Official Transcript of Proceedings

NUCLEAR REGULATORY COMMISSION

Title: Advisory Committee on Reactor Safeguards

Docket Number: (n/a)

Location: Rockville, Maryland

Date: Wednesday, July 10, 2013

Work Order No.: NRC-065 Pages 1-187

NEAL R. GROSS AND CO., INC.

Court Reporters and Transcribers

1323 Rhode Island Avenue, N.W.

Washington, D.C. 20005

(202) 234-4433
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1 UNITED STATES OF AMERICA

2 NUCLEAR REGULATORY COMMISSION

3 + + + + +

4 606TH MEETING

5 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS

6 (ACRS)

7 + + + + +

8 WEDNESDAY

9 JULY 10, 2013

10 + + + + +

11 ROCKVILLE, MARYLAND

12 + + + + +

13 The Advisory Committee met at the Nuclear

14 Regulatory Commission, Two White Flint North, Room

15 T2B1, 11545 Rockville Pike, at 8:30 a.m., J. Sam

16 Armijo, Chairman, presiding.

17 COMMITTEE MEMBERS:

18 J. SAM ARMIJO, Chairman

19 JOHN W. STETKAR, Vice Chairman

20 HAROLD B. RAY, Member-at-Large

21 SANJOY BANERJEE, Member

22 DENNIS C. BLEY, Member

23 CHARLES H. BROWN, JR. Member

24 MICHAEL L. CORRADINI, Member

25 DANA A. POWERS, Member
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1 JOY REMPE, Member

2 MICHAEL T. RYAN, Member

3 STEPHEN P. SCHULTZ, Member

4 WILLIAM J. SHACK, Member

5 GORDON R. SKILLMAN, Member

6

7 ACRS CONSULTANTS PRESENT:

8 RONALD BALLINGER, ACRS Member Elect

9 PETER RICCARDELLA, ACRS Member Elect

10

11 NRC STAFF PRESENT:

12 HOSSEIN NOURBAKHSH, Designated Federal 

13 Official

14 JONATHAN BARR, RES/DSA/AAB

15 ANDREW CARRERA, FSME/DILR

16 DAVE ESH, FSME/DWMEP

17 ED FULLER, RES/DSA

18 MELANIE GALLOWAY, NRR/DLR

19 TINA GHOSH, RES/DSA/AAB

20 KATHY HALVEY GIBSON, RES/DSA

21 CHRISTOPHER GROSSMAN, FSME/DWMEP

22 DEBORAH JACKSON, FSME/DILR

23 CHRIS McKENNEY, FSME/DWMEP

24 PAT SANTIAGO, RES/DSA

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1 ALSO PRESENT:

2 JOE JONES, Sandia National Laboratory*

3 LINDA SUTTORA, U.S. DOE

4

5 *Participating via telephone

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1 T A B L E O F C O N T E N T S

2 Opening Remarks by ACRS Chairman 6 

3 4.1 Opening Statement

4 4.2 Items of Current Interest

5 State of the Art Reactor Consequence 8 

6 Analyses (SOARCA) Uncertainty Analyses

7 5.1 Remarks by the Subcommittee Chairman 

8 5.2 Briefing by and discussions with 

9 representatives of the NRC staff regarding 

10 the draft NUREG/CR-7155 Report, "State-of11 the-Art Reactor Consequence Analyses 

12 Project, Uncertainty Analysis of the 

13 Unmitigated Long-Term Station Blackout 

14 of the Peach Bottom Atomic Power Station."

15 Proposed Revision to 10 CFR Part 61 109

16 6.1 Remarks by the Subcommittee Chairman 

17 6.2 Briefing by and discussions with 

18 representatives of the NRC staff 

19 regarding a proposed rulemaking to modify 

20 portions of 10 CFR Part 61, "Licensing 

21 Requirements for Land Disposal of 

22 Radioactive Waste."

23

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1 P R O C E E D I N G S

2 8:29 a.m.

3 CHAIR ARMIJO: Good morning. The meeting

4 will now come to order. This is the second day of the

5 606th Meeting of the Advisory Committee on Reactor

6 Safeguards. During today's meeting the Committee will

7 the following: 

8 (1) State-of-the-art reactor consequence

9 analyses/uncertainty analyses;

10 (2) Proposed revision to 10 CFR Part

11 61; and

12 (3) Preparation of ACRS reports.

13 The meeting is being conducted in

14 accordance with the provisions of the Federal Advisory

15 Committee Act. Mr. Hank Hossein Nourbakhsh is the

16 Designated Federal Official for the initial portion of

17 the meeting.

18 We have received no written comments or

19 requests to make oral statements from members of the

20 public regarding today's session.

21 There will be a phone bridge line. And I

22 believe Sandia has some people on that line. To

23 preclude interruption of the meeting, the phone will

24 be placed in a listen in mode during the presentations

25 and Committee discussion.
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1 A transcript of portions of the meeting is

2 being kept. And it is requested that the speakers use

3 one of the microphones, identify themselves and speak

4 with sufficient clarity and volume so that they can be

5 readily heard.

6 Before starting the meeting, I'd like to

7 introduce a new member, Member Elect Dr. Pete

8 Riccardella who is joining us for the first time

9 today. Dr. Riccardella offers 45 years of experience

10 in the nuclear industry. In particular, he is an

11 authority on the application of fracture mechanics to

12 nuclear pressure vessels and piping problems.

13 Dr. Riccardella has had significant

14 involvement with the American Society of Mechanical

15 Engineers during his career. In 2001, he became an

16 honorary member of the ASME Section 11 Subcommittee on

17 Nuclear Power Plant In-service Inspection. And in

18 2005 was named an ASME fellow.

19 Dr. Riccardella was a founding member of

20 Structural Integrity Associates which has been an

21 industry leader in failure prevention and failure

22 analysis for the nuclear industry. Welcome aboard,

23 Pete.

24 (Applause.)

25 With that, I'd like to now turn the
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1 meeting over to Dr. Bill Shack who will introduce the

2 presentation.

3 MEMBER SHACK: Okay. We're going to

4 discuss the SOARCA Peach Bottom uncertainty analysis

5 today. Again, we had a preliminary review of this

6 report back in April of 2012.

7 I think it's important because in many

8 ways it's the most ambitious attempt to characterize

9 uncertainty and a fairly complex problem we've had

10 since NUREG-1150. And so it's interesting to look at

11 the accumulation of knowledge and techniques that's

12 been developed since that time.

13 And we sort of think of it as representing

14 perhaps the state-of-the-art in uncertainty analysis.

15 This is why it merits a considerable amount of

16 attention from the Committee. And I'll turn it over

17 to the staff. 

18 MEMBER POWERS: Dr. Shack, before we turn

19 that over to the staff, I will acknowledge an

20 organizational conflict of interest with this work.

21 I did not participate in any aspect of the work, but

22 it is sufficiently closely involved with my

23 organization. I will not be participating in any way

24 in this discussion.

25 MS. GIBSON: Yes, I just wanted to
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1 acknowledge our partners at Sandia that are on the

2 phone that worked closely with us on this project. 

3 And as you noted, you often ask us

4 questions during these presentations about

5 uncertainty. And our answer is usually about the

6 sensitivity analysis that we've done. This time we

7 can actually answer your questions on uncertainty.

8 And we're very proud of that.

9 And I wanted to just take a minute to

10 thank you for the previous times that we've briefed

11 you on this uncertainty analysis approach that is

12 somewhat unique and novel, the chosen parameters and

13 the insights from the preliminary analysis. We also

14 got input on those things from our SOARCA External

15 Peer Committee. 

16 So we've had quite a few brilliant minds

17 on this project. And we're excited for you to hear

18 about the completed project and the good work that

19 Tina and her team at Sandia, others in the NRC and a

20 few other contractors on this project.

21 But, first, I'll introduce Jonathan Barr

22 of my staff. He's the project manager for SOARCA.

23 MR. BARR: Thanks. I'm a reactor systems

24 engineer in the Office of Research in the Accident

25 Analysis Branch and probably the last project manager
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1 for the SOARCA project.

2 (Laughter.)

3 I'll just sort of introduce this and talk

4 about the agenda. And then Tina will discuss the

5 actual uncertainty analysis.

6 MEMBER SHACK: There's a Surry uncertainty

7 analysis coming. You're young enough.

8 MEMBER STETKAR: This is a career path.

9 MS. GIBSON: He's the 12th project manager

10 we've had for the SOARCA project.

11 MEMBER REMPE: He's coming in for the home

12 run though.

13 MR. BARR: It's a big project. So I'll

14 start with a little background on the best estimate

15 analysis and where that stands.

16 And then Tina will start with the

17 conclusions of the uncertainty analysis, the

18 distribution of results. She'll talk about the most

19 influential parameters, a comparison of weather

20 uncertainty to the epistemic uncertainty.

21 And then she'll get to some separate

22 sensitivity analyses that were done on various issues.

23 She'll touch on a few other areas of content in the

24 uncertainly analysis report.

25 And then I'll finish up with some next
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1 steps and path forward for bringing this report to

2 final publication.

3 The best estimate analysis for SOARCA is

4 documented in four primary reports which I have here,

5 the main report. We have the nice color brochure and

6 then we have the two thick reports for each of the two

7 pilot plants studied, Peach and Surry.

8 Those four went public in January of 2012.

9 In the following time, we received comments from the

10 public and held some meetings with the public. Also

11 a RIC meeting to get some feedback. We then revised

12 all four of the documents to address some comments,

13 add some clarification in certain sections.

14 The four reports were then sent to the

15 Commission in June of last year along with a

16 Commission paper in which we provided the conclusions

17 of the study and also recommendations for some follow18 on research. You heard mention the Surry uncertainty

19 analysis which is one of them. And then a similar

20 type of analysis to the Peach Bottom and Surry

21 analysis for an ice condenser plant.

22 In December of last year, the Commission

23 sent us an SRM approving those recommendations based

24 on available resources and relative priorities with

25 other high priority projects, notably a Level 3 PRA
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1 project.

2 We published the final version of the main

3 report in November of last year. The brochure went

4 final the following month. And then more recently we

5 have the technical reports going final. There's a

6 very long queue in the publishing office. It takes a

7 long time for them to review these and get these out.

8 MEMBER STETKAR: Jonathan, before you

9 leave this, something that I really need to

10 understand. You have a bullet that says those were

11 best estimate analysis reports. The results of the

12 uncertainty analysis in most cases showed that the

13 mean value of the results is substantially different

14 from the results in those reports.

15 So I need to understand how you as the

16 staff define the words "best estimate." We usually

17 define best estimate as either the mean, the expected

18 value of something, accounting for the uncertainty.

19 Some people say that it's the median because there's

20 an equal likelihood that a value could be higher or

21 lower than that.

22 But regardless of whether I use the mean

23 or the median, the numbers in those other reports

24 differ quite substantially from the numbers in the

25 uncertainty analysis. I'd like to understand how the
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1 staff defines the term best estimate.

2 DR. GHOSH: I think we had a discussion

3 about this last April. And we tried to explain what

4 we did for the best estimate. In fact, while we were

5 doing the uncertainty analysis, the team thought very

6 long and hard about whether we should update the best

7 estimate if there was anything that we had found that

8 would cause us to think that what we had done for the

9 deterministic analysis was not right.

10 And in the end we decided that

11 we would keep the SOARCA project estimates as they

12 were for the following reasons. That was a

13 deterministic analysis as you know. And what was done

14 was the best sort of collective knowledge in terms of

15 the severe accident modeling community, both from

16 MELCOR and MACCS.

17 For each parameter the kind of best value

18 was chosen in terms of what collectively we thought is

19 the appropriate value for any given single parameter.

20 And those were plugged in to a deterministic analysis

21 to get what was called the best estimate result.

22 As you know in the uncertainty analysis,

23 quite a few of the results turned out to be in terms

24 of the release magnitudes and also the health risk

25 turn out to be higher. And that's primarily because
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1 we ended up having two additional subscenarios within

2 the long-term station blackout.

3 So the SOARCA scenario was the one where

4 we have an early stochastic SRV failure which is one

5 group of scenarios in the uncertainty analysis. But

6 in the uncertainty analysis we had some that

7 progressed to a main steamline creep rupture where you

8 have a significantly higher release or one where the

9 SRV failed quite a bit later which allowed core damage

10 to begin before you had SRV failure. And there you

11 had higher releases, too.

12 The one we evaluated, the entire body of

13 knowledge that we had, the team still felt pretty

14 confident that the most likely scenario was still an

15 early failure of the SRV. And we talked about this in

16 April as well that one of the challenges we had in

17 trying to assign the distributions. We don't have any

18 data. We don't have any hard experimental data or

19 certainly not any real life data where we have SRV

20 testing at severe accidents and pressures and

21 temperatures.

22 So we took our best guess at coming up

23 with the distributions, the failure distributions, for

24 those parameters. But the truth is that it's highly

25 uncertain. We don't know what the real distributions
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1 of those parameters are.

2 MEMBER BANERJEE: Could I ask you a

3 question here?

4 DR. GHOSH: Yes.

5 MEMBER BANERJEE: We deal with this all

6 the time. If you don't know the distributions, you

7 can do non-parametric statistics, a sampling of these.

8 And you can get a measure of the uncertainty provided

9 you know the bounds. And this is commonly done all

10 the time.

11 DR. GHOSH: Right. We're not sure we even

12 know the bounds. I think that's --

13 MEMBER BANERJEE: You don't need to know

14 the distributions. That's all I'm saying.

15 MEMBER STETKAR: One of the points, we're

16 going to be short on time here. So I don't want to

17 belay this too much. The fact of the matter is even

18 if you look at some of the uncertainty distributions

19 after you've had your experts go back and really think

20 about the uncertainties. The mean values of even the

21 parametric uncertainties in many cases are different

22 from the point values that you use. 

23 Forget the overall results for the moment.

24 Even on a piece parts case, when you went back and

25 thought carefully about the uncertainties the experts
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1 or the available data or whatever process you used to

2 develop those uncertainty distributions resulted in

3 different mean values or different median values from

4 what was characterized as the expert's best estimate,

5 using these words, before they thought about the

6 uncertainty.

7 And the only point and we talked about

8 this in April is that the way studies ought to be done

9 is the experts and the data ought to be minded for the

10 available uncertainties first and derive a best

11 estimate from that. And then in some sense you might

12 be able to characterize those point estimate

13 deterministic analyses as may be close to what you

14 would expect the best estimate to be.

15 And the only reason I raise this is going

16 forward in the uncertainly analysis report you've

17 established the term "SOARCA base case" or something

18 like that to kind of characterize the 7110 results if

19 you will which is fine.

20 But here now we're starting to see these

21 words "best estimate" again. And they start to tend

22 to take a life of their own. People start to defend

23 them as if they're what we really should characterize

24 as a best estimate result. 

25 So I caution you going forward. I mean
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1 you're not going to rewrite those NUREGs but going

2 forward to be really sensitive to that.

3 MEMBER CORRADINI: So can I just ask it

4 differently? In the short one, the only one that

5 anybody will read, the pretty one, does it say best

6 estimate or does it say base case? I think that's

7 what John is getting to. From an illustrative

8 standpoint, I assume it says base case, a

9 deterministic base case, engineering base case rather

10 than best estimate.

11 MR. BARR: I think that this one does not

12 use either of those terms because this only minimally

13 discusses the uncertainty analysis.

14 MEMBER CORRADINI: But what do you

15 characterize the deterministic analysis as? I do

16 think to the extent that engineers have this tendency

17 to run out there and do a calculation.

18 MEMBER STETKAR: I just did a word search.

19 Best estimate doesn't appear in that document.

20 MEMBER BLEY: I want to follow up a little

21 bit because what I thought I heard you say is after

22 you went to all the effort to do the full uncertainty

23 analysis and put in the best distributions including

24 the limits that you could come up with you have more

25 confidence in your base case analysis than you do in
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1 the uncertainty analysis. And that I don't understand

2 at all.

3 DR. GHOSH: I think it's more that the

4 same team that did the SOARCA project also we had the

5 same subject matter experts for the uncertainty

6 analysis. And it's more that we revisited what had

7 been done in the SOARCA project to see if we had

8 uncovered anything that we would have changed, that we

9 should said, "No, we did it wrong. We can't call

10 this" -- I don't want to use the words best estimate

11 anymore but that we would have updated the SOARCA

12 project NUREGs.

13 In the end, the thought was that we

14 wouldn't. The original project as it was including

15 the values that were chosen for the parameters if we

16 had to do a deterministic study, it's still our best

17 guess. 

18 As I mentioned for some of the key

19 distributions in the uncertainty analysis there was so

20 little data to go on in terms of assigning the

21 distribution. Again, we kind of used the collective

22 wisdom of the team.

23 MEMBER BLEY: That's what you use for the

24 point estimates as well.

25 DR. GHOSH: Yes, and it's the same group
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1 of people.

2 MEMBER BLEY: It's the same limited data.

3 But the uncertainty analysis allowed you to at least

4 encompass the range that you thought would be

5 involved.

6 DR. GHOSH: Right. So some of those

7 distributions are fairly wide. Part of the thinking

8 was that we have a good guess. If we had to pick one

9 number we're confident that this is the good number to

10 pick. But since we don't really know we want to see

11 -- 

12 We think that it might be and I think you

13 saw some of the distributions. It might be an order

14 of magnitude higher. It may be five times higher.

15 You know double. Whatever it was for the particular

16 parameters. It might be, but we don't think that's

17 the most likely.

18 MEMBER STETKAR: Tina, you have to be

19 careful here because some of the things that I'm

20 hearing you say is that people didn't think very

21 carefully about those uncertainties.

22 DR. GHOSH: No, no, that not it at all.

23 MEMBER STETKAR: I mean if they really

24 believe the uncertainties, the ranges and the shapes

25 of the distributions, then their real belief is that
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1 the expected value is the expected value. They should

2 feel confident in that expected value because they've

3 carefully thought about how large it could be, how

4 small it could be and the shape of the probability in

5 between those bounds whether it's flat or pumped up in

6 the middle or skewed out or however you want to

7 characterize it.

8 MEMBER CORRADINI: Before she answers, can

9 I ask a question? I guess you guy are going to go on

10 about this which is great. But I want to ask from a

11 process standpoint if this was like 1150 where I

12 prepared in it and I assume this is what you mean by

13 the subject matter experts. 

14 I would assume there's a lot of healthy

15 discussion about what the range is and what the shape

16 is, at least the range. Forget about the shape. The

17 shape I would make it uniform just because I don't

18 know what it is.

19 DR. GHOSH: Yes.

20 MEMBER CORRADINI: But the argument about

21 the ranges. What I guess John is asking is if

22 somebody has a real belief that they're sure it's

23 early failure of the SRV and they fight for that, did

24 the ranges that eventually come out of this

25 uncertainty, just the collective population had said,
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1 that person A was absolutely sure it was early term?

2 And he could have a deterministic reason. And subject

3 matter expert B was very uncertain and because of

4 just the range of the subject matter. In other words,

5 you took a wide range.

6 That at least in 1150 is how we got to

7 wide ranges because person A was sure it was this way

8 and person B was sure it was this way. And to cover

9 the bases of all the subject matter experts, you've

10 got a wide range with a uniform distribution. So I'm

11 trying to think of the evolution of how you determined

12 it.

13 DR. GHOSH: I would characterize the

14 distributions we settled on as consensus

15 distributions. It's not that each expert had a

16 distribution and we averaged them or something. We

17 collectively decided on what is a distribution that we

18 could live with.

19 MEMBER BANERJEE: Could I ask you the

20 question again?

21 DR. GHOSH: Yes.

22 MEMBER BANERJEE: Why this focus on

23 parametric statistics as opposed to nonparametric?

24 Why do you put this emphasis on the shape of the

25 distribution?
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1 DR. GHOSH: I apologize if I'm unduly

2 putting emphasis on the shape. I mean everything,

3 both the range and the shape. I think we have more

4 confidence in terms of coming up with a good range.

5 The shape is even harder within the range.

6 But you know we know from past uncertainty

7 analyses that the range is more important in looking

8 at the --

9 MEMBER BANERJEE: So you know what I'm

10 referring to. The Wilkes theorem, right.

11 DR. GHOSH: Yes, yes.

12 MEMBER BANERJEE: So why is this? Do you

13 ignore this? Is it unimportant?

14 DR. GHOSH: No. It's just the only

15 thought I --

16 MEMBER BANERJEE: I'm just trying to

17 understand why this emphasis on shape.

18 DR. GHOSH: It's not just on the shape.

19 I think that the bottom line is that for some of the

20 -- And we say this in the report. I think we're very

21 explicit.

22 MEMBER SHACK: But the input parameters

23 eventually end up that they have to have a shape. 

24 MEMBER STETKAR: There may be a shape if

25 indeed there's a state of knowledge or some data to
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1 support a higher probability somewhere in that range.

2 So it just doesn't mean that we don't know anything

3 about everything.

4 MR. FULLER: Excuse me. Can I offer

5 something here that might straighten out this

6 discussion a little bit?

7 CHAIR ARMIJO: Tell us who you are.

8 MR. FULLER: This is Ed Fuller, Senior

9 Technical Advisor in the Office of Research. I think

10 looking back at the results of this study there are

11 certain biases in a couple of the distributions which

12 emphasize one end of the range or another. And those

13 biases as you'll probably hear particularly with

14 respect to safety relief valve behavior have to do

15 with what the situation becomes when the temperatures

16 get very hot in the safety valves and the stems and so

17 forth.

18 And so the biases towards failure at that

19 time. And you can put a uniform distribution in if you

20 want. And the stochastic approach is somewhat that

21 way. You know if you look at this issue you see there

22 is early stochastic failure is one of the

23 possibilities which SOARCA looked at.

24 And then you have also looked at in SOARCA

25 what happens when the valves get hot, when the main
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1 steam line gets hot. And then you get the possibility

2 that certain things could be induced after that.

3 So you have to draw the distinction

4 between the early part of the distribution which is

5 fairly linear. And then later on when you really get

6 the bias towards the high temperatures.

7 MEMBER BLEY: Before you leave, Ed, it

8 seems to me that what you're calling a bias is what

9 you folks put into the distribution to account for the

10 fact that you don't fully understand the performance

11 up at that end.

12 MR. FULLER: That's true because no data.

13 MEMBER BLEY: Which seems a reasonable

14 thing to do.

15 MR. FULLER: Yes.

16 MEMBER BLEY: And I would then tend to

17 acknowledge that that's part of the thing that might

18 drive a mean up. But it's reasonable. It's the best

19 engineering judgment you have.

20 If you gave that kind of thought to the

21 way you did the distributions, it seems to me the

22 results of the uncertainty analysis is what you want

23 it to be.

24 MEMBER STETKAR: That's the thing you

25 ought to believe in.
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1 MEMBER BLEY: Yes.

2 DR. GHOSH: So let me -- Sorry.

3 MR. FULLER: May I sit down now?

4 MEMBER BLEY: Yes.

5 DR. GHOSH: Let me, I guess I'll say one

6 other thing and then maybe we can talk more as we go

7 along. One of the things that we think is most

8 valuable from doing this uncertainty analysis even

9 though we are not completely sure of a lot of the

10 important parameters, exact distributions or ranges,

11 the main thing is we wanted to see when you put

12 everything together which set of parameters is really

13 driving the uncertainty in your consequences. And

14 that's kind of the most valuable thing that we get out

15 of it.

16 The exact probability distributions I

17 wouldn't put as much weight on because there's a lot

18 of uncertainty in what we put into it. But we learned

19 a lot in terms of what is potentially important, which

20 parameters interact together.

21 And like other past projects, when you

22 have very complex systems with synergistic effects and

23 so on, you can have hundreds of uncertain parameters.

24 But in the end it's really just a handful of things

25 that are really driving the uncertainty in your
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1 results. And that's kind of what we were after. And

2 I think we did get a lot of valuable insights on that.

3 The exact minute probabilities of the

4 various outcomes I would not put as much emphasis on

5 as understanding the entire range of system behavior

6 and what are the important uncertainties that are

7 driving that behavior.

8 MEMBER BLEY: I agree with you a lot. My

9 last comment is if you have trouble believing that

10 you've got the exact range exactly right why are you

11 confident that you have some point estimate right? I

12 mean you've got the same factor effecting and at least

13 you're acknowledging that uncertainty when do the

14 uncertainty analysis. You're not just picking one out

15 of the cloud.

16 Go ahead.

17 MEMBER REMPE: Just quickly I've heard the

18 informal discussion, but I didn't see it in the

19 report. Maybe I missed it because it is a long

20 report. But there is a lot of documentation somewhere

21 on the input parameters. Because expert opinions will

22 vary when you get a new set of experts.

23 And the thought processes, I think that

24 should be emphasized somewhere that maybe I don't miss

25 in the report if it's not in the report now. But that
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1 the process has been documented. So in the future if

2 people go back and look at a particular parameter,

3 they can trace what has been done a bit more. And

4 that's true.

5 DR. GHOSH: We tried to, after we met last

6 April, beef up the documentation namely in Chapter 4

7 on the parameter distributions themselves. And we put

8 in some additional discussion in Chapter 1 in terms of

9 our overall process. But we can revisit that again.

10 MEMBER REMPE: Especially with the higher

11 level surrogate parameters. I could not find a

12 discussion that explained what particular lower level

13 parameters went into this higher level ones and how

14 the process is done. But that is documented

15 somewhere.

16 DR. GHOSH: Okay. We will revisit that

17 and make sure that there is enough there. We tried to

18 do more, but it's one of those things when you're the

19 people doing the work. It may seem like you've said

20 everything there is to say.

21 MEMBER REMPE: I could have missed it,

22 too. But I think that's something that I would be

23 very interested in seeing information on.

24 DR. GHOSH: Yes. Thanks. We'll take

25 another look at that.
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1 MR. BARR: Finish up with the background

2 area, in addition to the primary SOARCA reports we

3 have few others that support them. We are almost

4 finished with the best practices report for each of

5 the two codes views, MELCOR and MACCS, that describe

6 best practices for using those codes in these type of

7 analyses and highlight some of the differences between

8 models and parameter values compared to test studies.

9 And then also a report that described

10 distributions for non site specific parameters for

11 offsite consequence was completed recently. And this

12 is also referenced heavily in the Peach Bottom

13 uncertainly analysis.

14 We briefed the ACRS last April, the

15 Subcommittee, and then May of last year in the full

16 Committee. And we're now here today. And then we'll

17 talk maybe at the end if the group decides that there

18 should be another meeting later on.

19 DR. GHOSH: Okay. So I'm going to start

20 with the overall conclusions. I think we might have

21 shared some of this back in April because we already

22 had some insights. But I'll just repeat them here.

23 One of the main objectives of the

24 uncertainty analysis was to see whether the SOARCA

25 results and conclusions were robust, knowing that
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1 there is a lot of uncertainty in the systems. And

2 after doing this study, we would say that the

3 uncertainty analysis corroborates the SOARCA study

4 conclusions, the following conclusions, that public

5 health consequences from severe nuclear accident

6 scenarios, the ones that were modeled, are smaller

7 than we had previously calculated. And in absolute

8 terms, they're very small.

9 We see that even with a lot of the

10 uncertainty we see in the source terms. The releases

11 are still delayed enough that there is enough time to

12 take the protective action measures such as evacuation

13 and the long-term base still dominates the health

14 risk. This is from people coming back to their homes

15 if they've had to be evacuated.

16 There is essentially zero early fatality

17 risk. We say "essentially zero" because we have very

18 powerful computers. And we can calculate extremely

19 small numbers.

20 So in a handful of the realizations we did

21 we did calculate a number. But it is so small that a

22 lot of people just kind of laugh when they see numbers

23 in those ranges. But the computers did calculate non24 zero number. But we say essentially zero early

25 fatality risk.
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1 This insight which we already knew last

2 year and we already shared with you, a major

3 determinant of the source term magnitude and the

4 health consequences is whether or not we see a main

5 steam line rupture. And that is, of course, if you

6 have a main steam line rupture it bypasses the wet

7 well scrubbing. So it's leads to higher consequences.

8 And in some subset of the realizations we did see a

9 main steam line rupture.

10 The health effect risks vary sublinearly

11 with source term and this is again because the long12 term phase dominates the health risk. And people are

13 not allowed to come back until the dose is below what

14 we call the habitability criterion. Some people call

15 it the return criterion which is EPA has guidelines

16 and each state sets its own. So we use the

17 Pennsylvania State guideline for that.

18 And we saw that our analysis confirmed the

19 known importance of some things that we already knew

20 going into the analysis and we certainly also got some

21 new phenomenalogical insights. And I'll talk about

22 that a little bit later.

23 And we saw that using multiple techniques

24 to post-process the Monte Carlo results was much

25 better at providing an explanation of which sets of
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1 variables together were driving the uncertainty in the

2 results.

3 You know we originally had only started

4 with the linear rank regression. But that doesn't

5 capture the interaction effects among the variables.

6 So about halfway through the project we added three

7 more advanced techniques and that proved to be very

8 valuable.

9 Before I go into the distribution of

10 results, I understand there was some question about

11 what we actually did, the mechanics of the analysis,

12 what we did to get the results. So if you don't mind

13 I just want to flip first to one of the backup slides

14 which is slide 42 in the package.

15 Slide 42 just has the overview of what we

16 did with respect to the two-step Monte Carlo process.

17 MEMBER CORRADINI: You anticipate a

18 question obviously.

19 DR. GHOSH: Yes, I did.

20 MEMBER BANERJEE: Do you use Monte Carlo

21 because you wanted the shape of the outcome

22 distribution? What was it?

23 DR. GHOSH: When I say Monte Carlo, maybe

24 it means different things to different people. I just

25 mean that we ran the MELCOR model 900 times and then
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1 we ran the MACCS model 900 times.

2 MEMBER BANERJEE: I mean there's a

3 procedure you know when you do Monte Carlo.

4 DR. GHOSH: Yes.

5 MEMBER BANERJEE: You are doing Monte

6 Carlo because you want the outcome distribution. I'm

7 not trying to -- I'm just trying to understand why

8 you're doing this.

9 DR. GHOSH: Because as I said the main

10 point of the project was to see the possibilities. So

11 basically we ran our models 900 times and we got 900

12 answers with respect to how the source term might come

13 out and what the health risk associated with it is.

14 MEMBER BANERJEE: You did a strictly

15 parametric study.

16 DR. GHOSH: Yes. That's one of the things

17 we weigh out in the front. You're absolutely right

18 and we should call this a parameter of uncertainty

19 study.

20 MEMBER BANERJEE: Yes.

21 DR. GHOSH: We looked at just a couple of

22 the model uncertainties and a separate sensitivity

23 study. But we did not include the conceptual model

24 uncertainty in the study. So this is just in the

25 parameters, both in the MELCOR model as well as the
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1 MACCS model.

2 MEMBER CORRADINI: So to put it

3 differently just to clarify Sanjoy's even though there

4 might be differences in models you focused on given

5 the models how do I noodle with the parameters within

6 the models.

7 DR. GHOSH: Right. And since I think you

8 all know MELCOR has a lot of lumped parameters and

9 it's kind of a lumped parameter code. So some of the

10 parameters that we varied represent different possible

11 mechanistic models. From that standpoint, we're kind

12 of getting at some of the model uncertainties.

13 But in terms of the actual implementation,

14 we didn't vary the structure of the models. We used

15 the existing MELCOR and MACCS models and we varied the

16 parameter values.

17 MEMBER SHACK: I think that comes back to

18 Dr. Rempe's earlier question about the surrogate. You

19 really are lumping things together. And it would be

20 helpful to be clearer as to what you think you're

21 covering with those parameters.

22 DR. GHOSH: Right.

23 MEMBER SHACK: Which is why they deserve

24 probably more discussion.

25 DR. GHOSH: Sure.
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1 MEMBER REMPE: And how they were combined

2 because it's unclear if you used the original model or

3 not or what was done.

4 DR. GHOSH: Okay. I appreciate that.

5 We'll take another look at Chapter 4 to make sure that

6 it's more clear with respect to what we did and what

7 it represents. Appreciate that comment.

8 And in terms of the mechanics of how we

9 got the results, here is that word again. Let's

10 everybody ignore the first two words. For the SOARCA

11 project we had, on the left, basically the one

12 deterministic value for all of the parameters that we

13 plug into the MELCOR model and got a source term. So

14 one source term signature in terms of timing and

15 release over time.

16 And then the MACCS model, we had one value

17 for all of the MACCS parameters. We took the source

18 term, plugged in all of the deterministic point values

19 for the MACCS and then the MACCS code was run

20 approximately 1,000 times in order to account for the

21 weather uncertainty.

22 So what you get out of the deterministic,

23 what we're calling the deterministic run, is actually

24 a distribution of results which represent the

25 uncertainty due to weather. That's the curve that you
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1 see on the left side at the bottom.

2 MEMBER CORRADINI: Can I say it back to

3 you differently?

4 DR. GHOSH: Yes.

5 MEMBER CORRADINI: So for every single

6 calculation of a vector of parameters you do a 1,000

7 weather calculations.

8 DR. GHOSH: That's right.

9 MEMBER CORRADINI: So you do a 1,000 times

10 900 if they're all successful.

11 DR. GHOSH: That is exactly right. Yes.

12 MEMBER BANERJEE: For this Y, typically

13 how large is that Y? Is it just the class of the

14 weather? The wind speed? Stratification? Is it a

15 large number of parameters or is it just the Pascal

16 class and the wind speed?

17 DR. GHOSH: For the weather parameters,

18 it's only five or six variables. And these are based

19 on for a given plant you get the weather data from the

20 weather station. I guess they call them the --

21 MEMBER BANERJEE: Direction, wind speed,

22 a few things like that.

23 MEMBER RYAN: Stability class.

24 MEMBER BANERJEE: Stability class, right.

25 DR. GHOSH: It's only a handful of things.
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1 And then basically the approach we took which is

2 fairly standard, we binned the weather into similar

3 categories in terms of how much rain and so on. In

4 this case we used about 1,000 weather trials from that

5 year of data because that would capture the statistics

6 of the differences.

7 And I'll talk later. To make sure that

8 that was good enough, we also used all of the data

9 points from that year. It turns out 1,000 is good

10 enough.

11 MEMBER CORRADINI: So I have probably an

12 incorrect view of this and you'll correct me. That's

13 one way to do it. Another way to do it is to pick a

14 multi year span and randomly pick a real time and do

15 a hindcast of real time. Do you get about the same

16 result?

17 In other words, if I picked two years and

18 I did 24 calculations by just binning 24 picks over

19 two years of real weather, would I end up getting

20 about the same thing as 1,000? Same sites. Forget

21 about the sites. But I actually went backwards in

22 time and said "In the last two years at Peach Bottom

23 I had this weather. And out of those two years I'm

24 going to pick a real weather hindcast here and another

25 here and another here and look at those 24 versus
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1 1,000 that are forecasts. Do you know what I'm

2 asking?

3 DR. GHOSH: Yes. Are you asking if we

4 only did 24 trials?

5 MEMBER CORRADINI: I'm asking is there

6 another way to do this that's more representative of

7 whether we've actually seen it at the site versus a

8 forecast.

9 DR. GHOSH: Okay. The forecast, maybe I

10 didn't explain that.

11 MEMBER CORRADINI: No, I think you

12 explained that well.

13 DR. GHOSH: We are using the real weather

14 at the Peach Bottom site.

15 MEMBER STETKAR: That 8760 points.

16 DR. GHOSH: Yes.

17 MR. BARR: From the year 2005.

18 MEMBER STETKAR: You have 8760 points.

19 MEMBER CORRADINI: Just one year of data.

20 (Simultaneous comments.)

21 MEMBER STETKAR: And your sample is a

22 start point. 

23 DR. GHOSH: Exactly.

24 MEMBER STETKAR: So it's 12:00 noon on

25 February 18th.
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1 MEMBER CORRADINI: Okay. So you use 1,000

2 hindcast. Okay.

3 MEMBER STETKAR: And the next 48 hours.

4 DR. GHOSH: Forty-eight hours, exactly.

5 MEMBER CORRADINI: I misunderstood that.

6 MEMBER STETKAR: It's only from one year.

7 DR. GHOSH: It's from one year.

8 MEMBER STETKAR: So you don't get like a

9 10 year variability and the extremes of the weather.

10 MEMBER CORRADINI: Okay. That's fine.

11 DR. GHOSH: In the past we have looked at

12 the year-to-year variation and it's on the order of

13 10, maybe 20, percent depending on the site. It's not

14 a huge compared to all the other uncertainties that go

15 into the analysis.

16 MEMBER CORRADINI: Thank you. That helps.

17 I guess I missed that. Sorry.

18 MEMBER STETKAR: Times the 20 percent

19 starts to add up after a little while though.

20 MEMBER BLEY: The risk comes from that 20

21 percent.

22 MEMBER STETKAR: The risk tends to come

23 from the 10 percent here and the 10 percent there.

24 DR. GHOSH: It all has to do with if you

25 have the 20 percent lined up in the same direction
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1 versus --

2 MEMBER STETKAR: It would be a little

3 probability but it's not zero.

4 DR. GHOSH: For each of the realizations

5 and also for the point estimate we get a distribution

6 that's the weather and a distribution from the

7 weather. Then for the uncertainty analysis what we

8 added now is that instead of one MELCOR source term,

9 we ended up with -- In this case it was 865 source

10 terms. We had 35 that for really numerical simulation

11 it would have taken too long for us to wait for the

12 MELCOR run to finish. So we just kind of aborted

13 them. And because we used the simple Monte Carlo

14 sampling that's okay. And we don't mess up our

15 statistics.

16 In that case, we had 865 source terms.

17 And for each of those 865 source terms, we took one

18 sample, one vector of sample values for all our MACCS

19 uncertain parameters. So that now goes in. And for

20 each of those we again did about 1,000 weather trials.

21 So we ended up with 865 curves that each curve in

22 essence represents the weather uncertainty.

23 But we did is --

24 MEMBER STETKAR: Wait, wait. Hold on a

25 second. Let me stop.
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1 DR. GHOSH: Sure.

2 MEMBER STETKAR: Because I --

3 MEMBER CORRADINI: I was waiting for you

4 to stop her.

5 MEMBER STETKAR: No. I really need to

6 understand this process. And I'm going to get to

7 MACCS in a second, but what you just said is what I

8 read in words. But it's not what I heard what you

9 explained mathematically. So let me take one MELCOR

10 realization. We've got 865. One.

11 DR. GHOSH: Yes.

12 MEMBER STETKAR: One run of MELCOR.

13 DR. GHOSH: Right.

14 MEMBER STETKAR: How many results does

15 that one run produce when you combine MACCS and the

16 weather?

17 DR. GHOSH: So there are two answers to

18 that.

19 MEMBER STETKAR: No. I want one answer.

20 I want how many. It's going to be either 984 or one.

21 And I want to know which of those two answers.

22 DR. GHOSH: For the purposes of the

23 report?

24 MEMBER STETKAR: No. I want to understand

25 how you did it. I want to understand how the math was
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1 done.

2 DR. GHOSH: We have the entire curve. So

3 we did 984 for each source term.

4 MEMBER STETKAR: Okay.

5 DR. GHOSH: We have a curve for each

6 source term.

7 MEMBER STETKAR: Over the weather.

8 DR. GHOSH: Over the weather.

9 MEMBER STETKAR: Good. Thank you.

10 DR. GHOSH: But what we report is the mean

11 value.

12 MEMBER STETKAR: Okay. I don't want to

13 get to the report because I need to understand what

14 was done first.

15 DR. GHOSH: Sure.

16 MEMBER STETKAR: So I understand what you

17 did with the weather which is good.

18 MEMBER CORRADINI: Wait a minute. Can we

19 get that on the record?

20 MEMBER STETKAR: No, that's good. 

21 MEMBER CORRADINI: Okay.

22 MEMBER STETKAR: But why did you only take

23 one sample for each MACCS input parameter for that one

24 MELCOR realization?

25 DR. GHOSH: Yes. The thing is we wanted
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1 to do an integrated analysis to see which set of

2 variables was also most important to the health

3 consequences. They're not just for the source term.

4 MEMBER STETKAR: I hear you saying those

5 words. I want to understand mathematically why you

6 only took one sample from each MACCS input parameter

7 for that realization.

8 DR. GHOSH: Right. So let's say that we

9 didn't have MELCOR and MACCS. If we had one

10 megamodel.

11 MEMBER STETKAR: Right.

12 DR. GHOSH: We could have modeled

13 everything.

14 MEMBER STETKAR: Right.

15 DR. GHOSH: We would have just had one

16 epistemic variable vector.

17 MEMBER STETKAR: And I don't want to use

18 the word epistemic. Just sample.

19 DR. GHOSH: Yes, one sample value for each

20 uncertain variable across the metric.

21 MEMBER STETKAR: Amen. And you might have

22 needed 10 million samples to get convergence.

23 MEMBER CORRADINI: How do you know that

24 you needed so many more than 865?

25 MEMBER STETKAR: I know that 865 is not
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1 enough.

2 MEMBER CORRADINI: How do we know that?

3 MEMBER STETKAR: Because we know how

4 uncertainty distributions combine when they're broad,

5 skewed uncertainty distributions. We know this from

6 experience.

7 DR. GHOSH: Yes.

8 MEMBER STETKAR: We've reasonably captured

9 -- Let me cut to the quick here because we only have

10 an hour and a quarter. We've reasonably captured the

11 uncertainty perhaps depending on what you define as

12 reasonable in MELCOR within about plus or minus 20

13 percent convergence which is not all that reasonable.

14 We've not at all captured the uncertainty in MACCS.

15 And let me just give a simple example.

16 Single realization from MELCOR. Let me take a

17 parameter called e speed, evacuation speed, of the

18 populace. The populace evacuation speed doesn't

19 depend at all on the what the release category is. So

20 I should have an uncertainty distribution in

21 evacuation speed for that single realization. Right

22 now, I have a single value. 

23 MEMBER CORRADINI: But can I make the same

24 argument within the severe accident? I can make the

25 same argument that ex-vessel phenomena have nothing to
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1 do with in-vessel phenomena. Therefore, I have to

2 have a single realization come out of the ex-vessel

3 and a handful of --

4 MEMBER STETKAR: There at least they are

5 sampling and looking at the convergence of the results

6 from MELCOR and making arguments that 865 was good

7 enough to reach reasonable convergence on the

8 uncertainties and the output parameters that they were

9 interested in.

10 MEMBER CORRADINI: But your argument --

11 MEMBER STETKAR: So the in-vessel/ex12 vessel stuff is all tied up in there.

13 MEMBER SHACK: Let me try it a different

14 question. John is arguing that -- I think he would

15 agree that if you took enough samples if your approach

16 would work. How do you convince yourself with 865

17 samples you've got reasonable convergence?

18 DR. GHOSH: We documented our convergence

19 analysis in the report. What we did -- It's okay. I

20 mean you may not like what we did. Let me explain what

21 we did.

22 MEMBER SHACK: We want to know what you

23 did.

24 DR. GHOSH: We originally had started with

25 a sample size of 300, not because -- Of course, I
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1 would have loved to do 10,000 but you know. Nine

2 hundred we do think is a reasonable amount. But we

3 started originally with 300.

4 What we did was we ended up doing three

5 replicates of 300. So we did a MACCS analyses with

6 three MELCOR replicates of 300. So we have three

7 separate uncertainty analyses in essence with the

8 sample value of 300.

9 Then we also took the super sample. We

10 ended up having 865. We took the super sample and

11 also did the statistics there. So we have four sets

12 of statistics for the MACCS results. We have the

13 three replicates of 300 each. I mean it actually

14 comes out to on average 290, 280 something and the

15 super set of 865.

16 And then we compared how much variance

17 there was in the statistics we turned, the mean, the

18 median.

19 MEMBER STETKAR: Let me stop you there.

20 So far you've described convergence of the MELCOR

21 sampling and I understand what you did there. I might

22 disagree with the 20 percent is reasonable. But I

23 understand.

24 So far you've not discussed at all

25 convergence, the integrated MELCOR/MACCS weather
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1 sampling. You've not discussed that at all.

2 DR. GHOSH: Okay.

3 MEMBER STETKAR: So we're interested in

4 how do you demonstrate that you've taken enough.

5 Think of a single -- that was a good way -- integrated

6 MEL/MACCS weather model that if you had that fully

7 integrated model that 865 samples are adequate to

8 reach convergence if I did a full Monte Carlo sampling

9 of that integrate model. An adequate convergence of

10 the results of that integrated model, not just the 900

11 and 300, 300 and 300 MELCOR stuff. I understand what

12 you did there.

13 So think through all the way through to

14 the end.

15 DR. GHOSH: Yes, I understand. I don't

16 think 865 is a bad number and for the following

17 reason. Again, we did the three replicates and when

18 you compare across the replicates and with the super

19 sample, our statistical measures don't vary that much.

20 MEMBER STETKAR: MELCOR. Okay.

21 DR. GHOSH: No, no. For the health

22 consequence they vary like 10 percent.

23 MEMBER STETKAR: Okay. But let's take a

24 situation where your sampling from MACCS always gave

25 you the same input. You're only selecting one. Then
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1 you'd see the results and the convergence from your

2 integrated MEL/MACCS just replicate the uncertainty in

3 MELCOR.

4 And if I look at in the study the

5 uncertainty in the MELCOR results it's roughly a

6 factor of about 50 -- fifth to the 95th. If I look at

7 13, 14, if I look at the results from your integrated

8 analysis with MELCOR, MACCS and the weather, it's

9 roughly the same range which says I'm not adding any

10 uncertainty from all of that weather and MACCS which

11 bothers me a lot.

12 DR. GHOSH: Yes. So that's the second

13 piece of the puzzle which is why we think that 865 is

14 enough. There is actually a pretty strong dampening

15 effect when you go from the source term to the health

16 consequence because the long-term phase is what's

17 dominating the risk. And you have a back stop against

18 how much LCF risk you can impart on people because

19 you're evacuating them if there's too much radiation

20 there. There's too much contamination there. And

21 they're not allowed to come back until for Peach

22 Bottom you get below the habitability criterion of 500

23 millirem per year.

24 So that's why in fact you see that the

25 source term variance is larger than the LCF risk
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1 variance because you have this dampening effect

2 between the source term and the health consequence.

3 MEMBER STETKAR: Is that dampening effect

4 though an artificial product of the way that you did

5 your limited sample?

6 DR. GHOSH: I don't believe so. I mean I

7 think phenomenalogically we can explain that.

8 The other thing I just want to point out

9 is there are a lot of uncertain parameters in MACCS.

10 But it turns out there is really only a handful that

11 really only drives the uncertainty and the results.

12 So on face value when you look at the number of

13 parameters it sound like 865 there's no way that that

14 could be enough. But the vast majority of them don't

15 make a very significant contribution to the

16 uncertainty and the results.

17 So I think when you then evaluate how many

18 parameters are really driving the variance and you see

19 the 865, you then can also consider that there is this

20 dampening effect between the source term and the

21 health consequence. And we did the convergence

22 analyses with the three replicates and the 865. 

23 We can never say definitively without a

24 doubt that this is absolutely correct. But we feel

25 fairly confident in terms of convergence.
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1 MEMBER STETKAR: Did you ever take a

2 single, a couple -- it's dangerous to take one -- but

3 two or three MELCOR replicates that would kind of

4 drive in the consequence analysis like a late SRV

5 failure with an early battery failure or something

6 like that? You know select a couple. And then run

7 the weather and MACCS with a false sampling of all of

8 the input parameters and see what that distribution

9 looked like for each of those runs. Did you ever do

10 that?

11 DR. GHOSH: We haven't done that yet. But

12 I think we can recreate something like that because we

13 have so many source terms that are within a -- With

14 865 realizations we can go back to our results and

15 kind of look at the range of MACCS results. But we

16 could do that.

17 MEMBER STETKAR: But you'd need to change

18 the way you do the sampling. I mean you would need to

19 take that one MELCOR replicate and actually do N

20 samples of all of the MACCS input parameters. You'd

21 need to change your sampling algorithm now. And then

22 examine convergence, how many samples, what does the

23 shape of that distribution look like, how broad is it.

24 And how many samples from MACCS and

25 weather since they're integrated does it take to get
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1 convergence in that distribution? That would be a

2 real confidence builder. If that distribution was

3 really narrow, that would be a confidence builder.

4 MEMBER CORRADINI: Narrow compared to

5 what?

6 MEMBER SHACK: The distribution they now

7 get.

8 MEMBER CORRADINI: That's what I thought

9 you were getting at.

10 MEMBER STETKAR: No, this is not the

11 distribution for the overall results.

12 (Simultaneous comments.)

13 No. Well, for latent cancer fatalities or

14 whatever the consequences are.

15 MEMBER CORRADINI: But I guess I'd agree

16 with what you're asking them to do if you were saying

17 is the spread here within the spread they got from

18 that.

19 MEMBER STETKAR: No. This is lighter.

20 MEMBER CORRADINI: If the spread is wider

21 in that worries me.

22 MEMBER STETKAR: What do you mean if the

23 spread is wider?

24 MEMBER CORRADINI: I mean I'm just picking

25 something that -- Let's pick land interdicted. If the
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1 land interdicted spread from their 865 by this

2 integrated approach is here and they took one

3 realization from MELCOR and did like one billion,

4 whatever the necessary number you feel comfortable

5 with, and they're spread from just MACCS alone within

6 that, then I'd say their 865 is --

7 MEMBER STETKAR: No because that

8 uncertainty -- It depends on how broad that

9 uncertainty is, Mike. Everything is driven by tales

10 of the distribution. So if you're artificially

11 constraining the results -- 

12 If you're looking at the uncertainty in

13 MELCOR only and presuming that the uncertainty in

14 MACCS is small then the uncertainty that you see will

15 be the uncertainty in MELCOR. If the uncertainty in

16 MACCS is large, the uncertainty in the results is

17 going to be the compound of that.

18 MEMBER CORRADINI: But you have to compare

19 it something to know.

20 MEMBER STETKAR: All I'm asking them to do

21 is to take two or three MELCOR realizations and do

22 essentially what they did for MELCOR, run N where N is

23 big enough samples of the MACCS input distributions

24 and the weather and look at what the distribution of

25 latent cancer fatalities are for that single run.
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1 MEMBER CORRADINI: I understand.

2 MEMBER STETKAR: That will give you a

3 sense of how big the spread is from MELCOR from MACCS.

4 MEMBER CORRADINI: So they see the spreads

5 and then they've got to compare it to something.

6 MEMBER SCHULTZ: No they have to -- in

7 order to validate.

8 MEMBER STETKAR: What they're comparing it

9 is they only have a single value the way they're doing

10 it right now. They have a single value.

11 MEMBER SCHULTZ: Tina gave a description

12 of why she felt comfortable about the way it had been

13 done so far.

14 MEMBER STETKAR: And if the results of

15 those would be small then I'd feel a lot more

16 comfortable.

17 MEMBER CORRADINI: Small compared to what?

18 MEMBER SHACK: Let me try my shot at that.

19 I think what they've done is they've now got the

20 combined MACCS/MELCOR epistemic uncertainty by their

21 approach. They think they've got a converged answer.

22 I think what John is asking is to look at

23 the MACCS epistemic uncertainty. And again you've got

24 the epistemic uncertainly in MELCOR alone because

25 you've got the 865 samples. 
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1 So you've got MELCOR alone. You've got

2 MELCOR/MACCS combined. He wants to see MACCS

3 identified. And I think the fair comparison with the

4 uncertainty that you have in the combined MACCS/MELCOR

5 uncertainty.

6 MEMBER CORRADINI: That's got to be a

7 comparison. Otherwise you're not going to know what

8 to compare to.

9 MEMBER STETKAR: You can't think about

10 uncertainty and evacuation speed for this particular

11 source term in terms of the composite uncertainty and

12 evacuation speed -- I'm just picking that as one

13 variable -- over the full range of source terms.

14 I mean obvious -- It's not obvious. If

15 the uncertainty in the latent cancer fatalities for a

16 specific realization for MELCOR was much larger than

17 the overall uncertainty and results, that would be

18 really condemning. I wouldn't expect it to that bad.

19 MEMBER CORRADINI: I understand what

20 you're asking them to do. I think I get that. I

21 understand what you're asking them to do. But I'm not

22 understanding what criteria you're going to put on

23 that result to decide it's converged.

24 MEMBER STETKAR: You can determine whether

25 the results are converged. That's just a sampling
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1 criteria.

2 MEMBER SHACK: They think their results

3 have converged now.

4 DR. GHOSH: We think that we converged.

5 MEMBER SHACK: Right.

6 DR. GHOSH: Can I --

7 MEMBER STETKAR: Dennis, you helped.

8 MR. BARR: I think what John is suggesting

9 would be an extremely valuable result.

10 DR. GHOSH: Sure.

11 MEMBER SCHULTZ: I mean you described why

12 you felt and why you concluded that the distributions

13 in MELCOR are as they are and in comparison to the

14 total which are similar. You described why you feel

15 that's appropriate given what you speculate would be

16 the result of the evaluation that John is describing.

17 If you can demonstrate that you have

18 validated your thoughts about it. And those

19 conclusions I think are going to be very important

20 about offsite consequence analysis. Very important

21 conclusions about it that we haven't fully validated.

22 MEMBER SHACK: Let me just ask another

23 techie question again. You examined the convergence

24 in the MELCOR sampling by bootstrapping the final

25 result. Why didn't you do that for the combined one?
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1 DR. GHOSH: Yes. It's a good question.

2 You know we used the Latin hypercube sampling for the

3 MACCS runs because we don't have the same issue we had

4 with MELCOR. The MELCOR we knew that some of the runs

5 wouldn't run to completion within a reasonable amount

6 of time. And we kind of had to abort them because

7 they would take a year to converge or something.

8 MACCS doesn't have that same problem. We

9 felt that Latin hypercube sampling is the preferred

10 method usually going in. After this conversation,

11 I'll have to re-evaluate that. But usually we say

12 that with Latin hypercube sampling we get a better

13 estimation of the tales of the distribution which is

14 why Latin hypercube sampling is usually preferred.

15 So for the MACCS we used Latin hypercube

16 sampling. But once you do that, you can't use the

17 same bootstrapping method that we used for the MELCOR

18 results which use simple random sampling and where we

19 could use the distribution.

20 MEMBER SHACK: But when you've got the

21 final distribution can't you bootstrap off of that

22 because it's just a distribution at that point whether

23 you got it by simple random sampling or Latin

24 hypercube?

25 DR. GHOSH: Yes, I think --
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1 MEMBER SHACK: When you use the T

2 distribution that somehow builds in so much

3 presumption about the shape of the distribution.

4 DR. GHOSH: Yes. I'll tell you what. Let

5 me take it as a homework assignment to re-evaluate

6 what else we could do. And I also understand the

7 suggestion.

8 MEMBER SHACK: One more question on the

9 mechanics and that is --

10 DR. GHOSH: Yes.

11 MEMBER SHACK: You've done the one MELCOR

12 sample, the one MACCS sample, the 984 aleatory.

13 DR. GHOSH: Yes.

14 MEMBER SHACK: You then average the

15 aleatory once for each of those because you're

16 isolating an epistemic uncertainty. And that's really

17 what you're presenting in the report.

18 DR. GHOSH: That is exactly right. So the

19 distributions we'll talk about later, they are the

20 distributions of the means from --

21 MEMBER SHACK: The aleatory runs.

22 DR. GHOSH: Right. Exactly.

23 MEMBER STETKAR: Why did you do that?

24 Because now I understand better -- No, I actually

25 understand. That is good that you actually run all
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1 984 weather samples. But when you presented the

2 results, why didn't you capture that uncertainty in

3 the weather? In other words, actually convolute those

4 distributions for the results rather than just taking

5 effectively the mean of the weather multiplied by each

6 of the other realizations?

7 DR. GHOSH: Right. I mean we were trying

8 to be consistent with the SOARCA project. But one

9 thing in terms of the metrics that we report. But let

10 me offer this.

11 One thing we did do and this is in part

12 sparked by both questions from the SOARCA peer review

13 committee as well as the ACRS is we looked at

14 comparing the contribution from the weather

15 uncertainty compared to the epistemic uncertainty. So

16 we took particular source terms that were

17 representative of kind of like a low/medium/high and

18 then looked at the spread and the uncertainty from

19 weather versus the epistemic uncertainty from all of

20 the trials to get some sense of the relative effects

21 of weather versus the epistemic uncertainty.

22 And I'm actually going to talk about -- if

23 I get to it -- that later today. So we did do that.

24 MEMBER STETKAR: Reading the words is

25 difficult to find out what you did.
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1 MEMBER SHACK: When you did that single

2 replicate, you did that one only again with one MACCS

3 sample. I would have found that one much more

4 comfortable if you would have had the single MELCOR

5 source and then did a number of MACCS replicates and

6 the weather.

7 MEMBER STETKAR: And the weather.

8 DR. GHOSH: For the aleatory weather,

9 okay. Point taken. I think I understand.

10 MEMBER STETKAR: By the way, I think the

11 study uses the terms "epistemic" and "aleatory" as if

12 they are purely defined. And indeed they're not. The

13 vast majority of things have contributions from both

14 aleatory and epistemic. I'll grant you weather is

15 aleatory.

16 DR. GHOSH: Right.

17 MEMBER STETKAR: To my mind, it dunnit

18 make any difference and that's done with no S because

19 I'm trying to make a point here. It dunnit make any

20 difference whether I have epistemic or aleatory

21 uncertainty when I'm combining those uncertainties.

22 It does when I look back and try to

23 understand how I might reduce that uncertainty because

24 I'm --

25 MEMBER BLEY: Depending on how you
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1 generate them, it can have a big difference on the

2 shape you applied of what those distributions look

3 like.

4 MEMBER STETKAR: That shapes of the

5 distributions. But in the mechanics of the process I

6 ought not to think of method X of combining aleatory

7 uncertainty and method Y of treating epistemic

8 uncertainty.

9 MEMBER BLEY: Can I sneak in a comment?

10 Something that would be really helpful would be to

11 make a bed sheet 11 by 17 foldout with a map of the

12 arithmetic you do and right up front. So you look at

13 that and see what's coming and how you did all of

14 this.

15 MEMBER CORRADINI: For the techies. Not

16 for the general public.

17 MEMBER BLEY: Yes. Most of this report is

18 not for the general public.

19 MEMBER STETKAR: This is not a general

20 public report.

21 MEMBER BLEY: No.

22 DR. GHOSH: Yes, we'll do that. I think we

23 attempted to do that in a simplified diagram. But I

24 take your point. We can do that.

25 MEMBER BLEY: And the other question I had
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1 and it's been asked before I didn't hear an answer I

2 really understood as to why you only took a single

3 sample from each source term. Why didn't you multiply

4 sample?

5 DR. GHOSH: And again --

6 MEMBER BLEY: Is that explained somewhere

7 because I couldn't find anything I understood?

8 DR. GHOSH: No. I think this goes back to

9 the reason we had to do the MELCOR and the MACCS

10 separately is because we don't have a megamodel of the

11 whole.

12 MEMBER BLEY: I got that.

13 DR. GHOSH: If we had a megamodel of the

14 entire model we would do exactly what we did here

15 which is you only take one vector of all the

16 uncertainties. Because we have two separate models,

17 we have the flexibility to look at them separately.

18 But we did not do that because again theoretically if

19 we had had a mega model which is what we were after to

20 look at the relative contributions of the

21 uncertainties with the entire system together with

22 respect to the health consequences you would only take

23 one vector at a time.

24 MEMBER CORRADINI: Can I ask a question?

25 If you had the mega model and 900 is not enough for
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1 his warm feeling of convergence, is 1800 enough? Does

2 anybody know statistically what it is?

3 MEMBER STETKAR: Yes, there are normal

4 ways approximately for this point.

5 MEMBER BLEY: You don't know.

6 MEMBER STETKAR: That's the thing. You

7 don't know.

8 DR. GHOSH: Yes.

9 MEMBER BLEY: It's an algorithm to look at

10 your results. It's not --

11 MEMBER CORRADINI: So you keep on checking

12 by subdividing the sample and see if you're got it. 

13 I wouldn't say it that way but you could say yes.

14 MEMBER STETKAR: If you want to think of

15 it.

16 MEMBER SHACK: You're looking at multiple

17 samples, yes.

18 MEMBER STETKAR: As you take more samples,

19 the convergence should narrow.

20 DR. GHOSH: Right.

21 MEMBER CORRADINI: Okay.

22 MEMBER STETKAR: It doesn't necessarily --

23 MEMBER CORRADINI: So you're saying -- So

24 my question then becomes how much is enough.

25 MEMBER STETKAR: You typically set your
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1 own convergence limits. You say that you want to feel

2 comfortable if my mean value is converged to within

3 ten percent or two percent or 20 percent.

4 MEMBER CORRADINI: Okay. I thought that

5 where you were going. But you don't feel comfortable

6 with 20 percent which is what they're seeing.

7 MEMBER STETKAR: I'm not trying to

8 address that issue.

9 MEMBER CORRADINI: I understand that. But

10 they may feel comfortable and you don't simply because

11 on what you want to see as the final convergence

12 value.

13 MEMBER STETKAR: Right. Because some of

14 the 20 percent that they're missing for example may be

15 part of that tail that wags the dog if we were doing

16 the full sample out through MACCS. But first I'd like

17 --

18 MEMBER CORRADINI: I'm happy.

19 MEMBER STETKAR: -- to have a better

20 understanding of what they did.

21 DR. GHOSH: Let me also offer one last

22 thing and then hopefully we can get back to my slide

23 eight of my presentation. You know doing the 865 and

24 we can disagree about whether or not we think that's

25 enough we did see quite a range of behavior.
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1 And in looking at the early fatality

2 consequence values, that was purely a model

3 verification exercise. There were so few none zero

4 results and we analyzed the outliers. And we got some

5 real tale behavior and I'll talk about that. And it's

6 in the single realization analyses.

7 So that's another thing. It's a

8 combination of what specifically we would do but also

9 phenomenalogically if we're seeing that range of

10 behavior and some new things that we haven't seen

11 before.

12 MEMBER STETKAR: I mean it's fortunate in

13 some sense that you did take enough samples that you

14 at least saw that because it sort of alerted you to

15 the fact that there might be things going on that you

16 hadn't thought about before just from the base case

17 for example.

18 DR. GHOSH: Right.

19 MEMBER SHACK: One last comment. One of

20 the reasons I think that gets so confusing is the word

21 "mean" shows up so many times. We have mean cancer

22 fatality. But you have that for individual runs. You

23 have that for the combined aleatory runs. You have

24 that for the combined epistemic runs.

25 If you could sort of go through and define
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1 what you were averaging through each set of figures I

2 think it would reduce the confusion. I know John and

3 I both had a hard time figuring out exactly what you

4 were doing.

5 DR. GHOSH: Yes. I appreciate that. We

6 just finished writing a set of conference papers and

7 oh my gosh. Our table titles were like five lines

8 long to be able to explain exactly what's shown in the

9 table. Yes, I appreciate that.

10 And perhaps a figure such as Dr. Bley is

11 suggesting would help. We'll take a stab at that.

12 If we could go back to slide eight. If

13 there are no more questions on the mechanics I hope.

14 Right?

15 MEMBER SCHULTZ: At this time.

16 DR. GHOSH: At this time, okay. Good. So

17 we'll talk about the results first. First, this is

18 the MELCOR results. It's the source term. And we

19 focused on cesium and iodine initially. And this is

20 because cesium in essence drives the long-term health

21 risks and iodine is, of course, traditionally a

22 significant contributor to early or prompt fatality

23 risk where there is an earlier prompt fatality risk.

24 But just a little side note, I think for

25 future work we'll probably look at additional
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1 radionuclide groups as well. It turns out that cerium

2 is important, the cerium group is important, in some

3 cases. So I think in future work we're certainly

4 going to take a closer look at that.

5 MEMBER CORRADINI: Why is that? I don't

6 think I know why.

7 DR. GHOSH: While the long-term phase

8 dominates the written cancer fatality risk, in some of

9 the realizations you do have a significant

10 contribution from the plume going overhead once you

11 get past the 10 mile EPZ, emergency planning zone. So

12 the cerium group from the plume going overhead makes

13 a more substantial contribution.

14 MEMBER CORRADINI: And the assumption is

15 that outside the ten miles nobody moves.

16 DR. GHOSH: No, no. It's not that nobody

17 moves. You don't have the automatic evacuation, but

18 you have hot spot, what's called hot spot, in normal

19 relocation.

20 MEMBER CORRADINI: Okay.

21 DR. GHOSH: But there are more people

22 exposed. They may be small doses, but you still have

23 more people exposed.

24 MEMBER CORRADINI: Okay. Thank you.

25 MEMBER BLEY: Can I make a presentation
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1 suggestion?

2 DR. GHOSH: Sure.

3 MEMBER BLEY: There are many other places

4 where we regenerate spaghetti curves and then somehow

5 untangle it and come up with the confidence curves.

6 Nobody needs to see all the work you did to come up

7 with spaghetti curves anymore. It's more confusing

8 than helpful I think.

9 DR. GHOSH: Okay.

10 MEMBER BLEY: And nobody does it anywhere

11 else. Once you've done that you can put an order to

12 it. It's just confusing I think after that.

13 DR. GHOSH: Okay, sure. So you're

14 suggesting just keep the statistics.

15 MEMBER BLEY: Get rid of the gray stuff.

16 DR. GHOSH: Keep the statistics curve and

17 not -- You know I came from the Yucca Mountain world.

18 We love the horsetail graphs. And a lot of my team

19 are also from former Yucca Mountain folks. But point

20 taken.

21 MEMBER SHACK: Understand something. I

22 like the horsetails. 

23 MEMBER BLEY: There are lots of places you

24 could see them in other analyses where they finally

25 got rid of them because they really cause people
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1 trouble.

2 MEMBER SHACK: I think they give you a

3 real picture of --

4 MEMBER BLEY: What the world looks like.

5 MEMBER SHACK: -- what the world looks

6 like.

7 MEMBER BLEY: They do. But I think they

8 cause more confusion than value.

9 MEMBER STETKAR: In many cases in this

10 report, the understanding of the underlying messages

11 gets absurd a bit by the vast numbers of numbers that

12 are cited. And the horsetail plots is an example of

13 that. All of those other citations of large numbers

14 of numbers are difficult.

15 MEMBER SHACK: Means are what confuse me.

16 MEMBER STETKAR: Single value means is

17 what confused me. But that's okay.

18 DR. GHOSH: I apologize. We had competing

19 objectives of being as thorough as possible for

20 posterity versus clarity. But I understand.

21 So the only point for this one is that --

22 I'm sorry. Can you go back just a minute? This was a

23 subset of scenarios that had early stochastic

24 failures. They are the ones that are most similar to

25 the SOARCA project's projection. And that's why this
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1 curve is shown. 

2 And also just to give you an idea. The

3 colored dashed lines are examples of what we call the

4 single realizations that we looked at to analyze in

5 detail so that we could see what was driving different

6 ranges of behavior. The next slide.

7 This is now the entire set of 865 which

8 includes also the main steam line creep rupture cases

9 as well as the weight SRV thermal failures without

10 main steam line creep rupture.

11 You have a question.

12 MEMBER CORRADINI: I have a question but

13 it's modeling. And I've been ruled that I'm out of

14 order if I ask it.

15 DR. GHOSH: Okay. The next slide. The

16 next slide we have the iodine results. 

17 MEMBER STETKAR: I think we've already

18 decided we're going to have another subcommittee

19 meeting. And I think we need to explore those issues

20 at that meeting.

21 MEMBER CORRADINI: Yes, sir. You got your

22 half an hour. That's okay.

23 (Laughter.)

24 MEMBER CORRADINI: That's on the record.

25 I'm sorry. Forty-five minutes.
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1 MEMBER STETKAR: I'll get another ten in

2 the next brief.

3 MEMBER CORRADINI: You're the vice

4 chairman. You have the power.

5 MEMBER SHACK: We haven't even started

6 discussing this in the Committee forum yet.

7 DR. GHOSH: So slide 11 is the MACCS

8 results. And again this is the statistics on the

9 means from the weather trials. So this is the

10 distribution of the means.

11 These are the conditional results. And

12 just as a reminder the scenario frequency we had going

in for long-term station blackout was about 3 X 10-6 13 .

14 MEMBER STETKAR: Tina, is there a real --

15 You keep trying to make SOARCA a PRA. Why do you need

16 to keep -- No, you do because there are many places in

17 this report where you keep coming back to that

18 frequency and comparing it to the quantitative health

19 objectives with caveats saying "Yes, we only looked at

20 one sequence and the numbers are small."

21 But indeed especially in this report,

22 there is no reason to do that. This is literally the

23 uncertainty and conditional consequences.

24 DR. GHOSH: Okay.

25 MEMBER STETKAR: And I think especially
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1 whenever -- Granted that this is a techie report and

2 it's not necessarily for public consumption. But

3 indeed it's a publicly released report. When the

4 public reads those things, they're not going to

5 appreciate all the nuances. They're only going to

6 show that the NRC did a comprehensive uncertainty

7 analysis that concluded that the risk from long-term

8 station blackout is so far below the quantitative

9 health objectives that we don't care about the risk

10 from nuclear power plants. That's what they're going

11 to conclude.

12 And we can't say that from this report.

13 We've not evaluated uncertainly in the frequency of

14 even that one scenario. We've not evaluated

15 uncertainty in the human reliability which we know

16 contributes very strongly, the three different actions

17 that are presumed in this scenario.

18 So I think that those comparisons with

19 absolute frequencies and especially comparisons with

20 the quantitative health objectives are not appropriate

21 especially within the context of this report.

22 DR. GHOSH: Okay.

23 MS. GIBSON: We still have to have

24 somewhere to give the public perspective. So if you

25 have suggestions.
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1 MEMBER CORRADINI: I have one way which is

2 if you want to do it on a relative basis like John has

3 said at least if I remember. It's been so long that

4 I can't remember how SOARCA started. But if I'm

5 remembering correctly Commissioner McGaffigan

6 basically suggested the 1982 study was way too

7 conservative. You might want to go back and simply

8 compare everything to the 1982 study.

9 I know some people around the Committee

10 would think I've lost it. But it just seems to me if

11 you want to do it on a relative basis that's what was

12 the genesis of this whole thing. I mean, am I

13 remembering correctly?

14 MEMBER SHACK: You're remembering

15 correctly. It's a bad idea.

16 MEMBER CORRADINI: Even though it's a bad

17 idea. I was waiting for you to say something.

18 MEMBER STETKAR: I'm not going on the

19 public record make suggestions about specifics. Let

20 me just reiterate. I think that especially in the

21 context of this report extending it to make any type

22 of conclusions about absolute risk in terms of

23 frequency and consequences is not appropriate. And

24 it's especially not appropriate when you make

25 comparisons against quantitative health objectives
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1 which apply for the full risk from that nuclear power

2 plant, not even the risk from one scenario. Just take

3 that.

4 MEMBER CORRADINI: But then on the other

5 hand none of us agree with each other.

6 DR. GHOSH: If we could go to the next

7 slide. Again, this is the prompt fatality risk and

8 you can see that once you get beyond 2.5 miles there

9 is only a handful of realizations that you get in non

10 zero resulted. Or the 95 percentile is zero even

11 though the median and 75th is across the board. But

12 there were 13 percent of realizations that calculated

13 non zero results.

14 Actually, this was nice. It was really a

15 model verification exercise. And we looked at some of

16 the single realizations where we got outlier results

17 and confirmed that if you have a really bad day and

18 all the stars align against you just right, you can

19 get a prompt fatality. So it was kind of a model

20 verification.

21 But when you look at overall the

22 statistics they are extremely small numbers. And you

23 would still say there is essentially no risk. But in

24 your worst case scenario, you can have some risk.

25 The next slide, slide 13, actually go
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1 straight into slide 14. I just want to point out what

2 are the most influential parameters in terms of the

3 source term magnitude. I think we talked about some

4 of this already last April. So this is probably more

5 for reminder.

6 There are a couple of parameters that come

7 together that really determine how your accident is

8 going to progress with regard to are you going to have

9 an early stochastic failure of the SRV which is kind

10 of your better set of scenarios with respect to

11 magnitude. Or is it going to fail later? And if it

12 fails later, whether you have main steam line creep

13 rupture.

14 So the SRV stochastic failure rate which

15 is the first one, it's a lambda. That's why it's

16 abbreviated SRVLAM. I just put in the abbreviations

17 here. It's probably not that important, but we also

18 use them in the report. They're connected to the

19 MELCOR variables.

20 That one along with the fourth bullet, the

21 fraction open area of the SRV, that's sampled in case

22 it fails to reseat because of thermal seizure. Those

23 two variables largely determine which way the accident

24 progression is going to go which is also a large

25 determinant of your eventual source term.
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1 MEMBER CORRADINI: So these far and away,

2 one and four are far and away from a model from an

3 uncertainty standpoint given a model assumed drives

4 the results.

5 DR. GHOSH: That's right. And the first

6 one really is the most important.

7 MEMBER CORRADINI: Then, two, three, five,

8 six, seven are like all in a kind of mush together.

9 DR. GHOSH: Yes. And they're also

10 important for different reasons. I'll just quickly go

11 through right now.

12 MEMBER CORRADINI: All right.

13 DR. GHOSH: The chemical form of cesium,

14 this one was a surprise. For the high temperature

15 scenario, cesium hydroxide ends up being beneficial

16 because you have chem absorption on the upper steel

17 components inside the vessel.

18 This model existed in MELCOR and we

19 checked after we saw this to see whether this is a

20 legitimate model. And it turns out that it seems that

21 people agree that it is. So we were kind of surprised.

22 We had expected that cesium hydroxide

23 would lead to larger releases. But in fact for the

24 larger source term scenarios like main steam line

25 creep rupture if you sample the cesium as cesium
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1 hydroxide it actually -- there is actually smaller

2 releases. It kind of counteracts how much you can get

3 out because of the chem absorption. 

4 And the cesium molybdate does not chem

5 absorb. So that still gets out. So that was an

6 interesting one. Which speciation is beneficial

7 depends on which accident progression subscenario that

8 you have.

9 MEMBER CORRADINI: So if the Committee

10 will allow. I guess I'm intrigued by this because my

11 first question is did your subject matter experts

12 resolve that this made sense because of what's going

13 on in PHOEBUS and what they prognosticated occurred at

14 Fukushima. How did you come to the conclusion? The

15 one person we'd ask is now declared himself ineligible

16 and he's gone.

17 DR. GHOSH: Yes.

18 MEMBER CORRADINI: But I'm very curious

19 about this.

20 DR. GHOSH: We could have talked to him on

21 the chem absorption model though. At least that is a

22 legitimate model in MELCOR.

23 So what we put in to it were the bins in

24 terms of the split between the hydroxide and

25 molybdate. That was based on the PHOEBUS experiments.
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1 But at the time, we did not have the latest PHOEBUS

2 results which showed that.

3 I think the consensus is now that probably

4 the best split is about 70 percent cesium molybdate

5 and 30 percent cesium hydroxide. We did not have that

6 result at the time of the uncertainty analysis. So

7 our bins are 50/50. All cesium molybdate or all

8 cesium hydroxide and then --

9 MEMBER CORRADINI: As terms of what it

10 could be.

11 DR. GHOSH: Yes. Exactly. So that's what

12 we put into it.

13 MEMBER CORRADINI: Okay.

14 DR. GHOSH: And then what we got out of it

15 is that you know which chemical form is more

16 beneficial in terms of releases depends on which

17 accident.

18 MEMBER CORRADINI: So that's my question

19 on the second bullet. Am I allowed a question on the

20 third bullet?

21 So there is an Oak Ridge/Sandia report

22 that went into gory detail about excessive phenomena

23 relative to Fukushima. And the conclusion from that

24 is the MELCOR model is wrong. Just wrong.

25 DR. GHOSH: Yes.
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1 MEMBER CORRADINI: Okay. And a side

2 model, an auxiliary model, that was used by Oak Ridge

3 and Sandia shows pretty much no dry well liner

4 failure. Was there some -- Maybe I missed it. Was

5 there somewhere where you essentially by a tale

6 excluded a dry well liner failure to see that effect?

7 I'm very curious of what that effect would be relative

8 to source term because it's not clear to me it's

9 conservative by having dry well liner failure?

10 DR. GHOSH: We did not change our models

11 after Fukushima happened. We didn't change our

12 scenario definition or the models. I'm sure as the

13 community learns more from Fukushima we'll be updating

14 things. But it wasn't part of this project.

15 MEMBER CORRADINI: Okay.

16 MEMBER REMPE: And in fact there was no --

17 Basically, if the debris leaves the vessel and

18 contacts the outer wall, it's assumed to fail. There

19 is no heat transfer analysis or anything that's

20 calculated is what I read in your report on page 96.

21 So there's not much of a model here.

22 MEMBER CORRADINI: And I won't criticize.

23 I just wanted to make sure that you -- I'm sure you

24 were aware of the Oak Ridge/Sandia work.

25 DR. GHOSH: The other thing is I think the
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1 ex-vessel modeling we're pursuing additional things in

2 MELCOR right now.

3 MEMBER CORRADINI: That's fine.

4 DR. GHOSH: But we use what we had in

5 existence.

6 MR. FULLER: This is Ed Fuller again. I'm

7 not sure I know exactly what the report that you're

8 referring assumes in terms of water on the floor when

9 the vessel is breached.

10 MEMBER CORRADINI: They assume basically

11 up to the pipes to the wet well. So about 12 to 18

12 inches of water.

13 MR. FULLER: Okay. But in this analysis

14 there is no water addition. So you've got basically

15 a dry pedestal and dry well floor.

16 MEMBER CORRADINI: Station blackout and

17 the pump seals don't fail and there's no water

18 leakage? I find that --

19 MR. FULLER: Well, there may be a little.

20 I don't know the details of these MELCOR cases because

21 we don't see them in detail. But what we're talking

22 about if anything is a very small amount of water

23 relative to what you'd be looking at in a Fukushima

24 analysis. And so I think we're talking about apples

25 and oranges. Okay.
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1 MEMBER CORRADINI: Okay. All right. The

2 only reason I bring it up is that at least in all the

3 analysis I've seen by the labs pump seal failure and

4 leakage into the dry well is pretty much guaranteed as

5 you cook everything.

6 And the model in MELCOR cooks even longer

7 than MAP cooks which means I should have leakage of

8 water up to the nozzles which means I've got 12 to 18

9 inches of water always there.

10 I'm sorry that I'm still back in physics

11 land. But I can't help myself.

12 So the last one is number five and maybe

13 six together. The rail door I'm not going to touch.

14 But five and six together. When I read this, I could

15 misinterpret. And again we can delay to a meeting,

16 but at least to get on the record that there should be

17 a functional relationship with all the in-vessel

18 modeling.

19 That is this parameter can be over here

20 and this parameter can be over here makes me worry.

21 Rather functionally they should be tied so that even

22 though I'm uncertain they should be uncertain in a

23 functional direction. Was that considered by the

24 subject matter experts?

25 DR. GHOSH: Yes, it was. In fact, in our
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1 peer review committee when we had interim reviews,

2 they asked us to think very carefully about what

3 correlations there should be. And we did correlate

4 some of the MELCOR parameters which we documented in

5 there.

6 MEMBER REMPE: But I never saw in the

7 documentation anything that talks about the

8 composition of the MEL which would have really

9 affected several of the parameters that I saw. For

10 example, if you've done a heat transfer analysis, the

11 size of the breach in the dry well liner whether it's

12 metallic or ceramic.

13 And so I guess that's why I keep pushing

14 to let's see some more detailed documentation of what

15 the thought processes were for the experts and did

16 they really -- Again, every expert is going to have a

17 different opinion. But there is a concern about

18 correlated variables still.

19 DR. GHOSH: Okay. Thanks.

20 So we can go to the next slide. And this

21 is an example of the regression results. As I said we

22 used four techniques. We had started with just the

23 rank regression. But that doesn't capture interactions

24 among the variables.

25 And we got better results using the
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1 quadratic, the recursive partitioning which is my

2 personal favorite and the MARS. And you can see that

3 in the more advanced methods the columns two through

4 four that TI column shows you the magnitude of the

5 interaction effects between that variable and others.

6 And you can see they are fairly high. I

7 mean the SRV has an interaction effect of 0.7 which is

8 pretty high. And that makes sense because that coming

9 together, for example, with the SRV open area fraction

10 largely determines how the accident progression goes

11 just as an example.

12 We can have the next slide, Slide 16.

13 MEMBER CORRADINI: I'm sorry. In theory I

14 read this and I know this purposefully. So the TI is

15 the interaction primer. But the ranking with the S I

16 is really kind of absolute importance. Am I right?

17 DR. GHOSH: Yes, the SI and theoretically

18 how much of the variance is explained by that variable

19 alone.

20 MEMBER CORRADINI: Okay. Thank you.

21 DR. GHOSH: Then for the MACCS results,

22 this is the list of what are the most important

23 parameters that affects the variation in the

24 individual latent cancer fatality risk. And here you

25 see there's a mix of MACCS and MELCOR variables.
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1 The first one that comes up as most

2 important across all of the methods is the dry

3 deposition velocity. At Peach Bottom I think it rains

4 less than 10 percent of the time. I can't remember

5 the exact percentage. So the main wave that you're

6 getting contaminants from the radioactive plume to the

7 ground is through this constant, slow dry deposition

8 that occurs.

9 And then over time it's mainly the ground

10 shine that's getting people in the long phase. And I

11 guess a little bit further from suspension. So it

12 makes sense that this dry deposition velocity is so

13 important.

14 Then you see a group of MELCOR parameters

15 that largely determine the source term magnitude. So

16 that also makes sense.

17 And then the last two parameters are the

18 residual cancer risk factor and the residual dose and

19 dose-rate effectiveness factor. What those are is

20 that in the MACCS right now I think we're limited to

21 about eight organ-specific cancer risk factors that we

22 can define. But there are more than eight organs that

23 we actually would want to model.

24 But we had basically was health physics

25 expert help to define a last organ, a residual organ,
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1 that kind of represented a bunch of different soft

2 tissue. We used the pancreas as a representative kind

3 of soft tissue. And all of the uncertainties in those

4 various organs was basically mapped on to this

5 residual organ.

6 It makes sense that the uncertainty in

7 that residual cancer risk factor and the dose and

8 dose-rate effectiveness factors show up as important.

9 The only other thing I'll note here is

10 that because we assigned uncertainties to those

11 counteract to some extent the dampening effect that

12 you get between the source term and the latent cancer

13 fatality risk. We're sampling what the actual -- how

14 harmful given millirem can actually be. So that has

15 a somewhat counter acting effect.

16 MEMBER RYAN: Did you pick the pancreas

17 for a particular reason?

18 DR. GHOSH: I think that was meant to --

19 I would have to go back to our documentation.

20 MEMBER RYAN: The reason I ask is that

21 there's a biological rule about radiation sensitivity

22 and the more specific in function the more

23 radiosensitive an organ is. It's the Law of Beergonie

24 and Tribondeau. And the pancreas is one thing that is

25 sensitive. It's very radiosensitive.
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1 So I was wondering why that one and not

2 some other.

3 DR. GHOSH: I'm sorry. Maybe I don't

4 explain very well. We have a report that the way the

5 factors and the mapping was done. It's very stylized

6 for SOARCA. We had Oak Ridge help us with mapping

7 that because we were limited to the eight organs. We

8 used the pancreas, but I don't think it's the case

9 that we used the distribution and the sensitivity.

10 MEMBER RYAN: But using the pancreas to

11 represent a group of kind of other organs.

12 DR. GHOSH: Right.

13 MEMBER RYAN: You picked the most

14 radiosensitive one to use.

15 DR. GHOSH: I think it's more that. But

16 we changed the input for that. So I think that it's

17 more that we mapped all of the soft tissue organs onto

18 the input variable.

19 MEMBER RYAN: It's really not kind of

20 represent the pancreas or?

21 DR. GHOSH: Right. And I need to get back.

22 It's been a while since we did that. So I need to

23 double check what we did. And I can get back to you on

24 the specifics.

25 MEMBER RYAN: Okay.
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1 DR. GHOSH: But it was meant to be this

2 catchall to map a bunch of soft tissue onto.

3 MEMBER RYAN: And so it's better to just

4 have a name than just call it other.

5 DR. GHOSH: Yes.

6 MEMBER RYAN: It's in the codes. That's

7 okay.

8 MEMBER BLEY: Tina, does this last one try

9 to cover the differences between healthy young middle

10 aged people and children and frail folks and that sort

11 of thing?

12 DR. GHOSH: Yes. Actually, the dose rate

13 effectiveness has to do with how big the doses are for

14 over a given period of time.

15 MEMBER BLEY: Is there anything that tries

16 to account for the fragility factor or whatever we

17 would call it?

18 DR. GHOSH: So all of these numbers and

19 the distributions were based on Federal Guidance

20 Report 13 which I think the EPA puts out. And we had

21 one of the authors of that report help us map

22 everything on for SOARCA. The way they came up with

23 the factors was to take a -- This is my understanding

24 -- static snapshot of the entire U.S. population that

25 includes everybody. So it includes the children, more
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1 vulnerable populations perhaps such as the elderly and

2 so on. So these factors are supposed to have all of

3 that included.

4 And I don't know if you saw that part of

5 the report. You'll see the uncertainty distributions

6 are actually pretty wide for those factors. So it

7 should be in there in the distributions.

8 MEMBER BLEY: Okay. I'm sure it is.

9 DR. GHOSH: If you go to the next slide,

10 again these are most influential parameters for the

11 prompt fatality risk. And this was really a model

12 verification exercise. All of these make sense.

13 The deposition parameter is more important

14 for being able to get a prompt fatality because that's

15 the only way you can very quickly get large

16 concentrations of radionuclides down to a particular

17 individual.

18 There was a handful of parameters, MELCOR

19 parameters, that describe both the source term

20 magnitude. And here battery duration shows up which

21 also makes sense. Because battery duration is

22 directly to the timing of the release. So when you

23 have the shortest battery durations you get the

24 earliest release which also enables you to possibly

25 get a prompt fatality.
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1 The early health effects threshold and

2 beta shape factor for the red bone marrow also makes

3 sense because that's the most vulnerable organ or

4 tissue -- I don't know what to call it -- in terms of

5 deterministic effects if that make sense.

6 And then linear crosswind, dispersion

7 coefficient, that basically describes how wide your

8 plume can get as you're traveling away from the site.

9 And the tighter plume you have the larger

10 concentrations you can get to an individual. So that

11 also makes sense that that shows up as important.

12 If we go to the next slide, Slide 18, then

13 we did this sensitivity study to look at the relative

14 contribution of the weather uncertainty versus the

15 epistemic uncertainty. Questions have come up and in

16 fact we were just talking about it earlier this

17 morning.

18 The first thing we did because this

19 question also comes up is that we used 1,000 weather

20 trials from actual weather data. And the question is

21 what if you used all 8,760 weather starting point.

22 Would you get the same answer?

23 And so we did that. And it turns out that

24 the difference is very, very small. The next slide

25 shows them. They're on the order of one to two
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1 percent for the LNT dose response model.

2 And then what I think was the more

3 interesting one, we looked at comparing the effect of

4 the weather uncertainty to the epistemic uncertainty.

5 And that will be in a couple of slides.

6 So if we go to Slide 19, that just shows

7 the differences that we computed from using all the

8 weather trials. Again very minuscule for the LNT dose

9 response model.

10 And then Slide 20, we basically picked

11 three realizations in order to look at what would be

12 the relative contribution of the weather uncertainty

13 and epistemic uncertainty. We tried to pick something

14 like a high, medium and low.

15 So realization 62 which is actually in the

16 middle is kind of a representative high outcome. 170

17 is somewhere in the middle. And the first one is the

18 low.

19 And if we go to the next slide, it's

20 interesting. We found that the weather uncertainty

21 typically is on about the order of an order of

22 magnitude for a given source term and MACCS run. But

23 the epistemic uncertainty is quite a bit wider. So we

24 conclude that. This is just an example for the 10

25 mile circular area.
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1 So we tentatively conclude that the

2 effects of the epistemic uncertainty do seem to be

3 larger than the effects of the weather uncertainty for

4 a given result.

5 MEMBER STETKAR: We don't have time for

6 that and we'll revisit it in the next meeting. But

7 there was something confusing about those comparisons

8 because the realizations that you characterized as

9 what you thought were going to be the sort of middle

10 and kind of higher and lower seem to shift in relative

11 importance when I did the weather uncertainty.

12 But just look at that. Maybe I was

13 misunderstanding those curves and we don't have enough

14 time to do that right now. But there was one area

15 where I thought that we explicitly capturing the

16 weather uncertainty and the overall results might

17 provide a better picture of what's actually happening.

18 DR. GHOSH: Yes. And my apologies. I

19 think part of the confusion stems from the fact that

20 we put the high result in the middle. And we are

21 fixing that in the report so that it follows

22 naturally.

23 For example, the blue curve is listed in

24 the middle in the legion. But that in fact is the

25 high source term. The red is the medium source term
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1 and the green is the low source term.

2 We realized that after the fact that it's

3 confusing to present it that way. And we're fixing it

4 in the report. So the legion will have and the table

5 will have 62 and 170 flipped so that it goes in a

6 natural order from low to high rather than having the

7 high in the middle.

8 MEMBER STETKAR: Okay. Go on. I wasn't

9 sure what the effect of the MACCS epistemic

10 uncertainties would be on it. When you picked the

11 single realization with the single MACCS sample I

12 didn't know. Okay. I had a high source term, but how

13 did I end up in the MACCS distribution?

14 DR. GHOSH: Okay.

15 MEMBER STETKAR: We'll have to dig into

16 this later.

17 MEMBER SHACK: Those are problems with the

18 way you've done the single realization analyses that

19 there's really only one MACCS sample associated with

20 that.

21 MEMBER STETKAR: But even that's okay

22 because here we're just theoretically sampling the

23 weather I think.

24 MEMBER SHACK: Yes, but if you're trying

25 to make an argument.
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1 MEMBER STETKAR: No, no.

2 DR. GHOSH: I understand. Yes. Actually,

3 I guess we would have the answer to that because we

4 could look at the means from those three curves

5 against the distribution of the consequence results.

6 And I don't -- 

7 I think you're right. We did not talk

8 about that in the report. So thank you for that

9 comment. I'll put something in the documentation.

10 All right. So then we --

11 MEMBER SHACK: You could also identify

12 what Cap 11 is which is a group that shows up in here

13 and it's not defined anywhere.

14 DR. GHOSH: It's not defined in -- Oh, my

15 apologies again. Cap 11 was a typo.

16 (Laughter.)

17 My apologies. We found that after we gave

18 you the report. We're fixing that as well.

19 MEMBER SHACK: I guess I don't have to

20 worry about Cap 11 anymore.

21 DR. GHOSH: No, no. Sorry about that.

22 Now I wanted to talk about one of the

23 sensitivity analyses we did because of a

24 recommendation from this Committee. And this was

25 looking at -- we did this separate from the
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1 uncertainty looking at if we had lower head

2 penetration failures, what the effect might be

3 compared to --

4 MEMBER REMPE: Before you go on.

5 DR. GHOSH: Yes.

6 MEMBER REMPE: The recommendation from

7 ACRS was talking about the drain line, not the

8 instrument tubes or the control guide tubes. And the

9 reason why the ACRS did that was because the drain

10 line doesn't have any in-core structures. It's about

11 five centimeters in ID without any investment, no in12 core probe. So it's an open flow area.

13 Also it's SA105-106 steel which has a

14 lower ultimate strength. So it's more likely to fail.

15 And that's the conclusion from the prior document that

16 we referenced in the letter.

17 DR. GHOSH: Right.

18 MEMBER REMPE: And we are aware the TMI

19 that the melt did refreeze. If you look at the

20 pictures from what melt got into the instrument tubes

21 at TMI which doesn't have a drain line it was in the

22 region between the traveling in-core probe and the

23 interior diameter of the penetration.

24 So I really am puzzled why. I mean that

25 was stated in the recommendation.
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1 DR. GHOSH: So let me answer that. Yes,

2 absolutely. And we tried to talk about that in the

3 report. So let me tell you the story as much as I

4 know it.

5 We had to use the existing models that we

6 had in MELCOR. So what we had were models for

7 penetration failures. We didn't have a separate model

8 for the drain line. 

9 However, if we go to the next slide, what

10 we tried to do is we did about 15 MELCOR ones and we

11 failed different numbers of instrument tubes. And we

12 also looked at the effective area of that drain line

13 because we recognized that that was the primary

14 concern.

15 So I think the sensitivity we did we did

16 it with what we had available to do in MELCOR. And we

17 tried to approximate what we might have seen or could

18 have done had we had a model for the drain line

19 looking at the affected area of the tubes that we

20 failed.

21 MEMBER REMPE: But did you use stainless

22 steel instrument tubes is what is typically found in

23 a BWR instead of a carbon steel tube. That's what the

24 drain line is. Or you just varied the area or what

25 did you --
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1 DR. GHOSH: I might ask Kyle Ross to pipe

2 in. We use what we had in the Peach Bottom model.

3 Kyle, if you're on the line, can you

4 answer? Did you hear that question?

5 MEMBER STETKAR: They varied the area.

6 MEMBER REMPE: Just the area, no

7 materials.

8 MEMBER STETKAR: I didn't read that they

9 varied the materials.

10 DR. GHOSH: Right. So it would be

11 whatever the Peach Bottom tubes are.

12 Kyle, are you on the line?

13 (No verbal response.)

14 MEMBER REMPE: For this presentation,

15 we're going to have a subcommittee meeting where we

16 can talk about it.

17 DR. GHOSH: Right.

18 MEMBER REMPE: But what I read in the

19 report was that we got that instrument tubes failed,

20 but it replugged at TMI. But there was no discussion

21 about in-vessel structures.

22 But it's much easier to go out through a

23 drain line. That's why again the write-up is I think

24 maybe something that should be a little possible.

25 DR. GHOSH: The reason we pointed out that
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1 it replugged in TMI is that in the model we have

2 available in MELCOR it does not model replugging.

3 So the results we have is that the stuff

4 just flowed out and we don't have a way to model that

5 replugging. That's why we pointed out that this is

6 something that we don't have right now.

7 MEMBER REMPE: I think it should be a

8 little more explicit about the reason it replugged the

9 TMI was that there were little driplets in a small

10 annular area.

11 DR. GHOSH: Okay. So we varied -- we

12 looked at failing anywhere between two to 38

13 instrument tubes which are about 1.5 inch diameter.

14 And on average 13.5 tubes failed. As I said, we did

15 50 MELCOR calculations. Not all of them ran to

16 completion. But we had a number of a tens of

17 realizations that did.

18 And we also sampled the heart transfer

19 coefficient between the penetrations and the core

20 debris and the failure temperature at which the

21 penetration would fail.

22 And we think that the smaller areas in the

23 sampled range are representative of what you would get

24 if you had that drain line. You said it was five

25 centimeters.
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1 MEMBER REMPE: Five as opposed to three

2 for the ID. But maybe 3.0 something, I haven't

3 forgotten. But there is a very large area that's got

4 traveling in-core probe. Fission chambers,

5 thermocouples inside there, too. So there's not much

6 of a --

7 DR. GHOSH: Right. So we think the

8 smaller areas in that range could be equivalent to

9 that drain line.

10 And we go to the next slide, Slide 25. We

11 saw that the penetration failures generally occurred

12 about three hours before the gross lower head failure

13 in our normal SOARCA calculations. And they were

14 relatively insensitive to variations in the other

15 sampled parameters, the heat transfer coefficient or

16 the failure temperature.

17 And usually relocation of the core debris

18 to the reactor cavity through the penetrations began

19 within about six minutes of the first penetration

20 failure. And the penetrations didn't ablate

21 significantly.

22 If we go to the next slide 26. The

23 potential influence on the relative cesium release is

24 potentially large. We saw fractional releases in the

25 range of 0.6 percent to 0.7 percent with a mean of
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1 four percent. 

2 And this is the note I think we were just

3 discussing. We know that there was plugging that was

4 observed in TMI. But that phenomena is not modeled

5 right now in MELCOR. So that's just a note for the

6 reader so that they can interpret the results

7 accordingly.

8 Then the other sensitivity analysis, we

9 did a bunch of sensitivity analyses. But the other

10 one I was going to talk about today is with respect to

11 habitability criterion.

12 We did not include varying the

13 habitability criterion as part of the integrated

14 uncertainty analysis because that's really a state

15 decision. And we know what the Pennsylvania state

16 guideline is. That's what we used.

17 But just to see what the potential effects

18 would be, we varied it between 0.l rem per year --

19 that's 100 millirem per year -- to 2 rem per year.

20 And the habitability criterion is actually 500

21 millirem per year which is in between. And we used a

22 number of other criterion.

23 CHAIR ARMIJO: That's Pennsylvania, right?

24 The 500?

25 DR. GHOSH: That's right.
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1 CHAIR ARMIJO: What's the EPA?

2 DR. GHOSH: The EPA is 2 rem in the first

3 year followed by 500 rem the following four year.

4 MEMBER CORRADINI: It's essentially the

5 same.

6 DR. GHOSH: Except that first year.

7 CHAIR ARMIJO: Yes, the first year is

8 different.

9 MEMBER CORRADINI: But I would think in

10 the first that's -- Given you had a release I would

11 think the first year is immaterial.

12 DR. GHOSH: No, because that's -- I don't

13 think it is because that's when you allow people to

14 come back. So you allow people to come back a lot

15 sooner if you allow them to get 2 rem per year. So

16 there is a difference.

17 MEMBER CORRADINI: So you see the

18 difference.

19 DR. GHOSH: You see the difference.

20 MEMBER CORRADINI: I meant the stair

21 stepping. I understand.

22 DR. GHOSH: Right. And a side note, the 2

23 rem per year case we did is probably close to the EPA

24 tag even though that second year is limited to 500

25 millirem per year because the doses drop off so
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1 rapidly after that first year.

2 CHAIR ARMIJO: Would you happen to know

3 what the gap at Fukushima for their return criterion?

4 I heard it was much more conservative.

5 DR. GHOSH: I don't know the latest answer

6 to that.

7 CHAIR ARMIJO: I don't know if anybody

8 else does.

9 MEMBER CORRADINI: What was the question?

10 CHAIR ARMIJO: The Japanese criteria for

11 return. I heard it was much more conservative, but I

12 don't know the number.

13 MEMBER SCHULTZ: It is much more

14 conservative. But I don't believe it's established

15 yet.

16 MEMBER RYAN: I don't think it's a number

17 yet.

18 MEMBER SCHULTZ: There were public

19 statements made by officials. And they're trying to

20 determine what value would be.

21 MEMBER RYAN: I'll let you know in a month

22 when I come back.

23 CHAIR ARMIJO: Okay. We're going to send

24 Mike. Ask that question, Mike.

25 MEMBER RYAN: It's on my list.
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1 DR. GHOSH: So the results are not

2 surprising. The only thing I'll point out is because

3 the 10 mile radius we evacuate there's actually a

4 larger effect of the habitability criterion because

5 everybody leaves and then comes back.

6 Once you get to the 20 mile and up radius,

7 there is some dose that's coming from the plume

8 passage overhead. So you see a smaller effect. But

9 you still see some effect.

10 And the results aren't surprising. So I

11 think I'm not going to cover them here in the interest

12 of time. We can skip that slide.

13 Slide 30 shows an example for one of the

14 alternate dose response models we used. This is for

15 the background, what we call the U.S. background,

16 which is actually the use of threshold of the combined

17 average background plus medical dose. That's the 620

18 millirem per year in the U.S.

19 And here you see for the 10 mile a much,

20 much larger difference. Don't allow people to come

21 back until they're below the dose threshold. I mean

22 you're not accruing much dose at all. And certainly

23 in absolute terms those doses are quite a bit smaller.

24 MEMBER CORRADINI: I know we're running at

25 the end. So you want to complete it. I guess between
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1 Slide 28 and Slide 30.

2 DR. GHOSH: Thirty.

3 MEMBER CORRADINI: Thirty.

4 DR. GHOSH: Yes.

5 MEMBER CORRADINI: Maybe I'm missing it.

6 Explain the difference I guess.

7 DR. GHOSH: They are two different dose

8 response times.

9 MEMBER CORRADINI: I know that, but I'm

10 not catching it though. So could you say it again

11 slower? I'm sorry.

12 DR. GHOSH: Sure. Okay. Once we use the

13 dose threshold models, you use this average U.S.

14 background dose as a threshold as well as what we

15 called the Health Physics Society which I'm not

16 showing here. This is just an example.

17 So here we don't start accruing latent

18 cancer fatality risk until you get beyond 620 millirem

19 per year a dose rate.

20 MEMBER STETKAR: And by definition anybody

21 who comes back doesn't accrue any latent cancer

22 fatalities.

23 DR. GHOSH: Right. Exactly. So you can

24 see the 10 mile risk is minuscule because the base

25 line 500 millirem per year is already below that
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1 threshold. And the 0.1 rem, 100 millirem, per year is

2 even smaller. But that doesn't make much difference.

3 What that dose is the dose to the 0.5 percent of the

4 population that doesn't evacuate. That's the only

5 thing that you're getting in the 10 mile radius.

6 MEMBER CORRADINI: So the percentages are?

7 DR. GHOSH: The percentages are the

8 difference between the base case risk and if you

9 change the habitability criterion to those numbers.

10 MEMBER RYAN: How did you get 620 again?

11 DR. GHOSH: It's the average combined

12 background plus medical dose.

13 MEMBER RYAN: Medical dose go all over the

14 map.

15 MEMBER CORRADINI: But that's the average

16 though.

17 DR. GHOSH: It's just the average.

18 MEMBER RYAN: What kind of average?

19 DR. GHOSH: Across the U.S. population.

20 It's documented in our SOARCA project.

21 MEMBER RYAN: Okay. That's not an easy

22 number to say this is the right number. Some

23 procedures have very high doses like tens of rem to

24 large portions of the body like cardiac

25 catheterization and all that sort of stuff, brain
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1 scans. And there are lots of other diagnostic things.

2 I'm just trying to figure out how you decided who got

3 what amount, how you got a "average." I don't know

4 what an average is in the population.

5 CHAIR ARMIJO: What it even means, yes.

6 DR. GHOSH: I assume we have a reference

7 for that. But I guess for our purposes we use the 620

8 millirem per year. And it was meant to represent

9 something like an average but of a very highly

10 uncertain number across the population.

11 MEMBER RYAN: Well, it's plus or minus

12 half a gazillion. You know it's big number.

13 DR. GHOSH: Sure.

14 MEMBER STETKAR: In truth it varies by the

15 population because if you're in modern, urban, fairly

16 wealthy setting you're going to get a lot more dose

17 than if you're out in a rural area where you pretty

18 much just die.

19 DR. GHOSH: Oh boy. I think we can

20 actually skip ahead to Slide 32. I just wanted to

21 point out some of the other content in the report that

22 we don't have a chance to talk about today. We did to

23 a separate sensitivity analysis for the timing of the

24 operator actions that are accredited, manual

25 depressurization and station blackout scenario.
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1 We didn't feel we could include that in

2 the integrated uncertainty analysis. But we wanted to

3 see what the potential effect would be of having

4 different timing of that action. So we reported that.

5 We looked at hydrogen generation

6 insights. Up front we have a Fukushima comparison

7 which is largely qualitative, although we have some

8 graphs in there. And then we did some --

9 MEMBER CORRADINI: This is in the

10 uncertainty.

11 DR. GHOSH: In the uncertainty analysis,

12 right.

13 MEMBER CORRADINI: I'm sorry to go back to

14 this. So it references the other report which has the

15 relatively -- I guess it's Sandia, Idaho and Oak Ridge

16 together.

17 DR. GHOSH: Right.

18 MEMBER CORRADINI: My recommendation is

19 you also consider this other one that I have mentioned

20 that was Sandia and Oak Ridge were commissioned to do

21 on ex-vessel variability.

22 DR. GHOSH: Yes. Fukushima is one of

23 those things. I think we're just going to keep

24 getting more and more knowledge as we learn more.

25 MEMBER CORRADINI: Okay. The only reason
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1 I'm emphasizing that is it's the same tools you guys

2 use. That's why.

3 DR. GHOSH: Yes.

4 MEMBER CORRADINI: And although as Ed

5 pointed out -- I don't know if Ed is still here --

6 MR. FULLER: I'm here.

7 MEMBER CORRADINI: Ed pointed out the

8 differences in the going into assumptions. I do think

9 that since you're using the same tool set it's a

10 relevant reference to have as part of the report.

11 That's all.

12 DR. GHOSH: Okay. Then we did stability

13 analyses for results and the statistical convergence.

14 We talked about some of that. We tried to document at

15 least what we did as best we could for posterity.

16 We have an appendix on the probabilistic

17 analysis methodology. And we have a discussion of the

18 MELCOR version changes since the SOARCA project was

19 complete. We did some updates in between to get to

20 kind of base line for the uncertainty analysis and

21 what their effects were.

22 And then we have an appendix where we go

23 through the peer review and ACRS comments from your

24 letter back in May and then kind of our resolution to

25 those comments. That's it for me and I'll turn it
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1 back over to Jon.

2 MR. BARR: All right. Just to quickly

3 wrap up for questions. Plans for the future, this is

4 to address comments that we get from the offices that

5 are reviewing this right now. That will happen the

6 rest of this month.

7 In September there will probably be a

8 series of presentations, some at the PSA conference on

9 this uncertainty analysis and different parts of it,

10 MELCOR part of it and MACCS, other areas.

11 Also I believe there will be a

12 presentation on this to the CSARP meeting which will

13 also be late September.

14 Once all the comments are addressed, the

15 plan would be to get this ready for publication by

16 some point this upcoming fall. I assume Tina will be

17 giving a research seminar to this offering to the

18 agency to share some of the insights learned from this

19 with the NRC staff.

20 And then another bullet to add on here

21 would be an additional meeting with the ACRS at a

22 point to be determined in the near future. Wrap up

23 and address any additional issues that are needed.

24 DR. GHOSH: And just to add to that we

25 won't be finalizing the report I think before we meet
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1 with you again. So I guess we're expecting hopefully

2 in mid September we can come back. The report is not

3 going to be final before that.

4 MEMBER SHACK: Now again one of the things

5 we want to focus on in that subcommittee meeting is a

6 more thorough discussion of the parametric modeling

7 and such. Will you be able to provide some of those

8 calculations, replications, a MELCOR replication with

9 multiple MACCS by that time do you think? Or would a

10 letter from us encourage you to do that or?

11 MEMBER CORRADINI: Discourage you or none

12 of the above?

13 DR. GHOSH: I mean it is something that

14 would be interesting to do. We can do it. I think we

15 will just have to see how our resources go in terms of

16 our competing demands on our time and so on.

17 MEMBER CORRADINI: The labs are Johnny-on18 the-spot. I'm sure they're listening now and already

19 starting to turn the wheels.

20 MS. SANTIAGO: It's a matter of resources.

21 This is Pat Santiago. We only have as we said

22 yesterday limited resources for a number of different

23 projects. So we were not really including or

24 expecting any additional funds. But we will look for

25 them certainly. And then we'll discuss that and find
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1 out what we're able to do.

2 MEMBER SHACK: More questions or comments?

3 (No verbal response.)

4 My goodness. We ended up on time.

5 MEMBER CORRADINI: That's because we

6 allowed some people to go first.

7 MEMBER SHACK: I thank the staff very much

8 for a bravura performance. I think they did a very

9 good job. And we'll be looking forward to the

10 subcommittee meeting.

11 CHAIR ARMIJO: Okay.

12 MEMBER SHACK: Back to you, Mr. Chairman.

13 CHAIR ARMIJO: Thank you, Bill. We'll

14 take a break now and reconvene at 10:45 a.m.

15 (Whereupon, a short recess was taken.)

16 CHAIR ARMIJO: Okay, we'll reconvene and

17 we'll turn it over to Dr. Ryan to lead us through the

18 Part 61 presentation.

19 MEMBER RYAN: Thank you, Dr. Armijo. We

20 had an excellent subcommittee meeting not too long ago

21 with the folks who are going to speak with us today.

22 (Knocking.)

23 CHAIR ARMIJO: Thank you.

24 MEMBER RYAN: We covered a lot of ground

25 in that subcommittee meeting and I think developed
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1 some really important understandings of what the staff

2 has done to develop the vision that they developed

3 today. So I'm hoping that we can get into that

4 discussion in a little bit more detail with other

5 members on kind of the background and the thinking.

6 So that was a very helpful and positive subcommittee

7 meeting.

8 With that, I'll be happy to turn it over

9 to Deborah Jackson from FSME who is going to introduce

10 our meeting today.

11 MS. JACKSON: Thank you very much. As

12 Mike said, I'm Deborah Jackson and I'm the Deputy

13 Division Director for the Division of

14 Intergovernmental Liaison and Rulemaking, FSME. And

15 we're here today to provide the full Committee an

16 update of the Part 61 since our last meeting in

17 September of 2001, and also inform you of the

18 information that's been sent to the Commission

19 scheduled for July 19th in a couple of weeks.

20 So the rulemaking began when staff

21 received direction from the Commission to engage on a

22 limited scope rulemaking to require site-specific

23 analysis for the disposal of large quantities of DU.

24 And based on Commission direction early last year, we

25 revised the regulatory basis document for the Part 61.
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1 And today, Andy will provide you an update of the

2 preliminary proposed rule for Part 61 and what's going

3 to the Commission as I stated earlier. 

4 So with that, I'll turn it over to Andy.

5 MR. CARRERA: Thank you, Debbie. Thank

6 you, Mr. Chairman, and ACRS members. My name is

7 Andrew Carrera. I'm the project manager for the Part

8 61 rulemaking. And up here I have with me Dr. David

9 Esh and Christopher Grossman who are mainly here for

10 scenery, as well as --

11 (Laughter.)

12 -- subject matter experts who will help me

13 in answering any of your questions.

14 The last time staff came before the full

15 Committee with a proposed revision to Part 61 was on

16 September 8 of 2011 at which point the staff also

17 received a comment letter from the Committee. Since

18 then, the staff received additional direction from the

19 Commission via January 2011 SRM. As a result of the

20 new direction, Commission direction to revise the

21 rule, staff again engaged the public, government

22 organizations, and DHRS, Radiation Protection and

23 Nuclear Materials Subcommittee which is headed by Dr.

24 Ryan in the revised rulemaking effort.

25 Based on earlier comments, including the
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1 Committee's 2011 letter, as well as a recent

2 interaction with the ACRS Subcommittee, the staff

3 revised a proposed rule language. And the staff is

4 here again today to brief the full Committee on the

5 revised proposed language for Part 61 rulemaking.

6 In preparation for this meeting, the staff

7 also provided the Committee with a preliminary Federal

8 Register notice for discussion purposes of today's

9 meeting which contained staff proposed rule language.

10 Please note that it is a preliminary document. It's

11 still making its way up through the NRC management

12 chain. It hasn't gotten to the Commission yet, so

13 when this is all said and done, it went through the

14 process. It may look a little bit different from what

15 you are seeing now.

16 Slide 2, please. 

17 So the purpose of the rule now is the

18 specify requirements for site-specific technical

19 analyses for the safe disposal of all low-level waste

20 streams. And to specific requirements for the

21 development of a site-specific waste acceptance

22 criteria and to specify other rule changes to

23 facilitate the implementation of the requirement and

24 better align the requirement with current health and

25 safety standards. And for the rest of the
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1 presentation, I will discuss each of these

2 requirements at a high level and then I will delve

3 into the details of the proposed rule language when we

4 get to the proposed rule parts.

5 And the proposed preliminary FRN, Federal

6 Register Notice, that the staff brought in front of

7 the Committee, also discusses these requirements at

8 great length and with regards to what they are and

9 what they do.

10 Slide 3, please.

11 So the center piece of this rulemaking

12 includes requirements for site-specific technical

13 analysis and requirement to develop a site-specific

14 waste acceptance criteria for disposal of all low15 level reactive waste streams. For site-specific

16 technical analysis requirement, the staff proposed to

17 add requirement to demonstrate protection of general

18 population within the 10,000 year compliance period

19 and to minimize the releases of radioactivity to the

20 extent reasonably achievable at any time during the

21 post-10,000 year period. This requirement comes in

22 the form of a performance assessment.

23 Staff also proposed to add a requirement

24 to demonstrate protection of inadvertent intruders

25 within the 10,000 year compliance period which
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1 includes stated dose limits, 500 millirem, and to

2 minimize exposure to any inadvertent intruder to the

3 extent reasonably achievable at any time during the

4 post-10,000 year period. And this requirement comes

5 in the form of an inadvertent intruder.

6 Next slide, please, Slide 4.

7 The staff also proposed to add

8 requirements to demonstrate how to dispose of the

9 system to limit the potential radiological impact from

10 long-lived waste during the post-10,000 performance

11 period. And this requirement comes in the form of a

12 long-term analysis, and I will refer to it from now on

13 as a performance period analysis.

14 So you have performance assessment that

15 would be within the 10,000 years compliance period and

16 then you have also intruder assessment, inadvertent

17 intruder assessment that would be within the 10,000

18 years compliance period. And then just performance

19 period analysis will look at the impacts post-10,000

20 year.

21 The staff also proposed to have a

22 requirement for updated site-specific technical

23 analysis as part of the license amendment for disposal

24 facility closure.

25 Slide 5, please.
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1 Staff proposed to add requirement for the

2 development of a waste acceptance plan which includes

3 the development of the waste acceptance criteria, the

4 establishment of waste characterization methods, and

5 development of a waste certification program in

6 proposed Section 61.58.

7 Slide 6, please.

8 In addition, staff proposed other

9 supporting changes such as a new definition and

10 concepts to support the site-specific technical

11 analysis requirements, require the use of Part 20 dose

12 methodology which is based, currently based on ICRP

13 which stands for International Commission on

14 Radiological Protection, Publication No. 26, and also

15 allow the use of up-to-date ICRP dose calculation

16 methodologies.

17 MEMBER SHACK: Those of that don't think

18 in terms of No. 26, what date version of that ICRP is

19 that?

20 MR. McKENNEY: This is Chris McKenney.

21 I'm the head of Performance Assessment Branch. That's

22 the 1977 version with the ICRP-30 of 1981.

23 MR. CARRERA: But we also allow the

24 licensee to use the updated one. It's got to be at

25 least ICRP 26, 1977.
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1 MEMBER SHACK: But you allow them to use

2 the more recent --

3 MEMBER RYAN: Oh, absolutely.

4 MR. CARRERA: The staff also proposed

5 revision to Appendix G, 10 CFR Part 20 and its

6 associated NRC forms as part of the program to support

7 the implementation of the proposed site-specific waste

8 acceptance requirement.

9 So in the next set of slides, I will talk

10 through the proposed rule changes of the site-specific

11 technical analysis, site-specific waste acceptance

12 plan, and touch a little bit on the supporting

13 changes, new definitions, concepts, etcetera. And the

14 staff is also developing the guidance document to

15 support the proposed rule language and it would be

16 available to the public if the Commission approves the

17 publication of a proposed rule later this year. The

18 draft document is currently not available to the

19 public, but it was shared with the ACRS Subcommittee

20 and discussed with the Subcommittee at great lengths

21 a few weeks ago.

22 MEMBER RYAN: Andrew, I think that's a

23 very important point for the rest of the audience and

24 the record to show is that we had some very important

25 I think detailed discussions about the technical
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1 aspects of what the language in the guidance really --

2 in more depth during the discussions we learned about.

3 I think that's ultimately going to be a very important

4 part of the rollout and implementation of anything

5 that comes from the rulemaking effort. That's really

6 where the concepts and the requirements of the

7 regulations are put into play. 

8 And as we all know, in performance

9 assessment you can ask a question you can never answer

10 or you can ask lots of questions that you can answer

11 really straight forwardly and then put together a

12 picture of the behavior of the system or whatever. So

13 I think that exchange reflects, in my view, the work

14 that the team, your team, has done to help put an

15 entire package together. So I just want to give the

16 audience a flavor of that exchange.

17 MR. CARRERA: Thank you, Dr. Ryan, for

18 your encouragement.

19 Slide 8.

20 In the proposed Section 61.41, which is

21 the performance objectives for the protection of the

22 general population from releases of radioactivity, it

23 would contain two paragraphs, paragraph A and

24 paragraph B. In paragraph A, the staff proposes to

25 add requirements to demonstrate protection of the
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1 general population within the 10,000 year compliance

2 period.

3 And please note that the red text that you

4 see on the screen are revised text that replaced or

5 add to the current CFR Part 61 regulations and they

6 are in a small font to differentiate it from the other

7 summary slide I have up there as well.

8 So in the proposed paragraph A, the staff

9 will retain the 25 millirem dose limit and the ALARA

10 practice and propose a requirement that the compliance

11 within this paragraph must be demonstrated through the

12 analyses that meet the requirement as specified in

13 Section 61.13(a) which is the performance period for

14 within the compliance 10,000 years compliance period.

15 MEMBER RYAN: So for everyone's benefit,

16 61.13(a) just really is the 10,000 year number.

17 MR. CARRERA: Yes, I apologize. I did say

18 performance period, but actually it's the compliance

19 period.

20 MR. GROSSMAN: Just to clarify, the

21 compliance period is defined in 61.13(a) as the --

22 61.13, I'm sorry, this is Chris Grossman of the staff.

23 I forgot to mention my name. 61.13 is the

24 specification of the analyses themselves. So the

25 performance objectives reference back to the analyses.
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1 So (a) is the performance assessment essentially.

2 MR. CARRERA: Thank you. Let's see how

3 performance assessment can satisfy the performance

4 objective in 61.41. 

5 Slide 9, please.

6 In the provided preliminary Federal

7 Register notice, also discussed the performance

8 assessment at great length. But in summary, what I

9 have on the screen the purpose of the performance

10 assessment, which is found in Section 61.13(a), is to

11 identify and examine the features, events, and

12 processes on the performance of the disposal system

13 and then provide an estimation of the annual dose to

14 any member of the public while taking into

15 consideration the uncertainties caused by these

16 feature events and processes.

17 Slide 10, please.

18 In proposed Section 61.13(a) that you see

19 on the screen here contains eight subparagraphs.

20 Subparagraphs (a)(1) and (a)(2) contain requirements

21 to consider the features, events, and processes as

22 well as the likelihood into the calculation of the

23 annual dose to any member of the public within the

24 10,000 year compliance period.

25 And the staff is developing guidance
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1 documents on how to successfully conduct your

2 performance assessment as required by the proposed

3 regulation.

4 Slide 11, please.

5 In proposed subparagraphs (a)(3), (a)(4),

6 and (a)(5) of 61.13, contain requirements for

7 providing adequate technical basis and justification

8 for models used in the performance assessment as well

9 as the evaluation, the pathway that needs to be

10 evaluated.

11 Slide 12, please. 

12 Continue on 61.13, subparagraphs (a)(6),

13 (a)(7), and (a)(8) contain additional requirements to

14 consider uncertainties and variabilities into the

15 calculations. as well as consider models that are

16 consistent with current available data and current

17 scientific understanding and identify and

18 differentiate between the roles performed by the

19 natural disposal site characteristic and designed

20 features in limiting the release of radioactivity to

21 the general population.

22 Slide 13, please.

23 So once the performance objectives for the

24 protection of the general population from releases of

25 radioactivity is satisfied for paragraph 61.41(a),
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1 which is for the within the 10,000 year compliance

2 period, we need to take a look at what we need to do

3 for the post-10,000 year period. In proposed

4 paragraphs 61.41(b) requires that we demonstrate

5 minimum releases of radioactivity from the disposal

6 facility to the general environment to the extent

7 reasonably achievable at any time during the

8 performance period which is the post-10,000 year

9 period. But the requirement would remain silent on

10 what method is appropriate to demonstrate and we leave

11 it up -- provide flexibility to the licensee to

12 determine what information they'll need to look at for

13 the long-term analysis.

14 CHAIR ARMIJO: What's the duration of the

15 performance period?

16 MR. CARRERA: There isn't a set duration

17 of the performance period. I will let Dave talk about

18 that.

19 MR. ESH: We receive some comments from

20 the performance period -- this is Dave Esh -- about

21 should we establish a duration for it and ultimately

22 we decided not to because the way we structured this,

23 the performance period can be done in a lot of

24 different ways. So somebody might want to do a cost25 benefit type of calculation. They may just want to
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1 extend their technical analyses from their compliance

2 period and actually calculate doses at longer times.

3 Or they may be looking at comparative analyses of

4 barriers and how the barriers are performing and

5 limiting releases, that sort of thing.

6 In addition, the source terms can be a lot

7 different from problem to problem and the engineer

8 barriers that are present, so it's hard to have a one

9 size fits all solution to the performance period

10 analyses. Instead, you really have to give people the

11 kind of the concept and the different ways they may go

12 about it, but then in each particular application, a

13 licensee and their agreement state regulator may come

14 in and they may decide for our particular problem,

15 here's how we're going to evaluate the performance

16 period. And the duration may be limited based on how

17 they do their analyses and the characteristics of

18 their site or it may be longer. That's the approach

19 we took.

20 We also structured it that the performance

21 period analyses only apply if you have a certain

22 amount of waste on a facility average basis. So we

23 didn't want to be in the situation where if you had a

24 minimal amount of long-lived waste everybody was going

25 to be forced to do these long-term analyses. Only in
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1 special circumstances are these long-term analyses

2 probably going to apply. And for the existing

3 facilities, I don't know if it would apply to any of

4 them right now. But when you move to a special waste

5 stream, very massive quantities of depleted uranium,

6 for instance, then you're probably going to be looking

7 at doing this performance period analyses.

8 MEMBER STETKAR: But in that sense and

9 Mike has tried to educate me on some of this stuff,

10 not as well as I could have been educated, but it's my

11 understanding that basically the radionuclides that

12 you're looking at out over those long periods aren't

13 all that sensitive. I mean what you're left with by

14 that time isn't necessarily all that sensitive to the

15 actual duration. Is that correct?

16 MR. ESH: Yes. It's more --

17 MEMBER STETKAR: I mean in general.

18 MR. ESH: You have probably like four or

19 five main variables that can all affect magnitude and

20 timing, but when you get into the performance period,

21 it's usually more of an issue of because of the long

22 half-lives of the material you're dealing with, you're

23 mainly looking at shifts in magnitude, not necessarily

24 shifts in when that impact may occur. 

25 So whether you had a dose of 100 millirem
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1 at Year 20,000 or Year 40,000, it probably doesn't

2 matter whether it's 20 or 40, and these are intended

3 to be dealing with the uncertainty and variability in

4 this type of problem, and look at it in a quantitative

5 way, but in a qualitative interpretation of your

6 quantitative information you produce. It's kind of an

7 order of magnitude type look at the problem and say

8 where am I? Is this something that's really risky or

9 is it inherently not very risky? That's kind of

10 question you're trying to answer.

11 MEMBER RYAN: Again, I point to the fact

12 we went into a lot of detail in the discussion of all

13 of that at the subcommittee and I think the real key

14 to success of this is not so much the rule language,

15 because that's very short, to the point. It really

16 gets into the application of the tools that David is

17 talking about to say well, how are we going to make

18 sense out of this and make a judgment? And I think if

19 the guidance is done in a complete and thorough way as

20 I feel confident it will be, that there's a good

21 chance it will be a workable situation.

22 MEMBER STETKAR: I'm just at this level

23 trying to get some perspective on those time issues

24 that we've talked about.

25 MR. ESH: In the future, when the guidance
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1 becomes publicly available and you desire to read 80

2 pages about FEPs, you'll be able to do that.

3 MEMBER RYAN: We'll invite you back.

4 MEMBER STETKAR: Eighty pages is something

5 that you do over lunch.

6 (Laughter.)

7 MR. ESH: Not a nice lunch then.

8 (Laughter.)

9 MR. McKENNEY: Just wanted also impart a

10 clarification based on the comments is that in the

11 direction by the Commission, they did request that we

12 set up a second time period, this performance period

13 to be not a priori set as a time period. So in a way

14 that also does jive with the Commission directions.

15 They didn't want a set time period.

16 MR. CARRERA: And proposed paragraph

17 61.41(b) also requires that compliance with this

18 paragraph must be demonstrated for analysis that meets

19 the requirements specified in Section 61.13(e) which

20 is the performance period analysis that we just

21 discussed and it provides a very nice segue into that

22 analysis.

23 So now let's see how the performance

24 period analysis can satisfy this performance objective

25 for the protection of general population from releases
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1 of radioactivity within the 10,000 year compliance

2 period.

3 Slide 14, please.

4 Also, they provide a preliminary FRN which

5 I will keep coming back to you with that. Also

6 discussed the analysis at great lengths, but in

7 summary I have up here the performance period analysis

8 which is found in paragraph 61.13(e) applies only to

9 doses close to site with certain long-lived waste.

10 And looked at the potential radiological impact on the

11 disposal site during the post-10,000 year.

12 What you see here is the proposed language

13 for the performance period analysis requirement.

14 There are two components to paragraph 61.13(e). One

15 is the requirement for the analysis and the other is

16 the screening values that would be found in proposed

17 Table 1 F of 16.13(3). And we note that this

18 requirement only applies to disposal sites with waste

19 that contains radionuclides with site average

20 concentration exceeding the screening values listed in

21 Table A which I will put up in a second, if

22 necessitated by site-specific condition. 

23 The screening values in Table A only tells

24 you if you need to do the analysis or not. However,

25 the complexity of the analysis really depends on the
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1 type of information that you want to get out of the

2 analysis to support your decision making for the

3 disposal of long-lived waste.

4 In addition, the clause "if necessitated

5 by site-specific condition" it is needed because it is

6 difficult to determine the threshold or the absolute

7 threshold for all sites because of site-specific

8 condition, the threshold below which the protected

9 risk would be acceptably low. And this clause affords

10 the flexibility for additional analysis if warranted

11 by site-specific condition.

12 Slide 16, please.

13 And here's the Table A of paragraph

14 61.13(e). And this is a new table developed

15 specifically for the performance period analysis and

16 the screening value that you see on the concentration

17 column are largely derived from class A limit table in

18 the current Part 61, Section 61.55. 

19 And in the radionuclide column note that

20 we proposed the use of long-lived alpha-emitting

21 nuclides instead of the currently found alpha-emitting

22 transuranic in Class A limit table to capture other

23 long-lived nuclides, for example, radium, uranium, and

24 thorium.

25 MEMBER RYAN: Just a second on the
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1 concentration concept. That's a concentration in a

2 waste as we see. I always think about site limits or

3 site activity limits as an amount. It's a fractional

4 release from the amount. How do I get from one to the

5 other? I know how I would do it, but I'm just trying

6 to get you folks to talk a little bit more about that.

7 MR. ESH: These concentrations are

8 facility average concentrations. So it's container by

9 container or barrel by barrel type of concentration.

10 And the idea was that we didn't want to have a

11 situation also where you have say one container of

12 waste that's above Class A and then you have a lot of

13 waste which is very dilute and that's going to trigger

14 somebody into doing this long-term analyses because

15 that's not the risk regime that we wanted to capture.

16 We wanted to capture when you have a lot of long-lived

17 waste that you're going to this analyses.

18 MEMBER RYAN: So you really focused on the

19 fractional release from the entire inventory are much

20 longer times than we think of.

21 MR. ESH: This concept is based on total

22 facility inventory. It's reflected in a concentration

23 because people will operate on a concentration basis.

24 MEMBER RYAN: And deliver it bucket by

25 bucket.
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1 MR. ESH: Yes, and they deliver it in

2 increments and discrete amounts, but ultimately the

3 disposal site operator, they're going to say I have a

4 facility of whatever size and if I fill it up with

5 waste at this concentration, that would trigger -- at

6 or above these concentrations, that would trigger when

7 I need to do the analyses. 

8 There are special circumstances though

9 where you may have concentrations below these, for

10 instance, where you'd still want to do that analyses

11 and we talk about those in our guidance document.

12 They're pretty technical and it would be much too much

13 information, we felt, for the regulatory requirements

14 to put them in there, but we wanted some flexibility

15 for people to do that if necessary. 

16 And that's because of some of the things

17 I talked about earlier. There's a lot of variability

18 in the types of materials you're going to dispose of,

19 the types of systems they go into, the types of

20 barriers you use. All those things contribute to

21 whether you have a problem that you should be looking

22 at the longer-term impacts or not.

23 MEMBER RYAN: Thank you.

24 MEMBER BROWN: Can I ask a clarifying

25 question for myself, please? When we talk about a
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1 facility, is this a building or this burial?

2 MR. ESH: Yes, these are near-surface

3 disposal facilities which in Part 61 almost

4 exclusively tend to be below-grade facilities.

5 MEMBER BROWN: How much below grade? Is

6 it 10 feet?

7 MR. ESH: It varies. At some facilities

8 may be as deep on the order of 40 to 50 feet, I

9 believe.

10 MEMBER BROWN: The top of the material

11 below the actual grade. That could be 40 to 50 feet

12 below the surface?

13 MR. ESH: In some cases. In other cases,

14 we have a facility where the top of the waste is

15 actually above grade, so they make a mounted disposal

16 facility where the waste is above grade.

17 MEMBER BROWN: Okay, second question is on

18 your concentration, I guess this goes to what Mike

19 asked you to say, but in my mind what this means then

20 is a facility, say I'm just below grade and I own the

21 facility and I've got five square miles and I go down

22 50, 60 feet, whatever, I bury stuff. I could fill up

23 that entire volume with, I just pick one of these,

24 under that concentration and not have to do any

25 analyses at all as long as my average concentration
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1 over that whole five square mile or five by five mile

2 -- not square mile, but 25 square mile, without doing

3 any analyses. Am I reading this correctly?

4 MR. ESH: For the most part. You know --

5 MEMBER BROWN: I understand there's

6 exceptions. But if you look at the requirements in

7 the table, that's the implication I would take away

8 relative to do a more detailed analysis that you

9 called for.

10 MR. ESH: One of the key factors, and

11 waste disposal and especially in low-level waste

12 disposal, the dominant pathways tend to be water13 dominated pathways in terms of release and then

14 potential dose exposures. So in the case of a

15 disposal facility, one of the key things you're

16 looking at is the dilution factor of how much is

17 released from the waste, it might be solubility limit,

18 it might not be. It might have waste forms that have

19 different dissolution and degradation mechanisms. But

20 how much waste comes out and usually we look at things

21 in the kind of a layer cake model in two dimensions.

22 So 1D transport vertically through the subsurface to

23 an aquifer and then horizontal transport through an

24 aquifer to a receptor location where you might have a

25 pumping water well, hypothetical water well, that sort
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1 of thing. 

2 So the dilution factor is really the ratio

3 of the flux rate coming from the facility to the

4 aquifer and then you have a horizontal flow through

5 the aquifer. So you have a volume of water that comes

6 in the side in a unit volume of aquifer and that flux

7 from the top is being diluted in it. So as you change

8 the aspect ratio of your facility and say you made a

9 really massive facility, if you put a massive facility

10 over a limited size aquifer, then you're going to

11 start running into issues with your dilution factor.

12 But for normal ranges of dilution factors, as long as

13 you meet these concentrations on a facility average

14 basis, you're not going to have any trouble.

15 MEMBER RYAN: One thing I think is helpful

16 to add to that, Charlie, is that -- correct me if you

17 don't agree, David, but it's not only the site and how

18 it behaves, but during the operational period, there

19 is quite a lot of on-site monitoring in the aquifer

20 and off-site monitoring and development of a very

21 detailed understanding of a geohydrologic model from

22 the surface down to the site on into an aquifer or a

23 release point whatever it might be, so that after a

24 facility is licensed, it then goes through a period of

25 operations in decades. And during that period of
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1 decades, there's a lot of information gathering that

2 certainly does go on and I think could go on to

3 address whatever the requirements are in the guidance

4 memo that say you need to understand how this is going

5 to work over time. It's that body of information that

6 then helps you to say well, we feel confident we now

7 understand this site in some detail and this is how we

8 feel it's going to behave over time and what the

9 performance is going to be over time. So if you don't

10 agree with that, let me know. I think that's

11 generally how it all fits together.

12 MEMBER BROWN: One more question relative

13 to this, maybe one more. Waste comes in from some

14 place. It comes in a truck or a container or is it

15 just dumped in or -- I didn't say anything about

16 containment. Maybe it's there, but container -- I

17 presume there's container requirements that you

18 obviously bury the stuff in a container of some kind

19 and I mean if the container was impermeable then

20 dilution factors -- if it were impermeable --

21 MR. ESH: Indefinitely, for instance.

22 MEMBER BROWN: Indefinitely, for whatever

23 that means, then that certainly reduces the risk of

24 whatever, no matter how much you have spread around.

25 MR. ESH: It certainly does and that's why
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1 I think moving to the site-specific analysis allows

2 people to credit the things that they need to credit

3 in their analyses.

4 So in the existing regulation,

5 particularly for the intruder protection, the NRC

6 developed the tables, the waste classification tables

7 that somebody compares against to determine whether

8 they're meeting the 61.42 performance objective in

9 addition to some other requirements regarding

10 segregation and barriers.

11 But that is done on a very -- the ability

12 to consider site-specific characteristics is very

13 limited in that sort of approach. In the approach in

14 the revised rulemaking, somebody can consider the

15 site-specific characteristics such as the barriers or

16 containers that you mentioned. In current practices,

17 almost all or I believe all waste is containerized.

18 And it usually goes into some sort of engineered

19 facility. So in some cases, concrete-type vaults are

20 used below grade. In other cases, they're engineered

21 natural materials such as clay layers and things of

22 that nature. But it isn't just backing up a truck and

23 dumping material in. That is what was done 40 years

24 ago. But the practices have changed dramatically from

25 40 years ago to today.
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1 And in fact, in the past, I ran across an

2 interesting picture of -- there were men at the edge

3 of what looked like a pond with barrels floating in it

4 and they had guns. They were shooting the barrels to

5 make them sink again because they had floated from the

6 water that had filled up in the pond. That was their

7 solution to seeing these floating barrels in the pond.

8 MEMBER RYAN: We have a comment, I think.

9 MS. GALLOWAY: Yes, this is Melanie

10 Galloway from DILR. I just wanted to be clear that

11 when we're talking about no assessment, we're only

12 talking about the post-10,000 year period. Every

13 facility will have to do the performance assessment.

14 So I just wanted to make sure we weren't introducing

15 some confusion by going a little bit too quickly.

16 MEMBER RYAN: For the record, you used the

17 acronym for your organization. Would you --

18 MS. GALLOWAY: I did. It's the Division

19 of Intergovernmental Liaison and Rulemaking.

20 MEMBER RYAN: Thank you very much.

21 (Laughter.)

22 CHAIR ARMIJO: Somewhere along the lines

23 somebody has to ask the question why 10,000 years?

24 Why is it justified? Why is it necessary? And what's

25 the safety benefit? And if you require these
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1 analyses, how can you convince any reasonable person

2 that those analyses have merit? 

3 MEMBER RYAN: I want to put that on the

4 record because that -- any time you want to do it,

5 Dave, because we've gone over this during the

6 subcommittee, but we haven't done it --

7 MR. ESH: We thought long and hard about

8 that issue and did a lot of evaluation of it and it's

9 reflected in the technical basis documents for the

10 rulemaking. We looked at what's done internationally,

11 what's done domestically, what's done in other

12 programs, why it's done, the different approaches that

13 are used. People use a lot of different approaches,

14 but when we looked at what's been done at NRC, at NRC,

15 we've had a guidance document since Year 2000 that was

16 developed by the Performance Assessment Working Group.

17 They had recommended 10,000 years for a compliance

18 period for low-level waste disposal. 

19 And there's a variety of reasons why that

20 period was selected, but basically, if you choose a

21 very short period, you aren't able to distinguish good

22 facilities from bad or good practices from bad because

23 basically you can all pass a short period. It doesn't

24 take a whole lot in these waste disposal problems. So

25 what happens is there's many things that can cause
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1 delays such as an engineer barrier or absorption of

2 the radionuclides when they're transported from the

3 source term to the receptor location. But the delay

4 might just be that. It's not a reduction in risk.

5 It's just a delay in risk. That risk will be realized

6 at some point in the future. 

7 Now what's the obligation in terms of time

8 for protecting people? Well, the existing regulation,

9 specially 61.42 -- 61.41, which is the protection of

10 the general population from kind of all pathways is

11 silent on the period of performance and that's partly

12 why the Performance Assessment Working Group generated

13 their guidance document in NUREG 1573 because there

14 wasn't a number in the regulation and people did

15 things differently. So we don't have any current

16 sites that are licensed under NRC. They're all done

17 in the agreement states. And the agreement states

18 have looked at that differently and kind of very

19 diverse interpretations of the requirements. But

20 61.42 says that an intruder must be protected at any

21 time in the future right now, the existing language,

22 prior to our rulemaking. 

23 So somebody could say well, they only have

24 to do 500 years now or whatever the interpretation

25 might be. Well, that means you're interpreting any as
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1 500. I can understand that people interpret it

2 differently, but the language is what it is. But when

3 we looked at the technical aspects of the problem,

4 trying to balance that with the policy and the

5 technical, the 10,000 year number would allow us to

6 see the risks from most of the longer-lived waste in

7 that 10,000-year period. It would also allow us to

8 distinguish between the performance of facilities that

9 are inherently say riskless or limited risk because of

10 the type of material that's being disposed of and

11 where you're achieving the low risk or the low

12 estimates of doses because of things in your analyses.

13 And that's important to know because the regulator has

14 to look at the analyses, break them all down and say

15 okay, are you getting these results that say you meet

16 the requirements because you're using engineered

17 barriers and you're crediting solubility limits or --

18 what is the reason why you're achieving these

19 compliance numbers? You don't get that sort of

20 information if you don't require somebody to do the

21 analysis.

22 MEMBER RYAN: That's a different question.

23 If I may just jump in, I don't have a very big

24 inventory. So it's a system that you somehow have got

25 to look at every element in the system and see what
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1 it's contributing toward the safety that you're

2 getting. So that's a good point.

3 MR. ESH: The other main issue was we

4 looked at say shorter numbers and we said well, what's

5 been done in low-level waste to date? And two out of

6 the four facilities have been licensed using 10,000

7 years or longer. And one currently has an analysis

8 submitted to them using 10,000 years and longer. So

9 three out of the four have used analyses of 10,000 or

10 longer to evaluate the safety of their facility. So

11 if you say to me well, how can you convince a

12 reasonable person of these analyses, well, people have

13 done that apparently because they've licensed

14 facilities using analyses of 10,000 years and longer.

15 CHAIR ARMIJO: That's important to know,

16 but have these been challenged in court? Technically,

17 as an engineer, do you really believe that you can do

18 an analysis taking all the uncertainties,

19 environmental uncertainties, materials uncertainties,

20 governmental uncertainties, 10,000 years -- the United

21 States in all likelihood won't exist as it is today

22 and maybe not at all. And there's nothing wrong with

23 that, that's the way things change. But if somebody

24 wanted to say well, I challenge that analysis, it's

25 not adequate. It's not taking this into account, that
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1 into account, that into account. We believe this

2 license should be re-looked at, re-analyzed. That's

3 really what I'm worried about, that you've got

4 something that's really impossible to achieve, but you

5 do it anyway and nobody -- as long as nobody objects

6 that's -- it's just paperwork.

7 MR. ESH: I understand your concerns, but

8 the practical experience is that those are licensed

9 and operating. They're not under continual challenge

10 about the quality of the analyses. The other, I

11 think, main concern with this from my perspective as

12 say a risk uncertainty person is the message that I'm

13 getting from you is that the uncertainty is very

14 large, therefore why are you requiring this? Well, if

15 the uncertainty is very large, how are you making a

16 safety decision? How are you determining the safety

17 --

18 CHAIR ARMIJO: I understood your initial

19 thing. The reason it made a difference to me was that

20 what you're really after is how can you determine

21 which is a good waste disposal site versus a not good

22 waste disposal site because anybody can meet a 100-

23 year criteria.

24 MR. ESH: Yeah.

25 CHAIR ARMIJO: With cardboard boxes maybe,
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1 I don't know. So but then you go into this extremely

2 long period of time to do what you could do today and

3 say here, these are the criterion that constitute a

4 good waste disposal site and this is what we're going

5 to measure you against, depth of disposal, concrete

6 barriers, whatever it is that you really want in these

7 low-level waste sites, just say it up front and make

8 it deterministic instead of this far into the future

9 analysis that has so many variables that it's -- I

10 find it very hard to believe.

11 You may not be challenged in court, but if

12 it was, I don't think you could survive.

13 MR. ESH: I don't know about that because

14 I'm sure they were challenged by people that wanted to

15 challenge them, but the technical realities are is

16 that this is uncertainty associated with time frame.

17 But in my opinion it's no different than the

18 uncertainties you deal with in an active reactor

19 system, for instance. You're still dealing with tail

20 risk and our estimation of probabilities of things

21 that we haven't observed very much. So in this case,

22 we haven't observed what's going to happen many

23 thousands of years into the future from the societal

24 component. And that's why we recommend you choose

25 scenarios that are somewhat constrained, fix that part
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1 of the problem and then analyze the other technical

2 aspects of the problem. 

3 So there is uncertainty associated with

4 say estimating radionuclide travel times, but I would

5 say in many respects, those estimates are probably

6 less uncertain than things like estimating piping

7 failure in a reactor system under very extreme and to

8 date not very well observed conditions. So you're

9 dealing with a different type of uncertainty and you

10 have to manage that uncertainty, but I don't think the

11 right approach managing uncertainty is to say make the

12 requirements easier. I think if you're dealing with

13 high uncertainties, generally what you do is you

14 employ a conservative approach. That's one way to

15 manage uncertainties. 

16 In this case, low-level waste disposal is

17 not the end of the line. If you have material that's

18 not suitable for near-surface disposal, they can be

19 disposed of as transuranic waste or high-level waste

20 if necessary. There's no need besides like a balance

21 between financial costs and risk that you're trying to

22 balance these two things. There's no necessity that

23 you have to put all this material in the near surface.

24 You need to do the regulatory analysis to determine

25 when it should be in the near surface and when you
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1 maybe need to explore something else. If you set the

2 requirements too light, you're never going to make

3 that determination.

4 MEMBER RYAN: Sam, I think one important

5 factor here is that site starts to operate, sees waste

6 on Day 1 and they cut the ribbon and off they go. As

7 a facility operates and I'm sure it's true for every

8 facility that's operated, they learn more about the

9 site as they go along, whether it's the geohydrology

10 or the radiological conditions or anything else

11 related to their operation, it's a learning

12 experience. So I think that at some point you've got

13 to give credit. 

14 If a facility operates for 30, 40, or 50

15 years and they've got 50 years of geohydrologic data

16 in and around the site at some reasonable distance

17 which they all probably have, I know some of them have

18 it now, that's kind of, I think, going to give them

19 enough information to improve their understanding over

20 time. 

21 You start out uncertain, as David has

22 mentioned, but I think some of the requirements are

23 unspecific at including the knowledge and the

24 hydrological environment you're in over time.

25 MR. ESH: And the primary issue is this,
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1 if you don't have much material, your analysis will be

2 very straight forward and not complex. There's no

3 regulatory burden. If you have a lot of material that

4 can cause risk, then your analysis will be more

5 complex because you need to manage that risk. The

6 requirements are designed to allow somebody to do

7 that. So even though the compliance period is 10,000

8 years, if I designed a hypothetical facility that I

9 was only taking cesium and strontium, yeah, what's the

10 burden for running the calculation out to 10,000

11 years? All my material will be decayed in 500 years.

12 There's no regulatory burden on me for needing to

13 perform that analysis. Only if I actually have

14 material that persists and can cause risk is it going

15 to create a burden. But these aren't just

16 calculations. I'd say in the intruder area, it's more

17 of a calculation. In the performance assessment area,

18 it's more of a model, but I'll use that term very

19 loosely because you can't validate for these time

20 frames. 

21 I think it's part of your issue, but

22 what's really important is the model support. So we

23 have a lot of text that we put together on model

24 support. I think the high-level waste program was

25 doing that area very well. Eventually, they used
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1 things like field experiments, natural analogs,

2 comparison of models and models. There's a variety of

3 things they do to try to build technical confidence in

4 the results which is what you're talking about. How

5 can you develop confidence in the results?

6 Absolutely important. I agree with you

7 totally on that aspect of it, but I believe you can

8 achieve confidence in the results if you do those

9 things. For a system where you have a lot of waste

10 and it's going to cause risk, it's going to cause a

11 lot of work to be able to develop the basis to support

12 your calculations. For one, where your material

13 doesn't cause a lot of risk, you can do some very

14 simple things to develop the support for your

15 calculations and demonstrate that they meet the

16 requirements. So you know, give them what we have to

17 work with. That's the best we can do to quote unquote

18 risk inform and we think that that works and it's

19 going to afford some flexibility to our --

20 CHAIR ARMIJO: That's very helpful, David,

21 but if it is that straight forward and it is not

22 burdensome for people to have really no problem and it

23 forces the people who have long, very long-lived,

24 large quantities to do things differently, that's

25 great, but you could always start at the beginning and
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1 say if you have large quantities of let's say DU,

2 massive quantities, you are not going to do your

3 surface disposal. You're going to have to do

4 something much better than that. Why not do that

5 right up front, instead of pushing it through an

6 analysis?

7 MR. ESH: We considered that especially

8 because depleted uranium was the initiator for this

9 whole process. But then when we looked at it we said

10 hey, let's be a little smarter than this if we can

11 because it's not necessarily just say uranium that

12 wasn't reflected in the waste classification tables

13 that could cause the problem, they could be any sort

14 of waste stream that is much different than what was

15 envisioned when that original analyses was done in the

16 early 1980s. 

17 So what we're dealing with is a system

18 where we may have different waste that need to go into

19 it, but if our requirements are rigid and set at a

20 certain type of analyses and a certain point in time,

21 then how are we going to ensure the safety for those

22 things that are different? Instead, let's just

23 require the technical analyses like we, the NRC would

24 do if we did the analyses to develop a concentration

25 table. Instead, let's set the requirements for
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1 somebody else to do those analyses and then they

2 reflect the things like their site-specific

3 environmental conditions and their actual waste forms

4 and their containers and their barriers and all those

5 sorts of things, their site geohydrology. All that

6 can be reflected in their analyses and therefore maybe

7 some sites can take a lot more waste under that

8 approach and maybe would some would take less. 

9 Maybe -- if you look at the response to

10 comments in the early 1980's EIS when the NRC came up

11 with waste classification tables, I think it was Los

12 Alamos or one of the national labs wrote in and said

13 hey, even though you base the concentration values in

14 the waste classification tables on a humid site,

15 something like plutonium would be much higher in an

16 arid site because of the resuspension of it. You have

17 that sort of complexity that when you try to reduce it

18 into a table, it all gets lost. Where if you allow

19 people to do the analyses then that sort of complexity

20 can be reflected in their analyses, if they choose to.

21 They might choose to say hey, I don't want

22 to mess with this, I'm going to do a conservative

23 analyses and set my waste concentrations. I can take

24 these and if I'm a for-profit business and I can make

25 money off those concentrations, that's what I do.
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1 That's -- it affords a lot of flexibility for people

2 to balance this present-day cost versus protecting

3 future generation decision. 

4 I don't think the requirements are forcing

5 people to meet some sort of NRC requirement with that

6 respect. It allows them some flexibility in how they

7 choose and design their facilities and the material

8 they take to kind of answer that question.

9 Ultimately, we all pay for the cost of those

10 facilities.

11 MEMBER RYAN: The idea I take away from

12 this is what's ultimately going to be more important

13 is not the rule. The rule, of course, has its own

14 standing, but it's the guidance document that the

15 staff basically has said to meet these requirements in

16 this setting we need to do this kind of analysis. So

17 the old question I ask many, many times is when am I

18 done. All this is is an attempt to say if you do

19 these things and get the information and do the

20 analysis, you might get done quicker than you think.

21 CHAIR ARMIJO: The other thing that

22 bothers me about the 10,000 years is the Department of

23 Energy specifies 1,000 years for their waste and I

24 think includes depleted uranium. I'm not sure, but I

25 believe it does. And so here we have the government
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1 regulating itself to a much lower standard than we

2 regulate the private sector and that's something that

3 should be avoided. Really, there's something wrong.

4 If it's good enough for the government, why isn't it

5 good enough for private sector?

6 MR. ESH: There's a couple points about

7 that. First of all, in their incidental waste sites,

8 most of those, they're analyzing out to 10,000 years

9 and longer. So they look longer, just like this -- we

10 have this conceptual framework of two tiers and

11 looking for a certain period and then evaluating out

12 further. In the analyses that they submit to us, they

13 reflect that, that sort of conceptual behavior for the

14 most part.

15 In addition, they have institutional

16 control ability for -- they say in perpetuity, but

17 when they do their analyses, they don't analyze it

18 like they have in perpetuity, but because it's a

19 government-owned site they believe they're going to

20 have long-term ownership of it. That kind of

21 alleviates the burden of what are the long-term

22 impacts if you believe you're going to control the

23 site. 

24 The third point in that regard is when DOE

25 -- DOE originally had 10,000 years for their analyses
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1 for their different waste and they had an expert group

2 that they formed to look at that issue and that group

3 recommended 10,000 years. And then DOE somewhere in

4 the process, headquarters or whatever switching it to

5 1,000 years and they had a justification for that.

6 But that justification, in my opinion, is not very

7 strong and they went against the recommendation of

8 their experts. So we had to factor that in. We know

9 that DOE uses that for their waste disposal

10 facilities, but we don't think that you're able to see

11 this issue of the behavior of your facility and how

12 you're achieving your risk limits with that short

13 analyses and you don't even come anywhere close to

14 capturing what could be the peak risk with that cut15 off time frame. 

16 So if there's a moral obligation to only

17 analyze 1,000 years, that's an issue that the

18 Commission could make a statement on and that's what

19 it is. But we don't feel that we have any guidance on

20 that aspect of the problem, but you're looking at all

21 the other criteria, we came out where we came out.

22 CHAIR ARMIJO: Okay, thank you very much.

23 MEMBER RYAN: Another comment?

24 MS. SUTTORA: Yes, this is Linda Suttora

25 with the Department of Energy. And I would like to
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1 object to a couple of things that were said. One is

2 that we had originally considered 10,000 years. We

3 considered a lot of things in analyses in developing

4 5820, Department of Energy Order 5820.2(a) and DOE

5 order subsequent version which was 435.1(b). There

6 was a lot of papers written in the development of

7 those orders and the fact that one paper recommended

8 10,000 years would not constitute that we rejected the

9 higher protectiveness.

10 I also object to calling 1,000 years lower

11 protectiveness because, as we all know, most of the

12 shorter-lived radionuclides are gone by 500 years, so

13 we double that to be protective. We also always

14 analyze out to peak dose and we take into

15 consideration the peak dose and in fact, 10,000

16 doesn't even come close to discovering the peak dose

17 of depleted uranium that's actually out past 40,000

18 years. So by saying 10,000 years --

19 MEMBER RYAN: It's probably outliving the

20 planet.

21 MS. SUTTORA: Pardon me?

22 MEMBER RYAN: It's probably outliving the

23 planet.

24 MS. SUTTORA: Yes, so -- by saying that

25 1,000 years is less protective than 10,000 years is
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1 actually warping the analysis because 500 years is

2 pretty much all you really need to go to and that has

3 been analyzed by many countries and many states and

4 also analyzed by other organizations such as the

5 National -- I can't remember what it stands for NAPA,

6 which did a study on -- that they said just a few

7 generations was enough. 

8 So we should be very careful on what we

9 say is more protective than another analysis. It's a

10 different analysis, but since we always go peak, then

11 we do always discover what the peak dose is and we may

12 modify our disposal's activities based on where the

13 peak might be, maybe put it deeper, maybe put a more

14 substantial cover and all that.

15 CHAIR ARMIJO: I appreciate that. Thank

16 you very much. I appreciate that. Okay, that was

17 worth discussing because that's going to be an issue.

18 Go ahead, Dave. Thank you.

19 MR. ESH: The only thing that I would have

20 to add on that is that we were -- the initiator for

21 this was the depleted uranium from the Commission.

22 That's 08-147. When we looked at that, the peak dose

23 -- the dose from your depleted uranium at 1,000 years

24 is only about 1/1,100th of where it ends up. The dose

25 --
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1 MEMBER RYAN: It ends up dead.

2 MR. ESH: Around 1.6 million years, but it

3 depends --

4 CHAIR ARMIJO: That's beyond my concern.

5 MR. ESH: But at 10,000 years, you're

6 about at 1/10th of the peak dose. So if I'm sitting

7 here as a regulator and trying to order with some

8 stakeholders that I'm making regulations that are

9 going to protect their health and safety, I don't know

10 how if I only have 1/1000ths of the risk realized at

11 1,000 years that I say I'm doing that. It doesn't

12 even come close.

13 MEMBER RYAN: But David, one point that I

14 think is important for folks to understand is that

15 1,000 years or 10,000 years at some point we're all

16 here and we've got a country and we're going to

17 control this and we've got large regulations and smart

18 people to take care of. I just think it's hard to

19 project out in time who is going to be doing what

20 when. 

21 So to me, one thought is to focus on the

22 first 1,000 years for the technical, a good, solid

23 technical analysis where you've got higher probability

24 and capability to make estimations and how things are

25 going to behave, what behavior might be like and all
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1 that. A thousand and ten is where things kind of fall

2 off the truck at least from my way of thinking about

3 who's going to where, when, and what are they going to

4 be doing?

5 MR. ESH: I understand what you're saying,

6 but in some aspects I disagree with part of it in that

7 I think that uncertainty in the societal aspect is

8 much larger and probably occurs earlier. All you have

9 to do is look at say what was going on here 50 years

10 ago and 100 years ago and 200 years ago and how much

11 it's changed over time. If you ask somebody 200 years

12 ago what would we be doing today, they would have been

13 way off with what they probably estimated. So society

14 uncertainty, I think is very large which is why we say

15 this is a regulatory analysis. It's the best we can

16 do today to try to estimate what's going to happen

17 with these problems. We're to constrain the societal

18 uncertainty and we're going to allow people to

19 technically evaluate the other parts of the problem.

20 That's the way the performance assessment works.

21 Some groups internationally, they look at

22 the full uncertainty and the human aspect of the

23 problem which I think is counter productive. All is

24 a game about speculating about what one group can do

25 and what imagination they have compared to another
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1 group. It doesn't benefit anybody. But if we can

2 pick scenarios that are based on basic human

3 activities that we think people will need to continue

4 like eating and living in a house and things like

5 that, we think that's a reasonable regulatory analysis

6 to ask somebody to perform.

7 So in that respect we think the

8 uncertainties in 1,000 years are not much different

9 than in 10,000 years. When you get to 100,000 or

10 1,000,000 years and you're talking about broad,

11 landform evolution and those sorts of things now

12 you're in a different ball game, but 1,000 to 10,000,

13 not measurable differences in uncertainties. If

14 anybody thinks there are measurable differences and

15 uncertainties in natural systems or whatever, I'd like

16 to hear about that.

17 CHAIR ARMIJO: But David, given that

18 point, why don't you just say hey, there's are not

19 going to be much difference after 1,000 years, 10,000

20 years. Why don't you just truncate it at 1,000 and

21 you tell the public hey, we take care of future

22 generations up to 1,000 years and from then on you

23 guys have got to take care of yourselves. We can

24 reasonably presume that future generations have some

25 competence to take care of themselves, so it's just an
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1 analysis. If it becomes burdensome and expensive and

2 it limits a siting or licensing of facilities, that's

3 counter productive.

4 MR. ESH: I think you've misinterpreted

5 something I said or I've misrepresented it. There's

6 not much difference in the uncertainties associated

7 with those two time periods, but there can be extreme

8 differences in the risks associated with those two

9 time periods. So in these problems, you transport

10 material from the source out of the system. The

11 natural system or the engineered system can create

12 delays in those materials. So what you see in that

13 initial 1,000 year period may be a tiny fraction of

14 what you're going to see in the post-1,000 year

15 period.

16 CHAIR ARMIJO: But we don't have to worry

17 about it. You've chosen to worry about it, but I

18 think we don't have to. You can just do an analysis

19 and that's it.

20 MR. ESH: You can, but we don't have a lot

21 on this from Congress, but there is some material in

22 the '70s where they basically talked about this

23 subject and my interpretation of it is they believe

24 that the material should be managed for as long as

25 it's hazardous and they mentioned 250,000 years.
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1 That's all we have. 

2 If you want to say well, Congress, you got

3 this wrong --

4 CHAIR ARMIJO: Yes, I have no problem

5 saying they got it wrong.

6 MS. JACKSON: Andy is barely halfway

7 through his presentation. I was wondering if we could

8 move on and maybe -- we have another topic that's

9 going to bring a lot of discussion. 

10 Any has about 20 more slides we'd like to

11 get through.

12 MR. CARRERA: I'll wrap this up very

13 quickly so you will have additional time.

14 MS. JACKSON: So we can have some

15 additional discussion.

16 MR. CARRERA: Imagine five years with Dave

17 of meetings like this.

18 MEMBER RYAN: I appreciate the discussion.

19 It's been very helpful.

20 MS. JACKSON: It's been a very good

21 discussion.

22 MR. CARRERA: Thank you.

23 MS. JACKSON: But Andy's put a lot of work

24 and we want to make sure he gets to the slides.

25 MR. CARRERA: Thank you. Once we've
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1 demonstrated compliance with the performance

2 objectives in section 61.41, we now turn to

3 performance objectives for the protection of

4 inadvertent intruder in Section 61.42. The

5 performance objectives for protection of inadvertent

6 intruder also has a two-tier framework. It's based on

7 a two-tier framework, 10,000 year compliance period

8 component, and a post-10,000 year performance period

9 component.

10 MEMBER BROWN: Does that mean accruing 500

11 millirem over 10,000 years?

12 MR. GROSSMAN: That's an annual.

13 MEMBER BROWN: I'm sorry. I sped right

14 past the annual. I apologize for that.

15 MR. CARRERA: In proposed paragraph A of

16 Section 61.42 contains recent requirement for the

17 stated annual dose limit of 500 millirem which is what

18 staff has used to support the one staff developed,

19 Table 1 and 2 of the 10 CFR Part 61. 

20 Paragraph A also requires that the

21 compliance with this paragraph must be demonstrated

22 through the analyses that meet the requirements

23 specified in Section 61.13(b) which is the inadvertent

24 intruder analysis.

25 Let's see how an inadvertent intruder
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1 analysis can satisfy these performance objectives for

2 the 10,000 year compliance period. Going back to the

3 provided preliminary FRN, it also discusses the

4 inadvertent intruder assessment in great length, but

5 in summary the purpose of an inadvertent intruder

6 analysis which is found in paragraph 61.13(b) is to

7 examine the capability of intruder barrier and

8 estimate the potential annual dose by considering

9 uncertainties involved in the inadvertent intruder

10 scenario.

11 In the guidance document we have

12 additional discussion of the type of inadvertent

13 intruder scenarios that we can satisfactorily use to

14 demonstrate compliance with this requirement.

15 DR. BALLINGER: I have a question. 

16 MEMBER STETKAR: Ron, you have to --

17 DR. BALLINGER: Ron Ballinger. How does

18 this compare with the land occupancy requirement?

19 Isn't the land occupancy requirement that we've been

20 talking about a little while --

21 CHAIR ARMIJO: Habitability?

22 DR. BALLINGER: Yes, habitability. That's

23 500 millirem per year, right? So if this limit is 500

24 millirem per year and the land occupancy for just

25 occupancy is 500 millirem per year, how is it an
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1 intruder? Maybe I'm missing something here. There's

2 a land occupancy which we've been talking about which

3 is that dose is 500 millirem --

4 MEMBER STETKAR: State of Pennsylvania.

5 DR. BALLINGER: In the State of

6 Pennsylvania. Well, there's a land occupancy in every

7 state. That's 500 millirem per year for Pennsylvania.

8 So what we're saying is is that if we go to a waste

9 disposal site in Pennsylvania, after the closure

10 period if somebody goes there by definition they must

11 be an intruder. Where am I missing something here?

12 MR. GROSSMAN: The purpose of this is to

13 look at -- okay, so 61.41 deals with releases from the

14 facility to the general environment. This is, I

15 think, kind of an acknowledgement that because this

16 material is in the near surface, the likelihood that

17 someone may in the future intrude into the site or

18 excavate some of the waste, the likelihood of that is

19 a little higher than maybe other disposal concepts

20 such as with high-level waste. So there was an

21 acknowledgement that we need to be looking at that and

22 so performance objectives are set up to protect

23 someone who comes on to the site and inadvertently

24 intrudes into the waste. 

25 There's a distinction in the intruder
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1 concept between advertent and inadvertent. An

2 advertent intruder being someone who knows, actively

3 knows that they're digging into something, they're

4 taking those risks on themselves. This isn't designed

5 to protect them. But for someone who doesn't -- isn't

6 aware maybe through some bureaucratic error was

7 allowed to come on to the site and build a residency

8 --

9 DR. BALLINGER: What I'm saying by the

10 land occupancy rule, they are allowed to do that.

11 MEMBER BLEY: And they are here. That

12 meets the criteria.

13 DR. BALLINGER: Right.

14 MEMBER SHACK: You're giving them the same

15 dose.

16 DR. BALLINGER: That's what I mean. I

17 mean you're giving them the same dose. They're

18 consistent.

19 MEMBER SHACK: They're consistent.

20 DR. BALLINGER: But why call them an

21 intruder then?

22 MEMBER BLEY: This is for an intruder

23 somewhere later when you know you put --

24 MEMBER RYAN: You can call it someone who

25 has decided to live on a waste site if you want, but
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1 the common term that's used for somebody that's

2 theorized intruding in a waste site is an intruder.

3 DR. BALLINGER: I understand that, but

4 they're also allowed to live there as if it wasn't

5 there. He's still an inadvertent intruder.

6 MEMBER BLEY: You wouldn't call the people

7 going back to their homes in Pennsylvania intruders.

8 In this case, it's an intruder who goes into a place

9 you didn't expect him to go and you're holding them to

10 the -- you're holding the site to not expose them

11 worse than the guy you let come home after some

12 accident.

13 DR. BALLINGER: Right.

14 MEMBER RYAN: Let's move on.

15 MR. CARRERA: Slide 19, please. 

16 The proposed paragraph 61.13(b) has three

17 subparagraphs, subparagraphs (b)(1) and (b)(2) contain

18 requirement that the inadvertent intruder analysis

19 must demonstrate that the waste acceptance criteria

20 for disposed waste will be met and that adequate

21 barriers will be provided. And we'll discuss the

22 waste acceptance criteria in greater detail later in

23 the presentation.

24 Slide 20, please. 

25 Subparagraph (b)(3) contain a requirement
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1 for inadvertent intruder analysis to assume that an

2 inadvertent intruder occupies the disposal site at any

3 time during the compliance period and engages in

4 normal and other reasonably foreseeable pursuit that

5 unknowingly exposes the intruder to radiation from the

6 waste. Also, there are requirements to identify

7 adequate barriers, provide technical basis for the

8 time period that the barriers are good for and

9 consider uncertainties and variabilities in the

10 analysis. 

11 Again, the guidance document would cover

12 in great depth on how we can satisfy these

13 specifications.

14 Slide 21, please. Once the requirement in

15 paragraph A is satisfied, paragraph B of Section 61.42

16 requires us to take a look at what we need to do for

17 the post-10,000 year performance period. And

18 paragraph B requires that we demonstrate minimum

19 exposure to any inadvertent intruder to the extent

20 reasonably achievable at any time during the

21 performance period. And paragraph B also specifies

22 that compliance with this paragraph must be

23 demonstrated through the analysis that meet the

24 requirements specified in Section 61.13(e) which is

25 the performance period analysis that we discussed
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1 already.

2 Slide 22, please.

3 Finally, the staff proposed an addition to

4 the introductory text of the current Section 61.13 to

5 clarify that the required technical analysis must be

6 submitted at the next license renewal or within five

7 years of the effective date of this subpart, whichever

8 comes first. And for the NRC licensees, effective

9 date is one year after the publication of the final

10 rule. The agreement states will have an additional

11 three years to develop their compatible regulation at

12 which point they'll describe the effective date.

13 MEMBER RYAN: Andy, will you just mention

14 for everybody's benefit the number of sites now

15 currently that are either an agreement state or not an

16 agreement state.

17 MR. CARRERA: We currently have four

18 disposal facilities in four separate agreement states.

19 MEMBER RYAN: Thank you.

20 MR. CARRERA: Slide 23, please. 

21 So let us now switch gears to a different

22 type of site-specific requirement that the Commission

23 directed the staff to specify. And in January 2012

24 SRM, the Commission directed the staff to expand the

25 limited scope rulemaking to provide flexibility for
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1 disposal facilities to establish site-specific waste

2 acceptance criteria based on the results of the site's

3 performance assessment and intruder assessment.

4 And to do that, the staff has recreated

5 Section 61.58 and we titled it waste acceptance. The

6 provided preliminary FRN also discussed adequate

7 length of how the staff did that. In recreation of

8 Section 61.58, the staff proposes a new requirement

9 for the development of a waste acceptance plan which

10 includes the development of waste acceptance criteria,

11 establish waste characterization methods, and

12 development of a waste certification program.

13 Slide 24, please.

14 So proposed Section 61.58 contains eight

15 paragraphs. In paragraph A as directed by the

16 Commission, the staff proposed requirements for the

17 development of the waste acceptance criteria that is

18 based either on the result of the site-specific

19 technical analysis that we just covered required by

20 Section 61.13 or the current waste classification

21 requirements in Section 61.55.

22 Slide 25, please.

23 Paragraph A also contains requirements for

24 the waste acceptance criteria to meet the minimum

25 requirement for waste characteristics and imposes
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1 restrictions or prohibitions on waste materials or

2 containers that might affect the facility's ability to

3 meet the performance assessment. And the guidance

4 document will have additional discussions of how we

5 can satisfactorily develop a waste acceptance criteria

6 to demonstrate compliance with this requirement.

7 MEMBER RYAN: I think it's helpful for the

8 members to also realize that every site that I'm aware

9 of has a license, but they also have a site criteria

10 document of some kind that really gets into a lot of

11 detail of how you would meet that kind of requirement

12 in packaging and all the rest.

13 MR. CARRERA: Almost all, Chris, all of

14 them will have a site that's based on similar

15 criteria.

16 Slide 26, please. 

17 Paragraph B of proposed Section 61.58

18 contains requirements for waste characterization. And

19 items 1 through 7 of paragraph B represents the

20 required minimum information that is needed for the

21 characterization of the waste.

22 MEMBER RYAN: Just a quick question that

23 caught my eye. What is a generating source?

24 MR. GROSSMAN: The generating source would

25 be where that material was generated from. 
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1 MEMBER POWERS: It's what is a non2 generating source.

3 MEMBER RYAN: That's a little bit fuzzy.

4 So we'll have to think about that. It's a minor

5 point.

6 MR. McKENNEY: In parlance, that would be

7 the nuclear reactor or whatever and then because of

8 the fact that characterization does not occur until

9 the waste is about to be shipped to the disposal

10 facility, at that point is when characterization

11 occurs. So if a processor was doing the documentation

12 to complete these seven items, they would know what

13 reactor the waste came from because they are not the

14 generating source. The reactor was the generating

15 source.

16 MEMBER RYAN: So point of origin of the

17 waste is a whole lot better description than what

18 you're talking about. I just think you need to give

19 somebody a set of the buzzwords and make sure they

20 communicate what you hope to communicate. That one

21 just jumped out at me.

22 DR. BALLINGER: I actually have another

23 question. This is Ron Ballinger. This identity's

24 activities and concentrations, do they actually have

25 to be determined? Because I've received a lot of
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1 waste from utilities and it arrives with a little tag

2 that says what's in it with a letter that says this

3 came from such and such a place. And historically,

4 these are activities that we've seen and therefore,

5 we're just assuming that they're there. So you get

6 something where there's an assumption made on the

7 activities that are present and when you actually do

8 an analysis to determine what they are, you find out

9 they aren't there.

10 MEMBER RYAN: I'm going to guess that

11 that's an in-processor location? When you receive

12 these materials, are you a processor or a disposer or

13 what were you doing?

14 DR. BALLINGER: We're going to do work on

15 them. Examination.

16 MEMBER RYAN: Okay. You're not receiving

17 waste. You're receiving a licensed material that

18 you're going to either turn back or put into your

19 waste bin.

20 DR. BALLINGER: Yeah.

21 MEMBER RYAN: That's not a 61 regulated

22 activity.

23 DR. BALLINGER: All right. I'm just a

24 dummy with respect to this stuff.

25 MEMBER RYAN: I guess I'm picking on it
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1 because I don't want people to be confused about when

2 you're shipping licensed material from one licensee to

3 another is a very different circumstance whether you

4 ship it or turn it over to a waste processor.

5 DR. BALLINGER: We're acting like an

6 opiant. If something is coming -

7 (Laughter.)

8 MEMBER RYAN: Okay. Thanks.

9 MR. CARRERA: Slide 27, please. In

10 paragraph C of the proposed Section 61.58 contains

11 requirements for certification program to certify that

12 the waste would meet the waste acceptance criteria

13 prior to shipment to the disposal facility.

14 Slide 28, please.

15 CHAIR ARMIJO: Any, these are listed as

16 new requirements, but I can't believe people haven't

17 been doing this all along. It seems like it's what

18 you normally would do. Were they somewhere else?

19 MEMBER RYAN: Sam, I think it's fair to

20 say that the acceptance criteria that you would give

21 a customer has this and many dozens of pages more that

22 tells them what to do, how to do it, how to label it,

23 how to paint it, how to bolt it. All that stuff is

24 laid out, but these are now regulatory requirements

25 that will probably guide that in a little bit more
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1 detail.

2 CHAIR ARMIJO: In the past they were in

3 guidance documents and they've moved up to a

4 regulation, is that what we're saying?

5 MEMBER RYAN: Not exactly. There was a

6 requirement, but -- and I think these are just a

7 little bit more detailed and I don't mean a lot, I

8 mean a little bit more detailed in the regulation to

9 get people categories of stuff and they'll still be

10 implemented as I understand with site criteria and

11 guidance documents that are generated and so forth.

12 Is that a reasonable summary?

13 MR. CARRERA: Slide 28, please. In

14 paragraphs (d) and (e) of the proposed Section 61.58

15 contain requirements that we must demonstrate

16 compliance with this section at the next license

17 renewal or within five years of the effective date of

18 the subpart, whichever comes first. It also contains

19 a requirement -- it also indicates how the waste

20 acceptance plan would be treated for licensees and

21 license applicants.

22 Paragraphs (f), (g), and (h) of Section

23 61.58 contain requirements for an annual review of the

24 waste acceptance plan and updates of the plan would

25 require -- would have to be consistent with the
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1 Commission's policy in other sections of Part 61,

2 namely 61.20 and 61.23.

3 Just note we discussed the site-specific

4 requirements, the technical analysis and the waste

5 acceptance plan material. We talked of changes,

6 supporting changes such as new definition and concept

7 to support the implementation of the site-specific

8 technical analysis as well as changes to Appendix G to

9 10 CFR Part 20 and the waste manifest form because

10 they are inherently linked to the required site11 specific waste acceptance plan.

12 Slide 31, please.

13 So in Section 61.2 which is the definition

14 section, the staff proposes a definition of long-lived

15 waste to support the performance period analysis. And

16 the preliminary -- and provided the preliminary FRN

17 also discussed by the staff proposed to use this

18 definition at great length.

19 CHAIR ARMIJO: Has ten percent been pretty

20 much the practice in the past for the definition or is

21 that a new number?

22 MR. ESH: There isn't a real I'd say

23 practice with this. Internationally what you'll see

24 is the long-lived is usually set by a half-life and

25 quite commonly 30 years. So greater than 30 years is
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1 considered long-lived and less is considered short2 lived. That was too constraining we felt. In this

3 case, for Item 1 of this definition it works out to be

4 roughly a 3,000 year half-life, so it captures

5 something like americium-241 which we see in a lot of

6 waste streams. And it's consistent with the existing

7 tables in Part 61 where carbon-14 was considered to be

8 long-lived. Under this definition carbon-14 would

9 also be considered to be long-lived. So that's kind

10 of how we came up with it. 

11 And then it captures in-growth and decay

12 or in-growth and progeny with Items 2 and 3.

13 MR. CARRERA: Slide 32, please. Also in

14 Section 61.2, the definition section, the staff

15 proposed definitions of compliance period and

16 performance period. Also to support the site-specific

17 technical analysis and also directed by the

18 Commission.

19 Slide 33, please.

20 Also in the definition and consistent with

21 the definition section and consistent with the

22 National Defense Authorization Act for Fiscal Year

23 2013, the staff proposed the revision to the

24 definition of waste to account for the

25 reclassification of waste resulting from the
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1 production of medical isotopes that may have been

2 permanently removed from the reactor vessels or

3 subcritical assembly, for which there is no further

4 use. And these wastes will be reclassified as low5 level radioactive waste.

6 Slide 34, please.

7 In proposed Section 61.7(a)(2) which is

8 the concept section, the staff proposes to add a new

9 concept to clarify that there are waste that is Class

10 A waste by default under Section 61.55(a)(6) such as

11 depleted uranium, but may not decay to an acceptable

12 level within 100 years. And for this waste, safety is

13 provided by limiting the quantities and concentration

14 of the materials consistent with the disposal site

15 design and also can be demonstrated by compliance with

16 performance objectives.

17 Slide 35, please. 

18 In proposed Section 61.7(f)(3), the staff

19 proposes to add a new concept that clarifies the

20 purpose of post-closure observation and maintenance

21 program. And it's mainly because we received comments

22 on this.

23 Slide 36, please.

24 In proposed Section 61.7(g) the staff

25 proposes to add a new concept to indicate that
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1 licensees will need to use a dose calculation method

2 consistent with Part 20 which currently is based on

3 ICRP publication No. 26, the year 1977. And also

4 allows the use of more up-to-date later application of

5 ICRP recommendation for dose modeling purposes.

6 Slide 37, please.

7 The purpose of Revision 2, Appendix G to

8 Part 20 and the purpose of Appendix G is to address

9 various regulatory information needs for the transfer

10 of the disposal of low-level waste. These information

11 needs include the information that demonstrates

12 compliance with performance objectives in Part 61.

13 And because the staff proposed requirements for waste

14 acceptance plan, Appendix G, which is linked to the

15 waste acceptance plan would also be revised to reflect

16 a new waste acceptance criteria which characterization

17 and waste certification requirements of proposed

18 Section 61.58.

19 And Section 2 of Appendix G that you see

20 on the screen here, the staff proposed that red text

21 revision just for readability. 

22 Slide 38, please.

23 And in Section 3(a) of Appendix G, the

24 staff proposes revision to incorporate the waste

25 acceptance criteria into Appendix G.
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1 Slide 39, please.

2 In Section 3(c) of Appendix G, staff

3 includes the waste acceptance criteria.

4 Slide 40, please.

5 Because the staff proposed revision to

6 Appendix G which referenced a waste manifest form, the

7 staff also proposed to revise a portion of the

8 certification statement in NRC Form 540 and revise NRC

9 Form 541 to allow the licensees to indicate a use of

10 the waste acceptance criteria if it chooses.

11 That concludes my presentation on Part 61

12 revised proposed ruling. Thank you for staying with

13 me. I know it's a dry subject and I tried to make it

14 as sexy as I can, but that's the best I can do.

15 MEMBER SHACK: You didn't get enough

16 excitement out of this discussion?

17 CHAIR ARMIJO: We didn't attack him this

18 time, but we will.

19 MR. CARRERA: So for the path forward and

20 assuming that the Commission approves the proposed

21 rulemaking package, the staff will publish the

22 proposed rule in the Federal Register for public

23 comments in the fall or winter of 2013. That's

24 assuming the Commission will approve the publication

25 date. And the staff also plans to conduct at least
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1 one public meeting in 2014 to engage the public on

2 this proposed rule.

3 The staff will -- once we receive comments

4 on the proposed rule, staff will then consider all

5 comments, address the comments, respond to comments in

6 the final rule which is expected to come out in late

7 2014.

8 Thank you for your time.

9 MEMBER RYAN: Thank you very much, Andrew.

10 Are there any other questions from members?

11 MEMBER POWERS: A question comes up to me

12 in my mind. Do you anticipate having a public

13 meeting? What parts of this package do you expect to

14 get from those interrogators concerning from members

15 of the public and from potential or actual licensees?

16 MR. CARRERA: I think definitely DD 10,000

17 years number would attract some attention and we're

18 definitely going to get some interaction with Dr.

19 Armijo on the inadvertent intruder and scenario.

20 (Laughter.)

21 MEMBER POWERS: Do you think he's

22 particular intrusive?

23 (Laughter.)

24 I certainly do, but --

25 MR. CARRERA: It was inadvertent.
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1 MEMBER POWERS: Advertent. Quite frankly,

2 your defense in the 10,000 years was not particularly

3 glib, smooth. You made a lot of plausibility. It's

4 basically a plausibility or traditional -- following

5 tradition was the argument that was advanced in

6 defense of 10,000 years. Are you going to tone that

7 down so that you can defend it a little more facilely

8 under your interrogators?

9 MR. ESH: That's a good comment. I get a

10 little frustrated by it --

11 MEMBER POWERS: I understand . I can see

12 that. 

13 MR. ESH: We've been debating it for

14 multiple years now and --

15 MEMBER POWERS: I noticed that.

16 MR. ESH: It's something that's not really

17 quantitative and you can't make it quantitative. It's

18 a multi-faceted --

19 MEMBER POWERS: I thought your defense was

20 flawed.

21 MR. ESH: It's a multi-faceted issue with

22 a whole bunch of components and everybody has strong

23 opinions and different opinions. So what are you to

24 do about it? 

25 We considered everything and I think our
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1 best discussion on the issue is in our regulatory

2 basis documents that talks about why we recommended

3 the approach that we recommended. It goes over the

4 summary of the international experience, the domestic

5 experience, some of the technical aspects,

6 uncertainty. Shows like what happens in analyses,

7 actual analyses when you look at dose projections and

8 curves and how they can jump up tremendously,

9 especially -- and that's the main issue technically is

10 if your regulatory period is too short, you can say I

11 meet all the regulatory requirements, but you have

12 this massive risk or liability looming in the future.

13 And if you go back and look at the documentation from

14 the '70s about how Part 61 even came in to be,

15 originally the disposal facilities were having a lot

16 of trouble and some of those are now closed, are

17 surplus sites because they had so much trouble.

18 So Congress said look, we need to do

19 something about this. Let NRC make some requirement

20 so we aren't having this trouble because we do not

21 want our disposal sites to become a future liability.

22 That was the main issue. We don't want them to become

23 a future liability. The regulation came in to be.

24 So my concern in this area is if you don't

25 set those requirements right, you're going to do just
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1 that. It is going to be a future liability. It's

2 just a matter of the timing. But if you make somebody

3 do the analysis up front, you can greatly reduce the

4 likelihood that that will become a future liability.

5 And so I think that's what the intent of what they

6 wanted to do. It's good practice in terms of safety.

7 I think there's a whole bunch of things that go into

8 why you would want to do it the way we're

9 recommending. But ultimately that's a decision that's

10 made by our high-level decision makers including

11 groups like yourself and whatever it is, it is.

12 MEMBER POWERS: Let me just suggest that

13 maybe you can put together a defense on that 10,000

14 year and the other parts you think you're going to

15 have friction in your public meeting and get Mr. Ryan

16 have another subcommittee meeting and we can be

17 devil's advocate for you and help you on that a little

18 bit.

19 MEMBER RYAN: One part of the 10,000 year

20 thing too is what do you receive? We've heard the

21 arguments if you have uranium 10,000 doesn't make a

22 big difference.

23 MEMBER POWERS: Isn't going to buy you

24 anything.

25 MEMBER RYAN: But if you have some waste
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1 you have that are easily managed within 1,000, but

2 then there's a couple other ones that can get your out

3 of 1,000 and 10,000, is there flexibility in one

4 number. Do you have to have one number? That's to

5 say you can justify one, ten or whatever. So that's

6 a strategy there to think about.

7 MR. ESH: There is some -- as I tried to

8 say, there shouldn't be a burden if, in fact, you say

9 you want to dispose of short-lived waste or very low

10 concentrations of long-lived waste. That technical

11 analysis should be relatively straight forward. This

12 requirement should not be causing you a burden. So

13 what problems are trying to be solved by all the focus

14 on this number? 

15 There's a lot more important things in

16 this regulation that are barely talked about and are

17 much more significant than all the attention that's

18 put on the compliance period. The compliance period

19 is not going to determine whether facilities pass or

20 fail in unto itself. It's the quality of the analyses

21 and the evaluation that's done that will determine

22 whether you make a Type 1 error or Type 2 error or

23 type of decision-making process. 

24 I understand it's something people like to

25 talk about and we spend a lot of energy, but when it's
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1 all said and done, I don't think that's going to be

2 the determining factor of whether the regulation was

3 a good one or not.

4 MEMBER RAY: Well, if you were an

5 applicant and you didn't have just short-lived waste,

6 what difference would it make that you had to look at

7 10,000 years instead of 1,000?

8 MR. ESH: Sorry, say that again, the first

9 part of it?

10 MEMBER RAY: If you were an applicant --

11 MR. ESH: Oh, an applicant, okay.

12 MEMBER RAY: And you didn't have just

13 short-lived waste and you had to meet the 10,000-year

14 requirement instead of 1,000, what would the effect of

15 that be?

16 MR. ESH: In my opinion, because I've done

17 a lot of performance assessment calculations. I've

18 reviewed a lot of performance assessment calculations

19 from all sorts of different groups, internationally,

20 domestically, what have it. There is -- once you set

21 up the calculation and develop the model's analyses,

22 whatever, there is not a huge additional burden to

23 extending the time frame between say 1,000 and 10,000.

24 MEMBER RAY: What is the burden?

25 MR. ESH: There's some burden because some
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1 systems will be different and change over that period

2 of time. So like if you take a site like our complex

3 decommissioning site at West Valley, for instance,

4 high erosion, okay. The model that you might develop

5 for 1,000 years might be quite a bit different than

6 the model that you need to develop for 10,000 years

7 because of that erosion. It changes your land form,

8 your aquifer changes as the land form erodes. It's

9 just an example of that might be a special case where

10 you get a big delta between those time frames.

11 But for the most part, when you put in

12 the expense of collecting your site-specific

13 information for say rainfall and distribution

14 coefficients and plant transfer factors and all that

15 sort of information, that information is not going to

16 be hugely dynamic between 1,000 years and 10,000

17 years.

18 MEMBER RAY: Let me ask about something

19 that may not be as predictable as you're implying to

20 me anyway. And that is changes in the meteorology,

21 global warming, whatever name you want to give to it,

22 things that make erosion different 5,000 years down

23 the road than it is now. Are you having to imagine

24 those things and include them in the analysis?

25 MR. ESH: Yes, so climate is a driving
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1 function of some other process. Basically, the

2 approach that we've taken in the past is anthropogenic

3 effects on climate are too difficult or too uncertain

4 at this point to accurately project their effects into

5 these time frames.

6 MEMBER RAY: Well, that's the thing I

7 think we find most disturbing is that wouldn't be the

8 case. Somebody would say how about an ice age, what

9 about a glacier?

10 MR. ESH: Well, what we do say is the

11 natural cycling of climate has been pretty well known

12 or is reasonably well established and in these waste

13 disposal systems at the longer time, you would want to

14 consider the natural cycling of the climate and for

15 instance, in the application for the disposal facility

16 in Texas, they did just that. But how did they do it?

17 Well, basically at longer times they end up with I

18 think it was a cooler and wetter climate state which

19 is associated with more precipitation, more

20 infiltration and then the associated effects on their

21 system. That's commonly what we've seen. They also

22 did that at Yucca Mountain, for instance, looking at

23 climate states and climate analogs and they analyzed

24 the changes in the system over time.

25 So the natural cycling, we think, it might
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1 change the timing of some of the processes, but the

2 amplitude of the natural cycling is probably just as

3 large or larger than the anthropogenic effects. So as

4 long as you're considering the natural cycling you

5 probably have handled the anthropogenic, even if you

6 don't get the timing exactly right.

7 MEMBER RAY: What you're implying to me is

8 what you're referring to as natural cycling is a

9 bounded, quantifiable thing, not some unknowable.

10 MR. ESH: The fact that we've had

11 repetitive pattern of ice ages and warmer periods like

12 we're in now that you can't accurately predict the

13 exact timing of them, but the relative magnitude and

14 their effects you can to some extent. And it would --

15 there was an interesting show I saw about meteorites

16 and this was in Sweden. When a meteorite hits, it

17 forms a strewn field on the surface. It's basically

18 the patterns of rocks that are dispersed when the

19 meteorite blows up. 

20 There's a meteorite field in Sweden that

21 happened, they dated it and it was a long time ago and

22 it's gone through something like 14 ice ages since

23 then of glaciers coming and then going, coming and

24 then going. Well, the strewn field is still a strewn

25 field. So we have this concept in our mind of you
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1 have this ice age and you have this huge dynamic

2 effects and everything is destroyed and ruined, but

3 the evidence from at least that site says that well,

4 that material still kind of has the general

5 characteristics of what you see if it happened today.

6 So there's that sort of information out

7 there. As I said, it's quantitative information that

8 has to be interpreted qualitatively. That's the

9 bottom line as you're as scientists and engineers are

10 trying to make a decisions that you think is

11 protective using the information you have, considering

12 the uncertainty in the information. I don't think

13 that we should be taking this approach of saying well,

14 we don't know what the risks are, therefore, let's

15 take the action. If you don't know what the risks

16 are, you shouldn't take the action. You should do

17 something else. I don't know what that something else

18 is, but you shouldn't be taking the action if you

19 can't define what the risks are with some reasonable

20 level of confidence.

21 MEMBER BANERJEE: So these ice ages were

22 not so disruptive, these patterns you see, that we

23 could not design some sort of system to withstand

24 that?

25 MR. ESH: I don't think you should be
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1 thinking that way necessarily. This is low-level

2 waste, as I said, and if I had very concentrated long3 lived low-level waste that could cause a problem at

4 the facility was destructed and it was dispersed in

5 the surface, I don't have to necessarily put it at a

6 northern site. I can pick a southern site that

7 doesn't have the climate disruption and put it there

8 and solve the problem that way.

9 MEMBER BANERJEE: That would be prudent.

10 MEMBER RYAN: You pick a southern site

11 because there's no snow and the trucks don't have to

12 worry about the weather and there's lots of practical

13 things about why they tend to be in the southern

14 climes.

15 MR. ESH: I mean we can make regulatory

16 requirements as best we can, but ultimately scientists

17 and engineers have to be making good decisions about

18 these things and the two have to work together, but

19 you have to rely on some judgment for some things.

20 MEMBER BLEY: You know at our last

21 subcommittee meeting, you put a lot of focus on and I

22 forget your buzz word for it, but the system to manage

23 the quality of the analysis. I think that focus there

24 probably would be helpful in the future.

25 MR. ESH: I talked about that a little bit
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1 earlier, but I think we get caught up in that these

2 are computer calculations to produce a number and it's

3 totally what this is not about. I mean ultimately you

4 do need to compare a number to a regulatory

5 requirement, but it's about developing the scientific

6 and technical understanding to justify the number that

7 you come up with. And that's why I said like the

8 emphasis on the compliance period, the emphasis should

9 be on the 99 percent of the work that goes into

10 producing that number, whatever time it is. How do

11 you assure the quality of that information considering

12 that right now all these reviews are done in agreement

13 states and a lot of our agreement states are really

14 stressed in terms of their budgets and their staffing

15 and things like that. How do you ensure the quality

16 of their reviews given the complexity of some of this

17 information? That's the key issue in my mind and I've

18 had some of the licensees have said that to me. You

19 know they said hey, we understand all the things

20 technically that you're talking about in the

21 regulatory requirements and what not, but then we have

22 to kick this over the fence to our agreement state

23 regulators. How do you make sure that they do a good

24 review of it? Because we want a good review. We want

25 to know what our problems are so we can correct them.
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1 That's what the licensing process is about.

2 MEMBER SCHULTZ: It seems like what you've

3 just described in terms of the engineering evaluation,

4 the quality and the overall focus on that long-term

5 range does belong in the performance period. And I

6 think that's appropriate for beyond 1,000 years.

7 Setting the compliance period at 10,000 years, I think

8 opens up a regulatory process to all kinds of issues

9 that engineers can answer, but others will enter into

10 the discussion. And they will not have answers and

11 they will not understand what you understand so well

12 or what we understand so well and I think that causes

13 problems and certainly future issues and near-term

14 issues for the regulatory process.

15 MR. ESH: I understand that concern. I'll

16 go back to what is the experience in that area and the

17 experience is that half of the facilities have been

18 licensed using that approach and another one is under

19 review. So ultimately probably three quarters of the

20 facilities will have been analyzed and licensed using

21 that approach.

22 So whether it's a barrier and causes

23 tremendous problems, I hope we hear from our licensees

24 on that respect. We've heard from them and some of

25 our agreement state regulators and just like I talked
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1 earlier about the diversity of opinion, some of them

2 are in support of 10,000 years or longer and some of

3 them are not.

4 MEMBER SCHULTZ: Good for rulemaking.

5 MEMBER RYAN: Any other comments or

6 questions? 

7 Again, I'd like to thank the staff today

8 for a very formative briefing as we had last time and

9 the insights you shared with us for all your work has

10 been very, very helpful throughout the deliberations.

11 I thank you all very much for your time and your

12 efforts and your insights. It's work that I hold as

13 high-quality work and lots of detailed thinking has

14 gone into it. So we really appreciate it very much.

15 MR. CARRERA: Thank you, Dr. Ryan.

16 CHAIR ARMIJO: I'd like to thank the staff

17 for a very interesting -- we always have good

18 discussions. I appreciate your patience. We're going

19 to break for lunch. I'd like to reconvene at 1:30, so

20 almost a full hour instead of 1:45. Okay?

21 (Whereupon, at 12:32 p.m., the meeting was

22 adjourned, and will reconvene at 1:45 p.m.)

23

24

25
SOARCA 

Peach Bottom Uncertainty Analysis (UA)

ACRS Briefing

Tina Ghosh, PhD

Jonathan Barr

RES/DSA/AAB

July 10, 2013
Agenda

• Background and overall conclusions of UA

• Distribution of results

• Most influential uncertain parameters and 

phenomena for source term and consequences

• Comparison of aleatory (weather) uncertainty to 

epistemic uncertainty

• Separate sensitivity analyses for lower-head 

penetration failures, and habitability criterion 

coupled with dose threshold response models

• Other content in the UA report

• Next steps

2
3

Background

• Best-estimate analysis reports:

– NUREG-1935 Final published November 2012

– NUREG/BR-0359 Rev. 1 published December 2012

– NUREG/CR-7110, Vol. 1, Rev. 1 published May 2013

– NUREG/CR-7110, Vol. 2, Rev. 1 published July 2013
4

Background (2)

• Other supporting reports:

– Best Practices for MELCOR and MACCS2, expected 

late 2013

– NUREG/CR-7161 on Distributions for non-site-specific 

uncertain parameters, published April 2013

• Briefed ACRS on UA approach, initial results, 

and insights – April 2012
5

Overall UA Conclusions

• Peach Bottom UA corroborates SOARCA study 

conclusions

– Public health consequences from severe nuclear 

accident scenarios modeled are smaller than 

previously calculated, and very small in absolute terms

– Delayed releases calculated provide more time for 

emergency response actions such as evacuating or 

sheltering; long-term phase dominates health effect 

risks because emergency response is faster than 

progression to release

– “Essentially zero” early fatality risk projected
6

Overall Conclusions (2)

• A major determinant of source term magnitude and 

health consequences is whether or not Main Steam Line 

(MSL) creep rupture occurs (leads to higher 

consequences)

• Health-effect risks vary sublinearly with source term 

because people are not allowed to return to their homes 

until dose is below habitability criterion

• Analysis confirms known importance of some 

phenomena, and reveals some new phenomenological 

insights

• The use of multiple techniques to post-process Monte 

Carlo results provides better explanatory power of which 

input parameters are most important to uncertainty in 

results
Distribution of Results

7
SRV Stochastic Failures from Replicate 

1 and Single Realizations chosen for 

analysis

8
Fraction of the cesium core inventory 

released to the environment for combined 

(865) results for the PB Unmitigated LTSBO

9
10

Fraction of the iodine core inventory released 

to the environment for combined (865) results 

for the PB Unmitigated LTSBO
Conditional mean, individual latent 

cancer fatality (LCF) risk (per 

event) for combined results (865) 

with LNT model

11

0-10 

miles

0-20 

miles

0-30 

miles

0-40 

miles

0-50 

miles

5

th

percentile 3.1x10-5 4.9x10-5 3.4x10-5 2.2x10-5 1.9x10-5

Median 1.3x10-4 1.9x10-4 1.3x10-4 8.7x10-5 7.1x10-5

Mean 1.7x10-4 2.8x10-4 2.0x10-4 1.3x10-4 1.0x10-4

95th

percentile 4.2x10-4 7.7x10-4 5.3x10-4 3.4x10-4 2.7x10-4

SOARCA UA

Base Case 9.0x10-5 8.3x10-5 5.8x10-5 3.7x10-5 3.0x10-5
Conditional mean, individual 

prompt-fatality risk (per event) for 

combined results (865)

12

0 - 1.3 

miles

0 - 2.5 

miles

0 - 5 

miles

0 - 10 

miles

Median

and 75th

percentile

0.0 0.0 0.0 0.0

Mean 4.5x10-7 8.9x10-8 1.4x10-8 4.8x10-9

95th

percentile 1.9x10-6 3.5x10-8 0.0 0.0
Most Influential Uncertain Input 

Parameters and Associated 

Phenomena

13
14

Most Influential Parameters 

for Source Term Magnitude

• The expected number of SRV cycles before failing to reclose 

(i.e., remain in the fully open position) (SRVLAM)

• The chemical form of cesium (i.e., the amount of cesium as 

CsOH vs. Cs2MoO4) (CHEMFORM)

• The size of the breach in the drywell liner resulting from core 

debris contacting and melting through the liner (FL904A)

• The fractional open area of an SRV after it has failed to reseat 

because of overheating (SRVOAFRAC)

• The time-at-temperature criterion specified for loss of “intact” 

fuel rod geometry (FFC – fuel failure criterion)

• The temperature at which oxidized cladding mechanically fails 

(SC1131_2)

• Whether railroad doors open, and fraction open (RRDOOR, 

RRIDFRAC)
15

Rank 

Regression Quadratic

Recursive 

Partitioning MARS

Final R2--

Variance 

explained 0.61 0.64 0.90 0.66

Input name

R2

inc.

R2

cont. SRRC Si Ti p-val Si Ti p-val Si Ti p-val

SRVLAM 0.50 0.50 -0.72 0.39 0.64 0.00 0.43 0.70 0.00 0.57 0.68 0.00

FL904A 0.53 0.03 0.19 0.01 0.04 0.12 0.06 0.02 0.44 0.00 0.03 0.10

FFC 0.55 0.02 0.19 0.04 0.05 0.31 0.02 0.10 0.00 0.01 0.08 0.00

RRDOOR 0.58 0.03 0.33 0.02 0.10 0.00 0.02 0.03 0.19 --- --- ---

SRVOAFRAC 0.59 0.02 -0.13 0.07 0.19 0.00 0.11 0.33 0.00 0.12 0.27 0.00

CHEMFORM 0.60 0.01 0.09 0.00 0.08 0.38 0.01 0.18 0.00 0.02 0.00 0.87

SC1131_2 0.60 0.01 -0.07 0.02 0.01 0.63 0.00 0.07 0.00 0.00 0.04 0.01

Regression analyses of fraction of 

cesium released over 48 hours
16

Most Influential Parameters 

for Individual LCF Risk

• MACCS2 dry deposition velocity (VDEPOS)

• MELCOR SRV stochastic failure probability 

(SRVLAM)

• MELCOR fuel failure criterion (FFC)

• MELCOR drywell liner melt-through open area 

flow path (FL904A)

• MACCS2 residual cancer risk factor (CFRISK–

Residual)

• MACCS2 residual dose and dose-rate 

effectiveness factor (DDREFA–Residual)
17

Most Influential Parameters for 

Individual Prompt Fatality Risk 

within 2 mile Circular Area

• MACCS2 wet deposition parameter (CWASH1)

• MELCOR SRV stochastic failure probability 

(SRVLAM)

• MELCOR SRV open area fraction (SRVOAFRAC)

• MELCOR DC station battery duration (BATTDUR)

• MACCS2 early health effects threshold and beta 

(shape) factor for red bone marrow (EFFTHR-Red 

Marrow and EFFACB-Red Marrow) 

• MACCS2 linear, crosswind dispersion coefficient 

(CYSIGA)
Aleatory (weather) 

Uncertainty Sensitivity 

Studies

• Comparison of results using SOARCA 

sampling, versus using all available weather 

data in the year

– Miniscule difference

• Comparison of effect of aleatory uncertainty 

versus epistemic uncertainty

– Epistemic uncertainty seems to bound the 

uncertainty stemming from weather, for the LNT 

model

18
19

Weather sampling comparison of the 

conditional, mean, individual LCF risk (per 

event) using the LNT dose-response model 

Distance SOARCA UA

Base Case

All Weather 

Trials

Difference

(%)

10 9.0x10-5 8.9x10-5 0.8%

20 8.3x10-5 8.1x10-5 2.4%

30 5.8x10-5 5.7x10-5 1.7%

40 3.7x10-5 3.7x10-5 1.1%

50 3.0x10-5 3.0x10-5 1.3%
20

Brief source term description for the single 

realizations selected from Replicate 1 (STP08) 

MELCOR Analyses for the aleatory weather 

uncertainty analyses

Scenario

Integral Release Fractions by Chemical Group

Atmospheric 

Release 

Timing

Xe Cs Ba I Te Ru Mo Ce La

Start 

(hr)

End 

(hr)

SOARCA

UA Base

Case

0.981 0.005 0.010 0.025 0.019 0 0 0 0 19.9 48

RLZ062 0.995 0.055 0.014 0.104 0.089 0 0.012 0 0 13.6 48

RLZ170 0.985 0.020 0.022 0.031 0.027 0 0 0.001 0 16.6 48
21

CCDF of conditional, mean, individual LCF risk 

(per event) within the 10-mile circular area for 

aleatory weather uncertainty and the MACCS2 

CAP17 (epistemic uncertainty) analysis
22

CCDF of conditional, mean, individual LCF risk 

(per event) within the 50-mile circular area for 

aleatory weather uncertainty and the MACCS2 

CAP17 (epistemic uncertainty) analysis
23

Separate Sensitivity Analysis 

for Lower-Head Penetration 

Failures
Lower-Head Penetration 

Failure Sensitivity

• Past work considered only “gross creep 

failure” of RPV lower head

• Sensitivity considers penetration failures

– 2 to 38 instrument tubes

– Average of 13.5 tubes

• Sampled additional variables:

– Heat transfer coefficient between penetrations 

and core debris

– Failure temperature

24
Lower-Head Penetration 

Failure Sensitivity (2)

• Penetration failures generally occurred 3 hours 

before the gross lower head failure 

• Relatively insensitive to variations in the sampled 

input parameters

• Relocation of core debris to the reactor cavity 

through penetrations generally began within 6 

minutes of the first penetration failure once 

appreciable molten material resided near the 

penetration 

• The penetrations did not ablate significantly 

25
Lower-Head Penetration 

Failure Sensitivity (3)

• Influence on relative cesium release to the 

environment is potentially large 

– Fractional releases of cesium to the environment 

ranged 0.006 – 0.07, with a mean of 0.04

• Important to note that the penetration modeling 

available in MELCOR does not calculate the 

plugging of an open penetration by freezing melt 

– If this phenomenon were accounted for, penetration 

failures might be immaterial in that the associated 

openings readily reclose

– Such plugging was observed to have occurred in the 

Three Mile Island accident

26
Separate Sensitivity Analysis 

for Habitability Criterion and 

Dose-Threshold Response 

Models

27
28

Radius

(mi)

SOARCA UA Base 

Case Individual LCF 

Risk

0.5 rem/yr

0.1 rem/yr 2 rem/yr

10 9.0x10-5-59% 75%

20 8.3x10-5-30% 34%

30 5.8x10-5-27% 28%

40 3.7x10-5-25% 23%

50 3.0x10-5-25% 21%

Percentage change in conditional mean, 

individual LCF risk per event for the LNT 

dose-response model from variations in 

habitability criterion 
LNT habitability criterion 

sensitivity insights

• Majority of the LCF risk contribution within the 

EPZ resulted from the long-term phase for all 

habitability scenarios

– The higher the habitability criterion, the higher the 

LCF risk as a result of long-term dose within the EPZ

• Majority of the LCF risk for the 0.1 rem/yr 

habitability criterion results from the emergency 

phase

• Most of the risk corresponds to the long-term 

phase for other choices of habitability criterion

29
30

Radius (mi)

SOARCA UA 

Base Case 

Individual LCF 

Risk

0.5 rem/yr

0.1 rem/yr 2 rem/yr

10 8.9x10-7-8.6% 2,600%

20 2.6x10-5-23% 49%

30 1.6x10-5-30% 50%

40 7.7x10-6-37% 57%

50 5.2x10-6-39% 66%

Percentage change in conditional mean, 

individual LCF risk (per event) for USBGR 

dose-threshold (620 mrem/yr) model from 

variations in habitability criterion
Dose threshold models 

habitability criterion 

sensitivity insights

• Most of the doses received during the long-term 

phase are below the dose threshold limit and 

are not counted toward health effects; most of 

the risks are from doses received during the first 

year.

• LCF risks within the EPZ are orders of 

magnitude lower when the habitability criterion 

is below the dose-threshold level

31
Other Content in UA Report

• Separate sensitivity analyses for operator 

action timing (manual depressurization)

• Hydrogen generation insights

• Fukushima comparison

• Stability analysis for results, statistical 

convergence

• Probabilistic analysis methodology

• MELCOR version changes since best-estimate 

analysis was complete, and their effects

• Peer review & ACRS comment resolution

32
Next Steps

• Address office comments – July 2013 

• ANS PSA Conference presentation and papers 

– September 2013 

• Send final NUREG/CR-7155 report for 

publication – Fall 2013 

• NRC research seminar – Fall 2013 

33
 Questions and Comments

34
BACK-UP SLIDES

35
36

Cumulative distribution function of fraction of cesium 

core inventory released to the environment after 48 

hours based on all combined (i.e., 865) results, with 

95% confidence interval over statistical measures
37

CV 200

CV 220 F L012

F L020

CV 220

F L021

F L903

( DW head 

flange failure )

C V2

CV21

10

0

CV 205

F L014

Personnel

access

F L016

CRD hyd . 

pipe chase

F L015

CRD removal

F L904

(DW liner 

melt-through)

F L017

(DW nominal leakage)

F L022

(RB-WW vacuum breaker 

to NE torus corner room)

F L023

(RB-WW vacuum breaker 

to SE torus corner room)

CV 201

CV 202

FL202

F L200

F L910

(Wetwell Hard-Pipe vent

to atmosphere)

SRV Seizure Versus MSL 

Rupture

CV 200

CV 220 F L012

F L020

CV 220

F L021

F L903

( DW head 

flange failure )

C V2

CV21

10

0

CV 205

F L014

Personnel

access

F L016

CRD hyd . 

pipe chase

F L015

CRD removal

F L904

(DW liner 

melt-through)

F L017

(DW nominal leakage)

F L022

(RB-WW vacuum breaker 

to NE torus corner room)

F L023

(RB-WW vacuum breaker 

to SE torus corner room)

CV 201

CV 202

FL202

F L200

F L910

(Wetwell Hard-Pipe vent

to atmosphere)

Main Steam Line Rupture vents

Fission products to drywell

Release to environment via head

Flange failure or drywell liner melt through

SRV Seizure vents fission products

Into wetwell

Wetwell scrubbing prevents release 

To the environment

MSL Rupture

SRV cycles long time

MSIV

SRV sticks open
38

Goals of the 

Uncertainty Analysis

• Develop insight into overall sensitivity of 

SOARCA results to uncertainty in inputs

• Identify most influential input parameters for 

releases and consequences

• Demonstrate uncertainty analysis methodology
Approach

• Focus is on epistemic (state-of-knowledge) uncertainty in 

input parameter values

– Model uncertainty addressed to the extent that some parameters 

represent or capture alternate model effects; or in separate 

sensitivity analyses

– Aleatory (random) uncertainty due to weather is handled in the 

same way as the SOARCA study

• Peach Bottom, unmitigated, long-term station blackout 

scenario chosen

• Scenario definition not changed after Fukushima

– A separate qualitative discussion planned for an appendix

• Looking at uncertainty in key model inputs

– MELCOR parameters

– MACCS2 parameters 39
40

Approach (continued)

• Key uncertain input parameters were identified

• Uncertainty in these parameters propagated in 

two steps using Monte Carlo and Latin 

Hypercube (LHS) sampling:

– A set of source terms generated using MELCOR model

– A distribution of consequence results generated using 

MACCS2 model

• Epistemic sample sets of 300 generated to 

complete a corresponding number of individual 

code runs (Monte Carlo “realizations”) to 

evaluate the influence of the uncertainty on the 

estimated outcome
Approach (continued)

41

• Results reported will include:

– Analysis of source term releases including Cesium and Iodine 

release over time

– Latent cancer fatality risk, with three dose threshold models

– Description of most influential uncertain parameters in study

• Tools used to analyze results include statistical 

regression-based methods as well as scatter plots and 

phenomenological investigation of individual realizations 

of interest

• Guidance solicited from SOARCA peer reviewers on the 

uncertainty analysis plan documenting the approach, 

chosen parameters and distributions; feedback from 

Advisory Committee on Reactor Safeguards
SOARCA Uncertainty 

Analysis

42

Best estimate calculations 

include weather variability in 

the consequences

Probabilistic UA includes both the 

weather variability and the 

uncertainty in the epistemic input 

parameters
Core Team Members

• MELCOR and severe accident progression: Randy 

Gauntt, Kyle Ross, Doug Osborn, Don Kalinich, Mike 

Young, Jeff Cardoni, Andrew Goldmann (SNL); Mark 

Leonard (dycoda); Ed Fuller (NRC)

• MACCS2, consequence analysis and emergency 

response: Nate Bixler, Joe Jones, Doug Osborn (SNL)

• UA methodology: Patrick Mattie, Cedric Sallaberry, Jon 

Helton (SNL); Tina Ghosh (NRC) 

• Consultants for MACCS2 latent health effects modeling: 

Keith Eckerman (ORNL); Tony Huffert (NRC)

43
 Process for Choosing 

Parameters and Distributions

• Core team of staff from SNL and NRC with expertise in 

probability and statistics, uncertainty analysis, and MELCOR 

and MACCS2 modeling for SOARCA

• Subject matter experts (SMEs) provided support in reviews of 

data and parameters

• Approach is based on a formalized PIRT (phenomena 

identification, and ranking table) process.

• Focus on confirming that the parameter representations 

appropriately reflect key sources of uncertainty, are 

reasonable, and have a defensible technical basis

• Attempt to obtain contribution from uncertainty across the 

spectrum of phenomena operative in the analyses, through a 

balanced depth and breadth of coverage

44
MELCOR Uncertain Parameters

45

Sequence Issues

• Battery duration

• SRV stochastic failure rate, 

thermal seizure criteria, and 

open area fraction

In-Vessel Accident Progression

• Main steam line (MSL) creep 

rupture open area fraction

• Zircaloy melt breakout 

temperature

• Molten clad drainage rate

• Fuel failure criterion

• Debris radial relocation time 

constants

Ex-vessel Accident Progression

• Debris lateral relocation time 

constants

Containment & building behavior

• Drywell liner failure flow area

• Drywell head flange leakage 

parameters

• Hydrogen ignition criteria 

(where flammable)

• Railroad doors open fraction

Fission Product release, 

transport, and deposition

• Cesium and Iodine chemical 

forms

• Aerosol deposition parameters
46

MACCS2 Uncertain Parameters

Atmospheric Transport and 

Deposition

• Wet deposition model linear 

coefficient

• Dry deposition velocities

• Dispersion parameters

Emergency planning and 

response

• Shielding factors

• Hotspot and normal 

relocation

• Evacuation delay and speed

Health Effects

• Early health effects

• Latent health effects

o Groundshine dose 

coefficients

o Dose and dose rate 

effectiveness factors

o Inhalation dose 

coefficients

o Cancer mortality risk 

coefficients
47

Probabilistic Uncertainty analysis is an iterative process

Scenario Selection

current MELCOR model/software

current WinMACCS model/software

Inputs & Parameter 

Selection

informal expert elicitation from SMEs 

& Peer Review

Uncertainty Analysis

Framework

MELCOR Uncertainty Engine

MELCOR

MELMACCS

WinMACCS/LHS

Uncertainty Analysis

regression analyses

scatter plots

Single Realization 

phenomenological analysis

Stability Analysis

# realization stability

random seed stability

alt. modeling cases

Iterate

Range of validity

Stability of analysis

Alternative model scenarios

SRV Stochastic

SRV Thermal 

MSL Creep Rupture

Sensitivity Analysis

Address Bugs or Modeling Errors

Analysis Complete
48

SRV Thermal Failures without MSL 

rupture from Replicate 1 and Single 

Realizations chosen for analysis
49

SRV Thermal Failures with MSL creep 

rupture from Replicate 1 and Single 

Realizations chosen for analysis
50

Cumulative distribution function of 

SRVOAFRAC with samples where MSL creep 

rupture indicated for Replicate 1
51

Rank Regression Quadratic Recursive 

Partitioning MARS

Final R2 0.24 0.62 0.63 0.58

Input R2inc. R2

cont.

SRR

C

Si Ti p-val Si Ti p-val Si Ti p-val

CWASH1 0.03 0.03 0.08 0.29 0.76 0 0.15 0.60 0 0.04 0.78 0

SRVLAM 0.07 0.04 -0.10 0.01 0.41 0 0 0.10 0.35 0.01 0.28 0.07

SRVOAFRAC 0.10 0.03 -0.09 0.01 0 1 0.06 0.53 0 0.06 0 1

BATTDUR 0.10 0 -0.03 0 0.13 0.09 0 0.05 0.32 --- --- ---

EFFTHR

Red Marrow

0.15 0.05 -0.12 0 0.18 0.13 0.01 0.52 0 0.02 0.47 0

EFFACB

Red Marrow

0.16 0.01 0.04 --- --- --- --- --- --- 0.01 0 1

CYSIGA 0.18 0.02 0.07 0 0.40 0 --- --- --- 0.04 0.48 0

DLTEVA

Cohort 5 0.19 0.01 -0.07 0.02 0 1 0.07 0.15 0.17 0 0 1

GSHFAC

Normal

0.21 0.02 0.06 --- --- --- --- --- --- 0.01 0.12 0.27

Mean, individual prompt-fatality risk per 

event regression of the MACCS2 Uncertainty 

Analysis for the 2-mile circular area
52

Mean, individual LCF Risk per event regression of 

MACCS2 Uncertainty Analysis using LNT model for 

the 50-mile circular area

Rank Regression Quadratic Recursive 

Partitioning MARS

Final R2 0.52 0.57 0.71 0.54

Input R2inc. R2 cont. SRRC Si Ti p-val Si Ti p-val Si Ti p-val

VDEPOS 0.18 0.18 -0.43 0.09 0.18 0 0.16 0.46 0 0.19 0.39 0

SRVLAM 0.25 0.07 0.26 0.12 0.31 0 0.05 0.29 0 0.05 0.16 0.06

DDREFA

Residual 0.30 0.05 0.24 0.05 0.09 0.07 --- --- --- 0.09 0.09 0.29

Fuel failure 

criterion 0.45 0.03 0.16 --- --- --- 0 0.05 0.07 0 0.01 0.38

FL904A 0.48 0.02 -0.14 0.04 0.08 0 0.05 0.28 0 0.02 0 1

BATTDUR --- --- --- 0.03 0.02 0.46 --- --- --- 0 0.01 0.34

CFRISK

Residual --- --- --- 0 0.04 0.33 0 0.12 0 0.02 0.01 0.37

GSHFAC

Normal

0.34 0.04 0.18 --- --- --- 0 0.03 0.45 0.06 0.05 0.14

CFRISK

Lung

0.37 0.03 0.19 0.01 0.12 0.01 0.04 0.22 0 0.03 0.07 0.28

DDREFA

Lung

0.40 0.03 0.26 0 0.13 0 --- --- --- 0.02 0.11 0

GSHFAC

Evacuation 0.43 0.03 0.16 0.06 0.15 0 0.01 0.23 0 0.04 0.08 0
53

Radius

(mi)

SOARCA UA 

Base Case 

Individual LCF 

Risk

0.5 rem/yr

0.1 rem/yr 2 rem/yr

10 5.6x10-7-5.7% 45%

20 4.4x10-6-12% 40%

30 1.7x10-6-13% 42%

40 7.1x10-7-13% 42%

50 4.5x10-7-13% 42%

Percentage change in mean, individual LCF 

risk per event for the HPS dose-response 

model from variations in habitability criterion 
Low-Level Radioactive Waste Disposal 

(10 CFR Part 61) 

Preliminary Version

Andrew Carrera 

Division of Intergovernmental Liaison and Rulemaking

Office of Federal and State Materials and Environmental 

Management Programs

Andrew.Carrera@nrc.gov, (301) 415-1078

606th Advisory Committee on Reactor Safeguards 

July 10, 2013 
Purpose of the rule: 

• Specify site-specific technical analyses requirements

• Permit development of criteria for waste disposal based 

on the results of these analyses

• Better align the requirements with current health and 

safety standards

2
Proposed Amendments: 

Site-Specific Analyses 

• Performance assessment — Add requirements to demonstrate 

protection of the general population within the 10,000-year 

compliance period (§ 61.41(a)) and to minimize releases of 

radioactivity to the extend reasonably achievable at any time during 

the post-10,000-year period (§ 61.41(b)) 

• Intruder assessment — Add requirements to demonstrate 

protection of inadvertent intruders within the 10,000-year 

compliance period and a stated dose limit (§ 61.42(a)) and to 

minimize exposures to any inadvertent intruder to the extend 

reasonably achievable at any time during the post-10,000-year 

period (§ 61.42(b)) 

3
Proposed Amendments: 

Site-Specific Analyses 

• Long-term analyses — Add requirement to demonstrate 

how the disposal system limits the potential radiological 

impacts from long-lived waste during the post-10,000-

year performance period (§ 61.13 (e))

• Update analyses — Add requirement for updated 

analyses at facility closure (§ 61.28)

4
Proposed Amendments: 

Waste Acceptance 

• Waste acceptance — Add requirements to develop 

waste acceptance criteria, establish waste 

characterization methods, and develop waste 

certification program (§ 61.58)

5
Proposed Amendments: 

Other Supporting Changes 

• Definitions and Concepts— Add new definitions (§ 61.2 

and § 20.1003) and new concepts (§ 61.7)

• Allow the use of up-to-date ICRP dose methodology

• Revise Appendix G to 10 CFR Part 20

6
10 CFR Part 61: 

Preliminary Proposed Rule Language 

 
Preliminary Proposed Rule 

Language: Technical Analyses 

• § 61.41 Protection of the general population from releases 

of radioactivity (revised requirement):

(a) Concentrations of radioactive material that may be released to the general 

environment in ground water, surface water, air, soil, plants, or animals must not result in 

an annual dose exceeding an equivalent of 0.25 milliSievert (25 millirems) to any member 

of the public within the compliance period. Reasonable effort should be made to maintain 

releases of radioactivity in effluents to the general environment as low as is reasonably 

achievable during the compliance period. Compliance with this paragraph must be 

demonstrated through analyses that meet the requirements specified in § 61.13(a).

8
Preliminary Proposed Rule 

Language: Technical Analyses 

• Performance assessment (§ 61.13(a)):

(1) Identifies the features, events, and processes (FEPs)

(2) Examines the effects of these FEPs on the 

performance of the disposal system

(3) Estimates the annual dose to any member of the 

public considering uncertainties, caused by all 

significant FEPs

9
Preliminary Proposed Rule 

Language: Technical Analyses 

• § 61.13 Technical analyses (revised requirements):

(a) A performance assessment that demonstrates that there is reasonable assurance 

that the exposure to humans from the release of radioactivity will meet the performance 

objective set forth in § 61.41(a). A performance assessment shall:

(1) Consider features, events, and processes that might affect demonstrating 

compliance with § 61.41(a). The features, events, and processes considered must 

represent a range of phenomena with both beneficial and adverse effects on 

performance, and must consider the specific technical information required in §§

61.12(a) through (i). A technical basis for either inclusion or exclusion of specific 

features, events, and processes must be provided. Specific features, events, and 

processes must be evaluated in detail if their omission would significantly affect 

meeting the performance objective specified in § 61.41(a). 

(2) Consider the likelihood of disruptive or other unlikely features, events, 

or processes for comparison with the limits set forth 

in § 61.41(a). 

10
Preliminary Proposed Rule 

Language: Technical Analyses 

• § 61.13 Technical analyses (revised requirements):

(a)***

(3) Provide a technical basis for either inclusion or exclusion of degradation, 

deterioration, or alteration processes (e.g., of the engineered barriers, waste form, 

site characteristics) and interactions between the disposal facility and site 

characteristics that might affect the facility’s ability to meet the performance objective 

in § 61.41(a).

(4) Provide a technical basis for models used in the performance assessment such as 

comparisons made with outputs of detailed process-level models or empirical 

observations (e.g., laboratory testing, field investigations, and natural analogs).

(5) Evaluate pathways including air, soil, groundwater, surface water, plant uptake, 

and exhumation by burrowing animals.

11
Preliminary Proposed Rule 

Language: Technical Analyses 

• § 61.13 Technical analyses (revised requirements):

(a)***

(6) Account for uncertainties and variabilities in the projected behavior 

of the disposal system (e.g., disposal facility, natural system, 

and environment).

(7) Consider alternative conceptual models of features and processes that are 

consistent with available data and current scientific understanding, and evaluate the 

effects that alternative conceptual models have on the understanding of the 

performance of the disposal facility.

(8) Identify and differentiate between the roles performed by the natural disposal site 

characteristics and design features of the disposal facility in limiting releases of 

radioactivity to the general population.

12
Preliminary Proposed Rule 

Language: Technical Analyses 

• § 61.41 Protection of the general population from releases 

of radioactivity (new requirement):

(b) Effort shall be made to minimize releases of radioactivity from a disposal facility to 

the general environment to the extent reasonably achievable at any time during the 

performance period. Compliance with this paragraph must be demonstrated through 

analyses that meet the requirements specified in § 61.13(e).

13
Preliminary Proposed Rule 

Language: Technical Analyses 

• Long-term analyses (§61.13(e)):

(1) Applies to disposal site with certain long-lived waste

(2) Minimize exposures to the extent reasonably 

achievable metric

(3) Analyze potential radiological impacts from long-lived 

waste during the post-10,000-year performance 

period

14
Preliminary Proposed Rule 

Language: Technical Analyses 

• § 61.13 Technical analyses (new requirement):

(e) Analyses that assess how the disposal site limits the potential long-term radiological 

impacts, consistent with available data and current scientific understanding. The 

analyses shall be required for disposal sites with waste that contains radionuclides with 

average concentrations exceeding the values listed in table A of this paragraph, or if 

necessitated by site-specific conditions. For wastes containing mixtures of radionuclides 

found in table A, the total concentration shall be determined by the sum of fractions rule 

described in paragraph 61.55(a)(7). The analyses must identify and describe the 

features of the design and site characteristics that will demonstrate that the performance 

objectives set forth in §§ 61.41(b) and 61.42(b) will be met.

15
Preliminary Proposed Rule 

Language: Technical Analyses 

 Table A - Average Concentrations of Long -lived Radionuclides Requiring Performance 

Period Analyses

Radionuclide Concentration (Ci/m3)

1

C-14 0.8

C-14 in activated metal 8

Ni-59 in activated metal 22

Nb-94 in activated metal 0.02

Tc-99 0.3

I-129 0.008

Long-lived alpha-emitting nuclides2 103

Pu-241 3503

Cm-242 2,0003

1 Values derived from § 61.55 Class A limits .

2

Includes alpha-emitting transuranic nuclides as well as other long -lived alpha-emitting 

nuclides.

3 Units are nanocuries per gram.

16
Preliminary Proposed Rule 

Language: Technical Analyses 

• § 61.42 Protection of inadvertent intruders (revised 

requirement):

(a) Design, operation, and closure of the land disposal facility must ensure protection of 

any inadvertent intruder into the disposal site who occupies the site or contacts the 

waste at any time after active institutional controls over the disposal site are removed. 

The annual dose must not exceed 5 milliSieverts (500 millirems) to any inadvertent 

intruder within the compliance period. Compliance with this paragraph must be 

demonstrated through analyses that meet the requirements specified in § 61.13(b).

17
Preliminary Proposed Rule 

Language: Technical Analyses 

• Intruder assessment (§ 61.13(b)):

(1) Assumes that an inadvertent intruder occupies the 

site after institutional controls are ineffective and 

engages in activities that might unknowingly expose 

the inadvertent intruder to radiation from the waste.

(2) Examines the capabilities of intruder barriers.

(3) Estimates the potential annual dose by considering 

associated uncertainties.

(4) Dose criterion set for intruder (500 mrem/yr).

18
Preliminary Proposed Rule 

Language: Technical Analyses 

• § 61.13 Technical analyses (revised requirements):

(b) Inadvertent intruder analyses that demonstrate there is reasonable assurance that: 

(1) the waste acceptance criteria developed in accordance with § 61.58 will be met, 

(2) adequate barriers to inadvertent intrusion will be provided, and 

19
Preliminary Proposed Rule 

Language: Technical Analyses 

• § 61.13 Technical analyses (revised requirements):

(b)***

(3) any inadvertent intruder will not be exposed to doses that exceed the limits set 

forth in § 61.42(a) as part of the intruder assessment. An intruder assessment shall:

(i)Assume that an inadvertent intruder occupies the disposal site at any time during 

the compliance period after the period of institutional controls ends, and engages in 

normal activities including agriculture, dwelling construction, resource exploration or 

exploitation (e.g., well drilling), or other reasonably foreseeable pursuits that 

unknowingly expose the intruder to radiation from the waste.

(ii) Identify adequate barriers to inadvertent intrusion that inhibit contact with the 

waste or limit exposure to radiation from the waste, and provide a basis for the time 

period over which barriers are effective.

(iii) Account for uncertainties and variabilities.

20
Preliminary Proposed Rule 

Language: Technical Analyses 

• § 61.42 Protection of inadvertent intruders (revised 

requirements):

(b) Effort shall be made to minimize exposures to any inadvertent intruder to the extent 

reasonably achievable at any time during the performance period. Compliance with this 

paragraph must be demonstrated through analyses that meet the requirements specified 

in § 61.13(e).

21
Preliminary Proposed Rule 

Language: Technical Analyses 

• § 61.13 Technical analyses (revised introductory language):

The specific technical information must also include the following analyses needed to 

demonstrate that the performance objectives of subpart C of this part will be met. 

Licensees with licenses for land disposal facilities in effect on the effective date of this 

subpart must submit these analyses at the next license renewal or within 5 years of the 

effective date of this subpart, whichever comes first. 

22
Preliminary Proposed Rule 

Language: Waste acceptance 

• Waste acceptance (§ 61.58):

(1) develop waste acceptance criteria

(2) establish waste characterization methods

(3) develop waste certification program

23
Preliminary Proposed Rule 

Language: Waste Acceptance 

• § 61.58 Waste acceptance (new requirements):

(a) Waste acceptance criteria. Each applicant shall provide, for approval by the 

Commission, criteria for the acceptance of waste for disposal that provide reasonable 

assurance of compliance with the performance objectives of subpart C of this part. 

Waste acceptance criteria shall specify, at a minimum, the following:

(1) Allowable activities and concentrations of specific radionuclides. Allowable 

activities and concentrations shall be developed from the technical analyses required 

by either § 61.13 for any land disposal facility or the waste classification requirements 

set forth in § 61.55 for a near-surface disposal facility.

24
Preliminary Proposed Rule 

Language: Waste Acceptance 

• § 61.58 Waste acceptance (new requirements):

(a) * * *

(2) Acceptable wasteform characteristics and container specifications. The 

characteristics and specifications shall meet the minimum requirements for waste 

characteristics set forth in § 61.56(a) for all waste, and the requirements in § 61.56(b) 

for waste that requires stability to demonstrate compliance with the performance 

objectives of subpart C of this part.

(3) Restrictions or prohibitions on waste, materials, or containers that might affect the 

facility’s ability to meet the performance objectives in subpart C of this part.

25
Preliminary Proposed Rule 

Language: Waste Acceptance 

• § 61.58 Waste acceptance (new requirements):

(b) Waste characterization. Each applicant shall provide, for Commission approval, 

acceptable methods for characterizing the waste for acceptance. The methods shall 

identify the characterization parameters and acceptable uncertainty in the 

characterization data. The following information, at a minimum, shall be required to 

characterize waste:

(1) Physical and chemical characteristics;

(2) Volume, including the waste and any stabilization or absorbent media;

(3) Weight of the container and contents;

(4) Identities, activities, and concentrations;

(5) Characterization date;

(6) Generating source; and

(7) Any other information needed to characterize the waste to demonstrate that the 

waste acceptance criteria set forth in § 61.58(a) are met.

26
Preliminary Proposed Rule 

Language: Waste Acceptance 

• § 61.58 Waste acceptance (new requirements):

(c) Waste certification. Each applicant shall provide, for Commission approval, a 

program to certify that waste meets the acceptance criteria prior to shipment to the 

disposal facility. The certification program shall:

(1) Designate authority to certify and receive waste for disposal at the disposal facility.

(2) Provide procedures for certifying that waste meets the waste acceptance criteria.

(3) Specify documentation required for waste acceptance including waste 

characterization, shipment (including the requirements set forth in appendix G of 10 

CFR part 20), and certification.

(4) Identify records, reports, tests, and inspections that are necessary to comply with 

the requirements in § 61.80.

(5) Provide approaches for managing waste that has been certified as meeting the 

waste acceptance criteria in a manner that maintains its certification status.

27
Preliminary Proposed Rule 

Language: Waste Acceptance 

• § 61.58 Waste acceptance (new requirements):

(d) Licensees with licenses for land disposal facilities in effect on the effective date of 

this subpart shall comply with the requirements of paragraphs (a), (b), and (c) of this 

section at the next license renewal or within 5 years of the effective date of this subpart, 

whichever comes first.

(e) For license applicants, the waste acceptance criteria will be incorporated into the 

facility license. For licensees with licenses for land disposal facilities in effect on the 

effective date of this subpart, upon Commission approval and if otherwise consistent 

with applicable State and Federal law, the NRC will issue an amendment to the license 

incorporating the waste acceptance criteria into the existing license.

28
Preliminary Proposed Rule 

Language: Waste Acceptance 

• § 61.58 Waste acceptance (new requirements):

(f) Each licensee shall annually review the content and implementation of the waste 

acceptance criteria, waste characterization methods, and certification program

(g) Applications for modification of approved waste acceptance criteria must be filed in 

accordance with § 61.20

(h) In determining whether waste acceptance criteria will be approved, the Commission 

will apply the criteria set forth in § 61.23

29
Preliminary Proposed Rule 

Language: Other Changes 

• Definitions(§ 61.2)

• Concepts(§ 61.7)

• “Requirements for Transfers of Low-Level Radioactive 

Waste Intended for Disposal at Licensed Land Disposal 

Facilities and Manifests” Appendix G to 10 CFR Part 20

• “Uniform Low-Level Radioactive Waste Manifest” NRC 

Forms 540 and 541

30
Preliminary Proposed Rule 

Language: Other Changes 

• § 61.2 Definitions (new definition):

Long-lived waste means waste containing radionuclides (1) where more than 10 percent 

of the initial activity of a radionuclide remains after 10,000 years (e.g., long-lived parent), 

(2) where the peak activity from progeny occurs after 10,000 years (e.g., long-lived 

parent – short-lived progeny), or (3) where more than 10 percent of the peak activity of a 

radionuclide (including progeny) within 10,000 years remains after 10,000 years (e.g., 

short-lived parent – long-lived progeny). 

31
Preliminary Proposed Rule 

Language: Other Changes 

• § 61.2 Definitions (new definition):

Compliance period is the time during which compliance with the performance objectives 

specified in §§ 61.41, 61.42, and 61.44 must be demonstrated. This period ends 10,000 

years after closure of the disposal facility.

Performance period is the timeframe established considering waste and site 

characteristics to evaluate the performance of the site after the compliance period

32
Preliminary Proposed Rule 

Language: Other Changes 

• § 61.2 Definitions (new definition):

Waste means those low-level radioactive wastes containing source, special nuclear, or 

byproduct material that are acceptable for disposal in a land disposal facility. For the 

purposes of this definition, low-level radioactive waste means radioactive waste not 

classified as high-level radioactive waste, transuranic waste, spent nuclear fuel, or 

byproduct material as defined in paragraphs (2), (3), and (4) of the definition of 

Byproduct material set forth in this section. Consistent with the National Defense 

Authorization Act for Fiscal Year 2013, low-level radioactive waste also includes 

radioactive material that, notwithstanding Section 2 of the Nuclear Waste Policy Act of 

1982, results from the production of medical isotopes that have been permanently 

removed from a reactor or subcritical assembly, for which there is no further use, and 

the disposal of which can meet the requirements of this part.

33
Preliminary Proposed Rule 

Language: Other Changes 

• § 61.7 Concepts (new concept):

(e) ***

(2) Institutional control of access to the site is required for up to 100 years. This 

permits the disposal of Class A and B waste without special provisions for intrusion 

protection, since these wastes contain types and quantities of radioisotopes that 

generally will decay during the 100-year period and will present an acceptable hazard 

to the intruder. However, waste that is Class A under 61.55(a)(6) may not decay to 

acceptable levels in 100 years. For waste classified under 61.55(a)(6), safety is 

provided by limiting the quantities and concentrations of the material consistent with 

the disposal site design. Safe disposal of waste classified under 61.55(a)(6) is 

demonstrated by the technical analyses and compliance with the performance 

objectives. The government landowner administering the active institutional control 

program has flexibility in controlling site access, which may include allowing 

productive uses of the land provided the integrity and long-term performance of the 

site are not affected.

34
Preliminary Proposed Rule 

Language: Other Changes 

• § 61.7 Concepts (new concept):

(f) ***

(3) During the period when the final site closure and stabilization activities are being 

carried out, the licensee is in a disposal site closure phase. Following that, for a 

period of five years, the licensee must remain at the disposal site for a period of 

postclosure observation and maintenance to assure that the disposal site is stable 

and ready for institutional control. The period of postclosure observation and 

maintenance is used to ensure that the final site closure and stabilization activities 

have not resulted in unintended instability at the disposal site. The Commission may 

approve shorter or require longer periods if conditions warrant. At the end of this 

period, the licensee applies for a license transfer to the disposal site owner.

35
Preliminary Proposed Rule 

Language: Other Changes 

• § 61.7 Concepts (new concept):

(g) Implementation of dose methodology. The dose methodology used to demonstrate 

compliance with the performance objectives of this part shall be consistent with the dose 

methodology specified in the standards for radiation protection set forth in part 20 of this 

chapter. After the effective date of these regulations, applicants and licensees may use 

updated factors incorporated by the Environmental Protection Agency into federal 

radiation protection guidance or may use the most current scientific models and 

methodologies (e.g., those accepted by the International Commission on Radiological 

Protection) appropriate for site-specific circumstances to calculate the dose. The 

weighting factors used in the calculation of the dose must be consistent with the 

methodology used to perform the calculation. 

36
Preliminary Proposed Rule 

Language: Other Changes 

• Appendix G to Part 20 -- Requirements for Transfers of 

Low-Level Radioactive Waste Intended for Disposal at 

Licensed Land Disposal Facilities and Manifests (revised 

requirements):

II. * * *

An authorized representative of the waste generator, processor, or collector shall 

certify by signing and dating the shipment manifest that the transported materials 

meet the waste acceptance criteria for disposal; are properly classified, described, 

packaged, marked, and labeled; and are in proper condition for transportation 

according to the applicable regulations of the Department of Transportation and the 

Commission. A collector who signs the certification is certifying that nothing has been 

done to the collected waste that would invalidate the waste generator's certification.

. 

37
Preliminary Proposed Rule 

Language: Other Changes 

• Appendix G to Part 20 -- Requirements for Transfers of 

Low-Level Radioactive Waste Intended for Disposal at 

Licensed Land Disposal Facilities and Manifests (revised 

requirements):

III. * * *

A. * * *

1. Prepare all wastes according to the land disposal facility’s criteria for waste 

acceptance developed in accordance with § 61.58 of this chapter;

2. Label each disposal container (or transport package if potential radiation hazards 

preclude labeling of the individual disposal container) of waste in accordance with §

61.57 of this chapter;

3. Conduct a quality assurance program to assure compliance with the land 

disposal facility’s criteria for waste acceptance that has been developed in 

accordance with § 61.58 of this chapter (the program must include management 

evaluation of audits);

. 

38
Preliminary Proposed Rule 

Language: Other Changes 

• Appendix G to Part 20 -- Requirements for Transfers of 

Low-Level Radioactive Waste Intended for Disposal at 

Licensed Land Disposal Facilities and Manifests (revised 

requirements):

III. * * *

C. * * *

3. Prepare all wastes according to the land disposal facility’s criteria for waste 

acceptance developed in accordance with § 61.58 of this chapter;

4. Label each package of waste in accordance with § 61.57 of this chapter;

5. Conduct a quality assurance program to assure compliance with the land 

disposal facility’s criteria for waste acceptance that has been developed in 

accordance with § 61.58 of this chapter (the program shall include management 

evaluation of audits);

39
Preliminary Proposed Rule 

Language: Other Changes 

• Uniform Low-Level Radioactive Waste Manifest (revised 

forms):

NRC Form 540 — Revised certification statement 

NRC Form 541 — Revised to allow licensees to indicate 

the use of WAC

40
Next Steps ... 

• If Commission approves of rulemaking package ... 

• Publish in Federal Register later in calendar year 

(Fall/Winter 2013)

• Conduct public meetings in FY2014 (locations and 

dates yet to be determined)

• Deliver final rulemaking package to Commission in 

late calendar year 2014

41
Low-Level Radioactive Waste Disposal 

(10 CFR Part 61) 

Deborah Jackson, Deputy Director

Division of Intergovernmental Liaison and Rulemaking

Office of Federal and State Materials and Environmental 

Management Programs

Deborah.Jackson@nrc.gov, (301) 415-7278

606th Advisory Committee on Reactor Safeguards 

July 10, 2013 
Why are we here 

today:

• Provide update of Part 61 Low-Level Radioactive Waste 

Disposal rulemaking

• ACRS briefings

 Subcommittee (December 2009, June 2011, August 2011, April 2013, 

and June 2013)

 Full Committee (March 2010, July 2011, and September 2011)

• Preliminary “Low-Level Radioactive Waste Disposal 

(10 CFR Part 61)” Federal Register notice

2
Commission Directions: 

• SRM-SECY-08-0147 and SRM-SECY-10-0043

Require site-specific analysis for disposal of large quantities of DU, specify criteria 

needed for analysis, develop supporting guidance, and incorporate blending issue 

into the existing rulemaking for DU.

• SRM-COMWDM-11-0002/COMGEA-11-0002

1. Allowing licensees the flexibility to use ICRP dose methodology;

2. A two tiered approach that establishes a compliance period that covers the 

reasonably foreseeable future and a longer period of performance that is not a 

priori;

3. Flexibility for disposal facilities to establish site-specific waste acceptance 

criteria based on the results of the site’s performance assessment and intruder 

assessment;

4. A compatibility category...that ensures alignment between the States and 

Federal government on safety fundamentals, while providing the States with 

the flexibility to determine how to implement these safety requirements.

3
Today’s topics and 

presenters: 

Topic Presenter

Preliminary Proposed Rule: Low-level 

Radioactive Waste Disposal (10 CFR Part 61)

Andrew Carrera, 

DILR

4