ML061370676
| ML061370676 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 05/01/2006 |
| From: | NRC/OGC |
| To: | Atomic Safety and Licensing Board Panel |
| Byrdsong A T | |
| References | |
| 50-271-OLA, ASLBP 04-832-02-OLA, RAS 11605 | |
| Download: ML061370676 (32) | |
Text
May 1,2006 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of ENTERGY NUCLEAR VERMONT YANKEE,
)
Docket No. 50-271 -0LA LLC and ENTERGY NUCLEAR OPERATIONS, INC.
)
ASLBP NO. 04-832-02-OLA (Vermont Yankee Nuclear Power Station)
NRC STAFF'S ANSWER TO NEW ENGLAND COALITION'S REQUEST FOR LEAVE TO FILE NEW CONTENTIONS
1 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION
+ + + + +
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS (ACRS)
SUBCOMMITTEE ON POWER UPRATES
+ + + + +
WEDNESDAY, NOVEMBER 30, 2005 The meeting was convened in Room T-2B3 of o
White Fl.$nt North, 11545 Rockville Pike, Rockville, Maryland, at 8:30 a. m.
MEMBERS PRESENT :
RICHARD S. DENNING, Chairman THOMAS S. KRESS VICTOR H. RANSOM JOHN D. SIEBER GRAHAM B. WALLIS ACRS STAFF PRESENT:
RALPH CARUSO, ACRS Staff ACRS CONSULTANTS PRESENT:
GRAHAM M. LEITCH SANJOY BANERJEE NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINQTON, D.C. 20005-3701 www.nealrgms.com
293 CHAIRMAN DENNING; Please make sure you speak into the nic and identify yourself.
M R. HOPENFELD: My name is Joe Hopenfeld.
I'm a consultant to New England Coalition.
I'll be very, very brief because I spoke for half an hour a couple of weeks ago. Let me repeat my concern.
First, very simple. What happens to a damaged dryer that is exposed to DBA loads? I'd like to remind you, and I think it was mentioned here by Entergy, that these plants were designed to withstand DBA. So it's true the computer codes that were used 40 years ago are a little bit different than the computer model that we're using today.
And based on my experience with PWRs, you'll find new things, new loads under DBA condition that you didn't see before. Obviously they have not at that time considered it a dryer that contains certain distribution of cracks of unknown size and unknown location.
That issue should be ad&essed, and-I I
haven't heard it discussed, only very briefly.
The second issue, and I can go through this very, very quickly, has to do with the iodine spike or iodine releases. We heard this presentation NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE.. N.W.
(202) 2-WASHINGTON, D.C. 2OCQS-3701 www.nealrgms.com
294 in the afternoon, and I haven't heard anything said about the iodine uncertainty.
There is a generic issue that is unresolved.
When you operate with EPU, under EPU conditions, the flow rates are higher.
So the concentration of iodine is lower, and if you remember or you can go back to the database and you'll see when the concentration is lower, there's a potential for a much higher iodine spike, and I'm nottalking factor of two or three. I'm talking an order of magnitude.
So are we. asking ourselves are we meeting the 10 CFR 100 or the 10, what is it, 50.693 That issue hasn't been even touched on, and I think we have to assure ourselves that under the EPU conditions you meet the requirement, the legal requirements..
A I I ~
what I would like to remind you, that the database on which the iodine spike i s based.:on,'
it's purely empirical, and it is not -- you cannot extrapolate the directive to the way I understand it was done.
It wasn't described in the presentation today, but from reading the SER, I believe that they're just plain extrapolated directly,: and I think that issue should be addressed because you cannot assure yourselves that we meet the criteria.
NOW, I don't know how far are we for the NEAL R. GROSS COURT REPORTERS AND TRANSCRlBERS 1323 RHOOE ISLAND AVE., N.W.
(202) 234-4433 WASHINOTON, D.C. 20006.3701 www.nealrgross.mm
1 5 REM or whatever it is in the control room.
The numbers were not presented. They were not in the SER.
So I don't know how far we are, but I've looked at 1
some numbers in other plants, and there was no order 1
of magnitude cushion in there. They were very, very 1
much closed.
So you really have to look at it. It's not an academic issue if you really want to meet the legal requirements. It's not a safety issue, but it's an issue that should be addressed.
The last one has to do with the delta. P across the screen, and one thing that bothered me a little bit, we have some experiments at Los Alamos.
We have some experiments at W. We have some experiments at EPRI, and for a person that, you know, is kind of removed from that, it's very difficult to see how all of that matches together.
In addition to this, I keep hearing the word nconservatism.n However, the conservatism that you're talking about is based on data which was obtained in '96 by weighing the sludge in the pool.
But now what happens to all the sludge that you have during blow-down? What happened to all of the crud and the rust that you get in the drywall that's coming down there?
NEAL R. GROSS COURT REPORTERS AND TAANSCAIBEAS 1323 RHODE ISLAND AVE., N.W.
(202)
WASHINGTON, D.C. 20005-3701 www.nealrgross.com
296 But more important than that, the SER states that the conductivity of the coolant is different, and obviously the particle size, particle distribution is going to be affected by the pH.
So it's not really a conservative kind of approach.
That's ridiculous, but conservative approach would be to take a one-eighth of an inch fiberglass and put it on the screen and take a spray gun and shoot it with particles.
That would be conservative, and then work yourself back.
There's no modeling at all.
There's absolutely no understanding how these pieces come together. They just -- they're somewhere there, but you know, there's some insight.
Well, I have absolute zero insight as to how these things go together. So I know you have a lot of flow area, and that's good, but that clearly is not sufficient.
NOW, with regard to another comment I made last time, it had to do with flow acceleration and corrosion. I think answers were clear. The gentleman that was sitting here asked the question, and the question was answered with regard to velocity and the fact that you're going to increase the scope of your inspection probably will take careof it, but i t i s a NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINQTON, D.C. -1 wwwnealrgrow.com
297 potential problem because you're running 100 feet or 200 feet per second with some particles in there. So basically, these are the four issues that I am sort of repeating myself.
I CHAIRKAN DENNINO:
Do we have any questions?
Let me ask one question, and that is with regard to your first concern, which is in additional accident loads, it looked to me like as far as local loads that they really aren't changed very much, and I was wondering whether, you know, it was EPU or whether it's -- that even though the power is up, the blow-down looks awfully similar, and I was just wondering was there a particular accident scenario that was of concern to you that would --
MR. HOPENFELD: Well, I think I just went on a gut feeling that we are talking about increasing power. I know you're going to be choked on one side, but as it was pointed out, you're going to'run in for a long period of time.
Really the question is: are you going'to excite some new vibrations in that dryer during that different conditions? And you've got to address that.
Because if you do, there was a case. I forgot where it was in Florida. I just don't remember the case, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINOTON, D.C. 20006-3701 www.nea)rgnxs.com
where we did have, I think, a valve on the main steam line lifted and excited very, very strong vibrations.
So you've got to look at it.
You just can't say it's not there.
How different it is, I mean, the flow is choked, and I don1 t know what the peer does to it, but I think you have to realize really again going back to what the calculations tell you.
The calculations we had 40 years ago are not that good, again, based on the PWR. If you go into more detailed modeling, you may find out.
I don't know how the temperature is affecting it. Temperatures may not be different, but the natural frequency of the dryer may change, too.
So how to hold that thing together, somebody has got to look,.and I haven't even heard it mentioned to' you running into PRA and CDF, but you've got.to address the physics first.
CHAIRMAN DEN'ING ;
.. Thank ':ydu
- .very'.
much...
/
?
I.,.
1, '.
1 PARTICIPANT: Are there ianymore jcommeht8?
/
3 I
j I
1;:;:;
MR. ATHERTON:
My n+d!'"j~is':~eter
'James 1 : : ;
Atherton.
I'm here primarily 'representing the I
interests of the public, I
I 1
I And I have a few comments k8d like to make, and 1'11 start out with an overview that has me NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) mM4X3 WASHINOTON, D.C. 20005-3701 w.nealrgrrws.m
outstanding issues in a matter that's coming to the full committee for hearing and whether maybe that full committee meeting maybe wouldnl t be proper to postpone that until these issues were properly addressed.
And I thank you for permitting me to make these torments.
CHAIRMAN DENNING: Thank you very much.
MR. ATHERTON: Are there any questions?
I I CHAIRMAN DENNING :
Any
- comments, I I questions?
(No response.)
CHAIRMAN DENNING: Thank you.
I I Are there any other members of the public
- 1) that want to make a presentation? Yes, please.
MR. SHADIS: Good afternoon. My name is Raymond Shadis.
I'm representing New England I I Coalition.
Thank you for the opportunity to comment.
I'll try to make this quite brief. As I remarked to one member of the committee earlier today, there's too much to say.
So I'll be brief.
We will try to provide some additional written comments, and I'll try to do that in outline form so that they're accessible and usable for your purposes.
I would like to comment, and I hope that NEAL R. GROSS COURT REPOFflERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202)
WASHINQTW, D.C. 20006-3701 w.nealrgross.com
the committee in its review will comment on the process. There are all of the technical specifics, and there are a number of things that jumped out today, but largely the great concern here is with the I
process.
From October, beginning of October forward, it really seemed as if the technical review was being driven by a calendar that. was set for reasons other than technical review. We suddenly had proposed dates for ACRS to review this project, &d a last minute rush of RAIs and SER and, you know, we're really not done with that process yet.
And it does seem to be backwards, that all things considered, if safety were the first concern, that that first concern for safety would have it that as the technical issues were resolved, the calendar would then be set in accordance with anticipating the end of resolving those issues, not the other way around.
A So there1 s that connnent. Also, one thing that popped out today, earlier today, was the segmented licensing actions that have gone forward in support of EPU. In June of -- yeah, I think it was in June, late spring of 2003, we have copies of NRC staff correspondence wondering if it is valid for this NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINQTON, D.C. 20005-3701 www.nealrgrcss.com
licensee to separately submit their ARTS MELLA (phonetic) application, their AST application, and the extended power uprate application, and whether or not for legitimate consideration they should not all have been submitted together.
When we had a presenter from NRC today talking about the alternate source term credit for dry well spray capture of Iodine 131, one of the committee members put their finger right on it because, hey, wait a minute. We're taking credit for using this spray system.
On the other hand, we have some constraints about not using it.
You know, this is among one of those many little issues that's got to be floating around in the mind of an operator.
Comes the time when you are under accident constraints, and had AST and the EPU been handled together in one application, people might have meshed those two concerns and properly addressed them, and I guess our concern is how many other technical issues are floating out there where there is conflict and contradicting information that is bouncing around among these three different applications.
And I just very quickly want to comment on one other item that you have all been asked to consider by the State of Vermont initially, and that NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHOOE ISLAND AVE., N.W.
(202) 2344433 WASHINQTON. D.C. m5-3701
~. n e 8 l r g r o s ~. c ~ m
is the State of Vermont in requesting an independent engineering assessment of Vermont Yankee as prerequisite to upgrade stated that in their letter of request, their belief that the ACRS would consider any such examination in the course of its review of the uprate.
And I know that you've gone there, given that you scheduled that into the two meetings that you held in Brattleboro.
I just want to give a little background on the origin of that engineering team inspection-that NRC offered as a substitute for the independent engineering assessment that was requested by the Vermont Public Service Board.
This is SECY Letter 040071, dated April 29th, 2004, and this letter spells out the proposed program for the engineering team inspection. It is entitled "Proposed Program to Improve the Effectiveness of Nuclear Regulatory Corranission Inspections of Design Issues:
And this is from William Travers, Executive Director of Operations.
And Mr. Travers reports that in order to better understand the degree to which NRC inspections and licensee self-assessment efforts have been effective in identifying design issues, the staff reviewed the last three years
' of NEAL R. GROSS COURT REWRTERS AND TRANSCRIBERS 1323 RHOOE ISLAND AVE., N.W.
(202) 234+m WASHINQTON. D.C. 20005-3701 nrnrw.nealrgross.com
3 12 data from the reactor oversight process, and here's what he says.
And I think it's interesting; it's instructive.
I
- Of the 17 greater than green design 1
engineering issues that fell within the scope of this I
review, 11 were NRC identified, two were licensee identified, and four were.self-revealing.' Love it.
- Of the 11 NRC identified issues, seven involved issues that had previouslybeen recognizedby the licensee, but whose significance the licensee had not recognized. Three of the NRC identified issues were associated with fire protection, an area not typically covered in NRC design inspections. Only one of the NRC identified issues was identified as a result of an NRC design inspection."
And it takes me back to parochial school when we had to do all of the taking away and putting back of numbers in any sequence.
If we had the blackboard up here, we could come down and understand that of 17 greater than green design engineering issues, only one was identified as a result of an NRC design engineering inspection.
So does the program need improvement is the question they were trying to answer, the question they were struggling with.
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 2 a 4 3 3 WASHINGTON, D.C. 200053701 HnvwmalrgrOsS.com
NOW, the scale of the independent engineering assessment requested by the State of Vermont was for four people, four weeks, or about 640 hours0.00741 days <br />0.178 hours <br />0.00106 weeks <br />2.4352e-4 months <br /> of inspection time, and in this letter with respect to the proposed engineering team inspection, Mr.
Travers
- reports,
'Overall, the prototype inspection module is more resource intensive and would require about 700 hours0.0081 days <br />0.194 hours <br />0.00116 weeks <br />2.6635e-4 months <br /> of direct inspection versus the current allocation of approximately 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> for the safety system design inspection.'
And it doesntt take very long in thinking about it before one realizes that the inspection that was done wrapped in the routine periodic design basis inspection, the one that yielded one finding in 17, that same inspection.
So where Vermont was asking for inspection on the scale of 640 hours0.00741 days <br />0.178 hours <br />0.00106 weeks <br />2.4352e-4 months <br />, here we have NRC proposing to give them 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of specialized inspection added to the normal 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> that they do. The 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br /> is taken off the board, and what is put back on is 700. So basically a net gain of 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br />.
On July lst, 2005, SECY Paper 050118 was issued by Luis Reyes, Executive Director, and again, it is instructive, and it goes eventually right to this EPU review, my humble opinion.
NEAL R GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISUND AVE., N.W.
(202)
WASHINQTON, D.C. 20006-3701 www.nealrgross.m
314 The results, and he's speaking now about four pilot inspections that were done, and Vermont Yankee was one of those pilot inspections.
'The results of the pilot inspections appear to indicate that latent design and engineering issues mostly of very low safety significance persist at operating reactors.
The pilot inspections resulted in 29 inspection findings.'
And to Vermont Yankee, the next page, 'the staff has reviewed the results of the Vermont Yankee inspection and has concluded that the current power uprate inspection procedure should be enhanced. -In addition, a process should be developed to better integrate the inspection and NRR. technical review process for power uprates and other
- important license amendment requests.
These conclusions are based primarily on the identification of several issues during the Vermont Yankee inspection. These issues included the acceptability of the licensee's power uprate submittals with respect to station blackout rule, motor operated valve testing, certain operator response times, and certain assumptions in accident analyses. The staff believes it unlikely that these inspection identified issues would have been identified by subsequent NRR technical reviews NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
@02) 234-4433 WASHINOTON, D.C. 20005-3701 w ~ w n s a l r g l 0 6 s. ~
315 becausen -- and this echoes the last two days because I heard this, and this is parenthetical and I'm 1
interjecting this.
1 Over the last two days, I heard NRC staff say again and again 'the licensee says, " " the licensee reports," "the licensee tells us," "the licensee has it in their application."
"The staff believes it unlikely that these inspection identified issues would have been identified by subsequentNRRtechnica1 reviews because the NRR technical reviews rely primarily on licensee submitted documentation."
And this I could have written myself.
"The staff, therefore, believes that a detailed inspection is a good complement to the NRR technical review in this area:
Finally, there is a table included in of that letter, and it yields that Vermont Yankee was accorded a total of 910 hours0.0105 days <br />0.253 hours <br />0.0015 weeks <br />3.46255e-4 months <br /> of direct inspection. This is an addition of.410 hours0.00475 days <br />0.114 hours <br />6.779101e-4 weeks <br />1.56005e-4 months <br /> not to the nominal 500 that's part of the vanilla periodic inspection.
So what the State of Vermont asks for was a very special inspection to confirm the conditions of the plant, to provide some indication of future plant NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE IslAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20006-3701 www.nealrgross.com
316 reliability, to confirm, I think -- maybe I'm putting a little interpretation on this -- to confinn NRC's assumption that their normal inspection regimen provides sufficient assurance that the plant is in conformance with its design basis.
And what they got instead was a warmed over portion of their normal inspection regimen with a topping, if you will, and definitely not what they requested.
I will be submitting written comments because there is additional material with respect to the contrast between the scale and the scope and the purposes of the requested independent engineering assessment and what NRC finally gave us, which was the engineering team inspection, and I will persist in that until I convince you gentlemen to reject the notion that these two are somehow equal.
Finally, just a couple of quick points.
A number of the presentations that were given, there was an admission or it could be easily derived that safety margins, while they may not have been or may not be eroded beyond what regulation provides for, are nonetheless eroded, diminished, and where this is a matter of public concern, it is truly disconcerting to see all of those diminutions at almost every turn and NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHOOE ISLAND AVE., N.W.
(202) 2364433 WASHINGTON, D.C. M005-5101 www.nealrgross.eom
317 facet atack up.
In terms of a trend, you would have to say, as far as a safety trend, it is a negative trend that has been incorporated in this application.
karlier today one of the NRC presenters referenced the off-site dose calculation manual and referred to the numbers for fenceline dose as a result of the shortened time of passage for N-16 through the loop and resulting shine in fenceline dose.
And I don' t remember the exact numbers he used, but it looked to me like he was saying the base fenceline dose from which Vermont Yankee was moving was about 15 MR per year, and that after uprate, they were looking at about 18.6.
I think those were the numbers he used.
And this is an issue that we reviewed because the State of Vermont has an agreement with Vermont Yankee in which Vermont Yankee agrees to comply with state regulation of 20 MR at fenceline, 20 MR per year, and when we first looked at the proposed uprate, the numbers we got went beyond the 20 MR.
but then what happened very quickly was that at Vermont Yankee they reached back into some MZC guidance which permitted them to adjust the calculated dose at fenceline, and what it is is a quality factor NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234-4433 WASHINGTON, D.C. 20WX701 www.nealrgross.cun
which they now applied on the difference between skin I
dose and air dose or between -- turn that around --
I between air dose and skin dose, between rads and rems.
And whereas this has been traditionally treated as a one-one equivalency, there's now in place a.71 quality factor. So I ' m not arguing with the numbers they gave you, but if it's 18.6, they arrived at that by applying for and taking credit for and using this.71 quality factor.
To the citizen walking by, what that looks like is a 29 percent discount in order to' facilitate uprate.
What wasn't mentioned is that we're now looking at the deployment of dry. cask storageland whatever little incremental dose can be expected from that will, of course, be added. That is now a matter of some contention.
The same thing is
' true, o f course, in terms of the alternate source term and control room habitability issues. NRC offered its licensees the option certain source
' term credits years ago and Vermont Yankee never saw the need until they got ready to apply for extended power uprate, and then suddenly that long list of credits that was hung on the screen here when NRC staff did their presentation NEAL R. GROSS COURT REPORTERS AND tWINSCRlBERS 1323 RHODE I U
D AVE., N.W.
(202) 234-4433 WASHINOTON, D.C. 20005-3701 www.nealr~r0ss.m
319 And 60 it essentially is a 40 percent discount of what would have been dose at the control room under accident conditions, and in order to facilitate uprate.
These are but two examples out of many that are available, and we'll write you until you really won1 t want to open the envelopes, but these are two examples out of the many that are available of the way that the safety margins have been eliminated.
And you know, we spoke in Brattleboro at least to some small degree about the removal of the old things that we used to rely on for redundancy, of defense in depth, of the individual integrity of individual safety systems. So, you know, we'll be bringing those to you, and I do thank you.
I have a couple of quotes for you. I love these little quotes. EPA Chairman Ruckleshouse once said about risk assessment, and it could be as well applied to the PRAs, that it was like capturing an enemy combattant, and if you tortured him long enough, you'd get him to say anything.
You know, we see that over and over. At my hotel room this morning, I lingered over a Christa McAuliff tribute, and that was the 1986 disaster. You know, PRA just didn't hack it there, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
(202) 234433 WASHINQTON, D.C. 200064701 www.nealrglws.com
and PRA I don't think would have predicted that since we began extended power uprate modifications at Vermont Yankee, we have had two generator trips and two scrams, and we have had reverberations throughout the system, recirc pump trips, various trips during one of those.
So bringing you those concerns.
Any questions, gentlemen?
CHAIRMAN DENNING: Thank you very much.
MR. SHADIS: Thank you.
CHAIRMAN DENNING:
We appreciate your input.
Okay. I would like to thank all of the contributors. I think that this has been an excellent meeting. I'd like to particularly thank Entergy for excellent presentations, their willingness to make modifications in their presentations, the staff also for excellent presentations. I thank the public for..
their comments.
And with that, I think we will adjourn.
(Whereupon, at 4:59 p.m., the meeting was concluded. )
NEAL R. GROSS COURT REPORTERS AND TFUNSCRIBERS 1323 RHOOE ISLAND AVE., N.W.
(202) 234-4433 WASHINQTON, D.C. 20006-3701 www.nealrgross.com
ACRS Subcommittee on Thermal-Hydraulics November 16,2005 Comments on the Vermont Yankee Proposal for the Extended Power Uprate Dr. Joe Hopenfeld On Behalf of New England Coalition
PRINCIPAL AREAS OF CONCERN Steam Dryer Failure Lack of Adequate NPSH Margins Flow Accelerated Corrosion Iodine Release
Steam Dryer Vibrations Theoretical Predictions Predictions of fatigue failure of the dryer are based on two computer models: the Computaitional Fluid Dynamics
. -. model (CFD), and-the '
Acoustic Circuit.Model, (ACM).
either
.. the CFD nor the ACM were benchmarked against full scale tests.
The flow field in the dryer is complicated by its complex geornet.
And the thermal expansion of the d er during transients may a ect X
1 the natural frequenc of the dryer. T ese are only two examples of why a validation oft I! e models under steady state and transient conditions is required.
+.
r.?.
The ascension to power tests do not validate'the CFD nor the ACM.
The'ascension to power test do not represent the loads that the dryer would experience during transients such as Main Steam Line Break (MSLB), for example.
In conclusion, the uncertainties in the CFD and the ACM reduce the reliability of converting plant data into dyer loads.
Steam Dryer Vibrations Dryer Failure Recently discovered cracks in the VY dryer indicate that stresses in the dryer may be exceeding design levels.
The growth of such cracks from flow induced vibrations during steady state operations or from dynamic loads during coolant depressurization will cause an accelerated crack growth and possible steam dryer fragmentation.
Based on the experience at Quad Cities, dryer fragments may migrate to the steam line and fragments may be shed down on to the fuel.
STEAM DRYER VIBRATIONS Safety Consequences The Quad Cities dryer failures should be viewed as precursors of similar incidents at W underXthe'EPU.
The Quad Cities incidents should also be viewed as a "near misses" of fuel channel blockage or MSlV blockage durina LOCA events; VY should be required to analyze the above worst case scenarios in a manner that provide adequate assurance that the EPU will not increase the core damage frequency beyond the present level.
Assumptions per 10CFR50.92 criteria should be presented and defended.
Steam Dryer Vibrations Lessons Learned After the Steam Dryer failures at Quad Cities, the Industry attributed the event to:
cc the lack of industry knowledge of flow-induced vibrations dryer failures" This assessment, it appears, still applies to the VY methodology.
Steam Dryer Vibrations It has yet to be-demonstrated, per 10CFR50.92, that the proposed EPU will not -
- 1.
lnvilve a significant increase in the probability or consequences of an accident previously evaluated..
I
... \\
-,-,,. 1 !
I
- 2. Create the possibility of a new and diff6rii"t' kind of accident from any accident previously evaluated.
- 3.
Involve a significant reduction in a margin of safety.
Lack of Adequate NPSH Margins Pressure drop across inlet pump screen is a major uncertainty Increase in coolant sludge concentration and other debris increases the potential for screen blockage.
In one part of their analysis W indicated that the EPU will increase sludge content. In another part of the analysis W indicated that the EPU has no effect on the debris source term.
The VY analysis with respect to NPSH margins is not conservative.
Flow Accelerated Corrosion, FAC VY analysis of wallthinning is based on a computer model, CHEKWORKS CHEKWORKS can only be used to rank domponents with respect to their susceptibility to FAC but not as a predictive tool of actual material loss.
Many failures have occurred from FAC since CMEKWORKS~W~S
- developed.in -1 986.(La-
.. r: t Salle, I --?I,:...-
I
&q-u:oyah, A N O - ~, ' ' S ~ ~ ~ ~, ~ ~ ~ ~ ~ ' ; '
Mihama) 4
(.
t VY's account of the effects of EPU on the wall thinning of critical components is not conservative. Material loss is assumed by W to be proportional to the velocity. It is more likely to be proportional to velocity squared.
Iodine Release Because of higher feed water flow rates at EPU conditions the initial iodine concentration of the coolant will decrease.
Empirical data indicates that the iodine spike increases with the decrease in iodine concentration.
W did pot evaluate the re accident iodine spike in terms of the actual I!
iodine concentration in t e coolant at EPU conditions.
The empirical concentration of the 4uCiIg used by W may not be applicable to the EPU.
VY did not discuss why the effect of the concurrent iodine spike during the MSLB accident was not included in the calculations.
The ACRS, in NUREG 1750, and at the 02103104-04/04/04 meetings, concluded that the NRC is not addressing the iodine s ike ade uately. They could not conclude that the allowable dose limits (10C E R 50, 1 !
CFRIOO 10CFR50.67 and GDC 19) would be met during the MSLB accident,,
The : NRC has recently initiated work on a new generic i$)ua (GSC 197) to reslotvethe iodine spiking issue. NRC must bound the uncertainties in GSI 197 before one can be assured that VY will meet federal laws with the proposed EPU.