ML18114A833

Transcript of 790502 Briefing on Steam Generator Denting & Replacement,Held in Washington,Dc.Pp 1-69

ML18114A833
Person / Time
Issue date:	05/02/1979
From:	Gilinsky V, Hendrie J, Kennedy R NRC COMMISSION (OCM)
To:
References
REF-10CFR9.7 NUDOCS 7905220079
Download: ML18114A833 (72)

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NUCLEAR REGULATORY COMMISSION PUBLIC MEETING BRIEFING ON STEAM GENERATOR DENTING & REPLACEMENT

. Washingt_on ; D

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• _Wednesday, May 2, 1979 Pages 1 -

69

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• 1--ctoBI 'l-OZJ Of Telephone:

(202) 3.47-3700 ACE* FEDERAL REPORTER~, INC.

Official Reporters 444 North Ccpitol Street Washington, D.C. 20001 NATIONWIDE COVERAGE* DAILY

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This is. an tmofficia1 transcript of a maeti"ng af the Uni tad States Nuclear Regulatory Cor.mtission he1d an Wednesdav, 2 !vf.av 1979 in tha Commission 1 s affic;S at 1717 H Street, 1'1e ~-!., \\*:a.sai::gt.an~ D. Ce The

• 1 meeti.ng was open to pub1 i c a ttsndance and obser,atian.

Tni s trar:script has not been revie~*,ed, ccrrectad, or edited, and it may contain inaccuracies.

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. The transcri::,t is intended solely for genara1 informatiana1 purposes.

As provided ~Y 10 CFR 9.103, it is not part of the foT"wa1 or infor.;-:al

• record of dscision of the matters discussed.

Excro_ssians of ooinion in this transc:"'ipt do not necassariiy reflect fina1* ~tarmina.ticns or beliefs.* :10 p1e:ding or ot.~er pap~r may be fi1sd v"i"th tha Coiiiiitissicn in.

any proce2dir.g as t.,a rssu1 t of or addr~ss-:d to ~ stat=~snt or ars:1mant contained her:in, except as the Commissi i:m may aut:Iori ze.

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,ce-Federat Reoo_rters, Inc.

25 UNITED STATES OF Ai.'1ERICA NUCLEAR REGULATORY COMMISSION PUBLIC MEETING BRIEFING ON STEAM GENERATOR DENTING & REPLACEMENT Room 1130 1

1717 H Street, N. W.

Washington, D. C.

Wednesday, May 2~ 1979 The Commission met, pursuant to notice, at 9:50 a.m.

BEFORE:

ALSO DRe JOSEPH M. HENDRIE, Chairman VICTOR GILINSKY, Commissioner RICHARDT. KENNEDY, Commissioner PETER A. BRADFORD, Commissioner JOHN F. AHEARN~, Commissioner PRESENT:

~essrs. Chilk, Grimes, Scinto, Eisenhut, Gossick, Snyder, Moe, Bickwit, and Murray.

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14 P R O C E E D I N G S CHAIRMA.i."1' HENDRIE:

Why don't we go. ahead?

It may be some time before we get.the rest of the contingent here.*

The subject_ this morning is denting in steam generators and steam generator repai,rs.

Lee, go ahead.

2 MR. GOSSICK:

Okay.

Mr. Eisenhut will give the briefing, Mr. Chairman.

MR *. EISENHUT:

Thank you.

What we'd like to do is start with somewhat of an overview 1:>ackground of where we've been on the denting problem~

As you recall, we briefed. you. a *couple of times II 15 over the last coupie of years, so I'll.just try to go. throu;*h * *.

16 17 18 19 it in somwhat of a summary fashion.

What I' 11 do is I' 11 go through the *background_*.

history of denting in summary fashion, and then I'll specifically address the Surry history, and then we'll discuss the Surry safety evaluation and environmental impact 20

1. appraisal that they have done..

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I I The NRC really got involved in the denting

• reviews I think in about the summer of '76 when we were notified of this phenomenon, and at that time denting was be.lieved to be basically pretty minor and was believed to cllct:* 9ede1:al cRepo-rte'l:J,.§nc.

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3 affect a small number of plants, like about a.half dozen.

2, That was*during the summer of '76, as I said, 3

and in about September '76, I believe it was September 15, 4

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there was a sudden leak developed at the Surry reactor. It was an 80 gpm leak in Surry Unit 2.

COMMISS.IONER KENNEDY:

Eight zero?

MR. EISENHUT:

Yes.

80 gallons per minute, very sudden. It appeared like an instantaneous break.

That was the second time that there's been any leakage in steam generator tubes of any significance.

The 11 -

first had been a year or so earlier at a Point Beach reactor 12 where there was a 125 gallon per minute leak that appears 13 14 15 16 17 18 19 20 21 22 23 24 25 to have been attributed to the classicai wastage problem.

• With t~e September leak in the_~urry steam generators--

COMMISSIONER KENNEDY:

Is 125 gpm within t.'le

.normal bounds, do you know?

MR. EISENHUT:

The *maxir.tu.."n theoretical on a steam generator tube is probably somewhere in the order of four or five hundered g:pm _from a double-en<Jed.offset, to the extent it can offset.

• Most leakages otherwise were down on the order of a couple of gpm.

I mean that was in fact the larger of the ieaks *. Many of them* were down on the-order of gallons.

per day, essentially very small l.eaks.

dl-c~- 'Jede,:a_/ cRepo,:te'rJ, !lnc.

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CHAIRMA.1'1 HENDRIE :

But*, see, in tech spec limits they're very typically what?

MR. EISENHUT:

Maybe in the order of anywhere froml to 10 gallons per minute would be a tech spec on shutdown~

• And. as you' 11 see a little later when we go through it, we have in fact put down the tech specs from these plants as a result of that.

(Slide.}

. The first slide is simply a cartoon to orient you where we are on the steam generator and what we'll

• really be talking about*is the.steam generator tubes; The inside of the tube is the primary circuit.

The outside is the secondary side *.

• This is a typical PWR where.. you can -- wi t:i U tubes. *. B&W reactors have once* through.* The tubes go

• essentially from the top to the bottom, instead of making an inverted U shape.

• (Slide.).

The. next slide is a closeup of a typical PWR steam generator.designed by Westinghouse that we'll be discussing today.

You can see the U tubes, which is~ bundle of perhaps 3000 tubes per steam generator -- excuse me --

15 0 0,. I believe, on a Westingh,ouse plant.

And you ' 11 see s.everal plates going acres~, labeled ~upport plates, tube c:llce*. :l-ede,za/ cRepo'l:ti:,z~, !lnc.

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supports.

These are about 3/4 inch carbon steel plate~.

Basically it's a conglomeration of different arrangements.

The anti-vibration bar is at*the top which holds the bundle in a rigid sense while the coolant is going in one side and out the other side, which has a baffle in the lower head.

So, therefore, there's a hot side and a cold side.in that lower channel.

It's important to realize that those tubes are in fact part of the primary coolant pressure boundary and, in fact, comprise like about half of. the surface -- over half of the surface of the primary coolant pressure boundary.

They are important from a safety standpoint for a number of reasons.

First is, if you have leakage from the primary side to the secondary side during normal operations, you can get radioactivity in whatever form it's there in the primary coo~ant inventory out to the secondary side.

There is also some concern that if you'd have degraded steam generators -- that is, degraded tubes~- to the point where they're on the verge of failure, and _then given a main steam line b~eak or a LOCA it would put a rather sudden loading on the steam generator tubes.

In a main steam line break the outside pressure would go from essentially 1000 psi to something much smaller, with the inside at 2000.

Therefor*, the differential pressure dl-ce- ~ede-r:a/ c.Repo1:te1:j, 2nc.

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1 I. increases *

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I Conversely, for a LOCA the inside pressure of 3

2000 psi is greatly reduced, while the outside is at 1000 4*

psi.

So* it inverts the delta-T.

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I The next slide --

(Slide.)

-- shows you what.is really called.the denting phenomenon.

These are the support plates which are about 3/4 inch carbon steel plates, wi;h a tube so~ething like about 7/8 inch in

.I diameter.

The tubes are made out of.Inconel-600.

What has been happening is you get a situation where yoµ *have an acid chemistry in the little crevice between the tube and suppor:t plate.

An acid solution in the presence of chlorides causes corrosion of the.carbon stae.!. support.plat~.

What it does isit creates Fe3o4, which is iron magnetite. It volumetrically expands upon corroding away the plate, and, in fact., it expands about 2 to l.

It's a very hard material.

As the material grows or expands due to formation of more of the material, it literallz crushes down the tube, thereby denting.the tube *.

COMMISSIONER BRADFORD:

If. you had a tube, a set of.tubes, in which denting was a significant problem, and then you had a s.et of events that began like the Three Mil.a Island accident, that is, you boil the steam generator dl-ce* ":lede1:al cRepo-:ta4, !lac 4'4' NORTH CAPITOL. STR!UtT.

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• 24 25 II dry, what would you expect to see happening in a steam generator like that?

7 MR. EISENHUT:

The general approach has been to remove from service by plugging those tubes in a degraded

.mode.

So, therefore, our approach has been to stay ahead of the degradation and, as a matter of fact, try to predict what*' s going to happen* in terms of degradation and remove the tubes from service before they degrade such that you don't really have degraded tubes "that have primary coolant going through them at any time.

So that you wouldn't really have situations that have been avoided by preve~tive plugging ahead of time.

COMMISSIONER BRADFORD:

So you'd plug not just the tubes that a=a actual.ly leaking --

MR. EISENHUT:

That's right.

COMMISSIONER BRADFORD:

-- but the ones that are showing some degradation?

MR. EISENHUT:

Yes.

And. you'll see that in just a.little while.

There's a plugging criteria which says that if the plant is going to operate for six months, we look at how things have been degrading historically in*the plant, and then we have a very conservative plugging pattern that requires a considerable number of tubes to be plugged to justify the.six months operation.

COMMISSIONER AHEARNE:

Darrell, what's the die~- r:1-ede-ral cRepottte'tj, ifnc.

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8 thickness of the tubes?

MR. EISENHUT:

I don't remember.

Does anybody remember?

CHAIP.MAN HENDRIE:*

40 to 60 mills, you'd guess?

MR. EISENHUT:

Well, you can see, it looks --

well, the gap is 14 mills.

I'm just not aware of that, I'm sorry.

But anywhere from 40 to 60 mills. It varies somewhat as to the design of the tubes.

MR. SNYDER:

Darrell, can I interrupt and put a question?

How much in the way of excess tubing is there installed in the typical -- how much.flexibility do you have?

MR. EISENHUT:

A considerable amount.

And you' 11 s,ie

• as we go t:.llrough here a c;ouple. of tha.steam generators the steam* generators at. Surry are about 21-1/2 and 24-1/2 percent plugged today, and they can still operate at full power.

Probably 30 percent excess~

So there's a 19 considerable amount of excess tube surf ace in the steam.*

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_generator.

. 21 22 23 24 25 All right.

The answer is 50.

The next slide. --

(_Slide.)

is a summary of problem areas that we have encountered in steam generators, sort Of all the effects put together dice- '"Yede1ra/ d?epo'l:te'!4, 2rzc.

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4 in one place *

• And also let me apologize for not having handouts.

We just pulled all these together in random disorder this-mol;'ning, and that's why the numbers don't correspon:d.

They've been taken from a number of places.

9 s I Most of these slides appear in a summary report on the steam I.

s I generator experience which we sent out in January of this 7

year.

8 j Up in the upper left you see the denting phenom-9 __, enon

• graphically displayed, where. you can see what's 10 I actually happening to the tube.

11 The tube, as it's-crushed down, becomes very 12 much of an irregular shape.

In those little areas that 13 I are indented quite often leaks develop.

14 I. through the wall in the tube, and when they *do that most Cracks develop 15 16 17 18 19 20 21

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often they*are in-the region shadowed by the support plate.

That is*, they' re within t,hat substance and therefore not as open to the primary to secondary leak, and therefc:>re they're very small because they have to leak through that medium.

COMMISSIONER BRADFORD:

Are all -PWRs susceptible, or only those with curving tubes?

MR. EISENHUT: I'll get to that in just.a moment.

The only ones that have had denting_ phenomenon are those with U-tubes; both."Westinghouse and CE.

And itis tied to the support plate design also, while I'll run-by in just a die~- r:lede1:a/ cRepo'!te1:4, *!lac.

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5 I 6 I 7 I a I 9 I 10 11 12 13 minute and try to differentiate the different kinds of CE reactors.

On the lower leftis a picture of the support plate.

The big.holes may be the coolant holes, or vice versa, in the diagram.

In one instead of the holes are tubes, the other are coolant holes.

10 As the forces are squeezing down the tube, there's also an equal amout of force, of course, on t..~e plate, and the plates are cracking.

When th~y crack -- we've seen actual areas where you have a little cracked area, such as the shaded area, where it'.s cracked, the little small area between the coolant channel.* and the tube.

As the plates are cracking and distorting, the 14 II flow slots -- there are six of t!:asa across the micdla c=

15 16 the support plates, about 18 inches across.

They do what*

is shown pictorially in the lower right.

That is, they 17 bec~me hour-glassed~

18 I' 11 have another picture of this in* just a 19 moment.

2o Because the plate is being.cracked *and distorted, 21 the 9late is actually deforming.

• Since the plate is.

22 deforming, if you look at the flow slot on the very upper 23 support plate you see that.-- on the inside of this bundle

. 24 there is some tubes that* go. up and make a very

• tight indent, 25 so to speak, at the very top.

The legs are only about five dice-r:l-ede-raf cRepo,:te'l~, £Inc.

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11 inches apart across the flow slot.

The flow slot. is about 2-3/4 inches across.

You can see up in the upper right.

view what happens is the legs of the a-tube, at the very inside there, are_pulled together, which causes the ovaliza-s I tion of the tube at tye top, which yields to higher stresses in the tube, which yields to cracking problems on those 6

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• I 9 I innermost tubes.

The 80 gallon _per minute leak at Surry that developed in September. of 76 was,.in fact, about a 4-~(2 10 I* inch long crack, 4-1/2 inches on the outside, *at. the top of

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20 21 22 24 25 the U bend.

I think it's on the inside of the U bend that stresses are higher than on the outside.

These are basically the types of major problem areas in PWR steam generators from the denting phenomenon.

There are a couple of others.

There are loads being trans-ferred from the support plate to the wrapper, for examp~e.

They are somewhat secondary concerns.

The next couple of slides --

(Slide.)

This slide visually*shows you some of th.is.

This is actually taken from a.CE reactor, a Combus:tion Engineering reactor.

Combustion Engineering support plates are.not in general the solid support pla~e like Westinghouse's throughout.

They do have in the upper portions of the u bundle, they have partial support plates.that are solid.

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• . 19 20 21 22 23 24 25 12 This is actually a picture of one, and you can actually see on the.outer periphery of that support plate, on the outer periphery_of the bundle, you can actually see a crack in the support plate, which graphically shows -- visually shows, at least, actually what's happening.

(Slide.)

The next slide is a photo ~aken from -- and you can see actually down through two support plates --

actually showing the hour-glassing, as we call it, of one

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of these rectangular flow slots that are about 2-3/4 inches across and 18 inches.long.

And you can actually see how they're expanding.

• Now there is some concern, of course, as these expand on the L"l:iermost

• rows of tubes there I s always t!"le concern as to whether a small piece will break away to the point where tubes will be free to vibrate.

(Slide)

• The next slide is still.one more photo showing in the upper photo you can see what's happened, and you can see this is the edge of one of the partial support plates from *a CE reactor, and* this is where it cuts across the outer corner of the bundle.

And you can see where it's actually-cracked and pulled apart.

(Slide.)

The next slide is a summary of the experience df.ct:- ":f de'laf cRepcntt!'l~,.£Inc..

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II 14 I 15 16 17 18 19 20 21 13 that we've had on CE, and Westinghouse steam generat*ors.

This slide is sort of a this is the status as of October 1978, sort of a*summary of all the proble.'Ils that are out there that we're working with.

The first column, wastage, is a phenomenon where you're*basically getting to wearing away or erosion.of tubes, corrosion of tubes. It's basically a problem that historically had been here back in the early 70s, associated with sodium phosphate secondary slde treatment. It is a treatment that was used to help reduce the amount of scale buildup in steam generators on the secondary side.

Basically, the other problem deve_loped after the fix was put in for wastage.

Most of these p*lants converted from wastage to all-volatile t=eat.'nent ~

Wheri they put in all-volatile treatment; something on the order of 4 months to 14 months after that they started to see the denting problem.

COMMISSIONER AHEARNE:

1'1hen you say put in all-volatile treatment, what does that mean?

MR. EIS~NHUT:

They put in a*--*it's basically a different chemical control on the se~ondary side that

. doesn't utilize sodium phosphate. It's a --

22.

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COMMISSIONER AHEARNE:

What did they use?

24 25 MR. EISENHUT :.

• Do you: know what they are, Brian?

Well, there's a couple different kinds of controls that are atf.ce * '3-ede,ra/ c.Repo,rte'r:!, !Inc.

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1 jused.

Basically the approach is to go towards the zero 2 I solids, so that you are not leaving heavy stuff around in 3

the secondary. side.

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COMMIS9IONER AHEARNE:

Does it add, then, chlorides.

MR. EISENHUT:

No, it does not add chlorides.

6 That's an important*consideration.

I'm sorry. It did not I

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• add chlorides.

Chlorides can come from any number of ways.

a In fact,it's not just sodium chloride, it's any kind of 9 I chlorides that can get you in trouble *.

• 10 11 And if you look at a cross matrix of these to the cooling source_that they're on, iou see.the more 12 1 brackish water they'"re**on some of them have bigger problems.

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. ; So we tried to look early in* the game for a

• 14 I correlation between -- =or e:-::arnple, if t..~e :i.J:'Oblsm is only showing up. at plants that have a. lot of salt water on t..l-J.e*

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23 24 secondary side or on the tertiary side *. And it. turns out it's not completely that clean.

It's probably tied to the degree of true denting and to the time it takes to get to true denting.

However,.

even trace c11Uounts of chlorides*on the secondary.side can get you in trouble.

COMMISSIONER BRADFORD:

How long does it seem to take for denting to first show up?

MR. EISENHUT:

To first.show up it appeared to be

25. anywhere from 4 months to 14 months after' conver'sion from cllce- :3ede1:al cRepcnte1:~. !Inc.

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7 12 13 14 15 16 17 18 19 20 21 15 sodium phosphate to all-volatile treatment.

CHAIRMAN HENDRIE:

Is there a PH change in the secondary water?

Doesn't the phosphate leave it slightly on the acid side?

MR. EISENHUT:

There is a chemistry change associated with those.

I'm not sure exactly what that is. -

We do have a detail of that. It's just that I don't happen to know it. I'm not familiar with it right now.

We can it was tied to PH on the secondary side~

We extensively went through this about a year.ago; as to the PH.

The numbers escape me..

To give you an ide~ of these plants that were initially -- that back in '76 had the most ex~ensive denting, the six plants we had at that time were-the Surry-1 and 2 steam generators, which are on a brackish coolirig water mode, Turkey Point-3 and 4, which are on sea watef, San Onofre-l, which is on sea water, and Indian.Point-2, *which*.

is on brackish water.

Those are the ones-that we really had at that time of great concern.

Later, as time went'on, other plants,however, developed denting *

.And if you look at some that are modern, 22 for example, Ginna is on a fresh water lake, _Connecticut 23 *

• Yankee is on a fresh water river, Robinson is on a fresh 24 25 water source a la'ke in that case.

What we basically tried to do from the period dtc~- (jede-ra/ c:Repo-rte-r4,

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16 of time from 76 and 77 was-we tried to look for some kind of a correlation as to what was really causing true denting.

And I'll mention a little bit, there are extensive studies underway in the industry to try to duplicate denting in labs, and they've been able to do it very easily.

Basically, it's tied to an acid solution.

If you can have an acid solution and have chloride ions present, you can get denting. It's just a matter of time.

MR. SNYDER:

Does it require carbon steel as the support?

MR. EISENHUT:

Yes, it reacts to form Fe3o4 which is the carbon steel.

COMMISSIONER AHEAR..~E:

Al;'e all these steam II generator tubes Inconel?

[

MR. EISENHUT:

• Most of the ones we're talking about here are Inconel. That's the standard --

COMMISSIONER AHEARNE:

Does it hui:t stainless as well?

MR. EISENHUT:

• We haven't seen it on stainiess steel tubes, but I don't think any of these plants have stainless steel tubes. It may eventually. It's just a matter of time.

I.f you had stainless steel. support plates--

and you'll see this when I get to it in a minute ---that i"s one of the.things you would put in to help cure the problem, or certainly *greatly_ reduce* it. If you had stainless' steel dl-ce- ~edaa! cR~po,rtett~ *.!lnc.

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s I 17 support plates other things you can do is change the support plate design so you don't have the crevice with flow going

'through the hole, you would have the flow going right between, through the crevice, literally.

So there fixes that you can avoid the problem 6

somewhat in the absence *of a*complete understanding of all 7

related phenomena th.at are going on.

a On this slide I'll also mention you can see the 9 II. things I mentioned on the right *. Under the general heading I

10 of denting, there's denting,the hour-glassing, the*islanding:-.L 11 that* s when a small piece along an hour glass breaks loose.

12 Leaking dents.have been observed in a* few plants.

13 There's a question mark beside Point Beach because we're 111 I not sure, because the tube was never gone in and looked at II 15 i and *removed to see whether or not it was from wastage or 16 17 18 19 21 22 24 25 from denting.

-A couple of the.plants have actually -- several of the plants have actually cut holes in the side of the steam generator so they can have a port to look through, a small hand hole to send in cameras *. Others, namely Surry and Turkey Point, have actually gone*in and.removed*tubes.

at support p_late interfaces.

MR. SNYDER:

What does the table say about Yankee Rowe and Zion?

The%'.e doesn't seem to be any entry after tube -denting.

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Yankee Rowe, it says they do not have it. The ones that don't have x's, it's not shown up yet.

Now, the CE reactors at the top, most CE reactors, as I said, do not have a design that has the tube holes and the coolant holes separate throughout the steam generator.

They only have them from the upper regions of the steam generator on sort of the sides, where the U tubes go up.

They go up, and they're essentiaily rectangular at the top, as opposed to the U bend.

They have them at two levels in the ~pper region, partially.

One of the CE steam generators does have solid support plates, but the current de~ign is to use somewhat what they call an egg-crate design, just cross members or lattice work, so that the coolant flow on the secondary side flushes around the tube at the support plate.

The basic approach, as we started to see tb.i s in 76 and 77 and 78, as we started to see more and ~ore degradation of.steam generator tubes *in various modes, has been to

• require more in-service inspection a.t

• shutdown. It gives us more confidence that the plant is safe. It also gives.us more information to be looking for along.the line.

• we require when they shut*down that *they under-*

take a preventive plugging.pattern.. That*is, they go in

... and they do an* eddy current inspection of all the tubes in c4ce-c:Jede-ra/ cRepo-rte-r~. !lnc; *

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I ii 19 suspect regions. If you find a tube that does not pass an eddy current probe of various size. -- they use various different sized probes -- if you find one that doesn't pass it, you therefore plug that tube, and you plug the next two tubes 01,1t in all directions from it, thinking that if that's an area that is vulnerable because the support plate is crushing or cracking, we want to plug the tubes in that general area -- a quite conservative approach.

Initially it was to plug the adjacent tubes_ *in.all directions! and now

-it's plug the two adjacent tubes in all directions, because the denting phenomenon is associated with sort of the. hard spots in the support plates. That is, where it can't give so much.

You can generally find that it's two places *. One is most of the denting, bad denting, and the.leakages has been along the flow slots where there are solid pieces.

between the flow slots where the plate cannot give, and. at the outer periphery where there are hard spots that, again, do not have.holes.

The amount of denting is highe~ in those regions.

That is, the plate ;elieves itself.

Also, based on these inspections we required a limited amount of operation.

That is, we didn't give them on a severely degraded plant we didn't give them from refueling outage to* refueling outage.

We basically.gave them anywhere from four months to six months operation, at which point they' 11 have to shut the plant back down* and do.

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ii 20 another inspection.

We had it on four months or six months, and somewhat less lately on a couple of plants, because we didn't have enough data on how fast denting was proceeding.

We didn't know whether this was a phenomenon that was really going to turn bad in a very big hurry --

we had.limited data, I should say, so, therefore, we had a limited amount of time.

We_put on strict leakage limits.

We reduced the primary to secondary leakage limit that required.

shutdown down to about.3 gpm.

That.is, if you saw one leaking tube from primary to secondary of about.3 gpm, that limit or higher, you'd have to shut the plant down and go.in and do an inspection~

That was a conside.ra.ble reduction.; *These plants I think had al gpm leakage before.

COMMISSIONER AHEARNE:

Is thE;! onlY'., then,. method of detecting if there i~ denting problem during operation, leakage?

MR. EISENHUT:

Yes, that's basically right.* And that's why you have to do very extensive inspections when you shut the plant down.

We also put on them a couple of other things.

One was a multiple tube leakage requirement.

That is, if you can see degradation at more than one tube in any short period of time, then in light of this cllce-r:l-ede,za/ c:Repo1:te'l~, !Inc.

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20 21 22 23 24 25 21 conservative plugging pattern you can say that things are not behaving as you would expect.

So we said any two leaks in 20 days, the plant should come down.

We put that on, I believe, in late 1976 or early 7 7 by order*.

And, in *fact, we have not seen that situation, on 2 in 20.

Well maybe we-~ well; if we have, we've just seen it once *.

I don't believe anyone has shut down because of that threshold.

They have*shut down because of the.3 gpm limit.

We also put limits on the primary coolant system inventory which they're allowed to continue to operate with, so that we reduced those limits down to basically the standard tech spec limits so that*if you should have a leak a smaller amount or activity will escape from the primary to secondary side.

Those are the short-term things we've put on the extensively degraded plants, as we call them, extensive denting.

There's a*certain number of longer-term efforts, of course, that began about the same time and are underway~

• COMMISSIONER BRADFORD:

Darrell, on that slide is denting synonymous with degradation? After that note 5 it applies the word degradation to at least 3 units tb.at

.I wouldn't have thought had U-shaped MR *. EISENHUT:

Yes.

This slide was originally --

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COMMISSIONER AHEARNE:

It's the*B&W's.

MR. EISENHUT.

Yes, it's the B&W's, but the B&W's were deleted from the slide, so I think that may be a carryover.. note.

The slide originally had CE, Wes.tinghouse, and B&W on it, as all of the steam generator experience.

B&W reactors have had some very minor tube problems.

The only tube pro};:>lem -- the only leakage*they have ever had has.

been at the Oconee units.

They basically have been free of --

COMMISSIONER BRADFORD :

Well '. none of the notes seem to

• correlate to anything in t..'i.e

~R. E!S~!HUT: !t appears to

• be a ci==:t=*..rer, and those should have been deleted, I believe.

COMMISSIONER BRADFORD:

Or else they may be just sort of separate comments.

MR. EISENHUT:

Separate comments, I beiieve.

.I have the one we published.which.only has three notes, so there's clearly a problem here, and mine is a: 12/2°9 update.

Let me explain.the B&W situation

• B&W steam generators have** only really found any problems basically in t.."'le Oconee units~

The only problems they have ha.d hav~ been high-cycle fatigue

. vibration. problems. *They have not seen arty wastage, t..1-iey c:flci* ~edeza/ cRepo-cte1r4,.!Inc.

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In fact, visually going out and looking with fibre optics it appears the tubes are*in fact very clean, there doesn't appear to be a lot of sludge buildup.

• It's a completely different flow characteristic.

What they do have, however, is on the very top of the steam generator where the flow goes up and rolls over and out, they have seen some what appears to be high-cycle.*

fatigue which has caused circumferential cracking.

It appears that the po.int of origin, or what's really caused it, has been -- it's not completely under-stood -- it appears to be driven by high cycle fatigue with just a basic vibration.

However, I should note that tb.e number of tubes that have been removed from service in all the three Oconee units is probably under 20. It's under 20, and the number that had any leakage is probably ~der 10.

They removed some because they thought there may be some problem there and they saw some degradation or some cracking and they plugged the tubes.

_aut on B&W reactors the steam generator tubes have been basically free of problems.

They do use a support plate configuration that's

.. different, and therefore you do get flo~ around between -- *

.there's no tube holes.and flow.holes, there's just one hole*

with a tube sitting in it, and the flow. goes betwee_n the

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But basically they've been free of problems.

24 There's been some very minor -- another very minor problem found when they go in and look they_ find what they call ndings" in tubes. It appeared that-someone rapped it with a hammer, perhaps.

They don't really think someone did, but thatS what it looks like, a small ding mark, like if you hit it with a ball peen hammer.

They don't know literally what_ they came from.

They may have been fabrication oriented,_or they may not-be.

COMMISSIONER KENNEDY; What other explanation might be MR. EISENHUT:

It's completely unknown at this ti.,ne. -The *E~N =~actors ha*,e had very littl~ adverse _

experience.

COMMISSIONER AHEARNE:

Darrell, could yo_u take just a couple of minutes and tell me what the chemical I

reaction of wastage is?

I MR. EISENHUT:

The chemical reaction of-wastage?

I just looked at that yesterday, or last night.

It's a situation where sodium phosphate originall~

had been used, and sodium phosphate, if the ratio exceeds 2.6, as it turns out, you have a situation where you have some,insoluble metallic phosphates that are formed by the reaction to the sodium phosphate with dissolved solids that -

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are in the feedwater system on the secondary side.

The reaction products of the impurities and of the corrosion products from the sodium phosphates tend to accumulate as sludge on the tube sheets.

25 COMMISSIONER AHEARNE:

Now, the reaction of the product of sodium phosphate with the tubes, or with the support plates?

MR. EISENHUT:

No, with the support plates.

And what they do is they cause a *substance commonly referred to as sludge, which builds up on the lower*: support plates.

The sludge pile, as it's called, on the support plate, which we've seen on some reactors, may be anywhere up to several inches deep, 6, 8, 10 inches deep in the center.

There are crevices between the tubes and tube support sheets -- for example, there 1 s a lot right at the tube sheet, where the tubes are not a complet*e1y rolled-in tube, they may be welded and rolled so that between the tube and the tube sheet there are crevices.

In*those crevices and in the sludge pile in the center region of.. the bundle where you' re getting a very low water flow or a restricted water flow,*l:;)ecause of the actual flushing phenomenon in the steam generator, you have a high-heat region, because of the circulation of the water.

The soluble sodium phosphates become concentrated by evaporative processes and are precipitated.-

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9 10 11 12 13 26 The phosphate precipitation causes localized

_wastage~

Now, it appears that they.corrected the cracking and the wastage problems in tubes --there was also stress corrosion cracking -- by* changing the sodium~to-phosphate.

ratio to below 2. 6, somewhat bel.ow 2. 6..

COMMISSIONER AHEAR.~E:

Where did the cracking come from?

You're describing sludge buildup.

MR. EISENHUT:

The sludge buildup sludge pile is where you get wastage.

COMMISSIONER AHEARNE:

Right, but --

MR. EISENHUT:

You can also get --

in the

. COMMISSIONER AHEARNE:. And the wastage was from 1~ I.*. sci 1:he er aCi<i.'lg that you' r~ j:;::!king al,out is c::acking Of 15 16' 1

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• the plates?

MR *. EISENHUT:

• No, the _cracking of the tubes.

There's been some cracking of the tubes due to the free caustic which is formed.from the sodium phosphate.

This is stress corrosion cracking.

• You can actually.* get~_;as it turns out, we've also seen another phenomenon where you can get actually cracking, stress corrosion cracking *from inside of the tube ~-,that is, the primary side. of the tube, in very clear water.. There is some phenomenon where you can see minor.* cracking *.

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.I 24 I I 25 27 If you look*up here, you can see that half a dozen plants, Westinghouse plants, have found h;storically stress corrosion cracking.

COMMISSIONER AHEARNE:

Then the way you solve this wastage problem is to reduce the sodium-phosphate ratio?

MR. EISENHUT:

The sodium-to-phosphate ratio,.

to below 2.6.

But-as it turns out, to. eliminate the wastage problem entirely, what they've attempted to*d~ is switch from the sodium phosphate treatment to a different chemical treatment.

COMMISSIONER AHEAR..~E:

And the sodium phosphate

.. ~nd * \\4'hy --

MR. EISENHUT:

To. eliminate the b~ildup of scale onthe secondary side of the steam *generator. Just

• try to keep* the steam generators clean, basically.

COMMISSIONER AHEARi.'TE:

Thank you.

MR. EISENHUT :*

I'm not a chemist,. so if you need a more detailed discussion we can certainly provide it.

CHAIRMAN HENDRIE:

Phosphate water treatment in boil~r water systems is a long-standing c.onvention of the steam plant business~.In these cases because of t.1"le sludge buildups*and in some crevices you get local chemical conditions which are not characteri$tic of t.11.e bulk stream..

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.25 of the secondary water, where the ratios.* and the PH and everything are what you expect them.to be.

And then. in the sludge pile and the crevices you get out-of-spec chemical conditions which led to wastage and some traces of stress corrosion cracking.

28

• In part I guess it's a combination of the physical design of the steam generator in conjunction with a water treatment.system which has, by and large, operated successfully on somewhat different geometries in other systems.

MR. EISENHUT:

Yes.. Basically, as you said, if, one way or the other ~ if

• it.* got high or

• low ;._ high, you'd get cracking; if it gets low, you can get wastage.

A..--id the approach was to go. to somet.""ling that volatilizes and escapes with the steam so you don't have the residual.

sodium phosphates left over that cause you problems..

On some long-te.rm efforts~- just to sort of close out this. part of ;t --there's been a considerable amount of effort underway for the last.few years in the industry ~o, in the labs, reproduce denting and to under-stand it. It turns out that an owners group of. a.lot of the PWRs have a major. program,:* run.and directed by EPRI, at a various number of places around 1;he country.

They're basically.aiming.towards -- because of time -- ~n new plants, looking at a new design, where cflce* ~ede-ra/ cRepo-rte-r~. ifnc.

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II I I 29 feasible they're putting in a newer design~. And the newer design, I mentioned a couple of things about it. It's a matter of flow distribution in the steam generator. It puts iri *stainless steel support plates, it puts in -- on Westinghouse it puts in -- I can't.think of the magic word they call it it's basically a support plate that has a --

if you can picture sort-of a clover-leaf design, with a tube in the middle, so the flow goes around the tube and flushes the area out.

So there's a number* of tb.ings that are being put into the steam generators to try to improve the design.

In parallel, there is some work~going on by DOE**,.

and by the industry, by a couple of.the chemical companies, that is considering chemical cleaning of steam generator~

to try to see if they can't go in and dissolve away the Fe3o4, to clean up the steam generators basically.

Oh, the word is "quatrefoil."

The other piece of t.liis actfon plan, so to speak, is the repair and replacement program~

Some of the steam generators have. degraded to -the point.where it's believed that --

COMMISSIONER AHEARNE:

Before *you go to.that, could you also summarize the current understanding of the chemistry that leads to this, what properties are in the c:f!.ctt-r'J-ede1ra/ cRepo-cteT4, ilnc.

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22 23 24 25 water, and MR. EISENHUT:

To the denting phenomenon?

COMMISSIONER AHEARNE:. Yes.

30 MR. EISENHUT:

It '.s basically an acid-chloride-sal t solution is formed in the crevice.

COMMISSIONER AHEARNE:

Where do they -- what are-MR. EISENHUT:

The chlorides can come from the secondary side of. the system.

COMMISSIONER AHEARNE:.

To prevent it would you have to have essentially a chloride--free water?

MR. EISENHUT:

It appears that certainly an essentially chloride--free water would do.it.

However, it may be physically impossible to get that free, because COMMISSIONER AHEA?.~lE:

Yes, but ! 'm to anderstand. --

MR. EISENHUT:

No, no, I understand.

To give you an idea -- and now I'm recollecting.:from a.couple of

. I years ago -- weive been tracking the experiance throughout J

the world on steam generator experience on these kinds. of

• steam generators, and. I can recall visiting a foreign* -

• country where.they pointed out that over the life of the steam generator they had had on the order of a few ppm c:P,lorides at the. maximum point in time, *and that* was only there for hours.

Generally they were down iri the ppb range, 50 to 100 ppb was the average chlorides, and --

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Were they getting denting?

MR. EISENHUT:

And they were still getting denting.

And that's the only real data point to that low a level which would tell you that you really don't need chlorides so much as they may just be a catalyst.

COMMISSIONER AHEARNE:

Yes.

Now, you're forming MR. EISENHUT:

That's right.

COMMISSIONER AHEARNE:* So the role of the chloride has to be as a catalyst.

MR. EISENHUT:

It's a catalyst, that's right.

COMMISSIONER AHEARNE:*.Are you sure that it's the chloride 'that is the only catalyst_? -

MR. EISENHUT:

No, we're.not. That's why there's an extensive program underway.

It appears that the industry has been trying to run tests in labs toreproduct it. Basically, it's been tied to some form of chloride, where they can really

_ reproduce denting. It does not have to Qe sodium chloride, it can be magnesium chloride, or COMMISSIONER AHEA.R..'lE:

Well, it '-s not *so much -re-

• producing the-denting that's at issue, is it?

MR. EISENHUT:

Right. It's COMMISSIONER AHEARNE:

Now, is the corrosion only found.between the plate and the tube?

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. 25 32 MR. EISENHUT:

Yes, in the crevice.

We have a high-heat region and you.also have an acid-chloride-salt.

So it's an extremely complicated chemical process that a number of the national labs are working on for us to try to understand.

There's been-a *number of studies.

As of this-point it's not completely understood.

That's basically why the new de_sign has been to design away from it rather. than to try to cure the problem by treating it with ario~her chemistry.

The

• chemical companies -- Dow Chemica*l. has a big program* to try to un_derstand it and to try to come up

• With something that -- in theory, if you can understand it you can propose a cure for it, or you can propose a preventiva medicine, or recovery ~edicine.

COMMISSIONER AHEARNE.:

How about the steel companies? _

MR. EISENHUT: *The steel companies are also*

• working.oµ it considerably, not.just in the United States but *. throughout the world *.

This is a problem that has shown up now in a*

number of foreign. countries; in the major nuc:-lear.community countries.

So it's a problem that~-

COMMISSIONER AHEARNE:

You don't find the same buildup in the conditions that __ lead to an accelerated buildup in the crevices,

• you don't find that same type of*

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10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 corrosion.occurring on the tops or. the bottoms of the plates?

MR. EISENHUT:

No, you do not.

33 And you also -- I should say, just to give you a feel for how complicated it really is, first we thought it was just the tertiary source of water, whether it was salt water or -- high concentrations.

We found that you can find it all the way down to the ppb range of chloride.

You can firid it --

COMMISSIONER AHEARNE:

Yes, but when you're stressing that it sounds like you're rather positive that it's the chloride that --

.MR. EISENHUT:

Everything we have seen would indicate that's what it is, because people have tried to use other things.

And we believe that that's what it is.

It certainly acts as a catalyst.

We don't want to conclude that in fact that's the only thing, and perhaps*! shouldn't be leaving that impression.

It's not a phenomenon that is very wel.1..under-stood at this time.

COMMISSIONER.BRADFORD:

What is this meaning for the Staff position in CPs and OLs?* Are we requiring measures with this in mind?.

MR. EISENHUT:

Basically, yes.

We're requiring a number of things.

We're requiring a very th9rough die~- ~ede,ra{ cRepo-rt~j, !lnc.

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.16 17 18 19 20 21 22 23 24 25 34 inspection program, we're requiring -- on the ones that are already built.

COMMISSIONER BRADFORD:

Right.

But what about the ones that are --

MR. EISENHUT:

The ones that are not built, basically the plants that have steam generators that are still in the shop and can be modified, are being modified.

For example, to put in new support plates, to change flow distribution.

• 1 COMMISSIONER BRADFORD:

Are we requiring that?.

MR. EISENHUT:

Yes, we are.

We have a license condition that we're actually putting in all the new licenses saying that they should actually put in the secondary water monitoring program to try to inhibit steam generator tube degradation.

And we say there are several things that need to*be put into this, basically looking at following, monitoring, the seconc:?:ary chemistry and monitoring the product,. the steam generator behavior.

Now, I should say we put on secondaey*water tech specs on a.number of plants.

However, in all honesty, at the same time, putting on secondary water tech specs doesn't necessarily solve the problem, because if you have a condenser tube failure you can't say thou shalt not have condenser tube failure.

If it happens, it happens.*

So the important thing, really, is to monitor c/1-ce-r:f ede1:a/ cRepo1:ta~, !Inc.

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10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 35 very*carefully what's there to try to understand it better on those plants that are going to go into operation.

On those that are not yet fabricated and can be fixed in the shop, to.try.to fix them up.

COMMISSIONER KENNEDY:

What does fixing them up entail?

MR. EISENHUT:

Well, fixing them up means if you can put in different support plates, put in different -

support. plates.

That. is, change.the design.

If you can change the material, change*the.

material.

If.you can change the flow pattern, change the flow pattern.

Those are the kinds of things that are beinq looked at.

COMMISSIONER BRADFORD:

Are there possible requirements -- and maybe you were about to get to this anway -- that ought to be imposed that would make it easier to repair or replace tubes in the event that we haven't go_t the problem solved, if that continues? _

MR. EISENHUT:

That's one of ~he things we're looking at under:-- we have three task action plans that we're-working on, one for each of the major vendors.

• one of the considerations there is should *plants be designed for the change out of steam generators?

Should.

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• 16 17 18 19 20 21 22 23 24 25 36 they be.designed for the change out of tube bundles?

My personal view is that we should be looking very hard in that area.

The industry, more than we, should be looking hard in that direction.

I suggested it, in fact.

In September the NRC sponsored a workshop where we.had about 100 people from all the industry represented.from around the world.

That was certainly a suggestion I know I made to them.

I think -- in looking at some of the foreign plants, for example, even some of the older European plants, you can find that the plants there are designed for change out of steam generators.

• I can remember one plant that right on the deck where the steam generator would be lifted up the?:e are actually already today existing railroad tracks in the deck so that. you can put a dolly*

there, lay the steam generator on it, and there is a hatch in the wall big enough to take it out,*right straight out through the wall of. the containment.

COMMISSIONER BRADFORD:

I assume that :ras a fairly significant potential for reducing worker exposures in MR. EISENHUT:

It should very much, because --

• COMMISSIONER BRADFORD:

in the.event that you: do have to MR. EISENHUT:

It should, because you don't cflc~- Crede-ral cRepo-rte-r~, !lnr:.

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I 37 have to do a whole bunch of modifications such as taking out walls, et cetera.

They designed-* it with -that in mind.

But it gets back to, you know, a different.

philosophy that people have had.

Here, the attempt has been to design the steam generators to last for 40 years.

And I think the industry is looking very hard at that requirement right now, or that outgrowth.

COMMISSIONER AHEARNE:

Is the primary health and safety concern the worker exposure in repa~r, qr MR. EISENHUT:

• I'll get to that in just a moment.

That's basically it, yes.

COMMISSIONER KEN?tEDY:

Would you get to t."1.e.

description of the rate at which this is occurring?

You s_aid earlier that perhaps* steam.generators had a 30 percent redundancy in tubes, and we're talking a.bout 26 percent plugged already in Surry.

MR.. EISENHUT:

My next-slide just happens to have that.

Could I --

• COMMISSIONER KENNEDY:. Not knowing your nex.t slide, I'm delighted.

please?

MR. EISENHUT:

Could I have the next slide, (Slide.)

I've got the next three slides t.."lat will help*

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.38 you out.

This is a picture of -- actually it's as of June 78, so the inspect~ons this year, over the last year almost, a.re not quite there.

It-doesn't really change things that much.

You see, if we look at Surry, it '.s about 21 percent.

Surry-2 underwent art inspection this year_ and went from about 21 percent to 24-1/2.

The basic approach ha~ been it's been-increasing*at the general rate of about 3 percent plugging per inspection~- or is it per year?

Yes, 3 percent per year.

We'll get to it in just a moment.when it shows up again.

COMMISSIONER KENNEDY:

And*the inspections are about twice a year?

MR. EISENHUT:

Normally, on the Surry plants and the Turkey plants we've been requiring somewhat less, 6 to 9 months.

COMMISSIONER KENNEDY:

I thought you said it was 6 months earlier.

MR. EISENHUT:

It's about 6 months.

It varies somewhat, and on the next two slides you'll see that.

The percent plugged in the other plants you can see is. basically insignificant, with* the exception of Palisades, wl'lich hasbeen basically a wastage proble.'11~

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10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 39 Palisades plant was a plant that~ - most of.its tubes that are plugged were plugged because of wastage problems, and it has not significantly changed in the last year or so.

COMMISSIONER A.HEARNE:

Do I gather that some of the plugs come out and some of the plugs don't hold?

MR. EISENHUT:

Yes.

There's a whole bunch of corrolary pieces --that's one -- that have come up.

We have seen some cases where plug~ have either apparently not been put in and fired -- these are the explosively fired plugs, or where they have begun to leak, or where they have actually --*I guess those are _the only two.

reasons.

One would be where -- well, there's a third, h

-it 1

d were_ was w1s-p ugge.

There were three things that we've seen in actually the QA of the inspection:

One is some leak, some fall out from apparently not being exploded, and, third, sometimes they put it in the wrong hole.

That is, they plug the wrong tubes.

We *have met with those plants that have had

• tnose problems, and we've met with those that have been doing extensive-plugging, and*we put an extra QA check on them quite thoroughly.

We've asked_ them to tak~ pictures before,.* and J;>ictures after.

• We've asked them.to go through. am audit those pictures,. actual photographs of*.the.

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10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 40 bottom of the tube sheet, so you can see where the plugs are.

We've actually had them brought to us so that we can look *at them on occasion too, and we've had I&E follow up and run checks on the act~al plugging.

COMMISSIONER AHEARNE:

Well, when they're leaking what do you do?

Do you try to re-plug it, or MR. EISENHUT:

If. it's basically a leaking plug, yes, you have to go i-n and ref ire. it or try -tQ ~-eal -the plug.

And in every case they have.

Most of the occasions it's been that they had riot been fired.

COMMISSIONER AHEARNE:

So where in Surry 1 arid 2 you have leaking, does that mean that that's continuing to leak, or they were-leaki:1g and they've fixed them?

MR. E:SENHUT:

They wera leaking and they've fixed them.

In general, any time a* tube is leaking, by any means,_ whether wastage or crack, denting crack, plug leak, when the plant is down those are fi:ted.

An~ in fact it's fixed in that general area.

We're-using a cannon to kill a mouse, basically, is what some people are complaining, by the plugging pattern~

If you see a problem, plug a couple do_zen tubes around it.

(Slide.)

The next slide starts getting us to basically the Surry-1 and Surey-2 situation. This will give you a d/,ce- ::ledtta! c.Repo1rte*u, !lnc.

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11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 little better feeling for the number of times that we've seen Surry-1 and Surry-2 be up and down.

You'll notice back in the 75-76 time period there were a considerable number of leaks, most of them small, up to that point in time.

41 Late 1976 was when there was some extensive shutdown with extensive inspection, and you will notice that the number of tubes that were plugged in late 1976 dramatic-ally increased over those before: It went up to 804 tubes.

This is because of the conservative plugging pattern, and you'll see that that has continued, basically.

The 804 was basically the baselL,e, -when anything that was in any doubt was plugged.

The nu...~bsr of tubes, you can see, continued ~.,it~

1

-1 inspections up until March, when they were shut down because of the seismic order.

They in fact then did some inspections and al:so plugged a few more tubes.

COMMISSIONER AHEARNE:

Then you'd say 30 percent is roughly the cutoff point?

MR *. EISENHUT:

It would be in that ballpark.

However, you*could begin at that point to start derating the plant. It doesn't mean it's -- it's not an immediate thing.

I should point out also that generally the ECCS evaluations do not include the base case that I c::llce- 'Jede'laf cRepcnte'l~,.!lnc.

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include, evaluations with tubes plugged,.initially on a plant.

42 So,* as it has proceeded we've redone ECCS evaluations with plugged tubes, because the amount of flow through this primary circuit is changing every time.

The effect on**tne steam line breaks with less heat transfer is changing.

There are changes that are being incorporated.

We're up now I think to where they're authorized for 25 percent plugged. It gets more complicated if you get up to a point where you have to begin to derate.

. COMMISSIONER AHEARNE:

You say they I ~e authorized for 25 percent plugged.

Now, what.does that mean?

MR. EISENHUT:

That means they have an approved ECCS evaluation model.that includes up to 25 percent plugged tubes.

COMMISSIONER AHEARNE:

So when they plug another 40 tubes MR. EISENHUT:

If they were. shut down for.

another major plugging they would have to be in.for another ECCS approval.

That's basically -- they've gone through this process three or four times.

COMMISSIONER AHEARNE:

I see.

• MR. EISENHUT:

This means more. evaluation.

COMMISSIONER AHEARNE:

Do.you have any -- there's dtce- ":Jede'!a! cRepO'lter:1, !lnc.

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~ow many tubes you can plug before you have to derate, or --

MR. EISENHUT:

Generally in the ball park we've been talking is around 30 percent.

That's a very rough number.

That's the kind of thing we're looking at to address, to maintain appropriate margin.

We're talking something in the order of 30 percent.

We projected that 30 percent, incidentally, about two years ago, and it ' s still a

• number we 're looking *.

at.

MS. MOE:

Darrell,. wasn't there just a matter of an increase to 28 percent?

MR. EISENHUT:

There could.well have.been.

I've 13 1-been tied up a little bit. It was 25 percent the last time i4 15 16 17 I 1a I 19 20 21 22 23 24 25 I looked.

Jos's scratching his he~d, too, so percent.

MR. SCINTO:

I think there's.one in the house.

MR. EISENHUT:

There may be a' request for 28 MR. GRIMES:

It's not out yet.

MR. EISENHUT :. Okay. - Generally 9n

• these both Joe Scinto and myself get involved when we.go past higher and higher levels.

In fact, I guess I should say an inte+nal QA approach to this is~ Joe's general ap~roach in ELD has been that he will not let.the approval go by until I've looked at it, because we.want to be sure that

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10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 44 gets to higher and higher levels, because at some point and I don't know what it is today -- but at some point you would probably have to sit back and reflect and say that enough is enough, and you don't want the plant to operate in that mode because you may have stolen a lot of margin.

So that's why we've been following it ~ery closely.

(Slide.)

The next slide is the*same thing for surry-2.

You can see the same kind of a general approach *. This is a little out of date, because there was early this year this plant was shut down, well, it's been shut down.

So

• COMMISSI*ONER AHEARNE:

Was the main reason for replacement of the steam generator the plugging?

MR. EISENHUT:

Yes.

COMMISSIONER AHEARNE:

But they went as far up as Surry**--

MR~ EISENHUT:* Well, you have to look at this in time, because initially they were.. And this is the plant that had. the leak of the 80 gallons per minute b.ack in Septe.inber 1976, and at* that point in time they were having a greater amount of problems.

It was a matter of which plant *ao you embark upon first, and certainly j;.f you shut do~ Surry-2, Surry-1

• is going to outrun it in the number of tubes plugged, dl-ce-r:l-ede-ra! cRepo-rte-r~. !lnc.

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j 14 ii 15 j 16 17 18 45 because with every two months that goes by, there's another shutdown to plug more tubes.

COMMISSIONER AHEARNE:

Yes.

My only point was that I saw in your previous chart that Surry-2 is now at 24.6 and MR. EISENHUT:

Is now, th_at 's right.

COMMISSIONER BRADFORD:

Darrell, what you were saying was that when a decision had to be made on the --

what, additional tubes ordered, or the steam generator itself ordered, they were roughly at --

MR. EISENHUT:

When the basic decision was made it's looking at a number of things, and the basic* decision that the utility made was it proposed removing -- replacing Surry-2 first.

COMMISSIONER BRADFORD:

What is the lead time involved in that?

When did they have to make that decision?

MR. E!SENHUT:

I th~nk they ordered the.'?1 back in 1977.

They have ordered steam generator bundles for_

1s*

both surry-l and Surry-2. They're three-loop plants, so 20 21 22 23 24 25 they have 6 replacement-lower bundles on site right.now, today.

COMMJ:SSIONER AHEA.R.."'IE:

So. that. they intend to also.replace the plugged MR. EISENHUT:

Eventually they will replace them in the other Surry unit.

They do have a plan for that.

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• 10 I 11 I 12 13 14 15 16 you look at --

COMMISSIONER KENNEDY:

replace all of them?

46 Is it necessary to.

MR. EISENHUT:

They will replace them all, yes.

If you look back historically, they've been running pretty much the same amount of plugging.

There wasn't any significant difference.

I think the bumping from 21 to 24, or 20.5 to 24 percent, was actually earlier.this year.

And at that time Surry-2 was already down, in the program. to be removing steam generators which started in December.

We gave Surry-2 approval of the safety evaluation December 15, and.. we issued an environmental impact appraisal in early Januar'?.

COMMISSIONER BRADFORD:

The new tubes will have the different holes and other things you were talking 11 J

. about?

ii ii 18 }

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MR. EISENHUT:

Yes. I'll get to the package on the new *tubes in just one moment.

CHAIRMAN *HENDRIE:

I think maybe we*' d better try to* move forward with the briefing.

We 've got another

• subject yet this morning.

MR. EISENHUT:

Surry made the decision to replace their steam generators~

In about mid-1977 they

• ordered them.

They chose the* replace.?Jtent option~* ** They had c4ce- ~ede-ra/ cRepcnte<r4, ifnc.

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to make that decision on the lead time, even though they recognized that at *that time we were beginning to have*

discussions about another option that may some day become available*.

That is, the retubing in place, where you cut 47

• 5 the steam generator in half, go in and remove the tubes, s I I

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9 10 11 12 16 11 I

,a !I 19 20 21 22 23 24 25 cut them out section by* section,

• drill them out of the tube sheet, and put in new tubes.

That option I won '"t d_well upon, except to say tha:t we've been having discussions with Westinghouse, who have been proposing it somewhat over the last couple of years.

Early this last year we told them, in May of 78 we told them we had some questions about it yet.

We presently are reviewing that effort on some"'.i.that of 3. low-key effort~

We' re going to be s~nding some qUestions orit to them shortly. It may be early next year before it's approved on any one plant.

MR. GRIMES:

I think we received a topical report.

on that in January of this year, on the retubing.

COMMISSIONER BRADFORD:

How much does it cost to replace three steam generat~r tubing?

MR. EISENHUT: I'll be summarizing that in just a second.

COMMISSIONER KENNEDY:

Are you going to tell us how they're actually going about it physically?

MR. EISENHUT:

Yes, I'll try to run through it*

I.

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briefly to show how it's being done.

Basically, they made this decision because the steam generators were on the road to being either derated or raising real serious safety questions.

They chose the replacement option, because it was the one available at the time.

48 They estimated that if they planned everything out very well in advance it would be a six-month or better effort.

The new steam generators had improvements in it which would have a full depth expansion of the support plates, there would be no crevice~

The support* plates were changed from carbon steel to stainless steel of the qu.at=afoil It has i~spec~ion ports i:i t:1~ steam generator.

Those kinds*of things.

approved.

It actually tried to treat the problem ~Y design.

The removal and replacement approach was*

The safety evaluation, as I said, went out

• December 15.

The EIA went out January 20.

There was a safety* evaluation and.an environmental appraisal for both units.

The utility began to work on the Surry-2 plant as soon as, in fact, our approval went. out.

They actually had a several hundred men crew sitting at the site waiting on the evaluation.

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I 19 20 21 22 23 24 25 (Slide.)

The next slide gives you a quick view of what they're going to do.

This is just a cross-section of the steam generator.

49 Basically,they're going to be cutting it in half, right about the u tube region, and removing that lower section,that is, with the U tubes in it.

(Slide.)

The next slide removes the internals and shows just a crosscut of what they're going to be doing.

They will be cutting out the main** steam pipe on the top, then they'll be removing the top head, with the steam separators, dryers, et cetera, and setting them aside in the plant.

They will then be cutting the.,blower assembly out at the transition cone area.

They will be removing piping at the bottom.

And you can see the locations of cut *.

They then will have a piece which will look something like the next slide.

(Slide.) -

the This is the piece that they will have.

They will basically be removing this piece in its entirety, and bringing in a new piece.

The next slide shows you just somewhat graphically c:f!.ce* '7edera! c:Repo1:te1:J, !Inc.

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.25 what they're going to do.

(Slide.)

50 They're going to pick it up, pivot it around, lay it on the dolly, and move it out the existing equipment hatch. It clears by a couple of inches.

There's not a lot of room.

If, in fact, they had to -- if they couldn't fit it through, then there would have been, of course, a bigger push to go for some other options, I believe, because it would entail cutting through the contain.~ent.

I guess I should point out at this time that eveh though we're concentrating on Surry today, Turkey Point 3 and 4 are presently being reviewed by the Staff we have not sent out the approvals -- we are still reviewing those.

They've requested approval to go to the replacement option.

They are the prime mover, actually, to t.ry to get the tubing option reviewed as soon as possible with Westinghouse.

However, it will be some time before it's going to be approved -- if it's approved.

It just takes time to do these things.

There's one other plant, ncUitely Palisades, which, because of their large* amount of wasted tubes t_ha t haven't been plugged, is considering steam generator replacement.

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!,I 51 also. It's not being reviewed on a high priority at this time.

I believe their option would entail cutting a hole in the containment to remove the steam generators, because they don't have the luxury of being able to take them out through the equipment hatch.

T.his is basically very simply the approach that's going to be used.

MS. MOE:

Darrell,-could you describe whether this will raise an exposure problem, that cutting --

MR. EISENHUT:

Sure. It's simply going to come from when you cut the -- the inside of the system contains radioactivity due to this primary coolant water.

So the

• minute you* start cutting steel which has radioactivity on the insi.::.e, you get one source

!t can be a..'"'l airborne product.

You can also have some direct radiation from what's deposited on the inside of the surface from workers working on the outside.

Those are basically the two sources of the.immediate radiation.

Brian, what are the other MR. GRIMES:

I think we can through in a minute

• and say.what the experience is, where we are.

MR. EISENHUT:

Yes, we'll summarize actually how far they are on this process today, the amount of radiation they've gotten, where it came from, and what the c:fl.ce- :3edetta! cRep0-rtett1, !lnc.

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25 52 number is, and how it's comparing to their projection.

Basically all I'll say on the repair approach is they will be cleaning the thing up, hydrostatic testing, I

and eventually, of course, they'll do a baseline in-service I inspection. They'll do a: considerable amount of pre-opera-I II I

tional testin~ of the instruments, components and systems.

They'll go through startup tests, and they'll do* some thermal hydraulic tests.

The steam generators from a thermal hydraulic*

standpoint are essentially identical to the ones that were there before. That's what made the safety evaluation and review qui~e straightforward.

The staff also did an environmental impact appraisal, and the next slide (Slide.)

I'm sorry, there's one more slide.

The steam generators,when they're removed, will be housed in a building on the outside.

There is a roof on this facility; it doesn't show it here.

They are housed outside.

. COMMISSIONER AHEARNE:

What Is. that.building?.

MR. EISENHUT:

It's a concrete building*that wa:s designed at the plant COMMISSIONER KENNEDY.:

Especially for this purpose?

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53 MR. EISENHUT:

Especially for this. purpose.

COMMISSIONER AHEAR.."IE:

• So there are some standards of radiation exposure on the o.utside?

MR. EISENHUT:

Yes.

COMMISSIONER AHEARNE:

Is it a sealed building?

Does air flow through, filters on it, air filters?

MR. GRIMES:

There's a particulate filter, yes.

MR. EISENHUT:

The steam generators themselves are sealed.

There's the top pins, and the holes are sealed.

So it's a sealed system.

COMMISSIONER AHEARNE:

You mean after it's cut it's sealed?

MR. EISENHUT:

After it's cut, it's sealed.

(Slide.)

The next slide -- we'll try to summarize now where we are with the occupational radiation-exposure.

We issued an environmental impact appraisal, as

!I 1a

. I said, in January.

19 20 21 22 23 24 25 Basically -- let's start at the-bottom.

At the time we did it, the 1977 average for manrem exposure at a plant in the U.S. was about-~

COMMISSIONER KENNEDY: You said a plant?

. MR. EISENHUT:. At a single-unit plant.

COMMISSIONER BRADFORD:

Is the Surry steam generator replacement for just Surry-2, or is that.both?

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5 MR. EISENHUT:

Both units.

And I'll -- I'm sorry, the number there is per unit. It's 4140.

The numbers were a little confused, because the proposal was for both units. I'll try to keep them separated as we go through this.

54 6

7 8

The 570 is for a single-unit plant.

The range in 1977 was from 87 *to 3100 manrem.

I believe the 3100 was at Pilgrim, a problem with inspections of a vessel.

9

. 10 11 That's generally the klnd of numbers that we've seen at-plants. That's also the range that you see *at inspections of the plants.. And there.' s a* number of them, 12 I* because of different inspection things that get you there.

13 j VEPCO 's estimate wa:s about 2070 manrem for the

.. ;I

-14 !I total removal operation of the three stea'!l generators at 15 i one plant, 4140 for two.

16 j The NRC's estimate was 3380 to *s.liOO per unit:.

17 1 That was our initial estimate.

I 18 I COMMISSIONER BRADFORD:. Does the 2070 correlate 19 to something -close to the 5840, or to *3380?

• 20 MR. EISENHUT:

• I' 11 go through that in just a 21 second.

22 The. first number was we estimated it would be 23 *

• between 33 and 58 hundred.

24 25 COMMISSIONER GILIN.SKY:

Now you can It really es~imate these things with three figures, can you?

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MR. EISENHUT: --Brian, do you want to address that one?

(Laughter.)

MR. GRIMES:

What they've done is gone through each step and added up a.number of small components to a *1arger one, and carried the numbers.

But you're right, it's probably 55 MR. EISENHUT;:

We_ had a study done at Pacific N9rthwest Labs that went through*item by item of the major aspects of the removal process,- including preparation, the removal, the cutting, the cutting of various pipes, lifting off the steam drum, the dome, the reinstallation, the reinstalling of primary.system piping.

They went through* item by i tern, and -they calculated -between about-_

3300 and 5800.

MR. GRIMES:

I might point out that that was 17 done on a generic basis, independent of the specifics: of ii

• 11 1a,

the Surry station.

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25 MR. EISENHUT:

Yes.

MR. GRIME_S:

And it did *not.take into account

~he specific dose rates at Surry, or* the loc_al decontamina-.

tion measures that Surry later proposed.

_MR. EISENHUT:

That's the kind of thing we'll be getting to.

As Brian has mentioned, this is a generic study we had done first, because we recognized we would be c4c~- 'Jede'la/ cRep;1:te1:~. £Inc.

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addressing it on Surry and Turkey. *And PNL looked at it and got information from VEPCO and* Florida Power & Light, arid did the study all at the same time.

56 The numbers would be dependent on, as Brian said, how* much decontamination we do, shielding you put in, and a number of things.

MR. GRL'!ES :

And I think we later agreed with the Licensee's estimate when we issued.the evaluation

• MR. EISENHUT:

Yes, that's right.

• COMMISSIONER GILINSKY:

How many individuals is that spread over?

MR. EISENHUT:

I think it's hundreds of people.

13 I CHAIRMAN HENDRIE:

• At least 400.

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. COMMISSIONER AHEAR...~E:

Would the calculation 1.5.

depend on the number of people?

16 17 18 19 20 21 22 23 24 25 MR. GRIMES.:

I think it is.

To some extent., the training varies.

MR~ EISENHOT:

Only through training, I believe.

MR. GRIMES:

In other words, if you have experienc d men they'd do it faster than --

COMMISISONER AHEARNE:

What I was really asking, though, is MR. GRIMES:

It's not very sensitive to that.

MR. EISENHOT:

I remember Srian pointed out an example before once, where if a guy is well trained he won*' t cllce* :Jede-raf d?.epo-rte-:1, !lnc.

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I 57 forget to take a wrench with h.L~, so that he has tog? back through the tents and go back into the decontamination ten~s, and --

COMMISSIONER AHEARNE:

What is the fundamental difference between you and VEPCO then?

MR. GRIMES:

Initially the PNL report came out with higher numbers, and the main differences were local decontamination planned: by* VEPCO was not taken into acr=ount **

The specific local radiation levels were not taken into account-:-they were over-estimated as it turns out, by PNL in their initial report that used local radiation levels of a couple hundred mr instead of tens of mr.

COMMISSIONER AHEARNE:

You're talking about the P~-1!. -study for ~RC?

MR. EISENHUT:

Yes.

MR. GRIMES:

Yes, the generic study done for us.

And I think there was some local s-hieldinq that also was not taken into account.

MR. EISENHUT:

Yes, I think tha_t the difference in the 33 and sai ~s I re~all, was.-- that was our estimate, our staff and PNL's estimate, including some shielding and some prudent measures.

If they_do more, the number goes down* further *.

For example, as I recall, VEPCO was going to go in with high-pressure water to try to clean off the surface

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19 20 21 22 23 24 25 58 and decontaminate.

They were doing some decontamination work.

If you decontaminate, the number goes even lower. 1 So if you put in a few other aspects, it goes lower.

We generally were in agreement with that number and our evaluation bought that.

COMMISSIONER AHEARi.'1E :

Which number?

MR. EISENHUT:

The 2070 per unit.

(Slide.)

The next slide Brian you'll have to help me with these two -- this is an exposure history.

To put things in perspective, this is -- for the last three years we've looked at the Surry Station -- I don't know whether thii is a unit or... it appears to be for t~e Station.

The total exposure at the station in '77 was 2400 and 3163 in '76.

You can see the fraction of that that WdS associated with steam generator inspections.

Because of the continuing problems with the steam generators, that inspection was continued if you did not replace the steam generators.

So this is on one side of the house.

This is the thing we're comparing against on the other side..

MR. GRIMES:

I have two other numbers, one for 1975, the totai' exposure was 1649.

And we just have the cltu- ~ede,za/ cRepo-cte'l~,.!Inc.

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25 1978 numbers now for two units, and that is 1837.

COMMISSIONER AHEARNE:

Total exposure?

MR. GRIMES:

Total exposure.

COMMISSIONER AHEARNE:

How about from steam generator inspection?

59 MR. GRIMES:

I don't have the number for '78.

I think there's *.*

MR. EISENHUT:

We'll have to check the number.

There were two inspections at Surry-2 and two inspections at Surry-1 in '78.

The ave.rage repair steam generator ISI's for other non-severely degraded plants could be on.the order of 25 to 100 manrem, to give you a rough ball park.

So what we're sayi.:1g is if yoU:*recall lcoking at the last slide, and looking here, you see a considerable amount of manrem exposure associated with.steam generator inspections.

The after repair would be back down to that level of 25 to 100 manrem.

COMMISSIONER AHEARNE:

Assuming that these fixes.

are --

MR. EISENHUT:

Well, assuming it goes li.kethe rest of the industry.* A*lot*of.the industry's non severely

• degraded steam generators are averaging* 25 to 100 manrem.

degraded~

COMMISSIONER AHEAR.."l'E:

Non "yet" severely dtce- ~ede'la/ cRepo-rteiJ., !lac.

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Yes, non "yet" severely degraded, extensive on the chart, that's right.

COMMISSIONER AHEARNE:

Yes.

MR. EISENHUT:

So you'd expect it to be a*large s I bump amqunt, and then decrease.

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If the solution is correct.

MR. EISENHUT:

.If the solution -- and we would certainly expect it to be for certainly a number of years, because even on those plants that"are not yet, there's been a number of them that have been operating for many, many years.

COMMISSIONER AHEAR..~E:

The 2070 is per unit?.

MR. EISENHUT:

That's right.

COMMISs:biER 'AHEARJ.iE:

The 2000* is your estimate for the requirement for the replacement of a single unit?

MR. EISENHUT :. That 's right.

(Slide.)

The next slide gives vou a rough breakdown of the pieces I just menti.oned a minute ago.

This is, again, comparing those two estimates.

These are just figures from the r*eport that we have -me~tioned,

• the generic report.

COMMISSIONER AHEARNE:

Now, I thought most of your -- is the big difference on the installation due to shielding that they are proposing?

MR. GRIMES:

Partly.due.to electropolishing of*

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II the sections*of pipe, they were able to reduce those, and it's partly due to local shielding.

CHAIR."!AN HENDRIE :

Forward, please *

(Slide.)

61 MR. EISENHUT:

The next slide changes the subject from the radiation aspects to cost aspects.

This is the replacement cost for the entire fa~ility, $133 million.

The *first line is about -- the

. replacement cost is -actually the buying of the hardwa*re and replacing it. It's about half and half.

They initially, I believe, were about $10 million per steam generator.

It's about $66 million new dollars.

COMMISSIONER AHEARNE:

This is for the station?

Ha.* E!SENHUT: * ':'his is for the station*.

The final disposal number is-~

COMMISSIONER AHEARNE:

"Final disposal?"

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! about?

MR. EISENHUT:

No, I think*that is the building.

This is act.ually

• putting it in the.building.

COMMISSIONER AHEARNE:

It s'tays. on the site?

MR.* GRIMES:

It stays on the site until decommissioning of the facility.

.MR. EISENHUT:

• The replacement power is the differential cost simply based on df.ce* ~ede'f:a/ cRepo'f:teu, $nr:.

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COMMISSIONER KENNEDY:

Over how long a period?

MR. EISENHUT:

The replacement power?

This is basically one year, six months on each unit.

Each unit is being projected to be down for a six-month period.

There-fore, six months on unit 2 and six*mortths on unit 1.

• . COMMISSIONER AHEARNE:

Is it planned that. as.

soon as the current units would be repaired then they'll*

take the.other unit down?

• MR. EISENHUT:

That's* the general approach.

They *-initially* hoped to bring unit 2 down in January and bring it_ bac.k. up about six months* later, _ to have it repaired and start doing testing.

After they would I

get unit 2 back on line they would.close unit 1*and do that.

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.Basically-,. thcsa ~=e _the ~ra:=-ious aspects of replacement.

Brian has.got t..'1e status basically as of right __

at this moment, where they are on this program, to make

~ome compar_isons.

MR. GRIMES:

Let's go back_ to slide*aB, and show exactly where they are *..

(Slide.)

Rig~t now; they've made-the cuts on the primary

_ system piping* an_d have remqved those sections of pipe.

They '.ve removed the main steam llne.

They 've cut the feedwater line.

They've cut the transition cone, and df.ce* 9ede-ial cRepO'Cteu, £Inc.

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• 22 23 24 25 removed the top piece of the steam generator with the internals and set it aside.

COMMISSIONER AHEARNE:

Is this for all three?

M~. GRIMES:

That's for all three steam generators in Surry Unit 2.

If I could have the supplemental backup slide, please, manrem.

(Slide.)

63 These manrem estimate5 are Surry manrem.estimatesi They're slightly*different numbers than you saw in the other slide because they're for work performed to date.

But the actual manrem, on the right-hand side, is compa:r_able to what.the estimates were for the work to date.

Remo~al.is only partially cc~pleted.

COMMISSIONERAHEARNE:

The removal figure that you have there is much less than the total removal *.

MR. GRIMES:

Yes.

They must now take out th~

steam generators.

MR. EISENHUT:

This is only indicative of looking at the subparts, how they' re proceeding today. *

• so the only conclusion.I would draw from this is basically*

their estimates are in the right ball park.

MR. GRIMES:

One other note of interest is that the main coolant.pipe has been electropolished, and the radiation levels inside the pipe has fallen from about 10 r dice* 'Jede-:al c:Repcnte1:~, !Inc.

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So their estimate on reduced doses during welding appear to be supported.

CHAIRMAN HENDRIE:

Onward.

MR. EISENHUT:

That's it.

COMMISSIONER AHEARNE:

Are any other plants planning* to go through the steam generator replacement?

MR.-EISENHUT:

Only Turkey Point-3 and 4 have got tentative plans.

No firm timetable.

COMMISSIONER AHEARNE: *Andis it still at discussion whether to go this route or the Westinghouse cut-open?

64

• • MR~ EISENHUT:

To a certain extent, except we' re reviewing the replacement* aspect right now.

!t dapends a lot on

• t!'la ti:ning.. They may well go to the retubing option if we would have it reviewed in time, but it would probably be another year before we'd get it done.-

MR. GRIMES:

I think they're looking at replace-ment.on unit 4; and a possible option of retubing on unit

3.

MR*~-sCINTO~

They have to"chop out a shielding wall.

MR. EISENHUT:

They have to*chop out a-piece of.

concrete to get down to the hatch, because it's basically at a* lower level.

But it's again tied to the timing.

If.

dice* ':Jede-ra/ c:Repo-rte<rj, !lnc.

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13 I 14 15 16 17 18 19 20 21 22 23 24 25 they go with unit 4 first, which they're talking about, because unit 4 has had forced degradation, they would probably want to go with the replace.~ent option on that, and the retubing option on the other.

COMMISS.IONER AHEARNE:

What's the highest percentage plugging that you had there?

MR. EISENHUT:

The last data I had was about almost 20 percent on unit 4, just under.

65 COMMISSIONER AHEARNE:

• And is that the worst of

.any other operating plant?

MR. EISENHUT:

Except for Palisades, which is a wastage steam generator.* Palisades has considered two things~

They tried to go in with a tube sleeving option, where the*tubes have basically been_thinned down, and they stick a little sleev.e on the inside.

And they have 30, 35, 40 -- something like that -- sleeves in place today. It's a test program.

COMMISSIONER KENNEDY:

On the inside?

MR. EISENHUT:

On the inside.

They basically slip them up and expand them out *.

COMMISSIONER KENNEDY:

Expand the pipe out?

MR. EISENHUT:

Yes.

COM.?.!ISSIONER KENNEDY:

So that, in fact,* the tube probably has a-resulting internal diameter greater than it now possesses?

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No, they only really expand them at the top and the bottom, so it's basically slightly smaller, but it's much stronger.

COMMISSIONER KENNEDY:

I see.

CHAIRMAN HENDRIE:

The flow area reduction for

• an.internal sleeve is not that significant.

You do lose a little, but it's not significant.

a II MR. EISENHUT: - That's right.

I 9-* I CHAIRMAL.'1 HENDRIE :

The main. thing is to strengthen!

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COMMISSIONER AHEARNE:

What percentage is Palisades -at?

worst :one.

MR. EISENHU:':

~6ut*22 percent.

COMMISSIONER AHEARNE:

So. actually Surry is the MR. EISENHUT:

Yes.

COMMISSIONER AHEARNE:

Thanks.

CHAIRMAN HENDRIE:

Other questions?

COMMISSIONER BRADFORD:

If you look out five years, or if you look out ten years, how many plants would you anticipate having to replace steam generators?

MR. EISENHUT:

That's so highly dependent upon whether they come up* with some better s_olution to, for

• example,chemically clean things.

I would not be surprised diet!- ryede'la! cRepo'ltl!'l~, ilnc.

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9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 67 however, to see steam generators on these older plants --

on replacement; I wouldn't be surprised to see that that's done on a number of plants.

I would be surprised to see it on the newer plants, because it appears that-they've designed.away from the crevice, so, therefore, you wouldn't see that. That's not to say that there may not be some other new phenomenon that comes up.

COMMISSIONER BRADFORD:"

Two of the oldest plants, Yanke~ Rowe and Zion, didn't appear to have the problem.

Do.-:-you know why not?

MR-. EISENHUT:*

No, you really cana!.t pin down why not.

There's a lot of olde~ plants that don't really ha..,e the prob.!.e.'!1.

San Onofre is a "-Tery old plant that was on the list that had denting.

However, they've only got a couple percent tubes plugged.

Where they have denting I

• it's very localized and, miraculously, it appears to _have stabilized. *

. I If you follo"{ -- this is one of the-*things I was* thinking of before when.I said that there's so many aspects that you can't really understand it.

Denting was proceeding.pretty rapidly in some localized areas, and has essentially increased n.il for the last two years.

And it makes it very difficult to explain the thing phenomenolog~.

ically, what's. going* on *.

• And there.are so many different

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I 68 consider~tions like that, that from a chemistry standpoint we have Brookhaven Lab looking at it, and *there are people, although they think they understand it, they're a*little baffled every time we find *a new piece of data.

COM.~ISSIONER AHEARNE:

Has ACRS had any comments or conclusions.on it?

MR. EISENHUT:

We met.with the ACRS on a couple of occasions and discussed this over the last couple of II years, and I

• think basically-they really didn't have any I specific comments about what's going*on.

Just comments such as, keep. us informed as *. things develop, and in general.

COMMISSIONER KENNEDY:

What's the status of the 1* 2.206 petitions before us?

'I MR. MURRAY:

We've responded to several of them,*

I Commissioner Kennedy.

MS. MOE:

There's two 2~206 petitions that are coming for possible Commission review.

On one,* the time

~xpires May 15, and on the other the time expires May 24.

And we have received another petition which will be coming which could be treated as a 2.206.

It is a petition addressed to the <;:ormnissioners.

COMMISSIONER KENNEDY:

From whom?

• Ms. MOE:

The Potomac Alliance.and three.other organizations.

CHAIRMAJ.'1 HENDRIE: *.The* previous two are 206 cflce* '7-ede'ra/ c:Repo-cte-c~. 2nc.

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• 24 25 69 petitions and the staff has them in hand.

MR. BICKWIT:

The p;evious two have been denied.

CHAIRMAN HENDRIE:

Other ques.tions?

(No response.)

Good.

We appear to have run this subject out.

• Thank-you.very much.

concluded.)

(Whereupon, at 11:20 a.m., the briefing was df.r:t:- 'Jedt:1:af cRepO'Ctt:'!4, !lnc.

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