECCS water with the 15 water in the loops.
16 (SLIDE.)
17 MR. MORRIS:
Let's just run through very quickly the l
18 sequence of events and I am not going to spend much time on
.19 these except to say that the blue, what we have here is cold 20 EECS water injected into -- I guess this is a pipe, at a point l
i 21 where the arrow shows, cold water injected into a runner water 22 reactor coolant pump and you see the mixing that occurs 23 throughout that pipe.
4 24 The ordinary temperature would be about 180 degrees lf\\
25 and the injection temperature is at 60 degrees and within a
,,_.~m-_-__
,, ~ _ - _.. _ _. -,.,. _ _ _ _ _. _. _
35 1
length of a few meters, you get pretty good mixing so that you 2
don't have cold water coming into the vessel.
3 Go on to the next slide, please.
4
[ SLIDE.]
5 MR. MORRIS:
This just shows the same picture at a 6
later time, later time in the progress of the event.
7
[ SLIDE.]
8 MR. MORRIS:
Now we will look at how the mixing 9
occurs if you envision an annulus.
This is a slide that shows 10 how the annular region between the vessel and the shroud will 11 look if you folded it out and the injection would come in at i
12 the blue point up here, that is the cold water coming in to a 13 pipe and it mixes, for instance, the water would run down and 14 mix with the warmer water.
15
[ SLIDE.]
16 MR. MORRIS:
If you look at the next time frame, we 17 will see these temperatures are changing again.
i 18 Go on to the next slide, please.
19
[ SLIDE.]
20 MR. MORRIS:
This one shows finally a much later 21 time and the result of the cold water moving down but now it 22 has been warmed up to around 110 degrees, ahereas it was being 23 injected at around 50 degrees.
24 This is just an example of a way that this research
\\
25 program has been important in helping resolving an issue.
4 i
.n,
-,n. - - - - -... - - - -, - - - -.,
36 1
We found out what the cool down rates were in the 2
vicinity of the key welds and this enabled us to understand 3
how to make a decision that was crucial to the agency.
4
[ SLIDE.]
5 MR. MORRIS:
Let's move on and go back again to this
]
6 issue.
I got ahead of myself in talking about the B&W issue 7
but there are a number of transients as you are aware, I 8
believe, from last week's presentation on the B&W reassessment 9
that continue to occur in B&W designed plants.
10 There are unique features to these designs that make 11 us wonder about the capability to recover from those events.
12 Here in the thermal hydraulics research program, we would be 4
13 supplementing the B&W reassessment that is being conducted by 14 industry and we are more interested in the total system i
15 respense -- I am sorry, industry and NRR.
16 We are more interested in how this system, this B&W 17 system, would respond to complex transients initiated through 18 the balance of plant.
The fact that we have not got a good l
19 data base against which to verify and validate our codes makes 20 us want to learn more about whether these codes are adequate 21 to model these events.
'?
22 Remember the primary goal of the codes when they i
23 were originally developed was to analyze loss of coolant l
24 accidents, particularly large break loss of coolant 25 accidents.
They were subsequently modified and upgraded to i
-. -,,, - - -, - -.. - -..,.. -.. - -. -. -. - -., - -,.,,, _.. _. - - ~ -. -..
.. - -.. ~,. ~. - -,
37 1
help analyze small break loss of coolant transients but have 2
not been directed towards these complicated transients that 3
emanate from balance of plant and transfer into this reactor 4
coolant system through the steam generator.
5 Remember, that is a special design for a steam 6
generator and we don't have a data base for that.
7 So this brings us to the need that Mr. Stello was 8
talking about.
Do we have a need for an additional data base 9
to model B&W plants?
We believe the data base will come from 10 two areas.
One is a set of tests conducted at the continuing 4
11 Experimental Capability to get data on the heat transfer 12 characteristics of the once-through steam generator for B&W 13 plants.
14 We have such a data base that we have obtained 15 through a program in cooperation with industry for the CE and 16 Westinghouse steam generator designs and we need that for B&W.
17 In addition, although we have an experimental 18 program that was conducted at the Multiloop Integral System i
19 Test facility, the MIST facility, we have not cbtained from 20 that the kind of data we need to model events such as station 21 blackout, steam generator tube rupture, feedwater transients 22 and so forth.
23 The MIST facility which we show a picture on a 24 couple of pages downstream here is what we call a tall, thin 25 facility.
e s
38 i
1 (SLIDE.]
2 MR. MORRIS:
It models pressure drops and heights 3
very well and small break LOCA phenomena well but it would i
t 4
not model the kinds of transients we anticipate,need to be 5
evaluated.
This establishes what we believe'is a significant 6
need.
7 MR. STELLO:
They had the facility up there.
8 MR. MORRIS:
Oh, I am sorry.
There is the i
9 facility.
We also have and let's just pass this around, Lou, 10 it is about the only one that we have.
11 (Document distributed to commissioners.)
12 MR. MORRIS:
That picture is in color.
13 MR. STELLO:
That will help you better understand 14 what is there by looking at this.
i 15 MR. MORRIS:
That is the internal piping loops that 16 are inside that building.
This program was conducted in 1
i 17 cooperation with EPRI, with the B&W Owners Group but it was 18 directed towards understanding small break loss of coolant l
19 accidents and a set of issues that emanated from the Three 20 Milo Island accident.
j 21 What we have done now is the staff has developed a 22 plan, an integrated plan, that would make'use of MIST, the j
23 once-through steam generator facility that we proposed as,part f
24 of the Continuing Experimental Capability and a one-tenth I
j linear reduction in scale facility that would be built there 25 r
2
~-
a
-~
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-,-m,-,
e,
e f
39 1
in addition.
f 2
We intend to publish a NUREG document that would 3
spell out what data we are going to get from each of these 4
facilities in the future, where we would get the data for 5
various kinds of transients and events.
6 We would have already written, Mr. Stallo has written to the B&W Owners Group, and we have had meetings with 7
8 DOE and with EPRI to start the ball rolling on getting 9.
cooperative funding for those programs and we intend to be i
10 pursuing this in the future.
11 Let me point out one other thing that we are doing 12 in support of the B&W reassessment and that is, at Idaho we P
13 are asking Idaho to look at the functional analysis of what 14 the operator must do during a complex transient at a B&W plant 1
15 to see how much time he has to react to various swings in the 16 transient event.
17 (SLIDE.]
' 18 MR. MORRIS:
The functional analysis will integrate 1
19 essentially data coming from probabilistic risk assessment 20 programs on the rate of failure of components.
It will assess 21 human reliability data and responding to rapid transients and t \\
22 how well the operator can function during these events.
23 So we wanted to come up with an integrated 24 assessment of a variety of transients and in addition to that, 25 we will take into account the uncertainties in thermal
40 1
hydraulic behavior that nov exist related to say the lack of 2
data to modal the heat transfer characteristics of the 3
once-through steam generator.
4 We will be looking at all of that in a program 5
conducted at Idaho during the next year in support of NRR.
6 COMMISSIONER BERNTHAL:
How well informed has the 7
industry study group been of what our efforts are in this 1
8 area?
Have the communications between this new industry study 9
group and our own research people been good?
Is there an 10 exchange of information there so that they are tuned in to 11 what you guys think are important and what issues you think 12 are important and I guess, vice-versa?
13 MR. MORRIS:
NRR is the lead for this activity in i
14 the agency and we have worked closely with NRR to establish 15 what our program would look like.
This would be in support of 16 them but in doing that, I think that we have done it in the 17 context of understanding and our staff attends the meetings 18 with NRR and the industry to find out what industry is doing 19 and the direction they are taking.
I 20 In addition to that, there have been meetings 21 between our staff and the B&W Owners Group at the technical level to have interchange of ideas about what should be the 22 l
23 basis for an assessment.
I think there has been a healthy 24 amount of exchange.
25 Right now as I understand it, the focus of the
41 reassessment la to look at some fixes that could be taken 1
2 relatively soon, modifications to the integrated control 3
system, reduction in trip frequency, those kinds of things 4
that could be done by modifying the circuitry.
5 Our program is looking more at the system response 6
and I would say that we still have some more communication to 7
do with the Owners Group to begin to get them to look at this 8
the way we are doing but that is the agenda we have before us.
9 If we are going to expect them to help pay part of 10 the bill, they are going to have to understand what our 11 objectives are.
That was the pttrpose of our NUREG that lays 12 out the various data sources that we have that we can go to
/
13 and we will be working with industry to see if we can come to A
14 a common understanding of what the agenda should be for the 15 future.
16 COMMISSIONER BERNTHAL:
Have the considerations and 17 the studies that we have carried out on the unresolved issue 18 related to these plants, I don't remember what the number is, 19 have those considerations and the various data and information 20 that have been gathered in that study of ours been made 21 available to the Owners Group in every case?
Are they 22 thoroughly informed of what we have done and what data we 23 have?
24 MR. MORRIS:
I am not connecting on the particular 25 unresolved safety issue.
42
{
1 COMMISSIONER BERNTHAL:
That is USI-47 or something.
2 MR. STELLO:
That is the one that led to the MIST 3
program and the answer is we are hand-in-hand on that one.
4 That is how the MIST program came into being as a result of 5
that issus that started after the TMI accident that led to 6
that issue.
7 COMMISSIONER BERNTHAL:
Didn't we do a study of 8
Oconee or something as well?
9 MR. MORRIS:
Vic, he is talking about the A-47 10 studies?
11 COMMISSIONER BERNTHAL:
That's right.
12 MR. MORRIS:
The impact of control system failures 13 on safety.
k 14 COMMISSIONER BERNTHAL:
That is exactly right.
15 MR. MORRIS:
That is the one he mentioned and yes, 16 industry is well informed of what we have done.
We have 17 circulated the NUREG documents that were published by Oak 18 Ridge in this case for Oconee and Oak Ridge for Calvert Cliffs 19 but Oconee is the plant that you are talking about.
20 Oconee has commented on that NUREG and we worked 21 with them closely to see that we have done an accurate 22 modeling of the plant in ter as of not what our conclusions are 23 necessarily but in terms of our representation of the plant.
24 COMMISSIONER BERNTHAL:
All right.
\\
25 MR. MORRIS:
I am going to touch rather lightly on l -
43 1
some of the other phenomena that have been considered in our
(
2 programs but let me just do it in terms of a couple of 3
projects we have underway.
4 (SLIDE.]
5 MR. MORRIS:
If you look at slide 18, you will get a 6
quick summary of what the so-called 2D/3D program is about.
7 In this case the acronym is descriptive.
It is a program to 8
describe two dimensional and three dimensional phenomena that 9
are significant.
10 This program is in cooperation with Japan, Germany 11 and the U.S.
and the relative scopes of these various members 12 of the consortium are indicated here.
Let me just point out 13 that we achieve a good leverage from a program such as this.
14 It is expensive to us but there are complex three dimensional 15 issues that have to be addressed, issues such as upper plenum 16 injection, ECC, by-pass and what we have are several 17 facilities located in Japan and Germany.
18 Let's just show a few pictures of those now.
19
[ SLIDE.]
20 MR. MORRIS:
We would take a look first at a 21 cylindrical core test facility on slide 19.
This is 22 essentially a piping diagram but let's look at the building 23 and an.inside view of that rather quickly.
24 (SLIDE.]
\\
25 MR. MORRIS:
This again is located in Japan and the er-
-i--i-y i
ery-
a 44 1
facility is used to study steam binding and upper plenum 2
injection phenomena.
I will go into what those are in a 3
minute.
4
[ SLIDE.]
5 MR. MORRIS:
Here you get an idea of what the 6
facility looks like inside that building and you can relate to 7
the picture in your handout, the pipes that you see about 8
three-quarters up in the picture are the hot leg pipes that 9
you see in these diagrams here.
10
[ SLIDE.]
11 MR. MORRIS:
Let's go on and show it again.
- First, 12 the view in your handouts of the upper plenum test facility, 13 the UPTF.
This facility is being used to study ECC by-pass 14 and upper plenum injections and was used, in fact, remember 15 the data that I showed you on the mixing of cold water related 16 to PTS, that was the source of data for that.
17
[ SLIDE.]
18 MR. MORRIS:
Let's look at the building under 19 construction.
When this was under construction, this is what 20 the site looked like.
You will see the various pieces of the 21 facility, the broken cold leg simulator, the large storage 22 tank here, the steam receiving tank is essentially a 23 simulation of a containment and the blowdown would be in 24 containment so that simulates containment in this facility.
25
[ SLIDE.]
e 45 1
MR. MORRIS:
Just for a minute let's look at slide 2
22.
This is an illustration of the kind of phenomena that we 3
are studying in these programs in cooperation under the 2D/3D 4
program.
5 The issue here is the possibility of injecting 6
emergency core coolant water through the upper plenum.
That 7
is different from what normally has been done, that is, 8
injecting into the cold-leg and when you do that, the concern 9
has been that steam generated in the core region will rise and 10 inhibit the downflow of that upper plenum injection water.
11 There was no way of calculating this.
You will 12 recall that the TRAC can simulate certain three-dimensional 13 features but it wasn't capable of generating the kind of data 14 that is needed here.
15 What we found is that although the steam does to 16 some extent retard the downflow, there are regions where there 17 is some downflow and there are regions where steam is flowing 18 up.
In both cases, you get cooling.
The moving steam across 19 the core cools as does the coolant water moving down.
20 There was essentially a random pattern of regions 21 where you have steam flowing up or water flowing down but in 22 both cases some level of cooling was achieved and this data 23 base is going to allow us to go ahead and develop a better 24 understanding of how to model these phenomena in TRAC and 25 ultimately will help us finally wrap up the whole issue of
e 46 1
ECCS performance in another couple of years when this test f-2 program is completed.
3 COMMISSIONER BERNTHAL:
Why wouldn't you expect more 4
convective turbulance if you inject it at the top rather than 5
at the bottom?
6 MR. MORRIS:
I am sorry.
7 COMMISSIONER BERNTHAL: 'If you inject at the top, I 8
gather you are saying the steam flow up from the core impedes 9
the downward movement of the cooling fluid.
10 MR. MORRIS:
We expect it.
The problem is we don't 11 know how to quantify it.
That is the problem.
It has been 12 difficult to give credit for this kind of cooling because no 13 one knew whether or not that water would be held up completely s
14 or not.
15 COMMISSIONER BERNTHAL:
I see.
16 MR. MORRIS:
What we found is that it just isn't 17 being held up.
It is getting through and mixing and there is 18 some partial hold up but where there is hold up, the steam is 19 providing the coolant.
20 We could predict the phenomena and that was the 21 reason the test was designed this way but we couldn't quantify' 22 it before we did the test.
23 COMMISSIONER BERNTHAL:
I see.
24 MR. MORRIS:
Let's go on and take another example of 25 the phenomena that is being studied in the 2D/3D program.
i l
e 47 1
Let's go to slide 24.
/
2 (SLIDE.]
3 MR. MORRIS:
This is the steam binding phenomena.
4 This has been an issue for some years.
It turns out that 5
under certain conditions you can get steam generated in the 6
steam generator because the heat fluxes have been reversed now 7
and you can get a lot of steam generated up there and what 8
that does is that depresses or causes a back pressure that 9
results in slowing down the rate of re-flood as the ECCS flow 10 and this would be a case where you would have ECCS injected 11 into a cold-leg not upper plenum now.
12 The flow would be through the downcomer and upwards
(
13 through the core but with steam built up there, there is a 14 back pressure that inhibits the flow freely up to the core.
15 Now we have been able to measure the rates at which that flow 16 can take place under realistic conditions.
17 You see the 2D/3D program has achieved in particular 18 in the case.of the upper plenum test facility almost full 19 scale characteristics in terms of vessel modeling.
20 Let's go into one more phenomena, that of ECC 21 by-pass.
22
[ SLIDE.]
23 MR. MORRIS:
I would point out here that the artist 24 has his own idea of what the picture for condensation is.
It 25 looks as though it is a spiral but ignoring that for the time e
O
48
? -
being,.you see that if you envision this annular region 1
2 between the vessel and the core barrel, envision flow coming 3
in from the accumulator through the reactor coolant pipe into 4
the vessel and that flow is diverted in principle around that 5
cylindrical vessel and could go directly right on out the hole j
6 in the other side if that is the path of least resistance for 7
flow.
8 There was no way to determine to model these 9
pressure drops around the vessel in different directions to 10 find out whether there was a preference for flow down through 11 the annulus and up into the core or around and out the hole so 12 now we are evaluating this as full scale in the upper plenum 13 test facility.
14 So far, the preliminary data obtained at smaller 15 facilities tends to show that yes, there is ECC by-pass but it 16 does not prevent the core from being cooled.
We will now be 17 able to quantify the degree to which that is a factor and that 18 will be a useful data base to allow us to go on and finally 19 wrap up this whole issue of emergency core cooling system 20 performance.
21 That is a legacy for years and years that we have 22 been working on ever sir:e the original rule making and the i
23 concerns that were raised ten years ago about this phenomena 24 are now being wrapped up through our program.
25 (SLIDE.]
O 49 1
MR. MORRIS:
Let's go on to slide 28 for a moment.
f 2
Excuse me, back up, slide 27.
The ROSA-IV experimental 3
program is a program in cooperation with the Japanese.
Here 4
on the slide we indicate the scope of supply of the various 5
parties and the leverage that is obtained and indicate the 6
regulatory issues being addressed in the program.
7
[At this point in the proceedings, Commissioner 8
Bernthal exited the Commission meeting.]
9 MR. MORRIS:
Just to give you an idea of what this 10 facility looks like, I have given you a piping diagram in the 11 next slide, slide 28.
12
[ SLIDE.]
13 MR. MORRIS:
This is essentially a full height / full 14 pressure facility at 150th volume of a normal PWR.
15
[ SLIDE.]
16 MR. MORRIS:
If you look at the next slides that 17 show the building that this facility is located in and going 18 on, the facility itself inside the building.
19
[ SLIDE.]
20 MR. MORRIS:
This is the upper part.
If you can 21 refer to your notes on slide 28, you will see the legs coming 22 out at the top of the facility and that is what you are seeing 23 here.
24
[ SLIDE.]
25 MR. MORRIS:
Now go on to the next slide and there i
- - - - - - - - - - - ^ - - - - - - - - - ^ -
e 50 1
is another view of it to give you an impression of the size.
2 The signs by the way are telling the workers to please observe 3
the safety procedures.
Someone translated those for us.
4 Let's go on.
Look at slide number 30 now.
5
[ SLIDE.]
C MR. MORRIS:
This will indicate to you one of the 7
particular phenomena that we are studying in this facility and 8
that is that of liquid hold-up in steam generators.
9 It turns out that under certain conditions you can 10 develop steam voids in the steam generator U-tubes and they 11 can distribute it in such a way that you can have significant 12 quantities of liquid held up in the steam generators during a 13 small break LOCA accident.
4 14 This phenomena was first predicted in application of 15 codes.
It was verified to be real in a Semiscale test and now 16 finally in the ROSA-IV program, we are able to provide some 17 quantitative understanding of just how significant this is in 18 terms of inhibiting cooling during small break loss of coolant l
19 accidents.
20 Another example of a different kind of a pipe break 21 that is being addressed in :
ROSA-IV program is that of the 22 potential for instrument tube ruptures and you will see that 23 on slide 32.
24 (SLIDE.]
25 MR. MORRIS:
The concern here was that these m._ _ _..,.
,_.__.my
_-,_,_,,_m._
c_
O a
51 1
instrument tube lines wind through circuitous routings around 2
the plant and there are a number of locations where they could 3
be broken say in a seismic event.
You could get multiple tube 4
ruptures and that kind of event had not been analyzed before.
5 It turns out that the flow patters that develop are 6
different from anything that would be postulated from broken 7
pipes in the cold or hot legs and the ROSA-IV program is 8
establishing a data base to help us understand how to model 9
this kind of phenomena.
10
[ SLIDE.]
11 MR. MORRIS:
Finally just to indicate on slide 33, 12 there is at least in one instance an outstanding issue we are 13 trying to understand for BWR designs.
14 It turns out that in a lot of the data that came 15 from the cooperative program between industry and the agency 16 and the FIST program, has resolved a number of concerns about 17 BWR transient behavior.
18 In this case, however, we are looking at the 19 possibility that in recovery from an ATWS event, that is 20 anticipated transient without scram where control rods are not 21 injected into the core, that the possibility that the boron 22 that is injected could stratify in layers at the bottom of the 23 vessel and if that boron does not mix well into the system, it 24 doesn't provide the needed reactivity shutdown effect.
25 There are some measurements being conducted now to
52 1
quantify the degree to which stratification could occur.
2 (SLIDE.]
3 MR. MORRIS:
I said that I wanted to be sure and 4
let's look at slide 34 that you understood some of the 5
implications of the work that we are doing for decision 6
making.
7
[At this point in the proceedings, Commissioner 8
Bernthal re-entered the meeting.]
9 MR. MORRIS:
All the phenomena that I have just 10 been talking about, the steam binding, ECC by-pass, liquid 11 hold up in steam generators and small break LOCA events, i
12 different locations from what we have considered before for 13 injection of coolant, that is, the upper plenum injection and I
14 different locations for pipe breaks, that is the simultaneous 15 rupture of a number of instrument lines, all are providing 16 data that will allow us to finally we hope resolve one of the 17 outstanding issues for the last 23 or more years and that is,
)
{
18 the performance of the emergency core cooling systems.
19 When the original ECCS rule was written, we didn't 20 have these sophisticated three-dimensional non equilibrium 21 two-phase computer codes that we now have.
We didn't have 22 this body of experimental data that we used to validate those 23 computer codes and we couldn't quantify uncertainties in the 24 area of ECCS performance at that time.
25 Therefore, the agency was forced to impose rather i
e O
53 1
restrictive requirements in the form of a number of models
,~
2 that were imposed in Appendix K to 10 CFR Part 50.
Now we are 3
approaching the time when we believe, the staff believes at 4
any rate, that it will be possible to come to terms more 5
realistically with the way the ECCS systems would actually 6
perform and a proposal has been sent by Mr. Stello to the 7
Commission proposing a revision to the ECCS rule.
l 8
I would imagine that that in and of itself would 9
require another briefing specific to that revision.
I won't 10 go into it any further here, but it does point out and as 11 another example in addition to that if the PTS and the 12 resolution of a number of generic safety issues that I 13 mentioned earlier in the presentation how thermal hydraulics L.
14 research is going to be impacting the decision making process 15 in the agency.
16 I would just mention a couple of other factors.
I 17 include a couple of slides on our international code 18 assessment program.
I have already discussed with you the 4
19 fact that we have cooperative programs with 12 countries.
We 20 are in negotiations with three other organizations.
21
[ SLIDE.]
22 MR. MORRIS:
On slide 37 you will get an impression 23 and I won't go into descriptions, don't be alarmed, of what 24 all these facilities are but there are a number of facilities 25 around the world being operated in other countries, France,
o 54 1
Sweden, Germany, Italy, Finland and the United Kingdom which 2
countries are also participating in the international code 3
assessment program and through this program we are therefore 4
getting indirectly the benefits of all of these experimental 5
programs.
6 So I think there is a significant leverage achieved 7
in addition to the fact of what I think is a very useful peer 8
review of our codes.
9 Again I want to bring back to your attention the 10 ongoing work at the technical integration center in Idaho.
11 Let me point out that internally to the agency, there is a 12 committee that meets that is comprised of the various vendor j
oriented licensing divisions within NRR and the office of 13 14 research where we establish recommendations for the different 15 office directors for what the priorities within the agency are 16 for thermal hydraulics research.
17 We then once these priorities are defined and the 18 programs that we need are established, we turn much of this 19 over to the technical integration center at Idaho and they I
20 carry out some of the high priority work in support of such 21 issues as the ECCS rule revision, the design of the continuing 22 experimental capability at Idaho and the support to the B&W 23 design reacccasmcnt.
24 COMMISSIONER CARR:
What is a nuclear plant 25 analyzer?
What does it do?
o 55 1
MR. MORRIS:
What that is is a user friendly 2
computer terminal that allows the staff and the NRR, the 3
licensing staff and NRR who have to deal with these codes day i
l 4
by day, to rapidly set up and run the computer code.
1 5
[ SLIDE.]
6 MR. MORRIS:
Here, for instance, is a pictorial of 7
what the user might see on the screen.
That represents a B&W 8
two-loop plant on a generic basis.
If he wants to model some 9
particular plant such as Oconee or Davis-Besse, he has to put 10 in the particular dimensions and characteristics that are 11 appropriate to the plant he is modeling.
12 Then he can choose whether he wants to run RELAP or 13 TRAC and what version of that he wants to run and he can do 14 sensitivity studies.
He can interact through the computer 15 terminal and make different assumptions about the initiating 16 conditions and things that night go on even during the 17 transient.
18 So this is a tool that gives the licensing staff and 19 consultants, the people at the laboratories, ability to 20 rapidly use the tools that are developed in the program, the 21 computer codes.
22 I think that is about all we really have to cover 1
23 today.
24
[ SLIDE.]
25 MR. MORRIS:
The last slide, slide 39, essentially
~ _., _ _ _ _ _ _. _ _ _ _. _ _. _... _ _ _. - _ _. _ -.
o o
56 1
gives you an impression of how we have been making an effort 2
to develop cooperative funding with both the United States 3
industry and the foreign countries to help support the thermal 4
hydraulic research program and that continues to be one of our 5
goals.
6 We will be vigorously pursuing that kind of activity 7
in the future.
That is all I have to say.
8 CHAIRMAN ZECH:
All right.
Thank you very much.
9 Commissioner Bernthal.
10 COMMISSIONER BERNTHAL:
I just have one additional 11 question, I guess, on substance here and that is the question 12 about ATWS that was brought up or brought up again I should 13 say last summer and I think Vic, you sent a SECY paper down to s-14 the Commission that deals with these calculations carried out 15 by EPRI that shows within their realistic appraisal or that of 16 their contractor a foreigner psi greater pressure than we 17 thought or than Westinghouse thought and using more 18 conservative assumptions up to 1,000 psi greater pressure.
l 19 I don't know what the resolution of that issue was 20 with ACRS nor do I know what you folks have done with that but 21 I do see that you have touched on that issue here earlier in 22 the presentation.
23 Where do we stand on that?
Are you folks following 24 up on that?
What is going on?
25 MR. MORRIS:
Let me ask Lou Shotkin if he can inform
"7-
i 57 1
us of an update on that.
2 CHAIRMAN ZECH:
Good.
Would you identify yourself, 3
please, Lou?
4 MR. SHOTKIN:
Yes, Louis Shotkin.
I am the chief of 5
the reactor systems branch doing the thermal hydraulic 6
research work.
We are not doing anything specific on that 7
ATWS problem.
8 We are typically asked to do this kind of work by 9
NRR through this regulatory research review group that 10 Dr. Morris mentioned and they have not asked us to really look 11 at this yet and we haven't done anything.
12 MR. STELLO:
We will get you an answer.
13 COMMISSIONER BERNTHAL:
Who is looking at it, NRR?
14 MR. STELLO:
We will get you an answer.
15 COMMISSIONER BERNTHAL:
You can answer for me who is 16 looking at it.
Is NRR paying attention to this?
17 MR. SHOTKIN:
Yes.
NRR is taking the lead on this.
18 It is the Westinghouse group.
19 MR. MORRIS:
Remember that they have access to the 20 computer codes through the nuclear plant analyzer and they do 21 a number of independent assessments and sensitivity studies 22 through the use of those codes.
That is a tool that we 23 provide.
We don't necessarily get involved in their 24 day-to-day evaluations.
We are just a step away from that.
25 COMMISSIONER BERNTHAL:
You may be getting more i
_ _,. _. _. _ _ _. _ _ _ _ ~
e 58 1
involved soon as I understand it.
2 All right.
Let me just make a comment and then I 3
will let this thing rest for today because time is running on.
4 I would just urge and I know Eric has heard me say 5
this more than once already that we try very hard to package 6
this kind of program and presentation in a way that is 7
comprehensible to the Congress because it is one thing to come 8
before even the commission and discuss these issues where the 9
Commission is at least somewhat technically qualified.
10 It is quite another to go before the Congress.
I 11 did note that at one point you spoke of explaining how thermal 12 hydraulic research influences or impacts on decisions.
- Well, 13 to oversimplify, I would suggest that when you go to the Hill, 14 you start out with the decisions.
j 15 We need to make these decisions and then explain 16 what research you need to make those decisions.
I would go at 17 it the other way around, in fact.
Somehow we have to find a 18 formula for getting across these ideas better.
19 I think rather than starting with the technical in i
20 front and explaining how it relates then to decisions, we have 21 to begin starting out with the decisions that need to be made 22 and tell them how much money it is going to take and then if 23 they want to know, we can get into the technical details.
It 24 is just a tip.
25 I am not sure that is the answer but I thought I l
59 1
would toss that idea out.
Otherwise, I appreciate your coming 2
in today.
3 CHAIRMAN ZECH:
Thank you.
Commissioner Carr.
4 COMMISSIONER CARR:
Sure, I got one.
I still don't 5
understand without full scale data how you verify your 6
scaling factors.
7 MR. MORRIS:
We do have the UPTF data which is a 8
full scale facility.
It is just beyond the capability in 9
terms of resources to develop enough full scale test 10 facilities to allow us to prove without a shadow of a doubt 11 that we have scaled the phenomena correctly.
12 The way we go about it is we, for instance, just 13 recently had a session in which we invited university 14 representatives, the various laboratory consultants and the 15 industry in to talk about the issue of scaling as a special 16 topic and we continue to have various researchers try to look 17 at this issue but I don't have a simple answer that tells you i
18 how we can lock that one up.
19 It is a matter of a body of expert judgment that has 20 to go into the basis for when we have enough scaling data.
21 Let me point out that what we do essentially is we have 22 different facilities at different scales and we test the codes 23 at different scales to try to get a handle on what is 24 important in going from one scaling level to another.
25 That plus expert judgment is about as good as we are
o 60 1
going to be able to do unless we have many, many more 2
resources to allow a larger body of full scale testing.
3 Remember I told you that it would cost about $20 4
million dollars over the next two or three years to build a 5
one-tenth linear scale facility in Idaho.
That is one-tenth 6
scale.
7 I don't know what the cost would be for a full scale 8
facility.
I wouldn't even begin to go down that road.
I 9
think we have to rely on the expert judgment and the various 10 separate effects test programs and enough different scaling 11 test data to allow us to gain confidence that we have it.
12 COMMISSIONER CARR:
You have some full scale 13 facilities that aren't ever going to generate power, I think.
\\
14 COMMISSIONER BERNTHAL:
That's a thought.
15 MR. STELLO:
Are you suggesting that maybe someone 16 ought to buy one of those?
17
[ Laughter.]
18 COMMISSIONER CARR:
I just threw it out for a 19 comment.
You might get it cheap.
20 MR. STELLO:
I suspect even if you got it cheap, it 21 would exceed our budget significantly.
22 COMMISSIONER CARR:
My concern is that some things 23 are just impossible to scale and there is a lot of data out 24 there in those plants that you are probably not tapping that 25 is available.
o 61 1
MR. MORRIS:
Just envisioning using one of those 2
plants that is not being operated --
3 COMMISSIONER CARR:
No, I mean in a standard 4
operating plant, there is a lot of data and there are a lot of 5
data points that you aren't getting.
6 MR. MORRIS:
That's true and I think we should look 7
further into that.
We do normalize our codes to operating 8
data but we don't have an organized program to go out and 9
extract that information for the reason that I mentioned 10 before.
11 The instrumentation that we would need is not there 12 and the plants do not operate even during transient conditions 13 normally under the kinds of conditions that we are interested 14 in.
We are interested in pretty extreme transients.
15 COMMISSIONER CARR:
I understand that but I am just 16 saying that you shouldn't ignore what data is available.
17 MR. MORRIS:
We don't.
We use the data available.
18 It just doesn't do what you want, I think, is what I am 19 saying.
20 MR. STELLO:
I really think if you really want to 21 get a full briefing on scaling, it is a very complicated 22 subject and there are a lot of facilities that are full scale 23 that you do have tests on of certain typas like over in l
24 Sweden, for example.
They have a reactor over there which had 25 a containment and an awful lot of pressure suppression testing
o 62 1
and containment testing, the vendors have done quite a bit of 2
testing including consideration of scaling.
3 It is a difficult subject area but there is an awful 4
lot of data over a range of scaling and some full scale tests 5
of certain parts of the phenomena which require full scale.
6 A combination of all of those things by people who 7
make this their science let us conclude that while you still 8
will not be able to answer all of the questions, we have a 9
pretty good answer.
10 COMMISSIONER CARR:
All right.
One other question.
11 In your nuclear plant analyzer, how full is your data bank?
12 MR. MORRIS:
We have a problem with getting enough 13 data on plant design details to allow for a rapid analysis of 14 each and every plant.
For instance, we could not now set up 15 and run a transient for every plant in the country.
16 However, we are working to have that data bank grow 17 as we can by establishing plant decks.
18 MR. STELLO:
How many plants do you have the data i
19 for now that are in the analyzer?
20 MR. MORRIS:
Lou.
21 MR. SHOTKIN:
Four.
22 COMMISSIONER CARR:
Four types or four particular 23 plants?
24 MR. SHOTKIN:
There is one plant, the Zion plant, is 25 in there almost completely and then we have three other
I l
63 1
plants that we got a lot of data on the pressurized thermal 2
shcck program.
One was a Combustion Engineering, one a 3
Babcock and Wilcox and another, a Westinghouse plant.
We have 4
that data available to go intp the data bank.
5 MR. STELLO:
Don't you also have one BWR?
f 6
MR. SHOTKIN:
Yes.
We have some BWR but the data 7
bank software is not ready yet to take BWR data.
8 COMMISSIONER CARR:
Money limited?
9 MR. STELLO:
At the moment, I don't think so.
One 10 of the things we are attempting to do is to get distribution 11 of this knowledge and availability of this particular kind of 12 capability out to the industry and to others who also ought to 13 be willing and wanting to use it and make it available to
,(
14 them.
15 It is a product of research.
I think research has 16 pretty well finished up when they developed that tool and now 17 we are trying to get more widespread use.
So it is 18 encouraging the widespread use, not mandating it.
19 MR. BECKJORD:
May I go back to Commissioner Carr's 20 question?
21 CHAIRMAN ZECH:
Go ahead.
22 MR. BECKJORD:
On the scaling for these plants, I 23 can't speak to these specific facilities but I do know that 24 in projects I have been involved in the past, there is an 25 extensive use of dimensional analysis which enables you i
l l
o e
64 1
to change the relationship among variables so that you can get
<s 2
realistic hydraulic parameters and that has been used 3
extensively in the past and I am sure it was considered here.
4 MR. STELlo:
It was.
5 MR. BECKJORD:
But I will check into it.
6 CHAIRMAN ZECH:
Let me just comment that as far as 7
I am concerned nothing beats the full scale modeling.
I know a
it is very difficult and sometimes impossible unless we go to 9
real extremes, but certainly I think every effort to get the 10 information that perhaps is already available is worthwhile 11 and also at least think about perhaps some imaginative ways of 12 getting the best information ws can we can get available.
13 I agree that it is something that certainly is 14 something we ought to think about.
15 I just have one question.
It would appear to me 16 that we talked mostly about PWR plants.
You did mention an 17 experiment with baron mixing process for BWR's, but do we 18 conclude that you have so much more confidence with the BWR 19 plants that you don't have as many facilities or thermal 20 hydraulic initiatives going on in this area?
21 Maybe you could elaborate why the PWR's seem to get 22 so much emphasis.
23 MR. STELLO:
I think the short answer is because 24 that was the interest of the Federal government when it began 25 the commercial application of nuclear power through the
=
.i 65 1
Navy program which are PWR's and hence, there was a great deal 1
2 of activity related both to the code development and the 3
actual experimental work associated with PWR's.
4 Then as the commercial reactors developed late in 5
the 1960's and early in the 1970's, recognition to do more and 6
more testing on the BWR's started to come in.
But overall, it 7
is just clear because those are the facts.
8 There is significantly more testing sponsored by the 9
Federal government for PWR's than BWR's.
10 CHAIRMAN ZECH:
Should we be doing more in BWR's?
11 Should there be a better balance?
12 MR. BECKJORD:
May I respond to that?
13 MR. STELLO:
Go ahead.
,(
14 MR. BECKJORD:
There is a technical consideration.
15 In almost every transient that occurs in a BWR, the direction 16 is pretty clear.
I mean, you de-pressurize it because 17 de-pressurizing it both accomplishes that purpose and it also 18 cools the core down.
19 In the case of the PWR, the situation is a good bit 20 more complicated.
Because of its indirect cycle, the coolant 21 in the primary loop is transferring heat from the core over to 22 a heat sink which is the steam generator.
The problem in many 23 of these transients is maintaining that heat transport from 24 the core over to the steam generator.
25 In the case of the PWR, you want to maintain
~ - - - -
\\
1 66 i
1 pressure in the primary systems so it will continue to 2
function as a pressurized system so that the heat transport 3
can be effectively accomplished.
p It is this distinction which makes in this respect, 4
5 in the respect of loss of coolant accidents, the BWR'is a f
6 simpler machine than the PW'.
R 7
CHAIRMAN ZECH:
I appreciate that fact and I 8
understand what you are saying but perhaps just because it 9
started out with all of the effort on PWR doesn't mean 10 necessarily that perhaps we shouldn't be taking a different 11 look at BWR.
12 I see what you are saying but perhaps we should k
see if we are doing enough in that regard.
Maybe we are but I 13 14 am not so sure and I think it is worth thinking about.
15 MR. BECKJORD:
There is other work going on on some 16 BWR hydraulic problems which we can give you some advice on.
17 We didn't really cover that in this presentation.
18 COMMISSIONER BERNTHAL:
I think the very fact that 19 the principal question that is before us now on BWR's involves 20 containment and the rather small and less robust containments i
21 for BWR's points out what was perceived to be an inherent simplicity and inherent safety if you will of the BWR system 22 23 compared to PWR and I guess Vic says it is sort of in part 24 historical because it started out that way but it also can't 25 escape attention that the complex thermal hydraulic problems
67 1
appear to lie pretty much on the PWR side as opposed.to the 2
BWR side which has a different set of problems, one of which 3
is before us right now.
4 CHAIRMAN ZECH:
I just ask you to look at that as a 5
possibility that we need a little bit better balance.
6 MR. STELLO:
We will.
7 CHAIRMAN ZECH:
I think it is worth looking at.
Let 8
me just comment that I agree entirely with Commissioner 9
Bernthal's emphasis to the research people, too, about trying 10 to articulate your program.
I think his suggestion is 11 an excellent one.
12 Commissioner Bernthal on the Commission is obviously
'3 the one most qualified in research matters and I know he has
(
14 wrestled with this very question of how can you best present 15 the program and he has tried to assist his fellow 16 Commissioners in that regard, too, so I think his comments 17 are very well taken and I would suggest that you might want to 18 give some real considerable thought to that because i
19 presentation of the program, as I mentioned earlier too, is I 20 think extremely important.
21 Let me just express the Commission's appreciation 22 especially to Bill Morris and to Mr. Stello and to 23 Mr. Beckjord, also, for the very fine presentation today and 24 the informative briefing on our thermal hydraulic research 25 program.
r 68 e
1 I think it is very useful to have particular
,-~.
2 briefings like this to bring the Commission's attention focus l
3 on the research program.
I certainly would encourage the i
4 research staff to continue their efforts to work with industry 5
and also with our international partners in enhancing our 6
understanding of thermal hydraulics during accidents or other 7
difficult conditions.
8 I have had a chance during my recent trips overseas 9
to see first hand some of the research facilities that you 10 discussed here today.
I think our international partners are 11 indeed making a strong contribution to international safety 12 and I think our working with them is most appropriate.
13
(
I know that the Commission currently has before it 14 the staff proposed revisions to Appendix K to 10 CFR Part 50 15 and we will be considering these for a possible decision very 16 soon.
17 Are there any other comments from my fellow 18 Commissioners?
19 (No response.]
20 CHAIRMAN ZECH:
If not, we stand adjourned.
Thank 1
21 you very much.
22 (Whereupon, the Commission meeting was adjourned at 23 3:40 o' clock p.m., to reconvene at the Call of the Chair.]
24 25
i
\\
1 2
REPORTER'S CERTIFICATE 3
4 This is to certify that the attached events of a 5
meeting of the U.S. Nuclear Regulatory Commission entitled:
6 7
TITIZ OF MEETING: Briefing on Thermal Hydraulic Research Program (Public Meeting) 8 PLACE OF MEETING:
Washington, D.C.
9 DATE OF MEETING: Monday, November 10, 1986 1
10 11 were held as herein appears, and that this is the original 12 transcript thereof for the file of the Commission taken
{
13 stenographically by me, thereafter reduced to typewriting by 14 me or under the direction of the court reporting company, and 15 that the transcript is a true and accurate record of the 16 foregoing events.
17
d; ra-Il-1'L ; ^ -------
18
'^
Marilynn M. Nations 19 20 21 22 Ann Riley & Associates, Ltd.
1 23 i
e 24 25
l BRIEFING FOR Tile U.S. NUCLEAR REGULATORY COMMISSIO ON Tile THERMAL HYDRAULICS RESEARCH PROGRAM l
BILL MORRIS DIVISION OF REACTOR SYSTEMS SAFETY NOVEMBER 10, 1986 0FFICE OF NUCLEAR REGULATORY RESEARCH
OBJECTIVES OF PRESENTATION TO IDENTIFY THERMAL HYDRAULICS ISSUES O
TO DESCRIBE THE APPROACH USED TO RESOLVE THESE ISSUES O
TO DESCRIBE SPECIFIC PROGRAMS UNDERWAY TO RESOLVE ISSUES FOR 0
OPERATING REACTORS TO IDENTIFY THE REGULATORY IMPACT OF THEPMAL HYDRAULICS RE 4
o i
THERMAL HYDRAULICS ISSUES COMPLEX TRANSIENTS O
CONTINUED OCCURENCE OF COMPLEX TRANSIENTS AT OPERATING REAC AND THAT THERE MAY BE LIKELY COMBINATIONS OF EQUIPMENT MALFUNCTIONS, OPERATOP ER SYSTEM RESPONSE SUCH THAT SAFE SHUTDOWN CAN NOT BE ACHIEVED REC 0VERY FROM POSTULATED ACCIDENTS O
THERE ARE A NUMBER OF IDENTIFED THERMAL HYDRAULIC PHENOME CONFIPM ADEQUATE CAPABILITY OF PLANT SAFETY SYSTEM AND OPE MITIGATING POSTULATED ACCIDENTS SUCH AS LOSS OF COOLANT ACCIDENTS.
GENERIC ISSUES / REGULATION O
THERMAL HYDRAULICS CONSIDERATIONS HAVE BEEN SIGNIFICANT A NUMBER OF GENERIC ISSUES SUCH AS PRESSURIZED THERMAL SHOCK, THE ECCS P APPENDIX K.
l IS THAT THE BASIC PURPOSE OF THERMAL HYDRAULICS PESEARC I
T!!E BOTTOM LINE OF SEVERE ACCIDENTS.
4 e
J THERMAL HYDRAULIC RESEARCH APPROACH EMPHASIS IS ON SEVERE ACCIDENT PREVENTION THROUGH THIS INFORMATION IS USED TO ENSURE THAT O
DURING ACCIDENTS ANO TRANSIENTS.
PLANT EQUIPMENT, OPERATIONAL PROCEDURES AND TRAINING APE ADEQUATE TO WITH OPERATING EVENTS AND PREVENT SERIOUS ACCIDENTS.
l DIVERSITY IN PLANT DESIGN AND OPERATION AND THE DIVERSI POSSIBLE ACCIDENTS AND TRANSIENTS MAKE DIRECT EXPERIM O
WE MilST' DEPEND ON ASSESSED COMPUTER CODES TO IMPORTANT EVENTS IMPRACTICAL.
f ANALYZE EVENTS OF INTEREST.
ASSESSMENT OF COMPUTER CODES IS COMPLICATED BY SCALING QUESTIONS, OF SYSTEMS AND T/H PROCESSES AND THE PERIODIC IDENTIFI O
WHICH NEED TO BE SIMULATED.
A DUAL EXPERIMENTAL / ANALYTICAL APPROACH IS USED TO T i
CALCULATIONS ARE SUPPORTED BY COMPARISON WITH EXP O
PHENOMENA 0F INTEREST.
IN CODE PEER REVIEW IS FMPLOYED THROUGHOUT THE PROCESS -- IN TEST DESIGN, t
0 DEVELOPMENT AND IN CODE ASSESSMENT.
THERMAL HYDRAULIC TECHNICAL INTEGRATION CENTER AT INEL.
O h
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B&W OPERATIONAL TRANSIENTS ISSUES WHY ARE B&W PLANTS SPECIAL?
O BRW PLANTS HAVE A HISTORY OF COMPLEX OPERATING EVENTS.
INTEGRATED CONTROL SYSTEM, ONCE B&W PLANTS HAVE A NUMBER OF UNIQUE FEATURES (E.G.
THROUGH STEAM GENERATOR, AUX, FEEDWATER DISTRIBUTION, SMALL PRESSURIZE l
l I,
MAKE THE PLANT MORE DIFFICULT TO CONTROL DURING TRANSIENTS, NRC'S PWR SAFETY ANALYSIS CODES HAVE NOT BEEN ASSESSED F TRANSIENTS BECAUSE OF THESE UNIQUE DESIGN FEATURES.
ONLY LIMITED EXPERIMENTAL DATA EXISTS TO VALIDATE CODE C i
i PLANTS.
INTEGRATED EXPERIMENTAL PROGRAM 0
7 MIST PROGRAM WILL PROVIDE TESTS OF SMALL RREAK LOCA, NATURAL CIRCULATION i
f LIMITED STEAM GENERATOR TUBE RUPTURE AND FEED / BLEED TESTS.
l PLANNED FOLLOW-ON MIST PROGRAM WILL EXPAND TEST DATA TO OTHE
BAW OPERATIONAL TRANSIENTS - INTEGRATED EXPERIMENTAL PROG 1
LARGE SEPARATE EFFECTS TESTS ARE REQUIRED TO QUANTIFY HEA (PART OF CEC AT INEL)
CHAPACTERISTICS OF B&W ONCE-THROUGH STEAM GENERATOR.
NEW INTEGRAL FACILITY SCALED TO BETTER CHARACTERIZE A (PART OF CEC AT INEL)
REGARD TO BEHAVIOR DURING MANY OPERATIONAL TRANSIENTS.
AN INTEGRATED PLAN HAS BEEN DEVELOPED FOR THE MIST AND C SEEKING SUPPORT FROM DOE, EPRI AND B&W OWNER'S GROUP.
O ANALYTICAL PROGRAMS EXAMINING THE APPLICABILITY AND LIMITATIONS OF CURRENT AVAILABLE DATA.
INTEGRATED METHODOLOGY PROGRAM IS USING PRA, T/H CODES AND IIUMAN l'
ANALYSIS TO ASSIST IN THE REASSESSMENT OF B&W PLANTS.
i ASSESSMENT OF CODE CAPABILITY AND IMPROVEMENTS IS NEC
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IS GENERATED IN TEST PROGRAMS.
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,4 ANALYSIS FIRST PREDICTED 1981 FIRST SEEN IN SEMISCALE TEST S-UT-8 1982 COMFIRMED IN SEMISCALE TESTS S-LH 1984 RE-CONFIRMED IN LARGE SCALE ROSA-IV TESTS 1985
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- COOLING, DUE TO UPI PENETRATION.
1 l
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e 2D/3D (CCTF) TEST RESULTS, AND BEST-ESTIMATE PWR CALCULATIONS SHOW:
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i PROPOSED ECCS RULE REVISION i
THE STAFF IS PREPARING A REVISION OF 50.46 FASED ON EXPERIENCE USI 0
SECY-83-472 APPROACH.
ECCS PERFORMANCE CALCULATIONS WOULD BE MADE USING REAllSTIC METHO l
0 EXTENSIVE ECCS RESEARCH RATHER THAN CONSERVATIVE APP.ENDIX K METHOD UNCERTAINTY ESTIMATES WOULD BE REQUIRED TO PROVIDE A HIGH PROBABIL THE 2200 F PEAK CLAD TEMPERATURE LIMIT AND OTHER CRITERIA WOULD NO 0
SIGNIFICANT ECONOMIC BENEFIT IS EXPECTED TO RESULT.
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NO NET REDUCTION IN SAFETY is EXPECTED.
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USED TO IMPROVE PLANT DESIGN AND OPERAfl0N.
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ECCS SETP0lNTS BASED ON REAllSTIC THEPMAL HYDRAULIC BEHAVIOP l
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THE TIC STAFF IS AVAILABLE FOR PRIORITY STUDIES BY SHIFTING FROM ONGOING O
RESEARCH PROGRAMS.
THESE ONGOING PROGRAMS ENCLUDE:
CODE IMPROVEMENT AND NA!NTENANCE CODE APPLICABILITY TO FULL-SCALE LWR'S NUCLEAR PLANT ANALYZER EXPERIMENTAL SUPPORT i
O THIS YEAR PRIORITY STUDIES INCLUDE:
ECCS RULE REVISION BaW INTEGRATED METHODOLOGY (T/H, PWR, HRA)
CROSS-COMPARISON DF B&W, W AND CE PWR'S WITH RESPECT TO CPITICAL FUNCTIONS TO BE PERFORMED BY OPERATORS DURING OPERATIONAL TRANSIENTS.
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Work Structure Related to the Technical Integration Center Act vit s nd NRC l
~~~~~~~~~
I Other F-------~ Coordination Across Technical Disciplines i
Code Ongoing Priority A
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