ML20126F414
| ML20126F414 | |
| Person / Time | |
|---|---|
| Issue date: | 03/10/1981 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| ACRS-T-0832, NUDOCS 8103130492 | |
| Download: ML20126F414 (144) | |
Text
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NUCI2AR REGULATCPS COMMISSION A
m ADVISORY COMMITTEE ON REACTOR SAFEGUARDS In t le Mattar af:
SUBCOMMITTEE ON REACTOR RADIOLOGICAL EFFECTS (MORNING SESSION) 1 - 142 March 10, 1981 pgggg:
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Talachena : (202) 554-2345 THIS DOCUMENT CONTAINS 80 %L POOR QUAUTY PAGES
JWBaach ACRS 1
3/10/81 I
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION 2
3 ADVISORY COMMITTEE ON REACTOR' SAFEGUARDS 4
SUBCOMMITTEE ON REACTOR RADIOLOGICAL EFFECTS e
5 h
6 A
Room 762, b
I 1717 H Street l Northwest, Washington, D.C.
0 d
Tuesday, 10 March 19 81.
c 9
h 10 The meeting of the Subcommittee on Reactor Radiological Effects was convened, pursuant to notice at g
11 8:30 a.m., with Dade Moeller, Chairman of the Sub committee, g
12 3
presiding, g
13 PPISENT FOR THE ACRS:
l 14 DADE MOELLER, Chairman g
15 HAROLD ETHERINGTON, Member STEPHEN'LAWROSKI, Member I6 3
I. CATTON, Consultant M.
STEINDLER, Consultant h
l7 D.
ORTH, Consultant P:
F. ALBAUGH, Consultant E
IO M.
KABAT, Consultant h
JOHN C. MC KINLEY, Federal Employee 19 g"
ALSO PRESENT:
Messrs. Kelber, Silberberg, Denning, Wichner, j
1 Kress, Bell, Mynatt, Pasedag, Lee, Kuhlman, Gieseke, i
-Malinauskas, Campbell, Sallach, Elrick, and Sherry.
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1 E O f 3 I E I 3 S 3-2 MR. MOELLER.
Good mo rn ing.
The meetino will nov 3
come to crder.
4 This is a meetine of the Advisory Committee on 5 Reacter Safeguards Subcommittee on Reictor Radiological 6 Effects. :I am Dade Moeller.
The other ACFS members here 7 today with us are, on my right, Stephen Lawreski and Harold 8 Etherington.
7e also have with us a team of consultants 9 consisting of Ivan Catton, Martin Steindler, Don Orth, and 10 Fred.albaugh, plus Jile Kabat.
11 The purpose of this meeting is to discuss and 12 continue review of the NRC reevaulation of the radiological 13 source terms te be used in accidents analyses.
The meeting 14 is being conducted in accordance with the provision of th e 15 Fedaral Advisory Committee Act and the Government in the 16 Sunshine Ac t.
Mr. John C.
Y.cKinley ir th e de signa ted 17 federal employee fer the meeting.
18 The rules fer participation in tcday's meeting 19 20 21 22 23 24 25 ALDERSoN REPORTING COMPANY, INC, j
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1R. ?CELLER:
Gcod co rning.
The meeting will new 3 come to order.
4 This is a meeting of-the Advisory Committee on 5
-Re= cter Safeguard s Subcommittee on Reactor-Radiological 6 Effects.
.I am Dade Moeller.
!he other ACES members here 7 today wi th u s t.r e, o n m y right, Stephen Lawroski and Harold 8 Etherington.
%e also havs with us a team of consultants 9 consisting of Ivan Catton,' Martin Eteindler, Don Crth, and 10 Frad Albaugh, plus Milo Kaba t.
11 The purpose of this meeting is to discuss and 12 continue re view of the !!R C reevaula tion of the radiological' 13 source terms to be used in accidents analyses.
The meetinc 14 is being conducted in accordance with the provision of the 15 Federal Adviscry Committee Act and the OcVernment in the 16 Sunshine Act.
Mr. John C.
McKinley is the designated 17 federal employee for the meeting.
18 The rules for partici;ation in today's meeting 19 have been anncunced as part of the notice previously 20 published in the Federal 3egister en Feb rua ry 23, 1981.
2-21 transcript of the meeting is being kept, and it is requested 22 that each speaker first identify hims*1f or herself and i
23 speak vith sufficient cla ri ty so they can be readily heard.
24
'J e h a v e received no request fee oral statements 25 from members cf the public, and we have received no written ALCERSoN REPORTING COMPANY,INC.
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statements from the public.
2 We are here, of course, to' review in' detail.the 3 report entitled " Technical Eases for Estimatinq fission i
4 Product Behavior during I,WF Accidents."i Although several 5 members of the subcommittee have not.had time, 'I am sure, tc 8 read the re port in detail', we will be covering it chapter by j
7 chapter over the next two days.
And for members of the 8 - subecmrittee and consultantr, let me tell you briefly what I 9 hope we.will be able to accomplish.
10 Today, primarily, we will be going thrcuch the 11 rapert, as I sey, chapter t y chapter, with members of the 12 N3C staff and their consultants who prepared the varicus 13 portions.
Then tomorrow we will con tinue, and I am heping 14 we can wrap up the formal interchange with the repcrt l
15 authors.
And prior te conclusion of the subecmmittee 1
1 18 meetin; tomorrow, I want us to set dcun I nwritino some l
17 thoughts in the way of preparing a draf t report for the full a
18 committee to consider for submission to the NF.C 19 Commissioners.
20 The report reflect: a tremendous amount o f wo rk.
21 It not only, of course, shows us what it knows, it shows us 22 mucn cf what we don't know.
Eut : think the staff ices 23 certainly deserve cormendition for the effort that has been 24 put into this and particularly fer maintaininc their 25 schedule.
Thay premired uc several menths ago that it would r
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be available, the first draft, en the evening of :: arch 6th, 2 last Friday.
And indeed, it was available as indicated.
3 I think that, '!el,.you deserve, ! am sure, a lot 4 of the credit, plus your team supporting you.
5 Well, we vill move on then to the interchange with 6 the staff and the first persen on cur' agenda is the NRC-7 stsff introduction by Charles.Kulber.
8 3R. LAWh0 SKIS Ceuld I ask a questien?
9
- 33. MOELLFR:
Yes, let's take a moment.
10 MR. SILRERBERGs We are missing two-people.
11
- 23. ECELLEPs Does the subcommittee'have any 12 comments or remarks?
13 5R. LAWRCSKI:
What ever happened te the judicicus 1
14 service with which~we occasionally cot reports lika this, 15 usually, the Federal Express or what have you.
If this did 16 come out on the 6 th, it would have been nice fer some cf 17 us.
I would have had at least a week to look at it.
18
- 13. ETHERINGTON4
! am 1 coking at it for the first 19 time.
20 MR. 1AWRCSKI last night, when : arrived at my 21 hotel rocm, was the first time that I saw it.
Ind it is a 22 fairly thick report.
I knew on past occasions se did have e
a 23 such a service.
Is that a art of the tudget cut?
24
'! R.
"C KINLEYa
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- 13. CATTCF Federal Express won't make it.
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3R. LAWEOSKIt Whatever kind of service it was, 2 because it was'possible to get the stuff the next day.
3
- ! R. MC KINLEY:
Yes.
4 3R. LAWROSK!:
I must say, from what little time I S did have last night, I do agree with you, Ted, that it's a i
6 tremendous effert.
7 MR. ETHERINGTONs I do, too.
8
- 23. LAWRCSKIt Also, from a quick glancinq of it, 9 I was impressed by the amount done and what appears to me a 10 rather evenhanded treatment of the information on the part 11 of not only the NRC people but the centractor people that 12 they had assisting them in the preparation of this.
It was 13 not a one-cided a ttempt in any way, from what I could i
14 detect.
I think this is tc te commended.
15 MR. MCELLER:
Ara there other comments from either 16 subcommittee members or consultants?
17 (No response.).
18 MR. "0ELLE?s I think, th e n, why don't we furt 19 simply take a chort break until Charles ic here?
20 MR. SIL3E3EEFGa I appreciate that.
21
- !R. !'0ELLERs Because I think we're ahead of 22 time.
So let 'c juct take s break.
1 23 (Frief recess.)
24 MR. "0FLLEF:
Th = mee tine will resume.
25 ie will move forward then with an introductcry j
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statement on behalf of the.NRC staff by Charles Keiber.
2 ZE. EELEEF:
Thank you, Mr. Chairman.
3 My name is Charles Melber.
I am acsistant 4 director for advanced cafety technology research_in the 5 Office of Research.
I shall make a ver'y brief introduction 6 today of what I think is a very productive effert.
I am 7 very pleased with the work that Mel'Silberberg, Rich Sherry, 8 Walt Fasedag from NER, and.a number of otners, plus a 9 significant' number-of our centractors did.
I think it is ia to very good report.
11 We met our deadline for the final draft report, 12 and we hope you'have had an opportunity, although we 13 recognize it has been' Nrief, to review at least the key 14 portions of it.
This is a significant document addrescing 15 an issue that has attained some p rc'm in en c e, but which has 16 always been a major issue in reactor safety.
That is, th e 17 nature of the' radiological scurce tern.
i 18 Today Mel Silberberg and Eich Sherry shall open 19 our presentation with a review of the points from the 20 introduction, summary, and conclusions of the repert.
Then 21 the contractors who were instrumental in preparing this 22 report will provide details of their report which form the 1
I 23 basic for the conclusions.
24 And 7 V o ul d.
rec 0mmend that you hold the detailed 25 questions of your, review f:: the contracter prerentaticn, ALCERSON REPORTING COMPANY, INC, 400 VIRGINIA AVE.. S.W., WASHINGTON, D.C. 20024 (202) 554 2345
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since that will enable ycu to deal directly-with the people 2 who have done most of th e technical work.
We will 3 appreciate your comments and will be pleased te clarify and
'4 amplify and f urther explain any points in the report that 5-may recuire it.
6 Anticipating that no significant, errors either 1
7 omission or commission would be found in the source o f the 8 peer review, we plan te forward the rarert, as revirad, to 9 tha Commission by the end of the month.
10 I would interject one point, ene remark at this 11 point that reflects my personal judgment and feelings.
I 12 believe this issue has become politicired cut of all 13 proportion and tha t we are dealing as much with political 14 science as much as we are with natural science.
Th;r is a 15 technically scund report, 7 am convinced of that.
I t.. ink 16 that there has been very sound thinking and werk that has
'elieve that the inception of the 17 gone into it, 5"*
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18 problem by Malinauskas, Campbell, and Stratton was alec 1
19 technically sound.
Eut in between, there has been 3 preat 20 deal of political ncire and pressure breu;ht te haar.
21
- hcpe that in any review you will help us focus 1
22 on th e tech nical issuas, reientific issues that have to te 1
23 resolved and help us keep this report a high-:::ality 24 technical document.
l 25 Cur -management backs us in this.
.:e1 has i
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discussed the conclusions'of the report and its substance 2 with the management of the Office of 7,esearch.
And I 3 believe that.he has the confidence and support of all of us 4 in making his presentation.
5 I am sorry that I can 't remain with ycu tcday.
I 6 have another meeting a little further downtown to go to.
I 7 hope to be able to get b a c!r. to you later on the series cf 8 reviews.
9 So I would like tc turn this meeting over now to 10 Mel Silberberg.
11 MR. :!0ELLER :
One question, Dr. Melber.
To what 12 degree has the report already undergene review?
Could you 13 give us some idea?
14
.M E. F.ELFER:
.5e1 can give you the details, but we 15 have significant reviews, collecial reviews between the 16 chapter editors, other key consultants, and our own staff.
17
'd e have not at this time received any of the independent i
18 peer reviews.
This is the first of them.
The regular 19 research review group meeting is scheduled for next week, 20 and these two reviews, yourc and the review aroup meetings, t
21 are constant to the major independent peer review.
And I l
}
22 might say this report is cetting as hi;h a quality peer 23 review as any report I know, includinc, I wculd say, 24
~4 A S U -14 0 C.
25 1E.
A *4R O S K! :
vtu raid you are having a meeting I
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1 on.it next' week?
Were the people sent this by mail, regular 2
'm ail ?
3
!!R. XELBER Express mail.
They should all have 4
it, including the. overseas people shculd all have the 5 rapcrt.
Wa have tried to establish appropriate means of 6 communication for issues like this.
7 XR. LAWROSKIs Could we have, or is there already 8 a list sor,ewhere of the people you have asked?
9
'MR. KEL3ERs Mel Silberberg will cove'r that.
10 MR. SILBEEBERG I will cover.where they ecme j
11 from.
12
- 33. 20ELLER:
Any other questions or ccmrent:7 13
('io response.)
14 MR. 20ELLEBs Thank you.
15 ME KEL3ER:
G o o d, luck.
16 MR. MOELLEPs We will move on then to tha overview 17 and summary of the conclusiens by the report by Mal 18 511terterg.
19 MR. SIL3EEBE2Gs Thank you, Mr. Chairnan.
20 As Dr. Kelber has noted, Rich Sherry and myself l
21 will divide up the introduction, summcry, and conclusions, 22 and the summary of dats base limitaticns.
Tirst -- and we 23 really aren't goinc to dwell on those points.
! think what 24 we will be abl+ to do is iccus what we think are some cf the 25 mora important conclusion: and some of the more 1 portant A1.DERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON. D.C. 20024 (202) 554 2345
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1 points that we have found in the' study.
i 2
I would like to introduce things by summarizing j
3 some of the bsckcround, the key points that were related to 4 what initiated the study -- in other verds, the issues, 5 technical questions'that started the study -- and the basis.
6 for proceeding and then what we found in relationship to 7 those issues and questions.
And then as the rest c ' th e
- 8. morning and. afternoon avolves, we will be playing through 9 each one of-those in the varicus chapters.
10 Now, again, let me succest that it would be very
\\
11 helpful, I think, to you and us if we leave the details for 12 the speakers from the contractors.
They have, in effect, 13 done the lion's share of this work.
They are the people whc 14 have made the analyses and evaluations and calculations, and 15 they have made the conclusionc.
16 All that we-have attempted to de is faithfully 17 r+presant those conclusions up front.
I believe we have 18 done that.
So any conclusion that we will state will have a 19 basis later on.
- nd if indeed you can't find that ba sis, 20 please note that, and we will certainly try to male it 21 visible if we haven't already done Co.
22
o w, ona thinc you will note immediataly is that 9
23 we have cht.nged tne title of the re pcrt.
K 24
( Slid. e. )
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i 1-the meeting on the 6th with the: subcommittee and the full 2 committee, the consensus was that among ACES'as.well er F
3 amongst ourselves that'the title of-the report needed to be i
4 changed becausa it didn't represent the whole title 5 really didn't represent.what it was about.
This is the 6 objective again briefly stated, and that hasn't changed.
7 That has teen the same from the beginning.
t 8
(slide.)
9 A second area objective, of course, of the work.
10 was to, in addition to providing information, the best 11 technical information available, to also put tocether an.
12 understanding of what areas were there caps and where were f
13 we limited at this point in being.able to provide the best 14 technical information.
% were able to do that also as part 15 o f th e stud y, and ! think tha t 's an impo rta nt part of the 16 study.
And this was noted in your letter to the chairman.
17 (Slide.)
i 18 1R. LAW 30SK!:
In the title that you.hsve for that 19 report, you said " release."
- guess the new title, which is 20 not the same?
21
3. 5:LEEE3 ERGS Yes.
The reason why --
22
E.
LAW 30EK!:.
The release has many different 23 aspects to it and that's 24
- 93. SI1?EEEEEG:
That was a problem we had.
In 1
25 fact, we spen: come time on f.eciding, believe it tr not, l
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whc.ther to make it " release" or " behavior."
It wasn't 2 really clear.
" Release" can mean a lot of different things 3 to different people, and va tried to --
4 JE. LAWRCSK!:
1 hat did you want te have meant?
5
- 33. SIL3ERSEFG:
We wanted to state that frca the 6 time fission products are born, released f rom f uel during an 7 accident, find their way through the primary system, hev the 8 chemical behavior might change, the physical behavior might 9 change, and then if they go into the centainrent, what is 10 their --'What are their cha racteristics in containment?
And 11 then finally, knowing all that, what might be ave 11able for 12 a release from containment on contain:ent failure er en the 13 le-kage?
14 So we used the verd "be ha vior " to kind cf cover 15 the whcle thing.
16 MR. LAWROSK!:
I thought that you had. " release" in 17 tha title.
- see it is "bshavier" in the copy in f ront of 18 me.
But : thought you said ycu had changed tha titla.
19 ZE. ?IL3ER?E?G4 What I mean t was we changed it 20 from last months' title.
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21
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C'<ay.
22
- 33. 5:13ISBIEG:
'J e w, the scope of the rescrt, we 23 do emphasize intentionally the transpcrt behavic
?nd l
24 chemistry of radicieddne fcr three sort of, ! think, 25 strsichtforwcrd rassons that I have listed there.
- odine is l
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1 potentially_a major contributor to public expcsure.
It.has 2 been.the focus of analysis procedures over the pastinumber
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3 of years'.
And, as you recall, the technical issues and 4 questions raised were, most of them, en iodine.
5-(slide.)
6 And so we felt that it was necessary to address 7 iodine in particular.
However, as I tried to explain last 8 time, vithout having the results of the'information in front 9 of me -- an d ! think you will see today tha t the contractors 10 did an excellent job of really goino'into the natural i
11 fission product removal mechanisms which have also been in 12 issue, including the aerosol generation, agicmeration, and 13 settling, as well as the effects of a condensino cteam 14 environment on aerescis.
15
'! o w, in that sense, by treating the aercsols in 16 some detail to the limits cf Our ability wi thin t he sta te of 17 technology, we have, in effect, physics 117 incladad all of 18 the other particular aeroscis, as you might eypsc.
As you 19 will see lator where we backed off en the fissien product 20 species, primarily because the information was lacking, was 21 in the chemistry, the chemistry of the individual species.
22 Sc fission products, whether it's et cesium iodida or any of 1
23 tha other individual species, are treated a s cercscls.
And 24 I want to make that clear that they are coversd.
vow the individual aerscis behave phycically in 25 4
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'1 th? mix, that's going to te addresced later on.
That's 1
- 2. ancther point.
Alsc, we did'use quite a spectrum, a
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3 reasonable spectrum of accidents,.and it covered. s wide 4 range of conditions and engineered safety feature failures 5'
and degrees of core damage.
6 And we note aise that we'did not cover all 7 sacuences or a'supar-large numher.
And that will be 8 explained la ter on, too.
9 (Sli'e.)
10 Now, let me ge quickly to the four issuer that we 11 think are the basic for what we have addrecsed in the 12 report, sere the focus of the report.
The first ene deals 13 with chemical forms.
Is cecium iodide, rather than 14 elemental iodine, as has been assumed in the past, the 15 predominant radioiodine form releaced from the fuel during 16 sovere accidente?
17 The onclusion in the report is that the current i
18 data.hase, with some qualification, supports the conclusion 19 thPt cesium ic?.ide is the expected prademinant iodine form 20 under postulated licht wat=r reactor accident conditions, 21 sithouih the formation of some elemental iodine cannot be 22 precluded under certain conditions.
And people will dwell 23 on that later as we go inte chapters on chemirtry.
24 Eo, in short, this would say we d on 't think you 25 can elimina te iodine a t this point.
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1 amont, tut we don't think that iodine can be, in itself, 2 elemental iodine, can be removed from the books at this 3 point.
4 (Slide.)
5 Let me sta te -- I just realized, making my last 6 statement, I might have been treading cn requistory impact, 7 and that is the subject of another report which will address 8
this.
Sc I want to caution myself on'how far I want to use 9 my conclusionc.
10 Issue number 2, since cesium iodide is less 11 volatile than elemental icdine and is much more soluble in 12 vater, is release of iodine during po stul a ted reactor 13 accidents currently beina overestimated?
That we fcund was 14 tha t the assumed form of icdine, either cosium iodide er 15 elemental iodine, does not have a major influence on the 18 estimated iodine releace to the environment for the j
17 risk-domim a n t accidents.
And ! don't want to ge into this, 18 but this will come out later on.
Ec we don't need to ec I
19 into it.
20 And these are particularly the ones where large 21 releases regardless of' the form, cenerally early centainmant 22 f2ilura, or naar ea rly containnent failure.
And there 23 hasn't been enough time, as ! nee it, for the cerium iodide 24 form th a t is releaced into the containment, not that which 25 is in the water, to, in effect, use its new fers to its ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON. 0.C. 20024 (202) 554 2345 i
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Anc tha t 's' a simple wa y' of putting it, but'that 2
will be clarified.
3' yow,.however, for.less severe accidents,-the 4 effect of iodine chemical on'the predicted amount of'icdine 5 released-to'the environment is more pronounced, and tha less 6 c? vere accidents are obviously those whe e there is. a -
7-preponderance ef water lef t in the system > 'for example, such 8 ss TMI-2.-
So that is where the -- we think that is where 9 4t's important, the chemical form is more important.
10 (Slide.)
11 MR. 50211ER: 'And althouch you. don't really cay 12 it, ycu mean in that last centence that the effect is'ene of 13 reduction in the release?
14
.13. S!L3EEPIEGs Yes.
Yes.
I believe rc.
15 MR. ".CE11EEs You mean the effect ic more 16 pronounced, you mean in a f avoratie way?
17
- 43. C!1?IE3E3Gs In a favoratie-way.
Yes.
Thank 18 you for notinc that.
19
- 23. SHEEFY Mel, I would just like t add cna 20 thing.
For the majority of the cases f or the less severe 21 accidents, if you assume the chemical ferm of iodine is 22 cesium iodide then there will ba scre attenuation.
- Mcwever, 1
1 23 for certain specific phenomena, primarily i~. the centainnant 24 behavict of iccine, we have fcund that in certain cases th e 25 elemental iodine, the molecular iodine removal rata wculd be ALDERSoN REPORTING COMPANY,INC.
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f aster than casium iodide in aerosol form.
So it's not 2 completely straightforward that cesium iodide..is always 3 better from the attenuatien standpoint.
4 MR. Y.0ELLERs Would you-identify yourself for the 5 reporter?
6 MR. 5HERRY:
I u Richard Sherry, !!RC Pecearch.
7 MR. SIL3EREERGs. Thank you.
8 Iten Number 3 had to de with the question of 9 Have nat urs1 removal procerses been ac'equately accounted for 10 in previous and past ' studies such as reacter saf ety 11 studies?
That perhaps most severe postulated accidente have r
12 been overpredicted because there items have not been --
13 these processes have not been tak en.inte account.
14 The results of the Ctudy do not support the 15 contentien above that the ;redicted censequences for the 16 severe accidents have been overpredicted by crders of 17 macnitudes in pact studies.
For example, the analysis in 18 this re.p ort indicates that the best ectimate atttenuation 19 factor for iodine is between about 2 and 10 for the 20 risk-dominant accidents; that is, f rc 10 to 50 percent of 1
21 the core inventory of iodine cculd be released to the i
22 environmant.
Anc, sgain using the most advanced methods j
23 th1t we have and ac I will note later, really pushing the 24 sttte of the art on th e study, th e several crders of 25 macnitude just can't ha supported.
- t just doas not have a i
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'1 gcod technical ba sis.
2 If there is'information out there for something-3 that is missing that might bring that abcut and'it is not 4 obvious to'us at this ;oint, then one. vill.have te ha ve the 5 data as well =s a modeling that goes a.lon; with it that 6 allows one to include somethine-that we'really can't take 7
into account yet.
8 (Slide.)
9 MF.. LAW 3CSK':s Is tha t. question a. f airly wo rded I
10 one?
j 11 ME. FIL3EEEEEG4 Actually, they were generated in 12 two different ways.
In one, they were generated.
That 13 questien evolvas f rom the.evinson-Echm'; aper as ell as 14 from Cr. John C. S+.shr's presentation on'the 12th.
Cne said i
15 several orders of magnitude.
Another said from 1rC to 10-5, 16 I.think.
To va just said "ceveral orders of magnitude.
17 ZR. ETHIEINGTON:
Can you quantify roughly the i
18 ric k-d omin a n t accidents?
Thich ir the doninant accide te cc 19 which are thev?
i 20 ME. EIL3EFEEIGs Chay.
Fich -- that is coin: to 21 be covered by Cr. Denny but
[
22
- ?. ETHEE!NG TON :
I withdraw the questien.
Ikip l
23 it.
24 M3. 2:1?ERSEFGs F in a lly, in the letter to 25 Chairman Ahearne by Malin a u sk ar, S tra t te n, and rar;tell, a P
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very excellent point was made; namely, Question;us Will.the 2 encineered safety features, EEFs,. designed for icdine 3 contrci be effectiva and optimal for the actual-icdine
'4 behavior ra ther than the bahavior currently assumed ?
And 5 how will these engineered safaty features perform under 6 postulated severe core damage and core meltdown accident 7. conditions?
8 And the report conclusien ic'that the 9 effectiveness and performance of the different EFFS varied 10 for different accident sequences.
That is -- now, that.may 11 be a little difficult to understand, and when ! wrcte it 12 yesterday I said to myself, "No one is going to underctand 13 that."
14 But as we get into Chapter ; and you will have an 15 opportunity te see what that neans, but what it seys is that 16 some engineered safety features did very well, cthers did 17 me ?ium to low, and there wac one, I think, that war vary 18 poor.
And that's what I mean by dependinc on the accident 19 seque ce.
n 20 (Slide.)
p 21 "ow, let me ;ust ncte something about the people 22 who contributad to the report and go to the slidec.
- First, 23 I would like to note a correction on Chapter 5, a correction 24 in your draft.
In Cha pter 5 there were two chartar h:ecFell 25 co-leaders, Dick Elder from Sandia and fren Oak i
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Ridge Na tional Laboratory, dividing up the vapor-phase 2 chemistry and the aquecus chemistry.
3 I want to note that.
Secondly, it is not shewn 4 here, but I would also like to note that the Cak Sidge 5 particiation was organized and directed by Dr. Fred tynatt, 6 who was indeed very helpful in pullina together the Oak 7 Ridge work.
8 I would also like to ackno wledge several' o ther 1
9 things.
!n spite of the severe pressure for time, 10 particularly down the homestretch, ve.never received even 11 on= chone call from any of th e team about net being able to 12 meet the schedule.
I just want that te be noted for the 13 record.
14 We have also noted in the roport certain scope of 15 the limitations, some cf wnich were the results of time 16 constraints of the study.
Howe ver, we won 't
-- and I am 17 sure that our centractors are not coinc to -- use schedule 18 to qualify what they have done.
I think they are satirfied 19 that it was their best effort, and I think that everyone 20 recognizes the schedule constraints.
So we won't une 21 schedule as an cut.
22 Ihe teamwork cooperation amen; the labs was 23 excellent.
I don't believe we could have nade tha progrecs 24 we made without it.
I belisvs that in scst areas we 25 exceeded the initial 70alc we set f or curselves back in ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W. WASHINGTON, D.C. 20024 (202) 554 2345
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December when the study was initiated.
Some of the verk 2 recrosents new efforts and extentions of available 3 information.
Iet me just list some of these so that ycu can i
4 look for them as we proceed through the report.
H 5
.One war a reevaluation of fission product release 6 frsetions and rate data to yield a revised release model.
7 liew assessment of the equilibrium chemical thermodynamics 8 for cesium-iodine-hydrogen-r eam systems.
9 The firrt evaluation of the effect of cendensing-10 steam environment on aerosol behavior for a specific 11 accident sequence; namely, TM13 prime and, to my knowledge, 12 and I know the calculatione are still perhaps being made --
13 the first evaluation of' aerosol behavier for a E '4 5.
There 14 may be others that will pop up.
15 I just want to nete that most of the new 16 evaluations of analyses were develcred during the last two 17 waeks cf the etudy.
And at that time, I could sense 2 great 18 deal of enthusiasm out in the field that the contractors --
19 for the kinds of information tney were getting and soma of 1
20 the insichts they were gettinc in ?.ow thin;s were turning' i
21 out.
And I really believe that we didn't run out of time as 1
22 much as we ran out of inferation.
That's really what I 23 believe.
I believe we went right up as far as we can tell, 24 ri-ht up to tha sto:s of the state of the art and really I
25 came up acainst -- we just can't go any further, :eally.
ALDERScN REPORTING COMPANY,:NC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554 2345
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There ara certainly improv'ements and 1
2 embellishments and different ways of fresenting the data, 3 and maybe a few more calculations that we can make,,and we t
4 may indeed maka in the next week or two to ju st round things 5 out.
Put I am not all thst concecned about not having that 6 information at'this point.
7 (Slide.)
8 Finally,'just let me note co me thing about our peer 9. review process, which ! micht tell you, tock some time to 10 develep.
We are even getting phone calls from around the 11 country fr0m paopl9 Who would like a copy because they would 12 like tc,c'omment and so forth.
And ar best we-can, we are 13 sanding people copies.
I 14
'J e have indicated to them'that it is going to ba 15 di f fi cul't for them at-this point to be ;srt cf the formal 16 review process.
We welcome any commants they have, but as-17 far as meetin; on the 17th and 15th, there were going to be 18 time constrsints on just naving the people that I hava 19 listed here, cattine involved in the peer review.
20 Now, I h a ve liste d the peer reviewers by the 21 followino cate:ories, and I will try to name some of the 1
22 names in each one Of those, and I may miss some.
23 Sut on the independent revias side, we have people 24 like leo Erewer from the University cf Calif ornia-Eerkeley; 25 we have Dr. lloyd Zumwalt, prcfessor emeritus at verth ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554 2345
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Carolina State University.
We.'ve got
- ) avid Garvin, Dr.
2 David Garvin from NES, who heads up deputy director of a 3 secticn en chemical physics.
We have -- although we list 4 him also as a DOE lab reviewer -- we have Eichard Wallsce 5 from Savannah Fiver laboratories.
6 And've have-others whom we can't really now claim 7 as independent, but nevertheless they are well known in the 8 field.
And I feel that one can get as independent appraisal 9 from them as possible.
Certainly, somebody like Feb 10 Hillyer, from HEDL, who has tremendcus background in this 11 area whom we've used before on review groups.
Carl Johnson 12 from Argonne National laboratory.
Donald Schweitzer from 13 3rookhaven National labora tcry.
We've invited rave Campbell 14 and Tony "alinauskas.
And Bill Stratton has, if you will, 15 lab reviewers.
Although I muct say that in the stretch, 16 when things got exciting, ave Campbell and Ton? alinauskas 17 pitched in and effered advice and contributions that were 18 indeed very, ve ry helpful.
And, again, sno ther e xa m ple, I 19 think, of good teamucrk.
20 9e have industry revi ewe rs,
- r. 31 chard Vogel 21 rapresenting E7FI; we have Dee Walker representing 22 ' des tin gh o u s e and 775; and
- hen we have representativer from 23 GE, E E. W, and Ocmbustion Engineering.
"e have Ecbert Eit: man 24 from SAI.
We hav: invited Harry forswitr from AI.
25
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now we have five out of six acceptances, very enthusiastic 2
cooperation from the foreign countries.
We have Dave 3 Torgerson f rom AEC1 in Canada.
Brian Ainscouch frem UEAEA 4 Spring Fair Lab.
We have a Mr. Devillers from CEA, who is 5 responsible for the radiological work there.
We have a 3r.
6-Ishikawa from JAEEI in'Japsn.
And 3r. Devell-from Sweden.
7 We also will represented by federsi agencier.- We 8 are still in touch with EEFA and trying so make-contact
(
9 there.
We have NEE, of course, and 00E will te represented 10 by themselves as well as one of their labs.
i 11 I have listed as others the following:
There will 12 be an observer from Nuclear Eaf ety 0versi;h t Committee --
13 that should be -- FRDC has. teen invited.
UCI is sending 14 Gordon Thompson and 3cb Alvarez from Environmental Eclicy.
i 15 Institute has been invited and will attend.
18 3asically, then, tha t concludes ey presentatien, 17 Mr. Chairman.
18 XR. "0E1LER:
The icst synonym, or whstever you
?
19 call 1t, API, is that EPDI?
20 MR. CILEERSEEG:
Environ =entsi Folicy !nctitute.
\\
21 MR. LAVE 0SMI:
Have you asked the Academy of 22 Sciences, 54ticnal Academy of Sciences yet?
1 23
- 23. SI13ERFEEG:
I thought abcut it, and : fust 24 haven't really come to grips with it.
thin k ! ni;ht do 25 that.
! think that is a good r ug g e s ti o n.
ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON. D.C. 20024 (202) 554 2345
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F. R. ALBAUGHs Where does this committee fit in-2 this list?
3 MR. 9ILBERBERG1 Th?y would be under " Federal 4 Agencies."
5 MR. 50ELLERs Any questions for Mel?
6 MR. LAWRCSKIs Anybody from Harwell?
You 7 mentioned somebody from Springfield, but Farwell is the bic-8 research --
9
.13. EIL2ERBERGs I understand that.
Whst va did, 10 Dr. lawrocki, is we contacted our contact at UKAEA SRD, and 11 this is what was offered, and I am sure it's ceina to be 12 fine.
13 TR. MOELLER The next presentation is by Battelle 14 Columtus then?
15 3R. EIL3ERSERGs No.
I would like to introduce 16 Richard Eherry, who will do the second half.
17 ME. MCELLERs All richt.
I think when Eichard 18 finisher, ! hear the coffee perking, and we will take a 19 short Preak.
20 ME. 3HERRY:
My name is 31 chard Sherry.
I am with 21 tha.IRC Cffice of Pesearch.
" hat I had planned to do today i
1 l
22 is go over the summary.
23 1R. 20EL1ERs t a '<. e i t ac loud as ycu can, please.
24
"?.
EHE?RY:
What I plan to do today is cover tne i
25 summary, the renclusions, and the data basa limitations i
i l
ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20C44 l202) 554 2345
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1 which are presented in Chapter 1 of the report.' I won't j
2 spend zuch time on'the summary, because the individual 3 chapter needs will cover. this later en in the presentation.
4 (Slime.)
5 This is taken from the' table of centants.
It just 6 indica tes wha t. the various-charters contain.
Ch a pter 2 7 describes basically the mechanisms with fission product 8 infornation within the fuel and a number of other subjects 9 desling with the health ef f ects of radioactive materials 10 barriers, releasing these materials, et cetera.
11 Chapter 3, whera it presents a. description of the 12 accident sequences which were used in the a nalysis of 13 fission product transfer, alte, it goes into sete detail in 14 the design of various type nuclear steam supply systems, 15 containmente, et cetera.
16-Cha pter 4,
we really begin the discussion of 17 fissic product release behavior.
In Chapter a we have a 18 description of where fissien products are located in the 19 fuel rods, how they migrate, how they are released under 20 accident situations, et cetera.
21 In Chapter 5, the chemictry of cesium icdide and a 22 few Other fission productc are discussed.
There are two i
23 main subsections in this c". apter.
One is section on vapor 24 phase chemirtry, and anoth+r section, subsectica, on the 25 behavicr of iodine in aquecus solutions.
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(Slide.)
2 In Chapter 6, the transport'hehavier cf fission 3 products when they are released from the fuel and during 4
their transport through the reactor c0olant system are i
5 discussed.
Bacically, in'this study, we used the IRAP-PELT 6 cod e : to do thic analysis.
7 In Chapter 7, the mechanisms of fissien: product j
8 transport within the containment are discussed.
"he various i
9 computer mcdels that have been uned in tha study are-10 described, and then a number of calculations are cerformed 11 to determine the attention of varicus forms of' fission 12 products, particularly vapers, et cetera.
J 13 And the n in Ch a p te r 9, the effectiveneer of eight 14 different engineered safety features are addressed for a 15 range cf accidents and for diff erent chemical ferr.: of 16 iodine.
l t
17 (Slide.)
18
'Th a t I would li '< e to do now is to go into the i
19 discussion of the more important conclusieni from the 20 cha pters dealing with fission product releare and transport 21 behavier.
These began with Chapter 3, which, as you recall, 22 th+ release from the fuel.
During this study a raview was 23 mad.a of the experimental e"idence for er acainrt the 24 chemical form of iodine released from the fuel.
This review 25 ind ica ted tha t the re wa s 1..cuf ficien t evidence to make a ALDERSoN AEPoRTING COMPANY,INC, 400 VIRGINIA AVE., S.'W, WASHINGTON, D.C. 20024 (202) 554 2345
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determination one.way or another. whether cesium iodide was 2
the dominan t form released or elemental iodine.
3
- Also,:in this study the equilibrium thermodynamic 4 calculations performed in the past were to determine the 5 chemical' form of iodine under conditions equivalentoor that 6 you would find in the f uel cladding gap was axamined.
These 7 calcuations indicate the predominant form of iodine should 8 he cesium-iodide; and th e remaining cesium, which is net in 9 tha form of cesiue iodide, should be in the form of either a 10 compcund with UO2, a cesium urinate; and sise there should 11 be small amounts of cesium in elemental form in the gas 12 phase.
13 Another finding in this etudy'was -- excuse me, based on three-cf what.we 14 let me back up for a second 15 considered the best release from fuel experiments, a new set 16 of release rate estimates were made fer the cesium products L
17 based on these experiements.
Usine these new release rate L
18 estimates, total releases fcr two sccident caquences were 19 determined.
These were then compared with the celt releares 20 pr?sented in the rea ctor saf aty study.
As for the recctor 21 safety study, we found thit tha releace cf iodine in casium
. 22 during the in-vessel core meltdcwn phase was nearly 23 complete.
24 MR. 20ELlIE:
Dr. lawreski has a quertion.
25 XE. lA7EOSK :
In part, it is with raspact to your ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON. D.C 20024 (202) 554 2345 g
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Chapter 5.
To what extent did people at least icok'-into the 2 chemistry of tellurium, since it is a' precursor to iodine 3 :and, of course, its chemistry could have quite an-effect on 4 that part of the iodine that would come as a result of decay 5 of tellurium after the accident?
6 MR. SHEREYs Okay.
'4e b riefly looked at in the --
7 as I will get to ~1n the next chapter -- we looked at the 8 behavior of tellurium in a tellurium-exygen-hydrogen gar 9 system.
And ! 'will get to that.
10 MR. LAWDCSKI4 So it is'in th a t ?
11 2E. SHE39Ys It is in there.
Although ! don't 12 believe we did any esiculations of telluriun behavior where 13 we had ura nium present like you would find in the gap 14 sp=ce.
15 MR. ?E1La There'is no tellurium in the gap 16 space.
17 MR. 90ELIEE:
'4 e c a n ' t heur you.
Give us ycur L
18 name, too, platse.
19 MR. NICHNER:
Sot Wichner from Cak Ei Me.
There 20 are no calculations performed in tellurium in the cap space, 21 but, in general, the question as posed does not -- there is 22 not sufficient background infer:ation to addrers that 23 question.
And I.will repose that questien in my telk.
24
'R.
MCE11EP:
Thank you.
25
- 12. SHE39Ys Usine these release rate estimetes in l
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1 our study, we found thst'we ca.lcula t e d that the releases ci 2 tellurium actually. vary,.and strontiun were significantly 3 hioher for the in-vessel r41 ease period than we calculated 4 in the reactor. safety study.
5 Also, using the release rate estimates, we 6 calculated tha total acroscl masses released up until the c
7 time of the failure.cf the lower core structure. Jor.the 8 two cases analyzed we calculated 770 and 1aSO kilegrams
~
9 aercsols released in vessel.
10
'Jsin g a correlation developed by Sandia 11 Laboratories, we calculated the ae roscl. release during melt 12. concrete interactions for these two accident sequences, and 13 we calculated a maximum of 51C additicnal or 510 kilecrams 14 of seroscl generated durinc reactor vessel failure.
15 (Slide.)
16 The major conclusions frem *he chapter on fission 17 product chamistry sre listed hare.
We perferned a -- o r 18 Sandia and Oak Ei:!g e performed calculations fer the 19 iodine-cesium-hydrogen-oxycen system cver a wide range of 20 conditions, temperstures,-concentration of varicus species, 21 in both reducing and oxidizing conditions.
And these 22 calculations indicate that in the icdine-cesiun-steam 25 system, steam-hydrocen system, that th e dominant rpecier 24 vould be elemantal iodine, cecium iodide, and hydrogen 25 iodide.
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~1 It was found that the elemental iodine domina tes i
1 2 in oxidizing environments has been assumed, and in-reducine
- 3. atmospheres and at lower te mperaturer th e cesium icdide 4 dominates.
These calculations also indicate that the major S cesium species in the gas phase in the primary syrtem would 6 be' cesium hydroxide, cesium oxide, a nd ele m til cesium.
7 We also did the calculations for the -- to 8 investigate the predominant s;ecies of tellurium and the 9 tellurium-oxygen-hydrogen Oystem, and it.vas fcund thet 10 tellurium oxide would be the only cignificant tellu ri u m -
11 species that va found to be stable.
12 The conclusions from the investigations into the 13 behavior of iodine in the a queous system in dica te that at 14 equilibrium the iodine will exist predeminantly as icdide er 15 iodade crecies, partition coef ficien t th a t is, the ratic 16 of concentration in a liquid phase to the gas phase for 17 aqueour iodine at equilibrium will be at least 100,000.
18 Conclusions about nonequilibrium icdine partition 19 coefficient, ;&rtition coef ficiente, and no n equilib ri um r
20 iodine chemistry are subjects cf large uncertainty because 21 of the limitations in the data hace.
t 22 EcVever, sone conclusicas ca.n be drawn about 3
23 nonequilibrium iodide pa rtitlen coef ficients.
These would F
M indicate that a range of 100 tna t 's 10 to the fifth --
25
(*au7hter.)
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EE. 3HEEEY:
nct 100 and 5 -- would be.
~
1 2 ' appropriate. to these conditions, appropriate estimates for J
3 nonequilibrium iodine partition coefficients.
~4 The last two conclusions were based on the 5 assumption that I2, or.or elemental iodine, forms the 1
6 initial fo rm of iodine.
' owever, if the iodine is initially
?
7 released from the fuel as casium iodide,'then the. pa rtition 8 coefficients vould be much larger.
9 A review of the available data on the formation of 10 occanic iodide under. accident conditions, a review of the 11 test inf orma tion that is available was done.
Thir material-12 was reviewed from a more realistic viewpoint.
And bared on 13 this review, it was concl.ided that the best estimate for the 14 frsctional conversion of the elemental iodine fer two 15 organic iodide should be less than one-tenth of a percent.
16 (Slide.)
17 of f.. S TEI:iDLEE :
How did you define that partition 18 coefficient?
Completement of a gas?
19
?!3. 3HEPEY:
Eight.
It is the concencration of 20 liquid over concentration of the gas.
That includes all of 1'
21 the icdine species except the or*anic iCdine fraction.
22 MF. ETHE EI!!G T0!7 :
But in the last item, it'c 23 elemental iodino it 's not all the iodine specier, was it?
24 "E.,SHEEEY:
That was s f ractional coef firient of 3
25 elamen tal io.,ine to me thyl icdide.
+
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1 YP. KABAT:
Have.'you made an estimate the interval, 2 or on how long i t vill take for elemental.icdine tc get in 3 at equilibrium to form the Iu 35 plus IC37.
4
.MP..SHERSI:
'lo uld Oa k Rid ge --
I 5
.!R. EELLs Very little kinetic data for.that 6 reaction.
And, no, we are not prepared to make a half-life i
7 calculation on that reaction.
8
- 12. :<ABAT:
'4a ve you concidered hydrolysis P.s the 9 process involved in dissolving elemental lodine invcived 10 there?
Secausa. from these facts, it doesn't seem to be 11 clear.
12
- 13. ?EIL:
I as J. T.
Sell, fron ORNI.
%e de look 13 at the' hydrolysis of !2 species with water to produce HCI.
14 I am sorry.
He 1sked me to say'my name, and I am 15 not sure I caucht all of your question.
you havan't mentioned 16
R. rABAT:
There is no 17 HCI as one of the possibla species at all?
You just 18 conclude --
19 ME. FEIL:
Tes, we do, in Chapter 5, consider HOI 20 ss possitie species.
i 21
- 13. '< A S A * :
?ut not in the conclusions.
i 22
'I.
THE?EY:
That was the --
23 ZR. 'EIL:
They are really there in the 24 conclu:ione whare the';artition coefficients could be ss low 25 as 1C0.
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number is if HCI is present.
So, yes, they are included in 2 that conse.
3 MR. SHERRY:
This conclusion is:for_the 4-predominant species at equilibrium.
5 MR. BELLS The one, two, three -- third. conclusion 6 down is really based on only the reaction to fccm E0I.
7 MR. KA3AT:
Did you say there is coefficients for 8-I2?
I 9
L' R. SELLS HCI ir.also considered.
10
- ia. KABAT:
Thank ycu.
11 MR. MOELLER:
Ic that adequate, Dr. Kabat?'
12 1?. KABAT:
I guess we can discuss it l'n more-13 detail later on.
14 MR. XOELLF3s Richt.
We can, when the chapter s
16 comes.
16 MR. LAWRCS I:
When you don't have pa rtition 5
17 coefficients greater than 10, the significance of such 18 numbers is'not just sort of lect, tnough, when you consider 19 the effects of entrainment Or aerosols.
Fo r exa n;1e --
j 20 MR. SILBER?ERGa Mechanical.
I 21
'R.
LAWROSKI:
-- many of ur have been involved in 22 tryin; te concentrate radioactive vastes and finding it very u
23 difficult to get factors of better than 10, even when 24 rather si;nificint efferts are made to cut devn the 25 entrainment life.
ALDERSoN REPORTING COMP ANY, lNs.'.,
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I see a head shakinc "Yes" back there.
So ve may 2 not be able to take very much advantage of the last 3 mentioned, you know, in the f actors cf pa rtition greater for 5
4 cesium iodide than even the 10, a few lines abova, which 5 was the care for elemental iodine.
6
- { E. SHEP EY :
think the importance of the very 7 high partition --
8
'f R. LAWRCEK!:
1ecauce we are not dealing with a 9 quiescent system when you evapcrate, say, at reor 10 temperature s al twa t e r, you don't get very much entrainment.
11 On the other hand, when you put it at toiling, you get a 12 different situation.
13 VR.
2HIREY:
! think the importance of the very 1-4 high partition coefficient is not frcm the standpoint cf the 15 lon--ter: ratio of the amount cf iodina in the gas phase to 16 that in the sump, say, but the fact that with very high 17 par tition coef ficien t, the licuid phare would not limit the 18 mass transport and, consequently, the steam flew carrying 19 radioactive materials would contact water in th primary 20 syctAm would be limited by probably vapor phase transport 21 rather than the liquid phare.
And that ic quite important.
22 (Slide.}
voving en to Charter 6, using th trap code, the 23 24 calculations indicate that there was very little attenuation 25 o'
colecular ic?. ins during transport throu;h the primary ALDERSoN REPORTING COMPANY. INC, 400 VIRGINIA AVE., S.W., WASHINGTON. D.C. 20024 (202) 554 2345
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systra for accident sequences where tha primary system was 2 dry.
However, calculations indicate if the flow path would J
3 ' _ con tact water, f or exa mple, in'".YI-2, where~the flow.went 1
4 through the -- where the steam. flow went through a partially 5 water-filled pressurizer during escape into the containment, 6.then through. the very high attenuation f actors of iodine 7 from within tha primary system, mostly the IV transfer to 8 'the liquid phase.
a 9
It'wss.also found that the attentuation of cesium to ' iodide was high for accident sequences not involved in a-11 full core melt irregardless of whether there was water in 12 the primary system or whether the primary system was dry.
13 However, for accident sequences that led to full 14 core melt, thare was lesc attenuation of cesium iodide.-
l 15 This was primarily due to the formation of large quantitier.
16 of serosols onto which the cesium iodide would deposic.
17 rather than ento the walls.
Cnce en the aercscis, it would 18 the n be transportec with the steam flew in the aerosols into 19 con tain e.ent.
20 "P.
CATTCNs
!s much attention given to the event 21 faed sequence?
22 4R. SHIIEY:
Event feed?
2 23
"?.
CATT0F:
Yes.
24 MR. SHIFRY:
Yes. ue 25 "3.
CA!TCE:
Do these conclusions hcid for Event
)
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V?
2
%E. CENFI.NGs Richard Denning.from Battelle.
3 Actually, we 1 coked at Event V more from the 4 contsicment aspects than.from the primary system aspects, 5 although the pipe break accidents tha t we locked atiin 6 Chapter 5 on primary systen transpcrt would be applicable to 7 event 7,
too.
And the indications would be that there 8 wouldn't be much attenuation in the. primary system.
9 dE. CATTCNs Okay.
Thank you.
10 ME. SHEEBY Ckay.
Using the results from Chapter 11 5 on the fission prcduct chemistry in the gas phace in the 12 thermal hydraulic calculations that were done during the 13 study, several additional conclusions could be made abcut 14 the dominant form, the expected dominant form cf iodine.
15 And because of the I concentrations of ficsien prcducts and 16 the release conditions during the core region, evan though 17 it is fairly high temperatures,, you would expect that 18 cesium iodide would be the dominant form near the core.
19 As the flow leaves the core sres out into the 20 prima ry system and is diluted by additional steam flow and 21 is cccled, cenium iodide stability would be -- well, cesium 22 lodide would again be favored because of the lower 23 temperatures being in the le sser a tnecphere.
24 (Elite.)
25 he Onclusiens regarding the behavior cf fission F
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products durinc transport thrcugh.the containment are that 2
the. cVerall attenuation f acters, the overall remeval cf i
3 iodine in the containment was not drama tically diff erent 4
whether the iodide would.he.in the' form of. particulate 5 cesium icdide associated with other' aerosols, 'of course, or 6 whather it'was in the form of elemental molecular iodide.
7 Tor the cost severe accidents we-lecked at,' that I 8-term the " risk-dominant accid =nts," those being' accidents 9 where there is a core melt event, the containment engineered' 10' safety' features fail to oparate, such as the containment '
11 spray systems and eventually the' containment fails, under i
12 these types of accident cenditions, th e predicted 13 attenuation of iodine was an the order of 50 percent, 14 whether it was in the form cf an aercsol or a :clecular 15 iodine.
16 This calculation was made for the large dry 17 containments, such as Three Mile Island, comparable 18 attenua tion f actors fo r boiling water reactors.
And ice 19 condensor containments were also sddressed.
%a used the 20 NAUA ccde to evaluate the offect of steam condensation on 21 aerosols 'or the TX1E rrime se: uence, which will te 22 disucssed later.
23 4 :cund that the effect of steam -- we considered 24 steen condensation.
There was an additionni ettentuation on 25 the order of 20 percent due to the cendensa tion of steam on ALDERSoN REPcRTING COMPANY,INc.
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the aerosols.
2 For a severe core damage accident'which we 3 analyzed, which was characterized by having apprcximately 50=
4 percent of-the core melted' the late ICCS injection, no 5 containment f ailure, add the engineered saf eguards in the 6 containment opearable, we calculated attenuation facters of 7 greater than 100,000 fer the containment for all the fission-8 product'cpacies we included in the analysis, which was fer' 9 essentially everything except the noble gases.
10 ME. ETHERINGTON :
Cn the first item there, does I2 I
11 imply wi th asso,ciated organic iodide, or is that just 12 elemantal iodide?
13 MR. SHEEEY:
That was just the va por, the 14 elemental form.
15
' ?. ETHERINGTON :
It did not include crganic i
d i
16 iodide?
j 17 Y. E. SHERRY No.
8ct-this one.
Gases.
18 ME. CATTON:
Shculdn't there bt a fifth 19 conclusion?
" hat is, that we don't know the 20 thcrmonydra ulics really w=11 enough te do a sound det on the 21 rest cf the calculations?
22 ME. CI15EE EEG:
Th=. t 's the sixth, : think.
That 23 is th e sixth and seventh.
24 MR. EHEREY:
Th ? t 's -- ! h a ve included that under 25 data ba se limitations.
- t doesn't shcw up as a conclusion.
t 1
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Eut, yac, that is a. valid conclusion.
2 ME. MOELLER:
Mel.
3' MR. EILEEEEERGs-let me 4ust note I think that is 4 a valid conclusion, really for six -- better for.six than 5 seven, I believe, for-condensation.
Thank you.
6 (slice y 7
MR. SHERRY:
I would like to point out some major 8 limitations on tha scope of this report.
First of all, we 9 did not ?evelop a new set cf quantitative source termr for 10 release of radioactive materials from the plant such as was 11 prssented in the reactor safety study.
As.?pl mentioned 12 previously, in some cares we took a close look at the 13 chemistry of the fission products other than cesium and 14 iodine, although these other' species were treated as in the 15 bulk of th e aerosols.
16 We only looked at a limited set of the postulted 17 sccident seq ue nce s.
Several potentially important 18 mechanisms were iden tified during the rtudy which, because 19 of a lack of any data at all, we -- ycu know, these are not 20 evaluated for what the effect of hydrogen hurn in 21 containment would be under tha physical and chemical 22 prCducts would be in t.a containment atmcsphere er settling 23 onto surfaces within the containment.
24
E. h0E1 LEES Your first liritation listed on that 25 chart, you a rm simply sayin; to us that you either give us 1
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1 more confidence or less confidence in what we have been 2 doing.in the. cast, but'you don't really cive us a set-of.new.
1 3 source terms; is that it?
4 MR. SHERRY:
Rich t.
We take a look at the 5 iniividual mechanisms and point out what we f eel are ' the
(
6 best models and do some c'.lculations with these models'to 7 provide some insightc into what possitie attenua tion.
8 But because of the limited amount of time for the i
9 s.tudy, we did not do a systematic calculaticn cf where we l
10 first calculated the new releare rates from the fuel and 11 then to the primary system calclulation and then the 12 con tainment calcula tion.
And since we did not de this, we 13 don't -- we dca't have -- We didn't have any way to generate 14 th new source terms systematically fe r each accident 15 sequence.
16
!!E. 2GE11EE:
hel.
17 M. R. SIL3EEEEEGs
! voul1 j uc t add tha t when we 18 first started this ctudy, we knew that we were not going to 19 be able to come up with a new cet of source ter s, but we 20 would hope -- we had hoped -- that we would at least provide 21 enough information, enough e val ua tion ana ly cis, to previde a 22 goed peint of departure in which to proceed in the future to 23 get those source terms.
24 And
- micht say T hadn't cri;inally thought that 25 we would even get this cloca te that.
A r. d we did.
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such, at-this' point we are not goin? te recommend in that-2 context of reactor safety etudy sayinc these are the kinds 3 of release rates factors we went to use for release to-4 containment.
One would want'to go from the leginning to the 5 end again and add them all up and see what one gets.
6 MR. E THE ?.INGION :
Cn the last item on'the previous 7 slide, was there any consideration of any qualita tive 8 consideration of what a hydrogen deflagration might do?
9 MR. SHERRY:- Yer.
10 MR. ETHERINGTON:
rid you look at it and say, 11 "W=11, we can't de anythinc cr" --
12 MR. SHERRY:
Well, we did take a brief icek at 13 it.
We asked Tr. Salinausk as a t Oak Ridge to see what he 14 thought about it, and he indicated that he didn't feel that i
15 it would be verth pursuina right now because --
16
'! R. ETHERINGTON:
Nould you speak a little louder, 17 please?
18 MR. 2HERRY:
Ia.m scrry.
Initially,-we had a sked 19 Dr. alinauskas at Oak Ridge what his thoughts were on this 20 surject, and he concluded that bacically, with so little 21 inform? tion around to maka any estimates, it would not be 22 worth the effort right now to purrue that.
23 1R. ETHERINGTON:
His ooinion wa it var not 24 impcrtant?
That is really what I was trying te drive at.
25 1R. SHEERY:
I ton't believe it was his opinion ALDERSoN REPORTING COMPANY. INC, 400 VIRGINIA AVE., S.W WASHINGTON. D.C. 20024 (202) 554 2345
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tha t it was net important.
2 FR. ETHERINGTON:
I reo.
3 3R. ZOELLER:
He said we just don't know how to do 4 it?
5
- 33. SHERRY:
Right.
6
( Sli.i e. )
7 Another limitatica in the scope of this report is s
8 that we did not evaluate the pa st reactor accidents or the 9 destructive tests with the models used for the analysis in 10 this report, for a number of reasons.- Although we co uldn ' t 11 examina the effect of these limitations rigorously on our 12 conclusiens, we don't believe that betause of these 13 limitations our conclusions are in error by large amounts.
14 hE. COELLIR:
How much more do you have?
I knov 15 ve'are runninf a little behind.
16 ME. SHERRY:
I have a number of slides en 17 limitations in the data bare 4hich can be taken at a later 18 time.
19
?! E. SILRERBERG:
At the end.
t 20
'! E. SHEFRYa-So ! can conclude my presen ta tio n i
21 richt nov.
22
- 13. 20ELLER:
All right, maybe we should do that.
4 23 MR.'SILBEREERG We can have that later.
24 1R. %INCHER:
Ech :Jin cher f rom Cak Sidco.
I would t
25 like te questien your definition of the, term ALDERSoN REPORTING COMPANY. INC, i
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" risk-dominating sccident."
It's aflittle bit differentL 2-from what thcucht it'would mean.
You're usinc it, it i
~
3 seems, synonymcusly with " severe' accident," whereas I-4 thought'a risk-dominating accident could'be either severe or 5-a less severe accident ~ as lonc af it's near the pretability r
6 consequence area.
7 It's a fairly important point, because you make 8 sor.e conclusions regarding the risk-dominating accidents, 9.and ! think perhaps What.you really'mean is " severe."
10 F. R. EHERPY:
Well, in the reactor saf ety. study, if 11 I am correct, the risk-dominant accidents, irregardless of 12 what sequence they. follow, wo uld always have certain 13 cha racteristics. 'Among these were abcVe-grcund-containment 14 failure or at least failure to isolate the containment or 15 sonathina involved 16 ME. L A'#ROSKI s leuder, please.
17 YP. THERBY:
I ar scrry.
As I was sayinc, the 18 risk-deminant accidents, irregardless of the sequence in'the 19 rea ctor -- as anslyred in the reactor safety study -- a lwa y s i
20 had certain characteristics, such as abova-ground 21 atmospheric release, centainment failure abcva-grcund, core i
22 meltdcun an d, in mest cases, failure cf the centainment i
23 engineered safety features t0 operste.
24
.Ihat'is what I maan: when ! said " risk -d omina n t,"
25 and ! was not referrinc to any particular accident ALCERScN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D C. 20024 (202) 554 2345
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1 saquence.
l 2
MR. tiINCHER:
If I.might, tha-point I am driving 3 at is that s o t:e of the conclusionc tha t were arrived at de 4 in fact effect the risk curve at the low-consequence end, 5 whereas the way in whi ch the conclusion was statei, that did 6 not happen becausa of the dif f erence in definition of the 7 term " risk-dominating accident."
I am not sure I made my 8 point clear.
9 It is possible, from the conclusions.ac. stated, 10 that the consequence of less serious accidents are indeed 11 reiuced; th eref ore, in my review of what " risk -d o min a tin g 12 accident" means, I would say that the risk har in fact been i
13 diminished of the low-conccquence accident.
14
R. 3 ELL Amen.
15 "R.
"0ELLER.
You are saying also that if that we 16 are to cive our attention to the note important contributors 17 to risk, we will look at the bigger-risk accidents?
18 "R.
ALRAUGH4 No, not necessarily.
19 3R. MOELLER:
Any other contants or quartions at i
20 this peint?
21 (No responsa.)
22
'.' E. XCF1 LEES I think we should s11 recognize, of 23 course, that when we cover the individual chartars, wo will s.
24 have an opportunity to go into each of thesa items in more f
25 detail.
g l
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l' Okay, let 's take ten minutec.
~
2
-(3riaf recess.)
3 MR. 70ELLEPs The meeting will come to order.
4 We are in a.very poor room, fron the standpoint-of 5 hearing what is being said..
And we have a high. level cf 6 background noise.
Fo we ask and plead.with everyone to 7 identify yourself and to speak loudly.
8 Also, for the various laboratory people who are 9 here who have worked on various chapters of the report,.I 10 would encouraga you to raise your hand and contribute if you 11 have a comment, because we are here to learn and to de the 12 best job jointly that we can.
To we very much encourge you 13 and invite your comments.
14 We will move on then to the :atte11e Columbus 15 presentation.
You are Mr. renning?
16 MR. PENiiING s That'c right.
I sr. Richard Eennind 17 from 3atte11e Columbus.
And : have worked on the accident 18 sequence identification with ; ark Cunningham cf the NEC.
19 The reason that va had to select specific accident 20 sequences here was to provide a context within which the 21 study would be performed.
Thet ir, the evaluation of the.
22 accuracy o# the data base, tne evaluation of the analytical 23 methods depende upon which accident secuences one is 1. coking 24 at.
And so we had to define accident sequences which would 25 be used in the different enacters and in each of the re sult s ALDERSoN REPORTING COMPANY,INC.
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i type.of chapters.
Chapters 2 and I, cf. course, are really 2
just background.
3 (Elide.)
4 Chapter 4 and the estimation of the release of 5
fission products and aerosols from the fuel, we had to 6 define some accident sequences there'to help the'Cak Eidge
~
7 people in doing this.
There ir no' explicit consideration of 8 accident sequences.in Chapter 5.
However, there was 9 iteration between Ch a pte r 5 _ a'nd Chapter 6.
'" hen we locked 10 at the prima ry syrt'em transport behavier for different 11 accident sequences, we th en told.the people from randia what 12 regime they should be lookinc in with regards to H2O ratics, 13 fission products, H20>ratics to come up with the chemical 14 form.
15 To they selected their regime bared upon the 16 snalyres here, and th?n later, after ve had done the primary 17 sy tem transport analyses, we vent back and looked to see i
18 what wa thought the chenical form cf the fiscion products 19 would be, based upon those results.
20 And the pa rticula r accidents are selected for 21 Cha pter 6, and in a second ! will explain the backt.round 22 behind why we chose-the ones we chose for Chapter 7 on 23 containment transport, and'than in Chspter E we really went 24 back and looked at the results from thece other chapters.
25
( S l i.i e. )
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The criteria for selecting the accident-sequences 2
were, first o f all, we wanted to cover a broad spectrum of 3
accident sequences.
We realized, thouch, it.couldn't be 4 comprehensive.
3ut we wanted'to try to ccver as broad a 5 spectrum as we could.
We wanted to.lcok at real accident 6 sequences.
And our intent in the analysis.was to ana17:e 7 thase realistically.
8 And there were not intentional censervatisme put 9 into the Lnalyris.
9e wanted to include a range of possible 10 conditions in the reactor coolant system and in the
^
11 containment.
is wanted to examine the influences of the 12 containment design and encineered safety features.
13 How, there are a number of different areas within 14 the plant where there are accumulations of. fission products 15 that can be released to the environment.
Ne decided to'look 16 specifically at damage to fuel in the operating reacter 17 because of the inventory of fission products there.
There 18 are like 5000 curies of fission products in the waste ias 19 stcrage tanks, about 5000 curies of fission products in the 20 teacter coolant system dissolved there.
There are about 2 1
21 times 10 to th e se ven th curies in the rpent fuel storage 22 pool.
23 These are ductile numbers, but they are creater i
24 than 10 to the nin th c urie s f issic.- ;rCducts within the fuel 25 of the operater reactor.
To this is where there is a l
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potential for's major release, and-so.this:is where we 2 focused in our study, not to cay that the accidente involved 3 in th e o thers aren.' t import an t, but this is what we decided 4 to look at'in this.particular study.
5 (Slide.)
6
'Je divided the accidents up into two categories:-
~
7 onas which involved minor or no fuel demage; and then ones 8 that involved severe core damace.
- he minor or.no fuel 9 damage sequences are the types of sequences that are 10 typically analyzed in safety' analysis reports or, if one is 11 f amiliar with the' AFS clacrification of accidents, their 12 categcries i throuch 4 defined there, these would be the 13 condition a type of accidents.
Realictic accident sequences 14 in which one might get claddine damage, that ir the type of 15 thing that is involved there.
16 "R.
LAWEOSKI4 You use the number of 10 to th e 17 ninth as the inventory of fiscion products.
18 TR. TE3NING:
Yec.
19
/ R. L A'iEG5KI s Yet I ces numbers that are at least 20 a facter of 10 higher than that quoted for a thcurand 21 megawatt electrical.
22
E. TE'f3INGs The value for a tho usa nd -mega va tt 23 electrical reacto r -- ra th e r, 1200 mecavatt electrical 9
24 reactor that 'Tandia analyzed with cricin was 1.4 xT 10 I
1 25 think'that's a good number for the curies in an cperating 1
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reactor.
2
':2. WINCHE?.
At what time?
3 "E.
DENNING:
This was after three years of 4 operation, I believe.
This wa immediately.
Zero time.
I 5 am not sure where your 10 to the tenth would have come 6 from.
7 da lA4RCSX!:
%=11, because I recall a ; aper by 8
Dr. Weinbero in which he states an inventory of 15 tillion 9 curies.
10
- 93. DEN 'J I N G :
15 billien?
". think that 1.5 11 billion is really the better number.
I t.[.i n k there is an 12 error of a factor of 1C there.
However, I don't'think I 13 would like to challenge Dr. 'ieinberg.
14 (lauchter.)
15 MR. OENNING:
Then the other category was the 16 severe core dtr. age accidente.
The prcblem we have run into 17 here is semantics.
People ure " severe core damage,"
)
18 "degrded core," then the " core meltdown."
Some people ure l
1 19 them for different purposec.
! use he re "degradea core,"
20 things that are mora sever? than clad damace, but *ct going 1
21 to ro.plete core maltdcwn.
'ut that is not universally 22 ured.
23 In this report, when we refer to "d eg ra d e d core i
24 sequences," there are thines that are more revere than j
25 cladding danaco but don't :o to complete core meltdown.
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Now,' f or these cevere core damage accidents, there 2 are characteristics of them that are pretty much all the 3 same, that is, there hais to be a heat coolant imbalance.
4 Either the heat generation rate has to rise and exceed the 5 capability'of the coolant tc take away the heat such as.in a 6 rea ctivity accident, or-you have to degrade the hes t 7 transfer capability of the coolant such as by loring.the 8 coolant.
And it is really the second type that is primarily 9 wha t we have looked at in this study.
10 This seems to be the-more likely type 11 (indicstina), although the characteristics aren 't 12 a ppreciably from between these two different typan of 13 accidents.
?ut this is nere iccs of coolant type of 14 condition thera-leading to degraded core conditions.
15 (Slide.)
16 MR. STIINOLZ?:
Are you planning to address at 17 some later time the diff ere nce in the chara cteristics 18 between the first and the second of those tuo last items 19 that you indicated?
.fR. DENNINGs Yee.
T. e t ne cc back and make sure I 20 21 understand.
- am going to go through now and tell you which' 22 accident sequences we analyred here, here, and 'ere 23 (indicating).
.a nd I will tell you whtt these sceident 24 sequences looked like.
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he will explain what the fission product transfer was.
2 MR. STEIVDLER:
That's not what I had in mind.
I 3 Under your last heeding there, the severe core damace 4 sequence involves one of'two situations.
Now, down one 5
further --
1 6
MR. DENNINGs Here?
Yes.
t 7
MR. ETEINDLE?s It's the.first one that 8 constitutes the largest ancunt of accumulated data on the 9 reactor accidents that have lad to people becoming 10 interested in this. whole problem in the first place.
And if 11 there is a difference in fission product behavior with 12 release characteristics, et cetera, then lookinc at the 13 models'that are prepared on the basic of the second item and 14 comparing them to th e da ta, wha t we have is a difficult 15 itam.
It's the difference between the twc ! an 1 coking 16 for.
I 17 MR. DENNING:
Let me see if I understand.
You are 18 saying that reactivity excurcien accidents are the ones we 19 have the most expSrience from?
20 5 ?.. STE!NDLIPs A part of the experience.
That's 21 ri-ht, 22 "E.
OENNING:
It certainly is a cart of the 23 experiance.-
"ow, there are a number of reasons why we 24 didn't select reactivity excursion accidents specifically te 25 look at.
One of them is that typically they happan in I
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?
1 water-bounded environments,-se that the releases are going 2 going to be into -- eventu ally wind up into water.
And I 3 think in. that cense these accidents are going to look 4 eventuallya let like sn accident that we analyed right here 5
(indicating).
6 As far sc what'-- it also turned out that 7 reactivity excursion accident: didn't-look like they are 8 risk-dominant.
That may be unfair, because ! think we 6
9 overplay this question of risk-dominant.
But in WASH-1400 10 it didn 't look like the rod ejection accident, the control 11 rod dropout accident, are really tha t likely, particularly 12 in ccmparison to the expected consequences.
13 So I am afrsid that we may not answer all the 14 questions that you might ask in thic regard and I think at 15 tha moment, th en, all : can say is that you might save your 16 comments until afterwards and perhaps make some suggestions 17 in th a t regard.
Just a final comment.
Iooking at 19 the exterience of those acciden ts that are cited in one of 20 the reports that inry circulated to.ur, which ! can't cite 21 to you, it's a sequence of experiences which indicate that 22 noble gas release as well as iodine release and rc on.
I l
1 23 gather then tnat we need to look st.the consequences of 24 these accidents with creat caution because they are in fact 25 different frca the host transfer capability.
They're the ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554 2345
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ones I am~ focusing on.
2 MR. DENNING:
I think the most' importan t thing 3
there is that. there aren' t many accidents that have happened
^
4 in PWRs or EWES of'this type.- Okay.
I think that is the 5 big difference as opposed to the difference between do they.
6 look like this type or that type (indicating).
7 I think the biggest thing isJwere they really in 8 similar ceometries f or simila r beha vice to what one.micht-7 9 expect in a real operating reactor.
.10 (Slide.)
11
'ow, we only conridered one of the minor or no 12 fuel type damage sequences.
This was a" large-pipe-break 13 accident with the emergency core cooling system operating as 14 expected.
In this particular accident sequence, you would 15 expect some cladding f ailure, some release of gap it inventory.
And we only looked at this particular accident 17 sequence with regard to this primary system accident 18 behavier; we were lookinc to see hcw much retention of 19 radioactivity will we expect in th e primary system.
3.nd the 20 results will be discussed later.
21 One would expect in this particular accident 22 sequence a very small relense from the containment.
23 (Slide.)
24 The degraded core raquences are really very 25 difficult to characterire, because they involve partial ESF 3
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performance.
In general, the reason you cet into a degraded 2 core condition is because there has been aither tha failure 3 of an engineered safety feature or the delayed performance 4 of an engineered safety feature.
And the the thing that 5 arrests it short of full core meltdown is that the 6 engineered safety feature must have at least worked to some 7 degree.
8 So we are faced here with quite a broad rance of 9 possible releases to the containment, and they rance from 10 things that are chactaristics of these minor fuel damage 11 accidents all the way up to accident: that are tyrical of 12 the full core meltdown accidents.
13 Se looked at two particular conditions, because it 14 seemed to us that there were wo conditions of major 15 interest.
Cne of those is release into water-rounded 16 primary systens, such as as ha;pened at TM:.
At T"I, the 17 core was uncov= red, but there was always varar in the 18 pressuriner.
For the iodine to get into the containment 19 atmosphare it had to ;o throuch water.
So this was the 20 cond.ition that we wanted t: lock at.
21 n the other hand, there a re also sequences ruch 22 as pipe braak sccidents where ther2 could te a dry pathway 23 to the containment, and one micht expect a lar er transport 24 of radioactive :sterial to the containment under those 25 conditions.
i l
ALDERSON REPORTING COMP ANY. INC.
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So the two sequences we 1 coked at were a TMI-like 2
accident, and that is wha t this stuck-open relief valve with 3
partial ECCS operation is.
It's not cupposed to be a moexup 4 of TMI, end there are some assumptions in the analysis that 5
are different from TMI.
It's ruppcsed to be characteristic 6 of a spectrum cf eccidents of this type.
7
'd e looked at fissionproduct transport thrcugh 8 water to the containment atmosphere in th it case.
And we 9 also wanted to look at trcasport through systems like the 10 letdown system.
And we did it within the centext of this 11 accident equence here.
12 Then the other type was a lar e pipe-break 13 accident with delayed ECCS injection.
In this pa rticula r 14 cace, the ECC system, the active ECC cystem, was delayed 16 15 minutes.
When it came on, the core was 50 percent 16 core-mciten or 50 percent tf the core had been melted, and
]
17 thun it rapidly, or ;resumably, recovered the core, and 18 arrested core meltino at that point.
19 There was a dry pathway to containment durine the 20 period of core un co ver y when the damage was occurring to the 21 core.
Note the similarity here to the T:0 assentlies.
50 22 percent relearc of iodine in the T!D ccsumptions.
Now, this 23 ic not a desian baris accident; this ir suppocedl. a 24 realictic type of accif.ent tha t locks somethinq like the T:D accumptions!.
25 ALDERSON REPORTING COMPANY, INC, 400 VIRGINIA AVE., S.W., WASHINGTON. D.C. 20024 (202) 554-2345
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.1
-So if you want to see what would something look 2
like, the TID assumptiens look like, within the context'of a 3 realistic ' accident requence, then this is somewhat-like 4 that.
5 (Slide.)'
8 Now.I am going to be talking'about core-meltdown 7. sequences that we analyzed.
~4e started off by looking at 8 - release from the fuel.
This was input required for Chapter-9 4,
and we looked at two specific cases.
A ra pid f uel heatup 10 cace, where the core would. melt down very quickly, and then 11 a delayed core meltdown case where core meltdown was delayed 12 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
13 I won 't po into the crecifica of this'particular-14 accident sequence, but meltdown doesn't really eccur until 15 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> af ter chutdown.
Ic it happens over a more 18 protracted tine pericd.
17 So wa used these two sequences here (indicating) 18 to give us the spray.
19 YR. CATTON:
The first one, ra pid fuel heatu;,
20 that is still slow relative tc-the chemical kenetics?
21
E. OENN!NG:
! think this is true, because thic 22 is like 20 minutes to m el t dcwn the core.
f 23 v3. r!I,3EEEEEG:
ei ht.
24 25 '
i 2
ALDERSoN F' PORTING COMPANY. INC.
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(Slide.)
]
I 2
Then we moved on to transpor't 'in the primary
~3 system.
4 Now, Appendix A has a generic catagorization of 5 accident sequences.
The intent there is to try to cover a-6 broad spectrum of possible conditions so th u t we cculd show 7 that the specific ones that ~ we choce were characteristic.of 8 ths. entire spectrum.
9 In Nhere we looked at the behavior"in the reactor 10 coolant system and;in the' reactor cavity.
I won't oc into 1
11 this ca tego rization tha t we went through th e re.. E u t. th e 12 principal variations that we saw between the sequences were 13 in the flow path to the containment, which is different for.
14 different sequences, the thermohydraulic conditions in the 15 flow path, the pressure during core seitdown recognized that 16 in somo sequences the pressure in the prima ry system ca n be 17 post-atmcspheric, such as a core. meltdown that was initiated 18 by a large pir,e br?ak, or it can be a f ull systen pressure 19 like 15 bars in some transient accident sequences.
20 And what we wanted te icek a t were th e se 21 conditions and also the hydrogen-to-exygen ratios.
'd e h av e 22 both potential f or oxidizing or releare in the a t:csphere 23 and the fission pr oduct-tc-u2C r?,tios.
24 (Slide.)
25
- n :enersi, we saw two stages of core moltdevn 1
ALDERSoN REPORTING COMPANY. INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554 2345 1._,.
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1 here.
And the first stage, which is before pressure vessel 2 melt-through, there are two primary release. pathways.
Tha 3 core is heatinc up here (indicating) and releasino the 4 radioactivity and relating many of the transient accident 5 sequences, the pathways at the top of the core to the hot 6 leg and the pressurizer to 'the reactor coolant drain tank 7 and into the containment atmosphere.
8 If you'have a pi;e-break accident, then you go-9 from the top of the core to the loca tion of the pipe treak.
10 Now, that location can be quite a bit different for, like, 11 example, like it can he in the hot leg; that's a ;rettf 12 direct pathway.
It could be in the' cold leg and require' 13 t:2nsport th ro ugh the steam generator, which could give you 14 quite s difference as far as daposition within the primary 15 ' system bef o re release to the environmant.
16 The maximum temperatures that ve saw for core melt 17 during this stage were up to 1500 degrees C, leaving the 18 syntan in a hot leg break.
The rance cf temperatures 19 throughout thin system could be from something like 2000
[
,20 degrees centi 7rade in the upper plenum down to 250 degrees 21 centigrade far down the pathway system.
22 (Slide.)
23 Then af ter you ha ve pressure vessel melt-through 24 and the core is attacking the concrete, ycu can have flow up 25 to the containment atmosphere.
ALolRSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554 2345
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There are also some other potential flow paths, 2 such as through the keyway back up to the containment 3 atmosphere.
4 I guess-I forgot to mention that I wanted to, in-5 t h e. t earlier phase of the accident tha t I went into before, 6 it really is pretty unlikely that you are going to have air 7 ingress into th e reactor vessel.
You are almost certainly 8 going to have a reducing environment.
One can dream up 9 conditions where you can'have air ingress, but they look 10 lik e th e y have very remote possibilities.
11 In this essa, took, it icoks like at least in this 12 portion of the transport pathway, that you are going to have 13 re'ucing conditions.
The conditions are going to be it dominated by the products of decomposition of the concrete, 15 hydrogen, carbon monoxide, carbon dioxide.
16 femperatures in here (indicating) are going to 5
17 rsnce from 1200 degrees centigrade to as high as possibly 18 2200 degrees rentigrada.
There are some conditions where 19 you mi;ht have sprays opertting in water flowing down into 20 the cav it ?, and then thinre would be pretty cool in tha 21 cavity.
22 There is some po:sibility for s flev gathway 23 coming dcwn t h e-keyway and up aroun d
- .h e ve ssel, and 9e 24 don 't know wh othe r tha t would actually be realired in an 25 accident whare oxygen could b2 brought down in here ALDERSON REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., W ASHINGToN, D.C. 20024 (202) 554-2345
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1 51-1 -(indicating).
I think it'is unlicely, but 1lt is comething 2 tha t - we will' have to look at f urther; in the f uture.
3 (Slide.)
4 The specific secuences.that we looked at were for 5 tha 'prassurized water reacter, a large-pipe-break accident 6 with failure-of the ECC system, and.here we looked at both 7 hot leg'and cold leg breaks.
And then f or transient 8 accident, we looked at less of heat removal capability, the i
9 T.w 3 prime accident.
Thi-is according to '4 A CH-1u00, one of 10 the more important accident secuences.
11 "R.
CATTOU4 Ctn you tell me again why you didn't 12 look at the V sequence?
13
".E.
PENNI3G As far as the primary transport is 14 concerned, you will see that en containment we did.
I 15 t ho ug h t that ac f ar as looking at the primary system 16 deposition, that the V secusnce would 1cok somewhatD11ke 17 cold leg break.. It doesn't icok exactly like that, but it 18 looks somewhat like it.
And I would expect similar orders 19 of magnitude certainly of deposition to occur at the 7 20 sequence.
21 And then, in the boiling water reactor, we looked 22 again at the large-pipe-break accident with failure of the 23 EEC system.
?nd the transient we looked at here was failure 24 tO sCraa.
25 fSille.)
ALDERSoN REPORTING COMPANY,INC, 400 VIRG6A AVE., S.W., WASHINGTON. 0.C. 20024 (202) 554 2345
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iext,'we looked-at the transport in the
[
'2 con t ain tm en t buildino.
F 3
(511de')
4 This shows a large high-pressure containment 5 desien.
I have shown in red the-envelope of the. containment 6 (indicatinc) so we can see that boundary..'And then the 7 important. systems here, and the large high-pressure system 8 are the spray systems and the filter systems.
'nd. I ha ve to,
9 take credit for that artwork.
10 (Lauchter.)
11 (Slide.)
12 The perticular accident sequences we looked at i
13 then were ones with the sprays operatino or nonoperating.
1 14 There are some cases, there are some desiens where there is 15 fil te red recirculation.
This is not typical, tut'we did
[
16 look at a case here (indica ting ).
I i
17 So the case witnout the cprays operatinc was TM13 18 prime, transient with loss cf containment heat rencval 19 capability.
And this ic the sequence in which cne would 20 exrect early containment failure, early a t:c sp h e ric 21 con tainmen t failure.
In fact, possibily right near the end i
22 o# the cer? meltdown period.
'i 23 2e also looked at ancther version of this TJLE k
24 prime in which we cid not allow the containment te fail at 25 this et:1y time, and we then followed the transiant for ro e y
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- 1 time later, so there was no above-ground containment f a ilu r e.
2 in this other sequence that we looked at.
e 3
' This was particula rly usef ul :in compa ring the 4 different aerosol trancport codes, and you will sae that 5 mort of those comparisons are forothis case (indicating) 6 rather thac for this one.
'41th the early containment 7 failure, you don't get a chance to see what differencer-are 8 going to set up in the aerosol behavior of the diff erent 9 codes.
10 Gkay, than we also looked at a small pipe-break s
11 accident with,ECC failure, spray: operational; there is no 12 filter in thir particular design.
f 13 And then finally, we looked at a case of 14 small-pipe-break accident with ECC failure.with the filter-i i
15 o pe ra tin g.
And in the partiuclar desien we locked at here i
16 (indicPting), the prescura never.gets up to the point where 1
17 you would automatically trigger the spra y syste m.
Sc we.
j i
18 really have a cave here where we just icok at the filter.
I 19 (Slide.)
l 20 MR. Y0r1LE3 9an there telcw-ground f ailure 21 between the sequence where you say there is no abcve-ground 22 containment failure?
23 JR. DENN!NG:
There actually vas not.
1.nd in tha 24 only sequence where that is important is with the TM13 25 prime.
There was actually nc containment failura in that at e
r t
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Now, in most of the sequences where the pressures i
l
-3 in most cobe meltdown sequencas where the pressure is 4 re d. uc ed within the system, it doesn't really take much' 5 difference whether you melt throuch the base mat or.not 6 because you're not going to puff out into the ground.
In 7 'TMLB prime, presumably if you melted through that concrete, 8 you would have some elevated internal pressure, you...would 9 have the puff through.
We did look at that in this.
10 particular comparison.
11
"?.
ALBAUGHs Cuestion.
12 MR. DEFilINGs Yor.
13 MR. ALBAUGHs Not reing a veteran of the'TENA.
14 synd. rome, could you refrech ce or tell me how long after 15 shut down you h?ve enough fission product heat left to melt 16 tnrough the bare mat?
1 17
- 13. PENNING:
To melt throuch the base mat?
18
'3.
AL?AUGHz Yes.
Considering all the heat 19 tr*.nsfer considerations.
20
- ! R. CENNING:
I can't absolutely anrwer that for 21 you.
- t's a very open question ac to whether you would 22 res117 melt tnrouch.
Typically, there bare mats are like 12 23 feet th.cx in the United States.
24 The computer codes that are currently in existence r
[
25 tra issed upon quenching tvps cf analyees.
They cannet i
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1 really accurately = predict what happens71n the 1cnq term as 2
you.are attacking the base mat in.the long term.
So even 3 for'these cases where you have rather rapid meltdown, there 4
still is.some_questien as to.whether you would really I
5 penetrate the concrete-or not.
6 Certainly, it is less likely if you'were to delay
)
7 core meltdown for several hours than if you were to-have an 8 immediate core meltdown.
Put it really is an unanswered 9 question.
10 MR. AL3AUGHs
?cu assumed it for:ene of your cases 11 here, didn't you?
12
- y. R. CIN:::N G :
Well, sctually, we didn't assume it
^
13 in any of our cases.
It wouldn't have'tade any difference 14 to the atmospneric releases fer most of the sequences we 15 looked at..
But the specific sequence tha t ycu raise,'the 16 TMLE prime, it vould hsve made a difference if we had looked 17 at that -- not a very major difference, but it would have 18 made a difference.
let me take that back.
It would have 19 made a difference.
I can't say that it wouldn't have been a 20 major difference, because it cculd have been a significant 21 d.ifference to th e results.
22 (Clice.)
23 Cka?, then, the next is th= ice condenscr.
24 (Elide.)
1 25 And then within the ice condensor we hava two very I
ALOERSON REPORTING COMPANY, INC, 400 VIRGINIA AVE., S.W., WASHINGTON. 0.C. 20024 (202) 554 2345
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important features.- I have shown the outer bounderies of 2
the con tainment and then : ha ve also shown1 the teundary that.
3 -Separatas the upper containment volume.forethe lower 4 containment volume.
Even when you don 't have electricity, 5.you have a cora meltdown here and things have' to co through 6 the ice.
7 Ckay.
And then up above here (indicating), we 8 also have a spray system which is in'there really tc' vent 9 steam bypasces here, but it also would have scme 10 effectiveness in removing radioactive materials.
11 (Slif.e.)
12
- i e icoked at three cases here.
First of all, 13 large pipe-break accident with failure of ECC nycten, the 14 ice in place and the sprays functional.
"e locked at a case 15 with loss of 1.C powe r, b ecause the ice condenror has a 18 fairly interesting capability here of a passive 17 con d en sa tio n.
And we looked at the ice functional but with 18 no sprays because there would be ne sprays if we lost all AC 19 pcVer.
20 Incidentally, the carability of the ice to remove 21 radioactive materials hen teen evaluated experimentally by 22 Westinghouce for elemental iodine, but we didn't really have 23 anythinc here particulate iodide.
I don't know if Jim plans 24 to talk about that later.
25
- nd then there ir ancther accident secuence which ALDERSoN REPORTING COMPANY,INC.
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is a. fairly interestino one for'the ice condensor.
U 2
( Slide. )'
3 That is one.
It's-a cor. mon' mode failure.where the
~
4 accident happens, a small pipe break, cnd water gets 5 sprayed, of course, up here (indicating).
It would collect l
6 up here (in dicatin e ) and not run down to the sump.
If one 7
vere to forget to leave open some valsss that c'o down to the 8 sump from this upper deck area (indicating) and in this 9 particular accident sequence it is asaumed tha t either the 10 pathway gets blocked or people. forget to tak e those things 11 out of there, that block that flow path.
12 Eo you have a pipe-break accident, everything is 13 happeninc normally.
Ipray Water is happening up here, the 14 ice is melting, and eventually it all melts away.
They run 15 'out of water for the sprays because everything is up here 16 (indicating).
Then you go into core meltdown.
Y:u don't 17 have any ice left, and you don't have any water for sprays.
18 So that is another accident requence that we icokea at 19 there, where neither the ice ac t tne sprayr ara functional.
20 M3. ?0ELLER:
In terms of the ice condencors, we 21 noted in reading the report, and ve heard a few minutes 22 earlier this T.crninc, tha t the pctential im pact of hydrcgen 23 burn was not taken into censideration.
!!o w, ! cather that 24 van because ycu lacked the data.
Fut fo you further t
25 censide,r that its impact ic co incieni,_icant that you can ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554 2345
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1 ignore it?
2 ME. DEN 3ING:
'4 he n we said this morning that the 3 - hy' regen deflacration wasn't taken into account, we were I
4 referring specifically to the potential for conversion of',
[
5 cesium iodide to elemental iodine through oxidaticn, through 8 an event like a deflagration.
The potential for that, t
7 insofar as the potential fe: e deflagration event to lead to i
8 containment failure or to lead to an earlier containment t
9 failura, we do indeed take that into account.
10 And, in fact, in the AD case tha t I mentioned
-11 earlier -- let's see, where am I here in this case right 12 here'(indicating), the containment failure mode is really 13 the result of burning of the hydrogen in the upper-14 ' com pa rtm ent.
"o in tha t s'nse, leading to centainment 15 failure was taken into account.
18
%R. YOELLER:
Fow, will someone.tell us what.their 17 estimate is of the~ potential impact of'the hydrecen burn 18 upon the conversion of cesium' iodide into elemental?
19
%3. D EU!IN G.
That's what Dr. Malinauskse was 20 saying is a difficult problem that he doesn't feel -- didn't 21 feel could be addressed in this study, I guers.
22
!s tnat proper?
23
- 12. TIL?EE9EEG let me just note that I believe 24 Dr. Itherington 's comm ent is ctill a reasonable one, that 25 perhe.;s onn chould at least think ebout it and ess what one l
ALDERSoN REPORTING COMPANY,INC.
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mi0ht expect.
?ut
'*~o might go back and do tnat.
2
- t R. 30ELLEE:
Rich.
3 MR. SHEREY:
If the hydrogen burnLcauses' 4
containment' failure at the' time of the hydrogen burn,'then l
5 the transforma tion from one species to ancther probably-
'6 doesn't make a whole lot of difference in the atmosphere.
7 However, if it does not immediately lead to 8 containment failure, it may change the deposition mechanisms
- 9. which could affect later release.
10 MR.
0 ELLER :
Okay.
Thank you.
11 (Slide.)
12
- 3. DENNING:
2cv you will see.there ara'a couple 13 of places in here where I have specifically. put in f or Dr.
14 Catton, and this.ons is the interfacing systems LCCA 15 bypassing containment, event 7.
16 (Slide.)
17 Let me just review for you again what that is.
Cn-18 this side (indicatinc) we hava the containment.
We have-19 high-pressure systems that are connected to the icw pressure i
?
20 syst=ms throuch check valves.
If there check valves should 4
21 go fsil while you are a t crerational pressures, then you 22 could have the high pressure 1.? posed upon these low-pressure 23 systems that c?n't stand at and a failure that you would 24 then have a flow.gcing back th rough -- these are connected f
25 - to th e react:r vessel -- through there high -pressure lines l
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-into thel low-pres:ure. lines 7through the. break.into.the 2 auxiliary tuil'dinc.
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- h e auxiliary : buil' ding, this is (indicating) is.
4 equivalent to about a six-inch' break Iso it's a pretty large 5 pipe.breakD or.potentially large pipe break.. It depends upon:
6 the mode of fe.ilure overthere c.which is'very uncertain.
7' Eowever, this building does'not have a high design'-
+
8 capability, so-it'would fiil within seconds, up to a. minute.
E 9 Then ycu would have passage frtm the-fluid from-the primary-10 syctem then out to the environment..
To this is the'ficw 11 path that we're talkina-sbout.
12 It bypasces the containment mechanisms, se it was 13 a case'that we analyred.
?'ow, ve didn't analyre the primary i
14 system deposition, which!:r. Catton har mentioned before 15 could be very important here.
I think that you can infer-16-some thingc about the prinary cystem deposition one micht 17 expect here f rom the analyres f or the pipe-break' accidents.
' 18 Eut we did lock at the potentisi for depocition within this 19 volume here, once it gets released into this volume bef ore 20 it leakc out into the environmant.
21 (011de.)
22 Ckay, acxt we have the boiling' water reactors, and 23 I will q uickly run thrcuch what thcce designc icek lik=,
l 24 bacause I kncu you are familiar with them.
25 (Eli'e.)
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1 I have she wn in red the containment boundary.
i r
2 This building here (indicating) is the containment building 3 or secondary containment building.
But this is really the 4
containment envelope (indicating).
Of ccurse, the important 5 feature in all of these is the suppression pool.
6 (Flide.)
7 That was the Mark I.
A feature that I should 8 point out in the Mark I is that in WAEF-1000 the predicted 9 failure locatin for overprecsurization of the SWR Mark.!
10 containment was-in this region here (indicatinc) in the 11 suppression pool region.
If it did fail in tha t region, 12 thare =re a couple of possible flow paths for radioactive 13 materials to take on their way to this bcilding.
14 Vow, remember, there is a building around here 15 (indicating), but it has very low design pressure.
In all 16 cases, in all core meltdown cases, we predicted that the SWP 17 containment would-' fail by overpressurization eventually.
18 When it does, this building (indicating) will also fail.
19 Vow, in this particular design, there ir a standby 20 gas trea tmen t system that would cperate if this system 21 (indicating) vera intact, and they in fact have some 22 effect.
Even though it's not intact, we aid not take any 23 credit for thst, recognizing th a t there were panels in this 24 building that would ticw eut.
25
^ne release pathway is to ge into this little area I
I t
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here (indicatino) and out what we call the annulus.
There 2 is some credit taken f or deposition in this annulus, and you 3 will see we have analyzed the case in which the ficw path is 4 thic way (indicating).
S Ano ther possibility is ter this wall here, which 6 goes directly to the environmen t to f ail, in which case 7 there is a direct release pathway (indicating).
8 (Elide.)
9 3e did not a ct ila ll y do any sequences.fer the dark 10 II containment, but this is what it locks like.
Cf course, 11 tha important feature it, again, the cupprecsion pcol.
12 (Flide.)
13 And then the Mark !!!, with the supereccion pool.
14 And then there is also a r; ray system up here (indicating) 15 in the " ark !!! containment derign.
Cnce again I have shown 16 the tcundary o# thic inner re; ion, the drywell here, and 17 this outer containcent volume, wnich 1r the vaper cpace to 18 the cuppression pool c' the Ysrk TII containmant desien.
19 (Elide.)
20 The key systems again a re suppression peels and 21 sprays in ecma dericnc.
We iceked st a large-pipe-break 22 accident with failure of e er;ency core eccline system in 23 the Mark ! ', and this is a cace shere the suppreccion pool is 24 suteccled, and you wculd expect it to be vary effective in 25 :=mcVing radic=ctive materials frcr the ficw of ficsion ALDERSON AEPoRTING COMPANY. INC, 400 VIRGINIA AVE., S.W, WASHINGTON D.C. 20024 (202) 554 2345
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'le ' also lock ed at a transient with failure to I
3 scram in the Mark I.
In this case, th= pcol is boiling 4 during the core melting perled, and the particular sequence-5 we looked at here was one where-the centainment failure mode 6-war such that the flow went up through the annulus.
Wo 7 looked at a transient with failure of heat'renoval.
8 Incidentally, these twc sequences were found to be s
9 (indicating) risn-dominant' sequences for the SWP in the 10 reacter safety study.
But in this case,.We icoked at the 11 flow bypassing that annular region going directly to the 12 environment, and then we also looked at a transient with 13 1ces of all nakeup water in the Ma rk III decign, "'CUV, in 14 the cocied, subeccled.
15 Cee that we don't know, really, thic is a 16 difficult problem to handle (indicating),'the bciling pool, 17 particularly with regard to fission product removal.
You 18 will see that when we analyze this from a fission product 19 removal standpoint, we've done that parametrically.
It 20 isn't clear just how much retention there would be there.
21 You cheuld also rece;nize that in these cases, 22 containment failure can occur before er during a core melt 23 period, which introduces another question about it's net 24 just a cuestion of is the wa ter boilin g but also is it even 25 th+re?
Eecauce the containment frilure is predicted t:
r i
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1' occur within that region of the pool.
2-(Slide.)
3 And now, in,the cther -
'as've~ move on to the 4 other ahapters, people.will describe the code that we use 5 for firsion product transpert behavicr.
I wanted to mantion 6 here the methods that are used for the thermohydraulic 7 analyses, because, as Dr. Catton has pointed o u t', there are 8 some significant uncertainties in thermohydraulics.
Ther 9 csn have a major'effect on fission product transport 10 behavicr'.
11
'f o w, throughcut here, we have used the Yarch 12 computer code to analyze the th erschyd raulic behavior.
As far as the thtrmohydraulic conditions within the. primary 13
\\
14. system, the March code doec not predict those.
It predicts 15 gross behavior of the primary system, but it doesn't show, 16 as you go from the upper plenum to the hot leg to the steam 17 generator, what tne steam temperatures and conditions e re as 18 you move through the primary system.
There is ne code 19 currently available that does that during this period.
20 So we did some hand calculations to supplement the 21 March computer cof.e, and they a re subject to la rga 22 uncertainties.
They can have a significant effect on the 23 amount of ieposition that One predicts within the p rima ry.
24 There is some sensitivity snalyses to try to give you a 25 handle as to how big that effect micht be.
There is a
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definite weakness or inability to analyze these things.
2 Also, you should recognize that with regard to-p 3 containment, that the-timing,and mode of containment fajiure 4 have a particular effect-on the consequences of an 5 accident.
If the containment remains intact or it' remains
,6 intact for a specific period of tire, you're going to have a 7
pretty minor accident in comparison-. te the - alterna tive.
IN 8 you have an early atmospheric failure of the containment, 9 that'c the kind.of condition in which you have the very 10 1srce release fraction and which you will see as a result cf 11 some of these accident sequences.
12 So, in conclusion, ! wnat tc say that there are 13 uncertainties in the thermchydraulice -as well as in the 14 models for predicting fission product transfer.
And these 15 uncertainties affect one's ability to predict fisrion 16 product behavicr.
17 Tha t concludes m t ;resentation.
,F.
CATTCNs What would you say is the biccest 18 19 uncertainty?
"nowledge of the scurce strength or the 20 transport mechanism ?
21 Z F. O E} 'i!!!G I am not sure what you meent by the 22
" source strength."
23
?R. C ATTC:':
The fission prelucts that you are 24 moving from one place to.another, I sort of have a 25 sim plistic vi,-v of ccurce transport environment.
Transport ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, o.C. 20024 (202) 554 2345
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2 is the weakest link.
3
.13. DENNING:
It.isinot in the source with ragards 4
to particularly what one looks at iodine and cesium.
For 5 core teltdown sequence, there is quite a bit of a'ssurance
~ to be. released 6
tha t a very large fraction of.that is going 7 from the fuel.
Okay?
So then you.have uncertainties as far 8
as, the deposition in the-primary system, uncertainty with 9 regard to ieposition in the containment for thines like T?.LB 10- prime, I think the biggest uncertainty is will you have a 11 containment failure that cccurs right'after core meltdcwn?
12 3?. CATTON:
But really, without a' code to handle 13 the primary system, without a means of calculating the.
14 behavice in the centainment.very well, we really don't 15 cant do an ything but bound.
~16 MR. DENNINGs No, I definitely wouldn't say that.
17 You will see the results of unc e r tain ty studies that have 18 been done here which I think pretty well show us what the 19 spread of possible consequences are.
We've done an 20 uncertainty analysis, for axample, on TMIS prime with 21 MA?CH-CORRAL.
And we have also done an uncertainty analysis 22 with the !? A? code.
23 Now : think you can cet a pretty good ides there 24 of what the possible ranges a ra with realistic assumptions 25 about how ' rod ly these conditic ns migh t va ry.
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-1 range is f airly broad. -So thr:re is a lot of room'for
-l 2
improvement or for error.
3 vF. CATTON4 I thought that's what I' implied.
4 X3. :EITNING 4 Okay, well', I think what you had 5 said was all you could do is bound.
And I thought you were 6
implying upper bound.
'a'h e r e a s, if you 're saying a range of 7 uncertaintias, I agree with you.
8
- 23. 20EllE3:
Any othar questions for'"r. ";a nnin g ? '
9 MR. ETHERINGTON:
I 'ound the drawings that you 10 showed on the screen of the PWF much better than they are 11 shown in the report.
Why io you use chese?
12 vE. SEN:i!N G:
That is an excellent question.
I 13 think that the drawings could definitely be improved, and 14.maybe we can srend some investment into that.
15 MR. ETHERINGTON:
Yas, you could clean them up.
16
R. DENNING:
Yer.
Actually, the drawings that 17 would actually be in the real report, those were, of ccurse, 18 Xeroxes of figures.
The figures would come out mere 19 clearly.
However, you can't see the type of things that I 20 tried to snow here.
21 MR. ITHE?INGTON:
Yos, that's what I meant.
22
- ne other questien.
Have you tried to assign any 23 probabilities to your various requences?
24
R. CEN:iING:
Wall, it wasn't our intent to do 25 that for this ctudy.
That is very plant-desien-specific, as ALDERSoN REPORTING COMPANY,INC,
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1 you can imagine.
2-
- 23. ETHEPINGTON:
When you talk of' risk, you.have
.3 tc.de something 4
MR.. DENNING:
We'did try to include what we i
5 thoucht were risk-dominan t sequences, prima rily using cur 6 judgment base: upon the reactor' safety study and *he Feactor 7 Safety Study '.'ethodology Applications Program., which is a 8 ' study that is just. nearini completion, a joint 9 3atte11e-Sandir study.
10 However, I think tha t you have to reccenize that 11 that dces depend vety much on -the particular plant design.
12 hE. ETHERINGTON:
- le l l,- a t least, if somebody i
13 sutsequently decides to assign probabilities, then they 14 can 't use this report to establish relative risk.
15
E. DENNI!G:
I think they can us'e it to help 16 predict what the release magni.udes are, yes.
17 MR. "CELLEP:
Any other questions for Mr.
18 Denning?
19
( l'o respo nse. )
r 20 3R. %CEllE3:
T!.ank you very much.
Ihat was,well 21 done.
We will move on to the next presentation, which is 22 fission products releases fren the fuel, and this will be by 23 the Cak Ridce grou; and Mr. 'a'ic h n e r.
24 (Slide.)
.25 JF. 4!CHUER:- Just to intreduce the authers, ! am i
1
)
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Bob 'Aichner, from FC1.
2 MR. FOELLE34 We are going te have' trouble hearing 3 you, Bob.
4 (laughter.)
f 5
3R. WICHNEP This talk is divided.
In the first 6 half, I will be giving the'first half, and Tom Xress.will be 7 providing the second half of the talk.
And Oick'Lorenz is 8 another significant chapter.auther who is not here.
And I~
9 mi7ht mention that we did have contributions from Argonne 10 and AOCG, which are present in the report.
11 (Slide.)
12 The objective of Chapter 4 in the overall scheme 13 of things is given in this slide.
P rincipa lly, what we 14 would like to do'is to look at the evidence and cee if we 15 can determina the chemical form of iodine in the fuel Or 16 evolved from the fuel; secondly, determine what the rate of 17 evolution is --'and here we ara a little bit more general.
18 The rate of evolution of fission products from overheated 19 fuel in comewhat of a cide iscue.
We were arked to lock at 20 the effect of interacting the cladding with the UC2 as it 21 might ?.ffect the rete of release f rom the f uel.
And 22. finally, to put this together with an accident sequence to 1
23 determina the whola core relaase.
24 This item 3 will be handled as the second part of 25 the tal?. by Tem Kresc.
I vill be addressinc principally I
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3 I will b:iefly co into wherecthe-fissicn productb how they arrive in the fuel, very briefly.
!,will-Ljust 4
5 briefly indica te what is indicated on this slide, withcut 6 ' going into-too much detail.
For example, the first column 7 indicties the
.T. ass number ; the second column' indica tes the 8 amount of atecs per hundred fissions that arrivad that.are 9 borne, had that mars number.
For this case, they will be 10 2.93 for mass number 131.
11 The tracket indicates the element at birth.
In 12 this cese, for-the example, antimonium and tellurium are the-13 birth slements in mars 121.and subsequently with date cf 14 dec2y, it ;oes to your righ t.
15 So the point I would like to make with this slide 16 -- wnich'you can study perhaps later -- is that indeed 17 tallurium is a significant precursor for all iodine as we..A 18 as all xenon species.
19 The recond -- in addition to simply being a 20 precursor and possibly affectino the subsequent location of 21 tne icdine as it is borne, it is also present as a stable 22 species, to that even beycnd that, if th e re ir a chemical 23 affect of tellurium, there is sufficient amounts of 24 telluriun to affect the subsequent beha vier.
Mcwever, this 25 is an unkn wn *,res, 2nd ne positiva statemente could be made i
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about it.
2 The second thing I would like to peint out is'that 3. the amount of cesium produced is significantly granter not 4
just solely by radioactivity, but by. mass.
The amount-of 5 cesium being genereted by fission directly indicates stable 6 ~ cesium species are almost stable cesium species.
Ycu get-7 cesium as well by building it in f rom a xenon by neutron 8 activation.
9 So the amcunt you can take xenon-133 and it could 10 abscrb neutron, enit a tens, and cesium-134 and these cesium 11 species add sionificantly to the amount of cesium you 12 generate directly by fission.
So when you add it all up,
13 roughly you have about 10 times as much cesium as iodine on 14 all the-bases.
15
.'! E. "CEllEns A couple of questions.
16 Go shead, Dr. Lcwreski.
17
- 13. L A'4 E CE X : s I juct want to make sure I 18 understand your second column.
The to tal of that recend 19 colurn would he 200 percent; is that correct?
20 ME.
'4 !C H.N E E :
Yor.
21
E.
0 E11E E :
I was intrigued when : read the 9
22 ori71:ml re pcrt, which this ir taken from.
I-129 has a 23 half-life of about what, 10 million years?
And ycu say 24 th1t's approximately inifinity?
' 25
- 23. ;ICETEE:
Yac.
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MR. "0ELLES:
Is that an Oak Ridge's judgment?
2 (Laughter.)
3 MR. WICHlEE:
I d idn' t mean anything 4 sophisticated.
If you're adding up nasses or molar amo unts, 5 you would for that purpose lump 129 with the thing that 6 stays arcund fcr very long periods of time.
I didn't mean 7 that to imply any radicactive hazard f rom tha t.
8
- R. i:0ELLEE s Okay, that's adequate.
I think you 9 ought to give a footnote or scrething and explain what you 10 meant.
11 Down there, with the two reactions that are 12 producine the cesium-134 and -136, again the way you have 13 written these icu imply it's cn end beta reaction.
14 I am getting inte details, but what you sctually 15 do, isn't it in 133 to go to 134 yenon, which decays by 16 beta?
17 YE. '!!C H N E E.
Yes.
Fi;ht.
18'
E. "CILLE?:
MCst rn d rea ctions are in gammes and 19 probably it it an end gamma roaction that driver the 133 to 20 134 21
'i 3. NI C 2 N' E 3 :
Eicht.
Your oint is well taken.
22 This tornino10cy i.e not ecrrect ac to what ha;rens.
23 LE..:071;EEs Ckty.
Thank yeu.
24 "O 3 head.
25
.E.
I A%? C27.I t Usin~ tco much shorthand there.
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'M R. WICHNER:
Yes.
2 MR.,KABAT I am sorry, may we see that table 3 again?
4 (Slide.)
5 MR. KABAT:
The yield.of iodine-121 from decay of 6 thorium-131, which has only 25 minutes' half-life, it means 7 that the number, if they are in equilibrium in the f uel, in 8
the decay equilibrium, it means that there would be about at 9 least 100 times lover amount of tellurium atoms.
It means 10 from the accident that would be only one-hundredth of 11 tho rium atoms countering this iodine-131; so it means that a 12 subsequent production of iodine-131 from thorium would be 13 relatively insignificant.
MR. WICHNER:
Yes.
14 MR. KABAT:
That would add only less than 1 15 percent off the iodine-131 from thorium decay.
And that was 16 actually a subject we discussed on a few occasions here, how 17 much iodine would be actually produced from tellurium 18 released from the fuel during the accident itself.
So I 19 think it wouldn't truly be so significant.
' 20 MR. SHERRYs In fact, that exactly is addressed in 21 Chapter u.
22 MR. KABAT The 132, 133, and 134 a re short-lived 23 lodines and would be produced in larger quantities, but it 24 is relatively shortlived isotepe which wouldn't produce any 25 environmental hazard.
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'MR. MOELLER:
Did you get the answer you needed?
2 MR. KABATs
-I would say it was rather a comment 3 than an explanation.-
4 MR. M0ELLERs Okay.
5 (Slide.)
6 MR. WICHNER:
Let me point out some basic. physical 7 properties of some of the materials that we're dealing 8 with.
Let me emphasize that the melting point and the 9 boiling point columns.
Cesium, it is thought, would exist 10 primarly as a' cesium uranate and the melting-point at 940 11 degrees,'which like cesium iodide indicates that some of the 12 inner portions.of the fuel will be molten and it would-be 13 solid at the outer por tions of the fuel.
And in fact, also i
14 that cesium ure.nate is not one of those compounds that has a 15 distihet boiling point.
16 What you do is you drive off the cesium from the 17 uranate and simply increase the vnpor pressure of cesium 18 above the uranate so you don't have a clear boiling point, 19 whereas the elements are much more volatile with the icwer 20 melting points for the elements and also lower boiling 21 points for the elements.
22 So we're dealing with materials that could exist 23 either as a crystalline solid or as a liquid on the 24 interior.
25 MR. ETHERINGTON:
Does the formation of cesium ALDERSoN REPORTING COMPANY,if40, 400 VIRGINIA /.VE., S.W., WASHINGTON, D.C. 20024 (202) 554-2345
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uranate imply oxidation of some of UO2 and the reduction of 2 another part of the UO2?
Where does the extra oxygen come
-3 from?
4 MR. WICHNER:
It combines with UO2, cesium 5 combining with UO2.
6 MR. ETHERINGTON:
Yes, but then tha t wouldn 't give 7 you the CS2, that would just give you UO2 unless you pick up 8 the oxygen f rom somewhere ele e.
9 MR. WICHNER:
Cesium urana te would tend to forni 10 with a sligh c excess of oxygen.
You don't normally have 11 UO2.
You have UO2 with a slight excess of oxygen.
12 MR. ETHERINGTON:
I see.
There is sufficient 13 excess to give you that?
14 MR. WICHNER:
Right.
So the slight excess would 15 tend to --
16 MR. ETHERINGTON:
Is this known to exist or just 17 believed?
18 MR. WICHNER:
Tha t's a good question.
I am 19 assured that it exists.
However, it has not been observed, 20 and I will get to that point.
21 MR. ETHERINGTON:
In general, with all of the 22 fission products coming out as elements and many of them, f
25 like calcium and strontium, the tendency would be to reduce j
24 UO2 rather than to provide the extra oxygen.
25 MR. WICHNER:
Well, the point you raise about ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W,, WASHINGTON D.C. 20024 (202, 554 2345
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whether this actually exists, I am not certain it has ever 2 been observed.
However, thermodynamica11y, it is strongly
/
3 implied.
4 MR. KABATs
'Jould this excess of oxygen be 5 available for reaction with some of the fission products?
6 MR. WICHNER:
The proper way to phrase the 7 question is that the fuel has a certain oxygen pressure 8 associated with it which depends upon the amount of oxygen 9 in excess of the stochiometrically required amount.
And 10 that oxygen pressure has an effect on stochastically 11 required amount.
And that oxygen pressure has an effect on 12 a large number of possible reactions.
13 (Slide.)
14 Now, as far as identifying the iodine chemical 15 form, there are a number of approaches that you would want 16 to take or that you could take.
17 You could observe the phase compositi n directly, as has been done by Clay Camp and TFK; or one can look at 19 concentration profiles from discharged fuel and try to infer 20 f rom the manner in which the profiles match what sort of 21 chemical species you have.
22 MR. MOELLER:
Dr. Steindler ha s a question.
23 MR. STEINDLEBa Before you go too far, I assume 24 you are going to eventually get to your thermodynamic 25 calculations.
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'MR. WICHNER:
Yes.
2 MR. STEINDLER:
My. question iss Did you use that 3 value of minus 1511 kilojoueles per mole for the pre-energy 4 formation of cesium uranate?
l 5
MR. WICHNER:
No, I just put that column in as 6 sort of --
7 HR. STEINDLER:
Where did that value come from?
8 MR. WICHNERs It came f rom a paper by Besman and I
t 9 Lindemer on this subject.
10 MR. STEINDLERs Would you estimate that it is 11 reliable?
l 12 MR. WICHNER:
Yes.
That is not an unusual f
13 compound.
That should have a reliable value for the free 14 energy f orma tions.
i 15 MR. STEINDLER:
It seems awfully high for material i
16 tha t you can 't find in the solid pha se.
In fact, you can't i
17 find it.
4
(
18 HR. WICHNER:
Yes.
It could be dispersed.
That 19 could possibly be a reason it's not found.
20 MR. BELL Excuse me, Bob.
21 Bell, from Cak Ridge.
22 When you say it's not found, you mean that it's 23 not been observed experimentally, or it's not been observed 24 in the fuel?
25 MR. WICHNER Not been observed in discharged j'
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fuel.
2 MR. BELL 4 But in controlled experiments, it can 3 be made?
4 MR. WICHNER Yes.
And the high value is a bit 5 misleading.
It has something to do with the number of atoms 8 per molecule as well.
7 HR. STEINDLER:
Well, even if you divided by two 8 and you normalize everything to per mole of cesium, it is 9 still pretty high.
10 MR. WICHNER:
Well, the general implication of 11 that large negative value is that it is the preeminent 12 stable specie of cesium in UO2.
13 ER. STEINDLERs That is exactly my problem.
I 14 don 't think it is a preeminent stable specie of cesium.
15 There is a cesium-U4 compound that apparently is more 16 stable, and tha t 's why I am trying to focus in on why you 17 are addressing that particular species.
18 MR. WICHNER:
I believe on'that point there is a 19 disagreement between that and the thermodynamic studies that 20 I have used to f orm the -- that part of this chapter.
21 MR. STEINDLER:
My real question is how important 22 is that disagreement to your conclusions?
23 MR.'WICHNER:
It may be significant, because, 24 Well, for one thing, I don't put a great deal of weight on 25 the thermodynamic results.
I present them, but I feel that ALDERSoN REPORTING COMPANY,INC, 4t10 VIRQiNIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554 2346
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perhaps one ought to qualify those results.
I present 2 them.
3 However, if one were to use the thermCdynamic 4 results with a great deal of force, then I would believe 5 that that would -- that tla t comment of yours would be 6 significant, because the thermodynamic calculations presume 7 that the environment that the iodine sees in the fuel is one 8 in which the partial pressure of cesium is basically the 9 partial pressure over cesium uranate.
So it would have a 10 big effect in that case.
11 MR. SI1BERBERG:
You mean effect on release 12 fraction of cesium?
13 M R. WICHNER:
No.
Effect on the chemical form of 14 lodine as calculated by chemical thermodynamics.
15 MR. SIlBERBEFG.
I see.
Thank you.
16 MR. KABAT4 Have you calculated the free path of 17 the iodine in cesium atoms in the uranium nitrates which 18 would, of course, be quite limited and that might eventually 19 affect the reaction rate or the equilibrium?
If the free 20 path is long enough, it might still be diffusion-controlled 21 reaction but it would surely affect kinetics of reaction 22 between cesium and iodine?
23 MB. WICHNERs I have a very limited knowledge in 24 that area.
By impression is, however, that at temperatures 25 below 1400 these large atoms are essentially immobile --
)
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MR. KABATs Yes, that's what I mean.
2 MR. WICHNEBs
-- in the matrix.
And it would be.
3 extremely difficult to predict the f requency of collisions 4 between these atoms to allow some generalization on the 5 subsequent chemical form.
And this is, in-particular, my 8 reason for not overly emphasizing the chemical-thermodynamic results, one of the reasons.
8 MR. KABATs Yes.
9 MR. WICHNERs However, I do present them.
10 (Slide.)
11 The conclusions regarding -- these are actually 12 partial conclusions.
13 First, there are no iodine-bearing phase has been 14 identified in the fuel.
But of the 20-odd phases that have 15 been observed by Clay Camp at KFK, he has observed none
~
16 containing iodine.
I think what that means, is that either 17 iodine is not -- is either in a separate phase finally 18 dispersed or in the UO2 grain.
So the direct observation 19 does not lead to a clear result of specifying the chemical 20 form of serving concentration.
21 Yes, sir?
22 MR. STEINDLEBs I think that's a fairly critical 23 conclusion.
24 MR. WICHNER4 Yes.
j 25 MR. STEINDLER:
I am wondering why you decide that 1
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1 because you haven't been able to see cesium iodide in 2 sufficient size aglomerates, that you can identify cesium 3 iodide crystal that you worry about whether iodine is there 4 as a cesium iodide.
5 ER. WICHNERa Well, let me put it the other'way.
6 What I an doing is looking at what evidence is there to 7 det' ermine whether or not one can come to a conclusion from 8 that evidence.
9 Now, the evidence is a description of phases that 10 have been identified, and none of thsoe phases have been 11 listed as containing iodine.
Now, that is the fact in the 12 literature.
Now, what conclusion one forms from that, that 13 is just my impression.
14 MR. STEIND1 era I am not in a position to quarrel 15 with your facts, I think.
But I am wondering how you got to 16 the conclusion.
17 MR. WICHNER Well, the conclusion is really my 18 opinion.
19 MR. STEIND1 era I see.
Okay.
You will perhaps 20 admit that there is a possibility of cesium iodide beino 21 there in such a phase that you can 't see it as a crystalline 22 material?
23 ER. WICHNEBa Yes, certainly.
Sure.
- However, 24 cesium, the second half of the item 1,
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researchers, in one case by Cooper Jahdi, working for'EPRI.
2 And usually, these are observed on f ue'l pins that have 3 higher pins, higher heat rate in them than. usual, and these 4 crystals have been observed.
5 The second item, I found nothing really
.I 6 distinctive in concentration profiles to give any clear
~7 evidence as to what the chemical specie is.
This vas sort 8 of a long shot.
Sometimes you.can see a unique feature in a 9 concentration profile to allow identification of-a chemical to specie, but that does not occur in this case, as far as I 11 can tell.
12 Third, there are a number of thermomigration 13 experiments that have reported.
These are experiments where 14 you have powder and temperature gradient, and you add cesium 15 and iodine in various forms, and you see where it comes down 16 in the temperature gradient.
There have been experiments by 17 Pea se and Wiedenbaum, and they disagree as to whether or not 18 cesium' iodide form.
Wiedenbaum says yes, Pease says no.
19 However, they do agree that when you add a small 20 amount of oxygen to the system, that you tend to form 21 whatever you had bef ore you tend to f orm a molecular iodine 22 subsequently.
23 Now, all I am going to say about chem-thermo is 24 listed in item 4 Within the limitations of the study that 25 was made by Besman and Lindner, their conclusions are that ALDER $oN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554 2345
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the stable forms and the f uel a re cesium iodide, cesium 2 uranate up to 950 centigrade, which is the limit of their 3
study.
They found that adding steam to this system did not 4 change things too much.
However, oxygen, they found, did 5 destabilize. cesium iodide.
Basically, what it did was lock 6 up cesium in a more stable uranate, making it unavailable 7 for cesium iodide.
8 MB. STEINDLEE4 Are you suggesting by that 9 conclusion that cesium is present in really only two kinds 10 of material; namely, cesium iodide and cesium uranate?
11 HR. WICHNERs I think the more caref ul statement 1
12 would b'e to say within the realm of chemical-thermodynamics 13 and within the temperature range of this study, yes.
14 However, the realm of chemical-thermodynamics is a 15 limited realm.
Sometimes there are rules that you have to 16 use in chem-thermo tha t don 't really apply to your situation 17 that you have.
And this is the reason why I am not i
18 overemphasizing thermodynamics in this regard.
19 MR. STEINDLER:
Well, can I drive you out away 20 from that nice, neat limitation?
21 MB. WICHNER:
Yes.
22 ER. STEINDLER:
If you would just address the fuel 23 in general and not the study and what you know of the rest 24 cf the literature, would you still say that cesium is only 25 found in two compounds ?
If I pulled fuel out of the reactor ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W WASHINGTON, D.C. 20024 (202) 554 2345
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and let it cool for a few days at rocm temperature and gave 2 it to you and you looked at it, where would you expect.to 3 find cesium?
4 MR. WICHNER In some cases, you would find cesium 5 that has migrated down to cooler portions and exists there 6 a s metallic cesium.
In some cases you would find cesium, 7 some cesium, in around the gap between the pellet and the 8 clad.
9 MR. STEINDLER:
As metallic cesium?
10 MR. WICHNER:
As a form that during operation was 11 in the gas phase.
I mean vague.
And occasionally you would 12 find cesium as a compound with zirconium on the surface of 13 the pellet.
But this has been observed only in extremely
(
1-4 high-heat-rated fuel, Similarly, you would find come 15 cesium-bearing compounds on the cladding and cesium iodide 16 has been found on the cladding.
Again, I believe, only for 17 heat ratings above the design heat ratings.
18 MR. STEINDLER:
The rationale for the question, 19 obviously, is I am looking to see what information you have 20 been able to accumulate on were cesium to get tied up in 21 compounds more stable than cesium iodide --
22 MR. WICHNER:
That point is a very good point.
23 And I did look, and I don 't believe there is much background 24 to allow an answer to that question.
It is a complicated 25 question, because of the very difficult mobility of these ALDERSON REPORTING CoMrANY,INC, 400 VIRGINIA AVE., S.W WASHINGTON D.C. 20024 (202) 554 2345
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heavy atoms in UO2 and what opportunities they have for 2
chemical combination.
I don't believe that question can be 3 answered.
4 MR. STEINDLER:
One comment, or two comments.
The 5 cesium uranate that you're looking at is -- the one tha t 's 6 on the slide -- is probably not the most stable form of the 7 cesium-uranium-oxygen system.
Two, there has been no 8 comment made I was a little bit surprised tha t there has 9 been no comment made on cesium melecta tes, which vaporize 10 congruently and represent part of the vapor transport at 11 high temperature.
Congruent vaporization is not a good 12 enough reason to call something stable, but at least it adds 13 the question as to whether or not a cesium malibdate may be 14 another sink for cesium that wo uld take it out of the cesium 15 iodide domain.
16 MB. WICHNER Cesium malibdates were examined by 17 the study by Besser and Lindner and they determined that 18 cesium uranate was more stable than a malibdate.
Again, I 19 have to qualify, for a given oxygen pressure, their 20 conclusien is that cesium uranate is the most stable species 21 for this oxygen pressure that is sppropriate for a U02 with 22 a slicht excess of oxygen.
23 Now, it's true that other cesium uranates become 24 more stable, but at higher oxygen pressures.
25 M R. KAB AT:
Have you included the effect cf l
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96-1 hydrogen high energy of different kind of radiation on 2 actually th e thermochemical analysis ?
3 MP. WICHNERs No.
That is another point, another 4 reason why I do not like to emphasizs the chemical 5 thermodynamics.
This point cannot be accounted for in 6 chemical thermodynamics.
7 MR. KABAT:
Would you expect that it could have a 8 very significant effect?
9 MB. WICHNER:
It's only my suspicion, but I think 10 metal halides can be affected by intense radiation.
So it 11 could shift some of the equilibrium.
12 Maybe some of the more chemically oriented people 13 could comment on that.
14 Well, I don't know.
I don't want to put anybody 15 on the spot.
18 MR. BELL:
I would expect the gradient ra dia tion --
17 MB. LAWROSKI.
We can 't hear you, sir.
18 MR. BELL:
I would expect the greatest radiation 19 damage in the fuel would be on some oxygen-containing 20 species crea ting an oxygen radical type reaction, 21 essentially the redox contention.
22 MR. LAWROSKI:
It is what?
23 FR. KABAT:
Significantly affect the chemistry of 24 iodine and cesium inside the fuel.
25 (Slide.)
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97-1 MR. WICHNER:
I will have to go a bit into release 2
rate mechanisms, and this is a very touchy point, as some of
(
3 your questions have already indicated.. And'it ' is also a 4 matter of some opinion, one investigator to the next.
This 5 opinion presented here is predominantly.the one presented by 6 Lorenz.
I have to go through this a bit to be able to 7 understand some of the variations in the da ta that are going 8
to be observed.
9 Initially, what you have, you have the cladding 10 burst and you have a release of gaseous materials from open 11 voids in the plenum.
Confounded with that release is a 12 release of some embedded noble gas which -- well, again, I 13 am presenting a model as developed by Lorenz -- in a 14 temperature range approximately that..
Then you would get.
15 cladding burst.
16 You can also release noble cases that are 17 shallowly embedded on various surfaces.
And it's a subtle 18 difference, but some experiments might have different 19 amounts of this release relative to the others, and it does 20 cause a bit of confusion occasionally in looking it some of 21 the release data.
22 Following cladding failure and release of'the 23 shallowly embedded noble gas, you then have a process of 24 diffusion to the failure point at about 1400 centigrade.
25 You have something called " grain boundary release" beginning
)
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1 to occur, which involve several processes and seems to occur 2 about 1350 to 1400. centigrade.
3 And the processes in volve bubble, linkage, grain
~
4 boundary growth and separation, all of which you tend to 5 have sort of a rapid evolution at this point, and high 6 burn-up fuel.
I don 't know what it would be in low burn-up 7 fuel.
It might occur at a different temperature.
8 And then, subsequently, you can diffuse material 9 actually from the grain interior to the grain surface.
10 Actually, diffusion occurs altering this process.
- However, 11 it would become the dominant method of, release only at 12 higher temperatures.
13 (Slide.)
14 So you have these release mechsnisms.
15 BR. ETHERINGTCNs Let me ask a question to clear 16 up something for me, please.
In a solid lattice-like 002, 17 where both cesium and iodine, does it know that it's cesium 18 iodide to the extent that it becomes a separate phase?
19 ER. WICHNER:
I don't think that question can be 20 answered.
There are several things that possibly could i
21 happen, and I don't know if anyone can say definitely that 22 one thing happens.
You have a general notion of noble i
23 gases.
24 MR. ETHERINGTON:
Yes.
25 5R. WICHNER:
It could be towards the grain ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 !202) 554 2345
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1 boundary.
2 MR. ETHERINGTON:
When it migrates to the grain 3 boundary, you have a void in which a compound can form.
4 3R. WICHNER:
Yes.
5 MR. ETHERINGTON:
But within the lattice, would 6 there be anything to say what it is?
7 MR. WICHNERs No.
I 8
MR. ETHERINGTON:
All right.
Thank you.
9 MR. WICHNER One can look at 10 MR. EELLs Excuse me.
11 3R. WICHNER:
I am looking -- Yes, sir?
12 MR. BELL:
Excuse me, sir?
13 MR. MOELLER:
Harold, they have further 14 comments.
15 MR. ETHERINGTON4 Excuse me.
i 16 MR. BELL With respect to your question of 17 species in the lattice, I don't think you'd expect micration-18 of anything other than atoms --
19 MR. ETHERINGTON That's right.
20 MR. BELL
-- inside the atom.
21 MR. ETHERINGTON:
That was my thought.
But when 22 you get to the grain boundaries, you 'd have a dif ferent 23 condition.
24 MR. EELL:
Yes, you could.
25 MR. WICHNER:
That's an extremely important point, ALDER $oN REPORTING COMPANY,INC, 400 VIR3 INIA AVE., S.W., WASHINGTON. 0.C. 20024 (202) 564 2345
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because'a significant fraction in the. life of any fission i
2 product exists in that form as atoms migrating in.
UO2 and 3 how they migrate, what opportunity they have for chemical 4 combination within that grain is, I believe, not answerable-5 at this point.
6 MR. ETH ERING TON :
The metallurgists have empirical 7 rules.
I think i t 's somebody -- Rotheti, i sn ' t it -- rules 8 of potential solubility based on atomic size, atomic radius 9 and valents and a few other things?
Is there any similar 10 theory in a compound like UO27 11 MR..WICHNER:
That takes me out of my area of 12 s pe cia lty.
13 MR. ETHERINGTON:
Humeri is the name, or something 14 lik e tha t.
15 MR. WICHNER:
It was the same purpose of 16 identifying the iodine species.
One can look at release 17 rates.
In particular,.one notes that iodine and nchie cases 18 come off uniformly at equal rates.
Well, that is a strong 19 indication that you have a highly volatile f orm of iodine in 20 the fuel.
On the other hand, if iodine and noble gases come 21 off at significantly lower rates, that would be an 22 indication that the iodine is locked into some more stable 23 species than molecular iodine.
24 So, with that point in mind, I have to note that 25 the early data, in basically Pa rker and Davies, actually ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE S.W., WASHINGTON. D.C. 20024 (202) 554 2345
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1 indicate a more rapid evolution of iodine in noble gases.
2 And this -bias is still built in the ANS 5.4 code, which is a 3 little bit surprising to recommend for the release rate 4 correlation.
They recommend diffusion coefficient for 5 iodine seven times that of xenon, and it's' based on these 6 early observations of Parker and Davies.
7 Again, let me speculate why is this so.
I think 8 the reason it is so is that both Parker and Davies did not 9 use fuel elements and their experiments did not fully 10 account for all the release mechanisms that are possible.
11 And I think that they actually did not see some of the noble 12 gases that they had lost prior to the experiment, because 13 they didn't contain it with cladding and they lost the 14 shallowly embedded noble gases.
15 That is my speculation.
But that is still present 16 in existing technique, that bias.
17 "E.
LAWROSKI But they should ha ve been observed 18 differently, depending on the sire of the chunks of fuel 19 they were working with.
20 MR. '4!CHN EB :
They didn't do that many 21 e xp e rim e nts.
And Davies did observe such, because he used 22 pellets and powders, both.
23 MR. *0ELLER:
Dr. Steindler.
24 MR. STEINDLEE Are you saying th a t the Parker and 25 Davies' experiments are not well enough written up to be ALDERSoN REPORTING COMPANY,INC, l
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able to evaluate the validity of the speculation that you 2 came through with?
3 MR. WICHNER:
They make no such specula tion.
I 4 emphasize that is my speculation.
And I don't want to say 5 that.
6 MR. MOELLER:
Repeat your question.
7 MR. STEINDLER:
My question is:
Do you believe 8 that the papers written by Parker and Davies contain 9 insuf ficient information to either validate or comment on 10 the importance of that spec ula tion ?
11 MR. WICHNER:
I wouldn't put it that way.
Parker 12 and Davies both present their observations, and now you are 13 free to analyze them and interpret them.
14 MR. STEINDLER:
Let me try it once more.
A lot of 15 people write a lot of papers in which they present 16 information, but the question usually is:
Is it presented 17 well enough to be either complete, or traceable, so you_can 18 identify fairly clearly the answer to the questions that you 19 ask ten years later.
There is an awful lot of junk in the 20 literature, sir.
21 (Laughter.)
22 MR. WICHNER:
Yes.
Yes, indeed.
23 MR. STEINDLER:
That may be part of it.
I guess 24 what I am really getting after is:
In the work that was d
25 behind putting this volume together, was there any l
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1 significant attempt to critically evaluate the quality of 2 the information that you.have been able to dig out of the 3 literature?
4 MR. WICHNER:
I am actually going to come to that 5 point in a moment.
But the short answer iss not 6 com pl etely.
The full evaluation of each experiment could 7 not be done in the scope of time.
But if I can get a plug 8 in for another NRC-f unded program that is a milestone in the 9 severe accident sequences analysis program for later in the 10 year.
11 MR. MOELLER:
Don Orth has a comment.
12 MR. ORTHs Yes.
I don't remember that particular 13 paper right now.
But I have gone through evaluating some of 14 the papers.
One of the key points when you are trying to 15 support the speculation you get is not just the rates which 16 came out but the total amounts.
And in some cases, you find 17 the rates indeed say this sort of thing, but they can't 18 account for about 90 percent of the material that was really 19 supposed to be there.
So --
20 MR. WICHNERs I agree.
I don't know about Davies, 21 but I agree that the mass balances on Parker 's experiments 22 did not work out very well.
That much I know.
23 Well, later experiments by lorenz -- and here I 24 vish -- I misvrote this -- I wish you would correct this on 25 your copy.
I don't mean " grain boundary release."
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" embedded gas release.'"
So please cross this out.
I just 2
wrote the wrong words down.
l 3
Cross out " grain boundary" and write " embedded gas j
4 release."
That's mechanism 2 rather than 3 or u.
I just 5 wrote it down incorrectly.
8 Later experiments by Lorenz don't bear this bias 7 of more rapid iodine release relative to xenon release.
8 However, the situation is not clear, because you have 9 several mechanisms being involved, and all you can say is 10 that you get approximately the same amount of iodine and 11 xenon released at low temperatures as far as Lorenz' 12 experiments gc 13 At higher temperatures, at 1400 and above, or at 14 about 1u00, Lorenz' experiments show equal parts of iodine, 15 cesium, and noble gas release.
16 The other thing I would like to get into relates 17 to a feature of Lorenz' experiments where he had something 18 actually identifying the species.
Up till now we've been 19 looking at seeing if we can infer something frca a 20 relative release rate.
But there is a species 21 identification attached to Lorenz' experiments.
And that is 22 on the next slide.
23 (Slide.)
24
,A couple of significant points here.
Lorenz had several thpes of experimentr, and 25 I ha ve abstra cted these ALDERSoN REPORTING COMPANY,INC.
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results from Table 4.3, which is in the report, and I really 2 urge you to look at the f ull report, because there is not 3 any fully adequate way. of abstracting it.
I have tried just 4 to get it on the slide.
5 What I mean to show here is that in his 6 experiments, where he employs helium to carry off the 7 evolved noble gases, he -- oh, the three species that he can 8 crudely identify -- and maybe " crude" is not the proper word 9 -- but in its analytical train he has, he can observe a 10 location of a deposit and infer that that deposit is cesium 11 iodide or he.can look at a charcoal figure and infer that 12 that deposit is a molecular iodine, and he can look at some 13 filters and infer that that is a particulate form of 14 transfer.
So that this much an oversimplification, I want 15 to tell you, because it is not clear particulates can cause 16 it every place.
So it takes a little bit of unfolding.
17 MR. LAWROSKI:
It is really too good of a 18 100-percent material balance.
~
19 MR. WICHNER:
Now, loren: did have a careful 20 material balance.
That's one thing he did have --
21 MR. LAWROSKI:
That would indicate --
22 MR. WICHNER:
-- which was absent in Parker's 23 experiments, but lorenz did have a good mterial balance.
24 Well, the point I would like to make is that in J
25 his experiments ahere he employs helium that he calls a " cap ALDERSON REPORTING COMPANY. INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554 234$
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purge test," now, the range of temperatures less than 2
1100-1200 degrees centigrade, the dominant species does 3 indeed seem 'to be cesium iodide.
In other tests, in steam 4 there was a range of species that are identified.
5 The range I have given here, the low point, the 4 6 percent cesium iodide and the high point I believe I 7 picked the high ones I am not sure.
It's 86 percent cesium 8 iodide.
So that when he ran his experiments with steam, he 9 got a range of percent of cesium iodide, a range on'the 10 location where the molecular iodide would come down, also a 11 range of particulates.
12 MR. LAWROSKIs Excuse me.
I guess it's a 13 different way of expressing material balance from what I am 14 accustomed to.
What that is is of the stuff tha t he 15 measured, that's 100 percent, but that doesn't say that he 16 was accounting for all of the 100 percent of the iodine.
17 It's just that you can do material.
That 's not 18 MB. WICHNER:
Yes.
That's right.
Although he did 19 make comparisons with predicted amounts actually in the 20 fuel.
But these are not those numbers, these are simply 21 percentages of what was observed.
22 So this would go up to 100.
However, the.
23 sta temen t is still true.
24 MR. LAWRCSKI:
Yes.
25 MR. WICHNER:
In comparing these total amcunts I
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1 with what vas in the fuel, he did get good comparisons.
2 MR. ETHERINGTON:
It seems to me important to know 3 how much of the equilibrium iodine-131 is in the voids and 4 presumably found a stable partner and how' much is still in 5 the lattice.
Do we know what that ratio would be?
6 MR. WICHNER:
That ratio, that was measured for 7
two pair of fuel elements.
And for PWR fuel element, the 8 amount of iodine in the void tha t was readily a vailable for 9 departure on fracture of the void was on the order of 1 10 percent, 1 percent of the total inventory in the fuel.
11 MR. ETHERINGTON:
You mean 99 percent was still in 12 the lattice?
13 HR. WICHNER:
Yes, for the PWR experimental pair.
14 I have to emphasire that, b eca u se f or a sinilar pair of 15 tests using a BWR fuel element, that number was 14 percent.
16 HR. ETHERINGTON:
So the assumption that the 17 iodine pairs out with for cesium iodide will then depend on 18 the relative rates of diffision out of the la ttic'e a s well 19 as the relative amounts of cesium and iodine in the 20 l a t tic e.
Is that somewhat indeterminate?
21 MR. WICHNER:
I am sorry, I missed the gist of i
22 your question.
I don't know at what point in the pellet 23 void cladding geometry you generate stable chemical species 24 and at what point you keep these elements apart just simply 25 because cf --
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1 HR. ETHERINGTONs The point was that in a meltdown 2 presumably everything that.is in the void disappears-3 q ui ckly, and that is to say cesium iodide.
'Fow, in'the 4 lattice we still have cesium and-iodine, which are diffusing 5 out at different' rates, and it isn't so clear that we can 6 assume that we will ha ve cesium iodide unless we have some 7 numbers. -Have I made th at clear there?
8 MR. WICHNER:
No, not really.
Let me just say 9 this.
The cesium iodide and other -- and the noble gases --
10 are predicted to be almost completely gone significantly 11 before melt occurs.
12 HR. ETHERINGTON:
Then the distribution at 13 shutdown is very rapidly upset then by increasing 14 temperature?
15 MR. WICHNER:
Yes.
16 ER. MOELLER:
Don Orth.
17 MR. ORTHs Was al1~of.that done on samples'cf the 18 same fuel, dif ferent samples of the same fuel?
i 19 HR. WICHNER:
All of that was done on different 20 samples of two fuel rods, one fuel rod from the Feechbottom 21 boiling water reactor, and one fuel rod from the H. P.
22 Robinson PWR.
23 MR. ORTH:
Rut is there any way we can tell from 24 that table which were from which, or do you have any kind of i
25 a radiation data?
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MR. WICHNER4 Not on this table, but on the table 2 in the report, I believe it is identified.
)
3 MR. M0ELLERs Rich Sherry.
4 MR. SHERRY. Bob, you may want to point'out the 5 difference between the experimental apparatus for the helium i
6 setup and the steam setup which may account for some of the 7 dif ference in chemical fo rm.
8 MR. WICHNER:
Yes.
9 MR. SHERRY I think tha t's important.
10 MR. KABAT:
There is also an interesting 11-coincidence also.
In the case of the report which are 12 indicating that for a larger amount of total amcunt of i
13 iodide we are getting a' higher yield of cesium iodide; here 14 we are in the low quantity, we are getting high, too.
15 MR. WICHNER:
Yes.
16 MR. KABATs And also they are actually shorter 17 periods.
We are getting a higher amount of cesium on cesium 18 iodide; it means that cesium iodide migh t even be in the 19 voids and elemental iodine from diffusing subsequently from 20 the uranium oxide.
That might be.
That would also be 21 actually a point worth -- what we discussed before about the 22 free path of cesium and atoms inside the la ttice.
It means 23 that the iodine would be reacting so much in the voids.
24 There are quite a f ew cases like that in the table 25 and the report.
And it might be worth analyzing it from
)
l l
i f
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this point of view.
'2 MR. WICHNER I was getting to the point of
(
3 setting down some postulates that could explain this 4 behavior.
I noted what you have said.
However,-I did not 5 use that as an explanation.
6 MR. ETHERINGTON4 Jim, I would like to try another 7 tack on my previous question.
Assuming that immediately we 8 get o ve rhea ting, every thin g in the void disappears, we still 9 have cesium and iodine in the lattice.
If that iodine in 10 the lattice was a large proportion of the total shutdown, do 11 ve know there is enough cesium in the lattice to take care 12 of it?
13 MR. WICHNER:
To take care of what?
14 MR. ETHERINGTON:
Do we know there is enough 15 cesium in the lattice to satisfy the iodine in the lattice?
16 MR. WICHNER:
Yes, I think that's clear.
There 17 are about 10 times as much.
10 MR. ETHERINGTON:
No, no.
That's the total.
But 19 ve don't know how much of that is in the voids and how much 20 is still in the lattice.
21 MR. SHERRY:
I think the observations that were 22 m ade on the higher-tem perat ure tests, which were as much as 23 20 percent of the cesium and iodine were released durino the
- 7 24 test, indicated that there were -- or most of the release 25 was coming from the grain structure itself.
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1 observations were that the total fraction of cesium and-2 ~ iodine being released were approxima tely the same, about 20 3 percent.
4 And based on the overabundance of cesium, you 5 would expect that about 10 times as much cesium coming off 6 the UO2, coming fro's the UO2 grains..
7 MR. ETHERINGTONs You said-that awfully fast and' 8 also I.didn't hear it very well.
9 ER. SHERBYa In the higher-tempera ture tests, the 10 test.was compared to 216 degrees C.
There was a. total' 11 release of approximately.20 percent of the available 12 inventory of both the iodine and cesium.
Okay?
And they 13 came off about the same rates.
And since there is 14 approximately 10 times as much cesium as iodine, okay, and l
15 they're coming off about the same rate, there should at all 16 times be an abundance of cesium for a combination of iodine 17 if they are combined prior to release.
18 MR. ETHERINGTON:
Let me probe a little further.
19 At shutdown, essentially all of the iodine is in the 20 lattice.
Now, if one-tenth of' the cesium is in the lattice, 21 then we've got enough cesium there.
Do we know that there 22 is one-tenth of tne cesium in the la ttice a t shutdown?
23 MR. SHERRY:
Well, the gap inventories of cesium 24 and iodine during normal operation should be approximately 25 the same.
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MR. ETHERINGTON:
In the gap.
2 MR. SHERRY:
In the gap, yes.
i 3
MB. ETHERINGTON:
Now with tne ratio in the 4 lattice 5
MR. SHERRY:
A p p ro xim ately the same as in the 6 gap.
To the firsi, order --
7
!!R. ETHERINGTON:
You're saying they diffuse at 8 the same rate?
j 9
MR. SHERRY:
Yes.
1 10 MR. ETHERINGTON:
That's very surprising, because 11 cesium has an atomic radius enormously grea ter than the 12 radius of iodine.
13 MR. SHERRY:
The two top tests were tests to 14 measure the gap inventory of cesium and iodine, and these 15 indicated tha t the --
16
'MR. ETHERINGTON:
I see.
l 17 MR. SHERRY:
-- f raction of the a vailable 18 inventory that got to the gap was about the same for cesium
~
19 and iodine.
7 1
20 MR. ETHERINGTOFs Okay.
If you have firm numbers i
i 21 there.
f 22 MR. WICHNER:
In looking at this table 23 MR. MOELLER:
Well, now, had you done what Dr.
24 Kabat asked about on the type of analysis that he 25 succested?
i l
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MR. WICHNER:
By that you mean?
2 MR. MOE1LER:
Looking at the total quantity and 3 looking at the time f actors and so forth.
4 MR. WICHNER:
No.
I presume you mean looking at 5 the behavior of migrating species within a UO2 crystal.
No, 6 I haven't done that.
And f urthermore, I am not quite sure 7 how that could be done.
That's quite a difficult job.
8 MR. KABP.T:
I believe that in the voids actually 9 because it's gaseous phases, the iodine and cesium would be 10 in the form of gas, gaseous forms.
So that probably th e 11 reaction probably would be much better because of the f ree 12 path.
13 MR. WICHNER Yes.
14 MR. KABATs So that eventually that would affect 15 the ratio of cesium iodide to elemental iodine in voids, 16 while ln the crystalic structure of UO2, it wouldn't have so 17 much chance.
18 And the other thing, also, the half-life of 19 iodine-131 is relatively short compared to the dynamics or 20 kinetics of that action between cesium iodide.
So it means 21 it really wouldn't have -- it's diffusion-controlled in this 22 case.
And at today's half-life, that would give us actually 23 less chance to get a inter-reaction than, say, the stable 24 iodine atoms.
25 So this way, actually, probably the ratio of ALDERSoN REPORTING COMPANY,INC.
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elemenatal iodine to cesium iodide would be different in the 2 matrix, UO2 matrix, than in the voids.
And this would 3 eventually indicate that it might be the case.
4 MR. LAWROSKI How reproduceable are those, do you 5 know?
I am looking at the steam at 900, I guecs.
Ihose 6 three are at 900.
They're on two different kinds of fuels, 7 I guess, because of the amount of iodine reducing -- the 8 last pair is a common sample, and then the other one is 9 not.
If it isn't, then I have some questions about the 10 reproduceability.
11 MR. WICHNER:
These are very difficult 12 expstiments, and one-shot experiments.
13 M R. LAWROSKI I agree with that, yes.
14 MR. WICHNERa And testing for reproduceability is 15 frequently not a luxury that is afforded people.
16 MR. LAWROSKIs Because if it was indeed the same 17 sample of f uel, those three you looked at, then you get a 18 crszy pattern there that leaves you with a great deal of 19 uncertainty as to what's going on.
20 MR. WICHNER These may involve phases in the test 21 series where the temperatures approached and allowed the 22 pla teau and then subsequently elevated and left the pla teau,
explain why some of these 23 and that tends to emphasize 24 large differences.
Some of these migh t refer to a plateau 25 _i n a series of tests and not necessarily to inventory of the ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554 2345
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fuel rod.
2 Put I just wan ted to get to some postulated 3 reasons for this behavior, and there was one such given a 4 moment ago.
5 (Slide.)
6 One possible reason for this behavior, if we look 7 at the last two experimen ts, the last pair, we see under 8 nominally similar conditions, similar amounts of iodine.
9 When we run the experiment briefly, va get proportionally 10 more cesium iodide than if we run the experiment for a long 11 period of time.
12 Okay.
So you can form a postulate th a t the cesium 10 iodide has some finite reaction time with the environment, 14 say, steam or impurities in the steam, so that the long-ters 15 experiements tend to degrade the cesium iodide to form the 16 molecular form.
Okay, that's a postulate.
17 The other postulate is that the steam in this 18 experiment was not chemically pure, it did contain -- ther 19 used demineralired water, but they didn't purify it 20 otherwise.
And if there is a reaction with an impurity, it 21 would tend to have an effect whenever you have a staller 22 amount of iodine involved.
23 So I do observe this thing that was mentioned a 24 minute ago that you have cases where not vastly different 25 conditions, b.u t when you have small quantities of iodine, ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON. o.C. 20024 (202) 554 2345
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you tend to manufacture larger observations of molecular 2 iodine from that point of view.
3 And the third possibility is that in this 4 experimental system, which consisted of quartz, it is 5 possible to get some interaction with the quartz, and you 6 have, between the steam experiments and the helium 7 experiments, a different type of geometry that allows more
- 8. of a contact with quartz.
So that is also a possibility 9 with the reaction with cesium iodide with quart: vould tend 10 to lock the cesium in the quartz and allow the iodine to 11 dissolve.
12 MR. STEINDLER:
You're not saying that experiments 13 at 1600 degrees centigrade were done in quartz, ar.e you?
14 MR. WICHNER:
No, the boundary tube was quartz, 15 however, and the carrier gas convected past the quartz.
16 MR. STEINDLER:
Do you know anything at all about 17 the impurity content of the steam?
18 MR. WICHNER:
It would be ppm level air.
That 19 would be the impurity content.
There was no special pains 20 taken to de-aerate, that's all.
21 MR. STEINDLER:
Is that righ t ?
I guess my 22 conclusion on that' basis is most of those experiments won't 23 mean much.
24 MR. WICHNER:
No.
I think that will -- that might 25 prove to be true, but the indications a re tha t higher oxygen 1
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levels in what you would normally get f rom dissolved air and l
2 water would be. req uired to alter chemical species.
But that 3 remains a not completely resolved question.
4 MR. MOELLER:
Don Orth.
5 MR. CRTH:
Well, I mean with all of the caveats 6 that keep coming in on this, is it -- would it be fair to 7 say that these particular data as reproduced in Table 4.3 8 and your table and your book here really aren't very-good in 9 terms of trying to make any of these interpretations?
10 MR. WICHNER:
Well, I wouldn't put it that way.
11 They're a step forward, and whenever you take a step 12 forward, you recognize things that if you were that smart in 13 the beginning you would have done differently.
14 MR. CRTH:
Right.
And from the standpoint, 15 though, it's fine.
There is a lot of interesting points.
16 You can postulate the reasons as you did for why two series 17 of tests you got those two results.
18 MR. WICHNfR:
Right.
19 MR. ORTH:
However, those data are only useful if 20 then you can go on and design some experiments and confirm 21 that those explanations really are any good.
22 MR. WICHNER:
Richt.
23 MR. ORTH So my reaction on readina this the 24 first time -- because now I am beginning to remember the t
25 original reports, because I think I read some of those ALDERSON REPORTING COMPANY,INC, I
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were that they were very interesting from the standpoint of 2-planning tests.
But you still couldn't draw any conclusions 3 from them.
4 MR. WICENERs' Well, I would agree with that.
If 5 one were aware of these possible phenomena that are 6 illustrated in the results at the outset you would have 7 designed the experiment dif ferently.
8 MR. OBTH:
Correct.
So they are valuable for that i
9 purpose.
But I guess wha t I am really wondering about then, 10 does this table and a few of the others like it really have 11 any input into what our general conclusions are as you have 12 put them in this chapter?
Because if they do, they call 13 those " conclusions."
4 14 MR. WICHNER:
Well, you've got me on the spot a 15 little bit.
16 MR. MYNATTs Fred Mynatt, from Oak Ridge.
l 17 Almost all of-this discussion is focused on the 18 steam part of this table, and when you get to the point of 19 questioning the experimental technique, that's appropriate, 20 because the best experiments were the helium and steam purge 21 experiments.
22 And if you turn the question around and say for 23 those experiments which have the best exp erim ent al 24 technique, if the form is a tomic or molecular iodine, how 25 could that have been observed in the analytical train?
And e
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.1 that is the firmest piece of evidence, I think, in the 2 experiment.
3 MB. ORTH:
Right.
But we are also interested in 4 the overall conclusions on accidents that involve, in many 5 cases, having a large amount of steam there.
It's hard to 6 have a water reactor and have no water whatsoever present.
7 MR. MYNATT Yes.
It's important to take the 8 questions one at a time.
I certainly don't reduce the 9 emphasis on that question.
I just did it one at a tim'e.
10 MR. ORTH:
I don' t question the data here.
As I 11 point out, it's interesting data from the standpoint of 12 designing e xpe rim e n t s.
You can draw a lot of' conclusions 13 that are very worthwhile as far as designing the next 14 experiment.
I just worry about using it right now to draw 15 conclusions on pathways and migration rates.
16 MR. STEINDLER:
There is one other hooker, 17 though.
You've got to be very careful when you make that 18 statement.
That's a selected table, and he carefully 19 pointed out you ought to go to the text.
20 If you go to the text, you find it is two kinds of l
21 experiments.
It's helium experiments and gap purge 22 experiments.
The other ones are not.
And unless you do a i
23 lot more talking or reading, you can't compare necessarily
)
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of what you have on the slide, I think, is a little 2 hazardous.
3 MR. MOELLEBs Harold Etherington.
4 MR. ETHERINGTON:
Yes.
I would like to understand S those last two lines.
As I understand it, in the final 6 tests the extra 60 minutes of heating only released an extra 7 three ' milligrams of iodine; is that right?
8 MR. WICHNER:
I am not familiar with the exact 9 chronology of each individual test.
I don't know.
I would 10 have to look at the chronology of the tests to be able to 11 answer any question that is that specific to the test 12 sequence.
13 MR. ETHERINGTON Well, then, I will-ask a 14 hypothetical question.
If this is true, then it doesn't 15 seem reasonable that an extra three milligrams can so 16 radically ch'ange the cesium iodide and iodine distribution.
17 So I will just drop it there, as long as we don't want to 18 discuss it.
19 MR. KABAT:
Was this iodine released from one 20 element?
21 MR. WICHNER:
It was released from two from 22 segments from two discharges.
23 MR. KABAT:
So that the five grams actually in two 24 experiments, an order of one gram from the other 25 experiment?
That's quite a large amount of iodine.
That ALDERSON REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554 2345
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would represent probably almost a total release of iodine 2 from the fuel.
3 MR. WICHNER:
The experiments, as they ended up at 4 tha upper temperature levels of 1200 or so above, most of 5 the iodine would end up in-the vault, yes.
8 MR. KABATs That shows really a very ra pid rise.
7 A few hundred minutes, a rapid release of all the iodine 8 from the fuel into the steam.
9 MB. WICHNEas Yes.
Right.
I have some release 10 rate coefficients, but I am not sure how much time you want 11 to give me.
12 MR. MOELLER:
I was going to ask you where you 13 stand.
Mr. Kress still has to appear; is that correct?
I 14 know we have delayed you with questions.
But let's do move 15 along.
18 MR. MYNATTs Fred Mynatt again.
17 Let me resta te the conclusions that I think boil 18 down from this discussion. Ihat is, for the gap purge 19 experiments.
The helium test, the observed form is not 20 molecular iodine.
Strongly suggestion f rom analytical and 21 cesium iodide, but that's not a definitive measurement for 22 the steam test.
23 The conclusion, I think, that comes from this 24 discussion is -- our observations -- is tha t the 25 experimental technique har to be much more caref ully done in ALDERSoH REPORTING COMPANY, INC, 400 VIRGINIA AVE., S.W., WASHINGTON, D.C. 20024 (202) 554 2345
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order to get real conclusions, so you can see we're not 2 really getting all tha t much from this table.
But on the 3 other hand, it is very important that in one very clean case 4 it is not molecular iodine.
5 MR. MOELLER:
How much more do you have ?
6 MR. ETHERINGTON Could I just ask one more 7 question quickly?
Was the last table included in the 8 report?
9 MR. WICHNER:
Yes.
10 MR. ETHERINGTONs Looking at Lorenz' more recent 11 publication, his numbers are on micrograms.
You might want 12 to check to see whethe r tha t milligrams is correct on the 13 table.
14 MR. WICHNERa I am pretty sure it's milligrams, 15 but I will check that.
16 MR. ETHERINGTON:
Some of this goes down to five 17 grams.
Ihat's a lot of iodine.
18 MR. WICHNER:
Well, all right.
Thank you.
Okay.
19 Thank you.
20 MR. MOELLER:
If you can finish your part up in 21 ten minutes or so, go ahead, Bob.
j 22 MR. WICHNER:
Okay.
23 (Slide.)
l 24 I think I have covered, I think, the rest l
25 important area, and very briefly I would just like to look i
l 1
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now at relative release rates, sort of leading into Tom 2 Kress' part of the talk.
I just would like to say that we 3 have examined a host of -- well, not a host -- but many 4 release rate experiments.
And I think these are all that 5 pertain to materials other than noble gases.
Each has 6 different characteristics, and I have to mention that 7 somewhat to indicate some of the subsequent uncertainty.
8 Each represents some sort of a compromise, and the 9 experimental conditions affect the results in different 10 ways.
And the results, on the surface, is confusing.
And 11 even below the surface it's confusing.
12 But in Lorenz' experiments, he actually used 13 discharged f uel, a nd the environment was helium and steam.
14 Parker used chunks of low-burning fuel and helium.
He also 15 had some melt exp'eriments.
We used the causal experiments.
16 These used fuel simulants, which have a set of uncertainties 17 introduced therefore, and their experiments are 18 predominantly in air, which alters the chemical species.
19 And now there is generating some steam experiments.
20 We have the power burst facility tests and 21 reacter.
Davies used low-burner material, powders, and 22 compacts and helium and so on, where you have in each 23 experiment either a burn-up effect, a chemical form effect, 24 a cladding, existing or nonexisting.
And in-reactor tests 25 involve problems of their own.
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But what we did to obtain relative release rates, 2 we emphasized for this study the first four studies.
3 (Slide.)
4 And while the result is conf using at first, there 5 does seem to be some sort of a pattern.
These results are 6 expressed as release rate coefficient, fraction release of 7 romaining uncontrolled for a minute, and this curve for the 8 noble gases and the volatiles indicate some trend that we 9 axamined, the individual experiments, qualitatively tried to 10 note their biases, and from that scatter attempted to define 11 an in terim release rate coefficient for iodine, xenon, 12 krypton, and cesium, based on these individual tests, which 13 are a function of temperature.
I 14 (Slide.)
15 And from these uncertainties that we have come up 16 with this, which I would just like to present as our what I 17 would call an "in terim " set of release rate coefficients 18 from fuel based on a partial examination of the body of 19 data.
You might correct "rine" there at the bottom.
That 20 "ZN" should be "ZR."
21 This set of curves applies.
It does not apply to 22 the release part to the burst release and to the shallowly 23 embedded release, but to the subsequent release.
24 Well, I think I will end my talk at this point.
25 MR. MOEllER:
Are there any other questions?
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(No response.)
2 MR. MOELLER:
Okay, let me ask how long Tom Kress' 3 presentation will be?
4 MR. KRESS:
I had planned about a 20-minute talk.
5 MR. MOELLER:
All right, I think we will go ahead 6 with it now and break for lunch after you finish.
7 (Slide.)
8 MR. KRESS Tom Kress, Oak Ridge Laboratory.
9 The part I worked on and will discuss is the 10 calculation of release rates of fission products and other 11-materials.
That includes fuel, clad, structure.
As the 12 core heats up and passes through melt and is sustained at 13 some melt temperature.
14 In addition, if I have time I will talk about the 15 release from concrete and molten fuel, interacts with as it 16 falls through the vessels.
17 (Slide.)
18 The release calculations in this study are 19 somewhat different from the original reactor safety study.
20 And so that you can notice that those differences and more 21 or less highlight them a little bit, I have one slide which 22 I would like to present.
23 (Slide.)
24 This reviews briefly what was done at the reactor 25 safety study.
In that study, if you look a t some small 1
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1 coherent mass of fuel that is heating up to melt, then it 2 was assumed that there was no release from that part of the 3 fuel.
I am not talking about gap releases.
This is 4 subsequent to that.
There would be no release from that 5 part of the fuel until it was f ully molten.
And at that 6 time you would instantaneously release some fraction of its 7 inventory.
8 If you combined that then with the rate at which 9 the different parts of the core become molten, putting the 10 two together and multiplying this release fraction times the 11 fraction molten, you get a timed rate of release of the 12 total mass of the inventory.
13 I wanted to emphasize that this high rate of 14 release is strictly governed by the rate of the core 15 melting, and the total quantities is strictly governed by 16 this release fraction, which was established based on some 17 early experiments and based partially on volatilities of the 18 various fission products.
19 The experiments that Bob Wichner discussed --
20 (Slide.)
21
-- were observations that you don't have to wait 22 for the fuel to get completely molten before you release 23 materials.
We have releases on both sides of the melting 24 point as it's being heatea up and after it melts.
And the 25 observations are that the release, the mass release, ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W. WASHINGTON, D.C. 20024 (202) 554 2345
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decreases more or less exponentially if you hold the fuel at 2 a fixed temperature and not let it heat up.
3 This temperature can be below or above the melt.
4 This increases exponentially.
But it will continue in time, 5 and it may even approach the total inventory if you held it 6 at that temperature long enough.
7 This suggests a release equation in this form 8
(indicating).
The release rate is proportional to the 9 inventory that is there times some coefficient.
And this 10 was the definitionof this release rate coefficient that Bob 11 presented as his best estimate values from the set of 12 experiments that he looked at.
13 This is the approach that I used in estimating 14 these releases.
15 (Slide.)
16 Taking these, once again showing Bob Wichner's 17 table, I am showing there is continuous release as the core 18 heats up and passes through melt and even beyond melt as it 19 continues to hea t up.
20 (Slide.)
21 We do recognize, however, that different parts of 22 the core heatuo at different rates and melt at different 23 times during the accident sequence.
So the question is how 24 do we use these strictly empirically established release 25 rate coefficients on a whole-core basis to account for this j
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'128 1 -fact that the core heats up differently and melts 2 selectively at different parts?
3 What I would like to:have done was having a 4 thermohydraulics analysis that calculted the temperature 5 distributions in space and time within the core, couple that 6 with this release rate type equation with these coefficients
~
'7 and how this code acted together. to produce release rates at 8 a function of time for each of the isotopes.
9 Unfortunately, we didn't have this luxury in this 10 study, because the codes, the thermal dynamic codes are not 11 confined to such release rate equations.
So I was forced to 12 try to do this by hand calculation.
I computerized it, but 13 it was more or less a mechanized hand calculation.
14 (Slide.)
15 And to apply the equations, we used t'wo sequences, 16 the AB sequence and the 52 sequence.
And I think I will 17 just show you the S2C sequence, in the interest of being 18 brief.
19 We do need thermohydraulic calculations.
We do 20 need the rate at which. the core heats up and becomes 21 molten.
This is the-results of a Ma rch computer code 22 calculation.
I am not going to dwell on it.
This is the 23 time from the start of the accident, the delayed sequence in 24 which th,e melting only starts well within the accident.
f f
25 But the point I want to make on this slide is this 1
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1 gives the fraction of the core that is within a given 2 temperature increment.
And the temperature increments are 3 shown up here plus or minus 100 degrees.
4 The point that I want to make here is that this, 5 in general, does give you percentages of teh core that are 6 in particular temperature environments as a function of 7
time.
However, we don 't knov from this kind of output 8 whether this particular part of the core passed directly and 9 became this part later on.
10 So it is not really specific for given locations 11 of the core.
And in order to make calculations, we were 12 looking at release -- that is, a f unction of the current 13 inventory -- I really need these temperature histories that 14 would look a t a specific chunk of fuel and follCW its 15 complete history.
16 So what I did, in essence, was synthesize this 17 kind of result 18 (Slide.)
by an analytical function that looks like 19 20 this.
I replotted the da ta on that table.
This line 21 (indicating) is a fraction of the core as a function of i
22 time.
That is, above a thousand degrees centigrade.
For 23 the really significant release starts.
The second line is a 24 fraction of that core above 2200 degrees centigrade, which 25 was the upper limit on the table.
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The thing I wanted you to notice on these twc 2 (indicating) is that when a given percentage of the core, 3 like going' f rom two-tenths to three-tenths af ter it reaches 4 a thousand degrees, the amount of time for that percentage 5 to then arrive at 2200 degrees is not much different during 6 the whole course of the accident.'
7 And, in essence, then, what I did was say once it 8 reaches to a thousand degrees, I will assume a heat-up of 9 about 80 degrees C per minute, which is the difference 10 between these two divided by-this time and assume that that 11 heat-up rate is linear.
12 I can als6 combine that with, if we look at this t
13 part of the curve and linearize that by this ra te, this 14 tells me how fast parts of the core arrive at the thousand 15 degrees before they begin to heat up.
By combining this 16 curve with this linear heat-up (jndicating), I get a set of 17 numbers that lcok a lot like it in that table.
It is an 18 approximation to the 52C accident sequence in terms of the 19 time-temperature history of the core.
20 (Slide.)
21 Given that type of time-temperature history, then,
]
22 I want to apply this new type of release rate equation.
And 23 I did it as follovsa To aid the analytical process, I took 24 this best-estimate release rate coefficients, if you recall l
25 those, the empirical data taken from the experiments, and I 1
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approximated them analytically.
If you recall, it was a 2 semi-log plot release rate, a release rate coefficient 3 versus temperature.
4 You get that sort of equation for a straight 5 line.
So I approximated them by two different straight line 6 over two different time intervals, although that is not made 7 clear.
8 So this then would give one a release rate 9 coefficient which would be specific for a given isotope, 10 where the A and the B define the isotope release rate.
Sc 11 it's an analytic representation of these release rate 12 coefficients.
13 The temperature transient, as I said, I linearized 14 the heat-up 1000 degrees on up to as far as I wanted to go.
15 So this would be the 80 degrees per minute (indicating), and 16 this would be the thousand degrees here (indicating) in that 17 linearized approximation.
18 I still haven't said how I used the rate at which 19 I arrived at the thousand degrees, but I will talk about 20 that in a moment.
21 If you put this in through the temperature and use 22 release rate equation -- but this, by the way, should have a 23 minus in front of it, which was left off, and this double 24 equation should be a minus also.
25 If you put that into this equation, it becomas ALDERSoN REPORTING COMPANY,INC, 400 VIRGINIA AVE., S.W., WASHINGToH D.C. 20024 (202) 554 2345 i
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this form, and you can integrate that and put it in the form 2 to.get the total amount released as a fraction of the 3 original inventory.
You get an equation of this form, where 4 the constant, the coefficients reflect both the empirical
-5 data, da ta f or release coef ficient.
It reflects the initial 6 starting temperature, and it reflects the heat-up rate.
7 So this was basically the equation I used to 8 calculate the release of the various fission products, 9-except this assumes that the heat-up rate is applied 10 uniformly for a given portion of the fuel.
So you have to 11 incrementize the fuel and look at specific finite element 12 control volumes, and that is where the rate at which the 13 fuel rises reaches a thousand degrees is used.
14 If you recall, that straight line gave you 2 15 percent per minute arrival of the core above a thousand 16 decrees.
What that means is that every five minutes an 17 additional 10 percent of the core has reached a thousand 18 degrees.
19 If I used the 10 percent of my core as a finite 20 element in my equation, then using that previous equation l
21 for the release rate on an incremental basis when my 22 increments were 10 percent -- that's r.ot a decimal point; 23 thst's 10 percent -- then the equation really looks like 24 this.
25 (Slide.)
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.The one-tenth takes care of the -- well, now, this 2 is a whole-core inventory, so I divided the one-tenth.
I 3 add up all of the incremental releases for each increment of 4
the core, its delayed and its release, by five miniutes 5 because of this five-minute interval, and I still have the 6 same coefficients with the thousand degrees and 80 degrees C 7 per minute.
8 So this is really the equation I use4 to calculate 9 the release based on the empirical established release rate 10 coefficient.
11 I had to computerire it, part of it, of course.
12 Applying that equation with the best-estima te coefficients 13 for the two sequences, you get a set of curves that look 14 lik e this --
15 (Slide.)
for the different isotopes.
This is a fraction 16 17 of the total core inventory now released as a function of 18 time for the S2C sequence.
And this time is measured really 19 from the point on the table which was the point at which the 20 first core element had reached a thousand degrees l
l 21 centigrade.
So it's not the time when we started the 22 accident.
But basically, what we get out of this kind of 23 calculation is the time history of the release of the 24 various parts of the isotopes based on strictly empirical 25 data of small-scale release.
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I left the VUEf. Lurve off of here.
It f alls in 2 between the (inaudible).
3 If then we look at this accident is projected 4 that the core support barrel would fail at about seven 5 minutes, so that at that time the release would be. quenched 8 by the ccre f alling in the water below.
So if you look at 7 the values for the release at that time, you would get and 8 add up all of the materials so that one can establish a 9 total aucunt of release f or each of the sequence --
10 (Slide.)
11
-- you get numbers like f or the AB sequence and 12 tha time of grid plate failure you get on the order of 770 13 to 1000 kilograms.
I wouldn 't attach my significance to 14 these figures here.
The 52C sequence, you get perhaps 1500 15 kilograms at the time of grid plate failure.
18 If we compare the individual release of the 17 different isotopes --
18 (Slide.)
19
-- for the, in this case, the AB sequence, which 20 was more comparable to the things suggested in the RSS --
21 MR. MOELLER.
Excuse me.
Cn the previous slide, 22 you showed the grid plate value predicted by the March code 23 at 20 minutes?
Oh, and then the S2C is the 70 minutes.
I 24 missed the 70.
Go ahead.
I am sorry.
25 MR. KRESS Comparing th e release of individual ALDERSON REPORTING COMPANY,INC.
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isotopes for the AB sequence-at.20 minutes, which is at the'
- 2. time of grid plate failure, you get virtually complete J
3 release of iodine and cesium.
' Surprisingly,-we get 4 virtually complete release of the tellurium; however, it may-5 be c a tenth in the reactor safety study.
6 The rest of the figures are comparable 7 magnituden.
They are somewhat higher.
Barium and. strontium 8 release.and hydrogen release.
But they're the same order of 9 maonitude.
10 There-is a considerable quantity of structure i
11 cladding fuel that is important in.the release because it 12 adds to the total airborne, the aerosols which affect the 13 subsequent transport in the containment.
14 So these released quantities f or the fractions are 15 small, but the total inventories are large.
So that they 18 are very significant in the total release.
17 MR. 20ELLER:
Harold, I don't know if it helps you 18 at all, but at least that chart shows the iodine and cesium 19 coming off at roughly 20 3R. ETHERINGTON It doesn't really tell me, 21 really, what I want to know.
22 MR. MOE1LER:
It 's th e detail you want?
23 MR. ETHERINGTON:
How much was really in the 24 lattice was what I wanted to know, and how much was a gross 25 amount.
It doesn't help me.
But it's okay.
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MR. SHERRY:
I_just want to point out where some 2 o f th e prod ucts in the second group, - the tellurium --
3 MR. MOEllER:
We can't hear you.
4 MR. SHERRY:
I'm sorry.
I just wanted to point 5 out that for the second group of elements, al.though we 8 predict a much larger release during the in-vessel phase in 7 the reactor vessel safety study essentially all of the 8 tellurium was released at the subsequent stages of the 9 accident in the interaction with concrete.
That isn't to 10 say the reactor safety study grossly underestimated the 11 consequences, at least for that group.
12 MB. KRESS:
I think the major conclusion is this 13 calculation is based on newer data f or release rate 14 coefficients, and it allows the process to occur 15 continuously rather than with the melt.
Still, it more or 16 less -- we didn't know that at the start, but it's an 17 important conclusion.
18 MR. STEINDLER:
Could I ask a question ?
I think I 19 got lost in the turn, if you will bear with me.
Ycu've got 20 both iodine and cesium in this last table that you showed 21 essentially complete released in 20 minutes.
22 (Slide.)
23 It's about 10 times as much cesium as there is 24 iodine.
So the release mechanism can't be by cesium iodide 25 because it leaves you a bunch of cesium left over.
We've j
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heard so f ar the f ocus on cesium uranate through steam 2 composition gives you some cesium and another cesium uranate 3 that works-its way up to the line until you get cesium
]
1 4 uranate, if you have enough time, that's fairly stable, to 5 cesium for uraniums.
6 The vapor pressure of that material was trivial, I 7 think, even at,2000 degrees, if I have that right, or at 8 least trivial by that mechanism.
9 What is the way by which ali of ' that cesium gets 10 away from the refractory oxide compounds that are lef t af ter 11 the iodine is gone?
12 MR. KRESSt I don't feel -- would anybody like to 13 comment on that?
14 MR. STEINDLER:
Am I asking the wrong question?
15 MR. WICHNER4 Tha t 's a good question.
I am not 16 sure the answer to that has been thought out, frankly.
17 MR. STEINDLER:
But yet you give a total -- you 18 know, you give a coefficient for cesium release that dumps 19 it all out.
20 MR. WICHNER:
- Yes, believe that's what we say, 21 'yes.
But the step-by-step mechanism whereby that happens 22 has not been completair worked out.
23 MR. STEINDLER:
Well, then, can you tell me a 24 little bit about -- we didn't cover it in detail, but tell 25 me how tellurium moves?
As the volatile oxide?
And, if so, 4
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138 1-how do you account 'for sodium,as the oxide decomposes?-
2 MR. WICHNER:
Well, I wish you-would address'those j
3 questions'to us a'little bit'later.
Some of those questions 4 can 't be answered at this point.
The mechanism for mobility 5 at this stage has not been worked out.
6 As far as, cesium leaving those, as you heat the i
7 uranate, you evolve-the cesium.
If you have a cesium 8 iodide, you vaporize the' cesium iodide;~1f you have the 9 cesium.in the elemental form, you will-naturally at first j
10 evolve the cesium ' metal as the vaporization.
11 All of these things -- at the same time, you're 12 diffusing cesium in'the grain'out towards the surface of the 13 grain, and while this is happening, you're changing the 14 chemical environment, perhaps altering the chemical species 15 tha t would be in equilibrium.
And I haven't mentioned the 16 possibility of interaction in the zirconium with the iodine 17 material.
18 So, as you heat up a host of chemical and physical 19 processes occur -- and I don't mean to avoid your question, 20 but I think it 's f air to say tha t what th ose procestes are 21 have not been worked out.
22 MR. KRESS:
From my viewpoint -- and the
]
23 calculations could be thought of as almost nonmechanistic, 24 strictly empirical, based on small-scale experiments, to get 25 these release rate coefficients.
What the mechanism is for ALDERSoN REPORTING COMPANY,INC, j
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release of deuterium, cesium, iodine, I don't know.
And 2 that may be entirely wrong.
It's based on.small-scale 3 experiments with all the uncertainties.
4 MR. ETHERINGTON:
If it helps any, the tellurium 5 boiling point is only 100 degrees higher than cesium iodide, 6 but that doesn 't. completely answer anything.
7 ER. STEINDLERs I was willing to buy the tellurium 8
dust on the basis of simple inorganic chemistry.
I have a 9 little more trouble with silver, the metallic boiling point 10 is awfully high and the oxide decomposes 11 MR. WICHNERs However, the tests show a very rapid 12 evolution of silver in a steam atmosphere, and it is very 13 surprising.
14 (Slide.)
15 MR. KRESS: -Well, to summarize that part of the 16 calculation, it is significantly dif f erent f rom W ASH-1400.
17 This calculation is different from WASH-1400.
It is based 18 on empirical data for the release rate coefficients, and in 19 general these are best estimates based on p resen t 20 state-of-the-art data.
But the important conclusion is tha t 21 the values used in WASH-1400 for this particular sequence 22 are not much different.
We more or less support those 23 values.
Based on some of the comments that were made, there 24 are large uncertainties in these results.
The release rate 25 coefficients.
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(Slide.)
2 We did have another portion; that is, to estimate 3 the total quantities of materials that migh t be made 4 airborne, the secondary containment as a result of hot fuel 5 falling on.the concrete and interacting.
And we did make an 6 estimate of the material that gets released.
It is strictly' 7 abstract'ed from and based completely on the Sandia results 8 for the' Zion Indian Point, if you are familiar with that.
9 It's almost ve rba tim, word for word.
And the basis for that 10 is that's the only -- -that 's the real quantitative evidence 11 right now, correlations for release of aerosols from 12 concrete as a f uel interacts with that.
13 (Slide.)
14 Just sone comments about t he d a ta.
They observed 15 that the release ra tes were proportional to the rates at 16 which gases got evolved from the concrete that's barged up 17 through the mouth.
They observed it to ba a sharp function 18 of the melt temperature initial f unction as it falls on the 19 concrete.
Titey observed it not to be strongly dependent on 20 the concrete type, but I am not sure what that means nov 21 because I don't know how many concrete types were tested.
22 The important part is this aerosol is composed 23 mostly of nonfuel material.
It comes out of the concrete 24 itself.
25 (Slide.)
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The calculations I summarize on one slide, and I 2 von 't dwell on it.
3 The release rate, as I mentioned, is a f unction of 4 the gas velocity.
It is also a function of the surface area 5 and the concentration in that gas itself.
But this 6 concentration was based on the empirical equation that 7 related the temperature of the melt and the superheat 8 velocity of the gas, which is determined once again by heat 9 transf er calculation, giving the gas released from the 10 concrete as a function of the heat transfer rate.
That's 11 basically the correlation we used.
12 They had to use the computer code to get the heat 13 transfer rates, and the one they used was called WECHSL to 14 determine the Q.
And these quantities are known 15 quantities.
And they're particular to given concretes.
And 16 that gives the gas velocity to go to here (indicating),
17 combined with the temperature to get the concentration in
)
l 18 gas, and then it goes on up to this relationship to get the 19 release.
The results for the AB sequence --
20 MR. 30ELLERs Dr. Lawroski had a question.
21 MR. LAWROSKI:
'ih a t is it you thought was meant by
- 22 the different concrete types?
23 MR. KRESS:
They tested some different concrete 24 types which would have different constituencies in them.
t 25 MR. LAWROSKI:
One of them was the so-called --
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1 MR. ETHERINGTON:
Diff erent aggregates, is that-2 the difference?
3 MR. SALLACH4 My name is Bob Sallach, from Sandia.
4 The two concretes were tested, a basalt-based 5 aggregates and limestone-based aggregates, those were the 8 two.
7 MR. SHERRY:
Limestone aggregate produces more 8 gas.
9 MR. KRESS:
The final slide --
10 (Slide.)
11
-- shows the total release of aerosols as a 12 function of time for the AB sequence in the Zion reactor.
13 In this case, what.you notice is the releases interacted 14 very early.
These are ours, in this case.
There is a 15 rather rapid release early, and it reaches, depending at the 18 value, of about 800 in this case, which added to the 1500 17 kilograms -- well, in fact, it was about 1000 kilograms for 18 the AB sequence, which would give you about 1500 total.
19 That concludes my pre sen ta tion.
20 MR. MOELLER:
Thank you, Mr. Kress.
21 Cuestions or additional questions on this?
22 (No response).
23 MR. MOELLER:
I assume you will be here all 24 afternoon and then tomorrow, too?
25 MR. KRESS:
Yes.
l l
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l NUCLEAR REGULATORY CO.WISSION This is to certify that the attached proceedings before the x
in the :::atter of: ACRS/ Subcommittee on Reactor Radiological Effects
- Date of Proceeding:
March 10, 1981 Docket Nm::bar:
Flace of Proceeding:
Washington, D. C.
were held as herein appears, and that this is the original transcript thereof for the file of the Coc: mission.,
Jane W. Beach Offteial Reporter (Typed)
.s
//
0 1cial Reporter (Signature)
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