ML20247D412
| ML20247D412 | |
| Person / Time | |
|---|---|
| Issue date: | 04/21/1989 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| ACRS-T-1733, NUDOCS 8905250409 | |
| Download: ML20247D412 (187) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS
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4 In the Matter of:
SUBCOMMITTEE ON INSTRUMENTATION
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AND CONTROL SYSTEMS
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O Pages:
1 through 135 l
Place:
Bethesda, Maryland Date:
April 21, 1989
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HERITAGE REPORTING CORPORATION
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.t' PUBLIC NOTICE BY THE 2
UNITED STATES NUCLEAR REGULATORY COMMISSION'S 3
ADVISORY COMMITTEE ON REACTOR. SAFEGUARDS 4
t 5
6 7-The contents of this stenographic transcript of the 8
proceedings of the United States Nuclear Regulatory b
9 Commission's Advisory Committee on Reactor Safeguards (ACRS),
10 as reported herein, is an uncorrected record of the discussions 11 recorded at the meeting held on the above date.
I 12 No member of the ACRS Staff and no participant at-13 this meeting accepts any responsibility for-errors or
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inaccuracies of statement or data contained in this transcript.
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UNITED STATES NUCLEAR REGULATORY COMMISSION l '.
' ADVISORY COMMITTEE ON REACTOR SAFEGUARDS In the Matter of:
)
)
SUBCOMMITTEE ON INSTRUMENTATION.)
AND CONTROL SYSTEMS
)
- Friday, April 21, 1989 Room P-110, Phillips Building j
7920 Norfolk Avenue j
Bethesda, Maryland The meeting convened, pursuant to notice, at' 8:30 a.m.
ACRS MEMBERS PRESENT:
1 DR. WILLIAM KERR
(
. Subcommittee C,hairman Professor of N,uclear Engineering
()
and Director of the Office of Energy Research, University.of Michigan.
i Ann Arbor, Michigan MR. JAMES' CAR 80LL Retired Manager, Nuclear Operations Support Pacific Gas &, Electric Company San Francisco, California MR. CHARLES J'.
WYLIE Retired Chief Engineer Electrical Division Duke Power Company Charlotte, North Carolina i
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r DR..HAROLKD W.. LEWIS Professor.of Physics, Department of~P'vsics University of. California Los Alamos, California ACRS COGNIZANT STAFF MEMBER 1 M.
EL-ZEFTAWY.
.AC_RS;CONSU.LTANTS1
. PAUL' DAVIS LESTER'OA'KES WALTER LIPINSKI
. PRESENTERS; (BWR. OWNER'S GROUP) & others-DAN WILLIAMS RICHARD BARNES STEVE FLOYD ROGER NEWTON
'MELITA OSBORNE (W) l.
BILL SULLIVAN W.
STALTER PRESENTER'S1 (NRR STAFF)
H. LEE F.
FIENO Z.
MAUCK H.
LYNCH' hJ..
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3 DR. KERR:
The meeting will come to order.
4 This is a meeting of the Advisory Committee on 5
Reactor Safe Guards, the Subcommittee on Instrumentation and 6
Control Systems.
7 My name as Kerr.
I am Subcommittee Chairman.
B Other committee members present today are Messrs Lewis and 9'
Wylie.
We expect Mr. Carroll and as consultants, we have 10 Messrs Davin~, Lipinski and Oakes.
11 The purpose of the meeting today is to review the
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112 implementation and status of the ATWS Rule.
I must
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13 emphasize that this is not a meeting to discuss ATWS.
ATWS 14
.has been resolved. What we are discussing is the reliability 15 of the shutdown system.
16 Mr. Medhat El-Zeftswy is the Cognizant ACRS Staff 17 Member f o r-this meeting.
-18 Rules for participation at todays meeting were 19 announced as part of the notice of the meting publishea in 20 the Federa) Register of Monday, April 3d, 1989.
21 A transcript of the meeting is being kept and will 22 be available as stated in the Federal Register notice.
23 I ask that each speaker identify himself or 24 herself and use a microphone so that your words can be 25 recorded accurately, f'V)
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We W111' proceed with the meeting, bu t bef ore going 2
to the' representatives of the NRC staff, I would ask if 3
there are any comments or items in which any of you would f
4 like special emphasis?
5 (No. response) 6
-To paraphrase Mr. Churchill, never have so many 7
depended upon so little for so much as is the case with the G
reliability, or lack of availability, I should say, that we
'9 demand for the automatic shutdown system, sometimes known as 10 the SCRAM system for reactors.
11 The resultant core damage probability, for 12 example, depends upon this very low lack of availability and f._
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-33 it therefore behooves us to, I think, continually follow
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14 experience and our best judgment to ascertain, insofar as we 15 can determine that we are achieving the reliabilities that 16 are generally assumed.
17 So today, specifically, we want to explore the 18 changes that have recurred as a result of the ATWS Rule 19 adopted some years ago and to acquire any additional 20 ~
information that may bear upon this important system in 21 operating reactors.
22 I believe that Mr. Lynch is going to open things.
23 MR. LYNCH:
That's correct, Dr. Kerr.
24 DR. KERR:
Okay.
25 MR. LYNCH:
I'm Dave Lynch, I am lead Project Heritage Reporting Corporation (202) 628-4888
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1 Manager on this particular issue and I would like to just 2
mention a few administrative details.
3 There are copies of the staff's slides available 4
up front.'They come in three separate sets.
If anybody does 5
not get a' copy, I do have a few extras here with me and, if 6
need be, I can duplicate some more.
I have the masters 7
also.
8 I would like to make a slight editorial correction 9
to the agenda,.as passed out.
For Roman III, Scott Newberry 10 will not be making that presentation, Dan Fieno will be 11 doing Roman III (a), the effect of BWR instability on the 12 ATWS fix--I'm sorry, Harry Richings wil'. be and for Roman
-.()
13 III(b), Dan Fieno, who will be doing the effect of the i
14 impact of high core burn up on the ATWS situation.
I 15 Now with respect to the staff's presentation, we be going in three separate groups, consistent with the
'16 will l'
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17 three packages of slides I have laid out on the chairs.
i 18 The first person to start off for the staff is
'19 Scott Newberry, who will introduce the general background 20 and then turn it over to members of his staff.
l 21 DR. KERR:
Thank you, Mr. Lynch.
22 MR. NEWBERRY:
Thank you Dave.
23 My name is Scott Newberry. I am Chief of the l
L 24 Instrumentation and Control Systems Branch in NRR.
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25 We're glad to be here, Dr. Kerr, to discuss the Heritage Reporting Corporation (202) 628-4888 i-
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'l statuc of ATWS imp ~1ementation with you. We share your views j
2 on the im 3or t.ance of this issue.
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Since NRR reorganized in the Spring of
'87, we 4
'have placed considerable. resources, resolution of issues
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remaining to implement the ATWS Rule systems, to review each e
of the plant specific' designs with respect to their i
7 implementation and I would estimate, that on the order of a 8
third of my branch, at one time or the other, is working on
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9' ATWS, out of the approximately 9 or 10 engineers in the 10
. Instruments tion and Control Systems Branch in NRR.
11 We are prepared to go through the agenda item by 12 i tem.
Hulbert Lee, from my branch, will be making the t
13 presentation.
14 I would comment that the last item, under Roman
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15 Numeral II, on SWR resert pump trip failures, that appears i
16' to be a new item on the agenda to us. We aren't formally 17 prepared te discuss that, but we are certainly familiar i
T. 8 with, what I expect is your concern, and would be glad to 1
19 talk about that and answer any questions that you might 1
20
- have, j
I 21 I have several members of my branch here today. As 22 I said, Hulbert Lee would be making the presentation. Jerry
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23 Mauck, Vince Thomas and Lynn Tran. who are also working on 24 ATWS are here today to answer any questions.
Hulbert.
I 25 MR. LEE:
Good morning.
My name is Hulbert Lee, i
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trom the Instrumentation Control Branch.
I am one of the 2
reviewer on ATWG design review and implementation.
3 First let me go through, briefly, the 4
chronological] background since the ATWS Rule was published 5
in 1984.
6 In 1985, April, NRR issued QA guidance to go 7
through Genetic Letter 85-06, basically telling industry the 8
guldance on the ATWS related to component because it was non 9
safety related, so we had specific guidance how to deal with 10 the QA requirements.
13 In May, 1985, N>RR established at Mul ti-plant 12 Action that basically started the review effort.
Each
(-)
13 different vender-owners group submit their genetic design 14 package.
1.5 September Owners Group submit report CEN 315.
B&W 16 Owners Groups submitted their genetic report October and 17 Westinghouse submit in October and the Boiling Water Reactor 18 Owners Group submitting in January.
19 DR. KERR:
Mr. Lee, unless there is something 20 unusual about this schedule that you want to point to, why 21 don't we just assume that we can read the schedule and you 7
.go on'to your next slide.
22 23 MR. LEE:
Okay The only thing I want to point to 24 is the B&W Owners Group Report Review, a little bit delayed 25 because the staff resource work on the B&W Reassessment Heritage Reporting Corporation (202) 628-4888
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1 Program and'the Rancho Seco restart, so the acceptance of
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2 the genetic design review, there was a little bit delay on 3
that.
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Another point I want to point ou t is so far the 1
5' status, we have 82 SER complete-and 30 plants have been 6
. inspected.
That is based on our telephone survey through 5 7
different regions.
It may change from month to month if you
.8 do' progress.
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9 DR. KERR:
Inspected means that somebody inspec ted 10 them.
13 MR. LEE:
Yes.
12 DR. KERR:
Who does the inspecting?
()
13-MR. LEE:
The region inspector.
Each region set 14 up special task force effort to go through each plant 15 specific implementation.
16-DR. KERR:
What do they inspect?
17 MR. LEE:
We have guidance issued, TI 25---
18 DR. KERR:
My question is: Do they inspect 19 documents or do they go and look at equipment?
20 MR. LEE:
Both all the procedures, documents and 21 the equipment itself.
22 MR. NEWBERRY:
I think that we could clarify a 23 little bit further there that each plant specific design is 24
' looked at. closely by headquarters and the results of that 25 review are documented.
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'l In the Safety Evaluation, as Hulbert has indicated
'2 there,-we're just about completed with our review of each 3
plant specific design.
After we complete our review, 4
especially in areas like diversity, getting right down to-5 the specific details of the hardware, the inspectors in the 6
regions, supported by headquarters will go out and look at 7
both the equipment, maintenance procedures and any.open 8
issues that the u tility was supposed to take care of after I
review and every plant will be 9
we had performed our 10 inspected.
l 11 MR. LIPINSKI:
What about the issue of simulators, 12 is that included in terms of whether the operators are being 13 trained?
14 MR. LEE:
To my knowledge, probably is not.
15 MR. NEWBERRY: Well, Mr. Lipinski, not really in 16 the scope of this program.
Within the scope of EOPs and how 17 these systems would, you know, after their installed in the i
18 p 3 a n t', I would expect that the answer to your question is 39 yes.
I don't think we're the group to--
20 MR. LIPINSKI:
Who closes that loop?
21 MR. NEWBERRY:
I believe tha operator licensing 22 people who do the EOP inspections, the simulator inspectors, 23 would close that loop.
That is--
.24 MR. LYNCH:
We can get back to you on that 25 specifically, but I think, as Scott has indicated, that will
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be the normal practice.
We would not take ATWS simulation 2
and traini ng and break that out as a separate subject. We 3
.would rather keep the operator licensing qualifications and 4'
all the other human f actors considerations with respect to r
.5 the plant, including the simulator in one package.
-6 DR. LEWIS:
I wonder if I could raise a different 7
question,.when this one is over?.
8 At some point, during the day, I want to ask a i
o-question about diversification or diversity and you use the l
10 Lerm.
I wonder if you'll tell me a good time.
Is this a
. 1'1 good time to raise it?
12 MR. LYNCH:
We have a specific slide on that
.h)..
' subject and that would be an appropriate time.
It's coming 13 14 up if you look at the package.
. 15 DR. LEWIS:
Soon?
16 MR. LYNCH:
- Yes, i
17 DR. LEWIS:
I can hold myself.
18 MR. LEE:
This table provides a summary of the 19 implementation status for boiling water reactor and most of
.20 the plan is already implemented with few coming to be 21 implemented this year and this too is basically the Browns 22 Ferry type'of restart.
23 For the Westinghouse plant, we have other 55 24 plants, 20 already complete implementation and 16, a good 25 portion will be completed by the end of this year.
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-1 The CE plant, start a little bit late, but we
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tried to' improve the schedule on the implementation.
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The B&W plant, although this shows there is no 4
implementation complete so far, some of the equipment 5
related to the DSS and AMSAC are already installed.
They 6
Just have not total]y completed review and the procedures to 7
utilize those systems has not been ut into the plan, so we i
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cannot declare implement.
9 So this table basically is from the record of each
~10 project:that they are completed implementation and actual
'l l equipment is installed better than this table shows.
12 Another point I would like to point out is that h(_)
13 for Poiling Water Reactor we take the first implementation L
14 review, so most of the Boiling Water Reactors, they install
-15 equipment much earlier than the PWRs.
16 MR. LYNCH:
If I may interrupt for a moment to 17 expand on something that Hulbert said.
18' We hold a fairly rigid standard on what 19 implementation means and as Hulbert says, the hardware may 20-be in, bu t we don' t give credit f or implementation until the 21 procedures have been revised and the operators have been 22' trained on those revised procedures.
23 So you might have the situation where every piece 24 of hardware is there, but if the operators haven't completed 25 their training, we don't give credit for implementation.
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1 MR. DAVIG:
Excuse me.
Mr. Lee, can you tell me 2
-which-BWR was exempted from the resert pump trip and what 3
the basis was, briefly, for the exemption?
4 MR. LEE:
It's a very good point.
Because the 5'
size'and'their unique desigr. and the location, there was 6
new guidance.
7 MR. NEWBERRY:
I think that exemption is a 8
proposed exemption.
Correct Hulbert?
I don't think we have 9
quite finished our review.
10 MR. LEE:
Yes.
The resert pump trip is already IJ approved, yes.
The ARI is still under review.
12 The open issues and NRC staff positions, the first
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'13 one I am going to discuss is the BWR plants instrument 14 diversity.
15 The background, as mentioned earlier, for BWR, 16 we take post instrumentation review.
We give a check list 17 to each utility, ask them to verify the conformance to each
'18 individual design criteria and then during the inspection, 19 stage, we verify each items.
20 This issue was discovered during a test spec 21 updating review for Brunswick.
In their original submittal, 22 they declared all diverse and when we review the test spec 23 modification, we found out same model, the analog 24 transmitter trip unit was utilized at both the execute 25 system and ARS system.
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DR. KERR:
l'm sorry, what you're saying is that 2
they didn't install what they had proposed to install?
3 MR. LEE:
They already--At Brunswick, it's in the
.4 process.
They're 1nstalled and--
L 5
DR. KERR:
No.
I thought you said they or3ginally 6
proposed diverse systems, but when you inspected you-7 discovered they had not installed diverse systems.
Did I 8
misunderstand?
9 MR. LEE:
In their submittal for the compliance 10 with ATWS new guidance, they identified what is diverse and 13 then when we reviewed the tech specs and during the 12 inspection, we found out they're not the same model of the
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13 ATTU-u tilized on both systems.
14 MR. NEWBERRY:
It was the view of the plant that 15 the equipment they had installed, although they're the same 16 model, HETU, was diverse and Hulbert will describe that.
17 It's primarily because of in ARI, they are energized to 18 actuate inter active trip system, deenergized to actuate.
I 19 They viewed that the diversity of function was sufficient to 20 meet the rule.
We disagree.
21 DR. KERR:
So that is a judgment call?
22-MR. NEWBE.RRY:
Yes, sir.
23 DR. KERR:
And you're convinced by having them 24 install something different, it will be significantly more 25 reliable?
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1 MR. LYNCH:
I don't know that we can say that, 2
sir, so much as we're saying that the overall phijosophy of l
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the ATWS Rule is.to minimize common mode failure by 4
implementing diversity and by having an exactly the same 5
model component, sub component for sub component in that
'6 trip unit, we believe i t somewhat tends to short circui t the 7
concept of diversity of components.
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'DR.
KERR:
But if that is the overall philosophy, 9
then I don't understand'it because it seems to me that the 30
.overall philosophy.should be one which tries to have low 13 risk.and high reliability and I don't understand a 12 philosophy that ignores reliability and risk and instead t -
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seeks to talk about something like diversity and NRC 14 philosophy.
15 DR. LEWIS:
This is what I was going to bring up 16 at a cer tain point because as I looked ahead to the view 17 graph, it simply states flatly What you have just said, 18
- namely that to minimize the probability of commoi mode 19 failures, one insists on complete diversity and it is easy 20 to conclude from that, and this has, in fact, strengthened 21 the conclusion, that if one had a really very fine component 22 and.used it in two places, you would require that it be 23 replaced in one of those locations with an inferior 24 component, just to satisfy the blind thrust toward 25 diversity.
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Where as, what I think our chairman is saying is I
2 that o'ne ought to look somehow at the probability of common 3
mode. failures and make an effort to' improve the overall 4
reliability of the system, which is sort of the way I would F:
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.6 And I wondered, Just how far you would take this.
6-7-
You know, there are resistors that are replicated through n
8 tIhe system.
There.are screws that are replicated through F. -
9 the system that come from suppliers.
10 If you ' re really blind abou t a requirement f or h
~11 diversity, you would go crazy.
'12 MR..NEWBERRY:
That's true.
The regulation does f-
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require independent and diverse components in the reactor 4,j 13 14 trip system and alternate route interjection or diverse 15 SCRAM systems to a reasonable and practical level.
16 So there is a judgment call that needs to be made 17 and--
18 DR. LEWIS:
But the view graph that we are coming 19 to, when I am supposed to bring this subject up, doesn't say 20'
'anything about reasonable.
21 MR. NEWBERRY:
Well the guidance that was 22 published with the rule does and this has been a point of 23 contention between he staff and the BWR Owners Group since, 24 I guess, the middle of last year and we can go into it in 25 more detall here, if you would like, but it was our view Heritage Reporting Corporation (202) 628-4888
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that, not only because of these components being virtually 2
identical, but also because there was a ready replacement 3
~from a different manufacturer, that it was reasonable to 4
replace these ATTUs.
5 DR. KERR:
But it had nothing to do with 6
eliability, it just had something to do with diversity?
7 MR. NEWBERRY:
No, I wouldn't say that.
I think 3
jL does have something to do with the reliability but I 9
don't know that I could quantif y f or you, in really a
-10 rigorous way, what the significance of that change in 11.
reliability-would be.
12 DR. LEWIS:
Nobody, I think, is looking for rigor
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13 here, we're looking for plant safety and it may have been a
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14 point of contention between you and the owners groups last 15 year, whatever you just said, but I remember raising the 16 question 5 years ago or whenever the ATWS Rule first came 17 out and the example I used, I remember at the time, was that JS one would make that argument to say that every airplane r
19 should have--twin engine airplane should have one jet engine 1
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L 20 and one propeller engine for diversity because you could fly i
21 on either engine and that way you're certainly avoiding 22 common failure to the two engines and that is dumb, of 23 course.
Nobody does that because there are certain 24 advantages in duplicating components.
The maintenance 25 problems become easier, the parts problems become easier, nk) l Heritage Reporting Corporation (202) 628-4888 i
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-the experience-accumulates at twice-the rate, all sort.s of 2
things like that and they have to be quantified if you're
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really interested in plant safety.
4 MR. LYNCH:
You're absolutely right, sir.
But I 5
would like to throw a different point of view on the table 6
for your consideration.
7:
What we're talking,about--
-8 DR. LEWIS:
Go ahead.
9-MR. LYNCH:
What We're talking about is plants 10 that have a 40 year life time and, as you know, industry and 11 the NRC is presently reviewing the concept of a 20 year 12 extension, so we're potentially talking about plants with J~ s.
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F 13 very very long lives.
j 14 The concern that the staff has is: Will identical 15 units, down for the serial number, be such that during 16-their, say as-much 40 to 60 year life time, have a failure 17 due't.o an aging process that nobody can identify at this 18 po]nt?
And the thought was, the particular ATTU unit, if 19 that is replicated in the ARI circuitry as well as the RPS 20 circuitry, is not the only reliable component available to 21 industry, but the other components, which are used, in ATWS 22
~ circuitry in other plants are considered just as reliable so
.23 we don't want to get into a discussion about which vender's 24
.model is more reliable.
25 We won't take a position that this particular ATTU O'
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OUr concern is for 2'
ireohanisms which we cannot identify and the scenario is 3
aging of a particular component such that we would have a i
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fuel run, say of an 18 month duration, and in between a
-5 surveillance test, that they both come to the end of their 6
operating life due to aging, we don't really wish to address I
7-
'that question and by getting diversity between venders, we 8
hope that we can minimize that probability and that is what
-Q we are'really looking for in terms of the diversity of the 10 component level.
31 Certainly not down at the resister or the screw-12 level, but certainly for a black box package.
((
13 DR. LEWIS:
I don't want to belabor the point, but 14 I must say that I am not convinced because What you have 35 described is a perfectly reasonable quantitative approach to l
16 the diversity question, mainly that you have to ask yourself 17 what are the afflictions that are common to a particular 18 thing and see whether the overall contribution to risk is 19 larger because you have identical components.
20 But that doesn't seem to be what is happening.
21 What is happening is a fairly, as I understand it, is fairly 22 blinded here as to the requirement that, by golly, there 23 shall be different suppliers and different units.
24 MR. LYNCH:
Well sir, there is more than one 25 vender and we don't believe we're pushing industry O
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1 unreasonably hard by requiring that two reliable units from i
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separate vendors be installed.
There is more than one car 3
manufacture, there Is more than one airplane manufacturer 1
4 and there is more than one ATTU manufacturer and they're off 5
the Shelf components.
6 DR. KERR:
Mr. Lynch, it does not seem to me that 7
you should worry about from what vender a purchase is made.
8 That is irrelevant to reliability.
9 What we're trying to achieve is reliability and to 10 try to force a utility to buy from two separate vendors just 13 because there are two separate vendors in the market, it 12 seems to me, is irrelevant to what we ought to be talking ia-(
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'about.
I. don't understand that argument.
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14 MR. NEWBERRY:
The argument is not necessarily the 1
1 15 vendor.
I believe the argument is--
16 DR. KERR:
I'm listening to the argument that I 17 heard.
18 MR. NEWBERRY:
Yes, sir.
Just clarifying what Mr.
19 Lynch said, the argument is to reduce or minimize the chance 20 of an equipment failure due to a defect in the manufacturing 21 process or the design process of like components in analog 22 transmitter trip units.
23 These trip units are used in all pressure and 24 level channels in-the entire reactor trip system and 25 alternate route injection systems.
And what we were looking ps)
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for and it seemed to be reasonable, were different trip 2
unit.s in the ARI system.
3 MR. LIPINSKI:
But what we're not hearing is the 4
fact that you have compared these in any Way to show that 5
they have, at least, equivalent reliability. You may have 6
another manufacturer, bu t his uni t may have a failure rate 7
10 or a 100 times higher than the one he is using.
8 MR. NEWBERRY:
That's true.
9 MR. LIPINSKI:
The question is how do you 10 establish that?
11 MR. NEWBERRY:
That's true, sir, but the rule 12 Itself, for example, has the no requirement on safety ib
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13 related components, bu t i t does say that the components 14 should be reliable and we're depending upon industry to 15 properly interpret what reliable means.
16 We're not really--and, Dr. Kerr, you're quite 17 right.
I am not trying to force -We're not trying to force 18 industry to purchase from two different vendors.
If a 19 vender had two or three models that were sufficiently 20 diverse between models, we would certainly accept that.
The 21 concern is, again, to go back to the aging problem, a 22 particular design of a unit, both of which are identical, 23 What We're saying is that we could not address the 24 probability of them not having a common mode failure 25 mechanism sometime in the distant future, which we have no
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way at. all of identifying, until they accumulate the service 2
life that Would give us those statistics.
3 DR. LEWIS:
There is a battle in the super market 4
business to provide as much diversity as possible in j
5 packaged dry cereals in order to fill up shelf space at super markets and to do that, manufacturers put things in t.,
7 different size boxes, you know, pound to pound and a 8
quarter, pound and an eighth, different colors to occupy 9
shelf space.
10 The manufacturer, once he gets on to this game can 11 do that with different models, you know.
You can make minor 12 changes, give them different names, give them different n()
13 outside covers, you know.
14 At what point do you decide that something is 15 functionally sufficiently diverse to provide an enhancement 16 in safety compared to the real advantages of 17 standardization.
18 You know, the agency at another level is pushing 19 toward standardization of nuclear plants and here you have a 20 rule that is pushing against it because of safety reasons, i
21 you know.
Where are we?
22 MR. LYNCH:
Maybe We should go ahead. I share your 23 concern, but I don't know what else we can say.
24 DR. LEWIS:
No. It's been going on for a long
/
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MR. LIPINSKI:
Let me inject one last comment.
"?
The holy grail of diversity cannot be quantified.
3 So far I have yet to see some systematic process that tells 4
you what the benefits are statistically or any other way, 5
whereas, if we look at reliability of individual components, 6
we can quantify those numbers by collecting data on L
7 sufficient number of units.
8 Bu t when we say we're goi ng to have diversit.y, I 9
have yet to see some way to quantify what the benefit is.
10 We think we're getting something, but there is no way to 11 demonstrate'What that something is.
12 DR. LEWIS:
I agree with that.
As Bill says, r'g
'( j 13 we've been saying this for years, with no apparent affect.
14 DR. KERR:
Please continue, Mr. Lee.
15 MR. NEWBERRY:
One further comment.
I think the 16 subject of diversity in our reviews has been a dif ficul t one 17 for us.
The Judgments largely have led us to this point
.18 where we'r'e down to a couple of issues of disagreement.
19 This is one and there is going to be another one.
20 I think, getting back to one of Mr. Lipinski's 21 questions on reliability, I believe that everything that we 22 have seen so far would indicate that Rosemont Analog 23 Transmitter Trip Units are, indeed., reliable. They're widely 24-used in the i ndustry and have a very good record, but the 25 iole is rather prescriptive and--
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DR. KERR:
I thought that it had some language in 2
it that i ndi ca ti ng reasonableness, from what I heard
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3 otherwise, and you did indicate that there was a diversi ty i
i 1
4 of function and it is function, after all, that we're i
5 looking for from t,hese components, not just being there.
6 MR. NEWBERRY:
Diversity of function, from the 7
standpoint of movement of the switch position,.which changed
'8 the f unction f rom energize to de-energize, other than.that, 9
the boards are identical, yes, sir, that is correct.
10 And I think what you see here is the results of 11 our judgment and maybe we ought to move on.
12 MR. LEE:
The second issue also relates to the I
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(
.13 diversity of requirements on the newer CE plants.
14 Again we comment on the implementation aspect that
-15 followed the rule guidance, so we found some of the 16 components which were used in the reactor trip system and i
17 used for the AMSAC System and that, in our mind, that does 18 not satisfy the ATWS Ru]e diversity requirement.
19 The CE Owner's Group argument basically say those 20 are not cost effective.
The benefit is marginal, but our 21 position is that the cost benefit argument, has already been l
22' considered during the rule making process.
23 In the first case, we just followed the rule 24 guidance to make sure the implementation is following the 25 guidance published in the ATWS Rule Guidance, Heritage Reporting Corporation (202) 628-4888
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MR. LYNCH:
If I may interrupt for a moment.
The 2
slide doesn't say it, but those exemption requests were 3
denied a few weeks back, officially on the dockets.
4 DR. KERR:
Would you say that the diversity that 5
is being required will make the system more'or less 6
complicated than otherwise would be the case?
7 MR. NEWBERRY:
Anytime.you add something to a
-8 plant, I.think you may have the tendency to make it a bit 9
more complicated.
That appears to be the case here.
10 Certainly the view of the owners and the vender is 11 something that we are looking at closely now.
There is a 12.
continuing.need here, with respect to providing water to the
)
13 steam generator or, in some cases, for line breaks, 14 isolating water to a steam generator and.that tends to lead 15 you to some complexity in the design, yes.
16 DR. KERR:
This is for what we might call an 17 emergency.or auxiliary feed water?
18 MR. NEWBERRY:
Yes, sir.
This would be for the 19 actuation of the emergency or auxiliary feed water.
20-DR. KERR:
And this is automatic actuation--
21 MR. NEWBERRY:
Automatic.
2?
DR. KERR:
--as contrasted with--
23 MR. NEWBERRY:
That's correct.
24 DR. KERR:
Manual actuation is still available but 25 is not credited or is that--I mean credited in the sense Heritage Reporting Corporation (202) 628-4888
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that If one does an analysis does an analysis to determine 2
wha t. risk exists on a quali tative basis, one does not take p
3 into account the possibility of manual actuation.
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MR. LYNCH:
There is always a time delay that is 5
factored in to an analysis of manual actuation and to the 6
ex t.e n t that you increase the manual action to a 5, 10 or 15 L
7 minute period, you may be beyond the scope of the transient 8
by--
p i
9 DR. KERR:
But with it manually actuated a few 10 seconds, Hit would probably work?
i' 11 MR. LYNCH:
Yes, sir.
12 MR. NEWBERRY:
Oh yes.
IT.
, ;k_)
13 DR. KERR:
Thank you.
14 MR. WYLIE:
Let me ask a question.
These non 15 diverse components that are being used, are they performing
- 16 essentially the same functions in the several trains?
- 17 MR. LEE:
Yes.
Most relays, the relay matches.
18 MR. WYLIE:
Okay.
19 MR. LEE:
The next slide I am going to discuss is 20 the--
'21 MR. NEWBERRY:
'Hulbert, before you proceed, just l
22-to put where we are in perspective with the agenda, the 23-committee had asked to us talk about open issues on our j
24 reviews.
The issue of ATTU diversity and the issue, on a 25 few of the newer CE plants, on diversity of the AMSAC
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.1 feature are really the only two generic issues that are in 2
front of us right now.
Everything else is pretty much 3
status of plant specific implementation.
4 So unless you have any other questions, Hulbert is 5
going to get into the next agenda item on the meaning of 6
independence and diversity.
7 DR. KERR:
Thank you, sir.
8' MR. LEE:
The meaning of independence from ATWS 9
Rule guidance ~ states, " Logic and actuation device power must 10 be from an instrument power supply independent from the 11 power supplies for the existing reactor trip system."
12 The guidance also provides another provision,
,m()
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'" Existing reactor trip system sensor and instrument panel 14 power may be used provided the possibility of a common mode 15 failure is prevented."
16 But the staff position is--
17 DR. KERR:
Excuse me, do you understand what that 18 last statement means because I don't.
19 MR. LEE:
The next slide, I try to show what we l
l 20 interpreted from this guidance.
21 DR. KERR:
So you do understand what it means.
22 Okay.
23 MR. LEE:
But based on this guidance, we have two 24 methods of compliance.
25 The first is--
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DR. KERR:
I want to know what you think you're 2
comp]ying with.
This says that you're going to make this 3
such that the possibility-of common mode failure is 4
prevented which, I assume, means that the probabili ty is 5
zero, is that what that means?
6 MR. LEE:
Yes, it's just that you advance--it 7
could mean minimize.
8
.DR.
KERR:
Okay.
And what does minimize mean?
9-MR. LEE:
Well, due to engineering best judgment 10 to reduce'that probabi'lity from--
11 DR. KERR:
So it means use good engineering 32 judgment?
(_)
13 MR. LEE:
Yes.
14 DR. KERR:
Okay.
15 MR. LEE:
So the first one is preferred method of 16 design.
Use of total independent non 1-E power and if they 17
.have to share the power from 1-E power source, then the
'18 acceptable level is the DSS and AMSAC should be Class 1-E 19 system and also provide a failure mode effect analysis to 20 demonstrate the possibility of common mode failure is 21.
prevented.
22 We are illustrating with two simplified diagrams.
23 DR. KERR:
And again, when prevented is used here, 24 it doesn't mean prevented, it just means made reasonably
.gs 25 small.
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MR. LEE:
Yes.
2 DR. KERR:
And what is reasonably small, 3
engineering judgment?
4 MR. LEE:
Yes.
Our branch- -
5 DR. KERR:
Whose engineering judgment, the 6
. designers or the NRCs?
L 7
MR. LYNCH:
Well obviously, there
.,e two points 8
of view, industry has theirs and we lu a ours.
But 9
basically what we are statany as our position today.
10 DR. KE i:P So a licensee, from this, does not have 11 any :. dea wir tiier something that he presents will be i;
acceptable to NRC because he doesn't have any guidance as to n
1 V'
i.
What.is meant by " prevented."
14 Only when he submits it and a reviewer goes over 15 and.the' reviewer doesn't have any guidance either because 36 he's told to prevent it.
17 MR. NEWBERRY:
The guidance is primarily not in 18 the terms of definitions of " prevent" or " minimize".
The 19 guldance is primarily in the terms of design concepts, in 20 terms of whether the system is a non 1-E or 1-E or whether 21 the power supply should be independent or not independent
'22 from the reactor trip system power supplies.
23 The question comes up, for the designer, should'I 24 use the instrumentation buses that are used for my reactor 25 trip system to power the AMSAC or DSS or should I power that
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system from another bus and so, from a practical design 2
point of view, what Hulbert is going to show you here is our 3
view of what independence means when it comes to where you 4
would get the power these systems.
5 DR. LEWIS:
But what it says on he view graph, 6
the previous one, is that an Ff.EA is required to demonstrate 7
the' possibili ty of cvnmon mode failure is prevented and we 8
assume that me ans minimized.
9 Now an FMEA is not a particularly great way to 10 discover. common mode failures and therefore, what is--this 11 is, as a practical matter saying that you do an FMEA and if 12 you don't put in common mode failures, you won't get them (Q,j 13 out, of course and that will be sufficient to comply with 14 the rule, as I see it on the previous slide.
15 MR. NEWBERRY:
This is one place where, I guess, 16 our judgment w131 end up with the arguments opposed to us by 17 the andustry.
1R DR. LEWIS:
You have used that term very often, as j
19 If this is simply a two person contest between you and the I
20 industry and presumably everyone, including even ACRS, is on 21 the same side in that we are trying to, you know, make these 22 plants as safe as is reasonable.
23 So it's not a contest.
We're trying to get at 24 what. the basis--
(N.
25 MR. NEWBERRY:
I use the term " industry," and O
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.1 perhaps that's not the best term.
In this case, it was a 2-specific design proposed at one of the plants, one of the 3
f i rs t CE ' plants tha t we looked at and what they had proposed 4
was s power supply designed from the same instrument buses 5
as the reactor trip system.
I 6
DR. LEW1S:
Why do you specify an FMEA to uncover I
1.
7 common mocie tallures?
8 MR. NEWBERRY: Well, the--
9
- 1R. LEE:
For the power source, we usually use the 30 primary loss of power, you have over voltage or under 13 v o l t.a g e, those three conditions and it is based on those 12 three conditions, how the plant can cope with those type'of
(
I 13 failures.
14 And this is one of the designs that we accepted.
15 They have Class I-E, DSS and AMSAC that provides--the power 36 is provided from 120 vo3t safety bus.
Those bus also a
17 provide power to the reactor trip system and they give us 18 the same,effect--analysis on the power failure and we're 19 sa tisf led wit h their analysis, and we accepted the design.
20 But our preferred design, from the first one, is 21 totally separate.
2?
DR. KERR:
Am I correct, this represents 2 designs 23 that were submitted to the NRC and were considered b
24 appropriate?
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~25 MR. NEWBERRY:
Yes, sir, that is correct.
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Hulbert,.why don't ycu go ahead and describe this?
2 But the answer to your question, Dr. Kerr, is that t
3 15 correct, these are two designs submitted to us that we 4
found acceptable.
5 DR. KERR:
Okay, thank you.
6 MR. LEE:
The next item is the staff's view of the
.7 meaning of " diversity".
8 "The basic premise behind the ATWS rule is to 9
prevent or minimize the common mode failures which 10 simultaneously disable the redundant reactor trip 11
'ci rcui tries. "
'12 Our view is that the reactor trip system is a very N
(,_)
13 reliable system.
The only reason for the ATWS rule was 14 mi tigation system, is to prevent a common mode failure.
15 Go the Whole emphasis on the ATWS Rule is the 16 diversity.
And, our interpretation is that the diversity 17 requirement by the ATWS Rule is a hardware of component 18 diversity and the method to achieve these, either by 19 component from different manufacturers or the function of
, 20 capabil i ti es.
23 The function of capability could be the digital
)
22 system versus analog system or AC power source versus DC and 23 energize the energize status.
24 DR. KERR:
Does that then mean the same thing as 25 functional diversity or when you say functional capabili t'y l
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'l because that seems to be different froar what I was hearing 2
earlier in which case, the functional d2versity was not 3
considered acceptable.
4 MR. MAUCK:
This is Jerry Mauck of the staff.
5 Are you referring to the ATTU card, is that what 6
you ' re ref erri ng t.o ?
7 DR. KERR:
Yes.
8 MR..MAUCK:
Have you seen the ATTU card?
9 DR. KERR:
I can truthfully say that I never heard 10 of an A1TU card before this morni ng.
11.
MR. MAUCK:
Well Dr. Kerr if you take a look at 12 the proposed GE ATTU cards, one in your left hand and one in
.( )
13 your right hand, they will be identical cards.
L 14 DR. KERR:
Well, my question was:
Does functional 15' di versi ty qualif y--I 'm trying to understand what is meant 16 byu f unct.ional capability.
17 MR. MAUCK:
True functional diversity qualifies, 18
- yeo, lo DR. KERR:
True functional diversity, i
20 MR. MAUCK:
And the answer to your next question 21 is going to be: What is true functional diversity.
22 DR. KERR:
I was going to be more specific than 23 that, but that probably was the question I should have l
24 asked.
25 But what you're saying is that. if I use two Heritage Reporting Corporation (202) 628-4888 1'
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identical cards, and have one of them doing one thing, and 2'
one doing another thing and one doing another thing, that is 3.
not diversity.
4 MR. MAUCK:
When you say one is doing one thing 5
and one is doing another thing, you mean'that one is taking 6
a different process signal and working on that process 7
'sagnal?
R DR. KERR:
They're just doing different things.
9 MR. MAUCK:
Doing different things, what do you 10 mean?
I don't understand.
11 DR. KERR:
I don't know what I mean except that 12 they are performing different functions.
One is opening a
',(h
.13 switch, one is closing a switch, for example.
()
'14 MR. MAUCK:
No.
If the cards are, in fact, taking 15 ~
t+x) different process signals and it's not the same process 16 signal over in the trip system and the ATWS system, then 17 that is functional diversity.
1R DR. KERR:
So it would be possible to achieve i
19 partial diversity and that would be acceptable with two 20 identical units?
l 21 MR. MAUCK:
As long as one Unit, the same units in 22 both systems weren't processing the same signal, yes.
But I
-23 think that youll find thet GE is using our level in L
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. pressure for ATWS or actuation and in all cases, the GE l
25 plants that have this diversity problem are using the same
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Jevel--
2 DR. KERR:
So the problem is that they are not 3
Identical but that they are using the same signal?
I 4
MR. MAUCK:
That's a two fold problem.
You 5-Wouldn't have one problem without the other, You cannot 6
have the diversity problem if they are not identical or and 7
'if they are not processing the same' signal, true.
.8 DR. KERR:
Okay.
That's clear to you.
I t isn' t 9
clear to me yet, but let me think about it.
10 MR. MAUCK:
I guess it's more clear to the staff 11 t,han it would have been down in the trenches looking at 12 these things since 1985.
( )
13 DR. KERR:
Well, one can get so far down in the 14 trench that one can't see daylight.
15 MR. MAUCK:
That's'true and I guess We're not 16 trying t.o get that f ar down in the trenches and we don' t believe that we have on this particular issue.
18 MR. LYNCH:
Doctor Kerr, diversity is not a new 19 Phrase in the regulations.
It's there in Appendix A and the 20 classic interpretation of it, since Appendix A has been 21 around, is diversity in principal which, I think, Would 22 cover your approach, in terms of functional diversity.
23 Our concern, as Jerry has, I think, correctly put 24 it, is the t.w o, the identical components and the function l
12 5 are, in this case, both identical.
The same signal, same l
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electronic circuatry, same output.
We believe t.ha t is auct 2
a li ttle bi t too common.
i 3
DR. KERR:
So that any reasonable person would 4
probably-agree With you?
L 5
MR. LYNCH:
Hopefully.
6 MR. LIPINSKI There is one other aspect.
They're 7
ta]hing about energize to achieve function.
Another 8
funct2on is fail safe design such as in a loss of power, 9'
your function takes place, failure of E component, your 10 f unc tion takes place.
11 But if you say you want to close a contact to get
.12 a function, this is contrary to the fail safe design, so now
,(j 13-you're giving up some of your reliability.
14 MR. LEE:
The reactor trip system is fail safe
' l' 5 '
design.
Again, emphasized on ATWS rule is not the 16 reliabili ty.
It deals With some common-mode failure type 17 scenario.
18 19 MR. LIPlNSKI:
If you could quantify your common 20 mode failure and tell ne what it is you're concerned about, 21 generally you can design for it.
Right now you're saying 22 you're going to examine the designs, look for common mode 23 failures and hopefully see none.
24 But you think thelre are some residual common mode J
25 failures that you can't identify and that is why you want
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your diversity.
2 MR. LEE:
Right.
)
3 MR. LIPINSKI:
Having that, when you ask for a 1
'1 4
contset to close, rather than to fail open, you have given 5
up some of your, reliability,'by having gone in that 6
direction of diversity.
7 MR. MAUCK:
Well that contact to cl.ose is just in 8
conjunc tion with the other two arguments.
Also what you're 9
trying to look at on the ATWS-System, is to not have an ATWS 10-Gystem that is' inadvertently putting the rods or causing the 11 resert pump trips to trip so one of the--I think one of the L
12 goalsf is to avoid these spurious trips and a fail safe 7q.
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13 system is more prone to spurious trips.
14
. M R J.
LIPINSKI:
But that is when you start going 15 into mul tiple ' logics where not a single train causes a i
16 functlon to;take place, you have to have combinations of 17 faAlures.
i
~10 MR. MAUCK:
Right. The ATWS Rule doesn't require 19 redundancy and if you have a single train and a single
}
'20 channel that is energized, that is de-energized to actuate, 21 then you're very prone to trips.
f 22 MR. LIPINSKI:
This is the entire question then in 23 terms of the reliability.
If you're going to insist on 24 somethi ng being diverse, hopefully it has equal reliability 25 to what you could have in there in the first place and if it g-k Heritage Reporting Corporation l
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doesn't, then you're giving something up.
Take a close look f
2 at t.ha t reliabili ty.
3 MR.-MAUCK:
It's very hard to quantify reliability 4
on t.hese electrical units.
Tne trip system reliability is i.-
5 qu2te h29h and I guess we anticipate that.the ATWS systems 6
that they are pu tti ng in, at this time, are not quite as 7
high, bu t we f eel that that failure in the reliabjlaty is i
8 more due to the lack of industry's cooperation with the 9
techn2 cal specifications and we believe that our power 10 testing will greatly increase reliability of ATWS, not poing 11 to identical components such as the ATTUs.
12 There are a lot of other components that are
/%
(_)-
13 probably as reliable and I would guess, more reliability 14 than that ATTUs.
I 15 MR. LIPINSKI:
But what you're saying is--I can 16 appreciate the fact that you might go'to a different 17 manufacturer but hopefully you ought to be able to 18 ressurrect the data that goes with the component that you 19 think is good enough to do the job.
That they will select 20 the component not known numerically, but its reliability is.
21 MR. LEE:
But the ATWS System does create a back 22 up from any failure on the reactor trip system.
We have not 23 tried to build an ATWS System as reliable as the reactor 24 trip system.
l.
f 25 MR. LIPINSKI:
I'm talking about the individual LC L
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replacement of sensor for sensor that you're talking about.
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2 MR. MAUCK:
Not sensor--not sensor.
The sensors 3
are the same, t:
1 4
MR. LIPINSKI:
What was the name of t.he device you 5
were'us3ng?
6' MR. MAUCK:
This is a transmitter trip uni t, but
'7 it's the signal conditioning device, is stable.
8' MR. LIPINSKI: But if you're going to replace one 4
with another, you.ought to know what the date is on the 10 first. one and what t.he date is on the second one in order to
' nake aEjudgment on the acceptability of the replacement.
- 11 i
l-12 MR..MAUCK:
Well, we don't even do that when we
- /y.
-(_)
L13 look at the trip' system for a plant that is coming through 14' the }icensing stage.
15 We don't get down, as you say.
If we did that, we 16 wou'Ld be way down in the trenches and we would never see 17 daylight.
18 If you expect the staff to get down into component l
19-level reliability for each piece of instrumentation that 20 they have got that is safety related in a power plant, we l
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'21 would never get a plant license.
22 I think that we have to assume that i ndu s t.ry knows L'
23 that tihere is a reliability goal and that they are out there l
124 purchasing things that have the required reliability.
3-4 25-DR. KERR:
Let's assume that industry does know l N-L Heritage Reporting Corporation (202) 628-4888
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1 that..Apparently you have concluded that this particular 2
segment'of industry that is proposing this doesn't know that 3
or they wouldn't be proposing--
4 MR. MAUCK:
No, no.
GE has proposed a reliab3e--
5 as reliable as a trip system, by using the ATTUs because 6
it's he same device, but what they haven't proposed is 7
something to prevent the common mode failure and their 8
Justification was that this switch that changed the final 9'
output relay on the ATTU card and I think that is the only 10 difference is that the relay and the trip system is 11 energized and the final relay which is, I would guess, about 12 two percent of all the components on the card is the only
. /D
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13 different component that is in a different state and'that 14 judge-doesn't' cut it.
15 DR. LEWIS:
Doesn't out it in what sense?
1 16 MR. MAUCK:
That doesn't meet out diversity, 17 havi ng one component on the whole card in a different state.
18 DR. LEWIS:
It doesn't meet it in terms of the 19 straight reading, not in terms--in terms of reliability or 20 in Lerms of straight reading?
21 MR. MAUCK:
No, not reliability. We're not
{
22 discussing reliability.
23-DR. LEWIS:
Just the straight, the straight I
24 meaninge-25 MR. MAUCK:
It doesn't meet--that was their
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i nt erpre tation of beli9 able to have diverse ATTUs, that one 2
component on this card that has hundreds of components on Il 3
15 Ifi a different state.
4 DR..KERR:
Would 2 be enough?
5 MR. MAUCK:
No.
6 DR. KERR:
Three?
7 MR. MAUCK:
Well, you have to look at how many S
components are on the card.
9
.DR.
KERR:
That's what I'm looking at and you told 10 me there were about a 100 components and I'm trying t.o find 11 out how many would have to be different in order that it 12 Woulo be diverse.
L,(,)
13 MR. MAUCK:
Well, not all the components on the 14 card have any state definition with them.
There are a lot 15 of passive components on the card and so you wouldn't expect 16 pass.jve components to be in a different state.
17 DR. KERR:
So your answer is, I don't know?
18 MR. MAUCK:
My answer is I would expect all active 19 components on the card to be in a different state.
j L
20 MR. LIPINSKI:
I would venture to say that if you 21 take that same card, and the first one is one that is really 22 energized and failure of the relay causes action from the L
23 card, when you go to the reverse state and you have a relay 24 that is de-energized and do a reliability analysis on both 25 cards, you wil) fand that your second diverse card has less
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reliability ihan t.he first card, which relay is normally
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energized,.in terms of being fail safe.
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3 MR. M4UCK:
True.
L 4
MR. LIPINSKI:
And since~you're diversity, you 5
-have-gone for something thatihas less reliability.
t 6
MR..MAUCK:
But I would argue that that change in
-7' individual component or board reliability is not significant 3
in terms of the overall objective of minimizing the 9
. likelihood of a common mode failure between the reactor' trip i
i 10 system and t.he ARI.
11 DR. KERR:
Is it valid to assume, from what I have 12 heard so far, that the staff is not concerned or does not r^%-
e a
V 13 look'at overall reliability.
14 What you'do look for is a system that will
-15 minimize common mode failure in so far as engineering I
16 Ljudgment-and. practicality is concerned?
i 17 MR. LEE:
Yes.
i 13' MR. MAUCK:
I guess that's true up to a point, but l
19-as I stated previously, to actually get down and find out to 20 the nearest tenth of a percent of hundredth of percent 21 whether some particular black box is 99.9 98 percent 22 reliable.is very dif ficult and I don't know--
23 If you've got a way that the staff can take an 24 applicant's drawing or licensee's drawing and look at his 25 reliability analysis and prove that that is correct in the f-(_/.
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time frame that we're' allowed to work'on t.hese things, we'll 2
be willing to listen.
3 DR. KERR:
I am unreasonable, but I hope I'm not 4
- t. hat unreasonable.
i 5
MR. MAUCK.:
.1 don't think so.
I think i t 's very--
6 DR. KERR:
The point I am tr ring to make is that 7
diversity is receiving a lot'of-emphasis and rightly so, 8
because of the ATWS Rules talks about diversity.
9 MR. MAUCK:
Right.
.10 DR. KERR:
And to some extent you're slaves of the 11 rules that exist.
12 MR. MAUCK:
Trues.
(N
(),
'13 DR. KERR:
But you have said and I agree with you,
'14 L you can't quantify this.
15 MR. MAUCK:
True.
16 DR. KERR:
So you really don't know how much you 17 are adding to the reliability by insisting on diversity.
18 lt may be a very small quantum or it may be 19 something very large.
You are forced, I think, to be very l
20 quanti t.ative about something--quantitative in the sense you 21 insist on it, which you can't quantity.
22 And therefore, you don't really know whether you
?3 are adding to existing reliability very much or not. or as l-24 Mr. Lewis suggested, maybe you're making it less.
And, it
,~q 25 is tha t part of the process about which I have some concern.
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2 agree, but' i t does seem to me that we all have an obilgation
- 3
-Lo t.r y. Lo determine, as best we can, even it the rule 4
exists, it is accomplishing the ul timate purpose and the 5
. ultimate purpose of the ATWS Rule certainly wasn't 6-diversit.y, i t' was an increase in the reliabili ty of the trip 7
sys t e in.
8 MR. LYNCH:
I would like to throw somethi ng in, 9
. sir, to help clarify the picture about reliability.
10 Let's go back to safety related camponents.
The 11 staff recognized long ago, when it created Appendix A, that 12 indeed i t could not get down to the nitty gritty of being A:
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13 able to, quantify reliability of individual components or 14 systems of components.
15 As a result it took a basic three pronged approach 16 to try to avoid the problem of not being able to accurately l
17 quantify the components.
The first approach was redundancy, I
1R-single failure, board analysis required.
19 The second thing was physical separation.
The 20 third thi ng was tech spec surveillance.
l 21-Now what we're faced with, as of now, going back I
l-22 to the non safety components which is what ATWS is really b
l 23' composed about, is we don't have, as of this moment in time, 24 tech spec requirements on surveillance.
Theoretically a 25-comrsonent'can be put in a plant and run for 40 years and
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1 never be tested because there's no tech spec requirement on 2
it and it's not safety related.
o 3
It's not quite
- t. rue.
I'm stretching to make a 4'
point.
But what we're saying is the staff has never been 5
given the task nor has it assumed the task of trying to 6.
quanti f y reliability on components or systems.
7.
DR. LEWIS:
Can 1 Just interject two things, 11 I S'
may.
9 One is that I think we have to start with the i
10 presump tion that everyone is on the same side in trying to il assure.the reliability of the SCRAM system.
What Bill saic 12-is absolute)y right, the issue was not, at the beginning,
[T j
(_)
J13 not the Ways to do it, but the assurance itself and the way 14 common mode failures became important was that when one did 1S
- t. he standard probabalistic risk assessments of the SCRAM 16' system, the likelihood of failure turned out to be very i7 smali because there really was so much redundancy built into 18 the system and whenever tha t happens then the primary threat 19 does become common mode failures and most of them are not 20 predictable.
There are plenty of antidotes that tell us 21 that they happen even though we don't foresee them, i
22 So I have no problem wi tn a concern about common 23 mode failures.
24 The problem I have is with the sort of knee jerk
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a set of rules which, as we have learned this morning are 2
very amb29uous and depend very much on conflicts in judgment 3
between he staff and the vendors and the owners and what 4
have you.
5 And whenever one has rules which cannot be stated 6
clearly and I think it really has come through that these 7
rules are not state'd clearly now because they come to you 8
and you have Judgments which are different.
9 Whenever that happens, it's very similar to having
.10 laws which are fuzzy and then it's up to the policemen to 11 decide whether you broke the law or not.
12 We have speed limits just to avoid that because
(/
13
.the real law on speed limits is that you shouldn't drive-14 carelessly ore recklessly but it turns you that you can't 15 leave t.ha t to the judgment of the policeman and therefore, 16 we have a speed limit and even at that, we have such slop.
17 When we depend on the comparison of judgment
$. 8 between the staff and the vendors and industry, we're 19 depending very heavily, and I got to say it, on the fact i
20 that you're better sngineers than they are, unless you 01 believe that they're not interested in the reliability of 2?
the system and I don't believe you're prepared to say that 23 in public.
I do n ' t.
think you're even willing to say it in 24 private.
25 And therefore, we are depending a great deal on b('
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1 your being bett.er than they are.
Why should I' depend on 2
that?
Don't answer that, question.
- 3 MR. LEE:
Well this--
4 DR, KERR:
I hope you find this discussion 5
i n ter es t.i ng,
Mr.. Lee.
(,
MR. LEE:
This pret.ty much concludes my portion.of 7 ~-
the pr esen t.a t.i on.
p
'8 The det. ailed stat.us is shown i n the handout.
The
-4 next i tem u exemption request process and it will be 10
. addressed by Mr. Lynch.
11 MR. NEWBERRY:
While Hulbert is there and before 12.
We get into the exemption discussion which Mr. Lynch is Ah.
13 prepared to di'scuss.
14 As Hulbert said, there is an attachment to your
.15 view graphs, I believe, which lists our understanding of 16 where each plant is wi th respecc to their implementation.
17 You can see the system abbreviations for each.part of the 18 ATW3 Rule heading each column and'a date or a yes which 19-describes our understanding of when he would implement that 20 part of the system or has already implemented it.
21 Co we would be happy to respond to any questions 22 you have on those tables.
23 DR. KERR:
I appreciate the tables and I don't
,24 have any ques ti or>s a t this point, but if questions do come
.g 25 up, we can get
- t. hem I am sure.
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But thank you for providing those.
2 MR. LYNCH:
I'm an engineer, so I hope I don't
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sound like an attorney as I star ^ down this path because 1 1
4 dan't have a license to practice law.
5 But with respect to the exemption process, there 6
arc a number of avenues that industry can go and Dr. Lewis 7
is quite correct, when the staff takes a position, it is the 8-staff's position and not tru th handed down f rom on high.
9
~ Ano as a result, it is subject to an appeal process.
10 The basic process of appeal is administrative and 11 legal in nature.
I am going to just describe the 12 administrative procedure.
j (jj 13
.Any utility has the right to come in through our 14 administrative formal process and go through an appeal 15 process, basically at the-branch chief level, the AD level,
. lo the divisior, director level, the office director level, as 17 high as they wish to go pursuing that.
And, it is a fairly l
18 formal process..
We do have procedures governing it and it 19 sc.n't very legal in nature so much as it gives the industry to appealing the--the licensee appealing a particular staff i
21 posi tion, an opportunity to assure itself that each level of 22 management in the chain of command has had a chance to hear 23 their best case, i'
I 24 This process has been used on many o.ther issues
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25 and i t has cut both ways.
Sometimes the licensee has
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2 but we are'not arbitrary, at the working leve] reviewer or 5
3 branch chief may take a posi tion and that is the end of i t.
N-4 That administrative process does exist and has been used b
5 quite 1requently by industry.
6 There is another formal process which is more r
7
- 1. e ga l i s t i c in nature and that is 10 CFR 50.12, allows the L
8 licensee to basica))y request that exemption provided they 9
meet one of 6 individual criteria and without reading the'
-10 whole section-50.12 and, without reading the whole section 11
. o f. 50 12, one of the issues there would be financial 12.
hardship.
/3
(_)
13 Another criteria that could be met and would 14 sa tisf y. the requirement f or the exemption would be that the 15-licensee approach meets the intent of a rule.
36 This process was used by Louisiana Power, it's 17 Waterford unit, at Arkansas and at San Onofre 2 and 3.
We I
38 did consider t.hi s, both internal review.
We did consider 19 t.his at meetings.
We did send out, as I said earlier, 20 letters denying those exemptions, detailing our reasons why.
L 21' For example, on the BWR, those are CE plans.
On 22 the SWRs, as recently as last January, we had a meeting with l
L 23 the owners group, where we thrashed out thoroughly the L
L 24 question of reasonable and practical.
Industry did take the 25 position that the rule itself did include an exemption
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pr ocess wi thin the rule by quoting the words in the 2
statement of consideration or issue With the rule, namely
-3 t.he concept that diversity is required to the extent 4
reasonable and practical.
5 To help put your minds at ease, that I'm not an attorney, we would first look at reasonable and practical 6
7 from the point of view of technical f easibility and what we 8
are really talking about is a relatively low level of 9
technology.
We're talking about circuit breakers. We're-
.10 talking about wires.
11 1 t.hink'a very bright junior high school student 12 could design such a system, assemble it and test it, so
.(/
13 we're not talking about what the staff is looking for is 14 something that.is pushing the limit of technology, we're 15
- really talking about very basic wiring logic and hard wire 16 logic.
So we have always addressed it f rom that particular 17 point of view.
-18 Just as a footnote, if it was not technically l
19 feasible, the dollars involved would sky rocket.
If it is 20 tec.hnically f easible and is the low level of technology that 21 I am talking about, the cross would be relatively minimal.
22 Now, on a personal level, if somebody were to tell 23-me a $100,000, if I am pay for it myself, that's a large 24 dollar amount, but if I am looking at a $4 billion power 25 plant and I am advertising tha t cost over a 40 year life
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t.i m e, 1 would 1, ave to say, from an accountant's point of 1:
2 view, that's not very much.
3 Basically, the staff stands ready, 50 as not to 3
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4 have the reviewers at t.he branch chief level or at the AD 5
level.or the d2 Vision director level view--be the last word 6
on it.
7 We always st.and ready, by law, to entertain any 8
exemption request per 50.12.
9 I don't know if that is the level of detail you n
K 10 wanted, but that's a compromise between a 2 second and a 5 11 hour1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> presentation.
12 DR. KERR:
Mr. Lewis.
l-f i_)
13 DR. LEWIS:
If I might just say a couple of words.
14 One is that somehow the appear process doesn't s
15 give me a-great. deal of comfort because it's an l
16 administrative appeal process and normally when there are i
17 t.e c h ni ca l conflicts and we are talking about technical L
38 conflicts herc, I would like to see them appeal to better 19 and better and more competent engineers rather than higher 20 and higher level people within the system.
21 Unfortunately I recognize that in the nuclear 22' safety business.
In the end you end up in the courts which
-23 are singularly incapable of judging these technical 24 questions, so I would rather not see them appealed up the jz 25 line, but resolved at the best possible technical leve),
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'1' whatever that is.
2 The second point I would like to just say is that, 3
whereas the implementation of these issues may be at a' low 4
tech-level, involving wires, relays and so forth, the issues 5
of reliability of very complex systems are far from 6
simplistic.
They challenge the. hardest part of reliability
'l 7
analysis and ue have been harping all morning on the issues I
4 8
of reliability analysis and I don *L agree at all that those 9
are trivial, when you deal with these questions.
Even if i
10
-the implementa tion may be in terms of relays and wires.
Il MR. LYNCH:
I fully agree with you, sir, and as I 12 mentioned earlier, just a few moments ago, the staff has
/~s
(_)
13' great dif ficul ty with reliability and I would call to your 14 attention'with the' concept of PRA was first brought before l
15 the ACRS, the ACRS did indicate, as I recall, that it was an l
16 interesting concept, but they were concerned that with the 17 limited number of plants, that there was an insufficient s
18 data base to have a fairly reliable set of statistics to
.19 plug into a fault free analysis process and I think we have l
20 not, as a s taf f, yet been able to solve that problem.
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8 21 DR. LEWIS:
Well, you know, all I can say is that 22 I wasn't on ACRS at that tim 9, but I will agree with you i
l 23 that ACRS did not understand PRA very well.
24 DR. KERR:
However, there is a difference between 1
25 PRA and reliability of fairly simply, wel] understood l N)q Heritage Reporting Corporation (202) 628-4888 1
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c :a..ponents wi th whi ch there is a lot of experience, and I 2
don't think that even the ACRS had difficulty with that 3
particular part of the total PRA process.
And, indeed, 4
one of the problems with the reactor trip system, as you 5
recognize after all thete years, somewhat better than I, 6
probably is that we are requiring that it be extremely 7
reliable, more so than any other component or system in a 8
power plant, so far as I can determine.
9 And, it's for this reason that I keep harping on 10 ra) 2 abili ty rather than diversity or redundancy or whatever.
11 What we.are trying to achieve in this system is reliability 12
'and it is such an important system that it behooves those of
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.13 us, not.in the trenches'and those of us in the trenches, to 14_
use whatever tools are available, insofar as we can, to try 15 to achieve that.
16 MR. NEWBERRY:I'think we certainly agree with that 17 objective.
After going through our part of the agenda here, 1
18 I would make just'one observation.
19' Most of our discussion was focusing on the places 20 where we have disagreed with proposed designs from the 21 dif f erent utilities.
We didn't say too much about where 22 plants that proposed acceptable designs have implemented 23 acceptable designs and I would only say that I think all of 24 our objectives are to improve the reliability of the SCRAM 25 function and improve safety at all the nuclear power plants.
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1 I think that the systems that have been installed 1
2
'and will be inst.alled would do that. I would hope, as the l
I#
'3 owners groups go through their part of the agenda, you would 4
get a broader picture of the progress that has been made and 5
should be made and continue to be made in the next couple of 6
years.
7 The ATTU issue, the issue of insufficient l'
8 diversity in a few CE plants are really, as I said, the two 9-remaini ng issues--there has been a lot of work done by the 30 industry.
Where we have looked at it, it's been good work 11 and we have accepted i t and are proceeding with E
12 i mp l eme n ta t.i o n.
.f 5./
13 So,-I don't know that it's a fair picture of the 14 overall ATWG implementation project to just use those two 15 open issues as an example of where we are.
.16 MR. LYNCH:
I would like to address your last 17 comment,-sir, and specifically Mr. Lipinski has raised this 18 point also, as Dr. Lewis has.
- 19 We don't disagree with you, that reliability is an 20 important factor.
And to show you where I stand, if j
4 21 industry were to come in and make the point that there was a
- 22 significant degradation in reliabili ty to go to a diverse 23 component we would,
'sf necessity, be forced to accept their 24 posi ta on almost instantaneously, but nobody has made such a 25 case that if a different component, as diverse component is r.
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utec, w h e t.h e r from the same vender or a different vender, l
?
that there is any quantifiable reduction i n reliabili ty, 3
Since that argument has not been made, we're not 4
free then to say that requiring diversity in component.s is t
5 reduction an reliability.
6 If, indeed, industry can come in and make that 7'
case, very succinctly, we would immediately, I think, agree 8
with them.
I can't speak for the whole staff, but if they 9
were to say t.ha t is the most reliable unit and there is a 10 f a c t.o r of 2 or a factor of 10 reduction in reliability going 11 f.o a different component, the staff would give that great 12 Weight in this decision making process.
13 But that--I am emphasizing for the third time, 14 l.ha t posi tion, tha t.. presenta ti on, has not been made by 15 andustry.
16 DR. KERR:
Thank you, Mr. Lynch.
Anything else on 17 t.his subject?
18 I assume that We covered the detailed status on 14 selected plants with the chart to which you referred us?
20 MR. NEWBERRY:
Yes, sir.
21 DR. KERR:
I'm not sure how that last item--how l
22 did t.h e 3ast item on the agenda?
Did I suggest it be put I
23 there and then f orget it?
Well we thought that--
25 DR. KERR:
This Was regarding some resert pump (N.
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trip failures.?
Maybe you should just tell us about it, if 2
you can, wi thout an exhaustive analysis.
3 MR. NEWBERRY:
There is certainly one recent one 4
of i nterest to us.
Some.of the boiling water reactors use a 5
trip design that opens the fuel breaker to the MG set for 6
the recirculation pumps.
There was an event that occurred 7
a t F e r mi,, a few months ago, where a breaker failed to open 8
whesn i t should have and investigation led to what I believe 9
was the route cause of inadequate maintenance of that 10 breaker.
,i
-11 There had been problems with that type of breaker 12 over the past f ew years, but reviewing the record, the
?N/
13 plants that-have been maintaining'them seem to not be having 14 problems since the service information letters and other 15 maintenance information were provided by the vender to those 16 plants.
17 So, as a resul t of that e' vent, we have a few other 18 activities on going, I believe, there still may be a better 19 way, a more reliable way to trio the resert pumps.
20-As some plants have, there is an in line breaker 21 going to the MG set that appears to be doing a better Job. I 22 have talked to the GE owners group about looking at what it 23 would take to modify plants along those lines, to change the 24 design and also there is a recent memo that I saw where the 25 staff has proposed this as a potentially new generic issue 7gb Heritage Reporting Corporation (202) 628-4888 4
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to flook at the reliab211ty of resert pump trips, so it's 2
. going to be an ongoing issue.
'3
'DR.
KERR:
Was there some reason why the 4.
' maintenance eon the unit al Fermi was not correct or maybe 5
they didn't know that the breaker was there.
6 MR. NEWDERRY:
I believe there was a programmatic ~
7
. breakdown 'i n taking the information that came to the plant, O
the correct maintenance information, such that i t did not 4
9 make is way into the plant procedure.
4 10 DR. KERR:
Okay, thank you.
11 MR. LYNCH:
If there are no further questions on 12-this. issue of ATWS, we would then move on to the next agenda k_
13
. item.
14 DR. KERR:
Okay, let's do i t.
15 MR. LYNCH:
Okay.
That falls into the bailiwick I c>
of the Reactor Systems Branch and we have Wayne Hodges here 17 who'is branch chief and we have two individuals who will be 18 making the presentation.
As I mentioned earlier, Dan Fieno l
19 and Howie Richings and I am now going to turn the microphone 20 to them.
I 21 DR. KERR:
Thank you, Mr. Lynch.
22 MR. RICHINGS:
I am Howard Richings, the Reactor 23 Systems Branch.
I am going to discuss the inner actions of 24 BWR and some hydraulic stability oscillations with the ATWS.
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.occillat2ons
- t. hat. has basically divided off into areas, one 2
dealing with asymmetric oscillations.
First mode harmonic 3
primarily in which the oscillations occur across the core, 4
but in which the average power of the reactor doesn't change 5
very much.
6 4 good deal of the effort on the part ui owners 7-groups calculations and st.aff consul t.a nt. ca i t.u.i a Li ons has 8
been devot.ed to this area, but 1
.4 m not going to discuss 9
t,hi s areas since it iso 1 evidently directly relevant to 10 ATWS, but only tha 1.econd area in which there are symmetric il os illations in which, at least, in the course of the 32 ou 111ations the power does change significantly over the
.j 13 entire reactor and those become the areas of interest.
14 The basic question is will the oscillations in 35 and of t.hemselves or via some other process, inter action 16 process, increase the average power of the reactor so that,
~
17 in t.he course of those events in which energy is being 18 dumped into the suppression pool, that the average power 19 will increase that suppression, pool temperature beyond 20 limits which are deemed desirable for the prevent.
21 The events, of course, are primarily those 22 isolation events in which this suppression pool action 23 occurs.
24 The other associated problem 15, will these large r-25 osc213ations affect what the operator does or what the L'
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system does in some way which will also accomplish the same L
2 undesirable affects, average power, increrte in the reac toi,
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'3 increased temperatu.re in the suppression pool.
4 There has been a good deal.of eftort by the BWR 5-owners group in this area with thus far calculations 6
primarily b'y GE al though EP :I is now beginning t.o get into l
7 the calc 8ulational area also.
8 BUL in the area of the large symmetric 9
' oscillations, GE has maintained, from the beginning, that 10
- f. hey did not believe that large oscillations in and of 11 lthemceives Wsuld increase the average power, that as long as 12 the primary system parameters like inlet flow and so on
.f\\s 13 remai ned as they should be in the system, that they would 14 not. affect the power.
15 They have done, with their TRAC code and its three
.36 dimensional calculations, a calculation of large 17 oscillations and it is their contention, from this J8 calculatlan, in part2cular, that they have demonstrated that 19 there is no significant power increase at any variation 20 seen in the course of these calculations or residual system 21 effects occurring as affects of changes in the initial 22 condi tions.
23 DR. KERR:
Is there any reason to believe that 24 1RACT 1s capable of handling this problem?
I guess there is L-25 or GC wouldn't be using it, but certainly i t wasn' t
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' 1' reawonably intended to handle this problem necessarily.
2 MR. RICHINGS:
They are doing benchmark
~
calculations, at least the LaCalle event, to see that it can 4
produce as a type'of results that were seem in LaSalle and 5
perhaps others.
6' We have not, as yet, seen their complete program.
r 7
We are still awai ti ng their report on this subject, so we 8
haven't done'an official review in this area.
But they have p
.9 and or will do bench mark calculations, as is going to be 10 true throughout the calculational program, both of our 11 consultants and of GE and EPRI.
L 12 As of this point, the. general consensus appears to (q
_/
13 be, yes, it's perfectly capable of handling this type of 14 problem.
That includes our consultants too from, for 15 instance from INEL, which you is also going to be using TRAC 16 in this area.
17 So, as far as we know, at the moment, there is no 10 reason to doubt that it can handle this reasonably well.
19 MR. HODGES:
Is the major obstacle to using TRAC 20 for a problem like this, is the pocketbook. It's a very 23 expensive analysis.
22 DR. KERR:
And this is also a problem that is not 23 well analyzed as TRAC and other codes have been demonstrated 24 tio work well if one has sufficient data so that they can be 1-.
25 tuned to deal with the problem, as you know better than I
\\_/
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1 and I' guess I would--go ahead.
2 MR. RICHINGS:
Our ultimate, of course, decision 3
W111 be based, not only on TRAC, but on our consultant's 4
codes and a number of calculational areas, all of which will S
De bench marked as much as possible with experimental) or observed da ta f rom plants and there have been a number of o
7 cases in which there have been relevant oscillations of 8
reasonably large magni tude, at least up to a 100 percent 9
type power oscillations.
10 There has been, thus far, peer review of the GE
'l l calculations by EPRI. We have had several meetings with GE l.
12 in which these calculations have been discussed, but as I 3 l 13 say, we have not yet received the first report on the
%s 14 subject., which is due about now.
It was due sometime in 15 April, so we expect to see i t almost anytime now.
16 Bu t GE, at least, and the owners group and 17 presumably EPRI, since I have heard no adverse comments 18 coming out. of EPRI thus far.
Their basic conclusion is that l
19
'there as no evident problem in this area.
They have not yet l
20 explored the subject of oscillation inner actions with'the 21-system and with the operators.
This is now being done by p
22 EPRI.
EPRI recently started in this area.
We have no 23-results from them yet in this area.
24 DR. KERR:
Okay.
Now let me see if I understand 25 your first statement that there are no problem.
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1 implies if.one did not shut the reactor doWn wit.h *he trip 2-
' System, but presumably did get, pump
- t. rip or--
~ 3 MR. RICHINGS:
Yes.
The situation is'.just afLer 4
1.he iniLial isolaLion event, the reactor has gone to part 5'
power becauc.e of t.he pump tr1p.
It is sitting there at some 6.
30 percent power or so and presumably now oscillating, as 7
differing from t,he previous calculations, although'GE did 8
i nclude oscilla t.i on type calcula tions in their previous ATW5 9'
work in t.his area.
The only question is, at that time, they
.l O werfi Introduced someWhat artificially and were they done 11 appropriately at that time, which is why it is being 12-exana ned at this time, p
- d 13' DR. KERR:
Now when they say there would be no 14 problem, t,ha t means that the average power would not be any 15_
grea t.er tha n-16 MR. RICHINGS:
Right, the average power would 17 remain t.he -same and t.he suppression pool increase in 18 t.emperat.ure would be as already approved in the previous 19 ATWC calculations.
20 DR. KERR:
Okay, thank you.
Just try to state a 21 little bit of the basis for why there is even a question.
22 If you t.r y to say from a first principal's view point, well 23'-
I've got a certain amount of feed water going in with a 24 certain amount of sub cooling, and the water level is going 25 address itself to support whatever average power you're V
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putting in there, you can make a'relatively simplistic 2
argument that it shouldn't change,-but the power shape is 3
such that the--it is not symmetric if you pool an average 4
power.
The top half is not the same shape as the bottom 5
half.'of the oscillatory curve and the fact that the LaSalle, 6
although it was thought tha t, i t was due to a decrease on the 7
feed Wat.er temperature, there was an observed increase in 8
power and so those two together, at least, raised a question 9
that needed to be looked at, but from a simplistic 10 s t a ndpo i r,t, you.would not expect to have the power to go 11 out.
12 DR. KERR:
But I don't think this is a simplistic 13 process or.a simplistic argument is 'not going to tell you 14 much about i t.
15 MR. HODGES:
It's not a simplistic process and 16 that's why we're going through all of this.
17 DR. KERR:
I just wanted to say, this is your gut-18 reaction based upon a simple look at it says it should not 19 increase, but the power shape is not symmetrical--the
-20 oscillat. ion is not symmetrical, about an average and 21 therefore, you want to look.
22 MR. RICHINGS:
h of this point, GE and the 23 owner's group have indicate there is no further need to do 24 these large oscillation calculations and we have asked them 25 to do more.
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As of the momcht, this as.on hold until we do, 2-li ndeed, review the written report on the subject and come to 3-
.a more formal decision in t,his area.
1 So there still may be more or there may not be
- 5 more.need f or. f ur t.her large calculations.
6 The EPRI work on inner acti'ons, however, will be
-7.
going on.
8 DR. KERR:
The EPRI work on the inner act. ions--
9 MR. RICHINGS:
On the inner actions of the 10.
operator and the system because of the existence of large 11 oscillations.
12 DR. KERR:
Thank you.
. rN.
Ass!
13 MR. RICHINGS:
Now for our consultants work in 14 this area that'has been going on, B&L has been using RAMONA 15 and the EPA, which is Engineering Plant Analyzer, which is 16 also' called by various other ini tials at various times like 17 HIPA and so on.
I'll call it EPA here.
18 That is incidentally a point kinetics with 19 neutronics in it whereas RAMONA is running full 3-D, very 20 much like the TRAC 2s except in its f orm as its used at 21 Brookhaven, it is much more rapidly operating codes and 22 TRACT and therefore, can be used a little bi t more f reely 23 than TRAC 3-D can.
24 The problem with RAMONA, however, that was
'25 oscillations where the primary interest is one of just.
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.1 loot 2ng at the large oscillations and seeing what they do in 2
and of themselves 2s that RAMONA has numerical problems in 3
thermal. hydraulics, has thus far these problems and it 4
basically breaks down f or doj os these calculations when you 5
get t.o large oscillations.
The primary effect is that it 6
takes. forever to runt he calculations once you begin to see i
'7 t.h i s, particularly when you get to reverse flow with the C
. inlets, the system just breaks down.
9 New thermal hydraulics is being introduced into 10 the system..That's going on now, but that has halted work 11 that has been going on with RAMONA and therefore there is 12 from RAMONA no significant output in this area other than 13 the large calculations which did occur.
They'weren't nearly 14 as large.is we would like to have them, on the order of 100 15 percent oscillation, showed no particular signs outside of
)
16
'the' system affects, once again, of intrinsically causing l' 7 problem areas.
18 But, we have not reach any conclusion in that area 19 yet because of RAMONA.
l 20 The EPA calculations have explored a number of 21-ATWS scenarios. They have begun to get into this area of 22' looking at a number.of-scenarios, seeing what the
?3' oscillations themselves, we haven't gotten into any 24 questions of operator action here, but seeing what the 12 5 system is doing and seeing what the large oscillations are O
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2 There is tendency on the part of those at 3
Grookhaven running the EPA to believe that there are, 4
indeed, power increasing affects from oscillation, but thus 5
far, the calculations which have been one, do not give any
-6 clear sepaiation of effects or any quantification of w' it F'
7 might be going on there.
So we are continuing to explore L
8 the types of calculations which might be necessary to 9
further examine this question.
10 We are right now'in a state therefore in which we 11 have some slight indications that there may be a problem 12 here, but we are no where near yet ready to quantify it and n.
(/
13 say that there is.
14 DR. KERR:
Remind me again, what is EPA 7 15 MR. RICHINGS:
Engineering Plant Analyzer.
ABWR 16 for handling the entire system primarily, with point 17 kinetics in the core, so it can handle symmetric 10 osc i l l a ti o ns, but not asymmetric oscillations.
19 DR. KERR:
Thank you.
20 MR. RICHINGS:
And the last slide. The future 21 plans are, as I said, to improve RAMONA to get the thermal 22
'vyoraulics improved so that those types of calculations can 23 be done. We intend to bench mark RAMONA^against, at least,
'24 LaSalle and hopefully Ostrisham--Ostrisham because it is an 25 asymmetric one and its interest to the other side of the Heritage Reporting Corporation (202) 628-4888
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problemswhich I am no t.' discussi ng.
L 2'
And'then we will go on to a--once thst is 3
accomplished, we will go on to explore these large.
1 oscillaLjons again wit.h RAMONA.
5 The EPA, as I said, further scenarios'are going on 6
- 1. 0 aitempt to quantify what. those calculations or to what 7:
the people doing those calculations believe are indications
'S of a average power increase.
9 Also, we're beginning work with INEL'using. TRAC in 10
'a 1-D mode f or.these calculations. They too will be 11' exami ning scenarios. as a separate code in this area, sort.of 12-as a supplement.to the EPA.
In the 1-D mode, it is, of A
'\\~l 13
'c o u r 2.e, capable of. operating much more quickly.than the 3-D 11 mode so we can do a number of calculations there.
15 TRAC 2 will be bench marked'agairest some of these 16 events and RES has set, up a review team, including h
3' knowledgeable members throughout the NRC staff and through Ad-consultant's areas and we are, in this group, set, ting up an L
19 examination of the whole problem and seeing what 20, calcu3ations should be done, need to be done, what the 21 explanation of - the calculations results are arsd so on.
E
?2 This has been in ef f ect f or about a mcnth now and 23
.will continue on for the next year or so.
The basic l
24 program--calcula tional program in this area is expected to 25 cont 2nue on the order of another year or so before l
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everything is settled.
A good deal of the work, of course, 2
has.to do with the Asymmetric calculations.
All the 3
bulletins we put.out thus far have to do with the asymmetric 4
cal cul a ti ons, not with the ATWS problem.
5 And that is all'I intend to say to day.
6'
.DR.
KERR:
Who is responsible for the RES review 7
te:am O
MR. RICHINGS:
RES is running it.
You mean a name
'9 or what?
'10 DR. KERR:
If there is a name.
'.1 1 MR. RICHINGS:
Harold Scott is the person in
.12
. charge of setting up that review team.
I'm not quite sure--
's 13 DR. KERR:
Dces it have a chairman or is it a 3 or 4 person commi ttee wi th no head, how does it operate?
15 MR. RICHINGS:
The chairman is basically either 16 Dave Vicette or Harcld Scott of RES.
It has about--
o 17 DR. KERR:.They haven't decided which one or you 18 mean it ro tates f rom day to day.
19 MR. RICHINGS:
Well, I'm not really sure.
They're 20 both.there in the meeting and I'm not precisely sure--
21 DR. KERR:
Harold Scott works for Dave Visette and 22 so it probably depends on which one is there.
23 MR. RICHINGS:
And if you would like to know who 24 is on it, I can tell you who is on the committee.
fi 25; DR. KERR:
That's enough.
Any questions or l t I '
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c onnnen t.s f r om any of the subcommi t t.ee ?
2 There being none, t, na n k you.
Mr. Richings.
3 MR, NEWTON:
I'm Roger Newton.
I am Chairman of 1
he Westinghouse Owners Group, also from Wisconsin Electric 5
Power, Point Beach Nuclear Plant.
6 I would like to be opt 3mistic and hope that thjs 7
1s our last. presentation.on ATWO before the ACRS, but I
?
a l w a y :.. get surprised in that area as well, 9
DR. KERR:
Well, you didn't want to feel 10 negjected.
)1 MR. NEWTON:
Right.
12 But, on behalf of the owners group, Dr. Kerr, I
,m I
V 13 1hink we can provide you a gooc update.
In a similar 14 manner, I think we have the statement, similar to what the IL B&W group said, we don't think we have an, issues lo remaining.
That's a brief hist.ory.
You have a slide of 37 t.ha t in the handout.
1G The key items, I think, are when we submitted the 19 generic designs to the NRC in response to the rule, and 20 we'll cover that in a little bit more detail, but quite 21 briefly.
Somewhere in this time period, probably right in 22 this range, plants started submitting their plant specific 23 designs for approval by the NRC.
24 We have 1,wo main products
- t. hat address ATWS, the
/^s 25 generic AMSAC design and a more recent one, that is a b
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2 coefficient, we i nterpret that rea))y to be how do we 3;
address the rule.
So those are the two main products which-4 we will cover in a little bit more detail.
5 The Owners. Group ATWS Rule Programs have a couple 6
of goals'.
The main one is to provide a generic means of L'
7 addressing the ATWG Rule and that was to benefit the 8
u tili ties and to benefit the NRC in their review process and 9
Lo provide uniformity in addressing it.
10 We also were looking for flexib21ity in how to
'11 address the rule, but this is more in now we can implement 12
.i t that best allows the plants to pick different systems A/
13 for the AMSAC design.
34 Again the two main products are the W Cap that
-15 addresses the generic design with a rev to it and the W Cap 16 that addresses the ATWS Rule basis.
So those are the two 17 main products.
18-A couple of comments
- t. hat I would like to make 19 that we didn't have slides for, was the question of 20 reliability that was asked previously.
21 There are really two forms of reliability, just 22 listening to the discussion that took place.
One form of I
23 reliability is reliability of the system to function when 21 needed to' function and the second one is the reliability of 25 the system not to function when needed not to function and r.
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both of those reliabilltles are important.
2:
The NRC tends to be more concerned about the first 3
reliability and I think the industry, outside of the NRC and 4
the utilities, are concerned abouL both of them and just as
.5 important the not to function when not needed because that
-6 means our plants will stay up and we won't challenge other 7
systems.
(
8 The comment was also made by the NRC that we have 9
not. made reliability arguments to the NRC an I think we
~
in that when we approach some of the designs--generic 10'
- have, 11 design aspects,.we specifically did look at reliability and i
12 the NRC recognized that.
13 An example of that is that for the AMSAC design, 14 it is not a system that will actuate when you lose power.
15 I t 's an active system, so that if you do lose power to it, 16 11: Will not trip the plant off line.
So it is not adding to 17 the unreliability of the plant in that regard.
And that was 10 a reliability issue that we showed that reliability was 19 Important.
20 DR. KERR:
And when you presented that issue, you
{..
21 received sympathy and understanding?
'22 MR. NEWTON:
Excuse me.
I was looking at the next
'23 slide.
24 DR. KERR:
When you mada that presentation, you 25 received sympathy and understanding?
.O f
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MR. NEWTON:
Yes.
And they accept it, so we must
~ 2' have,'right.
3 The next area that we will be getting into and' 4
Melita'Osborne, the Manager of Transient Analysis will cover 5
the. specifics of the two areas that. the. owners group has had 6
proqrams-in.
7 MS. OSBORNE:
What I would like to do is address 8
the'two main owners group programs that we did to address-C' ATWS; AMSAC, the'ATWS Rule and what not.
10
-The first one is the development of the.AMSAC 11 f unc tional design which, as Mr. Newton mentioned already, 12 has been approved by the NRC.
O N/
13.
.This was a joint effort between. Westinghouse and 1 -1 the utili ties and the goal was to allow utilities to select 15 a design.that would be best suited for them when it actually 16 came time to implement it.
17 The utili ties actually met with Westinghouse in JS our offices in Pittsburgh and hammered out three different 19 designs which are at the bottom and each one of these 20
. designs meets the requirements of the rule and they have 21 been approved by the NRC.
3!2 Basically they are all indicative of a loss of 23-heat sync.
You can choose any one of the three designs, but 24 the NRC in their SER on the generic topical report, also 25 st.ated that the plant specific aspects would have to be gg Q:
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'l ievicWed separately.
A lot of the issues associated With 2
impJesienLation are really more plant specific t.han can be.
3 addressed WOG topical.
4 So, as I already mentioned, the generic part has 5-t>een approved.
There were two key e]ements addressed--
G identified by the staff which the WOG addressed generically.
j r
7 One of.them'had to do With the power levels below Which O
AMSAC is noL~ required and the other one was a question 9'
W he t.he r or not tech specs were required.
.10 The other elements were required for the utilities 13' to address in their individual submittals.
12 I would.like to shift gears now,lfor a moment, and 7,
\\.
13 talk about the second program that--
14 DR. KERR:
Excuse me.
What was the decision on l-35 t he: tech specs?
It MS. OSBORNE: That's still open.
17 DR. KERR:
Okay.
That is not regarded as a 18 serious issue since we earlier heard that no serious issues
.1 9 still existed?
20 MS. OSBORNE:
It's not an issue that is serious in 21 t.erms of implementation.
Tech specs themselves, are not 22 pieces of hardware.
23 DR. KERR:
Okay.
24 MS. OSBORNE:
No one would say that they want more f-'
25 tech spect, however.
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Switching gears now to the second program which
'2 the owners group worked on wi th Westinghouse.
As Dan Fieno 3
mentioned earlier this morning, the NRC issued 4 letter to 4
al'1 the owners groups asking abou t the effecLc of changes in 5
fuel management style.
6 And the purpose of this program was to answer t.ha t
-7 question,. bu t also to answer it in the context of all the
.8 integrative affects of an ATWS because-MTC is not the only 9
t,h i ng that can affect a plant response to an ATWS event.
10 It's the total core and it's the total plant configuration.
11 What this program did was to review the basis of 12 the ATWS rule and history leading up to it and I won't go 13 into all of t.h a t, you know it.
b 14 Most of the basis for the rule is contained in 15 CECY 83-293 and there was a PRA model in that document that l
16 was used to come up with the conclusions that AMSAC was
'1 7 required.
And we used that as a basis to construct our own i
18 event tree.
f 19 It was consistent with the rule basis. We were l
20 still trying to meet the target of 10 -5 that was in SECY 21 83-293.
We still treated all the ATWS events as loss of 22 heat sync events. It was a little bit more specific to 23 Westinghouse PWRs and it did include the fact that AMSAC 24 would be installed.
s(
25 At the time the IPE letter had not bee issued but i
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accident. policy statement so
- t. hat when the IPE letter was 3
issued-t.he ut.11ities could'take this ATWS portion of it and 4~
Lhen integrate it into their IPE.
5 Our conclusions and this topical report was given 6
to the NRC for information a month ago showed that we are
.7 still meeting the target. of 1 x 10 ~5 and that is presented 8
in-terms of a core damage frequency for the Westinghouse 9
plants.
'10i DR. KERR:
That core damage is defined as?
11 MS. OSGORNE:
Well, in this case, core damage was 12 actua33y equated with public risk and that is not normally N
- (d' 33 t,he case.
It was conservatively assumed that--
14 DR. KERR:
I didn't. ask my question very well.
15 There is a spectrum of definitions of core damage from water 16
'10 inches below the top of t.he cere to the core on t.he floor 17 and'I am wondering which of t.hese or maybe none of them.
1 L
18' MS. OSBORNE:
Well, for a detailed definit. ion, 1 19 will ask Mike Hitchler to give that.
20 MR. HITCHLER:
For the purpose of this analysis, 21 we assume exceeding stress level C conditions was the l
'22
. equivalent of leading to severe core damage.
l 23 DR. KERR:
Okay.
24 MS. OSBORNE:
That was also what SECY 83-293 L:
25 assumed.
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DR. KERR:
Thank you.
2 MC. OSBORNE:
A couple of other conclusions in our I
is required to meet the 3
NR.W-11993 is that.although AMSAC 4
target, it's unavailability is not of significance in 5
contribu ting to the core damage frequency and that is 6
because there is really no one factor that affects risk and 7'
there Were other things as wel).
8 The MPC, obviously is one that the NRC questioned 9
us abou t and got review of this program, the eligibili ty of i
10 pressure' release, the number of ini tiating events that you 11
-have, obviously affect the core damage frequency.
12 The fuel management question, specifically that jn
(-
.13 t he ' s taf. f asked, had a small to insignificant affect on the 14 core damage frequency and that was really depending upon l
l 1
t 15-Whether you had adequate pressure release capability or not, j
-16 Not so much whether or not it was an 18 month cycle or a 24 l
l-l 17 month cycle or a 12 month cycle, but whether or not your l
j 18 PORVs were gagged.
l 19 And finally, now that the IPE letter has been I
20 issued, we can say it is compatible with--
l l
i 21 DR. KERR:
Excuse me.
Maybe you could back to the j
22 10
-5.
Is this 10 -5 the contribution to core damage due to 23
~ ATWS or.contribu tion due to all causes?
I L
24 MS. OSBORNE:
- Mike, a
l 1
g -
25 MR. HITCHLER:
Yes.
The 10 -5 is strictly due to l
i I
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2 DR. KERR:
Okay.
And this is In the context of 3
generic analysis or analysis of some class of plants or--
4 MR. HITCHLER:
Well the analysis is very i
5 Westinghouse specifio in terms of standard design practices 6
for core relcads and we chose abounding set of condi ti ons,
7 in terms of numbers of steam generators, transients, also a 8
very important part of the W caps, the middle, was a large 9
number of sensi tivity studies, and we thought there.ey be 10 some varuttions, that we didn't want to unnecessarily 11 penalize the entire Westinghouse class of plants with.
12 And so i t is a bounding analysis and it has also O-
\\~
13 taken into account what I would call outlyers.
14 DR. KERR:
I'm trying to understand what is being t
15
. con tr i bu ted to.
Is this in the context of a total core 16 damage frequency of something.
This is 10 -5 contribu ting 17 to 10
-4, 10
-3 or--
IR MR. HITCHLER:
It could t>e 10 -5 contributions to 19 overall core melt from all events.
20 DR. KERR:
And which would have been how much if L
21 you had anal',-zed the plant for the total?
You didn't do 22 that, you just--
23 MR. HITCHLER:
We didn't do that, no. The view has 24 been tr adi tionally that current generations of plants have a 25 total core melt frequency from all events on the order of
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1 5 x'10 -5 to 10
-4.
We f el t that the targets apportioning ATWG to being less th.in 10 -5 would assure that we wouldn't 3
change any of the overall conclusions or goals that ATWS set
~
~4 for overall core melt risk.
5 DR. KERR:
SoLthe 10 -5 then was an upper limit in 6
your view and not necessarily what the contribution would 7
be?
8 MR. HITCHLER:
Ri gh t.. We feel that that is'an 9
upper ]imit and that is consistent with the basis that was i
10 set f orth in SECY 83.293.
11 DR. KERR:
Thank you.
12 MS. OSBORNE:
In Summary, the owners group has I
,r m k/.
13 done two programs to show that we complied with he ATWS 14 Rule.
We have developed an AMPAC design and then we have l
15 looked at the basis of the ATWS rule to see that we we're 16 s ti l l meeti ng the basis of the ATWS rule as well.
17 I'll turn it back over to Roger Newton Who will 10 now talk about the sta tus of implementation.
19 MR. NEWTON:
In anticipation of the meeting, we 20 sent out a questionnaire to the members of the Westinghouse 21 Owners Group asking them certain questions with respect to 22.
implementation.
23 Within the owners group, we usually do not act at 24 an enf orcement agency with respect to once a product is 25 produced, it is up to the utility to use i t and in many
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cases, t.he NRC to work with the utilj ties on imp l eme n t.i ng 2
t.ha t, consist.ent with the regulatory process.
i 3
So we sent out quest.ionnaires asking how many--we l
4 got. answers back', in a short time from 26 sites, 43 uni ts 5
and we just asked which ones already had NRO approval and 6
for those 2es, 22 had been approved by the NRC, 3 Were j
7 pending and one indicated
- t. hey had not yet submitted a I. specific plan.
Looking at the list that the NRC provided, in C
10-
- t. heir attachment, we seemed to' match up fairly close to j
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11 that. In t.he installation 22 Were installed, 7 were to be 12 installed shortly or at the next refueling, probably during 1
.('
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13
'89 is how that was answered and 14 were yet to be 14 installed.
15 Our actual operating experience with the AMSAC 16 sys tem -is ver y little at this time.
On the average, it's 17 just 4 1.o 6 months, with a range of O t.o.18 months.
In So we don't have a lot of operating experlence IQ wi th AMSAC ye t.
We have had no indications that there have 20 been problems with respect to the design or how it was 21 designed and implemented that are causing problems.
It may 22 be a little to soon to tell.
1 23 I know that f rom my utility standpoi nt, we have l
2 -1 approached the reliability aspect of inadvertent trips at 1
7f 25 the plant very carefully in our design because we had to
'(
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make sure we weren't adding more risk to the plants by 2
causing
- t. rips than we Were trying to protect from the AMSAC 3
part of the system.
4 MR. DAVIS:
Excuse me, Mr. Newton, a question.
5 MR. NEWTON:
Yes.
6 MR. DAVIS:
How often do you test that system?
7 MR. NEWTON:
That was an issue that was asked by 8
the NRC and we had to provide the design to have it 9
testable, so pretty much, all AMSAC designs are testable.
10 In the questionnaire, we asked the utilities what-11 are they planning to do with respect to testing their system 12 and there was a whole range of answers from almost-every
\\~
13 week to every refueling.
So obviously we didn't ask the 14 question completely correct because testing of the plant may 15 be testing the alarms versus testing the system from one end 16 to the other.
17 MR. DAVIS:
Does that mean there are no tech specs 18 for testing the systems?
19 MR. NEWTON:
That's one of the issues that we--and 20 when I come to the end, tech specs is an open item, so I can 21 cover
- t. hat at that time, if you want.
22 MR. DAVIS:
Thank you.
23 MR. LIPINSKI:
Another question.
What about the 24 reporting requirements?
This is not a safety system, so it 25 falls outside the reporting requirements of safety V(~g i
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MR. NEWTON:
That is correct.
3 MR. LIPINSKI:
If you have failures in the system, j
1 will t.he NRC ever know abou t them or will that just be 5
internal?
C.
MR. NEWTON: It woul" be--we're proposing
- t. hat it.
7 would be internal, that it would just go into a reliability i
G.
.Lype data base that is generally available to the industry i
9 and I think to 1.he NRC too, but if we don't have tech specs 10 Lhat call
- t. hat a safety system, which it is not, 1L would 11 probably not be reportable.
i 12 So we would be looking at and we have asked
..g 3,..
13
. target,s on what is the reliability of your system and we l
14
.just haven'L had enough operating experience to answer that.
15 DR. KERR:
You haven' t done any--niade any ef f or t.
16 t.o ana]yze the reliabi1ity of the systems?
17 MR. NEWTON:
The basic design that was propoc.ed 18 and the generic looked at the reliability very carefully 19 from both aspect.s of performing the function and for not 20 performing the function.
So there was redundancy involved 21 In t.he design.
In our particular plant we made sure we had redundancy on redundancy so that, it. functioned 22 kind of a
?3 when it needed to and it didn't function, so we feel that 2 -1
- t. hey are very reliable systems for both of those reasons.
fm 25 DR. KERR:
That's a very quantitative answer.
N Heritage Reporting Corporation (202) 628-4888
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' 'w 81 J-MR. NEWTON:
My next s,'ide will show why that.is 2
difficult to answer.
'3 As.Melita 2ndicated, there are three different i
4 choices of systems tha t can be used and we asked what i
.5 particuJar choice did you make and we found that the steam 6
generator Iow level seemed to be the dominant one.
Low main 7
feed water flow was next and tripping of feedwater pumps and C
valve closure was the third.
.They all were indicators of 9
loss of main f eed wa ter flow.
10 Each.of these systems do have different designs 11
'and how they were specifically implemented at the utility 12 Was pretty much plant specific and the NRC'had to review
.p
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'13 each one of these and approve them.
'14 This also comes up at--since we proposed systems 15 that were generically designed, we could do a number of l e, thi ngs on who we bought them from.
Eleven were bought from 17 Westi nghouse, 5 wer e utili ty design systems and 8 were other 16 suppliers.
17 So there is a lot of different hardware out there 20 that u tilities could implement in a manner they felt best 21 suited their design, their budget of whatever reasons they l
22' wanted to use.
Out the WOG design is generic and the design l
23' targets they met were consistent with what was submitted and 24 it met the reliability goals that were in the owners group
/~%
25 report as well as what the NRC was looking for.
(_)
1 l
Heritage Reporting Corporation (202) 628-4888 1
1($).
22 L-1 And the NRC has been approving these and I am 2
sure, speaki ng f or my own utility, we went through a number 3
of it. ems as t.o the reliability of the power supply and 4
independence and t.hings like t.ha t, that they had asked that 5
we address in our plant specific proposals and we were able 6
fo reach agreement mon all of those and, as indica ted by the 7
status, a large number of utilities are 'also reaching an 8
agreement with the NRC. on exactly how to implement it.
9 How reliable those systems are, in a specific 10 number sense, I don't have a number that we can give you and
~
11 I Lhink it will be a period of time before we can answer 12 that and I am saying reliability from the standpoint of both A
13 aspects.
14 There won't be too many demands on the system to
'15
.cperate, but there will be a lot of demands on it to not 16 operale and to be available to operate, so those are the two 17
. categories of reliability we will be able to keep
- t. rack of l
J 18 in the future.
j' l
19 MR. HITCHLER:
Roger, can I say something quickly?
20 MR. NEWTCN:
Sure.
l L
21 MR. HITCHLER:
In terms of the design, we assessed 22-
- 1. hat we wanted to have a reliability of at least 10 -2 with 23 the kind of goal that we had in terms of specifying 24-configuration.
rm 25 The configurations that. were specified, if you go Heritage Reporting Corporation (202) 628-4888
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to like plants because we haven' t done reliabili ty test for 2
ever y plent, but for the configurations that we have seen, 3
1.hc r e] j abili ty has been between 2 x 10 -3 to 5 x 10 -3.
We 4
have.to get.into specific hardware.
5 So we don *t feel that, in terms of when we go out 6-t.o the individual suppliers of components or whatever, that 7
. we are right up agai nst the wall in terms of having a 9.99' 8
10 -3 reliability in safety design.
9
'4ha t we have also done though is, in terms of 10 sensi t i vi ty, in terms of the design, to meeting t.he ATWS 11
' rules requirements, whereas we looked at the impact in terms
-12
.of changes in the reliability of AMSAC.
In other words, the A
k-13 base line analysis says, we're going to have a reliability 14 or a non reliabili ty of 10 -2 for demand.
15 We look at the sensitivity of what happens if that 16 changes by half an order of magnitude, up to 5 x 10 -2 and 37 we saw a very small' change in terms.
In other words, we're 18' still way below the 10 -5 goal
- t. hat we se t f or ourselves i n 19
. t.etr ms ' of ATWS risk.
20' So we don' t f eel we're sensitive, either from the 21 standpoint of variations in terms of fine detail in the
'22 AMSAC configura tions or i n terms of--even in terms of 23 changes i n 'erms of. testing requirements, whether you have a 24 tech spec for i t or you just use good practice for testing.
25 MR. NEWTON:
We also asked the utilities, are ms Heritage Reporting Corporation (202) 628-4888
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Lhere any open items that kind of still remain with respect 2
to.AMSAC implementation and only two came out.
Tech spect, 3
our generic. one thnt we have been aware of with the NRC, we 4
have submitted a couple of letters identifying why we don't 5
Lhink tech spec on AMOAC is a requirement.
Obviously, 6
somewhere in our administrative controls of the plant, you 7
do have to have some requirement for testing and maintaining i
thal belong in tech specs, we don' t f eel that 8
IL.
BuL does 9
il does-,
10 The second one that has occurred in the control 11 room human factors review.
Generally the NRC was asking how 12 does-this fit into the control room and each utility had to 13 look at that and that may be an open item with the NRC for 14 when they come ou t and inspect, that will be an item they 15 will probably be looking for, as did you put this into the l es.
control room in a place, that form a human factors 17 clandpoint, it fits well into the control room.
18 As an example, in our particular plant, the 19 en gi nee r wanted to call this an AMSAC turbine trip.
We went 20 to the operators.
The operator had no idea what AMSAC was 21 and the more we thought about it, he probably would never 22 know what AMSAC was or meant.
It was a foreign term to the 23 operator.
24 So we went back and sat down with the operators at 25 the plant and said, what is this trip really doing and we g
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had to come up wi th a name that represented what was 2
occurri ng and i t was a loss of feed water, a trip of a turbine and start of off speed water pump.
So we had to 4
nania i t by the functionality of what it did for the 5
operator.
And it is likely that we'll never use the word 6
AMSAC in the plant..
7 That is Just a human factor type thing and what do C
you call--how do you label alarms of by pass and trips, so 9
these are all items that each plant is having to look at.
10 It has not been signed off.
11 In your plant, prior to this installation of this 12 system, what would the opera tors have done-with the off feed
(/
13 water manually or whatever in case of a ATWS, maybe it was 14 automatic before.
15 MR. NEWTON:
They would have--before meaning--
16 DR. KERR:
Before implementation.
17 MR. NEWTON:
Of this.
15 DR. KERR:
Yes.
19 MR. NEWTON:
I would say af ter the new emer gency 20
' response guidelines.
21.
DR. KERR:
Okay.
22 MR. NEWTON:
Because the new emergency response 23 guidelines really address ATWS from an operator response as 24 well and they do a number of things when they obviously--
25 immediately you go to manual trip on the reactor SCRAM
, ~s V
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11' l.ha t, doesn ' t, Wor k, drive 1is i < d ?.
in and if that.
2 doesn't. work, in our cjant vou c.in do cind do other 3
e l ec t r i t,a )
1, rips 0,
the mcLor generat,or sets and so on.
4 If tt
- 7. peed is noL running, you manually st, art 3
'i
',p e e d.
If ~ the t,urbine i t, not tripped, you manually t, rip
.6
_1 I n turbine.
So you do, in procedure space, all of t.he
=7 ihiogs that Af1 SAC would do too.
So you have got the 1
8 cperator, as a back up.. to the hardware, both in the react.or 7
pro t.ec,t i on system and in AMSAC.
10 That's pretty well imbedded in the procedures in il the 1, raining of the operator right now.
12 DR. KERR:
Thank you.
,Q V-13 MR. NEWTON:
As I indicated, we have made generic j
f' 14 responses on tech specs.
35' Th2s just provides a summary of what we have 16 pr esent ed Lhus far.
The rule requires ANSAC, the NRC has 7
17:
approved 11..
Utilities are implementing i t,.
The NRC has lG.
been rev i ewi n.; or approvi ng those and that. is, bei ng ac tually 19 Installed in plant.i and We have the added basis for our 20 continuing safety awareness of the ATWS rule.
21 T he bottom line of all of this is that the
,12 Wes tinghouse plants are successf ully implementing the 23 requirements of the ATWS Rule.
24 Are there any quest. ions?
25 DR. KERR:
I see none.
X,/
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MR. NEWTON:
loank you.
2 DR. KE l< R :
Thank you, sir.
3 We originally had scheduled lunch f rom 12:30 to 4
1.30, between'the Westinghouse and GE presentations 5
Since we are somewhat, ahead of schedule,I would 6
propose Lo schedule lunch from about a quarter of 12:00 to a 7
qusrt.er oi 1:00.
- p. -
8 Is that going to cause anyone serious l
0 inconvenience?
10 I see no ob]ections.
11 So we will recess until 1245.
12 (Whereupon, at 11:45 a.m.,
the subcommittee (3
.()
13 recessed for lunch tc reconvene at 1:45 p.m..)
14 15 16 17 1D 19 20 1
21 22 23 24
(_I.
25 pm j
Heritage Reporting Corporation (202) 628-4888
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1-Aff I E E E Q Q H H.E E E 1 Q H L
2-DR. KERR:
We will continue with the presentation.
3 by the' representative of the G.E. Owners Group, Mr. Floyd.
.4 MR. FLOYD:
.Thank you.
My name is Steve Floyd.
5 I'm Vice Chairman of the BWR Owners Group and I come'from I
6:
Carolina' Power and Light Company.
.7 We've.been asked by the'ACRS and the staff to make 8
a presentation'on a number of ATWS-related issues regarding 9
implementation.
And these are the topics that we will be 10
. covering today which are very similar to the topics that the 11'
..other NSSS Owners Groups have covered.
' 12 The first item to cover is the status of the} 13 generic reports. The BWR Owners Group submitted the ' 14~ Licensing Topical Report to the NRC in' December of 1985. .15 The SER.was issued,in October of '86. And the appr'oved 16 Licensing Topical' Report was issued to the industry in 17 l February of 1987. 18 We've had two implementation problems. The first 19 one is one that received a fair amount of discussion this I 20' morning and that was the diversity issue related to the ' 21 transmitter trip units and we'd like to spend a few moments 22 a little bit later in the presentation talking about that in 23 more detail. 24 Another--not a major problem, but another slight 25 change.we had to make in some of the designs was providing Heritage Reporting Corporation (202) 628-4888 i
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[ 1 some added testing capability to provide more complete 2 testing of some of the circuitry while at power. Some of 3 the initial designs did not have full testing capability. 4 It's not a point of contention with those utilities and they 5 are proceeding with those modifications. 6 DR. KERR: You are simply asked to provide the 7 capability without discussing how frequently you would test? 8 MR..FLOYD: Yes, sir. That's correct. 9 DR. KERR: The implication I guess therefore is 10 that you should test more frequently than each time you 11 reload, for example? 12 MR. FLOYD: That would be our interpretation as (] 13 well. 14 DR. KERR: Okay. 15 MR. FLOYD: As the Westinghouse Owners Group did, 16 wo sent out a survey within the last week or two and these 17 are the results that we have received. 18 We have thirty-seven reactors which are subject to [ 19 the ATW3 rule. Thirty units are essentially complete. Of 20 those thirty, seventeen are totally completed with l 21 implementation. Eleven units would be complete except for 22 the recent diversity issue on the analog trip units which l 23 has arisen. And two units would be complete with the 24 exception of both the diversity issue and the RPT logic g l l 25 testability issue which I just nentioned. Heritage Reporting Corporation (202) 628-4888 L
~~s (_) 90 1 DR. KERR: What does " complete" mean? Does that 2 mean it's installed? 3 MR. FLOYD: " Complete" means installed, with 4 procedures and training in place. 5 DR. KERR: So you install these with the ATTU and 6 if your efforts do not prevail, you'll have to take those 7 out and replace them by something else? 8 MR. FLOYD: Yes, sir. That's correct. 9 We have seven units-- 10 DR. KERR: Why were you so impetuous? 11 MR. FLOYD: Well, I think we'll get to that in 12 just a minute.
- ( )-
13 D R.. KERR: Oh, okay. I won't be impetuous then. 14 MR. FLOYD: Okay. We have seven units that are 15 incomplete, and by incomplete I mean they have not-completed 1 16 implementation, training or procedures of the baseline 17. requirements of RPS, SLC and ARI without the issue of 18 ' diversity of testability coming into play. 19 They would not be complete even if those were not 20 issues. Of those seven, six of those reactors also have the 21 diversity issue to resolve. 22 That gives us a total of nineteen units that do 23 need resolution of this diversity issue on the analog trip 24 units. 25 I think the point here is to shot. that it was not (^h \\_/ Heritage Reporting Corporation (202) 628-4888 i
,a l 91 1 'one of'two reactors that had difficulty.in interpreting the 2~ diversity requirements of the ATWS rule.as it related to the 3 sensor device. But that. nineteen units have. 4 Another item to point out here is that most of L 5 these units ran'into this difficulty because many of us had 6 the'Barton transmitters or the level. trips previously and 7 the reactor protective system, there were a fair number of 8' reliability problems with the Barton level switches. ~ 9-Utilities replaced those with'the Rosemount which'was a much 10-more reliable device.- 11 Of the units that are currently in compliance with 12-the ATWS rule and don't have'to deal with the diversity ). 13 ._ issue,.the major reason there is that they had not yet 14 switched from the'Barton level switches to the Rosemount 15 devices. 16 .And.a. number of those utilities are now very T esitant to make that switch because they'd like to have-h 17' 18 common equipment in both their RpS'and ARI for maintenance 19 and procurement concerns and are now hesitant to do so. 20 As you'll see from our later discussion, the 21 Barton level trip is an acceptable device to have in both 22 the RPS and the ARI sys+.am and meet the diversity 23 requirements cf the ATWS rule. '24 DR. KERR: Now, wait a minute. It meets the l. 25 diversity--you don't mean, these units are diverse from each 1 Heritage Reporting Corporation (202) 628-4888
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O 92 / 1 .other but rather-- .21 MR.'FLOYD: The staff interprets the Barton level' L 3 trip-device as being part of the sensor and'they do not 4 -' consider that'the likelihood of having a: problem with a 5 sensorgin a common mode sense is sufficiently large-enough 6 such that.you need a diverse sensor, They have a slightly -- 7 different' interpretation. 8 We'll go into this l'n more detail and I think make 9 it clear, the distinction. 10 DR. KERR: I'm sure it's all logical, so I'll just 11-wait.
- 12 -
MR. FLOYD: Exemptions-on the ATWS rule. We've ( [', 13 had one exemption to date which was requested and granted. n >14- .The? original ATWS rule did not take-into account, under the '15 SLC portion..the fact that-there are different diameter 16. boiler water reactor vessels and therefire different. ~ 1-7 capacity requirements for SLC. 18 One utility' filed an exemption request and that 19-was granted. The staff has since revised the final ATWS 20 rule to.take into account the difference in diameters of the 21' vessel so that is not an issue anymore. 22 We do have the potential for additional exemption 23 requests in the area of diversity for the analog trip" units. 24 I'd like to turn our attention now to the ATWS 25 diversity issue. The staff position, as I mentioned a Heritage Reporting Corporation (202) 628-4888
i: r'VlI [ 93 1 minute ago, is that--well, in the case of the Rosemount 2 analog trip unit, the trip unit is not part of the sensor 3 and therefore requires diversity under the ATWS rule. 4 They therefore have concluded that our ARI system 5 lacks diversity and does not comply with the ATWS rule since 6 we are using the same Rosemount analog trip unit in both the 7 ARI and RPS systems. '8 The proposed resolution that has been recommended 9 to us, largely at our urging, seeking a solutionoon this, 10 was to replace the Rosemount circuit board, which is the 11 trip unit portion of it, with an equivalent board that's 12 manufactured by a different vendor, in this case, General (}l. 13 Electric has come up with a design that is a one-for-one 14-replacement with the Rosemount board. 15 The position of the BWR Owners Group is that the 16 trip unit is part of the sensor and therefore it is not 17 required to be diversed by the rule since it performs the 18 same function that the Barton level trip performs. And 19 we'll go into the details on this in just a minute. 20 Our second position is that the ARI system 21 therefore meets the diversor requirement of the rule and 22 does minimize the potential for common mode failure. 1 } 23 The staff's proposed resolution we do not believe i f 24 is necessary to meet the rule and we further believe that it 1 25 offers little or no improvement in core damage frequency. rO d. Heritage Reporting Corporation (202) 628-4888 _____________m___m_m_m_,J
n r i W l .} i A .f}! ..(f 94 i t 1 1 1 I'd'like to turn the presentation now over-to Bill 2' Sullivan who will.give you the basis'for these three 3 positions that we have.. '4 DR. LEWIS: Could-I just--I don't want'to ask you. 5 to interpret _the staff's position, but what did they say to 6 you as the basis for their position? And then we'll hear 7- 'later'what it really is. '8 MR. FuGYD: Basically their position was that the 9 statements of consideration in the rule require equipment 10 ' diversity from sensor output, the final ac uation device. 11 DR.~ LEWIS: .I understand that.- '12 MR. FLOYD: And they consider that the trip unit ( . portion of theLRosemount analog trip unit is not part of the 13
- 14 sensing device but.is part of the signal processing and
.15 therefore needs t be diverse. 16 .DR. LEWIS: And they said to you that getting the 17. same board manufactured ~by somebody else' meets that 16' objective? 19 MR. FLOYD: .Yes, sir. It would, in their .20 opinion--please help me, God, if I'm mischaracterizing 21 anything but their statement was that it would at least i
- l.,
22 address one sub-set of potential common mode failure-in the l l 23 area of manufacturing error. L 24 DR. LEWIS: Okay. Thank you. l [ 25 MR. LIPINSKI: But the sensor itself was not Heritage Reporting Corporation (202) 628-4888
a'. L 4 l -) 95 (_/' 1 required to be diverse. 2 MR. FLOYD: That's correct, sir. 3 DR. KERR: Well, you understand the rule says 4 that. 5 MR. LIPINSKI: I know that. 6 DR. KERR: Yeah, okay. 7 MR. SULLIVAN: My name is Bill Sullivan. I am 8 from G.E. I am a Principal Engineer in our Reliability 9 Engineering organization. 10 Before I get started, let me kind of set the stage 11 here. First of all, I'm going to be only talking about the 12 diversity in the analog trip unit. The question of overall (')T 13 diversity in the other equipment in RPS and the ARI and the L. 14 associated reliability and common cause failure reduction is 15 really not an issue here and I think we're in agreement with .16 the staff on that. 17 What I plan to present is basically three points. 18 Steve mentioned one of them. The first point, just from a 19 legalistic point of view, we feel the ar.alog trip unit meets 20 the rule in the sense that the rule does not require design 21 and manufacturing diversity between the RPS and the ARI. 22 Secondly, looking at it in another light, you can 23 say functional diversity and equipment diversity, and I will [ 24 go into that in a little bit more detail, of the analog trip 25 units within the RPS currently exist. u/ Heritage Reporting Corporation (202) 628-4888
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1: We had' identified one. case, and that's'a loss.of 2 Efeedwater transient, here.the automatic scram depends 3 basically on'one:scr a parameters. And that's level. And n 4 I'd like.to share i th you some of our results of that- '5 assessment. 6 I don't plan to read this. I think~you can take a 7
- quick stand.
This is an excerpt from the ATWS Task Force ,8 recommendation. Basically what it's saying is the 9 vulnerability of scram system, the bistable calibration 10 errors an'd common cause failure errors.is recognized. 11 It also recognized that monitoring of sensor 12 output and frequent testing of the trip value ensures common 13 .cause failures can be detected. 14 The-final rule, as given in the statement of. ~15 . consideration, the bottom line says the sensors need not be 16 of diverse or of manufacturer. 11 7 Now,.the real issue I.think, as Steve pointed out,. 18 issthe fact that we have'with the staff is what is included 19 in the sensor. 20' What I have here-- 21 DR. KERR: You've tried this argument on the staff 22 and they didn't accept it, I *ake it? 23-MR. SULLIVAN: The: s right. l 24 DR. KERR: That didn't make you wonder about the 25 logic of forcefulness or persuasiveness of your argument? O! Heritage Reporting Corporation (202) 628-4888
g-j m. 4 ry i i 'd' 97-g3 '.1 - MR. SULLIVAN: I haven't been' persuaded. And I'm 2- 'having a hard time -you'know, I can understand the arguments 3t that we've' laid out here and I think it's a pretty strong- '4 ! case that ne have. I'm not too sure that I really P 5-understand some of the overlying objections the staff has 6 for this particular issue. .7 DR.-KERR: Okay. 8 MR. SULLIVAN: Nhat I have here is the two types 9' lof level sensors that we normally have.in a BWR. The first '10 type is a level switch. This is usually a Barton or Yarway. 11 This is the one that Steve had referenced before. 12 The other type is a transmitter trip unit which (] 13 includes a' transmitter and, of course, a trip unit-here.
- 1-4 The key thing here is-both of these devices j
I 15 provid, a-bistable output here and here to the RPS. Some 16-plants have level switches. Some plants have gone to the 1? more reliable analog trip units. But basically both of (18 these sensors are accomplishing the same function. We feel 19 'this is a little bit more reliable and reflects the current 20 state-of-the-art. 21 DR. LEWIS: Forgive my ignorance. What's an LT.in 22 that-- 23 MR. SULLIVAN: LT is level transmitter. 24 DR. LEWIS: I see. Okay, fine. So it's a level 25 transmitter with a bistable interpreter. Heritage Reporting Corporation (202) 628-4888 h___.
I r. . f' (_) 98 1 MR. SULLIVAN: Right. i 2 And the key thing also here is both of them have a 3 ' bistable trip device. Right here and right here. Which is 4 supplying inputs to your logic. And this logic could either 5 be RPS or ARI. 6 DR. LEWIS: I'm trying to understand whether they 7 measure different things. A level switch is also-- 8 MR. SULLIVAN: They measure the same thing. 9 DR. LEWIS: Okay. Thank you. 10 MR. SULLIVAN: Yes. .11 MR. LIPINSKI: Would you discuss the testability 12 of each of these devices and which one is more amenable to (^T 13 testing? %.) 14 MR. SULLIVAN: Well, this s currently right now 15 per tech spec. This is calibrated on an eighteen month--or 16 every quarter, and you do functional testing every month. .17 This is calibrated every month and along with doing i 18 functional testing every month. This calibration is a 19 relatively simple calibration. This right here requires you 20 to hook up a source and provide a trip of that particular 21 switch. I 22 MR. LIPINSKI: That's why I asked the question. l 23 MR. OAKES: Do you have any data on the relative 1 24 reliability of these two devices? 25 MR. SULLIVAN: We have--on the reliability we I ; k-)-(O. 1 Heritage Reporting Corporation l (202) 628-4883 l
___ y 1 e-po. q H b, a f 4 h)s 99 '1' -have,:of course, done a. study of.this module here-and"it's 1 1 2-documented -in.one;of our reports where we've used the feest Lij 3. part type reliability and came up wi.th the overall l 4 reliability of the. boards in the various' trip units. L L 5 As'far'as the level switch, there's a lot of level- ? and we_have experience there. I: don't-6 switches out of there ,7-have an exact difference in those two reliabilities. I 8 would. offer opinion. I'd say you were talking about in the '9 ' order of a factor of 3 difference. 10 MR. LIPINSKI: -But if you take into account the 11 test interval, the beta rates were same.. You've got a 12 shorter test interval on the transmitter unit, you would () 13 have a higher reliability. -14 MR. SULLIVAN: Availability. 15-MR.- LIPINSKI: Availability,'right. 16 -MR. SULLIVAN:. Availability would get into your 17-test interval,_ incorporating test interval, right. 'l-8 So argument number'one. We are saying that 19 whether it's a level switch'or whether it's a transmitter 20 trip unit, we are talking about a sensor, the rule 21 legalistically states that the sensor does not require it to 22 be of diverse design and manufacturer. 23 DR. KERR: Well, now, what would happen if you put 24 the transmitter slast ATU in a box, painted in black, and 25' you just-had two output terminals and you put a label on it Heritage Reporting Corporation (202) 628-4888 .-_.-___________mm_-..____ _____-____-.______-___.-_.--_____m.m._______- .__m_--
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V is 100 .j L 1' ~ that said " sensor." 2' MR. LIPINSKI: Well, that's what he's arguing i 3-about. 4 Dh'. KERR: Would the.staffLaccept that then?: i '5 Because they don't look at details. They said this morning..
- 1 6
'AndLthey might not ever open that box. 7 MR. SULLIVAN: This is the box that we would like 8 to blacken out-- / '9 DR. KERR: ,I mean did you try that? Did you take 10 'them:this box and-- '11 MR. SULLIVAN: Yes. 12 DR.' KERR: And they didn't-- - 1'3 MR. SULLIVAN: I wasn't at that.particular 14L presentation..One of our electronics people was there.- -15 D R. K E R R : You see, an electronics guy will always 16 open it up and show them the internals. -17 MR.'SULLIVAN: Yeah. DR. KERR: That's the mistake you made. 18' 19 MR, SULLIVAN: Okay. We should have shown this j 20 box here and this box here. l 21 DR. KERR: That's right. 22 MR. SULLIVAN:
- Okay, i
23 DR. LEWIS: Are you selling black boxes? j 7 -24 MR..SULLIVAN: I'm selling sensors. 25 I'd just like to point out that I think that's the .O: Heritage Reporting Corporation (202) 628-4888 r l .!?
'k. ! : ]..- e ,W 'U) 101. n b 1 answer to.the question that.you asked'me earlier about.why 2. could-nineteen reactors. select apparently theLwrong device.' 3 When we' read.the ATWS Task Force recommendations, it.did-4 Ltalk;about.the reliability of a bistable, the fact that you 5 frequently calibrated and' tested them. 6 And.the wording that's in there certainly does 1 7 suggest that that entire bistable feature.is considered to 8. be part of the sensor. Therefore, when the staff stated-9 their position, that' because there:is some signal 10 conditioning going'on there,- that that is not part of the .11- -sensor, we were surprised by that. 12' DR.-KERR: Okay. q(] 4 13 if R. SULLIVAN: Let me also go back here because I
- 14
.think one question was brought up this morning about' 15 reliability. And if we were to state, and I'll take your 16 suggestion, Dr. Kerr, of calling this a box here, and say if 17. ~this box was-a Rosemount or a Brand X, which'I think the 18 staff has recommended, how would the two reliabilities '19 compare? f 20 From a reliability point of view, there are--I L L 21 mean from a configuration point of view, there are - ) l: 22 differences. From a reliability point of view, there really 23 is no basic difference because you have the same basic j l 24 ' number of components.on the card. The same basic major 25 contributors to the overall card unreliability. Heritage Reportipg Corporation (202) 628-4888 L-,_-_.-___,____.___.___._______m_.
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(/ 102 1 So I don't see any real difference in the reliability of whether you put a Rosemount here or some 2 c 3 Brand X which is of similar de-1gn that you could plug right 4 in as your sensor output real conveniently. 5 Now, second point. The other was more L 6 legalistically. This is what I consider more technically. 7 Well,.what about the sensors themselves? When you look at 8 the RPS for BWR you'll see there's basically three different 9 types of sensors that cause an automatic scram.
- Flux, 10 position switch, and analog trip units, analog transmitter 11 trip units.
12 And to demonstrate this, or to show it a little ~ (_)g 13 bit in more clearer terms, what I have here, and hopefully L 14 this isn't too busy, here again I want to concentrate on 15 sensor diversity. I'm not saying that the logic is going to 16 be different from one transient to the next, only talking 17 about sensor diversity here. 18 What you have is three different types, which I am 19 going to call functional diversity because they perform 20 three different types of functions. One falls into analog 21 transmitter trip unit category. And that would be your 22 pressure and level. Your other would involve position 23 switches, which is turbine control valve closure, stop valve I 24 closure, and MSIV closures, which all cause automatic scram. l 25 The third one are inputs from flux and radiation ("J i a l 's_ 1 Heritage Reporting Corporation I (202) 628-4888 1
7 ,7% '() 103 o 'l sensors in terms of APRN and-high radiation.- 2. Listed here are the~various major' transients and 3. . major meaning the anticipated' transients that we normally- ~ 4 .look at. != E 5 The numbers here refer.to the order.in which one 6 would expect these sensors to be tripped. For MSIV closure, 7 'the first' trip would be your closure of the valves would 8. cause'a position switch scram. If that didn't work, then .5F you would have flux to pick you up and cause a scram. If- -10 ' .that didn't work, then you would have pressure that.would- ' 11-also pick up. And level would be your fourth level. 12 As you see here, there's various ones here. .I .( { 7; 13 think the minimum one we have here is for pressure. regulator 14 failure; primary increase. -In here you have flux and' 15 pressure so'you still have two diverse ways of~ shutting ' 16. down the reactor. Remember, this is the' place where your 17 transmitter trip units are. These right here are diverse 18 from the transmitter trip units. '19 However, we've identified one case where the 'evel 20 here are the MSIV closure and pressure is dependent on.ne 21' level sensor. Otherwise in order to get MSIV closure for 22 loss of feedwater event, you must have a level trip i; order 23 to get an MSIV closure, and then MSIV's will cause the plant 24 to scram. If you get an MSIV closure, then you should get a 25 high reactor pressure level scram. But here again it's all i Heritage Reporting Corporation i (202) 628-4888 _____-__--_-__--__a
t /' N. \\ 104 1 dependent on level. 2. So looking at that specific evt.nt, we performed 3 what I'd consider a mini risk assessment. Ana like I say, 4 we're only looking at one event here. Loss of feedwater 5 event. And what we have found is basically three separate 6 sets of water level' trip units. And by set'I mean four 7 sensors. One of these sets happens to be ARI. The other r 8 set is the RPS and the other one is the set that causes MSIV 9 closure. 10 So in total, you are talking about a minimum of at [ 11 least six individual trip unit failures in order to prevent p 12 scram. And this would be automatic scram. ,.() 13 However, when you look at the event itself, and 14 we've looked at basically what happens if you lose Level 3 15 or the RPS level, ARI level, MSIV level and took it all the 16 way through, what we find is the operator has at least 17 fifteen minutes to initiate manual control rod insertion or 18 manual scram. 19 He has diverse reactor water level indication. 20 This is provided by the feedwater. It uses the diverse set 21 of sensors. I think in some plants they use what they call l 22 a GMAC-5000 which is diversed from the Rosemount analog l 23 transmitter trip units. 24 He also will eventually get an APRN downscale 25 alarm which will also be another indication to him, r'T %) Heritage Reporting Corporation (202) 628-4888 -_______________-____D
r~ a t - b 0.' , i s- -j? ' V( S c [ t 105 V a" ~ 1. Combined.with that we have EPG's;or Emergency Procedure L,: 2 ' Guidelines in place which provide adequate or appropriate '3 operator guidelines on what kind of' action he should :take in b 4 ~ response to these indications here. H" 5 Now, before you tell me to sit down, because'I 6 presented a very low number here, and attempted to quantify 7 a common cause failure, let me characterize this number a 8 little bit, because I think it needs to be put in the proper 4 9 context. 10-First of all, it's only for the loss-of-water L 11 inject' ion or loss-of-feedwater event. Secondly, it doesnt t 12 include other contributors, the scram unreliability, like ff 13- .the trip logic or the scram contactors, which also could be 14 major contributors'to overall probability of completi'ng loss ~ ,1 1 15-of the level indication. We are only looking at the sensors 16 .here.- And their contribution. 17 Also, this number includes the probability of the 18-operator taking action. Now, as far as the quantification 19 is concerned, how we quantified this common cause failure 20 potential. We basically used what's out in the current 21 PRA's out there. What other people are using. We used l 22 realistic estimates of the probability of an operator taking y 23 action, giving the indication, the procedures he has.in 24 place and also the timing. 25 MR. DAVIS: Did you use the beta factor model--
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/~(N / 106 1 MR. SULLIVAN: Yes. 2 MR. DAVIS: What did you use for beta? 3 MR. SULLIVAN: I think it was something like .1 { i 4 was our beta factor. 5 MR. DAVIS: No. 6 MR. SULLIVAN: Okay. So what we are concluding 7 from this with the loss of feedwater event here, we feel 8 it's a minor contributor to the overall-ATWS failure 9 frequency and additional diversity in the analog trip unit 10 is really not justified. 11 With that, I'm going to turn it back over to Steve 12 and he will continue. (")T-13' DR. LEWIS: If I could just follow up on Pete's l N_ 14 question for'a moment. I 15 Did you use the beta method because you believe 16 it's a fine method or because the availability possibility? 17 MR. SULLIVAN: I think we used the beta method 18 because we have been using that method in some of our PRA's 19 out there and we find that, you know-- l 20 DR. LEWIS: That just moves the question back in 21 time. 22 MR. SULLIVAN: The what? 23 DR. LEWIS: Never mind. I've never heard any 24 rational defense of the beta method. 25 MR. SULLIVAN: Okay. I don't know if I would be l (~% i \\ l U., l Heritage Reporting Corporation (202) 628-4888 L r
p-lii- .+ >e O 'bs - (,J.l 107. .) 1. the one to give that-- ) 12 DR. LEWIS: I won't even ask. i. 3 DR.'KERR: Have you ever tried to convince the' 14 staff that this push toward diversity.might make things less 5 reliable, because they said they'd listen to argumentsaof 6-
- that. kind?
7L MR. STALTER: Yes, sir. That's our next slide, 8 which I'm about tofgive to you. 9 DR. KERR: No, but I~mean, have you tried to y 10' convince'the' staff before you '.ry to convince us? 11 MR. STALTER: Yes, sir. And we were basically 12 told that there was no way to quantify the amount of [( f; 13-detriment that we might see from putting in this card. 14 'As you'll see, I don't think they can quantify the-15-amount of benefit that they hope to gain from us putting in 16-this card either. So we really can't talk quantitatively on -17 this issue, I don't believe. Neither side can. 18 DR. KERR: Well, if.you can use beta factors, you i 19 can talk quantitatively without it meaning very much, but I 20 don't'see why you couldn't--maybe there's a beta factor for 21 maintenance and for stocking a-lot of different parts rather 22 than one or two. You need some ingenuity. .I 23 MR. STALTER: We have not gone into that, sir. 24 DR. KERR: Okay. 25 MR. STALTER: Given the results that we got from Heritage Reporting Corporation (202) 628-4888 i l l 1 -I '^ .__.__1___
E L; i ~s 1 u 's. rd' 108 1 UG.E.-and the other reviews that we've done of the ATWS rule,. 2 we' asked ourselves, should this proposed staff res'lution be o 3 implemented. And onefreason--this is rather, the staff's j 4 reason that could be.a reason for putting it~in would be .) 51 that you'would hope to get some reduction in common mode 6. failures that are associated with the fabrication process.- 7 -If.you look at the two cards though,. you are 8. essentially dealing with the essentially identical 9' componente. You are just having G.E.'s vendor fabricate -l'0 .them, put them on the card',' as opposed to having Rosemount 11 do it. Solyou'really are talking about a manufacturing or 12 .fabr'ication' common mode failure' concern here. ' f ); 13-DR.-KERR: By the way,: are you sure that G.E.'and 14' 'Rosemount don't.get these from the.same supplier? 15 MR.'STALTER: We are confident of that. I've 16 . asked that question myself. 17. DR. KERR: Okay. 18 MR. STALTER: The negative. side that.we could -19 think of is that although we have no reason to suspect up 20 front that the G.E. card won't be a reliable card, it really 21 doesn't have a proven history behind it. We've had the 22 Rosemount cards out in service for' years and they have 23 proven to be reliable and we are somewhat concerned about '24 taking a card which has had a limited amount of field application thus-far and putting it in its place. 25 Heritage Reporting Corporation (202) 628-4888
D u 109 'l Another concern we have really counters the pro p
- 2 side that I just telked about and that's the fact that there 3
is no manufacturing facility set up to man.facture the G.E. 4 cards. They are not readily evailable as is the Rosemount (: L 5' card..In the case of the Rosemount card, we could call .l 6 Rosemount and get one Federal Expressed out tomorrow if we '7 needed it that quickly. 8 .For G.E..-we have about a six-month lead time 9 because these are manufactured in a batch process. They 10 have t'o cont'act a vendor who is willing to fabricato these 11 and then he has to set up his manufacturing process before 12 he can. start punching these cards out. ,-lm. 13-The negative side on that that we see is with an j v 14 in-place manufacturing process as exists with the Rosemount 15 cards, you have a continuous quality assurance, quality L 16 co,ntrol fabrication. feedback mechanism that is further 17' supplemented by field experience which can correct L 18 manufacturing errors. { 119 If you are going to do that on a batch process and 20 if we do go this route, we are talking nineteen units that I. 21 need ten cards each, four for pressure, four for level, and { 22 a couple of spares, you are looking at a batch process of Lct i 23 about two hundred cards. You are just not going to get a p 24 lot of quality assurance, quality control feedback loop in i.; 25 place on such a small scale manufacturing process which will ( );
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c.a-Heritage Reporting Corporation e (202) 628-4888 e 's
Y $O fM -w -"'~ agf 's - p4 1 js: 110 1 take place over a few month's period. (. 2' DR. LEWIS: How many cards has Rosemount sold? 3' HR. STALTER: They have a production line which h .4: is a continuous operation. 5 The third item is we believe that it raises the L6 potential for common mode failure. 7 --a change out of a card, should a card prove to 8 be defective'or whatnot. He's going to be looking, from the ~ 91 ' outside, at what appears to be two identical Rosemount 10' cabinets. One will have a Rosemount card in it. The other 11 1 ' one will-have a G.E. card in it, and we are concerned about 12 the possibility of crossing those cards up, and, as a m_-) _ 13 minimum, the complexity that that places on the procurement
- 14' and the maintenance process in the plant.
15-I say "high cost." It isn't particularly high. 16~ It's going to cost us about $170,000- per reactor to change 17 these cards:out. That' includes procurement of the cards. ~ 8: 1The preparation of the design modification and the reviews 19: associated with that as well as changes to the maintenance 20 and procurement procedures. j 21 DR. KERR: And the card itself costs about how 22 much? 23' MR. STALTER: It's about--it depends on how many ) 24~ we get fabricated on this batch basis. It's going to be 25 somewhere--and the number is around $8,500 to $12,000, 7.. .) Heritage Reporting Corporation (202) 628-4888
1 ~ r- - i i L V if :f'%l, $M 111 1. depending upon'the exact number that we wind up producing. 2. So in round. numbers,_about $10,000 a card.
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3 But the' reason why it does kind of rub us the L 4 wrong-way is that we really don't see any substantial safety 'S . improvement as a result of doing this, and we do see some 6: negatives up here. 7 Our last concern is that it establishes a S diversity definition that we believe is inconsistent with 9 the rule. We think the rule right now does exempt this 10' device in that it is part of the sensor and should be 11 exempted. 12 The other concern we have, which is somewhat ); '13 'related to this item, is--and it was referred to this + 14 morning, that how far do we go with this? Is' achieving 15 manufacturing diversity enough to address common mode 1 16 ' failure? Or will six months from now the concern be, " Gee, 17 this diode is the-same as that diode. This transistcr is 18 the same as that transistor." 19 I was happy to hear from the staff this. morning 20 that.they do not intend to go down to the passive componen+ 21 level and that the concern rests solely with the active 22 components. Which raises an interesting point. The only 1" 23 active components that are in the analog trip units are the ,1 24 relays. And in the particular case of application we are 25-talking about in the RPS system, the relays are energized to A. g Heritage Reporting Corporation (202) 628-4888
i i bI< ?- 112 1 actuate and in the ARI system, they are currently--excuse 2 me. They deenergize to actuate in RPS and they energize to 3 actuate in ARI. 4 So the only active component - that we are concerned 5 about since we are not concerned about passive components, 6 does have a form of diversity in the form of energization 7 state. 8 Therefore, you would think that there would not be 9 a common mode failure with regards to active components that 10 could result in diverse energization states. If you had a 11 failure that would result in both relays being actuated, you 12 would get a trip from the ARI system. If you had a failure .<'s (,) ' 13 which resulted in both relays from being deactuated, you 14 would get a trip from the reactor protective system. 15 DR. LEWIS: This is a dumb question, but do 16 Rosemount and G.E. get their relays from the same source? 17 MR. STALTER: That I don't know the answer to. 18 sir. 19 MR. DAVIS: You quoted the $10,000 for the G.E. 20 card. What's the cost of a Rosemount card? 21 MR. STALTER: It's about $2500. And the 22 difference I think being in that the G.E. card was a 23 special.ly designed card for this issue and is manufactured 24 in a batch process with a lot of set-up costs to get ready 25 to make the runs. O l Heritage Reporting Corporation (202) 628-4888 L___.___ __.______________________________________________________________________________O
a. i KV 113 1 MR. DAVIS: I don't see any discussion of one of 2 the staff's contentions regarding aging. How do you respond 3 to the possibility that the cards may experience aging l 4 faults at about the same time? 5 MR. STALTER: And I don't have an argument for 6 that. 7 Bill, maybe you do. 8 MR. SULLIVAN: I know one thing on the elays, for 9 example. When you talk about an energized type relay versus-10 a deenergized type relay, a lot of the aging things that 11 we've seen, like rubber components or some type of material 12 inside the relay could be subject to a higher type wear-out () 13 when you are in an energized state. Because you've got 14 heat, you know. A lot of heat there. 15 This is kind of what happened at the famous event 16 they had where the twelve relays failed and, you know, it 17 was due to the heat which caused the relays to fail in a 18 deenergized condition. Where when you are in a deenergized 19 condition during normal state, you don't have that condition 20 there and you are probably not going to be as subject to as El much wear-out as you would. 22 So you've got some diversity I feel just in the 23 two different types of operations. 24 MR. DAVIS: That second question. Item No. 3 25 bothera me a little bit. I had been led to believe in the O Heritage Reporting Corporation (202) 628-4888 l
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\\/ 114 1 past that by having diverse components, you actually reduce 2 failures from maintenance because different methods have to 3 be used on the different components. 4 But you are arguing here that it, in fact, 5-increases maintenance errors. 6 MR. STALTER: In point of fact, what happens here 7 is that because these cards are a one-for-one replacement 8 for each other, they perform the identical function, there 9 is no change in the calibration procedure required to 10 calibrate either the G.E. card or the Rosemount card. 11 That's how similar these cards are. 12 MR. DAVIS: Wouldn't it be possible to make ~ them (f 13 so you couldn't replace them incorrectly' 14 MR. STALTER: I don't know the answer to that 15 question. I think the design would probably have perhaps, 16 you know, made such that it couldn't be a one-for-one 17 replar:ement in the cabinet, and now we are talking about 18 ript ag out the Rosemount system and putting in some other l l 19 total new design, which would, of course, be a much higher 20 cost. We're trying to look for a lower cost alternative to 1 1 21 that. 22 MR. DAVIS: Thank you. l-23 MR. LIpINSKI: Let me ask a question of G.E. l 24 Designing of the new card, you can come up with 25 higher reliabilities depending upon what stress factors you Heritage Reporting Corporation (202) 628-4888 l l lE
i" l;l r i E ?t n, p; L Q. 115 j 1 , assign to the different components. n Rosemount, I assume, used. commercial stress' 2 -. L 3-factors whereas.if you went to MIL-type specs you.could- \\, ' design a' card with much higher reliability depending on what 4. 5~ stress factors you assign to the different passive 6 components. 7 _Do you know if that's been done? .8 .M R. SULLIVAN: I know the study that we did for 9 the--in fact, we were involved in the original Rosemount 10 study where we did the reliability and we were using values 11 .out'of the MIL standard handbook on various components. 12 Basically, as I mentioned before I think, it's my .()' 13 ' feeling that--I'm not familiar with if we've done a specific 14 study for the G.E. card itself. But I think if one was 15 done, you would expect to see basically very identical type-y 16 results. 17 MR. LIPINSKI: That's what I was afraid of. 18 Because that would be one of the benefits that if G.E. was 19 doing it they might do it to a higher set of standards. But 20 if it's still commercial grade, they'll come out the same. 21 MR. SULLIVAN: And I can't verify specifically 22 those two grades, but it is my judgment the two would be 23 pretty close. 24 MR. STALTER: A quick summary then on the 25 diversity issue. We believe that the trip unit, the analog Heritage Reporting Corporation (202) 628-4888
1 J 1 1 ) /~'s 116 l v t I 1 trip unit is part of the sensor. And therefore does not 2 require diversity for the rule. Diversity is not limited to 3 equipment diversity by the ATWS rule. The body of the rule 4 itself states diversity. The statements of consideration 5 places a requirement that equipment diversity were 6 reasonable and practicable be applied. 7 The staff position on diversity requirements, 8 which was attached to the Safety Evaluation Reports which 9 they sent to us allows combinations of allowable methods 10 where total hardware diversity is difficult to achieve. 11 Some of those combinations were functional diversity, as 12 well as manufacturing and equipment diversity. /"N (_) 13 Recent staff decisions--their, west communication 14 to us requires total hardware diversity regardless of 15 difficulty cost or benefit. 16 Fabrication for diversity for the Rosemount trip 17 units, in our opinion, provides negligible safety 18 improvement. Our conclusion is therefore that our current 19 design does meet the ATWS rule. 20 DR. KERR: If the staff would prefer not to answer 21 this, they can say so. But do you accept their 22 interpretation that your recent staff decisions require 23 total hardware diversity regardless of difficulty, cost or 24 benefit? 25 MR. NEWBERRY: No, I don't think I would interpret Heritage Reporting Corporation I (202) 628-4888 ) 1
[ \\' r k l' 117 1 our last communication that way. I think the last 2 communication, if I could take a crack at summarizing it, is 3 the design as we see it does not meet the regulation. That 4 is, it is not diverse. I think one primary--one of the 5 primary disagreements we have is simply in the definition of 6 sensor, to be begin with. I just cannot accept that a 7 bistable located hundreds of feet from the sensor would be 8 considered part of the sensor itself. 9 DR. KERR: If it were five feet away could it be? 10 MR. NEWBERRY: It's not even integral to it. It's 11 a device which I've always heard termed a "comparator." A 12 comparison device. A bistable, part of the signal n (_) 13 conditioning. There are many definitions which would 14 disagree with some of the written and published definitions 15 which would disagree with some of the thoughts found in--I 16 guess what Steve put up here, the ATWS Task Force. i 17 DR. LEWIS: I don't understand a criterion based 18 on distance or integration because there's functional 19 integration and I don't know why two feet are okay and one 20 hundred feet would be bad. 21 One is getting very arbitrary at that level. l j 22 MR. MAUCK: Well, I don't think there was ever any 23 distance criteria. I believe that the Barton level switches 24 that they had up there, it was given that since the trip 25 unit, if you want to call it that, was part of the body of Heritage Reporting Corporation (202) 628-4888
L -k 118 1 the Barton level switch, that that would be counted as part 2 of the sensor, but in this case if the signal conditioning 3 is not part of the actual body of the level switch or some 4 other switch that it is not considered to be part of the 5 sensing unit. The classic definition of a sensing unit is I 6 something that's out there sensing a change in parameter and 7 that's not what the trip unit is doing. 8 DR. LEWIS: But this is really beginning to get 9 into angels dancing on the head of a pin. Because we're 10 beginning to' lose sight of the purpose of all this which as 11 has been said many times to ensure the reliability of the 12 system. And when the definition of what is integral depends [) 13 on whether they are in the same case or not, you have to ask 14 what contribution the casing makes to the reliability of the 15 system, if you are going to be serious about it. 16 And I worry about the logic. Maybe we made a 17 terrible mistake long ago when we let the rule go through in 18 its present form. But one is making very, very rigid--and 19 maybe you have no choice. Very rigid interpretations of the 20 wording of the rule in the same way that on the Hill one 21 makes rigid interpretations of badly created legislation. 22 But that doesn't make the country a better country as a 23 result of it. 24 I wonder if I could ask a separate question, Bill, 25 since I have the floor for an instant. Of the staff. i ,s (' _/) Heritage Reporting Corporation (202) 628-4888
y. ( ; ,m.(j" 119 1 DR. KERR: Well, let me think. Yes. 2' DR. LEWIS: Thank you, sir. 3 Long ago, this becoming a life's work, of course, 4 as it is for you too. Long ago--I'm putting on my " boy 5 inventor" hat now. Long ago the question was raised of 6 whether one way to ensure the reliability, and this is 7 independent of the rule, the reliability of systems of this 8 kind, is used in the computer business all the time, and 9 that is self-testing mechanisms. When you turn on your PC 10 it tests itself. When I turn on my printer, it tests 11 itself. It runs through all its functions. It takes a few 12 seconds to do that. And everything responds and says, "I am fi 13 here. And I'm working." %A 14 And for many of these systems, which include a 15 -fair amount of electronics, both passive and active, you can 16 test nearly everything in that way. So that you could have 17 a continuous green light which tells you that everything 18 except the few things that would actually trip the system 19 has been tested on a continuous basis. 20 This was brought up to the staff several years ago 21 and I think Bill was present at the time and the answer came 32
- back, "No, we can't permit that, because that would involve 23 adding extra complexity to a system we'd like to keep 24 simple."
As I recall, that was the rationale for not taking 25 the idea seriously. Heritage Reporting Corporation (202) 628-4888 I
( + 120 L. s 1 I'm'not proposing that we redesign trip systems.at 2 -this point, but is'there.any philosophical' response to self.
- L testing as a. road toward reliability?
I'll ask anybody that 4 que'st' ion'. ~ 5 MR. SULLIVAN: There.are plante out there, like U 6' one of.our Clinton plants out there,- the solid-state plant, 7 which has self-test. features built into it. 8 Also I want.to mention, which I probably kind of 9-sluffed over, is'the fact that one of the reasons why we're L10 saying that theLanalog trip unit is a little bit more u. 11 -reliability than level switches, it has some self-test 12' . features in it, in itself. It's not fully self testing. (I. 13' DR. LEWIS: No, you can't do_it. 14 MR. SULLIVAN: Right. But there are parts of the t 15 trip unit which has self-test features built into it. 16' ~ MR. MAUCK: 'I guess there are plants that are 17 coming through or have just gone through the licensing train '18 .that do have'a computerized micro-processor based safety 19 systems, and they have provided pelf-test systems, and the 20 staff is looking at those closely, and I guess we are 21 favorable towards self-test systems 22 DR. LEWIS: I see. Well, that's a change of 23 positi.on then, because it was really very negative a few 24 years go. 25 MR. MAUCK: Yes. But with these computerized Heritage Reporting Corporation I (202) 628-4888 1 i U _____i____1__.L______._____.______________________________________________.__________ _j
i N j ikh 121 7 IL programmable safety systems we are insisting that b y 2 verification and validation of the software be performed by 3 'theLvendor. So there is that check on the actual software-4 being used for these systems too. 5 DR. LEWIS: You are insisting on verification of 6 the software? 7 MR..MAUCK: Yes, sir. l '8 DR. LEWIS: Verification, of course, of the 9-software business has many meanings. 10 MR. MAUCK: Oh, it does. Right. Yes. We use 11 IEEE-7432 as a guide. 12 DR. KERR: Excuse me. I want the record to show .( ) 13 'that I did not authorize that question. -14 DR. LEWIS: You will not authorize that question? 15' DR. KERR: I didn't authorize it. I authorized 16 the previous one but not that one. 17 (Laughter.) 18 DR. LEWIS: But I didn't ask that. He raised the r 19 issue. I appeal. 20 But verification is a tough business. It's not as 1 21 simple as the word seems to be. i i 22 MR. MAUCK: No, it's an extremely tough business. b 23 I'm in agreement with you on that. 24 DR. KERR: I want to pursue the earlier question 25 of what is a sensor just a little bit to see if I understand Heritage Reporting Corporation (202) 628-4888
l ' l(~') s \\/ ~ 122 1 the staff's position. 2 The impression I got, and correct me if I'm wrong, -3 is a pressure sensor should set pressure and should have 4 pressure as.an output otherwise it has some signal 5 processing in it. 6 MR. MAUCK: No. The pressure sensor should be 7 sensing the pressure and in this particular case it has a 8 current as an output. It's the changeover from the physical 9 medium to the electrical medium. i 10 DR. KERR: I thought the problem here was that 11 this had something coming out different than what is being 12 sensed that made it not a sensor. What is it about the n ( )~ 13 input / output that-- i 14 MR. MAUCK: Well, you are talking--I guess in the 15 ATTU, if you include that as the sensor, you also have a 16 plus and minus 2J. volt power supply as the sensor and then 17 you can take that up to the 120 volt bus into 480 bus. So 18 you have to draw the line and the line drawn on the sensor 19 is the actual device that's converting the physical medium 20 to the electrical medium. And what's within that body of i 21 that particular device. 22 DR. KERR: I'm trying to find out what the device l 23 is that you call a sensor. Where is the-- 1 l l 24 MR. MAUCK: It's the transmitter in this 25 particular case. l Heritage Reporting Corporation (202) 628-4888 1 l L______._.________
Q. A/_ 123 1 DR. LEWIS: Let me make sure I understood you. 2 You did define it. You said it was the-object which sensors 3' the parameter of interest and. changes it into an electrical 4 signal. Is that your definition of a sensor? I.think 5 that's what you said. 6 MR. MAUCK: That's within that particular case, 7 yes. And it's in the particular body. 8 DR. LEWIS: And it's within the particular case. 9 In other words, it cannot send a signal out that is not 10 electrical and then convert it into an electrical signal and 11 still be a sensor? 12 MR. MAUCK: No. I wouldn't think so. There you f )). c 13 are either talking a current-to-current converter or an I to s. 14 V converter or in another case, a V to I converter. You are 15 talking power supplies. You are talking operational amp, 16 bistables relays, and none of that fits the classic 17 definition of a sensor. 18 DR. LEWIS: I'm talking about fiber optic 19-connections. They are not sensors anymore? Electrical-- l-20 MR. MAUCK: Well, yes. In a particular case where 21 they are actually sensing a source of light, they would a 22 sensor. l 1 23 DR. LEWIS: I think you are in trouble with this 1' l 24 definition. l l 25 MR. MAUCK: Well, I didn't say that this was Heritage Reporting Corporation 1 (202) 628-4888 ) i
/Y $J' 124 r: I com'ing fromLany textbook. 2 DR. LEWIS: I know. You did'it on the spur of the 3-moment. 4-MR. MAUCK: You realize that. 5 DR. LEWIS: I think' the point is being made and'I 6 think it's correct. That if you really try to define these 7 things you are going to be in deep trouble. 8 MR. MAUCK: It's extremely difficult. 9 DR. LEWIS: But if you made electrical signals, 10 I'll give you fiber optic cables, and.if you include fiber - 11 optic. cables I'll give you acoustic connectors. And I'll 12 give you strings and wires, for that matter, if it comes to W pyg 13' that. And there just is no good ~ definition except 14 functional. 15 MR..MAUCK: True. 16 MR. LIPINSKI: And then'you get into the question 1 ' 17 of the separation distances. Whether it's five feet away or 18 whether it's in the same case. No single sensor will send 19 out an electrical signal unless it's got a electric crystal 20 in it. Even in his case where he says he has a milli-amp 21 signal, he has to have a power supply to get those milli-22 amps out. 23 And also you'll have sensors that are switches. 24 You don't get currents through the switch unless you provide 25 some external circuit to it. Heritage Reporting Corporation (202) 628-4888 m
L/ o ~( Y l %= 125 1-DR. LEWIS: On the'other hand, I can do it with an 2 optical lever and not have a power supply in it. n' 3 -DR. KERR: I must'say that what I have seen up to L 4-now would-lead me to believe that the two parties involved, L 5 which I have to' assume include a number of competent [ 6 engineers,'could switch. sides.and argue the other-side with 7-equal conviction. 8 DR. LEWIS: Only lawyers could do that. ~ 9 DR. KERR: There is so much ambiguity in the way '10 the definition'is applied. And we aren't, after all, 11 talking about reliability. That's not part of the problem. 12 We are talking about diversity which'is itself ambiguous. 13 And, well-- 14 MR. STALTER: And, Dr. Kerr, I think from our 15 standpoint that really is the bottom line. The only reason 16 we are opposed to putting this' device in is because it's a 17 change to our plant that'we do'not believe adds any 18 reliability to the RPS'or ARI system's capability to insert l 19 rods. 20 The last item that we were asked to talk about was I L 21-what did we see as the ATWS risk improvement. We used the' f 22 Drunswick plant level 1 pRA for the first part of this. Our 23 pre-ATWS rule risk calculated a total core damage frequency 24 of and about 2 1/2 X E~ The ATWS contribution to that was L -5 25 rcnghly 40 percent 1.1 XE C:X Heritage Reporting Corporation (202) 628-4888 j i ____U
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) S g: [- -126 k1 1 Using our model we calculated the post-ATWS rule 2 risk assuming that we ~still had a residual unident'ified 20 3 .g 3: ! percent. common mode failure potential in there and. reduced .i (- 4-core damage. frequency to 2.39 and the ATWS contribution to l 5- '1.02, still approximately 40 percent of core damage .6 frequency. E 71 We then looked at it and said, well, what if we. 8 could getfrid of'all common mode failures. And obviously L 9 addressing just the.Rosemount analog trip unit would not do p 10 that.. There's lots of other components, primarily the t-11 Lmechanical portion remaining. I 12 But'if we could eliminate alluthe common mode n .(k 13 . failure, then we would get a total CD'F of<237 and our ATWS 14 contribution to drop to 1XE-5, again, round numbers still p '15 about 40' percent. 116 The conclusion that we reached from this was that 17 we reduced core damage frequency'with a system that-we have 18 in place by about 3.2 percent, and if we could eliminate all "19 the potential for common mode failure in all systems of the ~~ 20 ATWS-required modifications, we would reduce CDF an 21 additional .8 percent. 22 We asked other plants out there as part of our 23 survey how much reduction they had gotten. The actual I '24 numbers varied from plant to plant, as you would expect. 25 But in general, we were seeing a 10 percent or less effect i Heritage Reporting Corporation (202) 628-4888 l D
.q. k 127 1 of the ATWS modifications on total core damage frequency 2 numbers. l 3 MR. DAVIS: A couple of questions, Dr. Kerr.- I 4 DR. KERR: Certainly. 5 MR. DAVIS: I think that the real concern here is 6 not so much the ATWS contribution to core damage frequency, 7 but the ATWS contribution to public risk. And that's a. I .I 8 totally different number because ATWS events typically 9 produce the h i g'.le s t public consequences because of the 10 threat to the containment. 11 So I think that's a perspective that's not here 12 that would change maybe some of the conclusions here, (q,j-13 The other thlng is I'm familiar with the Brunswick 14 PRA and'I don't recognize these numbers unless you are 15 talking only about internal event. 16 MR. STALTER: That's correct. This is just 17 internal events. 18 MR. DAVIS: At that particular plant, external 19 events dominate the core damage, and, in fact, there's a 20 seismic ATWS that is a substantial contributor. So that 21 would be a different perspective also. 22 MR. STALTER: Right. Yes, it would be. 23 MR. DAVIS: Thank you. 24 MR. STALTER: That concludes our presentation, 25 unless there are further questions. rs Heritage Reporting Corporation (202) 628-4888
.~,7 --- 7, so i F i ~ fy 128 ~1~ DR. KERR: I see no further questions. 2 .Thank_you sir. i ~3. _.That1 brings us to_ combustion engineering. .4' MR. WILLIAMS: I'm-Dan Williams. I'm a member of 5 the1 Steering Committee of the Combustion Engineering Owners 6 Group. 7 About three years'ago, almost three years ago, 8 NRC' accepted the' diverse scram system, diverse turbine trip 9 designs'for CEfplants, and the emergency feedwater 10. actuation. system designs for pre-Arkansas plants. 11 Since that time, the CE plant activity in the area 1:2 of ATWS has been plant specific. That is, non-owners group.. l 13 One caveat on that-is that three of those newer plants have 14'- cooperated in the resolution of the diversity issue for-the 15 emergency feedwater actuation system. 16 There's been significant movement in that area the 17L last few months and it looks like it's near resolution 18 within I would say the next two to three months unless 19 there's-- .20 DR. KERR: What was the diversity issue in that 21 situation? L-22 MR. WILLIAMS: The basic unique aspect of the six 23 CE plants that were involved, three of which are cooperating 24 in addressing the issue, has to do with the fact that they 25 share similar or the same equipment in the electronics that Heritage Reporting Corporation (202) 628-4888 _____j
8 3 ~ d 1 ] 7 i ] d D -...,d 129-ew d f 'l Strip'the. plant and the electronics that actuate emergency 2-feedwater. 3' ..The same bistable, the same physical-bistable, and o- .f 4-the same logic' matrix--the different physical logic matrix ! but'this same piece of equipment. The same physical 6 ' bistable that both' trips the. plant and actuates emergency 7f feedwater. 'That was not true for the older CE-plants. 8 That has been an exemption request that you heard ~ 9 earlier denied, Ton the basis of cost benefit and 10 contribution to'thes reduction of the risk of adding these 11 additional systems. Arguments have been made regarding the .12 increase in; risk from, as I think I heard it characterized, -q .s (j; l'3 . hanging non-safety systems on safety equipment. But right m 14 now we are'trying to find some middle ground and'there does 15-appear to be some progress toward that in the last few 16 weeks. 17. We do not have information--we are not cognizant. 18 we being CE Owners Group, of individual-plant implementation i 19 status or licensing activity. 20 And really because it has not been an owners group 21-activity for about three years. I have very little to say. 22 In fact, that's about all I've got to say. 23 DR. KERR: What is your estimated schedule on the 24 basis of this--for those that are cooperating? 25 MR. WILLIAMS: Those three plants? Heritage Reporting Corporation l (202) 628-4888
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. /~N V, 130 1 DR. KERR: Yes. 2 MR. WILLIAMS: I would anticipate that there will 3 either be a resolution or a deadlock that will lead to some 4 formal action in the next two to three months. And at this 5 point it looks more like a resolution. The latest 6 information I have on the diversity issue so that we can 7 proceed with implementation. 8 DR. KERR: And once you proceeded, at what point 9 would you expect the equipment and training and whatever to 10 be in place and operable? 11 MR. WILLIAMS: I don't know. That's going to be 12 at three different plants on three different schedules. And in .\\ ) 13 it will depend some on what the resolution turns out to be. 14 Whether it's a-- 15 DR. KERR: And is it likely to be one year, ten 16 years? 17 MR. WILLIAMS: Oh, I think closer to the one. 18 That kind of time frame. 19 MR. BARNES: Excuse me. Dr. Kerr? I can 20 probably answer that, if you would? 21 DR. KERR: Would you identify yourself please, 22 sir?- 23 MR. BARNES: I'm Richard Barnes. I'm with 24 Arkansas Power and Light. And deal with ANO 2. One of 25 these six units that's having this current difficulty. Heritage Reporting Corporation (202) 628-4888 i l 1
(~. 'v ' 131 1. L 1 We've essentially split the diverse scram system 2 issue in the diverse turbine trip out.of--and we are 3 currently resolving--proceeding with designs along that. So 4 we'll have the diverse scram system in place probably--I i 5 think the last one to go in is out in California sometime in 6 late '91 I believe. I'm not real sure on that. 7 MR. WILLIAMS: That assumes the resolution we are 8 anticipating. -9 MR. BARNES: Well, no. That's on the diverse 10 scram system. 11 MR. WILLIAMS: Oh, I'm sorry. 12 MR. BARNES: The issue that we are currently t( ) ' 13 negotiating with the staff deals with the AMSAC issue and 14 that, you know, is highly dependent upon ongoing 15 negotiations right now. 16 So a certain amount of our analysis we've done 17 shows that about 98 percent of the achievable ATWS risk 18 reduction is accomplished with the reserve scram system. 19 And we are talking about the remaining less than 2 percent 20 of the total risk improvement available. 21 DR. KERR: Thank you. 22 Any further questions? 23 Thank you, Mr. Williams. 24 That brings ue to the end of our planned and 25 formal agenda. And I think for the need of any further s Heritage Reporting Corporation (202) 628-4888
1 -,I. 132 1 recording of this session. 2 Are there any final comments that the staff would 1 3 like to make? l ? '4 MR. NEWBERRY: No, sir. I think you've got a very 5 good feel for the open issues and what the different views 1. 6 are. 7 DR. KERR: Mr. Lipinski? 8 MR. LIPINSKI: I have one question for the staff. 9 If I were or the Owners Group and'I went to 10 Rosemount and I said, "Please repackage your product such .11 that the card is in the same case." Would that be 12 acceptable to the staff?. As having the required diversity A 'q_). 13 such as the sensor and the card are in the same case? 14 MR. MAUCK: I guess what do you mean by 15 repackaged? HR. LIPINSKI: Take that card. Put it in the same 16 17 case with the sensor, because that pressure sensor meets 18 delayed point. Terminates in a case, those lines go off-- 19 MR. MAUCK: No. .\\ 20 MR. LIPINSKI: Take that card, put it in that same 21 case. Would that be your definition of a sensor then? 22 MR. MAUCK: The intent of the rule, I believe, for 23 allowing non-diversity among sensors was because of the cost 24 of putting in new sensors and being able to use the same 25 sensors in the trip system, i I Heritage Reporting Corporation (202) 628-4888
,cs V) - A 133 1 MR. LIPINSKI: No, you are missing-- 2 MR. MAUCK: So you are trying to cut a fine line 3 here. I 4 MR. LIPINSKI: No, I'm not trying to cut a fine 5 line. I'm trying to decide whether if I were to try to 6 respond to your request, I went to Rosemount and said, " Hey, i 7 please repackage this because I've got a problem with the 1 8 NRC. Put the card in the same vackage with the sensor 9 output." Would I have satisfied your needs saying that now 10 diverse-- 11 MR. MAUCK: No, it's not diverse. 12 MR. LIPINSKI: It's not diverse-- ()' 13 MR. MAUCK: It doesn't have to be because it's a 14 sensor. 15 MR. LIPINSKI: It meets the definition of the l 1 16 rule. The fact that the card is now in that box that's 17 called a sensor output. 18 MR. MAUCK: Well, I guess it would be very 19 difficult to get Rosemount to repackage that card, to be 20 able to put it in the sensor case. 21 MR. LIPINSKI: Whatever I offer them, $100,000-- 22 they are going to be happy to do--it may cost me $100,000 a 23 unit, but I'll get them from Rosemount. Does that meet your 24 requirements? 25 MR. MAUCK: Well, if the card was already in the Heritage Reporting Corporation (202) 628-4888 t-___- - - _ _.-__
l. i 4 -O. .k/ 134 1 transmitter housing, yes.. If that thing is already sitting L 2 there and it's working in the plant and it's used in the 3 trip system. 4 DR. LEWIS: If he wasn't recording, I'd give you i 5 the correlation to-- l 6 MR. MAUCK: Well-- I 7 DR. LEWIS: A story along the same lines. 8 MR. MAUCK: If you read the ATWS rule, it says you 9 can utilize the same sensors. 10 DR. LEWIS: Okay. I think I've made my point. 11 DR. KERR: Any further questions? 12 Okay. No more recording needed. O 13 (Whereevee. the reeeraea vertiee er the 14 proceedings were concluded.) 15 16 17 18 19 20 21 22 23 24 25 O. Heritage Reporting Corporation (202) 628-4888
-- y l l j y h-1 CERTIFICATE j 2 i 3 '~ This is to certify that the attached proceedings before the 4 United States Nuclear Regulatory Commission in the matter 5 of: 6 Name: ACRS Subcommittee on Instrumentation and Control Systems 7 l 8 Docket Number: l 9 Place: Bethesda, MD 10 Date: April 21, 1989 11 were held as herein appears, and that this is the original 12 transcript thereof for the file of the United States Nuclear 13 Regulatory Commission taken stenographically by me and, Q-14 thereafter reduced to erge-rieine hv me or ender the 15 direction of the court reporting company, and that the 16 transcript is a true and accurate record of the foregoing 17 proceedings. 18 /s/ GW /MPV 19 (Signature typed) : 20 Official Reporter 21 Heritage Reporting Corporation 22 23 24 25 O. Heritage Reporting Corporation (202) 628-4888
l 10 l WESTINGHOUSE OWNERS GROUP PRESENTATION TO ACRS I&C SUBCOMMITTEE l O ATWS RULE IMPLEMENTATION APRIL 21, 1989 l l' ROGER NEWTON, CHAIRMAN WESTINGHOUSE OWNERS GROUP MELITA OSBORNE WESTINGHOUSE NUCLEAR SAFETY i o
a I O A1WS RULE AND WOG RESPONSE ) JULY 1984 RULE ISSUED. JUNE 1985 WOG GENERIC AMSAC DESIGNS SUBMITTED (WCAP-10858) JULY 1986 NRC SER FOR AMSAC FEBRUARY 1987 WOG INFORMATION ON ONE ITEM FROM SER JUNE 1987 NRC REQUEST FOR INFORMATION ON FUEL MANAGEMENT AUGUST 1987 WCAP-10858 REY. 1 ANSAC ADDITIONAL ITEMS l; MARCH 1989 RESPONSE TO NRC 6-87 REQUEST WCAP-11993 LO 0104N:MPO 4/19/89
L I (I WOG ATWS RULE PROGRAMS GOALS S PROVIDE GENERIC MEANS FOR ADDRESSING THE ATWS RULE 8 ALLOW. UTILITY FLEXIBILITY IN RULE IMPLEMENTATION O 1. DEVELOP AMSAC, DESIGN (S): WCAP-10858 AMSAC GENERIC DESIGN PACKAGE APPROVED JULY 1986. WCAP-10858, REV. 1 ADDITIONAL ITEMS AUGUST 1987 2. RESPONSE TO JUNE 1987 NRC LETTER WCAP-11993 ASSESSMENT OF COMPLIANCE WITH ATWS RULE BASIS FOR WESTINGHOUSE PWRS MARCH 1989 0 0104N:NPD 4/19/89
(2) WOG ATWS RULE PROGRAM ) 1. AMSAC FUNCTIONAL DESIGN -- WCAP-10858. REV. 1 8 WOG DEVELOPED THREE FUNCTIONAL DESIGNS ALLOWS UTILITY TO SELECT DESIGN BEST SUITED FOR PLANT EACH DESIGN MEETS THE REQUIREMENTS OF 10CFR50.62 APPROVED BY THE NRC () 8 .WOG AMSAC ACTUATION LOGICS LOGIC 1 - LOW STEAM GENERATOR LEVEL LOGIC 2 - LOW FEEDWATER FLOW LOGIC 3 - MAIN FEEDWATER PUMP STATUS OR MAIN FEEDWATER VALVE CLOSURE 1 9 IMPLEMENTATION OF APPROVED FUNCTIONAL DESIGN ALSO REQUIRES PLANT SPECIFIC NRC APPROVAL O 01MN:MPO-4/19/89
WOG ATWS RULE PROGRAM AMSAC FUNCTIONAL DESIGN SUW4ARY 0 WOG GENERIC DESIGN APPROVED 4 TWO KEY ELEMENTS GENERICALLY ADDRESSED BY WOG O 4 12 KEY ELEMENTS REVIEWED FOR PLANT SPECIFIC IMPLEMENTATION l O oz 'r "a'-
l1 WOG ATWS RULE PROGRAM 2. ASSESSMENT AND RESPONSE - WCAP-11993 PURPOSE .8 ADDRESS FUEL MANAGEMENT QUESTIONS IN CONTEXT OF INTEGRATED EFFECTS ON ATWS RESPONSE MECHANICS OF THE PROGRAM 4 REVIEW RISK BASIS OF ATWS RULE, AND HISTORY I LEADING UP TO ATWS RULE {} e REVIEW SECY-83-293 MODEL ASSUMPTIONS IN LIGHT OF CURRENT INDUSTRY EXPERIENCE 9 CONSTRUCT AN APPROPRIATE CORE DAMAGE FREQUENCY MODEL (EVENT TREE): CONSISTENT WITH ATWS RULE BASIS NORE SPECIFIC TO WESTINGHOUSE PWRS AND AMSAC COMPATIBLE WITH SEVERE ACCIDENT POLICY STATEMENT O 01044 "90 4/19/89
nW
- O-WOG ATWS RULE PROGRAM RESULTS/ CONCLUSIONS L
ASSESSMENT AND RESPONSE -- WCAP-11991 0 PROGRAM SHOWED CONTINUED ACCEPTABILITY OF ATWS CORE DAMAGE FREQUENCY (CDF) FOR ' WESTINGHOUSE PLANTS'AS A CLASS, GIVEN INSTALLATION OF AMSAC - SECY-83-293 TARGET IS MET. 4 ALTHOUGH AMSAC IS REQUIRED TO MEET THE TARGET, AMSAC UNAVAILABILITY IS NOT A SIGNIFICANT CONTRIBUTOR TO'CDF 4 FUEL MANAGEMENT HAS A SMALL TO INSIGNIFICANT EFFECT ON CDF, DEPENDING ON AVAILABILITY OF PRESSURE RELIEF - SECY TARGET IS MET. O PROGRAM MODEL IS COMPATIBLE WITH IPE L o j 0104W:@ 0 4/19/89
O-AMSAC IMPLEMENTATION STATUS 8 -WOG SURVEY - APRIL 1989 26 SITES 43 UNITS S PLANT. SPECIFIC NRC APPROVAL 22 APPROVED 3 PENDING 1 NOT YET SUBMITTED Q 0 INSTALLATION 22 INSTALLED 7 TO BE INSTALLED SHORTLY OR AT KEXT REFUELING 14 NOT INSTALLED YET 0 OPERATING EXPERIENCE 4-6 MONTHS PER PLANT AVERAGE 0-18 MONTHS RANGE NO PROBLEMS TO DATE O 0104N:MP0-4/19/89
O AMSAC IMPLEMENTATION STATUS 8 LoorcS SELECTED 23 Low SG LEVEL 12 Low MAIN FW FLOW 6 MAIN FW PUMP TRIP /YALVE CLOSURE IMPLEMENTATION 11 WESTINGHOUSE 5 UTILITY DESIGN 8 OTHER SUPPLIERS () 0 WOG GENERIC DESIGN ALLOWS FLEXIBILITY IN LOGIC AND IMPLEMENTATION 0 NRC HAS APPROVED UTILITY IMPLEMENTATIONS 0104N:MPO 4/19/89
l l l l \\ LO L AMSAC IMPLEMENTATION STATUS L 4 OPEN ITEMS (BASED ON SURVEY) l 1 TECH SPECS (GENERIC) CONTROL Room HUMAN FACTORS REVIEW 4 WOG GENERIC RESPONSE ON TECH SPECS O l O 0104N:MPO 4/19/89
w 3h ATWS RULE IMPLEMENTATION
SUMMARY
/CONCLUSIDHS m
8 ' RULE REQUIRES AMSAC n j 0-NRC HAS APPROVED GENERIC WOG FUNCTIONAL DESIGNS FOR AMSAC 9 UTILITY IMPLEMENTATION REFERENCES THE WOG t DESIGN O 4 NRC HAS APPROVED PLANT SPECIFIC IMPLEMENTATIONS 't WOG ASSESSMENT OF SECY-83-293 BASES SHOWS WESTINGHOUSE CLASS OF PLANTS CONTINUES TO SATISFY BASIS OF RULE WITH AMSAC WOG/ WESTINGHOUSE PLANTS ARE SUCCESSFULLY IMPLEMENTING THE REQUIREMENTS OF THE ATWS RULE. ) C'f4W:=IPO 4/19/89
[fC ~ O fl TTE RULE (10 CFR 50.62) IMPLEMENTATION CHRONOLOGICAL BACKGROUND ATWS RULE PUBLISHED 6/84 QA GUIDANCE FOR ATWS EQUIPMENT 4/85 (G.L. 85-06) NRC REVIEW EFFORT START 5/85 (MULT!-PLANT ACTION A-20 ESTABLISHED) p. ?* OWNERS GROUP SUBMIT GENERIC DESIGN -Q CEOG CEN-315 9/85 BWOG BaW 47-1159091 10/85 WOG WCAP-10858 10/85 BWROG NEDE-31096-P 1/86 NRC STAFF ACCEPTED GENERIC DESIGN WOG 7/86 BWROG 10/86 BWOG 6/88 NR6 STAFF REJECTED CEOG REPORT, REGARDING 8/86 DIVERSp0FAFWACTUATION 1 3-INSPECTION GUIDANCE ISSUES (TI 2500/20) 2/87 NRC STAFF PLANT SPECIFIC REVIEWS 1/87 -- PRESENT 82 SERS COMPLETED O 30 PLANTS INSPECTED
1 1 2 2 S 99 T N LL1 1 A LP9 7 53 LI M9R PWI 1 O ST NLL0 A LP9 2 0 43 LI M9 1 PWI 1 S S T U NLL9 TA A LP8 21 6 33 T LI M9 1 S PWI 1 l OE. h iN S E T D N L 6 2 6 0 3 6 A P 3 3 3 2 IF L M P l I I ) C A SM ) 5 A 5 ( N L T O A K T C I T O M CL T T E ( C T EO J R A S I NT S ) Y ) ,4-PI N T N 5 S 8 O N O 1 I M L RDC A I T0 L T L A A ) R Q P A A R T -7 P I G T C O 3 MEL E I O S T UT S T T ( L PAY U I ( E A NB O M S T T RRD H T CR N O I EN G S N A E A T CTA N W A S V L T L MI P ( ELT O I RAS T A P AD R S W W E E B W C B rL l
f"3 g OPEN ISSUES AND NRC STAFF POSITION -f (1) BWR PLANTS INSTRUMENT DIVERSITY MANY BWR PLANTS HAVE INSTALLED SAME TYPE OF ANALOG 'RANSMITTER TRIP UNITS (ATTU) FOR BOTH THE RTS AND THE ARI SYSTEM. THIS DOES NOT SATISFY THE ATWS RULE DIVERSITY REQUIREMENT. BWROG ARGUMENTS: (1) THE ATTU IN THE RTS IS DE-ENERGIZED TO FUNCTION WHILE THE ATTU IN THE ARI SYSTEM IS ENERGIZED TO I FUNCTION O a (2) OTHER PARAMETERS AND MEANS ARE AVAILABLE TO TRIP THE REACTOR THROUGH THE RTS SHOULD THE ATTU FAIL DUE TO COMMON MODE FAILURE (3) COST / BENEFIT DOES NOT JUSTIFY REPLACING THESE INSTRUMENTS THE STAFF POSITION: TN,ENERGIZATION IS DEPENDENT ON A SWITCH SETTING 0N THE ATTU CIRCUIT BOARD. THE CIRCUIT BOARDS FOR THE RTS AND ARI SYSTEM ARE IDENTICAL. THE STAFF POSITION IS THAT HARDWARE / COMPONENT DIVERSITY IS REQUIRED TO PREVENT COMMON MODE FAILURE WHICH COULD CAUSE SIMULTANE0US DISABLING OF THE RTS AND THE ARI SYSTEM. THE LICENSEES ARE REQUIRED TO INSTALL DIVERSE HARDWARE.
i .O .', ;) 1- - ' OPE (ISSUESANDNRCSTAFFPOSITION (2) NEWER CE PLANT AFW ACTUATION DIVERSITY SOME NEWER CE PLANTS AFW ACTUATION USES SAME TYPE OF { COMPONENTS WHICH WERE USED IN THE EXISTING RTS. THIS DOES NOT SATISFY THE ATWS RULE DIVERSITY REQUIREMENT CEOG ARGUMENTS -O THREE UTILITIES SUBMITTED EXEMPTION REQUESTS. THE MAIN ARGUMENT IS THAT TO INSTALL A DIVERSE AMSAC WILL ONLY l HAVE MARGINAL SAFETY BENEFIT AND IS Il0T COST EFFECTIVE. THE STAFF POSITION: THE COST / BENEFIT ARGUMENT HAD BEEN CONSIDERED DURING RULE MAKING PROCESS. THE NRC STAFF CONCLUDED THEN THAT T K SAFETY BENEFITS WERE JUSTIFIED TO REQUIRE THE DEBI6N OF AMSAC TO BE DIVERSE AND INDEPENDENT FROM THE EXISTING RTS. O l i
O i MEANING OF " INDEPENDENCE" ATWS RULE GUIDANCE STATES: LOGIC AND ACTUATION DEVICE POWER MUST BE FROM AN INSTRUMENT POWER SUPPLY INDEPENDENT FROM THE POWER SUPPLIES FOR THE EXISTING REACTOR TRIP SYSTEM. 1 EXISTING RTS SENSOR AND INSTRUMENT CHANNEL POWER f 1 ~Q MAY BE USED PROVIDED THE POSSIBILITY OF COMMON MODE FAILURE IS PREVENTED THE STAFF POSITION: THE INDEPENDENT NON-1E POWER IS THE PREFERRED DESIGN. THE POWER SUPPLIES FOR DSS AND AMSAC ARE FROM NON-CLASS IE POWER WITH NON-1E BATTERY BACKUP. THE SHARED'1E POWER IS ACCEPTABLE IF DSS AND AMSAC ARI CLASS IE SYSTEMS. A FMEA IS REQUIRED TO DEMONSTRATE THAT THE POSSIBILITY OF COMMON MODE I FAILURE IS PREVENTED. O L
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<[, [ MEANING 0F " DIVERSITY" THE BASIC PREMISE BEHIND THE ATWS RULE IS TO PREVENT OR MINIMIZE THE C0fm0N MODE FAILURE WHICH SiMULTANE0USLY DISABLES THE REDUNDANT RTS CIRCUITRIES. THE DIVERSITY REQUIRED BY THE ATWS RULE IS HARDWARE OR COMPONENT DIVERSITY, ACCEPTABLE LEVEL OF COMPONENT DIVERSITY CAN BE ACHIEVED IN ACCORDANCE WITH COMBINATION OF ALLOWABLE METHODS SUCH AS o THE USE OF COMPONENTS FROM DIFFERENT MANUFACTURER o FUNCTIONAL CAPABILITY j THE ATWS RULE GUIDANCE STATES THAT EQUIPMEllT DIVERSITY IS REQUIRED FROM SENSOR OUTPUT TO AND INCLUDING THE COMPONENTS USED TO INTERRUPT CONTROL R0D POWER FOR DIVERSE SCRAM SYSTEM, AND FROM SENSOR OUTPUT T0, BUT NOT INCLUDING, THE FINAL ACTUATION DEVICE FOR MITIGATION SYSTEMS. IDENTICAL COMPONENTS USED IN BOTH THE EXISTING RTS AND THE DIVERSE SCRAM SYSTEM OR MITIGATING SYSTEMS ARE SUBJECT TO POTENTIAL COMMON MODE FAILURES, AND THEREFORE ARE NOT ACCEPTABLE. I O l ____m
age No. 1 4 17/99 i RlLE IffLEPENTATION STATUS SY NOSS DESIGN MfEftAL ELECTRI fr7 ARI SLIC RESION INSP PLANTS IppL IPPL IPFL CopF i SIS FtOCK POINT 1 1 EXEPPT I EXEfFT I YES I 3 I l
- 1. SRotels PERRY 1 i
YES I RESTART I RESTART I 2 I I I SROISdB FERRY 2 I YES 1 06/99 I YES I 2 I I I SROISS FERRY 3 I YES I RESTART I RESTART I 2 l .I I SRL9dStf!CK 1 I YES I YES I YES I 2 I YES I I SRL#dStf!CK 2 I YES I YES l YES I 2 I YES I 'I-CLINTENd i I YES I YES I YES I 3 I YES I I COOPER 1 I YES I YES I YES I 4 l 1 I DRESDEN 2 1 YES I YES I YES I 3 I YES l 1 DRESDEN 3 I YES I YES I YES I 3 I YES I i DUAfE ARNELD I YES I YES I YES I 3 I YEC 1 i FERRI 2 I YES I YES I 09/99 8 3 I YES i i FITZPATRICK 1 1 YES I YES I YES I '1 l i I GRAfG SLLF 1 I YES I YES I YES I 2 i YES I I HATCH 1 1 YES I YES I YES I 2 1 cc I I HATCN 2 I YES I YES I YES I 2 1 I i ! MOPE CREEK 1-I YES I YES I YES I 1 I YW l i LA SALLE 1 I YES I YES I YES I 3 i YSS I Q LA SALLE 2 I YES I YES I YES I 3 I YES I I *IfERICK 1 I YES I YES I YES I 1 I I I .!LLSTOfE 1 I YES I YES I YES I 1 1 YES 1 1 MONTICELLO 1 I YES I YES I YES I 3 1 I i NINE MILE POINT 1 I YES I YES I YES I 1 I YES I I HINE MILE POINT 2 I YES I YES I YES X 1 I YES I I OYSTER CREEK 1 I YES I YES I YES l 1 I YES I I PEACH SOTTOM 2 I YES I 06/99 I YES I 1 1 1 1 PEACH SOTTOM 3 I YES I YES I YES X 1 1 I I PERRY 1-I YES I YES I YES 1 3 I YES ! PILGRIM i YES I YES I YES I 1 1 I i QUAD CITIES 1 1 YES I YES I YES I 3 I YES 1 i GUAD CITIES 2 I YES I YES I YES I 3 I YES I I RIVER SEND & 1 YES I YES I YES I 4 I YES I I SHOREHAR 1 I YES I YES I YES I 1 1 1 1 a m m4Af444 1 I YES I YES I YES I 1 1 I I e m m4ApS44 2 I YSS i YES I YES I 1 1 I I VERMONT YAfSEE 1 I YES I YES I YES I 1 I i i ISP 2 I YES I YES I YES I 5 I YES I O
No. 1 '12/89 ATM RLE.E IlrLEPENTATION STATUS SY NESS DESIGN n IESTIN N Sj APWAC RESION INSP PLANTS f' IlrL COPP i MAVER VALLEY 1 I YES I 1 I YES I I SEAVER VALLEY 2 1 7/99 1 1 1 I I SRAIDWOOD 1 1 12/90 1 3 I I I SRAIDWOOD 2 1 12/91 1 3 I I I SYREM 1 I 4/90 1 3 I I I SYRON 2 1 10/90 1 3 I I .I CALLAWAY 1 1 6/39 1 3 1 l I CATAWA 1' I YES I 2 I I I CATAleA 2 1-5/39 I 2 I I I CENtAPO E PEAtC 1 1 6/39 I 4 I I I COMAfCE PEAIC 2 I F. L. I 4 I I I COEBC 1 1 7/39 1 3 I I I ' CtXBC 2 1 12/99 1 3 I I I DIASLO CANYON 1 1 10/39 1 5 I I i DIASLO CANYtNd 2 I YES I 5 I YES I I.FARLEY 1 I YES I 2 l YES I ~ 1 FARLEY 2 I YES I 2 I YES I I 819944 1 I YES I 1 I l 1 HADDAM DECK 1 1 EXEFFT I 1 1 I . O S -ARON aaRRIS 1 i vES i 2 i i NDIAN POINT 2 1 10/39 1 1 I I I INDIAN POINT 3 I YES I 1 I I I KEWAUNEE 1 I YES I 3 1 1 1 MCGUIRE 1 1 YES I 2 I I i MCGUIRE 2 I YES I 2 1 1 1 MILLSTONE 3 1 6/89 1 1 1 I ! NORTH ANNA 1 1 5/89 2 I I I NORTH ANNA 2 I YES I 2 I I I POINT BEACH 1 1 5/90 1 3 I I I POINT BEACH 2 1 10/89 1 3 I i i PRAIRIE ISLAND 1 1 11/89 1 3 I I -I PRAIRIE ISLAND 2 I YES I 3 I I I ROSINSON 2 I YES I 2 l I I SALEN 1 I YES I 1 1 I i SALEM 2 I YES 1 1 1 I I SAN ONOFRE 1 1 12/99 I 5 I I I SEASROOIC 1 1 9/90 1 1 1 I I SEOUDYAH 1 1 4/90 1 2 I I I SEIWOYAH 2 i S/90 1 2 I I I SOUTH TEXAS 1 1 1/90 1 4 I I i StWTH TEXAS 2 i F. L. I 4 I I I St#SER 1 1 YES I 2 I I I MAWtY 1 1 12/99 1 2 I I 1 4/90 1 2 I I OISURRY2 I MAN 1 1 7/99 I 5 I I i-LMICEY POINT 3 1 10/91 1 2 I I I T1ADCEY POINT 4 1 11/92 1 2 I I 1 VOSTLE 1 I YES I 2 1 YES I I VOSTLE 2 I YES I 2 I YES I I MATTS SAR 1 1 F. L. I 2 I I I.
Page No. 2 04/12/89 f AM #41A,3 Ippg,,gPEPfTATICD1 STATUS SY NOSS ZESIm NIN AfWAC f4ESION INSP N 4.* 1991. COPP i MTTS Mft 2 l' = L. I 2 I I I WOLF Cl4EEK 1 l ygg 3 4 g ygg I YAfGEE ftONE 1 1 EXEPPT l 1 g I 1 ZION 1
- tofg, g
3 g I ZION 2 1 3/90 1 3 3 ? ? 'O l l O l _..-_..~.._._...J
No. 1 12/89 AThe IRA.E IWLEPENTATION STATUS SY NOSS DESISM CE ,'[ APWAC DOS RESION IMF PLANTS IPM. IPM. COPF i AfSCANSAS 2 1 11/89 1 11/89 I 4 1 1 1 CALVERT CLIF75 1 I YES I YES I 1 I YES I I CALVERT CLIFFS 2 1 05/89 1 05/09 l 1 I i 1 FORY CALHOLM 1 I YES I YES I 4 I YES I I NAIPE YAPOWE 1 1 06/90 1 06/90 1 1 1 I I MILLSTtBE 2 I YES I YES I 1 1 I I PALISADES 1 1 04/90 1 04/90 1 3 I l 8 PALO VERDE 1 1 06/90 I YES I 5 I I I PALO VERDE 2 1 04/91 1 YES 1 5 I I I PALO VERDE 3 I 09/92 I YES I 5 I I I SAN m 2 I 05/91 1 05/91 1 5 I i ! SAN 13EFRE 3 1 10/91 1 10/91 1 5 I I I ST. LUCIE 1 I 10/91 1 10/91 1 2 I I I ST. LUCIE 2 1 09/90 1 09/90 1 I NATERFORD 3 1 12/99 1 12/89 i ' 2 I I 4 I I I ter 3 I / I / I S I I N O O L_-_
No. 1
- 12/09 ATtm 14A2 IfrLENDITATICD4 STATUS SY NOSS DESIM h
) SW bfgp AfGAC OSS RESION INSP PLANTS e-. IfrL IPPL CopF 1 1 ARKANSAS 1 1 04/90 1 04/90 1 4 I I I CRYSTAL RIVER 3 1 04/90 1 04/90 1 2 I I I DAVIS-SESSE 1 1 05/90 1 05/90 1 3 I I I DCENSE 1 1 09/91 1 09/91 1 2 I I I OctNEE 2 1 01/92 1 01/92 1 2 I I i DCESEE 3 1 05/91 1 05/91 1 2 I I I RAfDE3 WCO 1 1 05/91 1 05/91 1 5 I I I TRI-1 1 12/91 1 12/91 1 1 I k-O O
{ t S ~ K<'cb+ f.L /} xv L EWR THS INTERACTION WITH ATWS CONCERNS: (1) WILL LARGE OSCILLATIONS CAUSE EFFECTIVE POWER INCREASE r DllRING " LOW FLOW-PART POWER" SLCS INJECTION MODE? (2) IF S0, WILL SUPPRESSION POOL TEMPERATURE INCPEASE SIGNIFICANTLY PPIOR TO SHUTD0'et' BY LIQUID CONTROL? (3) WILL OSCILLATIONS ADVERSELY INTERACT WITH E0P? O i ) i
\\ ) O BWROG, GE, EPRI CALCULATIONS 8 CONCLUSIONS t o TRAC-GE-3D LARGE AMPLITUDE SYMMETRIC OSCILLATION CALCULATION o DISCUSSED IN MEETINGS. REPORT DUE IN APRIL. n PEAK AMPLITUDE-200 PERCENT POWER o GE INDICATES N0 SIGNIFICANT, OSCILLATION PRODUCED, POWER INCREASE. (SMALL INCREASE FROM SYSTEM EFFECTS.) (3 o RECENT EPRI PEER REVIEW o CONCLUDE THERE IS NO NEW PROBLEM o NO FURTHER LARGE OSCILLATION CALCULATIONS PLANNED o EPRI IS INVESTIGATING OPERATOR RESPONSE TO ATWS WITH OSCILLATIONS O e L__
q ~ l Q n, BNL CALCULATIDFS e o RAMONA-3B AND EPA o RAMONA NOT.YET ABLE TO EXPLORE LARGE AMPLITUDE OSCILLATIONS. (T-H CODE BREAKDOWN.) O -o EPA HAS BEEN EXPLORING ATWS SCENARIOS o HAVE NOT QUANTIFIED OR SEPARATED EFFECT OF OSCILLATIONS ON THERMAL POWER Q,
f) JBNL CONTINUED) 0 FUTURE PLAhS (ATWS RELATED) RAMONA IMPROVE T-H TO HANDLE LARGE OSCILLATIONS 1 BENCHMARK (LASALLE AND OSKARSHAMN) EXPLOPE LARGE OSCILLATIONS-(PEAK AMPLITUDES, THERMAL EFFECTS) O EPA FURTHER ATWS SCENARIOS AND OTHER CALCULATIONS TO QUANTIFY THERMAL EFFECTS OF LARGE OSCILLATIONS OTHEP. INEL (TRAC-ID) ATWS SCENARIOS AND ORNL (LAPUR) SUPPORT CALCllLATIONS RES REVIEW TEAM
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- D i
.g PWP ATWS MODERAT0P TEMPERATURE COEFFICIENTS 4 STAFF PRESENTATION TO ACRS ISC~ SUBCOMMITTEE MEETING ON ATWS PULE IMPLFPENTATION APRIL 23, 1989 O
I i($)l o STAFF HAD PREVIOUSLY EXPRESSED CONCERN ON. VALIDITY OF EARLIER PWR ATWS ANALYSIS ASSUMPTION ON MODERATOR TEMPERATURE COEFFICIENT BECAUSE OF CHANGES RELATED TO: EXTENDED CYCLES OF 18 AND 24 MONTHS INCREASED DISCHARGE PURNUP LOW LEAKAGE CORE DESIGNS O NEW FUEL DESIGNS MODERATOR TEMPERATURE COEFFICIEtlT (MTC) TECHNICAL SPECIFICATION CHANGE REQUESTS 4 9
1' l
- c4 Q) '
l~ 1 1 i o CONCERN LED-TO LETTER TO PWR OWNERS GROUPS (JUNE 12, 1987) JUSTIFICATION FOR THE CONTINUED APPLICABILITY OR C0FSERVATISM IN ATWS BASIS MTCs DIFFERENCES IN CURRENT MTCs WITil ATWS BASIS MTCs PLANT DATA USED ASSUMPTIONS MADE METHODOLOGY USED TO DERIVE ATWS MTCs .O
OL ~ ( o STAFF MEETINGS WITH OWNERS GROUPS' WOG/E OCTOBER 7, 1987 FEBRUARY 13, 1988 CEOG/CE JANUARY 31, 1988 ' d,, BK0G/B8W FEBPUARY 18, 1988 o MEETING WITH ACPS COMBINED CORE PERFORMANCE AND SCRAM SYSTEMS RELIABILITY SUBCOMMITTEES ON FEBRUARY 19, 1988 O I
.t O. RESULTS FOR'ATWS MTCs (10-5 g gfgf.p) o ATWS ANALYSIS BASIS CURPENT VALUES WOG/1 -8 -10 (STAFF ESTIMATE) CEOG/CE (2750 MWT) -2 - 2.6 (3410 MWT) -6.3 - 5.0 (3800 MWT) -6.8 - 3.7 BWOG/P8W (177 FA) -10.5 -JJ 0 (18 MONTH CYCLE) - 4.3 (24 MONTil CYCLE) o CONCLilSION - THE CURRENT MTC DATA IS CONSISTENT FITil PREVIOUS ATFS P'TC ANALYSIS BASIS FOR ALL PWR PLANT TYPES O
O BWR OWNERS' GROUP 1 ATWS IMPLEMENTATION STATUS O S. D. FLOYD CAROLINA POWER & LIGHT APRIL 21, 1989
- O
4 O BWR OWNERS' GROUP 1 . AGENDA 0 INTRODUCTION S. D. FLOYD 0 ATWS GENERIC REPORT STATUS S. D. FLOYD 0 IMPLEMENTATION PROBLEMS S. D. FLOYD O IMPLEMENTATION STATUS-S. D. FLOYD O 0 EXEMPTIONS /SPECIAL DIFFICULTIES S. D. FLOYD/ W. P. SULLIVAN. O ATWS RISK IMPROVEMENT S. D. FLOYD o
lh AIRS GENERIC REPORT STATUS l 0 LICENSING TOPICAL REPORT SUBMITTED TO NRC DECEMBER 1985 0 SAFETY EVALUATION REPORT ISSUED --- OCTOBER 1986 l 0 APPROVED LTR ISSUED --- FEBRUARY 1987 c l l i LO
O IMPLEMENTATION PROBLEMS 0 NRC REQUEST FOR ADDITIONAL DIVERSITY FOR ANALOG TRANSMITTER TRIP UNITS (ATTU's) IN ALTERNATE ROD INSERTION (ARI) SYSTEM Q 0 NRC REQUEST FOR MODIFICATIONS TO RECIRCULATION PUMP TRIP (RPT) LOGIC O j
i
- O IMPLEMENTATION STATUS l
0 37 TOTAL UNITS SUBJECT TO ATWS RULE O 30 UNITS ESSENTIALLY COMPLETE 17 UNITS TOTALLY COMPLETE 11 UNITS COMPLETE EXCEPT FOR DIVERSITY ISSUE O 2 UNITS COMPLETE EXCEPT FOR DIVERSITY ISSUE AND RPT LOGIC / TESTABILITY 0 7 UNITS INCOMPLETE 6 HAVE DIVERSITY ISSUE O TOTAL OF 19 UNITS NEED RESOLUTION OF DIVERSITY ISSUE O
r O EXEMPTIONS TO ATWS RULE 0-REQUESTED j EQUIVALENCY BASED ON VESSEL DIAMETER' (1 UTILITY) O POTENTIAL DIVERSITY OF ARI ATTU's O (19 UNITS) 4 O I
l LO-ATWS DIVERSITY ISSUE STAFF POSITION: 0 TRIP UNIT IS NOT PART OF THE SENSOR AND THEREFORE REQUIRES DIVERSITY, l O ARI SYSTEM LACKS DIVERSITY AND DOES NOT COMPLY WITH ATWS RULE (ARI AND RTS BOTH USE ROSEMOUNT ATTUs). STAFF PROPOSED RESOLUTION: 3 0 REPLACE ROSEMOUNT ATTU CIRCUIT BOARD WITH AN EQUIVALENT BOARD MANUFACTURED BY A DIFFERENT VENDOR. BWROG POSITION 0 THE TRIP UNIT IS PART OF THE " SENSOR" WHICH IS NOT REQUIRED TO BE DIVERSE BY THE RULE. O ARI SYSTEM MEETS THE DIVERSITY REQUIREMENT OF THE RULE AND MINIMIZES THE POTENTIAL FOR COMMON MODE FAILURE. O STAFF'S PROPOSED RESOLUTION IS NOT NECESSARY TO MEET THE RULE. OFFERS LITTLE OR NO IMPROVEMENT O IN CDF.
- O ALTERNATE ROD INJECTION (ARD DIVERSITY ISSUE O
W. P. SULLIVAN GENERAL ELECTRIC l. i
1 O i RECOMMENDATION OF THE ATWS TASK FORCE (SECY 83-293 ENCLOSURE "D") THELTRIP PORTION OF THE SENSn* SYSTEM CONSISTS OF BISTABLES THAT SIGNAL-AN OUT-0F-TOLERANCE CONDITION. THIS PORTION OF THE SYSTEM IS ' VULNERABLE TO BISTABLE CALIBRATION ERRORS AND LIKE COMPONENT COMON CAUSE FAILURES.
- HOWEVER, CONTINUOUS MONITORING 0F THE SENS0R OUTPUT, AND THE FREQUENT TESTING OF THE TRIP VALUES PROVIDE A GOOD CHANCE OF DISCOVERY 0F SUCH COMON CAUSE Q
PROBLEMS. . THOUGH DIFFERENCES EXIST IN THE LEVEL OF P.EDUNDANCY AND LOGIC STRUCTURE, THESE 0NLY INFLUENCE THE INDEPENDENT FAILURE CONTRIBUTION WHICH DOES NOT CONTRIBUTE SIGNIFICANTLY TO THE OVERALL RPS UNAVAILABILITY. THEREFORE, FOR THE PURPOSES OF THIS ANALYSIS, THE SENSOR PORTION OF THE RTS WILL BE IGNORED. "THE SENSORS NEED NOT BE OF A DIVERSE DESIGN OR MANUFACTURER." l-O - STATEMENT OF CONSIDERATIONS, FINAL ATWS RULE. 49 F.R. 26042 1
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01 RESULTS FROM RISK ASSESSMENT LOSS OF FEEDWATER EVENT l 1 0 THREE SEPARATE SETS OF WATER LEVEL TRIP UNITS 1 MINIMUM OF SIX INDIVIDUAL TRIP UNIT FAILURES 0 OPERATOR HAS.AT LEAST 15 MINUTES TO INITIATE MANUAL CONTROL ROD INSERTION C-DIVERSE REACTOR WATER LEVEL INDICATION AND APRM DOWNSCALE ALARM PROVIDED EPG REV. 4 PROVIDES APPROPRIATE OPERATOR GUIDELINES 0 PROBABILITY OF COMPLETE LOSS OF LEVEL INDICATION AND ASSOCIATED SCRAM { 2.3 E-08/ REACTOR-YEAR O )
i SHOULD PROPOSED STAFF RESOLUTION BE IMPLEMENTED? PEDS 1. SOME SMALL REDUCTION IN COMMON MODE FAILURES RESULTING FROM FABRICATION PROCESS. cons 1. SUBSTITUTE UNPROVEN EQUIPMENT FOR PROVEN, (; HIGHLY RELIABLE EQUIPMENT. 2. BATCH PRODUCED EQUIPMENT HAS NO QUALITY HISTORY. 3. RAISES POTENTIAL FOR COMMON MODE FAILURE BY COMPLICATING MAINTENANCE AND PROCUREMENT PROCEDURES. 4. HIGH COST ($170K PER REACTOR) VERSUS NEGLIGIBLE SAFETY IMPROVEMENT. [3> 5. ESTABLISHES A DIVERSITY DEFINITION INCONSISTENT WITH RULE. i
DIVERSITY ISSUE SU M RY p 0 TRIP UNIT IS PART OF SENSOR AND DOES NOT REQUIRE DIVERSITY 0. " DIVERSITY" IS NOT LIMITED TO " EQUIPMENT DIVERSITY" BY THE ATWS RULE RULE-STATES " DIVERSITY" STATEMENT OF CONSIDERATIONS STATES EQUIPMENT DIVERSITY WHERE REASONABLE AND PRACTICABLE " STAFF POSITION ON DIVERSITY REQUIREMENTS" ALLOWS COMBINATION OF ALLOWABLE METHODS WHERE TOTAL HARDWARE DIVERSITY IS DIFFICULT TO ACHIEVE RECENT STAFF DECISIONS REQUIRE TOTAL I HARDWARE DIVERSITY REGARDLESS OF DIFFICULTY, COST OR BENEFIT FABRICATION DIVERSITY FOR THE ROSEMOUNT ATTUs PROVIDES NEGLIGIBLE SAFETY IMPROVEMENT 0-CURRENT DESIGN MEETS BOTH LANGUAGE AND INTENT OF ATWS RULE
L 1[1 ATWS RISK IMPROVEMENT RRUNSWICK PLANT PRA CF PRE ATWS RULE RISK i TOTAL'CDF 2.47 E-5 = ATWS CONTRIBUTION = 1.1 E-5 i 'O POST ATWS RULE RISK (ASSUMES 20% COMMON MODE FAILURE REMAINS) TOTAL CDF 2.39 E-5 = ATWS CONTRIBUTION = 1.02 E-5 C3 0 POST ATWS RULE RISK (0% COMMON MODE FAILURE) TOTAL CDF 2.37 E-5 = ATWS CONTRIBUTION = 1.00 E-5 0 CONCLUSION ATWS RULE REDUCED CDF BY 3.2% TOTAL ELIMINATION OF COMMON MODE FAILURE WOULD REDUCE CDF AN ADDITIONAL 0.8% INDUSTRY BWR PRAs 0 EFFECT OF ATWS MODS VARIES FROM PLANT TO PLANT O. 0 10% OR LESS EFFECT OF MODS ON TOTAL CDF .J}}