ML20141P025
| ML20141P025 | |
| Person / Time | |
|---|---|
| Site: | Three Mile Island  |
| Issue date: | 03/11/1986 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| References | |
| REF-10CFR9.7 NUDOCS 8603180442 | |
| Download: ML20141P025 (80) | |
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, UNITED STATES OF AMERICA -
NUCLEAR REGULATORY COMMISSION In the matter of: COMMISSION MEETING Briefing by DOE on . R&D Results from TMI-2 Cleanup (Public Meeting) Docket No. 9 Location: Washington, D. C. 1 _ 79 Date: Tuesday, March 11, 1986 Pages: ANN RILEY & ASSOCIATES Court Reporters 1625 I St., N.W. Suite 921 Washington, D.C. 20006 8603180442 860311 PDR 10CFR PDR (202) 293-3950 PT9.7
1 D 1 SC LA 1 M ER 2 3 4 5 6 This is an unofficial transcript of a meeting of t'h e 7 United States Nuclear Regulatory Commission held on 8 3/11/86 . In the Commission's office at 1717 H Street, 9 N.W., Washington, D.C. The meeting was open to public 10 attendance and observation. This transcript has not been 11 reviewed, corrected, or edited, and it may contain / 12 inaccuracies. 13 The transcript is intended solely for general 14 informational purposes. As provided by 10 CFR 9.103, it is 15 not part of the formal or informal record of decision of the 16 matters discussed. Expressions of opinion in this transcript 17 do not necessarily reflect final determination or beliefs. No 18 pleading or other paper may be filed with the Commission in s 19 any proceeding as the result of or addressed to any statement 20 or argument contained herein, except as the Commission may 21 authorize. 22 23 24 25
1 1 UNITED STATES OF AMERICA 2 NUCLEAR REGULATORY COMMISSION 3 --- 4 BRIEFING BY DOE ON R&D RESULTS FROM 5 TMI-2 CISANUP 6 --- 7 PUBLIC MEETING 8 --- 9 Nuclear Regulatory Commission 10 Room 1130 11 1717 "H" Street, N.W. 12 Washington, D.C. 13 14 Tuesday, March 11, 1986 15 16 7he Commission met in open session, pursuant to 17 notice, at 2:05 o' clock p.m., NUNZIO J. PALLADINO, Chairman of 18 the Commission, presiding. 19 COMMISSIONERS PRESENT: 20 NUNZIO J. PALLADINO, Chairman of the Commission 21 THOMAS M. ROBERTS, Member of the Commission 22 JAMES K. ASSELSTINE, Member of the Commission i 23 FREDERICK M. BERNTHAL, Member of the Commission 24 LANDO W. ZECH, JR., Member of the Commission 25
2 1 STAFF AND PRESENTERS SEATED AT COMMISSION TABLE: l 2 S. CHILK 3 T. ROTHSCHILD 4 J. VAUGHAN 5 D. McPHERSON 6 J. BROUGHTON 7 D. McGOFF 8 9 10 11 l , 12
- 13 14 15 16 17 18 19
) 20 21 22 23 24 25
~~
t 3 1 PROCEEDINGS i 2 CHAIRMAN PALLADINO: Good afternoon, ladies and 3 gentlemen. This afternoon the commission will be briefed by 4 the Department of Energy on results to dato of research and 5 development efforts involving the TMI-2 reactor. i 6 Such data will be valuable in developing better 7 means for accident prevention and mitigation and for reducing I 8 the uncertainties associated with requirements for plant 9 design and operation. 10 More specifically, such date could have significant 11 impact on NRC's source term assessment, emergency planning 4 12 guidelines, equipment qualification for accident environments 13 and related policies. 14 To present DOE's briefing Mr. Jim Vaughan, acting
- 15 assistant secretary for nuclear energy, is here to provide a 16 brief introduction. He will be followed by Don McPherson, 17 TMI-2 accident evaluation program manager.
i 18 Also from DOE is Mr. Jim Broughton, project manager 19 for EG&G Idaho and Mr. Dave McGoff, director of the office of i 20 light water safety and technology. 21 We very much appreciate having all of you here today l 1 22 to discuss DOE's TMI-2 program efforts and we welcome you. 23 Before I turn the meeting over to Mr. Vaughan, I would like to 24 ask that in addition to the technical aspects of DOE's R&D 25 program you might address the availability of adequate funding j
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4 1 to complete the R&D efforts in what you consider a 2 satisfactory manner. 3 Now let me ask, do other commissioners have any 4 opening remarks at this time? 5 (No response.) 6 CHAIRMAN PALLADINO: All right, then let me turn the 7 meeting over to Mr. Jim Vaughan. 8 MR. VAUGHAN: Mr. Chairman and Commissioners, we are 9 pleased to have this opportunity to app 3ar before the 10 Commission to describe the Department of Energy's TMI-2 11 accident evaluation program. We appreciate the support for 12 this program that has been shown by the Commission in your , 13 recent letter, Mr. Chairman, to Secretary Harrington. 14 The Department of Energy is pleased with the efforts 15 to date by all parties cooperating with General Public 16 Utilities in the TMI-2 cleanup and the related accident 17 evaluation program. 18 In response to your query, we do plan to continue 19 adequate funding of this program while simultaneously 20 continuing to meet our commitments to provide R&D support to 21 the defueling and core shipping programs at TMI. 22 The $12 million dollar funding request in our fiscal 23 year 1987 R&D budget and the eight million planned in fiscal 24 year 1988 will complete our planned commitment for augmented 25 funding of this TMI-2 program.
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5 1 DOE plans to continue its presence at the Island 2 through completion of core removal, estimated by the end of 3 fiscal year 1987. The core examination efforts at the Idaho 4 National Engineering Laboratory will continue through fiscal 5 year 1988. 6 COMMISSIONER BERNTHAL: Jim, if I can interrupt for 7 a second, you folks, I realize operate under a slightly 8 different budget constraints and rules necessarily as direct 9 members of the Executive Branch than we do here perhaps but if 10 I went to Idaho Falls tomorrow and asked the engineers there 11 whether they are going to be able to have available all of 12 the funding that reasonably should be expected to gather the ,, 13 scientific date that clearly are there for the taking at TMI-2 14 and associated debris and what not, are you confident now that
- 15 we have the fynding that we are going to get all of the i
16 information and knowledge out of that event that we should be 17 getting? 18 MR. VAUGHAN: I am not sure that if you ask each and 19 every engineer working on the program that you get that 20 answer-- 21 COMMISSIONER BERNTHAL: Taking a rough average. 22 MR. VAUGHAN: I believe if you asked the management, 23 they would tell you that there will be enough funds to do 24 that. If as we get into the program with the plans that exist 25 to evaluate it, it should turn out that there are identified 9
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l 6 i 1 some additional things that need to be done because you are ! 2 finding as you go, our overall safety and licensing budget , 3 that continues from year-to-year and is somewhat centered in l 4 Idaho, should be available to accommodate that just as we are 5 accommodating the post radiation exam of the loss of fluid 6 test results in our continuing generic budget. 7 COMMISSIONER BERNTHAL: All right. I just want to ! 8 re-emphasize and the Commission as a body has emphasized it in 9 the letter, I know, but we just cannot afford, I think, to be 10 cutting this area of fundamental knowledge. It could have
! 11 been a better instrumented experiment but nevertheless, the 12 experiment was carried in a way that was not very desirable ,
i l 13 but it is there now and if there is anything at all more that 14 this Commission or I personally can do to drive that point 15 home, I believe the Commission should do that and I will ! 16 certainly help you do it. 17 It is just too important to let that knowledge fall l 18 by the wayside. 19 MR. VAUGHAN: We appreciate that offer of support. 20 I can assure you that our objectives in completing h in a
- 21 thorough and adequately technical and scientific manner are 22 equal to yours.
23 COMMISSIONER BERNTHAL: Good. l 24 MR. VAUGHAN The plans for the shipment of the j 25 core debris from the site is an effort to which we have also 1
, 7 1 paid particular attention. In this regard, I want to express
- 2 my appreciation for the prompt review that 3 NRC staff has 3 applied to the certification of the special ..2pping cask 4 which has been develop 6d by DOE for transportation of the TMI 5 core debris to the Idaho National Engineering Laboratory where 6 it will be examined as we just discussed. 7 I understand that all the issues regarding that j 8 , certification have now been resolved with the staff and that a ,
; 9 certificate of compliance is scheduled to be issued by NRC
\
10 later this month. That is an important milestone to support 11 the shipping campaign which is scheduled to be underway this 12 June. ) . 13 We share with industry and with the commission the l l 14 strong desire to evaluate, disseminate and apply the valuable ] 15 safety and technology lessons being learned from the TMI-2 l 16 accident. Through this approach we can continue the efforts i 17 to assure rational regulation of reactor safety and emergency 18 planning which can continue to protect public health and
, 19 safety with balanced and technically sound approaches that 20 are not an undue burden on the operators of nuclear power 21 plants or on the ratepayers who are the very public being 22 protected.
i 23 In addition to the severe accident analysis effort, 24 valuable lessons are being learned for waste handling and 25 disposal activities as well as decommissioning activities.
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i 8
- 1 As you well know the TMI-2 accident confirmed that
. 2 in spite of severe core damag'e, there are mechanisms to retain l
- 3 large proportions of the fission products and to prevent their 4 release to the environment.
5 Data from our accident evaluation program should be i i 6 'of great value in both developing and confirming our i j 7 understanding of severe accidents., l 8 We expect this to occur by means of corroborating 9 and extrapolating results fron planned experiments such as
- 10 those performed recently in the power burst facility and the 11 loss-of-fluid test program and by providing a sufficiently ;
12 clear understanding of this accident that it may be used to i 13 benchmark severe accident calculational tools and models. l 14 From our perspective, the most important use to l 15 which the results can be put is in the regulatory arena. It 16 is important to DOE that, based on these and the results from i . l 17 many other related programs now in progress, that the NRC be i 18 able to press ahead with regulatory changes that are possible i 19 now or in the near future while we continue to refine the date , 20 base as new data becomes available. . t 3 21 With respect to the execution of the TMI-2 accident j
- t 22 evaluation program, I would like to specifically note that the !
i cooperation with NRC under an e7reement that includes our two i 23 l 24 agencies, General Public Utilities and the Electric Power ! l 25 Research Institute has been very good. The staffs have worked , 4
4 9 1 well together on a good solid technical basis. 2 Continuing participation by a group of Japanese 3 utilities and industries is also valuable in evaluating and 4 disseminating the data on an international basis. We 5 appreciate particularly the help NRC has provided in 6 formulating the TMI-2 core examination plan and in performing 7 some of the fuel debris examination. 8 Further, it is worth noting at this time that the 9 Department has recently concluded an arrangement with the 10 Nuclear Energy Agency for several foreign countries to 11 participate in the examination of T-2 debris and in 12 be.chmarking their severe accident computer , codes against the 13 accident scenario which has been developed through this 14 program. 15 Finally as a last comment, assuring that we keep the 16 public well informed is also an important aspect of this 17 effort and I am pleased, Mr. Chairman, that you, GPU officials 18 and I were all able to participate in the public television 19 report on TMI-2 which is being prepared by Penn State 20 University for airing later this month. We think that is a 21 very positive step. 22 This concludes my opening comments and perspective. 23 Dr. McPherson has been in charge of our loss-of-fluid test 24 examination program for a number of years and is also in 25 charge of our TMI-2 severe accident program to help match
i 10 1 those two efforts together and he has prepared a presentation 2 for you largely using viewgraphs to help in understanding what 3 has happened. 4 CHAIRMAN PALLADINO: May I ask you, what is the 5 nature of the participation? Were these NEA countries? 6 MR. VAUGHAN: Yes. 7 CHAIRMAN PALLADINO: Are they providing funds or are 8 they participating just in evaluating their codes? 9 MR. McGOFF: We expect that some of the NEA 10 countries will perform analyses on TMI debris and share the 11 results with us. We will provide samples and they will do the 12 . analyses. 13 CHAIRMAN PALLADINO: I see. All right. 14 MR. McGOFF: It will augment our program. 15 CHAIRMAN PALLADINO: thank you. Mr. McPherson.
- 16 MR. McPHERSON
- Thank you, Mr. Chairman, and thank 17 you, Mr. Vaughan.
18 (Slide.) 19 MR. McPHERSON: Jim Broughton will help me in my 20 presentation by pointing out the features that need to be 21 pointed out that I will refer to. 22 (Slide.) 23 MR. McPHERSON: These are all the same slides as you 24 have in your handouts so that you can look at that, also. Let 25 me go on to the outline now. I will be giving you a very
1 11 1 straight forward simple presentation, giving you first the , 1 2 objectives of our program, the accident scenario and the and 3 conditions that we now understand the reactor to be in. a
- 4 I will describe the accident evaluation program that i
! 5 we have put together and have had help on from NRC, industry
; 6 including GPU and B&W. Then I will and off by telling you the 1 7 schedule of the work we have planned.
8 (slide.) 9 MR. McPHERSON: To begin with, the program I 10 objectives are very simple. We simply want to understand what ] 11 happened during that accident, no more than that to a degree, i ) 12 where we understand the consequences as they apply to the
?
13 issues at hand today.' I 14 We would contribute the data from that study to the i
- 15 date base now being applied to the resolution of severe i
- 16 accident source term technical issues and we would also i c ,
1 l 17 transfer all of that data we will be producing to the other l ! 18 government agencies and in particular, NRC, the nuclear l ) 19 industry and where possible to the public. i 20 CHAIRMAN PALLADINot How are the results of your R&D
- 21 efforts provided to the NRC7 Are they just in the form of a 22 report?
f f 23 MR. McPHERSON: That is correct, sir. In addition, l 24 you are represented on the accident evaluation assessment, our ; 4 25 advisory committee, pardon me, and thereby receive those i i
12 1 results first hand. We do take part'in meetings together 2 where the results are discussed. 3 We have an annual meeting where NRC staffers show up
- 4 and participate. In general, however, we issue what are known 5 as "GEND" reports where the "N" in the GEND refers to NRC and
, 6 the "D" is DOE. So these reports are reviewed by all sides.
7 The "G" is GPU and the "E" is EPRI. i 8 CHAIRMAN PALLADINO: All right. Thank you. 9 MR. McPHERSON: As the program evolves, you may 10 participate in different ways but that is the way that we have 11 been operating to date. i 12' (Slide.)
- 4 i 13 MR. McPHERSON: I would like to first discuss the J
14 accident scenario. I ! 15 CHAIRMAN PALLADINO: Just one other follow-up, how 16 about the nuclear industry? Do they get the information 17 through reports primarily? I 1 18 MR. McPHERSON: Yes, sir. i 19 CHAIRMAN PALLADINO: All right. ; 4 20 MR. McPHERSON: Again though, they are represented i 21 on the advisory committee. l 22 l
- CHAIRMAN PALLADINO
- All right.
23 MR. McPHERSON: The accident scenario that I will be i 24 presenting is as interpreted by the known conditions of the f f
- 25 core, from the SCDAP analysis which we have been doing where L
13 1 SCDAP is the NRC code which stands for Severe Core Damage 2 Analysis Program and the other information comes from the 3 on-line instrumentation as it is being interpreted and 4 re-interpreted from the time it was originally recorded back 5 at the time of the accident. 6 That is turning out to be a very significant source 7 of new data for us. 8 (Slide.] 9 MR. McPHERSON: Let me begin then with the known 10 core conditions. I will start at the top on this slide and we 11 will go down from the top. 12 The leadscrews have been found to have been at . 13 maximum temperatures of 755 K at the top to as high as 1255 K 14 at the bottom of the upper plenum just above the core. 15 The other leadscrews which are not shown in this 16 diagram have lower temperatures going out to the periphery. 17 Clearly, they have all been at extremely high temperatures. 18 , Just below the upper plenum, we see a 30 percent 19 void in the core and at the top of the upper plenum, there are 20 localized regions of oxidized and molten stainless steel. I 21 will show you photographs of these subsequently. 22 At the top of the existing core now, there is a 23 debris which contains prior molten fuel. Therefore, it has 24 reached 3100 K and there is fully oxidized zircaloy. There is 25 some unrestructured fuel to be found.
14 1 Below that, there is a hard layer of about 1.60 to 2 1.75 meters thick. 3 CHAIT. MAN PALLADINO: Excuse me. I tend to think in 4 Fahrenheit. Is 3100 K above 5,000 degree Fahrenheit? 5 MR. McPHERSON: Yes, sir, it is. 6 CHAIRMAN PALLADINO: Thank you. 7 MR. McPHERSON: I apologize. All of our 8 temperatures are going to be reported in Kelvin but perhaps I 9 could give you some assistance as we go along. 10 CHAIRMAN PALLADINO: I notice later you are going to 11 give us Mega Pascals per unit area and I am going to have to 12 get that translated to PSI. 13 MR. McPHERSON: We will manage with that. 14 COMMISSIONER BERNTHAL: Just multiply by nina 15 fifths, Joe, and you will be okay. 16 MR. McPHERSON: As I say, there is some 17 unrestructured fuel but in the main, it is in the form of la cinders and previously molten oxides. 19 Then there is the hard layer which is above the 20 unknown portion in the core and we will be talking a little 21 bit about that later, what we think is in there. 22 Below is the core support assembly which to all 23 observations has undergone no damage that we can see. In 24 particular, the bolts around the assembly holding the whole 25 thing together appear completely undamaged.
l 15 1 Then below that core support assembly is from ten to 2 20-percent of the original core laying in the lower plenum. 3 There are thermocouples coming up through the bottom of the 4 lower plenum which have had their junctions reformed at that 5 point indicating that they have seen extremely high 6 temperatures. Clearly they have if the core is down there or 7 part of the core is down there. 8 Before moving on, let me say that we will first look 9 at the bottom of the upper plenum. We will be looking up at 10 that and then we will look down at the top of the debris bed 11 on top of the core. 12 I would like to recall that the upper plenum has 13 been removed. Consequently, the standing fuel bundles which 14 were in the periphery of the bundle have now fallen over on 1
- 15 top of that debris and create a further debris bed of rather i 16 jackstraw appearance.
17 So when we look down, we will be seeing that rather 18 than the original debris that was seen. 19 We are then going to sneak down a television camera 20 to the lower plenum where we will see the debris in the lower 21 plenum from various views and I will show you what those views 22 are before showing the photographs and then look up through 23 holes in the lower plate, the flow distributor, the very 24 bottom plate and look at some debris up inside the core 25 support structure, the assembly there. We will see what is to ,
3 16 j 1 be seen down there. 2 COMMISSIONER ASSELSTINE: Don, do you have an 3 estimate for how much of the core actually melted in terms of i 4 the fuel itself? 5 CHAIRMAN PALLADINO: In terms of fuel? 6 COMMISSIONER ASSELSTINE: Yes. l 7 MR. McPHERSON: There is a variety of ways of !
; 8 answering that question, commissioner Asselstine, and let me '
i i 9 first say that we know for certain that there has been some 10 molten UO-2 meaning we have hit those top temperatures but , I 11 there is a mixture of UO-2 and zirconium dioxide and a mixture 12 of those two in solution which could be anywhere which means 1 13 that the temperatures which they reached could be anywhere I l 14 from about 2000 K up to the 3100 K. , j 15 So if your question is how much of the core was ! l l 16 molten, then my estimate personally from what I have seen is ( s 17 70-percent but that is my own personal estimate having looked i 18 at what I have seen. GPU has not said that nor has EG&G. i l 19 CHAIRMAN PALLADINot I am sorry, do you mean , I 20 / 70-percent fuel? i i 21 MR. McPHERSON: Of the entire core. j 22 CHAIRMAN PALLADINot of the entire core. I j 23 MR. McPHERSON: Yes. 24 CHAIRMAN PALLADINO! Do I conclude that means \, ! 25 70-percent of the fuel? 1
4 17 1 MR. McPHERSON: Yes, sir. I don't mean that 2 70-percent reached 3100 K, a smaller percentage, perhaps and i 3 let me just guess, five to ten percent of the fuel reached l
; 4 that temperature.
1 5 We have some confusion in this question of amount of ! j 6 melting because of the various temperatures at which the 7 different metals and oxides melt. We begin by the control rod ' i :
- 8 materials melting below 1500 K and failing at about 1500 K so l l
! 9 that they become liquid and are candling down before anything l ;10 else is. !
l ! 11 Then the zirconium starts to melt at about 1720 K i i j 12 and then the -- I am sorry, the stainless steel.c does at 1720, '
)
)i 13 then the zirconium beta phase melts at 1950 K, the alpha phase 4
! 14 melts at 2150 K and both of those zirconia are capable then of ! ! I j 15 dissolving U0-2. So you have a new mix coming into play and I 16 as the temperature goes up to 2650, the zircaloy forms a ; 17 monotectic which is capable of absorbing all of the Uo-2 in !
t ] 18 the core if it were all molten, if the aircaloy were all j 19 molten. I
, 20 But it is oxidizing meanwhile and then you get up i
l 21 to the question of when does the zirconium dioxide melt and t j 22 that comes in at 2950 and then we have, of course, the Uo-2 23 melting at 3150. [ 24 sc with that naze of different materials melting at 4 j 25 different points it is a difficult question to answer very i ' 1 1 I
18 1 directly. 2 COMMISSIONER ASSELSTINE: Thank you. 3 (Slide.] 4 MR. McPHERSON: In the next slide we have a color 5 legend indicating the amount of damage that has been observed 6 in the lower surface of the upper plenum. 7 You will see a very asymmetric design or pattern of 8 this damage. You will see that there are a few areas of 9 extrema deformation and then some areas, the pink areas, a 10 foamy surface of stainless steel. That means that it has been 11 oxidized by steam so a high temperature of steam has passed 12 over those areas. 13 Next, there is a damaged area in yellow but which is 14 not foamy. This has been damaged then by high temperature gas 15 but with not much oxygen in it. So it is probably not steam 16 and it is probably high temperature hydrogen. 17 There are slightly damaged areas and then areas not 18 affected at all. Se they have not seen temperatures above 19 1700 in those undamaged areas. 20 This implies a geometry of core damage and of flow 21 of coolant or steam or hydrogen out of those damaged areas 22 which is very asymmetrical and this leads us to believe that 23 there is an interesting structure within the damaged area 24 below which needs to be understood. 25 That will be one of the objectives of our program to
19 1 determine why we have that damage pattern. 2 (slide.) i 3 MR. McPHERSON: My next two sides are in fact i 4 photographs of that same structure we have just been j 5 discussing.- l ) 6 CHAIRMAN PALLADINO: You say this is very asymmetric [ 7 and yet I can see a certain amount of symmetry relative to the s l 8 loop outlets. I will agree that it is not perfectly symmetric ' a t 1 9 but it is split right down the middle it seems like. i i i 10 MR. McPHERSON: Yes. I was referring in a way to ) i 11 the fact that what you would expect under these conditions is l ~ 12 the hottest area to be in the center and the cooler areas
' l t
^ 13 toward the periphery and here we see the hottest areas of L s 14 skewed around. If you look at the white, they are just in l
- 15 very isolated locations. '
4 16 CHAIRMAN PALLADINot Yes, I see. 17 MR. McPHERSON: The pink area is skewed around to J i
; 18 the right on the right and then sort of spotty on the left.
19 There is an implication that there were certain flow 20 streamings of the high temperature hydrogen, for example, 21 coming up here. I i 1 22 CHAIRMAN PALLADINot All right. l l 23 MR. McPHERSON: It is no doubt related to the way in I { 24 which the core relocated and a crust formed and allowed the 25 gases to flow through it. l l
20 1 If we now look up at the actual photographs of this 2 area we see rods of zircaloy and control rod guide tubes. 3 CHAIRMAN PALIADINO: Are we icoking down on the 4 upper grid? ' 5 MR. McPHERSON: We are looking up on it. 6 CHAIRMAN PALLADINO: Oh, we are looking up. 7 MR. McPHERSON: From Within the void and looking up 8 en the upper grid. - 9 MR. VAUGHANt A camara in the void looking upward. 10 CHAIRMAN PALLADINO: All right. ; 11 MR. McFHERSON: So many of these rods, of courno, 12 have boon destroyed and in one way or another fallen off and 13 there is a highly exid'ized zircaloy rod on the right that once 14 was a fual rod end you see no fuel exists inside. It has 15 clearly fallen out one way or the other. 16 (Slide.] 17 MR. McPHERSON: In the next vievgraph, we soo some 18 photographo of lugs. These are thick steel slabs which are 19 part of the upper plenum which lower down between each fuel 20 element to pcoition it an.' these lugs, you will see here in 21 this caso, have been melted away with not much oxidation 22 because there is not much foaming or going to the next photo, 23 thay have been foamed away or oxidized ar.d as n result produco ' 24 this foamy structure. 25 (slide.] i
l 81 1 MR. McFHERSON: In the following photograph, we ses 2 a lug which has been ablated by the flow of high toinparature 3 high velocity gaa. Very likely hydrogen has passed by and 4 carried away the melted steel as it was passing by. 5 6 7 8 9 10 ' 11 12 13 14 15 16 17 la 19 20 21 22 23 24 25
' j I
22 j 1 (Glide.) 2 MR. McPIIERSCU; Now I an going to divert our 3 discussion a little bit at this point, because it is pertinent 4 to point out that we have in the LOFT -- from the last LOFT 5 experiment, have a fuel bundle that was damaged almost to the 6 eano degree, and if you look at the -- if you recall what we - 7 just saw with *, hose rods hanging down, . burnt off, broken of f, 8 and some of the debrio that you saw, this next photograph in a 9 picture of the slot, looking into the very top of the fuci 10 bundle, which was put through a cevore fuel damage accident in 11 the finsi experiment in LOFT. 12 The debris that you see sitting on this little ledqa t 13 right at the top of hha fuel has been identified as foamed 14 stainless stool, oilver nugguts which came out cf the control 15 red matorialo which wore inside that bundle, and in one case 1G -- you won't sae it here -- a fuel pollet has been choorved. 17 Control rods can he scen looking into this, and 18 perhaps you'll see them a little on thn next photograph. 19 (Slide.] 20 And they have been equally dama.yed, very similar to 21 What we have seen in the TMI case. 22 CHAIRMAN PALLADINO: Now what am I looking at here? 23 MR. McPHERSON: 'lcu're 1 coking through a horizontal 24 slet at tho very top of a fuel bundlo, and hanging down ' 25 inside, there aro control roda which you can oes the light
, t 23 i 1 surface there that Jim is pointing cut, f i
2 CRAIRMAN PALLADINO: Oh, I see. , 3 MR. McPHER30Nt Some of those are eaten away, burned l 4 away, fallen ofi'. It's the very name structure, essentially, 5 as we have seen at the top of the core in T11I. 6 How in the case of the LOFT test, no materials came > l 7 out the bottom. as you recall, there were gaterialc that fell ! 8 or flowed out through the bottom, from the bottom of the core l 9 in TMI. This means that we have damaged the LOTT bundle to i 10 some intermediary point through the avolution of the TMI ; 11 accident and then fro. Ten it there. And I am very pinased to l 12 say that OECD LOFT Lokrd has just decided to fund the { 13 examination of that bundle, so we will be cutting it up and , t 14 examining it, and have data two or three years down the line ! i 15 trem now wnich will be directly applicabla and appropriate to 5 16 interpolatien of the data between TMI and your PBF program. 17 CHAIRMAN PALLADIUC: What is it? \ fuel element l . , 19 from LC?T that thsy're going to -- ! I 19 MR. McPHERSON That'e correct, sir, yes. t 20 CCMMISSIONER BEPNTHAL: Where is the funding for 21 this coming from hesides OECD?
- l 22 MR. McPilER3ON: Well, OECD itself does not provido J
23 any funding. The program was formed under their auspices. 24 The funding comes from te.n countries which have signed up, 25 signed an agreement to participate in this program. In the t i t
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n- y--- - - _ , - -
24 1 U.S., these consist of DOE, the NRC, and EPRI, and at this , 2 time we are hav.ing discussions with the NRC on what the share 3 of the U.S. contribution will be. 4 MR. VAUGHAN: You will remember, Mr. Chairman, of 5 course, that the significance of this is that the LOFT bundle 6 was highly instrumented on purpose to try to repeat the 7 conditions, whereas the THI-2 situation, of course, was not. 8 MR. McPHERSON: This is that highly instrumented 9 test that you were looking for, Mr. Chairman, in the last 10 meeting on TMI, when you were referring in the last meeting 11 with GPU that there should have been more -- a better 12 instrumented, and while we have an experiment which is very , 13 similar, but which was instrumented. 14 I'll go on now to one last look down at the top of 15 the core. 16 [ Slide.) 17 And you'll see this -- 18 CHAIRMAN PALLADINO: Now are we looking on the top 19 of the core? 20 MR. McPHERSON: Back to TMI. 21 CHAIKEAN PALLADINO: And not on the grid. 22 MR. McPHERSON: No. We're looking -- no, we've 23 turned our sights downwards. You'll see some lights lighting 24 up this jackstrawed configuration of rod stube lying on top of 25 the earlier debris that we say.
25 1 COMMISSIONER ASSELSTINE: This is after the upper 2 plenum has been removed? 3 MR. McPHERSON: Yes, sir, that's correct. 4 CHAIRMAN PALLADINO: What are those dark spots 5 again? 6 MR. McPHERSON: Those are dirt. The ones on the 7 right in the pattern of three, those are simply dirt on the 8 camera lens. The two dark spots in the light are simply the 9 lights. The light below is shadowing them. 10 There's a canister on the left into which the 11 damaged fuel is being placed. There is an and fitting above 12 the left light. It's a square irrangement there. And for 13 those of you looking at our dirty laundry, why we have a chem 14 wipe lying on top of the core there. 15 CHAIRMAN PALLADINO: A what? 16 MR. McPHERSON: A chem wipe. 17 COMMISSIONER BERNTHAL: It's amazing that made it 18 through the accident. 19 (Laughter.] 20 [ Slide.] El MR. McPHERSON: I haven't told you about all the 22 screwdrivers and nuts and bolts in there. 23 We'll go under the lower head debris now. Before 24 showing you the photographs, it's useful to look at a rather 25 complicated diagram which will help me explain where we're
26 1 going to be seeing photographs in the next slides. 2 To begin with, there is a flange right around this 3 diagram containing holes through which cameras, lighting, and 4 sample-grabbers were lowered. 5 CHAIRMAN PALLADINO: I'm sorry. I missed that. You 6 say that's a -- is that an annulus? 7 MR. McPHERSON: Yes. 8 CHAIRMAN PALLADINO: You said a flange. 9 MR. McPHERSON: I'm sorry. It's a flange, and there 10 are holes in that flange. 11 CHAIRMAN PALLADINO: Oh, I see. 12 MR. McPHERSON: This is actually the flange that 13 separates the downcomer from the upper plenum, the hot from 14 cold leg areas. And these cameras, lighting, and 15 sample-grabbers were lowered down through those tiny holes in 16 that flange. 17 The shaded area in your handout is the area which 18 was first observed up until June of '85, and that's the darker 19 blue. And then the lighter blue areas or those areas in your 20 handout which are circumscribed by a very heavy line are the 21 areas which have been viewed subsequently up to December of 22 '85. 23 The grid that's overlaid within the circle simply 24 shows the pattern of fuel bundles, and the dark spots on many 25 of the squares in that grid are the locations of instrument
l 27 1 guide tubes which come up through the upper plenum. There are 2 52 of these, so there is considerable information to be gained 3 from the instruments and information to be learned from the 4 interaction of the fuel which fell through into the lower 5 plenum and interacted with those. 6 CHAIRMAN PALLADINO: Was there water in the lower 7 plenum, do you expect, when that dropped in? 8 MR. McPHERSON: Yes, sir. Yes, I will show you ; 9 later what information we have to lead us to that conclusion. 10 Now there is a red line on the photograph and a 11 lighter line in your handout which indicates the boundary that
- 12 we understand the debris forms at this time in the lower 13 plenum -- that is, beyond that boundary, there's simply a 14 clean surface of lower plenum or the inner liner of the --
15 CHAIRMAN PALLADINO: Now which line is it again? 16 MR. McPHERSON: In your handout, it's the thinner , 17 line with some dots in it and with some dashes in it. The 18 dashes indicate an area of uncertainty that we haven't seen. 19 The small dots, which Jim is pointing to -- it's a red line on 20 the photograph -- is a cliff of this debris material from four 21 to twelve inches high. 22 CHAIRMAN PALLADINO: Now you're saying, it was clean 23 outside this -- I'll call it circle; it isn't a circle, but -- l 24 MR. McPHERSON: Yes, sir, that's correct. 25 CHAIRMAN PALLADINO: But what are these dark --
. l 28 1 MR. McPHERSON: The dark? The dashed grey --
2 CHAIRMAN PALLADINO: The grey spots on our 3 handouts. Some of those are outside the circle. 4 MR. McPHERSON: Those are the areas we have been 5 able to visually see, to see with our cameras. 6 COMMISSIONER ASSELSTINE: Those are just the areas
- 7 that you looked at.
8 MR. McPHERSON: Yes, up until June. And the other 9 areas in the larger area, we have looked at up to December. 10 Now before you turn your page, we are going to see 11 photographs first of an instrument penetration at the 2-L 12 level, the 2-L point, that instrument penetration. 13 CHAIRMAN PALLADINO: 2-L? Oh, I see. 14 MR. McPHERSON: And then we're going to look along 15 Row 13 and see three of these instruments which are outside 4 16 the boundary of the debris, followed by one that is 17 encompassed by the debris. 18 Now we'll go on to those photographs. 19 [ Slide.) - 20 CHAIRMAN PALLADINO: Now are we looking down, or are 21 we looking up? We're looking down? 22 MR. McPHERSON: We're looking downwards, yes. And ! 23 the first one on your handout is the one at the top of the 24 page. l l 25 We are looking down, then, at the debris coming up i l l l
29 1 to the curvature of the lower plenum. 2 CHAIRMAN PALLADINO: Is this in the 13th row area? 3 MR. McPHERSON: Yes. That's the 2-L row. 4 CHAIRMAN PALLADINO: 2-L? 5 MR. McPHERSON: Yes. j 6 CHAIRMAN PALLADINO: Oh, that's not 13. 7 MR. McPHERSON: The first one is 2-L. The 8 subsequent ones are all 13's. 9 But this was to show you first an example of the 10 horizontal layering of the debris. And I will say something 11 about dimensions here first. 12 The instrument guida tube rising up to the left, at 13 the left corner, has a'4.5-inch diameter with the penetration 14 nozzle below it, 1.75-inch, just to give you an idea of the 15 sizes of the debris. 16 The nature of that debris we have found to date is, 17 it's prior molten. It is a ceramic; it is brittle, porous, 18 and it is homogeneous. Generally these are of the same nature 19 as the debris seen -- that has been taken as a sample out of 20 the upper part of the core, with one exception, that that ! 21 debris is non-homcgeneous 22 CHAIRMAN PALLADINO: Is what? 23 MR. McPHERSON: It's heterogeneous. 24 COMMISSIONER BERNTHAL: It's ceramic, meaning its 25 zirc oxide primarily. 1
, _ . , , . . _ , _ . , . - - - . - . , - - , . , , - - . . , ~ - , , _ , - ,,-.,,,,,,,,,,,_..___,_,..,_w- -
_ ,-.,_.e -
30 1 MR. McPHERSON: Zirc oxide, UO-2. , 2 COMMISSIONER BERNTHAL: What else? 3 MR. McPHERSON: And UO-2. 4 There are also some indications of nickel, chrome, 5 and ferrous oxides, meaning some steel is involved that has 6 been melted down here, and that steel could have come from the 7 grids or the upper structures. 8 There is about a 20 percent retention of iodine and 9 cesium, which is surprising to us in that these are highly 10 volatile, and one would have expected them to have been driven i 11 off, but they've been retained, 20 percent. It was 30 percent 12 in the debris taken from the core. 13 COMMISSIONER BERNTHAL: Is that retention also 14 homogeneous retention throughout the rubble material? 15 MR. McPHERSON: In the lower plenum, yes. 16 Everything is quite homogeneous down there. 17 COMMISSIONER BERNTHAL: Have you got any suggestions 18 for mechanism there? 19 MR. McPHERSON: I defer to my expert here. Any 20 suggestions for a mechanism, Jim? l l 21 MR. BROUGHTON: No, at this point in time, we don't 22 have any real suggestion. We were surprised, quite surprised, 23 that the retention was that high in materials that have been 24 to in excess of 2800 Kelvin. I 25 COMMISSIONER BERNTHAL: It really has to be almost a l
, 31 1
1 high-temperature absorption or something, doesn't it? 2 MR. BROUGHTON: One of the suggestions is that it 3 might be a silicate, cesium silicate, formed as the materials 4 flowed through the core aupport assembly. Cesium silicates 5 are relatively involatile. 6 COMMISSIONER BERNTHAL: Cesium is easier to 7 understand, but the iodine is -- 8 MR. BROUGHTON: The iodine, we don't understand 9 yet. That's one of the measurement objectives, is to find out 10 what chemical form it is and why it was retained. 11 COMMISSIONER BERNTHAL: I guess unless the cesium -- 12 unless it was carried in cesium iodide somehow and the 13 silicate forms, and the iodine is left homogeneously, then, 14 throughout the material. ! 15 MR. BROUGHTON: But that's not consistent with the 16 percentages. We're seeing approximately 20 percent cesium and 17 approximately 20 percent iodine. Remember that the ratios of 18 cesium to iodine are approximately 1 in 8 or 1 in 10. 19 CHAIRMAN PALLADINO: Cesium to iodine? 20 MR. BROUGHTON: Cesium to iodine. There is eight to 21 ten times more cesium than iodine. 22 CHAIRMAN PALLADINO: Oh, I see. l 23 MR. BROUGHTON: So 20 percent cesium and 20 percent i 24 iodine still gives you that same ratio of 1 in 8 or 1 in 10. 25 So it's not consistent that one would have -- i
32 1 COMMISSIONER BERNTHAL: Sorry. I'm missing ) I 2 something here. ; 3 CHAIRMAN PALLADINO: I missed it too. 4 COMMISSIONER SERNTHAL: It's 1 to 1 atom percent, or 5 what are you talking about here? 6 MR. BROUGHTON: No. In a normal reactor in a normal
*/ core, the ratio is one atom of iodine to eight atoms of 8 cesium.
9 COMMISSIONER BERNTHAL: But you're saying it's 1 to 10 1 here. 11 MR. BROUGHTON: No. I'm saying that the percent 12 retention is about the same, 20 percent. 13 COMMISSIONER BERNTHAL: Oh, I see. I se'a, okay. 14 CHAIRMAN PALLADINO: So they keep the ratio. 15 MR. BROUGHTON: The ratio stays approximately the 16 same. So what the bottom line is, we don't at this point in 17 time really understand why the high volatiles are retained to 18 this extent. 19 MR. McPHERSON: One other point that you might want 20 to pursue with Jim is we have also noted that the noble 21 metals, the retention of the noble metals down here, which you 22 would expect to find closer to 100 percent, is less than 10 23 percent. 24 CHAIRMAN PALLADINO: What do you mean, noble metal? 25 MR. McPHERSON: The antimony, ruthenium and
O 33 1 molybdenum. We have not found those metals outside the 2 containment vessel, however, so we expect -- again, theorize 3 -- that they have gone with other metals, have relocated 4 themselves, associated with the steel, for example. 4 5 [ Slide.] 6 I will move on now to the next photograph, which 7 goes around to that row 13 and shows the wall of debris. That 8 is simply looking in from the top of that diagram we were 9 looking at before, where we saw a cliff of the debris 10 material. That cliff is visible in this photograph. 11 (Slide.] 12 And we just turn a little to the right by looking at, 13 the next photograph, and we can see a penetration here which 14 indicates, our experts say, that the weld of the penetration 15 through the reactor vessel is in excellent shape. It looks 16 like a new weld, as far as the experts are concerned. 17 COMMISSIONER BERNTHAL: This is now 86-72-3, No. 6? 18 MR. McPHERSON: That's correct, yes.
- 19 CHAIRMAN PALLADINO
- Where is the weld?
20 COMMISSIONER BERNTHAL: If you can tell that's an 21 excellent weld, you have better eyesight than I do. 22 MR. McPHERSON: That's what I said, too. ] 23 CHAIRMAN PALLADINO: What is that thing that seems 24 to be going up to the right? 25 MR. McPHERSON: That is the penetration nozzle of an
34 1 instrument. 2 CHAIRMAN PALLADINO: I see. 3 MR. McPHERSON: And it is the weld that we are 4 concerned with there where that interfaces with the vessel. 5 (Slide.] 6 The next photograph indicates the wall having 7 essentially encompassed an instrument penetration tube. 8 CHAIRMAN PALLADINO: Can I ask you a question? The 9 penetration, you say, is about an inch and three quarters? And 10 what is the 4-inch part above it? 11 MR. McPHERSON: That is a guide tube through which 12 the instruments are allowed to move. It doesn't have any 13 particular importance to us except to indicate that there has 14 been no damage to those that we can see. Even this one which 15 has been wrapped around by the debris does not appear to be 16 damaged. 17 CHAIRMAN PALLADINO: The guide tube. 18 MR. McPHERSON: Yes, sir, the guide tube'and the -- 19 CHAIRMAN PALLADINO: How about that lower tube? I 20 can't tell whether it is damaged or just wrapped around the 21 debris. 22 MR. McPHERSON: Yes. Our information from the 23 experts is they cannot see any damage. Of course, we have got 24 to remove that debris and look in behind eventually, but from 25 the visible side there is no damage. l
35 1 [ Slide] 2 We move now to a photograph which simply shows a 3 size of one of the larger pieces of debris. There is a light 4 cord and light handle shown on the lower laft of that 5 photograph. The handle is about four inches long, and the 6 idea here is to show that larger piece of debris must be about 7 6-1/2 inches long by 4 inches wide, perhaps, something which 8 -- 9 CHAIRMAN PALLADINO: How can you tell it's a single 10 piece? 11 MR. McPHERSON: Well, it looks a single piece, I 12 guess, is all I could say. Any other evidence that it's a 13 single piece, Jim? i 14 MR. VAUGHAN: I think what you are seeing is the 15 lighting highlights on the irregular surface on the second 16 piece, kind of like a chunk of a rock. 17 MR. McPHERSON: They do move the light around-so 18 that while they are looking at it they get an idea. 19 [ Slide.] 2 '- In the next photograph we are now looking up at the 21 diffuser plate, the one through which the flow passes normally 22 up into thr core, and you will see some debris hanging down 23 out of this hole. We have seen several holes like this with 24 debris hanging from them. We have put the camera up into at 25 least two holes, and we see some debris hanging up on that !
36 a 1 plate, and we are also able to see holes above in the next 2 plate above and see no damage to those holes. 3 Now, the access we have had is very limited, so this 4 is not a generalization, but anything we have seen does not i
- 5 show damage.
6 (Slide.] 7 I am going to go through what we believe to be the
- 8 evolution of the accident following a pressure history. In 9 any kind of experiment or accident where temperatures and 10 pressures are changing, a pressure history is a very 11 meaningful way to follow that. We see a lot of things showing 12 up and see events take place by the changes in the gradient of 13 the pressure, and this in megaPascals we see, and as you were
! 14 pointing out, Mr. Chairman, if one multiplies by 145, you get 15 it in megaPascals into psi, or better still, the 15 16 megaPascals is roughly 2200 pai, the operating pressure of the 17 reactor when the accident was initiated, and the 5 is down 18 around 700, 750 psi. So we are wandering around between 750 19 and 2300. 20 During the first hundred minutes of the accident, as 1 21 you know, the PORV was stuck open and we were continually ' 22 losing inventory from the primary coolant system. The HPIS, l 23 the high pressure injection system, was from time to time 24 turned on and throttled into different degrees, so there was a 25 tiny flow in but a very significant flow out of the primary
)
i
37 1 system from the PORV. 2 At 100 minutes, because of the continuing loss 3 of inventory, the pumps began to vibrate to the point where it 4 was decided they had to be shut down, and of course, at that L 5 time the inventory was that low that when it settled out, the j 6 water separated from the steam, the core was already beginning 7 to uncover. Now we see the pressure continuing to drop 8 because now it is relieved by steam flowing out of the PORV 9 and you can relieve a higher volume flow rate with steam ] 10 rather than two-phase water and steam, so the pressure drops 11 more quickly. l 12 At about 110 minutes, the fuel failures began, and 13 the crew began to pick up indications of released fission 14 products. When we get down to the 130-minute point, a block ; 15 valve wos closed. At that point, of course, it stopped up 16 again, and because steam is still being generated in the core, 17 the pressure began to rise. 18 We wore into significant zircalloy oxidation at that 19 point, and at about 160 minutes, that was' exacerbated as the 20 zircalloy reached higher temperatures up at the point where it i 21 starts to really burn. The temperature rise increases 22 dramatically at that point. As Jim has pointed out, I'm sure 1 l 23 it's burning up. And at a point right where Jim will indicate 24 there, the B pump was turned on. 25 Now, it was turned on for five minutes, but there I
38 1 was only water in that pump sufficient to provide a few 2 seconds of flow. As that flow passed up through the core,
- 3 considerable amount of vapor was generated, and that caused 4 the higher rise rate in pressure. But since there was just a 5 flash of water passing through, the rise rate dropped again,
! 6 and you see it peaked out up at the top and returned to the 7 same rise rate as we had way back before the zircalloy started ' 8 to burn. i 9 At the very top pressure point, the block valve was 10 reopened, and of course, that dropped the pressure and it 11 continued to drop and the HPIS was brought on, which even i i 12 dropped it further because that is cold water dropping into l ! 13 hot steam. It condensas'the steam and the pressure drops more 14 quickly. 15 Down at the bottom of that slope, the block valve 16 was closed -- Jim has got it. The block valve was closed, so , , t 17 you see the pressure rise again at the same earlier rate. 18 Then we believe the core relocated to the lower plenum. In 19 other words, a slurry of the core mixture flowed down from 20 within the core into the lower plenum through the holes in 1 ! 21 that core support structure that we saw earlier. 22 That, of course, generated steam, which caused the l 23 pressure to rise by approximately 1.5 megaPascals, 200 to 250 l 1 24 psi. And then that died away again because the slurry of i 25 molten fuel would by then have been surraunded in a vapor l I l
. - . _ _ - . .... , _ - - - - - - - - - - - - - - .- -. - - - - - - - ~ ~ - ~ - - - - ~ ~ - - - ~ - - -
39 1 layer, which does not generate much steam. It is.just a vapor 2 layer sitting quietly in the bottom of the lower plenum and 3 slowly cooling off. 4 In fact, as I will point out later, that cool-off 5 period occurred over a period of many tens of hours. 6 CHAIRMAN PALLADINO: Did you say earlier there was 7 water in the bottom plenum? ' 8 MR. McPHERSON: Yes, sir. 9 CHAIRMAN PALLADINO: How far up? 10 MR. McPHERSON: At the time this relocated, we 11 believe the core was essentially covered. The core material 12 was covered. 13 CHAIRMAN PALLADINO: When? 14 MR. McPHERSON: At 227 minutes. It is not marked on 15 there, but where the arrow points to core relocation, that, i 16 fact, is the 227-minute mark. 17 COMMISSIONER ASSELSTINE: So the melting really 18 occurred between 7 and 8 o' clock. 19 CHAIRMAN PALLADINO: Between what? 20 COMMISSIONER ASSELSTINE: Between 7 and 8 o' clock. 21 MR. McPHERSON: That melting, yes, sir. 22 COMMISSIONER BERNTHAL: That occurred at that point, 23 though, because you had a large mass that could not be 24 effectively cooled even though the vessel was full, 25 essentially.
, 40 1 MR. McPHERSON: That is correct. I will come back 2 to that.
3 This is sort of the end of what we know. Now I will 4 get into what we think happened through that sequence again. 1 i 5 I know you have heard some of this before from GPU, and I 6 apologize for repeating, but I know it is helpful to have 4 i 7 these things repeated. 8 COMMISSIONER BERNTHAL: I guess Commissioner 1 j 9 Asselstine has heard some of this for about the six hundredth i l 10 time, but it is quite all right. 11 MR. McPHERSON: He clearly enjoys it, I can see. 12 COMMISSIONER ASSELSTINE: There are new interesting l 13 wrinkles every time. j 14 CHAIRMAN PALLADINO: Some of us need refreshers 15 anyhow. 16 COMMISSIONER BERNTHAL: We do learn more, though, as
- 17 we go along. L i
i 18 COMMISSIONER ASSELSTINE: That's right. i l 19 MR. McPHERSON: One last piece of evidence is shown 20 in this next slide. l 21 [ Slide.] 22 There is a grid overview here, but in fact what we 23 are showing'is the temperatures which are actually measured in 24 the lower plenum. Within that shaded area, we have found that 25 all of the thermocouples which came up through the instrument
. 41 1 penetration nozzles have rejunctioned, that is, formed a new 2 hot junction down where they were melted, or saw high 3 temperatures. In fact, around about 2200 K, a thermocouple 4 will typically rejunction. These thermocouples do. And all of 5 these rejunctions are inside that area and they all show these 6 temperatures which are very high -- and incidentally, they 7 showed them at a time beyond the 227-minute point.
8 CHAIRMAN PALLADINO: Did I hear you right? Did you o say that it forms a new junction at 2200? JO MR. McPHERSON: Yes, sir. 11 CHAIRMAN PALLADINO: Well, these temperatures seem 12 lower than 2200. 13 MR. McPHERSON: Yes, sir. 14 CHAIRMAN PALLADINO: So what are they telling us? l 15 MR. McPHERSON: What we are telling us is that the , 16 fuel flowed down into the lower plenum and caused new 17 junctions to form down there, and subsequent to that l 18 reformation, these are temperatures which they then read. 19 MR. VAUGHAN: That means it is functioning again. 20 MR. McPHERSON: They are refunctioning. 21 COMMISSIONER BERNTHAL: Was that unexpected at all? 22 I guess I asked the same question of INEL. I can't remember 23 what they told me. These things really can melt and then cool 24 back down and give accurate temperature readings after 25 reforming? l l l
i .
. 42 1 MR. McPHERSON: Yes, sir.
2 COMMISSIONER BERNTHAL: Was that unexpected? 3 MR. McPHERSON: No. 4 COMMISSIONER BERNTHAL: It was not unexpected. 5 MR. McPHERSON: I can't say at the time of the 6 accident whether -- I don't think they were expecting anything 7 of this nature. But in all of the severe fuel damage work i 8 that we have been doing in PBF, for example, and in the LOFT 3 9 program, rejunctioning is a standard practice. l 10 CHAIRMAN PALLADINO: You used the word " accurate." 11 Are they accurate? You didn't have any calibration, did you? 12 MR. McPHERSON: They are relatively accurate. Do 13 you have a comment on that, Jim? 3 14 MR. BROUGHTON: We found in the PBF test that the 15 now junctions formed during the high temperature portion 16 of the tests, then when the tests are terminated and the 17 bundles are reflooded, the new junctions will measure very ! 18 closely the temperature of the water that comes in and 19 saturation temperature. And it is nearly as accurate as a 1 20 calibrated thermocouple. 21 CHAIRMAN PALLADINO: We are not going to melt cores l 22 to get good thermal couples. Okay. Go on. 23 (Slide.] 24 MR. McPHERSON: We will move now to what we 25 understand as the scenario. We will start at the 174 minute
. l
. l 43 1 point, and that is because the pumps were turned on at 175.
2 THe idea here is this was just before the pump was turned on. 3 At this point, we believe the coolant level was at 4 about two feet above the bottom of the core. 5 CHAIRMAN PALLADINO: I'm sorry. What point in time 6 are we looking at? 7 MR. McPHERSON: 174 minutes. It is in the heading. 8 The liquid level at that point in the core is about 9 two feet. We are quite certain of that because the self 10 powered neutron detectors of which there are hundreds in this 11 core, but at any given layer, there are 52, any given level, 12 and at the lowest level, those self powered neutron detectors 13 had not alarmed. We know those alarm -- there are a couple of 14 alarm points, which we have discovered since the accident and 15 gone back and have been able to interpret the accident on that 16 basis. I 17 Based upon that information, I will just briefly say 18 that we know that this level was covered at the one foot, one 19 and a half foot level. We assume then that the level was 20 approximately two feet. 21 Below that, we still have intact fuel rod stubs. Of 22 course, at the top of the core, we have highly oxidized rod 23 like geometry and intermediate to that, we have had the 24 melting going on of the control rod materials, then the 25 zircaloy, and then the liquifaction of the UO2 from the
-----.-,-,7 - . . . - - - -- - - - .
- _, , - . - . - - - - , , n-- -..n
44 1 zircaloy which has all been falling down to the liquid level, 2 forming a solidified crust at that liquid level, and building 3 up a rather solid mass of a mix of the core materials. 4 Once again, our SPND's and our intermediate and 5 source range detectors corroborate this fuel movement. This 6 comes from looking back at the data that was recorded at the 7 time. 8 [ Slide.] 9 MR. McPHERSON: We move to the point when the pump 10 , was turned on. of course, the highly oxidized zirc is 11 immediately shattered by the water passing up through it. 12 Starting at the top, we have still some oxidized rod stubs 13 right at the top. We have a debris bad now of oxidized and 14 previously molten fuel rod materials which have fallen down on 15 top of that building crust that started near the bottom. 16 Within that, is relocated and partially solidified 17 core material, which will continue now to heat up, even.though 18 it is covered with water. 19 We have performed calculations to confirm that such 20 a mass cannot be cooled by surrounding water. 21 CHAIRMAN PALLADINO: It apparently wasn't porous so
- 22 that the water could get up in between?
23 MR. McPHERSON: Not sufficiently porous. If it 24 were, it would be that hqt that above the frost point, it 25 would be blocked by a vapor that would form quickly.
, _ -~ _ _ - -
. _ _ _ - - _ _ - _ . = . - _ - - _-.
45 1 COMMISSIONER ASSELSTINE: The water just couldn't 2 get in it? 3 MR. McPHERSON: That's right; yes. t 4 As that heated up, of course, it grew in magnitude 5 as far as the liquified portion was concerned and either 6 melted itself through the crust or dissolved itself through 7 any UO2 that was in that lower part of the crust. That will 4 8 only be known after we obtain samples from that area. 9 [ Slide.) 10 MR. McPHERSON: Moving on, we have what we believe 11 to be the end state conditions. Beginning at the top then, we 12 still have the oxidized rod stubs, the core void region, the , 13 debris bed, the crust surrounding in there, the volume which 14 once was liquid and which has eaten itself into the lower 15 planum. The state of the core support assembly, however, is 16 unknown. While it is shown as perhaps somewhat broken up 17 there, we have no evidence that has been broken up. As I 18 nentioned, everything we have seen indicates no damage. 19 COMMISSIONER BERNTHAL: But that's a fascinating , 20 point in itself, because there are two key elements here that 21 prevented this thing, I guess, from being catastrophic. One 22 is the fact that you kept water just above one or more of 23 these plates, I guess. I don't know what the technical term 24 is. 25 CHAIRMAN PALLADINO: Where was the lowest point of l
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---,.,---w .y------.gn-m-- e, - - , - - - . -
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. 46 t l
1 water? ! 2 MR. McPHERSON: About two feet. 3 COMMISSIONER BERNTHAL: It was two feet from the - 4 bottom of the core. For reasons that weren't clear, I guess, ] 5 even to INEL, maybe they are by now, even though the melting 6 point of that steel in the plate is lower than the 5,000 . 7 degrees of some of the core material, stop me if I am wrong
- l 8 here, by whatever the heat transfer mechanism was, obviously I 9 it was pretty good, you still managed to ooze that molten
- 10 material through the plate without very much damage. That is ,
11 a rather surprising thing. ( { 12 MR. McPHERSON: Yes. Just to give you a little more , 13 information on that, recall that pressure rise that we saw at i 1 14 the 227 minute point, that was about 250 psi, let us say, and ; i 1 15 took place over an 18 second period. That would suggest that [ i 16 this relocation, the flow out down through these holes 17 occurred in about that time, 18 seconds. l ! 18 COMMISSIONER ASSELSTINE: Because it dribbled down i i 19 through and then there was enough water there, it cooled by 20 the time it hit the botton? i 21 . MR. McPHERSON: Well, cooled enough that it formed a i 22 cold outer surface, let's say, like pipes in a leva flow, and ^ 23 probably formed scue solid plates which we saw down below and i l t 24 when we looked in the lower plenum, were pushed along as it l 1 l 25 oozed out. ,1 i ! i j
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f ,* 47 I l 1 COMMISSIONER BERNTHAL: It also broke up so that you i . j 2 could get more cooling. l I : 3 MR. McPNERSON: Yes, get more coolant to it. l : i- ; 4 COMMISSIONER BERNTHAL: It rac it through a sieve, i ? a 5 in a crude sense. ? 6 MR. McPRERSON: Yea, which would suggest that unde'r l t j' 7 this circumstance and in any future accident, any hypothesized i
\ ,
! 8 accident, given there is water, given there is a sieve like I L l 9 core support assembly, this kind of thing would normally i j lo happen, as I said, we see no damage to the inner liner of the ; 11 planum, which is stainlese steel, of the lower plenna, and i i j 12 those temperatures we showed you, they were very close to ; t i ,. 13 the neiting point of stainleza steel. J , i 14 There is some corroborating evidence now, recently / 15 produced from the self powered neutron detecters and from the , I i 16 Source range detectors outside the reactor, which have been 17 interpreted to indicate the glow of the core material down to l [ la the icwer plenum at this time, 227 minute point. 19 COMMISSIONER BERNTNAL: The message, and you can ' 20 gall it encouraging if you like, and I guess that is not a !
\
l 21 very good term to use abcut the whole Inciden*:, but the ' 4 22 message that is somewhst sxtraordinary, at taast to me, is how j 23 auch a saving grace is, even a small huount of water that l f 24 remains in the bottom of the vessel. There wasn't an awful l 25 lot left. We had to achieve the purpose of apparently f I . I ! i l .
'_.____ - J
43 1 maintaining those steel support structures barely intact and ; 2 breaking up the molton material as it ran through those 3 support structures. It is really a very key event in the 4 progression of the accident. 4 5 COMMISSIONER ASSELSTINE: Was that due to turning on 6 the pump, providing the water in there? 7 MR. McPHERSON: No. . i 8 COMMISSIONER ASSELSTINE: That was the water that , 9 was in there? 10 MR. McPHERSON: Yes. That pump that was turned on
- 11 only supplied a very small amount. In fact, that is what 12 broke up the upper core to give us the mass we saw later. It 13 is supplying HPIS and feed water.
14 COMMISSIONER BERNTHAL: I was under the impression f 15 that stuff that was oozing through the stainless structure : { 16 there, that was considerably above the melting point of 17 stainless steel. I believe that is what I was told. 18 MR. McPMERSON: Yes. I believe it was, toe. I was 19 referring to the temperatures that were measured in, once it i 1 20 got down there and the hot junctions performed a virtual
- 21 junction down there.
22 MR. VAUGHANt But the water cooling was sufficient i 23 to keep it frem ereding or melting the stainless steel, which j 24 shows the whole thing happened in a flash. 25 { r COMMISSIONER ASSELSTINE: The water was really due j \ l , j _ . - .._~________.__________._.D
l '.' 49 l 1 to the HPI flow, something turned on HPI? 2 MR. McPHERSON: Yes. - l 3 COMMISSIONER ASSELSTINE: If they hadn't turned on 4 HPI, I take it then you would have had the molten blob that 5 hit the botton? : 6 MR. McPHERSON: Yes. Then it is questionable what !' 7 would happen, but certainly it is a new ball game there. 8 COMMISSIONER ASSELSTINE: Exposing the blocked valve 9 and turning on HPI. l 10 MR. VAUGMAN: More precisely to Commissioner : 11 Asselstine's question, do we know that turhing on the high , 12 pressure injection is what put all the water in the bottom or j 13 was some of it there any way? r 14 MR. McPHERSON: I see. ! I 15 MR. VAUGHAN: I think that is the point he is 16 asking. I'm not sure that the HPI flow made up the total i 17 amount that was in the bottom. I think it did not. 18 COMMISSIOUER ASSELSTINE: Yes. 19 MR. McPHERSON: Mr. Vaughan is correct. There was 20 water to begin with and there always was water down there. r l 21 The HPIS was on and off and we still don't know the real i 22 L history of it. 23 MR. BROUGHTON: I would like to add there is 24 evidence that the HPIS was throttled back from its nominal 1 1 25 flow, and what is significant here is with water in the lower ! i l
l . 50 4 1 plenum, a significant fraction of the core relocated into the 1 2 lower planum, formed a coval configuration and the throttle 3 flow from the HPIS maintained that matarial cool until force 4 cooling was re-established ut about 15.5 hours. I think that > 5 is a very significant thing here. j 6 (slide.) 7 MR. McPHERsoIT: I will just give you a summary of 8 the estimated radioisotope distribution in the rsactor. It's s I 9 a rather busy slide. I think after we look at it a bit, 1 10 things will follow, 11 The six locations that we are going to cover in the i 12 plant are indicated on the left. The different radioisotopes 13 are indicated in the table. To begin with, the. fuel and core 14 debris within the vessel still contains a significant amount ) i 15 of krypton, that is calculated in the intact fuel rods, so l 16 that should be there. All other krypton did escape. l 17 However, this cesium and iodine in the 30 percent 1 18 ranges, higher than expected, as we implied before. There has 19 been no tellurium measured. Strontium, 115 percent. What 20 that is indicating is it seems to have concentrated up there 21 in the core debris, whereas ruthenium and cerium -- while 22 cerium is 100 percent, as you expect, ruthenium is low, and wo 23 mentioned that earlier. 24 Going into the vessel internals, the cnly thing that 25 really shows up there is tellurium at two percent of its
l.' 91 1 original inventory. There again, we expect the tellurium to 2 bind up with matals, it nornelly is absorbed onto stainless 3 steel, for example, Primary coolant system, while we see the 4 cesiun and lodine, that is shown up in the primary coolant l 5 and not much else. l 6 In the reacter and auxiliary buildings, the sumps, 7 again, the cesium and iodine show up strongly. They are very 8 soluble and you would expect to find then in the water. 9 Some tollurium and strontius were found there. In the rest of l 10 the reactor and auxiliary buildings and in the reactor 11 building atmosphere, there is vary little "ission products to 12 be found. 13 CHAIRMAN PALLADINO: What form was the iodine for it 14 to be in the auxiliary building sumps? It wouldn't have been 15 gaseous. 16 MR. McPHERSON: No. Casium dioxide, the form now { 17 doesn't indicate how it was releasad, of course. 18 XR. BROUGHTON: The indirect evidence is that the ! 19 iodine was transported as an iodide, probably cesium iodide, 20 but there is no direct evidence for us to confirm that. We i 21 are continuing to evaluate just to try to build a strenger 22 case to show that in fact it was cesium iodide, but it does ' 23 appear to have been transportad as an iodide. 24 COMMISSIONER BERNTHAL: Let me see if I understand. 25 When you say 27, 33 for fuel and core dabris, 45, 41 for the
I . 1
. 52
< 1 reactor and auxiliary building, et cetera, that means those 2 reflect the 8 to .1 fission product ratio, as well? 3 MR. BEOUGHTON; Yes. 4 CCMMISSIONER DERNTHAL: So clearly, it didn't all 5 get transported as cesium iodine. 6 NR. BROUGHTON: The cesium wculd not have been, no. I 7 Cesium hydroxide is very soluble in water and tends to go 8 with the water. 9 COMMISSIONER BERNTRAL: I also understand, and I 10 guess I keep thinking this should add up to 100. Where did 11 the tellurium go? I 12 MR. BROUGHTON: The tellurium, in the measurements 1 13 reflected in this table, tellurium was not measured to any 4 14 appreciable amount, and it is primarily due to at the time we 15 made these measurements, we had not yet developed a technique
.16 to measure or separate the tellurium from the cesium, which 17 tends to mask the tellurium in the sample. We are redoing 18 those measurements now. We have done some measurements on the 19 lower planum debris which indicate that antimony is not 20 retained to a significant amount in the lower plenum, in the 21 debris ws see there.
22 We believe that tellurium and the antimony have 23 preferentially separated and segregated with metallic 24 pressures which we have not yet fcund or examined. 25 COMMISSIONER BERNTHAL: The ruthenium?
53 1 MR. BROUGHTON: The ruthenium, there is evidenc e 2 from George Parker's work at Oak Ridge that ruthenium also 3 will preferentially separate with metallic structures. Again, 4 ve are finding that tellurium has been removed from these high 5 temperature debris and is probably what those metallic 6 struc'tures -- or where we will find the tellurium and the 7 antimony. 8 CHAIRMAN PALLADINO: All right. Are you ready to go 9 on? 10 COMMISSIONER ASSELSTINE: I take it, in terns of the 11 cesium iodide, you have not obtained a lot of informat' ion to 12 let you know for sure one way or the other? 13 MR. BROUGHTON: The direct evidence is no longer 14 available. 15 COMMISSIONER ASSELSTINE: Okay. All right. 16 (Slide.) 17 MR. McPHERSON: Okay. We will move on now to the 18 conclusions that we've taken from the accident scenario. We 19 believe we have a viable and consistent scenario for the 20 accident. We now know sufficient that a scenario will provide 21 a challenging benchmark for savore accident analysis codes and 22 methodologies. 23 TMI-2 results indicate that small-scale severe 24 accident tests such as those at PBF, ACRR, NRU, which they're 25 performing in Canada, and the LOFT experiments most recontly _m , , . . . ,, , , _ . _ _ . . _ - . ___
l .
. 54 l
- 1. can be extrapolated to large plants.
2 CHAIRMAN PALLADINO: All aspects of it? 3 MR. McPHERSON: No, sir. I think the crux of the 4 data that one develops in these small-scale experiments is !i 5 very useful in developing in the codes and understanding the 6 phenomena that we are seeing in TMI, and they will undoubtedly 7 help us to get that whole picture put together in the end. 8 COMMISSIONER ASSELSTINE: What's the basis for that 9 judgment? Was it both the correlation between these and the 10 last LOFT results? 11 MR. McPHERSON: Oh, much more than that, 12 Commissioner Asselstine. 13 I think the PBF results have been most helpful in 14 getting the picture together, what to expect, how fission 15 products interact with one another, what happens in. candling. 16 The whole scenario has been developed in small-scale in pBF, ! 17 and that's helped us all from that point on. 18 Finally, a point that I think both you and i 19 -Commissioner Bernthal were making, the relocation of the 20 molten core into the lower plenum results in a coolable debris [ 21 for accidents such as occurred at TMI-2 with the lower plenum l l 22 full of water. [ i 23 , COMMISSIONER ASSELSTINE: 0,1 your second bullet I i 24 there, do you think that you now have that benchmark in place, f 25 or is still something that you have got to develop? l t I I i
. 55 1 MR. McPHERSON: We're still developing it, but we're 2 getting close, and I will come back to that in a second to 3 tell you where we are in it.
4 (Slide.] 5 This is perhaps a little on the side, but we have 6 been doing an instrumentation and electrical program which is 7 essentially finished, and I knew you wanted to know the - 8 results of all of our R&D, so I've listed them on this one 9 graph, the results of that program. 10 Most of the instrumentation which failed did fail 11 within 24 hours, and it was due generally to moisture
- 12 intrusion. There was no functional damage caused by the
, 13 hydrogen burn which occurred. 14 CHAIRMAN PALLADINO: These are instruments in the 15 containment? 16 MR. McPHERSON: Yes, sir. 17 Tha use of radiation-sensitive transistors in some 18 instruments does cause functional failure. Off-shelf 19 components are less reliable, and recommendations are being 20 developed for standards to apply in containment 21 instrumentation. 22 CHAIRMAN PALLADINO: What do you mean, they are less 23 reliable? You mean they failed sooner than 24 hours? 24 MR. McPHERSON: Yes, sir. Well, they fail sooner 25 than others, let's say. Those which met different standards
+
. 56 1 -- let us say, military standards, for example, military specs 2 -- lasted much longer.
3 There is a report out on that which is in the 4 Staff's hands, so more details are with you. > 5 COMMISSIONER ASSELSTINE: Which instruments or 6 components were designed to, say, military specifications as 7 opposed to a commercial off-the-shelf? - 8 MR. McPHERSON: I can't give you any information on j 4 9 that. 10 COMMISSIONER ASSELSTINE: Okay. But I take it, 11 there were some in the plant. 12 MR. McPHERSON: Yes. 13 COMMISSIONER ASSELSTINE: Okay. , 14 MR. McPHERSON: In-core thermocouples always give 15 useful information, as you've brought out here, in spite of 16 the virtual junction formation above the 2200, and we have 17 developed a circuit diagnostic system for normal maintenance 18 which is now being put to use in some commercial plants at 19 this very time for maintenance, on-the-job maintenance of the 20 circuitry. 21 COMMISSIONER ASSELSTINE: Are those results being , 22 fed back in through EPRI or otherwise into the utility EQ 23 programs? 24 MR. McPHERSON: I believe they are, sir, yes. t 25 (Slide.]
, ,e .. - ------- ~ - . .,.,-.,--,,v n--.,e- . -.- .---.----,wmr.,,,,-,n., .-m. - , , .-w,. -.-.- -
57 1 Now I'm going to change the subject slightly. To 2 meet the program objectives that I mentioned right in the 3 beginning, I am going to just list the basic information 4 required, and from that, show you or give you a list of the 5 kinds of things we're doing in the future program. 6 We need to know the system configuration and the 7 operator actions that were taken at the time, the plant 8 initial and boundary conditions, the peak temperatures, 9 material interactions and extent of material oxidation. We 10 need to know the relocation, the structure, and the 11 composition of the core materials. 12 [ Slide.] . 13 The effect of control and burnable poison rods, 14 damage to control support assembly, the instrument structures 15 and to the reactor vessel lower head, and we need to know the 16 retained fission products and chemical form. 17 How are we going to find out that information? 18 (Slide.] 19 We go on now to the mechanisms that we have to 20 obtain that data. We have visual and we have acoustic 21 inspections. I will show you some photographs relevant to 22 those in a second. 23 We will be acquiring core bores, drilling down and 24 taking drill cores of the core. We will be defueling, of 25 courso. We are defueling. We have doftvaled about 8 percent
, , nn--- ,_ . _ , - - - , . - - - - - , - , , , - , - - , _ _ _ - ,.m,,--,-,-----~,-,-n,-,_, , - - - - - - , , . , , - - . , ,-
58 1 of the total core at this time; GPU has, I should say. 2 COMMISSIONER ASSELSTINE: Is that mostly the loose 3 sturf on the top? 4 MR. McPHERSON: Yes, sir. 5 (Slide.] 6 The other mechanisms we have are the *,nysical, , i 7 chemical, and radiochemical examinations of the core samples, 8 and perhaps I shouldn't take your time to enumerate them, but f 9 you can see them laid out there, various core components right 10 through, and finally the basement sludge and concrete drill 11 core bores taken from down below in the sump. 12 CHAIRMAN PALLADINO: With regard to core defueling, 13 there are parts of it, if I remember, you said you really 14 don't know the conditions, and you're going to have to have a i 15 chopping tool possibly? 16 - MR. McPHERSON: Yes. I'll be showing you the core 17 bore, the drill machine we have coming up now, and there are 18 many tools that GPU has developed, which I think they , 9 19 mentioned at their last meeting with you.- 20 And, of course, finally we will be evaluating and 21 qualifying the online instrumentation, and we are continuing 22 to do that. 23 [ Slide.) 24 The next slide is just to give you an indication of 25 a summary of the prioritized sample acquisition and
59 1 examination tasks we have. I have no intention .4 c" chrough
'2 them all for you, but you can see, we're going to be looking ,
3 at everything that deals with those different topics I've just 4 mentioned. 5 CHAIRMAN PALLADINO: Will you be able to get 6 information from all the samples that ycu have planned? 7 MR. McPHERSON: At this point, it still looks as if i 8 we can. 9 CHAIRMAN PALLADINO: With the funds available. l 10 MR. McPHERSON: Well, the funds are available, and 4 11 it's just a question of being able to locate those samples. 12 At times, they are difficult. GPU is not having an easy time 13 getting at some of the particular fuel bundles and control rod 14 materials that we would like, but we're working together with 15 them to try to do that. If we miss something, we pick out 16 something else to go for, and so far it's working out. 17 COMMISSIONER BERNTHAL: Is there a constant and 18 thorough, complete communication and interaction between you 19 and GPU on methodology, procedures, exactly how best to get at 20 the data? This is a little bit like a postmortem here, and 1 21 you don't want to -- you want to go at it in a way that I i , 22 trust the scientific community now reaches consensus on. I l i , 23 hope that's the way it's working. 24 MR. McPHERSON: Yes. We are using the assistance of 25 the scientific community to assist us in selecting this
- - - , , - .- ,, - - - , - . . . - . - , - . , ~ . - + , . . - . ~ . - . . , . - m.- . . , - - . , . , - ~ , ~ . , . .----.,,-.%-.mww,._m.wm,-r~,_.,m,-~.--.,-,..,,-._,--...,,.__
60 1 progran. But as far as the work goes, we are very closely
; 2 coordinating our interests with the work that is ongoing at 3 the Island. And this is why Mr. Vaughan brought to your 4 attention our continued presence on the Island. That is very j 5 -- it's essential to continue to work together so closely to 1 -
l 6 get the samples that we need. GPU is certainly very much in 7 support of our program, and therefore trying their best to get 8 the samples we want. 9 We have visits by Jim Broughton here every other 10 week, I think, to discuss how things are going, and or course ; 11 we have -- we're on the phone continually with him. 12 COMMISSIONER BERNTHAL: Well, that's good. I see , 13 some GPU people here, and I can't stress too much, I think, 14 that the public interest in this thing really transcends the 15 narrow interest or the narrower interest of the utility in 16 this case, and I am sure they're very sensitive to that and 17 hope that they work very closely with you and others. f 18 MR. McGoFF: We've already received substantial j 19 support from GPU in terms of laying out the scientific i
- 20 program.
21 COMMISSIONER BERNTHAL: Yes, I trust that's the 22 answer. ! 23 MR. VAUGHAN: And likewise, we're doing it in a 24 manner which doesn't delay the defueling in an untimely manner j 25 either, because it's obviously important to continue to get i t
l I
.' 61 1 the core defueled on schedule and get the fuel away. So it's 2 a give-and-take, but it's been a good give-and-take.
3 CHAIRMAN PALLADINO: Earlier you mentioned a 4 steering group. Could you tell us a little bit about the 5 steering group, how many people, the spectrum of talent, how 6 often they meet, what they give guidance on, for what it's 7 worth. 8 MR. McPHERSON: Yes, sir. We have had actually 9 three different names for groups that have been in place. I 10 CHAIRMAN PALLADINO: How many names? 11 MR. McPHERSON: Three different groups have been in 12 place as the program has evolved -- the Technical Evaluation 13 Group. I've forgotten the name of the second one. 14 MR. BROUGHTON: The Industry Review Group. 15 MR. McPHERSON: Industry Review Group. And now we 16 have an Accident Evaluation and Review Group. This has 17 evolved with the form -- as we have formulated our program. 18 The people involved, though, the representatives, 19 the people represent industry, always EPRI, IDCOR, B&W, GPU, 20 and universities, the NRC and DOE. 21 CHAIRMAN PALLADINO: I was trying to connect this to 22 the question that was raised about getting scientific input on 23 making sure that you are taking advantage, maximum advantage 24 of the opportunity that we have here. 25 Do you have independent scientists, or is that --
62 1 MR. McGOFF: The Chairman of the Review Group is i 2 Dr. Todreos. He's brought with him a group from the 3 scientific community and the laboratories to review the 4 program and to make sure that we're doing the right thing. 5 CHAIRMAN PALLADINO: Well, I don't want to dwell on I 6 it. j 7 MR. BROUGHTON: And I would like to add one other 4' 8 thing, Mr. Chairman. ' 9 We also bring together groups of specialists when we j 10 have significant results. Last March, we had the first i . 11 evidence of fuel melting in our examinations of the debris ) 12 from the upper plenum, and we brought together a group of
- I i
l 13 well-respected metallurgists with a great deal of experience 14 in UO-2 fuel, light water reactor safety research to review ; I l 15 those results and to see if they concurred with the i t 16 conclusions we had obtained at Idaho in our evaluations, and , 17 we will continue to do that as other technical results come 18 about that warrant such a review. I { 19 MR. McPHERSON: If we can move on, if there are no l 20 further questions, I have some photographs here to back up i
- 21 what I was saying earlier.
t f 22 (slide.] I { 23 A photograph of the core bore hardware, which has l- 24 been tested in Idaho. It was designed by the oil industry and r 25 is typical of the technology used in drilling for oil, and it ' i ' I \
,r--
- + -,-- - .,.-..r,.,-.-.,-e,- ,y,.e.w. , , , . , , - ,y-,-,-,.____m---..wm-e.-w-,w,_.., ,w. . - -,, .,.2.,3,----.w, ..-.---.,vy, ,aw w --% e w , ,g,= , , . _
i
.' I 63 1 uses drill bits which will go through concrete and steel and ,
2 any other substance whose nature we think we understand in the ' 3 core. 4 It is a very sturdy piece of equipment. It has been 5 well tested and is about to be set up over the core at TMI to 6 start drilling those samples we mentioned. 7 The way in which it functions is shown in the next 8 slide, and I won't dwell on it but just to say we can drill 9 right down through as far as we need to. 10 (Slide.) 11 COMMISSIONER ASSELSTINE: And no further. 12 MR. McPHERSON: No further. It is physically 13 limited. We have some strong constraints from GPU. They will 14 not go into the lower plenum and touch that lower plenum 15 material at this point. 16 MR. McGOFF: They ron't allow us to bring more drill 17 bit into the containment than would reach a certain depth. 18 COMMISSIONER BERNTHAL: I can understand that. 19 (SLIDE.] 20 MR. h:PHERSON: We will be doing an acoustic 21 topography measurement to help us understand the topography of 22 the crust. 23 (Slide.] 24 That takes us on to how we put this whole thing 25 together. I don't want to dwell on this one either. I havo
- .' 64 1 told you that we are continuing to look at the and state of l
2 the reactor system and the on-line data, and we are doing ; 3 independent severe accident -- using the results from i . 4 independent severe accident research, all feeding into an i 5 analysis group, an evaluation group which is putting this 6 whole picture together using codes, developing the necessary 7 models, and in the long run, we, of course, hope to have a 8 comprehensive TMI accident scenario. 9 As this is proceeding -- and now we are getting to a i lo qeustion that the Chairman raised earlier -- we are getting
, 11 to the point where we are able to formulate the TMI standard
{ 12 problem. 1 . 13 (Slide) 14 By that I mean we are able to define the initial and 15 end conditions, the uncertainty in the various data that we ! 16 have measured, and we are able thus to provide that 17 information to different code users to attempt to understand, t i l 18 to benchmark their codes against this accident, and thus l 19 compare the behavior of the codes, get more insight into the i 20 accident. And you can see there would be some feedback to 21 understanding the accident, as well as the most important 22 thing, arriving at an independent consensus by the various I 23 participants. 24 We are nearing the point where we will be able to 25 perform the standard problem, or benchmark problem is a better i i
. - - . , - - - - . _ . _ , , _ - . . . . - _ - . _ _ . . . . . . , _ . - _ _ _ . . - , _ . - _ , - - . _ _ , ~ - . . _ _ , _ _ _ . . , _ _ . , . _ . , _ . _ , _ _ . _ _ _ , , , _
. 65 1 way to put it since standard problems are normally 2 well-designed experiments that you apply to codes.
3 COMMISSIONER BERNTHAL: I was going to say I hope 4 this is a rather unique problem, not a standard one. 5 MR. McPHERSON: Yes. We are using the word 6 " standard" only because it is standardized and we have a 7 methodology for getting people together. 8 MR. VAUGHAN: It is a reference problem. 9 CHAIRMAN PALLADINO: What are you going to do, 10 develop codes and methodoligies that would predict what yau 11 found? 12 MR. McPHERSON: Yes, cir. 13 MR. VAUGHAN: And can be then used to predict other 14 scenarios based on having been correlated to the factual 15 evidence. 16 CHAIRMAN PALLADINO: Good. 17 MR. McPHERSON: Of course, we have many codes and 18 they are proliferating now around the world, and many 19 countries are interested in taking part in this. Mr. Vaughan 20 alluded to this earlier. We have invited the OECD, the CSNI 21 of the OECD -- do you know those initials all right? -- to 22 sponsor the meeting of all interested countries to get l 23 together to define the standard problem with us. We then wil3 24 be able to all work from the same data base and go home to our 25 different countries and do these calculations, come back and l l
+
66 1 discuss the results. i 2 I can't emphasize more the importance of having an 3 independent assessment of both the accident and their codes so 4 that they together can come up with a consensus of how good 5 their codes are and how much we understand this accident, what 6 phenomena need to be studied further. 7 The first meeting of that group will take place in 8 Idaho at the and of April this year, and we expect then to 9 have the standard problem available for them, the defined 10 problem, let us say, the initial boundary conditions of the 11 accident, available to them by September of this year. i 12 I am sure it will go on for one to two years because 13 we are only going to be getting more and more data over the 14 next two years from this program, as we will see at the end
- 15 when we got to the schedule. I would hope, then, that there 16 would be feedback from the data that we develop in our program 17 to the severe accident standard problem participants.
18 We have had initial indication of strong support for 19 this program and are anticipating probably eight countries 20 will be represented and be running this problem. 21 Incidentally, they will also be asking for different 22 samples from the core to analyze those in their hot shop, in 23 their hot cells in their own countries, and dividing and 24 sharing the data that they obtain, with us and each other. 25 (slide.)
3
- 67 f 1 My next Vu-graph shows the research methodology. I -
; 2 won't spend long on it, but I have an important point to I
i l 3 make. You are well aware of the approach we take of separate ! l !
- 4 effects models going through to reactor system models and !
i 5 applying that to technical issues and eventually an acceptable j f 6 reactor system model. Of course, the research that feeds that ! i 7 stepwise methodology starts with separate effects experiments, ! 8 reactor system simulations, and all feeds into the end result. ! ] ,1 ' j 9 TMI, you see, as indicated in the lower part of this : I 10 Vu-graph, that oval indicates how TMI fits both into the {
! t j 11 separate effects programs, the reactor systems and directly 1
12 into the technical issues.
~
l
; 13 Now, I thought it important to point out that this !
I 14 isn't the whole story. I don't believe that we will get that i ( 15 and arrow, that and balloon with all of the data that we have ! l j 16 provided so far in your severe fuel damage program, nor from ! j 17 TMI. There are bound to be some voids in our knowledge, and i 18 unfortunately, we have no facility, n: significant reactor { l 1
, 19 facility in this country remaining operable now. PBF and LOFT j 20 are shut down. You have ACRR, but that is a very small i
j 21 facility. 1. ! 22 I want to emphasize that we must keep our l { 23 connections up with our international friends. There are j i 24 still reactors in this world capable of doing experiments of + 25 the nature that will get us to that and point, and we must i
4 a 68 1 maintain our good relations with those other countries.
/
2 I think the standard problem is one way in which we 3 do it. Clearly, we win in many ways. One, we have facilities 4 to gain additional data from, but we have an independent
, 5 approach which can't be faulted by, let's say, the intervenors 6 if the question comes up as to parochial funding. If the l
7 world is together on the conclusions we come up with, I think ' 8 that lands strong weight to the results. 9 COMMISSIONER ASSELSTINE: But what you are saying is 10 now in terms of research facilities, we are totally dependent 11 upon facilities overseas. 12 MR. McPHERSON: Aside from Canada, which is not i . . 13 quite overseas, but yes. 14 COMMISSIONER ASSELSTINE: Outside the U.S. ! 15 COMMISSIONER BERNTHAL: I'm tempted to say.tell it 1 16 to OMB. 17 CHAIRMAN PALLADINO: It is an unfortunate situation, ! 18 but I guess we ara not here to solve that. 19 MR. McPHERSON: No. - l 20 CHAIRMAN PALLADINO: I would like to see if we can 4 i 21 adjourn by 4 o' clock.
- 22 MR. McPHERSON: We are at that point, yes.
23 (Slide.) ' t 24 The program schedule is laid out here, and I don't ' l 25 need to go through each item. It is only to show you that in '
- - - - - , _ - -. , - , ,------4-_, - . . . ----..- . - . _ , , , , . , , , . . . . ~ .v.m_ ~ ., _ _ _ - - , __ - . - . , - - - - - . ~ . - - , . - - - - , _ - , , . ."
- 69 1 the mid '87 to and of '88 calendar years, we will be really 2 reaping the benefits of this program.
3 CHAIRMAN PALLADINO: Will you be doing testing in 4 1987, sample testing? 5 MR. McPHERSON: Sample examination, yes, that's 1 6 correct. . 7 CHAIRMAN PALLADINO: And in 1988 also? ' 8 MR. McPHERSON: And in '88. j 9 CHAIRMAN PALLADINO: Then does your funding cease? j 10 Is there nothing after '887 11 MR. McGOFF: On the TMI program, yes, sir. We 12 probably will carry on some additional on the TMI-3 under the 13 base program, as Dr. Vaughan mentioned earlier. l t 14 CHAIRMAN PALLADINO: The base program. Whose -- 15 MR. VAUGHAN: Our base safety and licensing R&D 16 program. 17 CHAIRMAN PALLADINO: And you will carry that on 18 beyond '887 j 19 MR. VAUGHAN: If it looks like there is more to 20 learn, yes. I 21 CHAIRMAN PALLADINO: I thought even your base 4 22 program was going out of existence. 23 MR. VAUGHAN: We were not planning to take it cut of j 24 existence. 25 CHAIRMAN PALLADINO: Good. I'm glad to hear that. r
, 70 1 MR. VAUGHAN: It is not as broadly funded as yours 2 is, Mr. Chairman, but it is about an $11 million effort for 3 basic R&D licensing effort.
4 CHAIRMAN PALLADINO: When I read in the trade press, 5 I get the impression that everything you are doing is related 6 to military. 7 MR. VAUGHAN: I think that is an overstatement by 8 the trade press in what you are reading. I know NRC doesn't 9 have those problems, but we occasionally do. 10 (Laughter.) 11 (Slide.] 12 MR. McPHERSON: I probably should conclude at this 13 point by a simple statement. The TMI accident has enhanced i 14 our understanding of severe accidents and source term 15 phenomena. The accident will provide an important,. unique 16 benchmark of severe accident codes and methodologies, and the 17 accident provides a unique research opportunity: a severe core 18 damage accident in a full-scale plant. 19 CHAIRMAN PALLADINO: Thank you. Let me ask you one 20 question. I forget which slide brought it to mind. I guess 21 I'm pretty sure not everything in the containment was 22 environmentally qualified for the conditions it met. 23 Apparently there were some off-the-shelf items. 24 Did they survive well enough to do their functions? 25 Do you have any conclusions on that? You know, we are
, 71 1 spending a lot of money on equipment qualification to make 2 sure that it can function under the environment that we might 3 expect, and I was really interested whether you got any clue t 4 from the experience at TMI on those items, terminal blocks, 5 anything else that might be involved.
f 6 MR. McPHERSON: My comment is limited to my reading f l 4 7 of that one report I referred to and would indicate that by 24 2 l 8 hours, there were a lot of instruments not functioning
- l 9 adequately, and therefore, I would support any program which 10 ,
would qualify instruments to operate in this conditions. l l 11 CHAIRMAN PALLADINO: I want to examine "not ' 12 functioning adequately" just a moment. Had some of the 13 equipment performed the function it was designed to perform or l 14 were you still expecting it to function during the course of ; 3 ; 15 the accident so you can have more information? l t 16 MR. McPHERSON: I think it is best I defer this, if i
~
17 you would like to ask someone from GPU to respond to that. 18 CHAIRMAN PALLADINO: Maybe you ought to give me the i ! 19 reference for the report and I might spend a little time l { 20 looking at the report. I ] 21 COMMISSIONER ASSELSTINE: I think that is a good j r 22 idea. I think it would be useful to look at the report.My ( i .
)
i 23 CHAIRMAN PALLADINO: Maybe after the meeting. 4 ( a i 24 MR. McPHERSON: I will call your assistant with it. 25 CHAIRMAN PALLADINO: Good. I i i 1
i
- 4 j , 72
- 1 Well, I found that a very useful and interesting !
; 2 presentation. I don't know if there are other questions or !
- 3 comments commissioners want to raise at the present time.
s l 4 COMMISSIONER BERNTHAL: I have a quick question or 5 two. It is probably too early to tell, but would you be so l J l . 6 bold today as to characterize the quality, I guess, and [ 7 perhaps quantity of the source term information that might
! 8 derive from further analysis here? Would you say it is likely I ;
i 9 that this would be rather definitive or simply assist in our ! 10 understanding? How would you characterize it at this point? { i 5 11 MR. McPHERSON: My reading of what I have learned 12 from my one year on this project and talking to the experts is
. o 13 that it will qualify the data that ws are producing from our [
I i j 14 more definitive experiments. It will support but in some ' i j 15 cases surprise us. As Jim Broughton mentioned, in a big ' l 16 system things don't happen the way they do in a nice, ' I 17 well-coordinated and characterized experiment. . 1
; 18 The existence of a variety of metals, a variety of I I
j 19 atpospheres may certainly alter the source term or the fission 1 l 20 product behavior, and those are the things that we will learn
! 21 from the TMI accident. >
)i 22 COMMISSIONER BERNTHAL: It sounds like it is too i j 23 early to tell. j
! l 24 One other question. I think it is fair to say this l II l 25 was a core melt accident. There has been an inclination not i
I
, 73 1 to call it that, but it is quite clear now that it was. Is it 2 fair to say, then, that the step beyond where we are right 3 now, that is, if we have had a fairly definitive, complete 4 core melt accident within vessel, then I prasume that it was 5 this saving element of two feet of the core remaining 6 underwater and perhaps the bottom structures remaining 7 underwater as well that then formed the boundary between that 8 anc the next step of core on the ficor, as some of our staff 9 are wont to call it.
10 Is that a fair characterization of where we are in , 11 the assessment of the accident itself now? 12 MR. McPHERSON: I think that is a fair assessment, 13 though whether the core would be on the floor or in less 14 water, I don't think we can say. 15 COMMISSIONER BERNTHAL: Well, less or none. None 16 probably is the more important question. I 17 MR. VAUGHAN: I don't think we have the data to say 18 that even if there had not been any water there, whether we 19 would have breached the vessel. 20 COMMISSIONER BERNTHAL: No, you don't have the data l 21 and you never will, but one hopes -- t 22 MR. VAUGHAN: I hope we never get that data. 23 MR. McG0FF I would take that lesson that only a i 24 small amount of water is sufficient for the progression, and l 25 then use that lesson in future reactor design to make cure we ! u
i
, 74 l j 1 always have an amount of water -- ,
2 COMMISSIONER BERNTHAL: Well, I quess what I am
; 3 asking is, and let me put it this way, is there any reascn to !
t 4 believe -- you know, you guys are the nuclear engineers, I'm l 5 not -- that if that small water inventory had not been there, I ] 6 that you would not then have had a continued progression, or ! 7 is there reason to believe from what you have seen that the - i 8 usual scenario that one imagines may not have obtained here? i 4 ! 9 Is it too early to say, or you don't know, or -- i 10 11 MR. McPHERSON: Too early to say. 12 MR. VAUGHAN: I think it's too early to say. I t ] i j 13 think we haven't done that analysis nor really looked well ; j 14 enough at the conditions of the structure in the bottom. ! 15 Remember we are doing this with very remote, thin, TV i ! 16 cameras. It is too early to tell. t
- 17 COMMISSIONER BERNTHAL
- Is that thing accurate? I
, 4 J 18 have been looking at that for two hours now. Is that supposed
- 19 to be an accurate scale reproduction of how you see things at 20 this point?
I 21 MR. BROUGHTON: It is a scale model of the vessel 1 i, 22 and approximately where the debris currently resides within ! 23 the vessel. : 24 COMMISSIONER BERNTHAL: It is a lot of debris. That 25 is a lot more than I had actually pictured in my own mind. 5 i
,' 75 i 1 CHAIRMAN PALLADINO: Lot me ask a question no$ quite 2 related to the subject but still sonewhat related. Will DOE'c 3 reduced funding affect in any way the TMI-2 cleanup, at least 4 so far as your activities or support are concerned?
a 5 MR. VAUGHAN: With respect to the TMI-2 program, the ;
- ,6 DOE funding is not reduced below what it was projected to be 7 back in fiscal year 1986 when we augmented the funding for the I
( 8 fact that thinga had been dolayed, so we anticipata in working 9 with GPU that it will not affect the cleanup program. ; 10 To further amplify your question, some of the 11 reductions in the advanced reactor development pecgrams that ; 12 you have been reading about in the trade press and budget 13 documents primarily relate to having to use limited funda to r l 14 meet some of our commitments for nuclear energy sources or 15 military and defense programs such as SDI, but we arc ' 16 continuing to maintain fairly level funding for our 17 light-water reactor programs, which include these and the 18 other advanced light-water reactor programs that we are doing 19 in conjunction with EPRI, that ought to lead, hopefully, to 20 the certification of some of the advanced light-water designs 21 that are being done by U.S. vendors in conjunction with 22 Japanese vendors, or with some of the mid-sized advance 23 light-water reactors in which a number of utilities have shown 24 interest in terms of adding reactors to their utility cyster 25 in smaller blocks than the 1000-megawatt reactors. ____ . -- -- a
l
. 76
, 1 So those efforts are fairly level funded in our l i 2 hudget. l 3 CMAIRMAN PALLADINO: I am glad to hear that you are 4 maintaining the basic program in those areas. 5 Are there other questions that ccmmissioners want to 6 raise? 7 COMMISSIONER ASSELSTINE: Just a comment, I thought a this was a very interesting presentation, and Jim, I think the 9 points that you made earlier about the extent to which the 10 core was contained with virtually no addition of cooling water 11 for that long period of time is quice remarkable. It's a very i 12 interesting presentation. 13 COMMISSIONER ZZCH: I would like to say too I 14 thought it was an excalient presentation. Of course, you are 15 involved in something that is not only fascinating but has a 16 tremendous potential in many areas. I hope that when yCu wind 17 up and as you go along, you will try to focus a bit on some of 18 what you might call the significant findinge. 19 I agree witn comsissioner Asselstine. I think the fact rat the cc a vessel ittei- *'a ruc or t; itself al obview;y stayed intact and
- ahe W a very sipuricant 22 terparature anf ;.reasure and so forth is what I woul 1 crpaider 23 very significant and should be highlighted in sene way fran 24 your reuearch.
25 Alno any other surprisas. In other words, was there L _ _ . . _ _ __ __ _ -- _ M
, 77 1 anything that we learned that really was new and perhaps could 2 be considered something that would he in the form of something 3 that you wore rather surprised to find out? Any of the 4 metals, any of the natorials that reacted perhaps in that '
5 harsh environment differantly than you might have thought. 6 And certainly lessons learned should be something l 7 that you should be thinking about all the time, it seems to 8 me, and obviously you are, but certainly one of the lessons 9 clearly, I think, is to keep the core covered. 10 COMMISSIONER BERNTHAL: A little bit of water goes a 11 long way. : 12 COMMISSIONER ZECH: Yes. 13 COMMISSIONER ASSELSTINE: The more the better. 14 COMMISSIONER ZECH: The more the better. But it t 15 really is, and perhaps there is something other that is less 16 obvious than that, but lessons learned, I think, so that wo 17 can apply them to future operations to help our plants operate 18 in a safe and reliable manner also might be something. , 19 The only reason I emphasize this is because you are 20 head down into all the technical details of it, I appraciate l l 21 that and that is very important, but as you go along, you may 22 come across some of these things that are important to take a 23 little bit of note of at the time so that when we have ! 24 finished all this, we will at least be able to boil it down to 25 some valuable findings that we can use to make sure that this
?
/
- k. -__.______N
,' 78 l 1 accident will benefit the public.
2 So those are the things I hope you will be focusing 3 on because I think there is an awful lot to be learned here, 4 and obviously we are learning a lot, and the GPU folks are 5 learning a lot and I recognize they are actually doing the 6 work, but I know you are working closely with them and with 7 our staff, too, but I think we should try to focus on what we 8 can learn. Although those are all fascinating things to you,'I 9 think from an operational and a safety standpoint, we should 10 really try to make sure we pull out the lessons, and I would 11 commend your effort to that as well as your continuing effort 12 to get the most from your research. 13 MR. VAUGHAN: Certainly, Commissioner Zech, no 14 lesson is more important than the basic one of if you can do a 15 better job of keeping the whole core covered and not having < 16 any voids, then you never have the accident in the first 17 place. My review and, I hope, your staff's review of some of 18 these advanced light-water reactor designs that I mentioned 19 just a few minutes ago show to me that a-great deal more 20 attention has been paid to that and that we would have had 21 several orders of magnitude or margin of keeping the core 22 covered in the first place than we had in the TMI-2 situation 23 and may never have even had the event, which is the best 1 24 lesson of all. 25 COMMISSIONER ASSELSTINE: Jim, I think that is a
. 79 1 very good point there. You are absolutely right. There are 2 some features in some of those advanced designs that clearly 3 would provide substantial additional margins of protection to
- 4 avoid getting into the accident situation to start with. That 5 is a good lesson to be drawn from it.
6 CHAIRMAN PALLADINO: Thank you very much, 7 gentlemen. That was a very useful session and we appreciated 8 your coming. 9 MR. VAUGHAN: We appreciate your taking the time to 10 spend two hours out of your valuable day to go through it 11 because it is important to all of us. ! 12 CHAIRMAN PALLADINO: It is these kind of sessions l 13 that help give value to our day. l 14 Thank you. 15 (Whereupon, at 4:07 p.m., the meeting was 16 concluded.] 17 l 18 19 20 I i ! 21 22 23 . 24 25
1 CERTIFICATE OF OFFICIAL REPORTER 2 3 4 5 This is to certify that the attached proceedings 6 before the United States Nuclear Regulatory Commission in the
.7 matter of. COMMISSION MEETING 9
9 Name of proceeding. Briefing by DOE on R&D Results from TMI-2 Cleanup (Public Meeting) 10 11 Docket No. 12 place: Washington, D. C. Is Date: Tuesday, March 11, 1986 14 15 were held as herein appears and that this is the original 16 transcript thereof for the file of the United States Nuclear 17 Regulatory Commission. 19 (Signature) g , , , (Typed Name of Reporter) Marilynn M. Nations 20 21 l 22 23 Ann Mlley & Associates, Ltd. 24 25
. . )
_ - _ _ - . _ , - . _ , - _ _ _ _ __ - - _ ~ ._ , _ _ . , _ . . - - - - _ _ - - - - _ _ _ _ . -
,' 3/11/86
' SCHECULING MOTES
. TITLE: BP!EFING BY DOE ON R&D RESULTS FROM TMI-2 CLEANUP SCHEDULED: 2:00 P.M., TUESDAY, MARCH 11, 1986 (OPEN)
DUPATION: APPP0x 1-1/2 HR$ AGENDA: J!M VAUGHAN ACTING AS$!STANT SECRETARY FOR NUCLEAR ENERGY U.S. DEPARTMENT OF ENEPGY INTRODUCTION CON MCPHERSON TMI-2 ACCIDENT EVALUATION PROGRAM MANAGER llGHT WATER REACTOR SAFETY AND TECHNCLOGY OFFICE V.S. DEPARTMENT OF ENEAGY
- PacGRAM OBJECTIVES
- ACCIDENT SCENARIO AND END CCNDITIONS
- ACCIDENT EVALUATION PROGRAM .
- SCHEDULE DAVE MCG0FF, DIRECTCR OF8!CE OF LWR SAFETY AND TECHNOLOGY U.S. DEPARTMENT OF ENERGY JIM BROUGHTCN, MANAGER TMI ACC! CENT EVALUAT!CN PACGRAfi EG&G IDAHO, INC.
l
e I i TMI-2 Accident 1 Evaluation Program i Presented by: Dr. G.D. McPherson U.S. Department of Energy March' 11,1986 P225-ALAS 4002-4A
5 2 0 0 0 8 A L A-5 2 . 2 s P _ n _ i o - i t - d n o c m d a - n r g e o e d n r p i n s a n l t e o o u i t v i r a i t a O c e n e l u a j b c v o s e t n t n e m e e l u a r d d d g i c i c e o r c c h c - P A A S
., . I!i i!i! llll4 '
l - ) I i Program Objectives
- Understand what happened during accident
- Apply understanding to resolution of severe accident source term technical issues i
a Transfer results of program to government, nuclear industry, and public t P228-ALASSOO2-28 1 i - _ _ ___ _ __ _ -- _ _ _ _ - . - _ _ _ _ _ _ _
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l Lower Head Debris I l A B C D E F G H K L M N O P R From RC-P-1A y From RC-P-19
- i. / <
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- 1 7 m spi e e e 3 3 3j e \ t.t 9 7: is e o e e l / /
. \sp,n ,, . . , . ;
_g' i 4 ii\ Q i m s %r ,: X = / a O/ 3 "\9h)yC; I A tKM / / 2 \ NWM 8 f 4 3'7 / 1 \ N _, j $ v- 'a / / N ]/M w@k From MC-P-2 A \b* W $.k
- b From nC-P-28 e r 9 in-core Instrument guide tubes Q Surveillance espeule accese holes (3-718')
(used for manipulator)
@ Vent valve accese holes (3-il8")
(used for esmeras and lights) O noi u..d in o.c.mb., iss. ...m
- Area inillally enamined ammme Bounds of present eneminallon
- Boundary of deep debrie bed (estimated depth at center -
almost 34*)
=== Extrapolated 4
"""" Sleep 'ellf f-like' structure ~4-12' high cve 3o41
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l 1 l 86-72-3, # 9 Lower plenum debris, y-axis: " wall" l of debris and vessel penetration
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i 1 i l 86-72-3, #7 Lower plenum debris, y-axis: nozzle
- on right of 86-72-3, #9
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- 86-72-3, #8 Lower plenum debris, y-axis: guide tube l l and nozzle on left of 88-72-3, #9 l l ,
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- 86-72-3, #6 Lower plenum debris, w-axis: penetration t
weld and debris near " wall" l l W egW
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I I 1 l i 1 i, ' l 86-72-3, #11 Lower plenum debris, w exis: bottom diffuser ' l plate with debris in 6" hole l l
Measured Reactor System Pressure History 2o. a pusep transient
- / :
i i+- HPIS on a3 - : - E P alock vah opened
,2_.
O i* o/
- c .. oe. ~
\ ~
E 2 As -
+-- Block vehre closed O
100 200 Time MtSS) me sr-ows-os l l f 1 l
Inco a Temperatures from Thermocouple Measurements Between 240-330 nanutes 1 2 3 4 5 6 7 e 9 to 11 12 13 14 15 l A A B ~~ 411 438 3 C Ste /. fe?
' C
.- . 43.0i-
- .- ,.. .- a D ; f ese ,. ,
/. / @ 378 D l I i ese. ,.- ,. r3eE.- B, sed j ,< 438 E r1 -
wieswa .-/ -
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m r Gl pass .# I ees .f . D a7 pass . nat.s'. ., .m..._ ,G n '4 ,g yh s
/ / _/e,,% .-
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.';- .est ,-taeq,-
l L Ii ese _e '..
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L g ' l M pieg /. IS.gg 440' e 385 M l436 1 . e s .- . ; N m j .'.jWe B.Sd . .
, N l
o dm . m m! o 1 r P , est j P l l l B i ... R l I 2 3 4 S S 7 8 9 10 11 12 13 14 IS l i l l 1
--m - - - , ,-
. l 1
)
l Core Condition Just Prior to B' Pump Transient (174 Minutes)
!iTri'!'i'!
- :: = = = = ,
Pf h 1 I l -
, sq 1- ' ;
a
!! f !
\ {
'I ~
f Highly oxidized l
/ rod like geometry '
l N' Relocated and partially
-' solldified prior molten core meterial I
i d : l Appronlmete coolant - liquid level '
% Solidified crust
=-
' aingi. , i intact fuel' rod stube 1
- q
* -n Jy,f
. )
)
MM i 4 l {,?A pu ,,,,,
-,.>,--,.+--+-,m--,p. ,,_,-e, -
,e,--,r r-, --.-..-m..-.--- m--++----*--- -
w-- --w--,
* - - - - ---%.-,- g-.,_e.2 sm. --- y ---.-___,,--4 %
Core Condition Just After
'B' Pump Transient (175-180 Minutes) j l
= =
!!I!'!'!'!4
= = =
, e = = ====%
mmmm , f7 1 ' T a 5- ' I -c - _l_ ,
,e n r
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> . 0. 0 . 0 . 0 0
\ 0 0 0
0;g ; gi g[ Qg i
- jj 9 5[jh , 3 pOxidized rod y $,
~ s i
s. s g l f \ l P )f j' k
- Debris bed of oxidized and
,,f l / previously molten 3
,::. I'l'g,j .- s.
.d[pr]i .
fuel rod materials
/
(,0K ?
'.h.v; q
, ; : . ~w '
a
'.1s ' Relocated and b))frf[jM n . I ; 'I,! ,
partially solidified
'D,, core material Intact fuel - -~
f Mhdh Wa'- "E
- O; d'1'VJ " Y rod subs '
)
~ <f'ng ~
r,.. C
%mi%,
uuu ,,,,, l l _______________________________-____-_________J
O Estimated End State Core - Conditions flf!9"i x
" /s! ! ! 5 555 9 ,
- I _l f -c f
3 r \ . r- N l d pam
' 0 0 c 0 r 0 0
- s od ubs
,) -
- 3 tan ( Core veld i
s/ 4) ic);)- i 1 region
^3 s i lh a t: ,
-Debris bed L 0 ,
qN, -Crust of prior
'f . molten material
?. . $ G "qe {hb
. z
- g/ ,
-Relocation of a I L ,
fn ~~_ : 45 ,i molten core
- f:
material extent of structural f,
- o ' damage unknown
[## Prior molten debris bed of coolable size
~
- cL -
_8 and geometry
%y, I UUU
~20 cm layer of non fuel material
? eene
i i l Summary of Estimated Radioisotope Distribution in the TMI-2 Reactor Estimated Percentage of inventory at Time of Accident Plant Location Kr _Cg_ I _Tg_ _Sr_ _ Bit _Ca_ l 1. Fuel and core debris 13* 27 33 nm 116 61 ~100 . } within the vessel i j 2. Vesselintomals and nm ~1 1 2 <1 <<1 <<1 . primary system piping l l 3. Primary system coolant <1 ~10 ~8 <<1 ~1 <<1 nm ' I 4. Reactor and auxiliary nm 46 41 4 ~2 <1 nm building sumps and tanks 1
- 5. Reactor and auxiliary nm <1 <1 <1 <1 nm nm j building surfaces .
! 6. Reactor building 64 <<1 <<1 nm <<1 nm nm ! atmosphere TOTAL 67 83 82 -- 116 61 ~100 l i nm = not measured (a) ceiculated for apparently intact fuel rods only pass sr.ois2 04 i
Radionuclides Released to Environment as a Result of TMI-2 Accident (*) - 4 Quantity in Core at Estimated Estimated Radio- Tune of Shutdown Quantity Released Fraction of nuclide Half-life (curies) (curies) Total Release i
**Kr 2.8 hours 6.92 x 10 7 3.75 x 10' O.15
'"Xe 5.2 days 1.42 x 10 8 1.58 x 10' O.63
*"Xe 2.2 days 2.11 x 10 7 2.25 x 10' O.09
Xe 9.1 hours 3.31 x 10 7 3.0 x 10' O.12
{ **Xe 15.3 min 2.00 x 10' 2.5 x 10' O.01
*I 8.0 days 6.55 x 10' 15 (b) l -
W Roeovin report V.II, part 2, pees 334
" On en estimated fractional basis of total nuclides reisesed. *I was very emell (about 16 curies se opposed to'about 2.5 million curies of noble gases)
PESS-ALAsette-11
- : ! ,l
; l< ;i
~ u- _ s s . lt t o s s ua s a a-i r s re t ed s a oig n r re a f h o a r m n t klro ep l mu uc e n e ad mo r e vge nc c d h h er l eo p S i c cn e t sa s , c l ra r t a em l eo e e _ n e f r o b gn d at cd s e wht ouw c a d na - l s o i i i gs l t l ala o so f c r a ne mo t ntnl c n e l ed o sp a i e eu l _ A c s l h a c t r at rd f oim c _ m t n cs a sy i hx t e cn acun . o r t e ela ee tb a ere t olp f i s dn i cn l of r s va s s n ot i da nc mie r n od ce r pn e i s abw eo o do p ld st t s f odlh i s nl ae i wcc i l ue st nl et u v i _ l eed oa et rn i obw a c i t l l b r are 2e ao2 n an ne - d coI o o i vee i ev I c e cM C Ab Ss ce Mc Ta l RiT n
i i Results of Instrumentation ! and Electrical Program i l-
- Most failures within 24 hours due to moisture intrusion i
i a No functional damage due to hydrogen burn l
- Use of radiation-sensitive transistors in some instruments
! caused functional failure l
- Off-shelf components less reliable; recommendations being developed i
l
- In-core th.ermocouples always give usefulinformation,
! in spite of virtual junction formation above 2200 K l
- Develop circuit diagnostic system.for normal maintenance i
i P225-ALA46002-318 l i
i l l Basic Information l Required from TMI-2 Research I
- System configuration and operator actions
!
- Plant initial and boundary conditions
- Peak temperatures, materials interactions,
. and extent of material oxidation
- Relocation, structure, and composition of I core materials ,
P228-ALA40002-13 I
! Basic Information Required ! from TMI-2 Research (continued) , I , 4 i !
- Effect of control and burnable poison rods
- Damage to core support assembly, instrument structures to the RV lower head l
- Retained fission products and chemical form i
a P226-ALAS 4002-14 i
l l l i i 1 i ! Mechanisms for Obtaining Data I i
- Visual and acoustic inspections i
- Acquisition of core bores i
l
- Core defueling operations i
i i P225-ALAS 4002-15 1 I
i ( i Mechanisms for Obtaining Data (continued)
- Physical, chemical, and radiochemical examinations i of core samples l - Fuel rod segments, core debris, and core bores i
- Fuel bundle, structural components-end boxes, l spiders, and springs ,
l
- CSA, instrument structures, and lower head l
- RCS surface samples and sludge
- Basement sludge and concrete drill-core bores l
- Evaluation and qualification of on-line instrumentation m . ..i.
9 Summary of Prioritized Sample Acquisition and Examination Tasks
- 1. Centrol core bore to lower core support plate and visuol enomination
- 2. Centrol core bore to lower hood and visuoi examination
- 3. Large volume somple from upper debris
- 4. Topogrophy of the crust below debris bed
- 5. Mid-rodius core bores to lower plenum (3 bores)
- 6. Locollorge volume somples of oobris from core support assembly region
- 7. Locollorge volume samples of debris resting in bottom of reoctor vessel
- 8. Two intoct, port length f.;al ossemblies from control rod and poison rod locations !
- 9. Outer rodius core bore to lower core support picte J
- 10. Bosement sludge somptes
- 11. Concrete samples from containment bosement walls
- 12. Primary cooling system surfoce and sediment somples from i A ond B loop steam generators, pressurizer, hot leg RTD I thermowells, and steam generator monway and hondhole covers
- 13. Somples of interoction zone between core motoriols and lower core support assembly
- 14. Somptes of interaction zone between instrument guide tube structures and core motoriol
- 15. Samples of interaction zone between reoctor vessellower head surfoce and lower core debris materials
- 16. Samples of interaction zone between core former wall and core
- 17. Fission product retention surfaces in upper plenum
- 18. Upper plenum leadscrews j
- 19. Upper end boxes, control rod spiders, and spring from top of core
- 20. Fuel rod segments from debris bed P225-At.A86002-17A
1 1 i i : t ' 11
~
.: 1
-+--.--m r
- \
.J**.
! Core Bore Hardware i i
r Q. ' u%
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. t_ ym- ,..m_ q !
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l l l l
Core Boring Machine Drilling machine .
,,h ' y(g i I Transfer cask roller , M w
!g! , Operator platform platform ii
.:1me- 3_ '_ N 339.f t. elevation interface Defueling platform work platform 7
ma M;.__ y Fuel 331 f t,6 in. elevation - " ' -- '
~
canister h ,- % carousel p mast 327 f t,6.in. elevation -
.. a %- '
Underwater . r: .- Shielded l
# transfer cask drill pipe / -e :-
~* ...
support structure'[ - m [. -
- ;j,,,, , ,.' ; ' .
. . - . . c-
- yd F]uel ;/
-, ; .:[:
? ...* i.l; . -
/- - *. .1. c'..
4:3.t:. 4 ,4 " canister \ .?.;c ..
- ,: ./ .- . r. . .. .
wi.':
$:S.
i:'.$ ..
' Drill %l fy I "1 (
'. .,'.M.:
.' casing y ~
Void - ' ~'~. -N
< L -
!:*3
- r. ....-
. /e l L 2.... ..
4.i :' .
- .u ,. . .- .:..+;
..: i ,
..i'.
- /. mm nummmmmmmmmmmmm 1 :.*.e - ::
g,. (1 -
- 8.i '.:, % ::,9u4W t .?? S.
,i r d : . a .
., J e :.. .. ..i.
..... ::. . . . . . ...:. : . ,c. .. . .w. . .z n. a:;... :.: .
.v. '.s.;i,..;
. . . .c.;.;:.. .n.- -
4072s
e n o y it a v m r o h r om e le gt n a f p t ar r ef o t f i l le uk r p 7 a r pat 9 3 O, l p 3 f Dw eo
- i 2
7 0 a g !A.! f r l o-
)
na
, ]
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.,A
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u o c A j14 i ;; i, !, l , l i iI i ;;f
l i i ! Development of Accident Scenario
- upper fuel detwis
- core defueling '
- lower pienum debris
,. - upper pienum damage - initial core degradetion ceiculations
- upper plenum temperatu' - qualify pressuriser and reactor system date
- core void measurements End-sta.te - evaluate reactor system response during initial
~
i - video data reactor systeen ECC delivery l ! (reactor vessell I chorectorization - estimate core /steiniese steel chemicalinteractions ! - wire probe - estimate reacter veneel well (lower plenum) date , i - estimate instrument tube peneers on damage ! - estimate doyeded core configuration and resulting heatup V ::)
' N
On-line w 'neering onelysis & Macht I 7 TMI date r 7 to torpret TMI date scenario ' i 5 k:: 6 ' 4
- source range detector dose evaluation
- SPND interpretetion
- reactor system date quellfication i
Independ -- PSF and NW .. sev.ere W damage ewes ,
,,,,e,nt 1
;;;- ,,, , torr tieeion
. atn eu ei m eli e uct .e.svior i - .
e portments ( ,, ,,,,,,, P228-ALASeOO2-1A i i i
\ . t t TMI Standard Problem i i i .
- Provide a full-scale severe accident benchmark i for best-estimate severe accident analysis codes
! and methodologies
- Compare alternate severe accident analysis l
techniques and methods l P226-ALAS 4002-20 t
i J l - j I l i i i Research Methodology i I r , } l Separate Reactor Technics & Acceptelde reactor effects systems issues 7 systems models i models models . i I ' ( , r ( w ' i separate , , evet**a i ettects smoutl** experienents; **W'* ; } { v
}
i ( .
) Interactive coupling oe m.* a***
. v. .7 %
Mechanisms ang pnomene 4 .,*:0 , ,.,ee,e ,eecto, n syst*** **'*
.t 1 ,
. 9:-
i i ! P22s-ALAS 40 2-2 i i
t l ! TMI-2 Accident Evaluation Program i i CY-86 CY-87 CY-88 CY-89 1 i i . I i i . I i i i l . . i I
- Task Descriotion Scenorio to Scenario to Finot 225 minutes core retocotion report Accident scenctio e v v v a
i s/ss 9/87 9/88 1 Tronsmit Phase 1 Finoi Phase-1 comporison comparison ! Stendard oroblem a PY" 9' N l s/as e/s7 s/es
- Standard problem dato bose i
Dato base a v , Complete data base development
- to/es to/sv l
i I Instrument a , Summary report i evoluotion and s/s7 qualification { ) P225-ALA86002-30
t TMI-2 Accident Evaluation Program (cont'd) CY-86 CY-87 CY-88 CY-89 J - 1 i i i i i i i i i i i l i i i l a j
- Task Descriotion acqu;re foot Retrieve ;netrument Sompte ocquisition ***Nore a bare aformY."oEso$pw a cNsYNw a,,Eer"neoo eTpiN l io/s7 to/se ,
- Somote Excert 1/ss 2/as y,e,s,,;n, l v inram mama 8== v rhos report Lower vessel debris i
Eam**/Ss Prepare core /87 7 Complete l Receive core a v bores for enom a enoms v Finai report Core bores bores at INEL 4/ss 9 11/a7 a/es Commence rod/as Distinct core components a = === a t = = = =a a_ v Finot report 2/as ' / 2/s? Begin 11/ 8 7 10 / 8 8 Complete upper core Core former wo'I red segmeni enom ****m' vFinos report commence looer core rod segment esom 3/37 g/37 Core support assembly O'** **C '
- 9 Finot report enoms 9/88 Final 1/88 report RV instrument penetrations Commence a v
' ' ' *
- 1/89 9/89
- RV lower hecd Commence a "#ir*P
Commer ce surfoce serfoce deposit Finot
- nom ifgg gfgg l
Ex-RCS FP inventory d***) '""* * * *
- a* * * '"v* ' '
Y E*Y and chemicol form 4/88 2/87 10/57 } e WW j Ex-RCS FP inventory a Commence madmant amam v sosement studies fino; report
! and chemical form to/es 2/e7 j P225-ALA86002-29 l
j I __ __ _ - - - - - - . _ _ - - _-
i ^
\
! Conclusions l 1 j
- TMI-2 accident has enhanced our understanding
-{ of severe accidents and source term phenomena I j TMI-2 accident will provide an important and unique benchmark of severe accident codes
- i. and methodologies
- TMI-2 accident provide.s an unique research opportunity: a severe core damage accident in a full-scale plant j .
' P225-ALAS 4002-24 __ __ - - - - - - - - - - - - - - - -- = . _c- ._
\
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~
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