ML20038C399
| ML20038C399 | |
| Person / Time | |
|---|---|
| Issue date: | 11/24/1981 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| Shared Package | |
| ML20038C400 | List: |
| References | |
| REF-10CFR9.7, TASK-A-49, TASK-OR NUDOCS 8112100568 | |
| Download: ML20038C399 (95) | |
Text
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PDIL NCCE.AR REGULATORY COMMISSICN O8 r
i COMMISSION MEETING
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1 In h h Cf PUBLIC MEETING BRIEFING ON PRESSURIZED THERMAI, SHOCK r
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UNITED STATES OF AMERICA 2
NUCLEAR REGULATORI COMMISSION 3
4 BRIEFING ON PRESSURIZED THERHAL SHOCK
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PUBLIC NEETING 7
8 Nuclear Regulatory Commission Room 1130 9
1717 H Street, N. W.
Washington, D.
C.
10 Tuesday, November 24, 1981 11 12 The Commission met at 1:30 p.m.,
pursuant to 13 notice.
I 14 BEFORE:
15 NUNZIO PALLADINO, Chairman of the Commission te VICTOR GILINSKY, Commissioner PETER BRADFORD, Commissioner 17 JOHN AHEARNE, Commissioner THOMAS ROBERTS, Commissioner 18 19 ALSC PRESENT:
20 S. CHILK T. MURLEY 21 H. DENTON S. HANAUER 22 W.
DIRCKS S. TRUBATCH 23 R. KLECKER D. JOHNSON 24 P. RANDALL 5.
VAGANS 25 ALDERSON REPORTING COMPANY,INC,
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CHAIRMAN PALLADINO:
The meeting will please come 3 to order.
4 The subject of today's meeting is a briefing on 5 pressurized thermal shock of reactor pressure vessels.
The 6 briefing is being held in accord with the Commission's 7 continuing interest in this important topic and with its 8 desire to be briefed periodically on progress being made.
9 At this time I succest that we proceed with the 10 briefing and turn the meeting over to Mr. Dircks of EDO.
11 MR. DIRCKS:
Mr. Chairman, this is to give you a 12 status report on where we stand on this issue and to bring 13 you up to date on the recent staff actions that have 14 occurred since the last time we addressed the Commission.
15 Tom Hurley will do the briefing.
Tom, as you 16know, has recently shif tad over to a new position.
But 17 since he had followed this issue up to very recent days we 18 thought he should do it.
Steve Hanauer is there to provide 19 the transition team and will pick up Tom's duties as Tom is 20 phased out.
21 Wi th tha t, Tom, will you begin.
22 HR. MURLEY:
I do this in my spare time at night.
Z3 (Laughter.)
a 24 A lot of work has been done on this topic of 25 pressurized thermal shock since we briefed you first last sa ALDERSON REPORTING COMPANY,INC,
3 1 June.
The stsff conclusions are really the same as we 2 reported them back last June, although we have much more 3 inf orma tion.
Still there is a lot of work that is needed to 4 develop a supportable reoclatory position and that is why we 5 believe that we are still g'oing to need the extra time to 6 develop the basis for a staff position on the matter.
7 So I will discuss this recent information since 81ast September when we were down last and then where we seem 9 to be going.
10 Could I have the first chart, please.
11 (Slide presentation.)
12 I think it is important to recognire that there is 13 no clear-cut time or status of a vessel when a vessel 14 changes from being safe to being unsafe.
I have found tha t 15 a very difficult concept to get across when I discuss it 16 with the media, but it is largel'y a matter of judgment which 17 depends on a good understanding of the risks involved.
18 COHNISSIONER GIIINSKY:
Wait a minute.
I have a 1911ttle trouble absorbing it also.
Clearly there is a 20 continuum and things can get verse and worse and worse and 21 so on, and as that happens the risks go up.
22 HR. MURLEYa That is right.
23 COHHISSIONER GILINSKY:
So in nature there isn't 24 a n y sharp line.
But we have got to decide where ve think we 25 ought to draw the line.
1 l
ALDERSON REPORTING COMPANY,INC,
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MR. MURLEY:
Yes.
2 COMMISSIONER GIIINSKT:
Are you going to address
_ _. - 3 that?
s
- --4 MR. MURLEYs Yes.
That is where we are headed, as
.. __ 5 a matter of fact.
6 COMMISSIONER GILINSKY But I mean that is true of i
Teverything we deal with.
That is true of thickness of
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- 8 containments or just anything.
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9-MR. MURLEYa The goal is to draw that line, that c.
__10 is right.
Hight now our regulations do not place rtny limits 11 on the brittleness of pressure vessels.
The risks 12 involved ---
13 COMMISSIONER GILINSKY Wait a minute.
Isn't one 14 of the appendices to Part 50 devoted to this matter, or an I 15 vrong?
16 MR. MURLEY:
Yes.
Appendix G discusses it, but it 171s mainly cool-down limits and heat-up rates.
It does not 18 place an absolute limit per se on the brittleness in terms 19 of reference temperature that a vessel can reach.
That is 20 w hat we are aiming for, as a matter of fact.
Tha t is the 21 goal of this program.
22 COMMISSIONER AHEARNE:
Are you aiming for some 23 ref erence temperature?
I thought your first comment there 24 was that another way of looking is saying that you can' t 25 sim ply set a single reference temperature and say that will ALDERSON REPORTING COMPANY,INC, I
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5 1 be the criteria.
2 MR. MURLEY:
No, I didn ' t mean tha t.
There is no 3 clear-cut line, that is meant to say, that you could talk 4 about a vessel being safe versus unsafe.
Now, as 1
5 Commissioner Gilinsky points out, nevertheless one has to 6have regulations.
We will do that when we assess the risk.
7 Presumably there will be a safety goal or some kind of 8 target we can analyze.
9 COMMISSIONER GILINSKY Wait a minute.
That is 10 something f or the long term though.
We may not have a 11 regulation now, but we have to have a view on what is 12 acceptable and what isn ' t acceptable.
Are we going to hear 13 about th at?
14
.HR. NURLEY:
Yes.
Our view is that the vessels 15 are acceptable now and that we believe we do need a 16 regulatory limit but it takes time to develop one that is 17 supportable.
We hope to have one, say, by next summer.
18 CHAIRMAN P ALLADINO:
You will address, however, 19 what our risk is in the interim?
20 MR. MURLEY:
Yes.
21 COMMISSIONER AHEARNE:
And what kind or a Z2 criterion or set of criteria you are tentatively looking at?
23 ER. HURLEY:
Yes.
We can talk about that.
24 The items involved clearly are very complicated.
25 This is one of the more, if not the most complicated, type 4
ALDERSON REPCRTlNG COMPANY, INC,
6
-g 1 of regulatory issue that we face because it cuts across many 2 disciplines and many matters.
You have the transients, the 3 vessel properties and so f o rth.
4 COHNISSIONER AHEARNE:
Wouldn't you also add to 5 that list operator action?
6 HR. HURLEY:
Yes, I should have.
That is right.
7 COHNISSIONER AHEARNE:
That seemed to be a major 8 point in auch of the discussion.
9 HR. HUR1EY:
Yes.
10 COHNISSIONER ROBERTS:
Are there many mysteries 11 about the material properties of plate and veld metal?
12 HR. HURLEY:
Yes, there are, because it is 13 irradiated and that does it.
14 The second chart, please.
15 Now, this is a highly schematic curve.
I had 16 hoped to illustrate the following point, that for any given 17 reactor one can presumably construct a curve of the 18 probability of a transient of given severity versus the 19 severity of the transient.
Our experience tells us that it 20 f alls off with severity.
So that there are a whole class of 21 over-cooling transients that one could talk about.
22 We have in the past dwelled very heavily on the 23 Rancho Seco transient because it is one that was 24 experienced.
So we tend to use that as a benchmark in our 25 calculations and it has a certain probability of occurring i
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1 that is shown schematically there.
2 On the other hand, there can be, and we have
('T 3 always recognized that there can be more severe 4 transients ---
5 COMMISSIONER GIL NSKYa You say "which would cause 6 vessel cracking."
Which vessel, the Rancho Seco vessel or 7 some other vessel?
8 MB. MURLEY:
Well, that is my point.
This curve 9 would be different if we could construct it.
This would be 10 different for each reactor.
11 CONNISSIONER GILINSKYa Is this f or the Rancho 12 Seco vessel?
13 NR. HURLEY:
It is just a schematic.
14 COEMISSIONER GILINSKY:
The reason I ask is 15 because last time I believe you or someone else informed us 16 that the Rancho Seco transient in another vessel might have 171ed to cracking.
18 COMMISSIONER AHEARNE:
I think that is consistent 19 with what Tom is saying.
What he is saying is that each 20 vessel has to be analyzed for each series ---
21 COMMISSIONER GILINSKY:
That is what I am asking, i
22 whether that is for the Rancho Seco vessel or not.
l 23 NR. MURLEY:
Well, tha t could be, for example, for
[
24 the Rancho Seco vessel.
Let's say it were.
It has some 25 certain probability of occurring but we would assess that it l
l ALDERSON REPORTING COMPANY,INC,
8 1wouldn't threaten the Rancho Seco vessel now at all and 2 probably not for another, say, ten effective full-power 3 yea rs.
But there could be a more severe transient show down 4 on the curve that could threaten the vessel.
5 COHNISSIONER AHEKRNE:
I think Vic's point though, 6 Tom, is that the last time there was an impression left that 7 the Rancho Seco transient itself could be that transient 8 which would cause vessel cracking in some other vessel, 9 correct?
10 MR. MURLEY Not yet, no.
11 COHNISSIONER GILINSKY:
That is what I thought.
12 MR. MURLEY:
We have analyzed the oldest vessels 13 using our own analysis methods developed largely at Oak 14 Ridge, and we would say that even for the oldest vessel 15 today the Rancho Seco transient would not crack that vessel 16 using nominal properties, that is not the very worst 17 properties that you could imagine.
18 Next chart, please.
19 This is highly technical.
I showed it to the ACRS 20 when we talked to then a couple of months ago.
It is to 21 illustrate the staff 's views that there are a number of 22 margins in the fracture mechanics analyses that are done.
23 Probably the two most important would be the 24 second and third bullets there.
The actual shift in s
25 temperature we think will probably be less than we use in ALDERSON REPORTING COMPANY,INC, G2iMG
9 1 B eg. Guide 1.99.
That will be borne out later as we see in 2 the responses that we got from industry.
3 Similarly, the ASME Code toughness curves that we 4 use in the calculations tend to be, and in fact are lower 5 bound curves.
We don 't know the amount of margins that 6 those two items give us, but we are doing a statistical 7 analysis to try to get a better handle on the margins.
8 Now there are sources of non-conservatisms ---
9 COHNISSICBER AHEARNE:
Could I just ask a question?
10 MB. MUELEY:
Yes.
11 00HNISSIONER AHEABNE:
The first bullet, is it 12 dust that you assume the presence of a flaw, or do you 13 assume a presence of a necessary size flaw?
14 MH. MUELEY:
Of a flaw large enough to initiate a 15 crack.
16 COMMISSIONER AHE?'NE:
Now you don't feel that 17 that also is an important -- (Inaudible).
18 MR. MURLEY:
Yes, it is.
It is a conservatism.
i 19 It is almost impossible to quantify is the problem.
So we 20 take the conservative regulatory posture that we just have 21 to assume a flaw.
22 COMMISSIONER AHEARNE:
But, as I tried to draw I
23 o ut, it is more than just a flaw.
It is a flaw of a certain l
24 minimum size.
25 MR. MURLEY:
Yes, but for the kinds of severe ALDERSON REPORTING COMPANY,INC,
10 1 transients tha t we look a t it doesn ' t take a very deep 2 flaw.
A half an inch, for example, deep flaw can initiate a 3 crack.
4 COHHISSIONER AHEARNE:
Are those commonly found?
5 HR. HUBLEY:
The question is are they commonly 6found?
They have really only started looking with good 7 techniques, as I mentioned last time, ultrasonic techniques 8 recently.
They looked at the Oconee 1 vessel for the 9 ten-year inspection and they found indications.
They are 10 not really cracks, but just small imperfections that can be 11 of an eighth of an inch say deep.
This was the first time 12 tha t ther, using these sophisticated techniques, really 13 looked right underneath the cladding and they found these.
14Now they are not what you would call cracks, but they could 15 initiate cracks for severe transients.
16 COMMISSIONER AHEARNE:
What I conclude from what 17 rou said is that they don't reach the level of the minimua l
18 size that you spoke about.
You said one-half inch I think.
l 19 HR. HUBLEY:
No, a half inch is not necessarily l
20 minimum.
I 21 CHAI3HAN PAL 1ADIN0s You said a half inch, th en 22 you said deep and then you said an eighth of an inch deep.
23 Did you mean the crack -- (Simultaneous Conversations -
24 Ina udible ).
25 HR. MURLEY:
I am sorry.
I didn't mean to imply l
ALDERSON REPORTING COMPANY,INC.
11 1that a half inch was a minimum size for initiating a crack.
1 2 Smaller flaws can initiate cracks if the stress is high j
'T.
3 enough.
4 COMMISSION ER AHEARNEs So there is no minimum size 5 flaw that you would conclude would not lead to the crack 8 initiation which would be of concern ?
7 MR. MURlEYs Let me ask someone from fracture Smechanics.
Ia there a minimum size flaw, Ray?
9 MR. KLECKEBa Not really.
It all depends on the to severity of the transient itself that you assume.
If you 11 assume a very severe transient and if you ignore the eff ect 12 of cladding, then cracks on the order of an eighth inch or 13 quarter of an inch could initiate.
However, with the 14 underclad indication which he is describing here, it is not 15 very likely that that particular flaw would initiate because 16 of the toughness of the clad' over the top of it.
So this 17 gets into some of the assumptions we have to make in the 18 analysis where we feel there are some conse rvatisms.
19 CHAIRMAN PALLADIN0s Is the length of the crack 20 significant or not?
If it is an eighth inch deep and a half 211nch long is that worse or better or not significan tly 22 dif feren t?
23 MR. KLECKEHs The longer the flaw the more likely
/
24 it i<
- o propagate.
A very short flav vould not necessarily 25 initiate.
ALDERSON REPCRTING COMPANY, LNC,
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HR. HURLEY The next chart, please.
2 There are, as I mentioned, some non-conservatisas 3 also.
Ne put this up primarily for completeness.
I think 4 the most important one is really the first one and I have 5 alread y mentioned tha t.
There are overcooling transients 6 that can be more severe than the Bancho Seco transient.
So 7 ve don 't by any means believe that-using the Rancho Seco as 8 a benchmark is the worst that one can see.
9 CHAIRMAN PALLADINO:
But is that a 10 non-conservatism in analysis or dort' t you analyze each 11 scenario as an independent analytical problem?
I can accept 12 tha t first one.
It is certainly true.
13 HR. MURLEY:
Yes.
Actt?. ally it is not a 14 non-conservatism.
We analyze, yes, the more severe 15 transients.
16 CHAIRHAN PALLADINO:
But the other items are truly l
17 non-conservatisms even af ter you have picked the scenario 18 one evaluation ?
19 ER. M'URLET:
I have listed those as potential 20 sources cf non-conservatism, yes.
I mentioned that the 21 RT shift may be higher than the Reg. Guide 1.99.
That NTD Z21s a true statement, but it is very unlikely because the 23 reg. guide was drawn to bound all the data points.
But J
24 there is the chance tha t it could be high.
I 25 COMMISSIONER AHEARNE:
I guess I find difficulty ALDETGON REPORTING COMPANY. INC,
13 1 having one page that possibly the conservatisms are that the 2 actual shif t will probably be less than 1.99 and then on the 3 non-conservatisms that it may be higher than 1.99.
Tha t is 4 too auch fence straddling.
5 (Laughter.)
6 MR. HUBLEY:
We believe unequivocably that the 7 actual shif t will probably be less than Reg. Guide 1.99.
8 COMMISSIONER GILINSKY Remind me what RT is.
NDT 9
HR. MURLEI That is the reference temperature at 10 which the material becomes brittle.
It is defined generally 11 through a Sharpe Test, when a Sharpe specimen would crack at 12 30 foot-pounds.
That is typical.
13 CHAIRHAN PALLADIN0s And that varies with fluence?
14 NR. HURLEY With fluence tha t reference 15 temperature shif ts to higher tempratures, which is to say 16that it becomes more brittle.
17 COMMISSIONER AHEARNE:
Of course, it is not a 18 go /no-go.
It is a definition point on the curve.
19 HR. HURLETs That is right.
20 COHNISSIONER AHEARNE:
So it isn't that on one 21 side it is not brittle and on the other side it is suddenly 22 embrittled.
23 HR. HURLEY:
That is right.
's 24 The ne xt cha rt.
25 Since we met with you in September we have had ALDERSON REPORTING COMPANY,INC,
14 1 seetings with the owners groups.
2 COMMISSIONEH BHADFOBD Tom, I had thought you 3 were going to go down the last chart.
Can you talk a little 4 bit more about the fluence calculations possibly being in 5 error?
6 MR. HURLEY4 Put back on the last chart on 7 non-conservatisas.
8 Now we generally are assuming a plus or minus 30 9 percent or 40 percent uncertainty.
I don 't know exactly for 10 each specific calculation uncertainty in the fluence.
We 11 use nominal neutrsi fluences in the calcula tions.
There 12 clearly is a spread on either side of that.
In some of the 13 Combustion Engineering early calculations they were 14 substantially off in their estimates.
For example, when 15 they pulled the capsule.out of Maine Yankee they found that 16 the fluence was of f by I think about a factor of two in the 17 non-conserva tive direction; that is to say, they were 18 underestimating the fluence.
19 COMMISSIONER GIIINSKY:
Doesn't that mean that you
~20have got an uncertainty in the effective full-power years 21 which is comparable to that?
22 MR. MURLEI:
Yes, if we still had that 23 uncertainty.
Now that began to show up a few years ago in 24 all of the Combustion Engineering calculations mainly 25 because they used a simpler model than other people were ALDERSCN REPORTING CCMPANY. INC, MiLUMYRID /fi4J1Z1&EftYfnfilfdat RA RCM3JKfRf23-fF49
15 1using, a one-dimensional transport calculation.
They have 2 now corrected those for capsule measurements and they do the 3 f ull two-dimensional calculation.
s 4
Furthermore, there is a benchmark research program 5 a t Oak Ridge where they and the other two vendors have taken 6 part and we feel comfortable that they can calculate it to 7 within 30 percent.
8 So the numbers we would quote on any of these 9 fluences and lifetimes would be our best estimates as to corrected today.
11 CHAIHHAN PAlLADINO:
I am not sure I understood 12 the answer to what I thought was Commissioner Gilinsky 's 13 question.
Did you say that this was an error in full-power 14 y ears, effective f ull-power years ---
15 COHHISSIONER GILINSKT An uncertainty.
16 CHAIHHAN PALLADINO:
Tes, an uncertainty, or is it 17 an uncertainty in the correlation between fluence and 18 full-power years, or maybe both, I don't know.
19 HR. HURlETs Well, I understood the question to be 20 the f ollowing.
Suppose we were to quote the vessel life as 2130 effective full-power years and then we made a measurement 22 when we pulled the capsule out and we found our flux was off 23 by a f actor of two in the wrong direction.
Then there would 24 be a direct reduction in our estimate of full-power year 2511f e time.
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1 CHAIRMAN PALLADINO:
It wasn't an uncertainty in 2 what full-power years you had run up to that time, but 3 rather it was a correlation between the fluence --
4 (Inaudible).
~
5 MR. HURLEY:
Yes.
I believe that is right, yes.
6 COHNISSIONER BR ADFORD:
I guess I am still a 711ttle conf used.
I had thought you were using error bands 8 of 20 percent on fluence calculations.
Is that wrong?
9 MR. MURLEY:
That is what we believe we can get 10 down to.
We have more or less demonstrated that on the 11 benchmark program at Oak Ridge.
12 COMMISSIONER BR ADFORD :
What were you using say in 13 the estirstes you gave us when this first came up last
. ~>
14 spring with regard to the seven or eight problem plants?
15 M3. MURLEY:
There we use the mean calculated 16 value.
17 COHEISSIONER BRADFORD4 I see.
So that when you 18 made statements about probabilities of serious events you 19 veren 't using the upper end of the error band but you were 20 using the actual mean calculated value?
21 MR. MURLEY:
For the flux and the fluence; that is 22 rig ht.
Where we use conservative properties consistently is z3 1n the materials properties, and what else, yes, the
~he materials toughness properties.
24 temperature shif t and c
25 For the copper content of the weld and the fluence ALDERSON REPORTING COMPANY, INC,
O 17 1 calculations we use mean values, or so f ar we have used mean 2 values.
3 COMMISSIONER AHEARNE:
What is the uncertainty in 4 the fluence measurement -- (Inaudible).
5 HR. HURLEYs The' uncertainty in the fluence 6 neasurement.
Let me make sure I understand that.
They 7 place foils in the capsules and then they count those foils 8 and from that they back calculate a flux level.
I guess 9 right offhand I don't_ have an estimate for that.
The 10 counting statistics are clearly very precise.
I would have 11 to say it is in the range of 10 to 20 percent would be my 12 estimate, but I can check that.
13 C03MISSIONER BR ADFORD:
I had thought your Oak 14 Ridge report put it at 50 percent.
15 COMMISSIONER AHEARNE:
The measurement?
16 COEHISSIONER BR ADFORD:
Yes.
I don 't have it here 17 though.
18 HR. HURLEY:
Oak Ridge themselves estimated that 19 the calculation that one could use would be plus or minus 50 20 percent.
21 COMMISSIONER AHEARNE:
That is what I thought.
22 HR. HURLEY:
We think we can do better than that 23 and we think we currently are doing better than that once 24 one takes into account the capsule data tha t exists.
25 Chart 5, please.
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18 1
COMMISSION 5R c'LINSKY:
What is our estimate of 2 the effective full-povu. Years that have already been 3 clocked in a reactor' 4
NR. MURLEIa Well, it would be the accuracy of our
^
5 flux calculations basically, and they have been benchmarked 6against the neasurements.
I think the sum of those would 7 probably be plus or minus 30 percent which is where we think awe are today.
9 COMMISSIONEB BHADFORD:
I guess I am still 10 confused about that.
I would have thought that the 11 effective full-power years was a calculation that didn 't 12 have much to do with the flux measurements but had to do 13 with the way the reactor had been run.
14 HR. HURLEY:
Well, it is, but 15 CHAIRMAN PALLADIN0s I wonder if our terminology 161s consistent?
17 COMMISSIONER AHEABNEs I don't think so based on 18 Peter 's question.
19 (Laughter.
20 COMMISSIONER BRADFORDs Well, my terminology is 21 of ten inconsistent, but as long as the rest of you are on 22 the same wave length I will catch up.
But I had been 23 assuming that effective full-power years was a calculation 24 that essentially took the levels at which the reactor had 25 operated and translated them into years of operation at 100 ALDERSON REPORTING COMPANY,INC,
I i
19 1 percent if it had been run that way.
2 HR. MURLEI That is correct.
~'
3 CHAIRMAN PALLADINO:
That is why I found it a necessary to clarif y that earlier.
5 COMMISSIONER BRANFORD:
That is why I didn't 6 understand the answer. to Victor's question which seemed to 7 suggest that somehow the effective full-power years flowed 8 f rom a fluence calculation.
9 CHAIRMAN P&LLADINO:
If I understood his 10 correctly, they are using the terms two ways.
The effective 11 full power lifetime and then we were talking about effective 12 f ull-power years up to a certain point.
He is saying that 131f you had expected the plant to last 40 years as the 14 effective full-power lifetime, then there were some 15 measurements made that would have showed that they were 16 unconservative by a factor of two and said the vessel would 17 have only had 20 years of full-power life.
18 Then we began to talk about effec tive f ull-power l
19 years of operation and that is what I think you were 1
l
. 20 ref erring to here, and I am not sure th e re cen t question was 21 on that subject.
22 COMMISSIONER BRADFORD:
I see.
23 COMMISSIONER GILINSKY:
Well, let's take it back l
24 to the way you first put it, and I am jump'.ng ahead a little 25 bit, but you say in the first item here "at least three l
l ALDERSON REPORTING COMPANY, INC,
l 20 1 effective full power years before concern with any plant."
2 Now what assumptions are made about the uncertainty in 3 deciding tha t?
In other words, what assumptions are made 4 about uncertainty in how fast the vessel J.s becoming
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5 embrittled in effect?
In other words, there is one sigma or 6 two signas or nothing or this is the mean or what?
That 7 applier to any one of them.
I just happened to pick this aone.
9 HR. HURLEYs These are merely reports of what the 10 owners groups told us.
So I can't answer precisely what 11 they mean when they say any number of full-power years.
But 12 in general when we do calculations, the staff does, let's 13 say, or our consultants, we use a straight deterministic 14 calculation.
15 We take a pressure temperature history for a given 16 transient and we then apply tha t pressure temperature 17 history to the vessel to a fracture mechanics calculation.
18 We use a fixed mod 91 and fixed properties generally thought 19 to be conservative and then calculate at what time a crack 20 of a given size might initiate and grow.
21 We then ask ourselves what fluence tha t is at 22 which a crack would grow and instead of talking fluence, 23 which is just flux times time, we tend to talk in effective 24 full-power years.
I mean it is virtually the same thing.
25 COMMISSIONER GIIINSKY:
But I gather it is that ALDERSON REPORTING COMPANY,INC,
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1 connection which is uncertain by the amount that you ---
2 MR. MURLEY:
The answer is we have not yet done a 3 complete statistical analysis of uncertcinties because that 4 involves not only the flux and the copper content by the 5 analysis of toughness properties in the code and ---
6 COMMISSIONER GILINSKY:
But you don't need to do a 7 complete statistical analysis.
What you were telling us, if 8 I understand it correctly, was that there is an error band 9 of plus or minus 30 percent in there.
10 HR. HURLEY:
Yes.
11 COMMISSIONER GILINSKY:
So what assumptions are 12 made in arriving at these various conclusions?
13 COMMISSIONER AHEARNE:
I think there are two sets 14 of uncertain ties though.
One, I thought the conclusion was 15 there is roughly a plus or minus 30 percent on the fluence.
16 MR. MURLEY:
Yes, and that could lead to plus or 17 minus 30 degrees on the reference temperature, for example.
18 COMMISSIONER AHEARNE:
Then there are other 19 uncertainties in the materials properties area.
20 HR. MURLEY:
Yes.
21 COMMISSIONER AHEARNE:
And you have to fold both ZZ of those together to reach a conclusion on what is the 23 uncertainty in the effect of full-power years remaining.
24 COMMISSIONER GILINSKY:
Well, folding all those 25 things in, are these and other results that you will ALDERSON REPORTING COMPANY, INC, M /XfL E10 M/$MXRii@TA f@R FR@b (976Fa 61p0-89$
I 22
.m 1 present, are they saying that that is when you get to the 2 edge of the uncertainty band or is that when you are getting
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3 to the mean of all the assumed properties?
~i 4
CHAIRHAN PAL 1ADIN0s Do they really mean at S least?
By at least I would presume to be that the tolerance 6 is minus zero plus perhaps two more years if I were bounding 7 the uncertainty.
Or is it three years plus or minus --
8 (Inaudible).
9 NR. HURLEY:
Keep in mind this is an assertion on 1]their part.
They have not presented us with the report.
We 11 will get that at the end of December.
12 CHAIRMAN PALLADIN0s But even when they give this, 131f they say at least we ought to have knowledge as to
.s
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14 whether or not they have made this the lower bound in their 15 uncertainties.
i 16 MR. HURLEY:
Yes.
17 HR. DENTONs But these uncertainties are sort of l
18 sutsumed within the first part Tom 's presen ta tion.
That is l
19 a probability of a given transient.
I mean it might be i
20 minus ten years for a transient ve ry severe that you l
l 21 couldpostulate at a very low level of prcbability.
There Ztare probably a lot of physical uncertainties on the 23 metallurgical side and the heat transfer side and the i
L. -
24 operator's side.
I think the fluence one is not nearly as 251arge as the uncertainty over probability of any given l
ALDERSoN REPORTING COMPANY,INC, I
N
9 23 1 transient.
2 CHAIRHAN PALLADINO:
Well, of course, I am not 3 reading the actual Westinghouse document.
But when I read 4 that at least three effective full-power years are remaining 5before concern with any plant, I would mean by golly 6
COMMISSIONER AHEARNE:
That is assuming a set of 7 transien ts.
8 HR. DENION:
That is assuming a certain transient.
9 CONHISSIONER AHEARNE:
Yes.
10 CHAIRMA1 PALLADINO:
Where did it sa y that?
11 COMMISSIONER AHEARNE:
In the report they sent 12 down.
I 13 CHAIRMAN PALLADINO:
Oh, okay.
14 HR. HURLEY :
The Westinghouse plants vary.
There 15 a re t wo loo p, three loop and four loop.
Generally the most te severe transient is a large steamline break.
We assume the 17 probability of that is actually about ten to the minus four 18 per reactor year, which is quite low.
We don't have any 19 statistics, but those are the estimates taken from WASH 1400.
20 So given such a low probability transient, they 21 would say that they have at least three eff ective f ull-power 22 years before the vessel would crack even for that transient.
23 CHAIRMAN PAlLADINO:
Which is the worst.
24 HR. HURLEY :
Which.is the worst, yes.
25 COMMISSIONER BRADFORD:
Well, let's see now, does ALDERSON REPORTING COMPANY, INC,
24 i
1 the word " concern" then, is that synonymous with the vessel 2 would crack?
3 MR. MURLEY:
Yes.
4 CONHISSIONER GILINSKYa I guess we would be 5 concerned at that point.
6 MB. MURLEY Yes, but keep in mind we are still 7 talking about a very low likelihood event to crack the 8 vessel.
9 COHHISSIONER BRADFORD:
If you assume the Bancho 10 Sece type event instead of the event that was assumed there, 11 how does that change the number of effective full-power i
12 years ?
13 NB. MURLEY:
I don't have that calculation.
I 14 j ust don 't have it, but it would clearly be more than three 15 because the Hancho Seco transient is just not as severe as a 16 steamline break for a Westinghouse plant.
17 CHAIRMAN PALLADIN04 So you are saying for a 18 Westinghouse plant, considering the worst though improbable 19 sccident, that there would be at least three effective 20 full-power years before any one of them would be in danger 21 of f ailing?
22 MR. DENTON:
That is what Westin ghouse says.
23 HR. MUBLEY:
That is their assertion, yes.
24 CHAIBHAN PALLADIN0s Their assertion.
25 MR. DENTONs This chart is just intended to give ALDERSON REPORTING COMPANY. INC, k
25 1 you the benefit of their views -- (Simultaneous 2 Conversations - Inaudible).
3 CHAIRHAN PALLADIN0s We are trying to understand.
4 COMMISSIONER GILINSKYs How old are some of these 5 plants?
6 HR. DENTON:
We have gotten data broken down ---
7 COHNISSIOWER GILINSKY:
Roughly.
8 ER. DENTON:
Ten years.
Take Yankee, that is a 9 very old plant, although it is not one that is on my list. I 10 think around ten years for the plants that we are looking at.
11 ER. EURLEY:
Yes, the H. B. Robinson / San Onofre 1 12 class, which I guess is late Sixties or early Seventies.'
13 CHAIRMAN PALLADINO:
Why don't you go ahead and 14 make your presentation.
I do think though it is important 15 that we understand wha t it is these people are asserting.
16 HR. HURLEY:
Yes, it is.
Before I go on I want to 17 reiterate that this is really just reporting what they told 18 us here.
19 COMEISSIONER GILINSKT:
I don't understand.
I 20 wonder whether you have instructed them to report in such a 21 way that we understand how the uncertain ties in the various 22 phases of this calculation enter into the result?
23 MR. EURLEY:
Well, not having the report, but we 24 have asked for an understanding of how they did the 25 calculation and what the uncertainties are.
ALDERSON REPORTING COMPANY. INC,
O 26
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1 NR. DENTON:
This is due at about the end of 2 December.
3 HR. MURLEY:
The end of December, that is right.
4 There is no consistency amongst these three calculations and
~
5 three numbers.
So you can't really compare Westinghouse's 6 assertion of three where they use actually a very serious 7 transien t.
8 COMMISSIONER BRADFORD:
Tom, let me stop you 9 again.
They have already done the calculation and furnished 10 you with the results.
Why do they need until the end of 11 December to provide you with the calcula tio n ?
12 MR. MURLEY:
They have not furnished us with the 13 results.
They have furnished us with a statement like this.
14 COMMISSIONER AHEARNE:
They gave letter reports on 15 0ctober 20th ?
16 HR. MURLEY:
Yes, we have had letter reports and I 17 guess you can call them interim meetings.
18 HR. DENTONs The original date was the end of the l
19 year to finish the study and then we would meet with then l
20 periodically and get reports back on how it is coming out.
21 So va just wanted to give you where th ey say it is coming 22 o u t, but it is going to take them until as long as we gave 23 them to finish the study and give us the report.
l 24 COMMISSIONER BRADFORD:
But it is the kind of i
25 study in which it is possible to know the answer and still ALDERSON REPORTING COMPANY,INC, t
27 1 be a month and a half away from being able to furnish the
^
2 study?
3 HR. DENTON4 Yes, and no.
4 COMMISSIONER BRADFORD:
Okay.
5 HR. DENTON:
Ther'e is still some amout of work 6 going on in this area in looking down details and there are 7 myriads of calculations, and, as you might expect, the staff 8 and the utility differ on most every assumption that goes 9 into some of these things. If you ask them today where they 10 think they are coming out, then this is what they tell you.
11 CONHISSIONER AHEARNE4 As I recall, what we asked 12 them to do was. to give a quick response and to give their 13 best quick estimate of how serious vas the problem in their 14 plants and that is what you are reperting on and we have 15 these October 20th, I recall, letter reports.
16 COHNISSIONER GILINSKY:
But if we don't understand 17 wha t the response means ---
18 COMMISSIONER AREARNE:
Then we also asked them to 19 do it in more detail.
20 CHAIRMAN PALlADINO:
But I do gather you 21 understand what the response is intended to mean in terms of 22 words anyhow.
23 HR. MURlEY:
In terms of words we don't know the 24 details of the calculation.
That is why the staff can't v
25 endorse these toda y.
It wouldn ' t surprise me that when they ALDERSON REPORTING COMPANY, INC, 400 VIRGINIA AVE, S.W., WASHINGTON, D.C. 20024 (202) 554-2345
28 1 come in if it is two effective or four effective full-power 2 years.
I mean, they are fine-tuning their calculations.
3 This is what they told us in September.
4 COMMISSIONER BRADFORD:
The bottom line of each of 5 the three seem to suggest that there is almost a different ureporting basis involved.
7 NR. HURLEYs There"is.
8 CORNISSIONER BRADFORD:
The Westinghouse three 9 does not take credit for operator actions is that righ t ?
10 MR. DENTON:
That is one of the keys.
If you 11 allow cr edit for proper operator action tr.e operator can 12 kee p you out of trouble.
13 COMMISSIONER BRADFORDs In almost any case.
14 HR. DENTON:
And in a. lot of things other than 15 just thermal shock yoa have to rely on the operator to keep 16 you out of trouble.
We have been criticized I guess by the 17 ACRS for getting into this with an assumption that you 18 couldn 't take credit for operator action because that 19 assumption almost always leads you to trouble if you keep 20 calculating long up and no operator actions.
21 BEW, for example, does take credit for operator 22 action.
So part of our view has been to see how realistic 23 is it to take credit for that.
If you allow credit for 24 proper operator actions in most scenarios, it really extends 25 the plant life because he can say well you keep the pressure ALDERSON REPORTING COMPANY,INC.
--n-__na---.
29 1 within reasonable bounds.
2 CONHISSIONER BRADFORDs I think B&W of all people 3 would be sensitive to the perils of that assumption.
4 CONHISSIONER AHEARNE:
Yes, but at least as I read 5 their submissions at least at the moment they didn't seem to 6have much other choice.
7 CHAIRHAN PALLADIN0s What do you mean they didn't 8 have much other choice?
9 COHNISSIONER AHEARNEs Well, at least reading th e 10 materials they have submitted it seemded that the var ther 11 were able to conclude that there was service life, the 12 eff ective f ull-power years remaining, was by allowing f or 13 opera tor action.
Maybe I am reading something that is not 14 there, but my reading of the material was that at the moment 151f they don 't allow operator action then they couldn 't reach 16 a conclusion that there is not ---(Simultaneous 17 Conversations - Ina udible ).
18 MR. HURLEY:
I think that is fair.
For example, 191f one just uses the Rancho Seco transient, which was a BCW 20 plant, I think we are virtually certain that the plants 21 cannot go their full service life, that is 32 effsetive 22 full-power years, and still withstand a Rancho Seco 23 transien t.
24 COHHISSIONER AHEARNE:
But it is even more than 25 tha t, isn't it?
ALDERSON REPORTING COMPANY,INC,
4 30 1
MR. HURLEY:
Yes.
We can probably come close to 2 that.
Then you get into anomaly of how can you take credit
^
3 for operator action when you have got on the books already a 4 transient where the operator didn't take the right action.
5 He didn 't have enough inf or'mation to take the right action.
6 COHNISSIONER BRADFORD:
Tom, are their situations 7 with regard to BEW plants in which if the operator doesn 't 8 take useful action you would have a problem if the Rancho 9 Seco transient occurred today?
10 ER. MURLEY:
No.
If I understood your question, 11 is there any plant today that would be threatened, the 12 vessel would be threated by a Rancho Seco transient?
13 COHNISSIONER BRADFORD:
Yes.
14 HR. HURLET:
The answer is no.
15 MR. DENTON:
Remember, that is how we looked at 16 this the first time.
17 COHNISSIONER BRADFORD4 Hight.
18 HR. DENTON:
Let's just repeat that and in every 19 plant where they are, are we seriously concerned about them, 20 and that is what led us to think we have got a little bit of 21 time to look ---
22 COHEISSIONER BRADFORD:
I was trying to get behind 23 the exchange that Tom was having with John rega rding the 24 extent to which BCW had to rely on operator action.
I was 25 wondering if it was turning out that the B&W calculations ALCERSON REPORTING COMPANY, INC.
31 1 were suggesting that they had a problem as of today without 2 operator action.
<w 3
COMMISSIONE3 AHEASNE:
But you prefaced it by a 4 Rancho Seco transient.
5 CONMISSIONER BBAD' FORD:
Yes.
What should I have 6said?
7 COMMISSIONEH AHEARNE:
Is that the most esvere (Inaudible.)
a transient that 9
5H. DENION :
I get the feeling that we all want a 10 bottom line.
11 C0!MISSIONER AHEARNE:
Eventually.
12 MH. DENTON:
We don't know a lot more today than 13 when we briefed you last, except we will give you the
~
14 results of the information we have obtained from those eight 15 licensees that we sought information from and report on a 16few = ore meetings and discussions.
Basically this 17 inf ormation on this chart is the same as we had at the last 18 briefing with you.
We have had no substantive input since 19 tha t tim e.
20 COMMISSIONER GIII,NSKY:
Let me understand.
21 Suppose we were talking about the transients comparable to 22 those that were used in the Westinghouse analysis which from 23 w ha t you sar I gatner were more severe than say the Hancho 24 Seco tra nsient.
25 MR. MUR1EY:
Yes.
Ihe steamline break, the large ALCERSCN AEPCATING CCMPANY. INC.
32 1 steamline break for Westinghouse and Combustion plants is 2 the most severe overcooling event.
3 CONNISSIONER GILINSKY What is it for the BCW7 4
HR. MURLEY:
For BEW it is not so clear.
It is 5 probably a feedwater transient, a so-called run-a way 6 f eedwater transient. because their steam generator is 7 differento It doesn't have as auch thermal heat capacity.
8 COMMISSIONER GILINSKYs Where are they today if 9 they don 't take credit for operator action with one of those 10 transients?
11 MR. HURLEY:
Well, the Oak Ridge report showed 12 that if one had a very, very serious feedwater transient it 131s possible to crack the vessel today, you know, assuming 14 the conservative f t:cture mechanics calculation that was 15 done.
16 COMMISSIONER AHEARNE:
Since you have brought up 17 that particular one, I thought that both the Oak Ridge 18 report and then Duke response pointed out that there were a 19 num ber of f ailures that had to occur to get there.
20 MR. MURLEY That in right.
That is an extremely 21 unlikely event.
It is like ten to the minus fifth per 22 reactor year or less according to our analysis.
The staff, 23 as you know, looked into that.
24 COMMISSIONER AHEARNE:
Tha t gets back to Harold's 25 point that you really have to look at the particular l
l ALDERSON REPORTING. COMPANY, INC,
33 1 scenario and which particular set of transients the 2 probability is associated withs 3
3R. DENTON:
Thare really is no cliff in this area 4 that if you are here you are perfectly safe and if you are 5 here you are perfectly unsafe.
It is a probability space.
6 You look at the frequency of the transient and how severe 7 they are, as Tom said, what the vessel properties are and 8 rou postulate a lot of things going wrong.
You would 9 postulate a very severe shock and the vessel properties have 10 to be exceedingly good to withstand that.
11 COREISSIONER GILINSKY:
Are the owners waiting for 12 the results of these calculations before they think about 13 what they might do?
14 MB. DENTON:
That is why we wrote to the selected 15 group to get those people thinking individually about what 16 remedies might be available to them.
We are waiting I think 17 f or the results for the vendors to come up with what sort of 18 crit (ria might be appropriate to apply.
19 COMMISSIONER GILINSKY:
Do the owners have a good 20 understanding of this problem or are they relying antirely 21 on the vendors?
22 MR. DENTON:
They are relying heavily on the 23 vendors.
Now, I think they have come a long way since we 24 started this ---
25 COMMISSIONER AHEARNE:
Also, it depends on which ALCERSON REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON. D.C. 20024 (202) 554 2345
34
.s 1 owners.
These I gather, at least reading the material that 2 Duke was submitting, it seems that they are pretty well 3 along in their understanding.
4 NR. HURLEY:
I might add that EPHI has recently
~
5 cranked up their program across the board in this area.
So 6 there is a pool of expertise there for the utilities to draw 7on.
8 CONHISSIONER AHEARNE:
Tom, on the last item, do 9 you have any comments on the reliance on vars prestressing?
10 MR. MURLEY:
Yes.
Of course warm prestressing is 11 a phenomenon that can help provent crack initiation during 12 certain transients.
We believe it has been demonstrated for 13 the large LOCA, that is where you don't get repressurization 14 and just overcooling, tha t warm prestressing vill prevent a 15 crack f rom going all the way through the wall.
I should say 16 one has to have confidence that he knows the course, the 17 time pressure history of the transient before you can take l
18 credit for warm prestressing.
19 The types of transients that we are dealing with l
20 here whether there is operator intervention where he can 21 raise the pressure and lower the pressure by turning on high 22 pressure injection, for example, we are very reluctant to l
23 take credit for warm prestressing.
24 So that is going to be a source of contention 25 between us and the industry because if warm prestressing is ALDERSON REPORTING COMPANY,INC.
m
35 1 eff ective it will prevent crack initiation or propagation, 2 but we can't be sure it is going to be operative in all 3 these transients.
So that is where we come down on it.
4 Slide six, please.
5 We met with Germany in late September and there 8 are three points that I should make there.
7 For a couple of their older plants they have 8 decided they have a problem and they have removed outer fuel 9 elements.
10 COHNISSIONER GILINSKYt Let me ask you, do those 11 plants have more of a problem than our older plants or less 12 of a problem?
13 HR. HUBLEYs.
About the same.
14 COHNISSIONER GILINSKTs About.the same.
15 HR. HURLEY:
If they had not taken action.
For 18 example, I think on Obrigheim their fluence would have been 17 nine times ten to the 19th I believe if they had not taken 18 action.
Having taken action, they are going to hold it to 19somewheLe in the low few times ten to the 19th fluence range.
20 COHNISSIONER GILINSKY:
How large are those 21 reactors ?
22 HR. HUBLEY:
About 600 megawatts.
l 23 CONHISSIONER GILINSKYs Wha t made them feel that l
l 24 ther ought to be doing this now?
- m..
25 HR. HURLEY:
Just this problem of maintaining ALDERSON REPORTING COMPANY,INC, mummm mm em mum
36 1 toughness of the vessel.
2 COHNISSIONER GILINSKY:
Why aren' t our owners
^
3 convinced that they need to do something now?
The 4 consequenc7s of something happening to one of these vessels, 5 even apart from harm to the public, is very, very serious.
6 HR. HURLEY:
Oh, yes.
A plant would not operate 7 again if it crackr.d clearly, even if the crack didn't go a through the wall.
I don't know how you.would repair ---
9 COHNISSIONER GILINSKY:
I as just surprised tha t 10 there is not more interest in moving f orward with this sor
- 11 of at least a partial solution which seems to me not a very 12 expensive way of coping with the problem.
At least it slows
.~
13 down the effect of f urther irradia tion.
~
14 HR. HURLEYs I should point out that Westinghouse 15 has a scheme, and we just learned about it a few months ago, 16 called' their low leakage fuel cycle option I think it is j
17 called.
It reduces the flux to the vessel by I believe 20 1
18 to 30 percent at virtually no increase in fuel cycle costs.
19 I as told many of the reload cores coming in now tha t the 20 utilities have chosen that option.
So they are taking some 21 steps in this regard.
22 CHAIRHAN P ALLADIN0s Did the Germans predict a Z3 more adverse condition for their plants than we predict for 24 ours?
25 HB. HURLEY:
As I said for Obrigheim, I think e
ALDERSON REPORTING COMPANY,INC,
37 1 their end-of-life fluence would have been nine times ten to 2 the 19th which is very high and probably higher than ours I 3 would quess.
They determined this from surveillance test 4 cap sules.
So they decided to take acticn.
I believe this Swas about three years ago that they took action.
6 For newer plants they have placed a regulatory 711mit of one times ten to the 19th fluence on the'ir vessels 8 and they mentioned to us an overcooling transient early in 9 the life of their Neckarves theim plant which I only mention 10 here as another example of overcooling transients.
11 A safety valve stuck open.
The plant was not 12 critical and not operating.
You may think that that is 13 good, bu t it is really not.
It makes an overcooling 14 transient worse because,there is no decay heat to keep the 15 fluid temperature higher.
16 They also have much larger safety valves on their 17 steam generators then we do.
So they got a very large 18 blow-down of the secondary coolant and the cold leg 19 temperature in one loop now of the affected steam generator, 20 d ropped to 320 degrees in about five to ten minutes.
We 21 don 't ha ve yet the complete details on the transient.
t 22 I might add this was a fresh vessel.
So it was l
23 no t really threatened.
But it adds some statistics to our j
24 class of overcooling transients.
25 Just as important here, the pressure decreased ALDERSON REPORTING COMPANY,INC,
38 1 down to 1400 pai and the pressure then increased back up.
I 2 have not been able to find out, but I an almost certain that 3 it was the safety systems that came on and the operators 4 repressurized it.
)
5 The next chart starts to show the results that we 6 have gotten from the 60-day responses from the eight 711censees. -The key aspect of this chart is the comparison 8 of the reference temperatures in the right two columns.
The 9 NBC staff using our regulatory guides and the best knowledge 10 we had of the veld properties had estimated the reference 11 temperatures in the next to the last column.
12 The licensees have given us their estimates now 13 based on generally a more thorough understanding of their 14 own vessels.
As you can see, the temperatures are generally 15 lower.
16 There are two main reasons for this.
One is that 17 the initial reference temperature, that is the reference 18 temperature of the virgin material, is lower for the CE 19 vessels.
New this is yet still an assertion on their part, 20 b ut they.have gone back to some archive samples that they l
21 k eep and I suspect that they will be able to sustain that.
22 Tha t is, I believe they will be able to convince us with 23 some more thorough looking.
1
[
24 Also, they have more information on their weld m-25 materials.
There is a class of vessels tha t have low nickel l
l ALDERSON REPORTING COMPANY, INC, t
39 1 allor velds.
We are finding that they have a much lower 2 shif t.
That is, for some reason, which we don't understand, 3 the low nickel velds do not embrittle as fast a's high nickel 4 velds and there is a class of those. reactors.
5 Let's go to the next chart.
6 CONHISSIONER AHEARNE:
One question on that other 7 chart, if I could, Tom.
8 MR. MURLEY:
Sure.
9 COMMISSIONER AREARNE:
Did all of the licensees to come in with plant specific analyses?
11 NR. MURLEY:
I wouldn ' t call them analyses.
We 12 didn't ask for analyses.
We asked for what is the status of 13 your vessel.
14 COMMISSIONER AHEARNE:
Are the staff estimates 15 similarly an estimate for each plant or is it more generic?
16 MR. MURLEY:
Our estimates were for each plant.
17 We didn ' t just take every CE plant and lump it.
18 COMMISSIONER AHEARNE:
So the comparison is 19 between the two column s -- (Inaudible).
20 HR. MUELEY:
Yes.
Now some licensees are going to 21 have to go back and do some further checking.
Like Fort ZZ Calhoun has got to go back and get some more information on 23 their archive samples, f or example, but generally it was 24 plant specific.
25 The conclusions we have so far drawn f rom this, 1
ALDERSON REPORTING COMPANY, INC, MYTC+TtFG@mJ6ueJW#nB&Rt_99M&r%__ __ _______.__-__-_-
40 1and I call them preliminary, is that the reference 2 temperatures may be lower than the staff estimates.
I think 3 that is shown by the chart.
4 Our earlier estimates for the low nickel velds are 5 probably what I call substa'ntially conservative and it would 6 well be 100 degrees or so.
7 Those plants we think are going to be San Onofre 1 8 and probably Calvert Cliffs 1, H.
B.
Robinson and 9 Connecticut Yankee.
10 CHAIHHAN PALLADIN0s What about them?
11 MB. MUBLEY:
They we believe will be able to 12 substantiate that they have low nickel weld material.
- See, 13 ther have got to go back to Combustion Engineering i '
14 Chattanooga plant and dig out the records and the archives 15 samples.
16 If that holds up 17 COMMISSIONER AHEABNE:
You said Connecticut Yankee.
18 MB. HURLEY:
Connecticut Yankee, yes.
They are 19 not on this list.
But nevertheless, we have predicted a 20 very high reference temperature for Connecticut Yankee.
21 Finally, that f urther staff analysis is needed on ZZ this.
23 CHAIBMAN PALLADINO Looking at these numbers, I 24 quess I could conclude that the lower the better.
25 MR. MURLEY:
Yes.
ALDERSON REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554-2345
41 1
CHAIRMAN PALLADINO:
But I don't have any base or 2 a threshold is what you are telling me?
3 MR. MURLEY :
That is what we are going to be 4 struggling with for a regulatory limit.
Let me go on to 5 chart nine.
6 We asked these eight licensees, what would you 7 propose for a regulatory limit on reference te m pe ra ture.
8 They came back uniformly and said they don't think that a 9 single reference temperature is an appropriate limit for 10 continued operation.
The reason for that is that it is a 11 very complicated issue and it depends on the transient that 12 rou are trying to protect against and so forth.
On the 13 other hand, they did not provide any alternates for a 14 regulatory limit for continted operation.
15 I think the staff has an open mind if there is 16 another proposal that one could use.
Not having heard any 17 better ones, and in fact I tried to scope out what might be 18 a diff erent types of limit and I got into a very complicated 19 evaluation model that would be required.
I think in th e 20 lonc run 1E would f ar simpler to have a simple limit.
21 CHAIRMAN PALLADINO:
Tom, I don't understand their 22 argument quite.
Even though they have a whole bunch of Z3 assumptions and a whole bunch of scenarios, could you not 24 define a reference temperature that you ought to be below, 25 below that temperature, so that you don't run the risk of ALDERSON REPCRTING COMPANY,INC.
&AMliFYMD o
-%2 I
^
1 f ailure or scenarios or wha tever they decide as the one that 2 designed it?
3 ME. NUBLEY:
That was the staff's proposal that 4 there be such a limit.
5 CHAIRMAN PALLADIN'0:
I don't understand their 6 argument why they can't do that.
7 ER. EURLEY:
They don't think it is appropriate.
8 I am not sure I can ascribe motives.
I can guess, and thnt 9 is that they think to be conservative we would have to set 10 it so low today that it would give them serious probleas.
11 CHAIRHAN PALLADINO:
That I can understand.
12 HR. MUELET:
I am pretty sure that is their 13 p ro blem.
(
14 CHAIBHAN PALLADINO:
(Inaudible.)
15 3R. EURLET:
I might reiterate that our reguitions 16 don ' t put a limit at all on vessel embrittlement today.
17 There is a Reg. Guide 1.99 that sets a limit of 200 degrees 18 Fahrenheit at the quarter thickness.
That of course is not 19 a regulation and f urthermore it only applies to CP's 20 docketed af ter 1977, which is a null set.
21 (Laughter.)
22 COMMISSIONE3 AHEARNE:
Of course one of th e 23 dif ficulties you are obviously struggling with is trying to 24 e stablish a regulatory criterion in an area with at the y
25 moment auch uncertainty.
ALDERSON REPCRTING COMP ANY, AC, 400 VIRGINIA AVE S.W, WASHINGTON D.C. 20024 (202) 554-2345
4 43 m
1 MR. HURLEYa Yes.
Now we asked them also about 2 operating procedures.
'N 3
No. 10, please.
4 They did respond.
They of course all have high 5 pressure injection termination criteria and instructions for 6 terminating the feedwa ter flow.
Generally we found that the 7 operating procedures place more emphasis, much more emphasis 8 on maintaining ECC flow than on preventing pressure vessel 9 overcooling and this is a natural result of the Three Mile to Island lessons.
11 CHAIRHAN PALIADIN04 But if it was ECC flow and 12 that. vas the only problem, then you could heat up the ECC 13 and solve that problem, could you not?
14 MR. HUBLEY:
Yes.
15 CHAIRMAN PALLADIN0s But tha t isn 't the only 16 problem.
If for those where that is a worry, that could be 17 solved.
18 HR. HUR1EY:
The ECC flow though becomes a problem 19 because even for overcooling transients tha t are initiated 20 in the secondary system like feedwater flow, the pressure 21 comes do wn to a point where the HPI comes on generally.
We 22 have seen it in a lot of transients now.
The operator has Z3not yet diagnosed what is going on.
He knows the high 24 pressure injection system is on so he tends to keep it on 25 even though he doesn 't have to and I guess that is the point ALDERSON REPORTING COMPANY. INC,
44 1 here.
2 CHAIRM AN P ALLADINO:
You mean you run out of hot
(
3 water?
4 MR. MURLEY:
No, that is overcooling the vessel.
5 He thinks his most importan't job is to keep the core cool, 6which of course it is, but once the coolant is already 100 7 degrees subcooled in practice he could turn off the HPI 8 pumps, but they are no t instructed to do that.
It is left 9 up to their judgment.
10 The conclusion is from this that the staff will 11 take steps t<> have the industry improve their operating 12 procedures and training to mitigate these overcooling 13 transien ts.
14 The next chart. please.
15 Oak Ridge, as you know, did a sta te-of-the-a rt 16 analysis.
We have sent the report down to you and we have 17 done our own analysis of the report.
Generally the 18 conclusions are that for Oconee 1,
which was the plant tha t 19 ther used, they found tha t the Rancho Seco event would not 20 pose a threat to the vessel for about 15 more eff ective 21 full power years, but that for some very severe transients Ztusing conservative analyses it could pose a threat to the l
23 vessel today.
24 The next chart.
25 CHAIRMAN PALLADINO:
That brings me to where I was ALDERSON REPORTING COMPANY, INC, l
. _ _ 00 VIRGINIA AVE., S.W WASHINGTON, D.C. 20024 (202) 554-2345 4
45 1 a while back.
When I read that I got concerned.
I said 2 rather than comfort I got discomfort f rom the ORNL report.
3 Then I asked for a briefing and at the end of the hour I had 4 a little bit of comf ort, but now you have brought me back to 5 discomfort again.
6 (Laughter.)
7 CONHISSIONER AHEARNE:
Well, if you turn the chart 8rou will get the briefing.
9 (laughter.)
10 MR. MURLEY:
It gets back also to that schematic 11 cha rt.
There is a transient that one can postulate, it is 12 not impossible, that will crack the vessel, yes, but it is 13 very, very unlikely, we think much more unlikely than other
~
14 threats to the core melt that we already live with today 1511ke ATWS and some things like that that need to be fixed.
16 COMMISSIONER GILINSKY Let's see.
You think ATWS 171s more like than this?
18 ER. NURLEY:
Than this run-away feedwater 19 transient, yes.
20 COMMISSIONER AHEARNE:
That is this particular 21 transient -- (Inaudible.)
22 CHAIBHAN PALLADINO:
This particula r --
23 (Inaudible. )
24 MR. MURLEY:
The NRC staff reviewed it.
We said 25 that some of the calculations were very conservative.
For ALDERSON REPORTING COMPANY,INC, M MIHFfRM CNL @E WCfMR@TtERL 9.C. fM80 WF@ @@G-MS3
46 1 the Oconee calculation of the run-away feedwater transient, 2 some aspects were actually unrealistic.
They used more 3 water to cool down the steam generator than is really 4 available.
5 CHAIRMAN PALLADIN'0 Tom, I also got the 6 impression there were inconsistent sets of assumptions 7 between the various parts of this analysis that were brought 8 together.
9 HR..HURLEYa Yes, there were some.
10 CHAIRHAN PALLADINO:
Is that going to be corrected 11 1n some -- (Inaudible).
12 HR. HURLEY:
I don't want to dump on Oak Ridge too 13 b ad ly.
They picked off the shelf the calculation that was 14 done over a year ago, and it was done back when we were just 151n the early stages of looking at this problem as a bounding 16 calculation.
We said let's do a quick and dirty bounding 17 calcula tion.
That was done and no one ever went back and 18 cleaned it up.
Oak Ridge used it because we had put them 19 under pressure, the research staff asked them to do it in a 20 hurry.
So now they have got to go back and make more 21 realistic calculations.
22 I think the bottom line there is that the 23 probability of these severe transients we think is 24 suf ficiently low that corrective action is necessary.
So we 25 didn't really change our minds at all based on the Oak ALDERSON REPORTING COMPANY,INC.
NO MQORIO IML ftQm QCf%IN@T@N, @.@. 85:384 (8B8) 900-8&2@
47 1 Hidge ---
2 COEMISSIONER GILINSKYa Let me pursue this a 3 little bit.
let us even suppose that right now we are not 4 at a point where we fear that vessels will crack very soon.
5 Still doesn ' t it make sense to maintain that margin and do 6 the kinds of things that the Germans are doing?
We should 71n ef fect do precisely that.
They just keep that margin in 8 front of you.
9 MB. DENTON:
Tha t is why we asked these eight to 10 propose remedial measures.
We thought we didn't have to ask 11 them in 30 days.
So we gave them a little time to do it 12 because the temperature shift is only 10 degrees a year.
13 But each one of these that we have tagged as being a high
~
14 shifter, we have asked for the impacts and the benefits of 15 removing fuel and heating up the ECCS vater and other 16 remedial measures and I think we will have a proposal soon.
17 But we have got to give them a chance to explore the 18 ramifications of each fix before we propose one.
19 COMMISSIONER GIIINSKY:
Well, I am glad to hear 20 tha t.
I somehow was getting the impression that the owners i
l 21 were not much seized with the problem. I hope I am wrong.
l 22 MB. DENTON4 No, you may be right about that.
23 COHEISSIONER GILINSKYs That is really what I was 24 addressing, and I am surprised that they are not more eager 25 to hang on to whatever margin they have got, you know, even ALDERSON REPORTING COMPANY,INC, cf@ VIER 6PTV3 /.M1Jk@ WMHIMT@NmD.@. TM4 GOM R54-M45
48 1 if they are three years away or five years away or whatever i
I 2 it is from real trouble.
m 3
CHAIRHAN PALLADIN0s Even 15.
4 COMMISSIONER GILINSKY Or even 15 as the Chairman 5 says.
I find it very hard "to understand because if I owned 6one of those vessels that is what I would be doing.
7 COHNISSIONER AHEARNE4 In the German dummy 8 element, does it reduce the flux or does it shift the flux?
9 HR. MURLEYs I reduces the flux and also shifts it 10 a bit.
It reduces the peak which is what counts.
11 CHAIRMAN PALLADIN0s How much did they reduce it?
12 ER. HURLETs Ch, I don't recall, but it is like a 13 f actor of two or more I thinki t
~
14 You recall that the last time I told you about 15 this Finnish reactor, Loevisa (?).
They had done the same 18 thing just two years ago.
There they removed the whole 17 outer row of fuel and they got the flux down by a factor of 18 three by doing that.
19 COMMISSIONER AHEARNE:
As I recall in one of the 20 reports that you sent down there is a set of calculations, 21 and it could be for a Westinghouse, for a substitution fuel 22 array, and there it says with increased f uel costs by two 23 and a half percent in that particular proposal.
Is that the 24 kind of margin that leads them to conclude tha t they want to 25 d o --
(Inaudible.)
ALDERSON REPORTING COMPANY,INC, 13 N E 0%L 29nG3M80,0.@. 2Esec Gia geo-8D'@
0
49 1
ER. HURLEY:
Well, clearly, that is the dra-vback 2 that I guess the utility would see.
3 COMMISSIONER GILINSKI:
As John points out, we are 4 not talking about anything very drastic in terms of derating 5 the plan ts.
We are talking about a couple of percent to 6quard against contingles that are going to have a lot more 7 effect. than a couple of percent.
8 HR. HANAUERs Well, there is another aspect of 91t.
If you take the outer row of fuel out you increase the 10 rating, the power density in the remaining fuel and this 11 gives you less margin in certain transients and accidents.
12 It is not f ree just for a slightly increased fuel cost.
13 There is a balancing of risks also.
We haven't s een an y s
14 detailed analysis. that I know about it.
15 COMNISSIONER GILINSKYs Have you discussed that 16 with the Germans ?
Presumably they have thought about that.
17 HR. MUBLEY Not in detail, no.
The shifting of 18 peak flux and peak power that Steve refers to is accounted 19 f or in the two and a half percent increase in fuel cycle 20 cost because it limits the burn up of the f uel that you can 2100 to.
22 I think we just have to wait until they come in in Z3 sid-January with their final analysis because I have thought 24 I have heard discussions where Westinghouse has told us that 25 there is virtually no penalty f or their low leakage core.
ALDERSON REPORTING COMPANY,INC,
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_ ff, 4
50 1 But I can't say that for sure.
It is just a recollection L
2 that I have of one of these meetings.
3 CHAIRMAN PALLADIN0s A t an earlier briefing I 4 asked why didn 't they go do some of these things like heat 5 the ECCS water and replace some of the outer fuel elements 6 with I will call them dummy fuel elements.
The answer was 7 well, we have got to wait until we get all these 8 calculations before we can see whether or not we have got a 9 problem.
In a few of them we seem to have a problem.
10 Are the vendors of these plants looking at 11 possible solutions or are they so convinced they are so far 12 avar from the problem that they can convince us?
13 MR. MURLEY:
It depends.
We have got quite a
~
14 spectrum of views from the licensees.
I think, as 15 Commissioner Ahearne said, the Duke reply, although ther 16 didn't. agree with the Oak Ridge analysis and report or 17 anythink like that, they have a good understanding of the 181ss ue.
Others, I think they probably see it as another one 19 of NRC 's games.
So it varies.
20 CHAIRHAN PALLADINO:
The reason I think they ought 21 to have interest aside from the problem of the vessel is 22 that it takes time to develop duany elements and put them in.
23
- 53. MURLEY4 That is righ t.
24 CHAIRMAN PALLADINO - If any plant is two to three 25 years away from a possible problem area, they ought to use ALDERSON REPORTING COMPANY. h'C, M
51 1 the two to three years to get out of it.
2 MB. MURLEYa It will certainly prolong the useful 3 lif e, whatever it turns out to be, before they have to do 4 something.
5 COMMISSIONER AHEARNE:
Maine Yankee I thought was 6 taking some action f rom a draft response that had come 7 through in the letter.
We were responding to I think the 8 Governor of Maine and there is a draft that has been 9 around.
My impression was that in that letter the mention 10was made of a couple of actions that Maine Yankee was taking.
11 MR. MUBLEY:
I think they are looking at raising 12 the temperature of the ECC water.
13 COEEISSIONER AHEAB..Es And also I thought modified 14 fuel elements.
Are they addressing this?
15 MR. MURLEY:
I don't recall right offhand what 16 Maine Yankee is doing.
Hight offhand I can't recall what 17 the y are doino, hat we have their reply.
l 18 COMMISSION ER AHEARNE:
I was just answering the l
19 Chairman, that' at least that was one instance I saw where (Inaudible).
20 t hey were going ahead 21 MR. MURLEYa Move on to No. 13.
22 I should just point out to you that Professor Z3 George Sih of Lehigh University has had discussions with the 24 staff.
I believe he also talked with the technical 25 assistants of Commissioners.
ALDERSoN REPORTING COMPANY,INC,
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COMMISSIONER AHEARNE:
Not all of th em.
2 MR. MURLEY:
The staff met with him.
I did not 3 personally but other did, and he has expressed views that 4 the current. methodology might not be adequate for predicting 5 vessel failure correctly.
'The staff is evaluating these 6 comments.
It is a little tough to deal with because it 711terally calls into question the entire ASME Code and the 8 mothods used by the Code Committee, but we are looking at it.
9 CHAIBHAN PALLADIN0s You could take his statement 10 as good news or bad news.
Which side of the question is 11 1 t -- (Inaudible).
12 MR. MURLEY I don't think he has a bottom line 13 that it is conservative or non-conservative.
He just thinks 14 that the methods are not accurate.
15 COMMISSIONER ROBERTS:
Well, who is he?
I mean is 16 he the guru of pressure vessel design?
17 MR. MURLEY:
He is a professor at Lehigh 18 Univeristy, which is well respected in fracture mechanics 19 and engineering mechanics.
I think he generally marches to 20 his own drummer.
I think we just simply have to evaluate 21 what he says.
He has not, as far as I know, been involved n in a lot of the code committees and stuff that we rely on 23 for our regulations.
24 MR. HURLEY:
I will move on 15.
25 The issues that the staff is going to be ALDERSON REPORTING COMPANY. INC, 400. VIRGINIA AVE, S.W " WASHINGTON. D.C. 20024 (202) 554 2345
t 53
~
1 addressing are tough ones like what credit should be allowed 2 for operator action.
The regulatorr limit we already talked 3 about, whether a simple limit on the reference temperature 41s adequate or not.
The industry has told us they don' t 5 think it is, they don't think it is a good limit.
9 Credit for operator action?
How should you do the 7 evaluations?
What are the costs and the benefits of 8 corretive actions?
9 If we decide that there is a limit and that some 10 plants either don't meet it or will soon exceed it, what 11 should be the schedule f or implementing any corrective 12 actions ?
13 I only put these down to show you that it is not a 14 simple matter to come up with a regulatory position today.
15 The next chart.
16 We are virtually certain that there vill be 17 substantial technical disagreement between the staff and the 18 ind ustry on the issues I just showed.
19 The work need to technically resolve it, and by 20 that I mean come to a consensus where people agree on it, 21 von.' t be f ully coupleted by next sumner.
In some cases it 221s going to take probably a couple of years to what I call 23 technically resolve an issue.
24 The next chart, the staff conclusions.
25 These are virtually the same conclusions that we ALOERSON REPORTING COMPANY, INC, 033 MDElE CR$9 @.W, @lN$T@00, @.@. M4 (852) @@$4@
s 54 1 showed you in June.
It is a safety concern for older PWR 2 vessels.
We don't think that immediate corrective action is 3 necessary.
Substantial work is needed.
4 It is the staff's judgment that some corrective 5 action will likely-be required for some of the older plants 6 before their service life.
Now the basis for this staff 7 conclusion is really a risk argument.
8 He have evaluated the number Lf classes of 9 overcooling transients.
The chances of a severe overcooling 10 transient in an older PWR that could challenge the vessel is 11 about one in one hundred considering all the plants and 12 considering the probability of those transients during this 13 coming year.
14 CORRISSIONER GIIINSKYa This is not per plant but 15 f or. tin plants?
16 HR. HURLEY4 For more like 40 plants, PWRs, 44 17 actually.
18 The B&W plants clearly have a higher probability 19 but there are only about seven of those.
20 COHHISSIONER GIIINSKYs Wait a minute.
Is most of 21 tha t concentrated in the B&W plants?
22 MR. HURLEY:
Yes.
23 COHHISSIONER GIIINSKY:
So it is one in a hundred 24 for 10 plants more or less.
25 MR. HURLEY:
Let me throw another chart on that I ALDERSON REPORTING COMPANY. INC, 400 VIRGINIA AVE., S.W., WASHINGTON. D.C. 20024 (202) 554-2345
55 1 think will help illustrate it.
2 Put on 3-5.
3 This is the chart of our best probability 4 estimates.
The most likely overcooling transient is the SBancho Seco type transient "where you lose power supply and 6 you have a control system f ailure.
7 For BEW plants our estimate is that it is ten 8 times more likely than for Westinghouse or CE plants.
There 9 are about seven plants.
So one gets seven times ten to the 10 minus three for BCW plants for the next year.
There are 1130-some-cff Westinghouse and CE plants.
So roughly you get 12 30 times ten to the minus four, or three times ten to the 13 minus three.
When you add those together then one gets 14 about ten to the minus two.
These are in order of magnitude 15 estimates.
16 COMMISSIONER GILINSKY:
So it is nostly 17 concentrated in the B&W plants?
18 MB. MUBLEI4 Yes.
To go with that, although the 19 BCW plants have a more likelihood of having an overcooling 20 transien t, they are not as brittle, the vessels.
That is, 21 they are not as old and they are further away.
You can see 22 f rom tha t table there tha t they are further away fron being Z3 threa tened.
24 CHAIRMAN PALLADINO:
That is because they are 25 younger or is there something peculiar or special about ALCERSCN REPCRTING COMPANY,INC,
56 1 their plants?
2 NR. HURLEY:
They are younger and they also have 3 lower flur generally and so lower fluence.
m 4
You see, Oconee has about five effective 5 full-power years.
That is 'the oldest BCW plant, Oconee 1.
6 I think some of the Westinghouse plants have around ten 7 effective full-power years.
8 Put 17 back on, please.
9 Even if a transient as severe as Bancho Seco were 10 to occur we would not predict vessel f ailure toda y.
So the 11 combination of the chances of a transient being low plus 12 even if it were to happen, we wouldn't predict failure.
I 13 don't have a number for that.
It is very difficult to do a 14 a probability analysis on the f racture mechanics.
We are l
15 doing that.
The research staff has a probabilistic code 16 that they are working on which I think personally will show 17 tha t there is even more margin than we thought before just 18 because it is going to treat things in a statistical way 19 rather than use bounding type numbers for material 20 properties.
21 CHAIRMAN PALLADINO:
Tom, is there any particular 22 date when they sta rted makino vessels with different 23 compositions ?
In other words, are all the plants that are 24 now coming up for licensing, do they all have the same 25 HR. HURLEIs It was about '72 or '74 I think, ALDERSON REPCRTING COMPANY. LNC.
400 VIRGINIA AVE., S.W., WASHINGTON. D.C. 20024 (202) $54 2345
j 57 1 wasn' t it, Ray?
2 MR. KLECKER:
I am sorry.
~~
3 MR. MURLEY:
When did the vessels stop using high 4 copper and when did we recognize the problem?
5 MR. KLECKERs About 1973.
6 MR. MURLEYs About 1973.
So vessels fabricated 7after about 1973 should not have this problem.
I should 8 mention. that there are still a lot of vessels in the mill 9 though.
10 CHAIRMAN PALLADIN0s I know.
I guess what I am 11 really asking in the end is what are those plants where at 121 east on the surface this problem does not seem to exist?
13 Maybe we could get that as a separate answer.
14 MR. MURLEY:
Oka y, sure.
15 CHAIRMAN PALLADIN04 Not that that makes the 16 problem any easier, but just to increase our information.
17 MR. MURLEY2 The last chart, No. 18.
18 As a prognosis the staff can have a regulatory l
19 position by next summer but it involves wrestling with these 20 issues.
21 COMMISSIONER ROBERTS:
How can you make tha t 22 statement in light of the previous statement that says the 23 work needed to technically resolve the issues cannot be 24 fully completed by summer
'82.
25 MR. MURLEY:
That is right.
ALDERSON REPORTING COMPANY, INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024(202) 554 2345
58 1
CONHISSIONER ROBERTS 4 But we are going to issue 2 regulations.
3 MR. MURLEYs Well, th at is a question of what is 4 the perceived risk a t the time.
If we perceive the risk, 5 that is we the Commission perceive the risk to be high we 6will have to have a regulatory position on it, even though 7 ve won't have done all of our homework.
That is the dilemma.
8 MR. DENTON:
Tom, let's put a schedule of future 9 actions that maybe would show what additional information we 10 would have about that time.
11 HR. MUBLEY:
No. 14.
12 EPHI is doing a study on the annealing of vessels, 13 but most 1sportant I think are the owners groups reports 14 scheduled f or December 31st.
15 CHAIRMAN PALLADINO:
Where is that?
16 ER. HURLEY:
It is back about five charts from the 17 back.
I am sorry I didn't number those.
18 CHAIRHAN P AL LADINO:
It would be helpful if they 19 vere numbered.
l 20 HR. HUBLEY:
At the end of the year we are going i
l 21 to get the three owners groups reports, Wes tingh ouse and l
22 Combustion will be generic with some plant specific 23 inf orma tion.
The B&W report will focus on Oconee 1 and 2.
24 Then in mid-January the 150-day resposes will be due.
There 1
25 will be an evaluation of corrective actions in the 150-day l
l ALDERSON REPORTING COMPANY, INC.
CQ VIR? INIA A$ @,W, WC@HIN8T@Ne D.@. M384 (98 @@3-884@
0 59 1 responses.
Also, they will in some cases update their 2 material properties for us.
3 MB. DENTON:
That will address the effectiveness 4 of things like heating the emergency core cooling water or 5 removing f uel on a plant specific basis for the eight plants.
6 CONHISSIONER AHEARNE:
Tom, you said that BCW is 7 going to focus on Oconee 1 and 2 and you just pr evio usly had 8 mentioned the seven B&W plants that were in this high 9 probability region.
Then there is an item mentioned, and I 10 t.hink it was in report of the BCW owners group meeting that 11 rou had here which pointed out that the plants following 12 0conee had additional control system features that led to 13 some of the concerns about Oconee not being valid for those 14 other plants.
15 Are you working into a position here the B&W 16 owners group is not going to allow you to address the rest 17 of those plants?
18 NH. DENTON:
No, not at all.
I wanted to just 19 skin across the top of these plants and not ask all 44 20 plants the first day because I didn't know the right i
21 questions to ask.
So I see these eight as just being the 221ead test plants and we will go back and pick up the others 23 based on what we learn from these.
I don't intend to ignore 24 any of those BEW plants, but I thought it would be 25 suf ficient to deal with the highest shifts first.
l l
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s 60 1
COMMISSIONER AHEARNEa Why was it that the BCW 2 owners group decided to focus upon Oconee, because they are 3 doing more generic -- (Inaudible).
4 MR. HURLEY:
They will be doing the other plants, 5but they won 't be ready by ' December 31st.
I think Rancho 6 Seco comes in like in March and some of the others like TMI 7 follow on.
8 COMMISSIONER AHEARNE:
Are you saying that they 9 reached the conclusion that they could not address it 10 generically?
11 HR. JOHNSON:
Babcock and Wilcox had previously 12 submitted a generic report.
We have had it in our hands, 13 oh, gee, the best part of the year.
Their owners group is 14 going to plant specific as an extension of the generic 15 report they previously submitted.
18 COEHISSIONER AHEABNEs Earlier in the meeting we 17 had been told tha t the analyses were going to be coming in 18 a t the end of December.
Are you saying tha t we already knov 19 the BCW analyses well enough that the questions that were 20 asked ea rlier in the meeting could have been answered l
21 explicitly with respect to -- (Inaudible)?
l 22 ER. JOHNSON:
That was a complicated question.
23 COMMISSIONER AHEARNE:
Well, I will sinplify it i
24 f or you.
i 25 MB. JOHNSON:
Please do.
ALDERSON REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554-2345
61 1
CONMISSIONER AHEARNE:
Earlier in the meeting we 2 were told when some of us were asking questions about when i
3 would we know the actual detailed information which these 4 comments were based.
We were told, well, that had to wait 5until the analyses were exdlained and these analyses were 8 going to be explained in the reports coming in at the end of 7 December.
8 Now what you just said is, howeve r, that we have 9 had the BCW generic report for almost a yea r.
Therefore, 10 you must already understand the analyses the BCW.
11 MR. JOHNSON:
The analyses that are contained in 12 that report, and there is more than one, ha ve been read and 13 generally I think understood by us, but there is a matter of 14 degree of detail.
15 As far as I know, the report was submitted for 18information only.
It was not evaluated in detail by the 17 staff, am I correct about that, Ray 18 MB. K1ECKER:
(Nodding affirmatively) 19 MR. JOHNSON:
--- and what we find in the 20 evaluation that has been done is that were we to do that 21 evaluation we would be turning around right now and asking ZZBabcock and Wilcox for more details which we feel we are Z3 going to get in the plant specific reports.
24 MR. DENTON:
Let me answer tha t.
I don 't think 25 tha t the report that we had originally was adequate and that ALDERSON REPORTING CCMPANY. INC, 400 VIRGINIA AVE., S.W., WASHINGTON. D.C. 20024 (202) 554-2345
62 1 is why we asked for more.
They keep sending in reports.
We i
2 did have a yea.i ago a rather brief summary of theirs and we 3 all read it and said, gee, this doesn't satisfy us.
That is 4 why we gave them more explicit instructions about what we 5 needed.
6 COHHISSIONER AHEARNE:
But you think that the 7 December report even though it is going to focus only on the 8 0conee plants will meet your needs?
9 HR. DENTON:
Harbe there is something further that 10 will have to be done in the BCW plants.
It was the 11 objective to get. these generic reports that deal in depth
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12 with the issue for their type of plants and then provide 13 enough information about each of their vendors that we can
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14 come to some conclusion about that class of plants.
Now if 15 BCW has decided to be exclusive about this we may have to 16 reconsider.
17 That chart though does show that we are not going 18 to get much additional information in af ter about January.
19 In other words, about that time industry will have produced 20 all it has been promising 'and these eight vendors will have 21 produced their site plant specific remedial actions.
We 22 will then have all the information that we can reasonably l
i 23 expect to have for some time.
l Now some people are proposing major research 24 I
25 programs and new looks at fracture mechanics and reopening l
l l
l ALDERSON REPCRTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON D.C. 20024 (202) 554-2345
63 1 all kinds of interesting technical issues.
But I think we 2 will have to stop at that time period and act on what we 3 know because that is going to represent the more or less 4 extent of the information available in the field for some
^
5 tim e.
I don't think we can get.any new information in a 6 short time f rame.
It takes a long time to plan new research 7 programs in this area.
8 CHAIREAN PALLADINO:
Let's come back to the 9 Germans.
The Germans were able to analyze and get their to plant specific numbers and say here is the corrective action 11 we have got to take and they did it in a relatively short 12 period of time.
Now did ther put more manpower on it or did 13 they do something we are not doing or did they just make 14 some arbitrary assumptions and bound their problem and say 15 here is the way we are going to solve it?
16 MR. HURLEY:
Of course the Reactor Safety 17 Committee in Germany is composed of a lot of experts, one of 18 whom is a world 's expert in pressure vessels and fracture 19 mechanics.
20 COEMISSIONER GILINSKYa This is who now?
21 ER. HURLEY:
Professor Kussmahl from Stuttgart.
22 They also only have to deal with one vendor essentially.
I 23 can 't say how it works in this case, but typically they have 24 meetings with the vendors and they come to a technical 25 understanding and the vendor or the utilities decide to make l
ALDERSON REPORTING COMPANY,INC.
400 VIRGINTA AVEL. S.W. WASHINGTON, D.C. 20024 (202) 554-2345
i '
64 1 the change.
2 MR. DENTON:
It appears we are going to have to 3 end up ordering a change if ther occur in the near future.
4 From the year's dialogue we have had with the utilities no 5 one is stepping f orward. to 'make these kinds of changes.
6 They are going to provide the information that we asked for 7in each step on what the impact would be of removing the 8 outer row or heating up the water, but no one, wi th a f e w 9 exceptions, as you say Maine Yankee has been studying the 10 problem for some time ---
t 11 MR. HURLEY Some of the licensees of Westinghouse 12 plants are coming in with their low leakage fuel options.
13 So there is some of that.
14 MR. DENTON:
Maybe some indication. 'I shouldn't 15 say there has been no movement in this area, but not a large 16 movement toward remedial action.
17 CHAIRMAN P ALLA DINO:
I think one of your 18 colleagues has something to say.
l 19 MR. VAGANS:
Milt Vagans, Research.
You mentioned I
20 German several times.
I want to make sure that the staff r
21 completely understands that the Germans and the Finns were 22 not a tta cking the pressurized thermal shock problem, but 23 they were just attacking the problem we had in the 24 degradation of upper shelf material with fluence.
Therefore 25 the problem they faced was normal operating conditions ALDERSCN REPORTING COMPANY,INC,
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t 65 4
1 projected over a period of time and the degrading effect 2 this had upon the upper shelf energy of their velds which is 3 specified in 10 C.F.R. 50.
In other words, it is a 4 regulatory position.
5 So remember they had a lot easier problem than 6what we are addressing.
Normal operating conditions, 7 degradation of materials such that the upper shelf energy of
[
8 their welds in plain material would fall below the minimum 91evel we would like to see.
to COHHISSIONER GILINSKIs But if you are also 11 EArried about overcooling doesn' t that give you an added 12 incentive to go in that direction?
13 HR. VAGANSs Absolutely.
The problems are linked.
=14 COHNISSIONER GILINSKY:
In other words, ther s
15 responded to what they thought was a lesser problem.
16 MR. VAGANS:
Right.
l 17 COMMISSIONER GILINSKY:
And even so when forward 18 and took these measures to slow down the degradation of the 19 pressure vessel.
s.
20 HR. VAGANS:
That is correct.
21 CONNISSIONER GILINSKY:
This is kind of an a s
22 fortiori argument it seems to me.
If they did it for that, w
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23 they certainly would nave done it if they were worried about
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24 ove rcooling.
25 CH AIRMAN PALLADIN0s Tom?
I ALDERSON REPORTING COMPANY,INC, l
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66 1
CONNISSIONER B0BERTS:
Are these Section 3 ASHE 2 Code vessels?
3 COMMISSIONER AHEARNE:
Yes.
4 COHHISSIONER ROBERTS:
What does the ASME Code 5 have to say about this?
Do'n ' t ther have an ongoing pressure 6 vessel committee that refines their requirements?
7 HR. HURLEY:
That is a good question.
8 COMMISSIONER ROBERTS:
I think one of your 9 colleagues is trying to answer.
10 IfR. JOHNSON:
As part of Task A-11, which was the 11 upper shelf program, we had some of the best advice we could 12 get from the ASME Pressure Yessel Code.
To name one 13 gentleman who contributed quite a bit, and you will find it 141n NUREG 0744, Bill Cooper, from Teledyne Engineering l
l 15 Services, points out that the Design Code, Section 3, deals l
l 16 with normal and upset, that would be level A and level B, 17 but does not give any guidance for the accident conditions, 181evel C and level D.
That is written and you will find that l
191n one of the appendices to NUREG 0744 written by Bill 1
20 Coo per.
l l
21 Now Section 11, the part of the ASME Code that 22 deals with in-service inspection, does take that into Z3 consideration but that is af ter one finds a flaw and has to l
24 evaluate it.
Having found the flaw, then one evaluates it 251n the light of the transient or the accident loads that ALDERSCN REPORTING COMPANY, INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554-2345
67 1might be imposed on it.
2 So I am not really sure where you are coming 3 f rom.
If you are talking about Section 3 design, accidents 4 aren 't considered.
If you are talking about Section 11, S inspection, then a flaw has got to be found first.
So there 8are balances to be achieved here.
7 MR. DENTONt I don't have an official ASHE view on 8 this.
9 RR. 3URLEY:
In a nutshell, the Code doesn't speak 10 to overcooling transients.
11 COMMISSIONER ROBERTS:
Obviously.
12 COMMISSIONER AHEARNE:
Let me follow that up a 1311ttle bit more.
Is.the ASHE Code Committee doing any work 14 on this particular issue?
Is this now something that has 151ed to a concern on their part?
16 MR. JOHNSONs You get a qualified yes for that, 17 Commissioner Ahearne, I think.
I have got another who says 18 no besides me.
19 HR. RANDALL:
Not to my knowle,dge.
20 (Laughter.)
21 CHAIRMAN PALLADINO:
A categorical no.
22 MR. MURLEYs I really don't think, if I may, I 23 don ' t think that they are really up to speed.
I think the 24 NRC staff here is ahead of most anybody on this matter 25 because we have had to be over the last year.
i ALDERSON REPORTING COMPANY. INC.
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1 MR. HEHICK Tom, I have a question.
Am I correct 2 that the small break LOCA is limiting in some reactors?
3 MB. MUBLEY:
Westinghouse tells us that for some 4 of their plants small break is limiting, yes.
5 MR. REMICK On y'our supplement slide, I think it 6 was B-5, you did not show small break LOCA.
Do you kncv 7 what those would be?
8 MR. MUELEY:
Yes, I have those.
We estimate the 9 probability of a pressurired overcooling event from small to LOCA to be one times ten to the minus five.
Those, by the 11 way, are in the staff 's response to the Oak Ridge report.
12 There is a complete discussion.
13 HR HEHICK:
That would apply just to the 14 Westinghouse plants?
15 MR. MURLEY:
Only a few Westinghouse plants.
16 MR. DENTON:
I think to conclude this, we are 17 today about where we were in the middle of the summer.
We 18 think action will be necessary on these vessels which have j
19 shif ted the most.
We thought at that time that we had 1
20 enough time to gather the information from a class of them l
l 21 to help us make a more rational decision.
The clock has i
22 been running and they have been working on these.
When they 23 come in I would propose we meet early next year after we 24 have had a chance to assemble those comments together, 25 unless you feel the need for f aster action.
l ALDERSON REPORTING CCMPANY,INC.
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69 1
I think, too, the ACRS is meeting in December, as 2 shown on this chart, to go over the program.
They have 3 generally supported the approach we have taken to try to 4 develop as much information as could be reasonably pulled 5 together from existing know' ledge.
6 Any attempt to refine this technology though will 7 clea rly run us past the decision dates that we are talking 8about.
On this schedule we will have all the technology and 9 research results that are available.
It sounds to me from 10 t alking to the staff that attempts to f r.rther refine this in 11 terms of metallurgical understanding would really. move it 12 out in time.
13 COMMISSIONER GIIINSKY a If at that time there are 14 strong differences between you and the owners, I guess I 15 would like to hear from some of the owners.
16 MR. MURLEY:
Yes.
This could very well be like 17 ATUS where the staff had one view of the risk and the 18 utilities had a different view and it has led to a stalemate 19 for all these years.
I hope it doesn't turn out that way in 20 this case.
21 CHAIRMAN PALLADINO:
Now while we are studying the 22 problem I gather there is no problem in your mind with a 23 Bancho Seco event on some of the older plants, or. is there?
24 HR. HURLEY:
No.
25 MR. DENTON:
Not on any plant today a Rancho Seco ALDERSON REPORTING COMPANY,INC, 400 VIRGINIA AVE S.W WASHINGTCN, D.C. 20024 (202) 554-2345
70
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1 eve nt.
2 CHAIRMAN PALLADINO:
You don't see that as a poin t 3 of concern for several years on the Rancho Seco event.
On 4 the other events you are going into a much more improbable 5 set of circumstances than l'f you rely on operator action to 6 any degree.
I gather that is the basis for some of your 7 confidence that we have no concern at the present time.
8 ER. DENTON:
Proper operator action would certain 9 ameliorate it.
10 CHAIRHAN PALLADINO:
Well, we have enough time to 11 look at it.
12 ER. DENTON:
Yes, we have enough time to look at 13 1t.
I still think that for some class of vessels remedial 14 action is going to be necessary.
15 CHAIRMAN PA1LADINO:
I am looking at it while we 16 are study it.
I want to have some feeling of confidence 17 myself and I as sure all of us want to have confidence that 18 there is no likelihood of any of these vessels going in the 19 time period tha t we are studying.
20 ER. DENTON:
That is where I have come out.
21 MR. HURIEYs Yed.
As I said, we feel we have got 22 time to wrestle with these issues and come up with a 23 regulatory position that can be defended.
The way we are 24 headed now it will include a limit of some kind and it may 25 well mean that some plants vill have to take corrective ALDERSCN REPCRTING CCMPANY,INC.
400 VIRGINIA AVE, S.W WASHINGTON. D.C. 20024 (202) 554-2345
71 1 action before the end of their service life.
I don't know 2 what that means, but it involves some plant changes that c'^
3 could be costly.
4 COHNISSIONER ROBERTS:
Well, what form would they 5likely take?
8 HR. MURLEY:
Well, to remove fuel, but all that 7 (oes is slow down the problem.
But removing fuel and 8 putting in dummy fuel elements on the outside is one 9 example.
Another and the most radical one is to annea'4 the 10 vessel at high temperatures and that has never been done 11 before on a commercial plant and it would be a majcr 12 u ndertaking.
13 COMMISSIONER AHEARNE:
Has it been done on a
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14 non-commercial plant?
15 HR. HURLEY:
Yes, it was done in a military 16 reactor in Alaska.
They only raised it up to 650 degrees 17 Fahrenheit using pump heat, and one only gains like a 50 18 degree reduction in reference temperature by doing that.
So 191t is not very useful.
20 CHAIRHAN PALLADIN0s But if you get reductions in 21 rates of nine or numbers like that it could be quite useful Z2 over the remaining lives of some of these reactors.
23 HR. HURLEY:
Yes.
24 CHAIRHAM PALLADINO:
Well now the next time, and I 25 agree with the request, and I forget who made it, one of my ALDERSON REPORTING COMPANY,INC.
GS VIR@lNIA AVL S.W WASHtNGTON. O.C. 80024 (2023 554 2345
72 1 two colleagues here, tha t perhaps we ought to hear from some 2 of the owners groups' representatives on this.
I think that 3 would be a good idea.
Why don't we take that under 4 advisement and we vill work out th e way 'for doing that.
5 Any other questio'ns or consents on this subject?
6 (No response.)
7 Thank you.
8 We will stand adjourned.
9 (Whereupon, at 3:20 p.m.,
the mee ting adjourned.)
10 11 12 13 14 15 16 17 18 19 20 21 22 23 w
24 25 ALCERSON REPORTING COMPANY,INC, MO VtRZINIA AML 93 Wm EGHINST@Nm b].@. K5F4 (Rifa 993-M
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'7UCLZAR RETA9RT CDM.SSICN This la Os.Mif7 that the attachec pr:Cdecings '::efers the s
COMMISSION MEETII;G 10 the 3atter Of; Briefing on Pressurized Thermal Shock
- CaC4 Cf ?rcceecing:
November 24, 1981 CCCNSC licQLber
? lace Cf ?rOceedir.g:
Washington, D. C.
'4cre '.*. eld as h er eis a p p e ar s, acc cha this is the cet;1:2 1 : : a n s e :- i - g" therecf fc.- the file of the C==::issicc.
Marv C.
Simons Cfficial Reportar (Typed)
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Official Repcc:er (Signat.:re)
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