ML20009A732
| ML20009A732 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 06/24/1981 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| Shared Package | |
| ML20009A733 | List: |
| References | |
| REF-10CFR9.7 NUDOCS 8107140034 | |
| Download: ML20009A732 (51) | |
Text
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NU m M RZw d TOR'l CO2e(~SSION l
COMMISSION MEETDIG D D MF d:
PUBLIC MEETING MCGUIRE APPLICATION FOR AN OPERATING LICEISE l
June 24, 1981 paggg:
1 - 49 c A q_:
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Washington, D.
C.
i ALDR%X REPORT 1XG f.
400 71-p -+a Ave., 5.W. Wash +
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D.
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20024 Talaphc=a: (202) 554-2245 8107140034 810624 PDR ADOCK 05000369 T
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1 1
UNITED STATES OF AMERICA 2
NUCLEAR REGULATORY COMMISSION 3
4 McGUIRE 5
6 PUBLIC MIETING 7
8 Nuclear Regulatory Commission Room 1130 9
1717 H Street, N.W.
Washington, D.C.
10 Wednesday, June 24, 1981 11 The Commission met, pursuant to notice, at 12 2410 p.m.
13 BEFORE 14 JOSEPH M.
HENDRIE, Chairman of the Commission 15 VICTOR GILINSKY, Commissioner PETER A.
BRADFORD, Commissioner 16 ALSO PRESENT:
17 S. CHILK 18 L.
BICKWIT J. SCINTO 19 R. MATTSON D.
RATHBUN 20 J. J '.;;c ;;; glLH oa N M. MALSCH 21 E. KEICHEN C.
TINKLER 22 J.
RILEY, Carolina En vironmen tal Study Group M.
McGARRY, Duke Power Company 23 2.
RASIN, Duke Power Company W.
PORTER, Duke Power Company 24 25 ALOERSCN AEPCAT;NG CCMP ANY, tNC, 400 V!PGINIA AVE., S.W.. WASHINGTON, O C. 20C24 (202) 554 2345
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E11CEE1E111 2
CHAIRMAN HENDRIE.
The meeting will come to order.
3 The first item of business this afternoon is tha t 4 I will ask my colleagues to join me in voting to hold this 5 aeeting on the McGuire application f or an operating license 6 on less than one week's notice.
This. is a vo te which is 7 required by the Sunshine Act and the Commission's 8 regulations on the Act.
l 9
Those in f avor say aye?
10 COMMISSIONER GIIINSKYs Aye.
11 COMMISSIONER 3RADFORDs Aye.
12 CHAIRMAN HENDRII:
Afe.
13
'J e are then legally in session.
14 This meeting has been called at Commissioner 15 G11.nsky 's request as part of the Commission's consideration 16 as to whether the licensing board's initial decision 17 authorizing full powe., full term licenses for McGuire Units 18 1 and 2 sitould become effective.
The focussof the meeting 19 will be on specific questions which along with notice of 20 t o d a y 's meeting were yesterday f o rwa rd ed to the parties by l
l 21 the General Counsel.
t 22 I am also advised tha t S taf f and Intervenor, the 23 0arolina Environmental Study Group, were advised of the 24 meeting and questions by telephone Monday evening and the 25 Applicant vis so advised by tele;; hone Tuesday m o rni ng.
I ALDERSCN AEPCRTING CCMPANY. INC, 400 VIRGINIA AVE.. S.W. W ASHINGTON. 0.C. 20024 (202) 554 2345
l 3
1nevertheless give to the assorted parties our apologies for 2 the rather short notice.
3
-The prorseding vill be as informal as possible.
4 We plan to ask the Applicant, the Duke Power Company, to 5 first resos_
to the questions, then the NRC staff and then 6 the intervening party.
All vill be subject to questioning 7 by the Consissionars.
There will be an opportunity for 8 brief rebuttals by each party and r_qain, the Commissioners 9 may wish to ask questions.
10 I should note that since the parties have been i
i 11 asked to respond to two definite questions, I will ask my 12 colleagues of the parties to stick to the subjects in hand.
13 Ihe Commission plans to consider the information 14 presented today together with the written comments that have 15 been filed by Applicant and Intervenor in its effectiveness 16 determination under Section 2.76u of the Rules of Practice.
17 Ihs t is the Appendix B to Part 2 of the Procedures.
18 The information will not be considered for any 19 o th er purpose.
In particular, it will not be considered as 20 p a r t of the eviden tiary record supporting a decision on the 21 merits of contested issues.
".so the Commission is aware 22 tha t the Circlina Environmental Study Group has moved the 23 A ppeal Board for a stay.
Any Commission decision on 24 ef f ectiveness will be entirely without prejudice to that 25 motion.
ALCERSON AEPORTING COMPANY. INC.
400 VIAGINIA AVE., S.W., WASHINGICN. 3.C. 20024 (202) 554-2345
n 1
Nov let me ask the parties, starting with Duke 2 Power, then the staff and then the Carolina Environmental 3"tudy Group, vno they intend to have as speakers today.
W4 in move foCVard.
4 5
Duke?
8 MR. McGARRYs I am Michael McGarry representing 7 Duke Power Company.
I am an attorney.
Also representing 8 Duke Power Company is Mr. William Porter who is seated a t my 9 right.
On behalf of Duke Power Company Mr. William Rasin 10 who testified in the proceedings will present Duke's 11 response to the specific two questions asked by the 12 Commission.
13 CHAIRMAN HENDRIE4 Who _ vill speak f or the staff?
14 MR. SCINTO Mr. Chairman, I am Joe Scinto with 15 the Office of Executive Legal Director and have participated 16 in this case as counsel for the staff.
In response to the 17 two technd:al questions posed by the Commission to the 18 sta ff, speaking for the sta ff will be Dr. Roger Mattson, the 19 director of the division of systems integration.
20 CHAIRMAN HENDRIE:
And for Carolina Environmental 21 Study Group?
22 MR. RILEY:
My name is Jesse Riley.
I will be 23 speaking for it.
24 CHAIRMAN HENDRIE Refere we get started, just let i
25 me note for the benefit of all parties that we have ALOERSCN AEPCRT;NG COMP ANY. INC.
j 400 VIRGINlA AVE., S.W., W ASHINGTON. o C. 20024 (202) 554 2345
5 1 scheduled this meeting for an hour and a half.
It seems to 2 me ample for the purpose.
I will ask the parties to be 3 brief and to the point in their comments so that we can get 4 through this af ternoon.
I may remind anyone who in my view 5 tends to run on too long and gets off the point.
6 Now the questions in hand are as follow.
The 7 first question is:
In view of the fact that substantial 8 quantities of hydrogen were evolved during the TF.I accident 9 bef ore containment pressure significantly exceedeu 3 pounds 10 per square inch gauge, what is the basis for selecting the 3 11 pounds per square inch gs ne containment pressure signal as 12 the appropriate trigge
~
the igniter system?
.or energizing 13 Sho uld the t.iqqer in ead be safety injection?
14 The second question is as followss In view of U.=
15 f a r t that the effectiveness of the hydrogen control system 16 depends in part on operation of air return fans and the 17 hydrogen skimmer f ans in conjunction with the igniters, is 18 i t reasonable to switch on the igniters at a lower pressure 19 than the trigger set point for the air return fans and the 20 hydrogen skimmer f ans?
Is it faasible to switch on the air 21 return f ans and hydrogen skimmer f ans at containment 22 pressures less than 3 pounds per square inch pauge without 23 the possibility of negative containment pressure or other 24 adverse f actors?
25 So Mr. Rasin, please go ahead.
1 ALOERSON RE?CRTING COMP ANY, INC.
400 VIRGINI A AVE.. S.W, WASHINGTCN. o C. 20024 (202? $$4 2345
6 1
MR. RASIN4 You have posed these two questions 2 premised on the fact that substantial quantities of hydrogen 3 were evolved during the TMI accident before containment 4 pressure significantly exceeded 3 psig.
The following 5 responses to these questions are based upon the record in 6 the reopened procaeding.
7 At the outset it shculd be noted that any 8 comparison between the hydrogen genera tion even t which 9 occurred at TMI and a similar event postulated to occur at 10 McGuire must consider the differences between the two plants.
11 The McGuire containment is an integrated system 12 which includes separate compartments, the ice condenser, the 13 air return fans, the containment sprays and other 14 equipmen t.
The operation of this integrated system must be 15 considered when analyring a postulated hydrogen generated 16 event at McGuire.
The opera. tion of this integrated system 17 was considered in our analysis of a TMI-type event occurring 18 a t McGuire.
19 In the first question you asked, what is the basis 20 f or selecting the 3 psig co n tain men t pressure as the 21 app ropriate triqq : for energiring the igniter system, the 22 basis for the 3 psic containP.ent pressure signal as an 23 appropriate trigger for energiring the igniter system is the 24 analysis that has been conducted regarding the uccurrence of 25 a IMI-type event at McGuire.
This analysis shows that a ALOEASCN REPCATING COMPANY, :NC,
4 -
7 1 containment pressure of 3 psig is reached at approximately 9
-2 90 seconds from accident initia tion.
Tnis analysis also 3 shows that hydrogen production from a zirconium water 4 reaction does not begin until about 60 minu tes into the 5 accident sequence.
6 In Question 1 yau also asked should the trigger 7 instead be saf ety injection.
We considered the safety 8 injection signal as the initiator fer energiring the 9 igniters but rejected this initia to r as being unnecessarily 10 stringent and more likely to require unwarranted igniter 11 opera tion.
We do not consider a safety injection signal 12 alone to indicate a transient with potential hydrogen 13 production.
14 Many system transients may lead to a safety 15 injection signal even though reactor coolant system 16 integrity is maintained.
An overcooling transient is one 17 example of a situation where a safety injection signal is 18 received without the loss of coolant inventory which could 19 lead to h'Idrogen generation.
20 The 3 psig containment pressure signal indicates a 21 transient involvia; loss of mass and energy from th e re a c t o r 22 coolant system.
This situation is therefore indicative of a 23 transien t with the poten ial, howeve r s -ll, for hydrogen 24 production.
25 In Question 2 you asked:
is it reasonable to ALOERSON REPCATING CCMP ANY. !NC.
400 VIAGINIA AVE. $ W. WASHINGTCN. O C. 200:4 (202) $54 234$
8 1 switch on the igniter at a lower pressure than the triqqer 2 set point for the air return fans and the hydrogen skimmer 3 f ans.
As shown in the answer to the previous question, a 4 con tainment pressure of 3 psig is reached well before the 5 onset of hydrogen generation.
Upon receipt of a con tainmen t 6 pressure of 3 psig, a sequance is started that energizes the 7 containment sprays, the air return fais and the hydrogen a skimmer f ans.
This equipment will therefore be in operation 9 well prior to hydrogen generation whether the igniters are 10 energized before or af ter reaching the 3 psig containment 11 pressure.
12 In Cuestion 2 you also asks is it feasible to 13 switch on the air return f ans and the hydrogen skimmer fans 14 a t containnent prassure less than 3 psig wi th o u t the 15 possibility of negative containment pressure or other 16 adverse f actors.
It is undesirable to energire the air 17 return f ans and skimmer f ans at a containment pressure less 18 than 3 psig f7c the following reasons.
19 No.
1, this would result in a red uction of the 20 actua tion sot points and would require a major reanalysis of 21 the design basis accidents for the McGuire plan, The 22 engineered saf eguards features of the containment are 23 designed to mitigate the effects of a loss of coolant 24 irrident, among others.
25 The set points and timing sequences of equipment ALCEASCN AEPCATING CCMP ANY. !NC, 400 VIRGINI A AVE., S.W. 'NASHINGTCN, O C, 20024 (2021 554 2345
9 1 operation are significant f actors in the de sign basis 2 accident analysis.
These design basis analyses have been 3 performed in accordance with Commission, regulations and are 4 contained in the McGuire FSAR.
They have been reviewed by 5 the NEC, and previous licensing actions have been based in 6 part on the results of these analyses.
7 do.
2, reduction of the actuation set points could a give rise to an unnecessary loss of ice.
Unnecessary 9 operation of the 11r return fans reruits in forced air flov 10 through the ice condenser and a melting of the ice.
Ice 11 inventory would be reduced which could decrease safety 12 margins if a subsequent blowdown from the reactor coolant 13 system does occur.
If reactor coolant system integrity is 14 m aintained, replacing the lost ice would ha ve signif icant 15 iznact on returning the plant to operation.
.16 No.
3, redurtion in the actuation set' points could 17 give rise to a reduction in ECCS vater inventory and to 18 substantial unnecassary cleanup a c ti vi tie s.
The ea rly 19 operat' on of the contain.9ent spray system would be 20 und esirable.
Energizing the sprays without significant 21 blowdown f rom the reactor roolant system would serve no 22 purpose and would reduce the water inventory in the 23refu'aling water sto rage tank.
This inventory reduction 24 would require earlier switchover of ECCS on the 25 recirculation mode if subsequent blowdown were to occur.
ALOEASON AEPCRflNG COMP ANY, INC.
400 VIRGINI A AVE., S.W4 WASHINGTCN. O C. 20024 1202) 554 2345
90 1
If reactor coolant system integrity is maintained, 2 the containment and equipment would have needlessly been 3 subjected to slightly radioactive chemical sprays.
The 4 plant recovery would be significantly delayed while the 5 containment was being cleaned and decontamina ted.
6 I would also note that it would be unreasonable tr 7 require reduction in the actuation set points because it 8 vould not improve the effec:iveness of the mitigation 9 system.
As previously discussed, the loss of mass and to energy from the rasctor coolant system vill result in a 3 11 psig containsent pressure before hydrogen production begins.
12 Containment pressures less than 3 psig do not 13 necessarily indicate that a LOCA has occurred.
On the other 14 hand energizinc. the air return fans with no mass and energy 151oss from the raa: tor coolant sy tem vill result in cooling
'6 the containment atmosphere and reducing containment 17 pressure.
When containment pressure is reduced to.25 psig, 18 the air return fans, hydrogen skimmer fans and containment 19 sprays are automatically tripped off.
20 These systems vould then have to be manually 21 restarted when containment pressure again exceeded.25 psig 22 or W Juld automatically start when containment pressure 23 reached 3 psig.
Io assure continued operations of these
~
24 s ystems a t lover set points, the.25 psig trip would have to 25 be removed.
If this trip point were removed, the potential i
i ALOERSCN AEPoRTING COMP ANY. INC.
400 VIRGINIA AVE., S.W., WASHINGTCN. o C. 20024 (202) $54 2345
1 17 1 for the creation of a vacuum inside containment is d
2 significantly incres sad.
3 I hope that.is responsive to the questions that 4you posed to us.
I would be happy to discuss my response in 5 note detail.
4 6
COMMISSIONER GIIINSKY Can I say a wcrd here?
7 Let me say something about what lies in my mind 1
8 behind Ouestion 1.
It is.true, as you say, IMI is i l
9 dif ferent reactor.
It is larger and McGuire would likely 10 teach _ hicha r pressures more quickly.
At the same time 11 McGuire has ice chests which would tend to condense steam.
12 I t seems to me it is difficult to see your way through all 13 acciden t sequences.
14 So if or.e were to switch on the igniters at an 15 earlier point, for example safety injection, I would think 16 you would :spture or protect against the la rger class of 17 possibilities at what would seem to me negligible cost.
I 18 would Hb e in t erestd to know how often you wo uld expect safety 19 injection to come on during the operation cf the reactor, 20 because you have said if you did it at that point you might 21 needlessly turn on the igniters or too frequently turn on 22 the igniters.
23 At any ra te, that is what lies behind my interest 24 in Question 1.
I wonder what your view is about the 25 question of in effect protecting against a larger class of i
i ALCERSCN AEPC ATING CCMP ANY, iNC, 400 VIRGINIA AVE., S.W., WASHINGTCN. O C. 200:4 (202) 554 2345
12 1 possibilities at what seems to me to be negligible cost.
2 3R. RASIN4 I would agree with you that th e 3 significance, we attached to this particular trigger for 4 turning on the igniters is to minimize the number of times 5 the systems energized or the challenges to the system.
We 6 think that in general it is good engineering practice not to 7 use the system until you need it.
8 In terms of protecting it against a broader range 9 of accidents, to ge t into a hydrogen production mode you 10 h av e go t to lose a lot of mass and energy from the primary 11 srstem.
That energy goes into the con tainmen t.
If one were 12 to look at events which took longer to resch the 3 psig 13 sig nal, you would find that it also took much longer to go 14 f rom that point to the poin t where you had uncovered the 15 core and were in i hydrogen production mode.
16 So the length of time between when yo u energize 17 t h e igniters and when you actually had hydrogen coming out I 18 think would be increased.
19 COMMISSIONER GILINSKY:
How confident can you be 20 tha t in f act you will reach the 3 psi level before 21 generating hydrogen?
At TMI the pressure reached 4 pounds I 22 think so.tewhere along the way bef ore it ultimately burned 23 t h e hydrogen.
But it seems to me it depends on details of 24 the accident that might easily have been lower than that.
25 MR. RASIN:
If you look at what happened, for one
~l AL.cER$oN REPORTING CCMP ANY,iNC.
400 VIRGINTA AVE., S.W. W ASHINGTCN. O.C. 20024 (202) 554 2345
i l
i 13 1 thing at TMI as soon as the operators noticed the increase 2 in containment temperatures, they anergired their 3 containment cooling systems and shifted the containment 4 cooling fans to fast speed.
Those actions are somewhat akin 5 to our ice condenser air return f an operation.
So they in 6 f act actuated their systems prior to their set points.
And 7 their set points sre much higher because of the larger 8 containment and the larger design pressire.
9 Our containment system reaches 3 psig much more 10 rapidly.
In fact if you look at the pressure that was 11 attained during the early stages of TMI, it is in the range 12 o f 2 to 2. 5 pounds very early on.
That would, if one 13 considered the entire containment volume at McGuire, be at 14 le ast double that amount in McGuire for the same amount of 15 blowdown from the system just because of the ratio of the 16 volumes.
17 COMMISSIONE3 GILINSKI:
I understanf that.
But I 18 would think it would be difficult to calculate with a lo t of 19 certainty the interaction of the steam with the ice and so 20 on down to 1 psi plus or minus 1 ;sig.
It just seems to me 21 prudence su toests to take the earlier signal as triggering 22 the igniter system.
23 I wonder on tha t point whether you could pursue 24 the question of just what is the disadvantage in doing that 25 other than the general principle of not exercising ALCERSON AEPoRTING COMPANY,;NC, 400 VIRG:NIA AVE S W. WASHINGTCN. O C. 20024 (202) 554 2345
1 14 1
i 1 protective system needlessly.
Hov often would you expect 2 saf ety injection to come on in the normal course of events?
3 MR. RASIN:
I can't really romment to you in terms 4 of number of expected transients.
I guess I would just 5tefer in ganeral to the incidents and transients that occur 6 at other reactors.
7 COMMISSIONER GILINSKY How f requently would you 8say they occur per reactor?
9 MR. HASIN:
I would say over the country per 10 reactor it may be at least half a dozen transients per year 11 through tha country tha t I see with initiation of ECCS for 12 one reason or another.
13 COMMISSIONER GILINSKY4 I would think the number 14 would be la rger than tha t, about or the order of once per 15 yea r per reactor or less than that at any rate.
It does not 16 seem to me that that would be very deigeroer to turn on 171 gn i t e r s.
18 MR. BASIN:
No, sir.
I do not mean to imply at 19 all tha t it is dangerous.
I say our only reason is what we 20 f eel is good engineering judgment in not using the system 21 until it is required.
~4i th this type of equipment, if I 22 v ec e to expect to have an effect on the equipment I would 23 expect to have it when I energire the equipment, much like a 24 lig h t bulb.
It bu rns out when you turn it on, not when it 25 is sitting there burning.
It is on that basis solely.
ALDERSoN REPORTING COMP ANY, INC.
l 400 VIRGINIA AVE.. SJW. WASHINGTCN 0.C. 20024 (2021554 2345
15 1
COMMISSION ER GILINSKY :
I guess what I find 2 unconvincing is tha t there are not events which should be 3 protected against or sequences which are no t captured in the 4 procedures tha t you have recommended.
It seems to me that 5 at negligible cost one could achieve greater assurance enat 6 in f act those are protected against.
I find it hard to see 7 the objection to doing that.
8 MR. RASIN:
I would not have an objection to doing 9 tha t.
10 COMMISSIONER GILINSKY:
I mean if there is a good 11 obj ection, I would like to knov it.
I would not like to 12 force things in a direction that does not make any sense.
13 That is what I am trying to get at.
14 MR. R ASIN :
Ihe objection that we have right now, 15 and it is not really an objection.
We are just sta ting to 16 you our basis f or choosing this set point.
As ! said, we 17 considered saf ety injection, conside red Pha se 3 isolation.
18 We considered them from the standpoint of operation of a 19 sys tem to be equivalent, no difference from the standpoint 20 of the way the system would work, because ve still feel we 21 vill ha ve the igniters.
We vill have the sprays.
We vill 22 ha ve the air return fans, the hydrogen skimmer fans a2'_ in 23 operation before ve get hydrogen.
24 CHAIRMAN HENDRIE.
Peter, do you have anything?
25 COMMISSIONER 3RADFORD:
No, sir.
AL0EASoN AEPoATING COMP ANY. :NC.
400 VIRGINI A AVE., S.W., WASHINGTON. o.C. 20024 (202) $54 2345
i 16
.-1 CHAIREAN HENDRIE4 Roger?
2 dR. MATTSON:
I hae a prepared response to each of 3 the questions.
But before I get into the f ormality of 4 reading it I would like to make two general observations 5from the tone of the questions and the ay I think we are 6 headed.
7 First of all I would like to point out there may 8 be a slight mistake in your understanding concerning th e 3 9 psi at THI 2.
It is our understanding based on the reading 10 of probably th e best analysis of the accident th a t has been 11 done, that by NSAC, that the containment started at minus 2 12 p si.
That is something that is not allowed for McGuire or 13 the -ice condenser plants that was allowed for TMI 2.
That 14 mea ns that the differential pressure at TMI 2 had reached 15 4.8 psi at a half hour into the accident, well before la rge 16 amounts of hydrogen were generated.
17 Now you have said, and you are correct, that it is 18 very dif ficult to make a direct comparison between the 3 psi 19 or the 4.8 psi or any psi at TM! 2 and the corresponding 20 number in in ice rondenser plant.
The sires are different.
21 The effect of the ice in suppressing, the pressure of ice 22 h a s to be accountad for.
And so the approach we have 23 chosen, you will see that in my prepared answer, is to use 24 analyses specific to the pa rticular ice condenser plants to 25 arrive at a decision that the initiation scheme that they I
i ALCERSoN REPORTING COMP ANY, INC, l
400 VIAGINIA AVE.. S.W. W ASHINGTCN, D.C. CO24 (202) 554 2345
17
.1 p roposed is adequ a t e.
2 The second thing I would point out, before the 3 prepared remarks is that, as you are aware in the Sequoyah 4 case, we have called our approval of the distributive 5 ignition system an interim approval.
We have told you 6 bef ore of the things that we consider that need to be done 7 bef ore final approval of these ignition systems by January a 31 of 1982.
One of the things that we will continue to 9 consider and had planned to con tinue to consider is the 10 initiation schese f or the igniters.
11 C05.1ISSIONER GILINSKY At Sequoyah I believe it 121s the safety injection that is the triggering signal.
13 3R. MATTSON:
That is the way it has been 14 described.
That unfortunately is a bit of a shorthand 15 description for the initiation scheme.
It is actually a 1611ttle bit diffarant than that implies.
The procedures at 17 Sequoyah call for turning on the igniters f or every trip of 18 th e reactot.
What they say is after the opera tor has 19 con firmed that the equipment required to automatically 20 respond to a trip is operable, then before entering any 21 emergency procedure for diagnosis and response to an
-22 acciden t, the opera tor dispa tches a person to the igniter 23 panel to turn on the igniters.
24 So that would be more often than every safety 25 injection signal.
ALDERSON AEPCATING COMPANY, :NC.
400 VIRGINIA AVE., S W. WASHINGTON. 0.C 200:4 (202) 554 2345
18 1
I was just checking with the staff a minute ago.
2 It is our recollection that the number cf trips per year 3 ranges f rot these to ten in the United States per reactor, 4 depending on the design, and that approximately half of 5 those might be expected to result in a gafety injection 6 signal.
7 Ihe point I was trying to make, the second point 8 is that con s is t e n t with our raquiring a number of additional 9 things to be done beyond the in terim approval of the 10 d'istributive ignition system, some of the details that you 11 have heard today from Duke we have not heard before.
Some 12 o f the pa rticular reasons f or choosing 3 psi rather than 13 some other initiation signal, consistent with our requiring 14 them to look into that further, some of the information tha t 15 is presented here has not been presented to us for review 16 prior to today.
17 Let me also say that our position is not a hard 18 one on when the ignition systam should be initiated.
It 19 could not be.
We have approved two initiation schemes, one 20 f o r Sequoysh and a different one for McGuire.
21 If I could then, 10t me read the prepared remarks.
22 Ihe McGuire emergency hydrogen mitiga tion system 23 as reviewed and approved for interim operation is manually 24 actuated out, the main control room upon receipt of an 25 automatically taitiated Phase 3 isolation signal.
Ihe Phase l
ALOEASON 4EPoAflNG COMP ANY. iNC, 400 VIRGINIA AVE S.W.. WASHINGTON. O C. 200:4 202) 554 2345
19 l
13 isolation signal is produced upon reaching a high, high
)
2 containment pressure signal of 2.9 psig.
Duke has chosen 3 the Phase 3 isolation signal on the basis that the signal 4 vill provide an early indication of accidents which have the 5 potential for excessive hydrogen generation.
p 6
Furthermore, the selection of a Phase 3 isolation 7 signal which in turn is derived from high, high containment a cressure as the actuation criterien increases assurance that 9 accompan ying safety systems, that is the sprays and fans, 10 vill be operating.
11 The staff previously has reviewed this issue and 12 conclud ad that for the interim period until January 31, 1982 13 the actuation criterion sele-ted by the Applicant is 14 acceptable.
This was based on a preliminary judgmert that a 15 containment pressure set point of 2.9 psig is sufficiently 16lov to anticipate hydrogen generation for the 32D accident 17 scenario which was used as a basis for the staff's interim 18 a pp roval.
19 In tha t scenario the 2.9 psig pressure set point 20 is exceeded in approximately 200 seconds.
The containment 21 pressure analysis indicated that th e peak containment 22 pressure prior to hydrogen generation occurs at 23 app roximately 800 seconds at a value of about 7.5 psig.
At 24 this time operation of safety systems, that is fans and 25 sprays, acts to decrease the pressure.
By contrast, the i
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20 1 inalysis also indicates tha t the onset of h ydrogen 2 generation is at approximately 3500 seconds.
3 While the pressure analysis was noc performed to 4 produca tha minimum expectad pressure rise which would 5 increase the time period to reach the set point, this time 6 interval appears to be more than adequa te since manual 7 actuation of the igniters outside the control room should 8 take no more than several minuter 9
While we maintain that the system approved for 10 McGuire is adequa te, we intend to continue our review of the 11 operational aspects of igniter systems including actuation 12 modes and set points prior to final approval.
-13 Fcr your second question, actuation of the 14 igniters at a lower set point or earlier on time poses no 15 problem in our judgment so long as the systems are 16 f unctioning when needed.
Reiterating our position, the 17 staf f believes that actuation of the igniters on Phase 3 18 isolation or earlier, as is the case for Sequoyah, is 19 acceptable f or interim approval.
20 The sprays and fans for Sequoyah and McGuire are 21 actuated on a high, high rontainment pressure set point 22 which we believe will be reached prior to excessive h yd rog e n 23 ;eneration.
Thus actuation of the igniters at an ea rlier 24 period should be inconsequential.
In any event, even if 25 hyf rogen were relaased with only the igniters operating, a ALDERSON AEPoATING COMP ANY, INC.
4@ %1 A$1NI A.AV@, $ W., WA@HINGTCdN, 0 Q. $@$4 ($@) $@4 $4@
21 1 lik ely result would be that a small quantity of hydrogen 2 would burn causing suf ficien t pressu re rise to reach the set 3 point which causes initiation of the sprays and fans.
4 Regarding the second point of the question, we see 5 no obvious reason why the fans could not be initiated on a 6 lower pressure.
This would however increase the probability 7 of inadvertent o pe ra tio n.
8 CHAIRMAN HENDRIE:
Do you have any questions?
9 COMMISSIONER GILINSKY:
No.
10 CHAIRMAN HENDRIE:
Mr. Riley?
11 MR. RILEY:
Thank you.
12 I will distribute some copies of material bearing 13 on this point.
The first one of these, if I may distribute 14 to the Comsissioners and to Matt and the parties, is the 15 hydrogen appendix to the Nuclear Safety Analysis Study that 16 w a s ref erred to previously.
I have circled in red the 17 initiation of the acciden t, p re ssu re builde rs during the 18 acciden t.
This may be an inaccurate chart, but it indicates 19 tha t the initial pressure was less than one pound, on the 20 order of five-tenths of a pound.
It indicates that 3 psi 21 was not reached until focr hours out.
22 Now I agree with.the statements by Mr. Easin and 23 M r. Mattson, but for the scenario that has been assumed for 24 McGuire there wo uld be a ve ry rapid pressure rise and 3 psi 25 would t e exceeded in a matter of minutes.
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l
~
22 l
t The thing that went wrong, so to speak, at TMI in 2 terms of our using it as an example in this case were 3 several means of mitigation.
3r. Rasin has referred to the 4 opet ation of tha 11: cooling system.
If you will take a 5 look at the second sheet in the handout, you will see a 6 figure f rom NUREG-600 which is the staff's analysis of the 7 ?!I accident.
Encircled in red you will see that during the 8first four hours that make-up Pump A was operating.
It was 9 thrott'.ed at some point but it was operating.
You will also 10 see that before four hours was reached there were four or 11 five instances of high pressure coolant injection.
12 All of these things would result in cooling of the 13 con tent of the reactor coolant system.
It would reduce the 14 amount of energy of the liquid that was escaping and the 15 steam that was escaping from the pressurirer.
I feel that 16 these unanticipated factors were responsible for this ra the r 17 slow build-up of pressure in the containment, that and 18 something that we had not mentioned.
That is that the 19 con tainment itself and all the equipment had acted as a huge 20 condense r.
21 Obtained by discovery on the staff, the 22 temperature record of the atmosphere at TMI never exceeded, 23 as I recali, 170 degrees Fahrenheit, which means tha t during 24 all that period it was able to act as a condenser and 25 suppress the pressure contribution of water vaper.
l ALOERSCN AEPCATING COMP ANY,.NC, 400 VIAGINlA AVE., S W,'NASHINGICN. O.C. 20C24 (202) $54-2345 __
23 1
I as a bit concerned about the statement in 2 Question 1 initially that hydrogen was present when 3 psi 3 was reached.
I would like to know if the staff's evidence 4was based on an interpretation of the rurve in the first 5 figure which shows that rough rise is a little after three 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and a little before four hours, because the first 7 analysis of the content of the atmosphere was made on March 8 30 af ter tne burn had taken place.
9 As far as I can tell -- I have not gone over the to reactimeter of chart content there was no hydrogen 11 monitor in the plant.
I an intere-ed in the evidence that 12 there was hydrogen present before 3 psi was reached.
13 With respect to the McGuire situation, I feel that 14 the materiality of whether the igniter system activation is 15 a t the present signal or it an earlier signal rela tes to how 16 well any accident there follows the assume scenario which is 17 an S20 accident which is not identical to the Three Mile 18 Island accident.
The Three Mile Island accident probably 19 occurred at a slower rate because the FORY leaking through 20 the long length of pipe ronveying it down to the pressurizer 21 :elief tank esuld be slower than a two-inch pipe that was 22 sim ply b roken a t a ' p oi.' t near a larger line in the reactor 23 s ys tem.
24 If we permit ourselves to depart then from the one 25 sta nario that was considered by the Applicant and the swaff AL::ERSON AEPC ATING COMP ANY. ;NC.
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24 1 in the proceeding, it would seem to me because of these 2 unantiripa ted a evia tions f rom that particular script that 3 would be a step of conservatism to initiate early.
I would 4 feel that an injection signal vould be one of the earliest 5 signals for such initiation and that vould be in the 6 interest of conserva tism to do so.
7 I agree with 3r. Basin tha t it would cause some a clean-ups and some loss of generating time.
But the value 9 in terms of prudence, particularly since we are dealing with 10 a thin-shell containment, I feel would be worth it.
11 I want to note i_ passing, the poin t was already 12 m ad e, that the volume of Three Mile Island is not quite 13 twice that of McGuire.
cGuire corrected for ice is 141.13 million cubic f ee t.
T5I is 2.05 million cubic f,et.
15 That certainly does nean that the pressure rise signal which to ve see in this first sheet of the handout would be about 17 half wha t you would expect in McGuire, providing that the 18 scenatin is follows.
19 Nov vith respect to Question 2, the air fans are 20 not designed to start until ten minutes after pressure 21 dif f eren tial 3,000 has been reached.
And as the first 22 hydrogen release occurs at pressure drop of 19.3 pounds 23 absolute which is u.6 pour f s gauge, it would seem that the 24 3 pounds, again assuming we are folloviaq the script, would 25 be early enough, again where scenario depended.
ALOERSoN REPORT lNG COMPANY, INC, 400 VIRGINIA AVE., S.W.. WASHINGTON. 0.C. 200:4 CO2) $54+2345 1
25 1
Despite I am sure the effort that was made to 2 train its opera tors to follow certain procedures, as there 3 is a possibility of attempts at mitigation of pressure 4 increase, I feel that early activation of ignitors vocid be 5 essentially harmless.
6 With respect to vacuum effects, the containment I 7 f eel would be well equal to it.
M r. Ra sin I think correctly Spoints out that some systems would start operating with a 9 negative quarter pound being reached, and again it would be to a matter of inconvenience.
It I would'11ke to indicate, though, a source of 12 concern of turning on the igniters and not making provision 13 f or turning them off, berause I bellers that your analyses 14 in the f uture are going to show that a time vill be reached 15 in which the less haza rdous thin 7 to do is to turn off the 16 igniters and permit the recombiners to dispose of the 17 hyd rogen in the en vironment.
If it would be a pleasure of 18 the Commission I would like to iridicate why I think this is 19 the case.
20 The second part of the handout indicates some of 21 the situation.
There are seven attachments to the pipe 22 which leads to prassurizer r.elief ta nk s.
One of these is 23 spray no::le.
Tnree are power relief valves and three are 24 raf ety valves.
I have red-checked the pressures at which 25 these opera te.
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26 1
COMMISSIONER GILINSKY:
I wonder if we could 2 return to this af ter we have completed dealing with the 3 actuation question, or however you want to do it.
4 CHAIRMAN HENDRIE:
Why don 't we let them go ahead 5 and get the proposition stated.
Then I want to go around 6the table again, and people vill have a chance to comment on 7 the other parties' remarks, including this point.
8 COMMISSIONER GILINSKY :
Good enough.
9 MR. RILE!s Further information on pressuriter 10 relief tank from the FSAR is given in the following pages.
11 The next stapled portion of material is from 12 N URIG-CR-1219.
I really think that this is the heart of the 13 sat te r.
When the Commission asked a question about 14 3 percent hydrogen, I assume it meant a uniform 15 concentration throughout the containment of 3 percent.
Nov l
16 it is arguad very p e rsua sively in this NUREG report tha t the 17 hydrogen concentration at Three Mile Island was not uniform, 18 th a t the place where ignition occurred v.s a much higher 19 concentration than that on the average of the containment 20 and certainly the same heterogeneity and hydrogen 21 concentration vill be true for McGuire.
22 I really think that this is the heart of the 23 m a t ter.
Until our analyses deal with the case of a range of 24 hydrogen concentrations, I feel that we are going to come 25 out with mistaken conclusions with regard to when to turn ALOERSCN AEPCRTING COMP ANY. iNC, 400 VIRGINIA AVE S.W, 'N'ASHINGTCN. O C. 20024 (202) 554 2345
27 1 ignitors on and when to turn igniters off.
2 Now the remaining documents are from McGuire 3 FSAR.
They will anable you to visualize where the various 4 elements in the plant are.
On the first sheet you will see 5 in elevation the location of the pressurizer.
In the second 6 sheet you will see the location of pressurirer plan and of 7 the nine hatches through which return air is provided to the 8 lower compartment which contains the reacto r and where the 9 leak would presumably occur.
10 The elevation of the sheet just referred to is 11 738.
The elevation of the next one is 768.
We see where 12 the air return f ans are.
We see that the inlets for the air 13 return f ans see diametrically opposite the location of the 14 pressurizer.
If we go on to the next sheet, we see the 15 la yout of the ice condensers and we see that the air return 16 f an inlets are between the ends, the open space in the ice 17 condensers.
And when we go to the last of these legal-size 18 sheets, we see that the hatches venting the ire condenser 19 correspond to, of course the condensers themselves are 20 uniformly distributed to that section.
21 Nov 21 minutes after hydrogen release begins, it 22 will reach a maximum.
This inf ormation is for the 520 23 scenario.
You will find it in Duke Power's analysis nf 24 hyd rogen control measures in Volume 1,
and the information 25 is given in Table 2 where the hydrogen release rate, mass AI.DEASCN AEPQATING CCMP ANY. INC.
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28 i
1 release rate is given.
2 The water release rate is given in Table 1.
Some 3 simple cairulations show that at the peak of the accident i
4 the flow of steam and hydrogen into the lower compartment 5 will bs three tima s tha t of the return air, which means that 6three-quarters of the parts into the ice condenser are going 7 to receive hydrogen and steam.
Under these conditions the 8 thorough mixing of that one-fourth of air with those 9 three-fourths of steam and hydrogen is certainly not going 10 to be complete.
There is going to be a small transition 11 region where there is some mixing.
12 But what it means is tha t a ve ry substantial part 13 of the steam and hydrogen is going to go into an ice 14 condenser unaccompanied by any air.
Now th e steam vill 15 condense out.
And the air in the portions of the ice 16 condenser adjoining will la terally move toward the close-in 17 to make up for the volume of the steam.
18 What it amounts to is that there is going to be a 19 th annel of approximately 30 feet by 10 feet in the ice 20 condenser emerging at the top on the opposite side of the 21 air return f ans where you are getting up to pure hydrogen.
22 There is going to be a transition band but you are going to 23 have an extremely high concentration of hydrogen in the 24 center.
That hydrogen has about 7 perrent the density of 25 the air atmosphere.
It will be enourmously buoyant.
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29 1
As you can see from the plans, th e thing that vill 2 happen is that that hydrogen vill move to the top of the 3 dome whe re there are a group of igniters.
For a while that 4 hydrogen vill burn off because there will be enough oxygen 5 present.
In the last sheet of the handout you see the 6 turning diagram which indicates the vicinity in which 7 hydrogen burns in relation to air and steam composition and a the region in which it de tonates.
9 But after that portion of the hydregen which has 10 had suf ficient air to combust has combusted and the supply 11 becomes hydrogen which is unburnable because it lacks 12 oxygen, one vill accumulate a volume of hydrogen in the dome 13 with the igniters below and nothing happening except tho t 14 the air return fan system will still be operating, causing 15 some circulation.
There is what engineers call a flow net 16 which vill have maximum flow in the vicinity of inlets, the 17 air return f ans, and minimum flow in the region f rom which 18 t he hydrogen vill have issued.
19 But slowly there Will be mixing and there vill be 20 dif fusion.
It is very obvious, if you visualire this, that 21 t he minimum concentration of air vill be at the top in the 22 vicinity of the igniters and slowly oxygen vill rise, 23 increasingly making the mass combustible.
24 Finally there vill be a combustible composition in 25 the vicinity of an igniter with a large combustible and 4
ALDERSON REPCRTING COMP ANY, iNC, 400 VIRGINIA AVE., S.W., W ASHINGToN, O C. 20024 (202) 554 2345
30 1probably detonable volume of hydrogen below it.
That I 2 think is what Dr. Berman ?.ad in mind when he said the use of 3 the distributive icnition system under certain circumstances 4 la fraught with danger, and I believe that is the 5 circumstance.
6 For that reason I would recommend that a study be 7 nade by this Commission to determine that point where it 13 8 safer to turn off the igniter system and every other 9 electrical device in the containment except the recombiners 10 and allow the recombiners to take care of that hydrogen.
11 CHAIRMAN HENDRIE:
Thank you, Mr. Riley.
12 Depending on the inclination for questions from 13 this side of the table, I propose to switch back across the 14 p a r ties, asking for comments on one another's remarks.
You 15 pro bably have some more questions as we go along.
16 MR. McGARRY:
Could we have the Commission 's 17 indulgence f or about one minute so we can caucus, as it were?
18 CHAIRMAN HENDRIE I do not see why not.
While 19 you are caucusing maybe we can go ahead and ask the staff to 20 com ment.
21 MR. McGARRY:
I think we can be ready in about one 22 m in u t e.
If you would please hold for that one minute, we 23 would like to hear the comments.
24 CHAIRMAN HENDRIE Go ahead and raucus.
25 (Discussion was held off the record.)
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31 1
COMMISSIONER GILINSKY:
Mr. Rasin, before you 2 start, I want to say a word.
I want to say again that I 3 don 't know what the particular view is, but where the 4 hydrogen igniter system ought to be turned on, what I wanted 5 to understand was your rationale for picking the signal that 6 you have picked.
It does not seem to me however tha t trying 7 to avoid turning
.t on once or twice or even three times a 8 year, using the numbers that were given to us a few minutes 9 ago, is a sufficiantly good reason for picking the 3 psi as 10 opposed to an earlier point.
11 I assume that 12 MR. RASIN:
I guess that 13 COMMISSIONER GILINSKY:
-- the system more 14 f requently than that anyway.
You probably test it several 15 tim e s a yea r.
16 MR. RASIN:
It is I think tested at leact four 17 times a year.
It is energired for tet:ing.
18 In terms of what is a good enough reason for you 19 and what is a good enough reason for'me, I suppose there is 20 j us t a difference.
I suppose I have good enough reason to 21 believe that if you are, going to need these things, you are -
22 going to gat the 3 psi and-I am confifent that safety 23 injection and 3 psi are equivalent on a transient where you 24 are going to need these things.
25 I would admit, as I said before, that is our only 1
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O 32 1 basis.
And we scree with the staff in terms of their view 2 that both schemes are at this time scraptable from the 3 standpoint of the operation of the mitigation system.
I 4 would scree with that.
And our basis is and remains as I 5 have stated.
6 I-would like to take issue with the staff's 7 position with regard to the air return f ans.
I would not 8 agree that there is no problem with initiating the air 9 return f ans escliar than the 3 psi.
The air return fans are 10 an integral part of the con tainment and engineered safeguard 11 f ea tures.
12 The plant was designed with many bases in mind.
13 The mitigation system is put in to handle ona eent within 2 do not feel that 14 t h e whole realm of the plant o pe ra tio n.
15 the rest of the plant should have to bend to the 16 installa tion of that one pa rticular system by changing thos" 17 set points.
18 It tould require a reanalysis of the accident to 19 ascertain what
.e effect of operation of the air return 20 f an s a t a-different time would be, whether there would be 21 a n y effect, because there would essentially be none if the 22 blowdown had not yet been concluded.
And I would not put 23 tha t in the realm of wha t you would call a painless or not 24 expensive change to make.
I would consider that a very 25 significant and expensive and unwarranted change to make.
ALDEASON AEPoATING CCMP ANY. ;NC, 400 VIAGINIA AVE.. S.W. WASHINGTON O C. 20024 (202) $54 2345
33 t
L 1
CHAIRMAN HENDRIE:
Since you turn the igniters on, 2 on the basis that it had reached a certain set point, the 3 procedure, say if you reach that point, is you go and turn 4 them on and the operator then goes to the switch cear and 5 throws tha appropriate switches so it is a manual 6 procedure.
What would be required then to turn the igniters 7 on at a lower pressure or a t some other event such as the ainitiation of safety injection is just a chance in the 9 opera ting procedures --
10 MR. RASIN:
Yes, sir, th a t is correct.
11 CH AIRM AN HENCRIE:
and a not trivial point,
-12 s aking sure tha t the operating staff understands the enance 13 and some opera tors are not under the impression the old 14 rules apply and some that the new apply.
15 But ! am inclined to agree that changing the 16 sequence at which other equipmen t comes on, fans and so on, 17 is a rather more significant natter.
One really has to go 18 back then and redo all of the containment analyrrs to make 19 sure you have not done something unfortunate.
So I am 20 included to agree with that.
21 Are there other questions?
22 3R. 3ATTSON:
You asked in the question whether it 23 was feasible, and I snswered the questions yes, it is 24 f easible to lower the set poin t.
Is it necessary?
No.
Is 25 the money earranted to rado the anslysis to ma:.-
sure s11 ALOEASoN REPCATING OoMP ANY. :NC, 400 VIAGINIA ANE., S.W, WASHINGICN O C. 200:41:02) 554 2345
34 1 the other reasons that 3 psi was picked f or the f ans, is 1
2 that reanalysis warranted by the concern that is expressed l
1 3 here?
We do not believe so.
4 COMMISSIONER GILINSKYa But what about the first l
l 5 question ?
It seeas to me that by using an earlier signal to 6 initiate the igniters, protecting against a larger class of 7 possible accidents, and the disadvantages of turniac the 81gniters on once or at the most several times a ' ear, a 9 couple of times a year, seem pretty slight.
Wi f not do it 10 a t the earlier point?
11 MR. MATTSON:
We tend to agree with you.
What I 12 said in my statement was that our plan was to take a little 13 longer to look at it but our position is not hard and fast.
14 Just by way of comment to Mr. Riley's remarks, I 15 would urge you not to select prudence as the sole basis for 16 indiscrimina tely requiring further actions by control room 17 operators ind auxiliary operators in the event of reactor 18 scrams.
You vill recall how we have cautioned 7ne another 19 since TMI with loading up reactor operating s' rnd 20 reactor control rooms with more and more things y have to 21 d o o f f the top of their heads e very time the bell l ings.
So 22 prudence itself is not a reason to go turn the igniters on.
23 If the thoughtful.onsideration of ether accidents l
24 tha t might find a way to produce hydrogen without producing I
i 25 3 psi leads you to beli ve that you would significantly r
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i 35 1 enlarge the vindow of protection afforded by the igniters, 2 that is a good reason to turn them on.
That is the vindov 3 ve are exploring, and we had simply decided some months ago 4 to take tha cast of 1980 to answer that question.
5 OHAIRMAN HENDRIE:
You mean 1961.
You have 6 already ta' ten the cast of 1980.
7 MR. MATTSON:
Yes, 1981.
8 (Laughtar.)
9 MR. MATTSON:
The question that Mr. Riley raised 10 on when to turn the igniters off is not a new question and 11 also is included in the vock that we have ongoing, 12 principally generated by some of the testimony in th e 13 3cGuire hearing.
14 Suggestions have ranged broadly on how igniters 15 ought to be controlled, when they ought to be initiated, 16 sno uld they be turned off in some sttuations, even so far as 17 th e suggestion th a t individual igniters may need local 18 detection and control devices.
That could get rather 19 cumbersome and rather expensive but remains one possibility 20 th a t is in front of us as we continue to look at what ought 21 to be the required hydrogen mitigation system for the
'nq 22 term and the small containments.
03 So in addressing those kinds of questions we vill 24 have to come to grips with when on snj vhen off.
I welcome 25 the suggestion tha t we look at that question.
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36 1
In fact the record of this proceeding has on it a 2 considerable discussion of the inerting of hydrogen by steam 3 or fog.
He seems to be adding -- this is the first time I the additional parameter of 4 have heard his argument 5 accessibility of air to concentrations of hydrogen once the 6 steam goes away.
You will leave concentrated areas of 7 hydrogen and how will the air find its way to those 8 concentrations:
that is a nuance that was not on the record 9 to my knowledge.
But the question of lower plenum inerting 10 f ollowed by dry-out and steam leading to transitions to 11 detona tion and things like that you have heard on the record 12 of this proceeding.
You have heard us discuss them in the 13 con text of the interim rule for hydrogen control.
These are 14 questions very much in front of us between now and the end 15 o f this year.
16 Ihose are the only comments I would make in 17 response to what I have hea rd.
18 COMhISSIONER GILINSKY :
I do not have much more to 19 a d d.
I guess I would like to ask, are you familiar in 20 detail with the calculations leading to the predictions in 21 pressures dur ng accidents?
The question I want to ask is 22 simply this.
It seems to me it is one thing to predict that 23 the pressure vill be 10 psi or 20 psi or whatever.
It is 24 ano ther thing to predict the difference between 1 and 2 and 25 3 a n d u.
And it seems to me, I would think that our ability ALCE9SCN AEPCATING OOMP ANY. :NC, 400 VIAGlNIA AVE.. S.W.. W ASH!NGTON. O C. 200:4 (2001 $54 2345
37 1 to predict those sorts of things to that sort of detail is 2 limited, given the complexity of the inside of a containment 3 and the ica and so on.
4 So as I think I have said several times here, it 5 seems reasonable to try to not have these protective 6 seasures and our instructions on igniters depend sensitively 7 on the detailed predictions of such calcula tions but to be 6 based on note general principles.
Ihat is why it seems to 9 me, other things being equal, one would want if there are 10 no other sizable significan t costs attached to this step, to 11 have instructions to turn them on earlier.
12 At some point you said you thought they were 13 equally acceptable signals.
I gather you have at least a 14 mild preference for one.
I 15 MR. BASI.9:
Let me speak to the sensitivity of the 16 analyses.
I wouli agree with you that I would certainly no t 17 van t to defend with my life the exact number of plus or 18 minus the tenth to the psi given in any of our safety 19 analyses for a particular poir.t ja time.
20 However if you look within that containment of the 21 amounts of ener;y that need to be required to change the 22 pressure of psi or so, they are really not very great for 23 tha t volume.
For instance if one sere to just add the 24 hyd rogen gas without looking at the burning aspects at all, 25 you would add creater than 3 pounds pressura to the ALCEASoN REPC ATiNG CCMP ANY. :NC.
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38 1 containment.
That is just a hydrogen gas taken at the same 2 temperature as the containment atmosphere.
3 When you begin adding superheated steam with the 4 hydrogen content to the containment, pressure goes up very 5quickly.
And whether it goes to 7 or 7.5 or 8 is 6 immaterial.
But it goes up well in excess of 3 psig to at 7 least a factor of 2 in most all of the analyses I have 8 seen.
For instance the design basis accident, you are up 9 greater than 7.5 psic within ten seconds of the onset of the 10 accident due to the blowdown.
So we are not just barely 11 making 3 on any of these scenarios.
12 COMMISSIONER OILINSKY:
You think this covers 13 small breaks as well?
14 XR. RASIN:
It covers the small breaks that we 15 have looked at.
We have done some estimates on looking at 16 w h a t wouli happen at smalle r breaks.
laer were done some 17 time ago.
But we have found tha t basically about all you do 181s char.ge the time f rame a little bit, even down to what we 19 would consider as excessive leakage rather than a LOCA.
20 COMMISSIONER GILINSKY:
Would these be 21 conservative calculations or realistic ones ?
22 MR. RASIN.
The calculations that e have done for 23 this hydrogen wor's have been done with CLASSIX.
We have 24 done them conservatively from an engineering s ta nd ;oin t.
We 25 have not conducted them as you would conduct licensing ALCERSCN REPCATING COMP ANY. NC.
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39 1 calculations.
2 COMMISSIONER GILINSKYa Do they take full account 3 of the ice, the possibility of condensation?
4 MR. RASIN:
Yes.
They include the affects of the 5 ice.
From the beginning of the blowdown we take into 6 account th e hea t trahsfer to the ice, the effects of the 7 sprays, the air return f ans.
Ihe CLASSIX Code also includes 8 the structural heat sinks.
So we do look at just heating up 9 the metal and concrete in the containment.
COMMISSIONER GILINSKY:
Thank you.
10 CHAIRMAN HENDRIEs Mr. Riley, it is your turn on 11 12 this last round.
13 MR. RILEY:
Thank you.
14 Mr. Rasin, does the CLASSIX Code assume the 15 homogeneous compositions within the lower compartment, 10 ice condenser and the upper compartment with respect to the 17 concentration of hydrogen?
18 MR. McGARRY:
As his counsel I am going to object 19 to that form.
I have held off on some objections.
I think 20 Mr. Biley of course is free to address the Commission.
I 21 did not think this session was an interrogation of one party 22 by another party.
IHAIRMAN HENDRIE:
No, it is not.
23 24 Tell me where you are aiming and maybe I can help 25 you out and ask him a few questions f or you.
I am unwilling ALOER$0N AEPoAT:NG COMP ANY,;NC, 400 VIAGINI A AVE., S W., W ASHINGTON 3 C. 20024 (202) $$4 2345
40 4
1 to be a blind conduit.
2 MR. RILEY:
I will be very glad to oblige.
3 The entire schema with respect to pressure 4 development and burns and so forth that has been provided by 5 the Applicant in what is known as Exhibit S-3 m akes certain 6 code assumptions.
What I am trying to determine is if one 7 of these assumptions, the in my judgment the unrealistic 8 one, that throughout the course of the accident the hydrogen 9 concentration is uniform, though increasing and then later 10 decreasing through the lower containment, and then a 11 dif ferent one through the ice condensers and still a 12 dif f eren t one through the upper containment.
ould be to 13 CHAIRMAN HENDRIE4 I guess your aim n
14 reinforce your previous comments about possible 15 inhomogeneity in a tmospheric composition at various times in 16 an accident sequence.
17 MR. EILEY:
Not only that; it would be to raise 18 the question of wnether or not we can rely on the 19 predictions of CLASSIX, because if CLASSIX is based on 20 f a u lt y najor issumptions then I think that we are in a 21 position of distrusting its results.
22 CHAIRMAN HENDRIE:
But with regard to the 23 questions we asked this afternoon about feasibility on the 24 one hand, reasonableness on the other of set points for 25 turning the igniters on, I am not sure where that gets you.
ALOERSCN AEPoRT!NG COMP ANY,;NC, 400 VIRGlNIA AVE., S.W, WASHINGTCN, D.C. 20024 (202) 554-2345
i 49 1
MR. RILEY I think that is a very fair 2 observa tion.
I will say this.
It may rela te to the 3 discussion of achieving 3 psi p ressura d:op and the later 4 pressure drop which I think Mr. Rasin said was 6.5 psi at 5 which point the air return fans vent on.
It would have to 6 do with predicting those times which have already been 7 sta ted.
8 CHAIRMAN HENDRIE:
I think once you get enough 9 hydrogen so that questions of hydrogen inhomogeneity are of to interest, we have certainly gone past the time and the 11 sequence at which one would have hoped the igniters had been 12 o n.
13 MR. RILEY:
The thrust of my testimony ve.s that 14 t h a t assumes a known scenario like S2D.
And certainly we 15 did not play out anybody's known scena rio at Three Mile 16 Island because of the various in terven tions that took 17 place.
Just because it is a human possibility that if an 18 accident occurs at McGuire it will not play out a precise 19 scenario, I think that it is fair game to ask for mutations 20 with respect to scenarios.
Tha t would be one.
21 CHAIRMAN HENDRIEs It is certainly fair game f rom 22 your standpoint.
But I have a feeling that that discussion 23 leads us back into the merits of issues which have been i
l 24 adj udica ted and they are on the record, people's points of
)
25 view one way or another expressed.
And it is not so clea:
ALDERSoN AEPCRTING COMP ANY. iNC.
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42 1 to me that it deals directly with the two questions here 2 about the se t point on the igniter triggering.
3 As I understand the thrust of your remarks with 4 regard to particular questions here, I would assume you 5 would be inclined to vote for a lower
- set point barring any 6 good reason not thus f ar discussed f or doing it.
And I 7 think there is a valid point to be made about trip points on 8the fans.
Would that be an unfair characteriration of your 9 view with regard to th e particular point on set points?
10 MR. RIlEY; I think it would be a substantially 11 correct view.
I would feel more comfortable, all things 12 considered, if the pressure set points were lowered.
I am 13 n o t so sure tha t I would want to see the fans go on before 14 3 p sig.
I am not certain that it vould be that relevant.
15 I do think though tha t there is some surviving 16 value in the question tha t I wish to propound to Mr. Rasin.
17 Tha t is it would be helpful I think for the Commission to 18 kno w whether the underlying assumption of their calcula tions 19 of events issumes homogeneity of hydrogen within the several 20 con tainmen ts at any instant in time.
21 The entire ignitor operation is premised I believe 22 on knowing what the hydrogen concentrations are.
If at one 23 small point you have a burnable 10 percent and at other 24 points you have an unburnable 5 percent or unburnable 25 9 5 perce nt, our entire reliance on the ingiter thin; falls ALDERSON AEPCATING COMPANY. !NC, 400 VIRGINIA AVE S.W., WASHINGTCN. 3 C. 200:4 (202) 554 2345
43 Iapart.
In the sense that I felt we were concerned about the 2 efficacy of the igniter system, I would raise tha question.
3 CHAIRMAd HENDRII:
I will tell you what I am going 4 to do.
I am going to use it in a somewhat different form.
5 Rather than turning to Duke Power, I will turn to the people 6 I have worked with for many years and ask whether I can 7 comment about the way in which those codes currently are 8 being hydrogen roncentrations and once more ask him to sort 9 of summarire by seeing whether he sees any significant 10 dif ficulties in set point, safety objection.
11 MR. MrGARRY:
If I :an just jump in, Chairman 12 Hendrie, and give Dr. Mattson perhaps 30 seconds to reflect, 13 I would like the record to reflect that during the 14 exhaustive administrative adjudica tory hearing, the 15 Applicant presented well over 20 witnesses and we discussed to the CLASSIX Code.
'de had the people there who developed the 17 CLA SSIX Code and the underlying assumptions.
18 CHAIRMAN HENDRIEs Fair enough I guess to note 19 t h a t.
20 307er?
21 YR. MAIISON:
I would think that the fact tha t the -
22 Codes do treat the rather large volumes with single nodes, 23 with homogeneous assumptions, would have little tC do with 24 the validity of the 3 psi set point.
You are primarily 1
25 interested in mass addition in the lower plenum.
You add it ALOERSCN REPCRTING COMP ANY, lNC, 400 VIAGINIA AVE 4 5.W., WASHINGTCN.1C. 20024 (202) 554 2345
nu 1 up> you put it in the volume; you calculate what the 2 pr9ssure will be.
3 "he homogeneous sssumption would have a lot to do 4 with the question of can you inert large volumes of pure 5 hydrogen with stasm, isolate it from air, later remove the 6 steam and then bring the air into the previously isolated 7 volume of hydrogen.
That is obviously a he terogeneous 8 question for which the existing codes are not particularly 9 good.
10 I also point out that that is what is known as 11 aultiphase, multicomponent flow at which ve ry few codes in 12 t h e whole world have ever been any good for any problem.
It 13 is a very difficult area of analysis.
You cften end up with 14 not finite element codes of the sort wi th which we are 15 secusemed in MOCA and containment analysis but a lot of 16 qualitative arguments and qualitative analy sis.
17 It is s diffiruit stes.
It is one we have said de 18 would look into.
I do not believe it is particularly 19 germane to picking the 3 psig set point.
20 CHAIRMAN HENDRIEs Or some other.
21 MR. MATTSON:
Yes.
22 CHAIRMAN HENDRIE:
But the Codes do treat the 23 con tainment subdivided into a number of nodes, lower 24 compartm ent I guess, ice condenser, upper compsrtment at 25 lea st-ALCERSON AEDCATING COMP ANY. INC.
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4 1
MR. MATTSON:
You can think of it as a 2 one-dimensional representation with homogeneity in each 3 node, yes.
4 CHAIRMAN HENDRIE:
But in the calcula tion,
5 dif ferent areas in the containment represented by the single 6 node could have diff erent and do have different compositions 7 as the sequence goes along.
It is still less than a highly 8 detailed representation.
On the other hand it is not so 9 cr'ude as to consider the containment i single volume either.
10 MR. MATTSON:
For a burning and an energy transfer 11 point of view, it would be important to treat it in multiple 12 volumes so tha t you could somehow handle the inhomogeneity.
13 But for a mass, an energy addition to determine 14 the pressure, there is no way to sustain much pressure 15 dif ference across such a larcr; space.
The representation by 16 a single f. ode with an assumption of homogeneity would te 17 very good.
18 COMMISSIONER GILINSKY:
How many nodes are there?
19 A ra all the ire rhests lumped together or a re they treated 20 individually?
21 MR. MATTSON:
You are getting into a little more 22 detail than I am close to.
I could ask Mr. Tinkler of the 23 staff to stand up and see if he could address the question.
24 MR. TINKLEF:
The original CLASSIX analysis had a 25 one-node volume of the ice condenser region.
Revised ALoERSCN AEPCAT;NG COMP ANY, lNC, 400 VtRGINtA AVE., S.W, WASHINGTCN. O C. 20024(202) 554 2345
46 1 analyses have modeled that re71on with two nodes, the 2 separate node for the upper plenum of the portion of the ice 3 rondense r region.
4 CHAIRMAN HENDRIEs Mr. Riley?
5 XR. RILEYs Mr. Chairman, do I still ha ve an 6 opportunity to resume on our discourse with respect to 7 questions?
8 OHAIRMAN HENDRIE:
Let me allow you about two more 9 minutes, Yr. 311ey, because I am running out of time.
I 10 have some other appointments, and I sense that the 11 Commissionats hava had a fair chanca to probe into the items 12 tha t were o f interest here.
13 MR. RILEYs I think it would be highly desirable 14 to establish the pressure difference between the upper 15 con tainment and the lower containment at times of maximum 16 flov from the leak.
The reason I say this is that the air 17 return f ans according to the PSAR have a pressure 18 differential of two pounds per square foot.
Psf is the 19 abb revia tion used.
That adds up to a lttle over 20 one-hund red th
'f a pound per square inch.
21 It is my belief that the pressure inside the lower
'111 have a differential much g rea ter than that 22 compartnent 23 with respect to the upper compartment and that the fans will 24 b e ack up if anything.
And this aberration in the flow 25 process ! lo not think has received any consideration.
I ALOERSCN AEPoATING COMP ANY, lNC, 400 VIRGINIA AVE.,5 W W ASHINGTCN, o C, 20024 (202) 554 2345
47 1 think it is a fait question.
2 CHAIRMAN HENDRIE:
I will ask the Commissioners to 3 take it under advisement.
4 Do you have other comments?
5 Peter?
No, sir.
'7 CHAIRMAN HENDRIEs I think we have then achieved 8 the purpose from the Commission's standpoint of the 9 briefing.
I must say I want to thank all of the parties for 10 a useful and, o,n your part, very focused and timely sort of 11 discussion.
I appreciate your coming.
12
- 13. McGAR2Ye At the risk of sounding like a 13 lawyer and cesing in at the last minute, I am going to barge 14 ahe ad anyway, Mr. Chairman, for 30 seconds.
15 Discussions with Commissioner Gilinsky and Mr.
16 R asin, indeed all the parties, centered on two points.
The 17 first one was whether or not it is necessary to lover the 18 s et point for the i; niters.
We are aware of course of the 19 Sequoyah situa tion which is premised upon safety injection.
20 I would like Mr. Rasin to mention just one point 21 to yoc because our people think it is very important.
It 22 really was not brought to your attention.
Rut if indeed you 23 are inclined to go in that fashion and make that a 24 condition, we would feel strongly that that condition should 25 read that the set point would be at safety injection with an ALCERSON AEPCATiNG CCMPANY,.NC.
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48 1 indication of a LOCA.
I think tha t is impo rtan t, based upon 2 our operator training program.
We do not want them, and I 3 am going to turn this over to Mr. Basin f or a second, but 4 there is a reason.
5 MR. BASIN:
We spent all of our time quibbling 6 over our dif f arancas of what was a good enough reason, b ut I 7 wanted to assure that we left you with the fact that I would aconsider to be equivalent to our 3 psig initia tion trigger, 9 a safety injection signal.
What the operator does when he to receives that signal is to immediately begin a checklist of 11 looking to ascertain whether or not there is leakage of 12 coolant into the con tainment.
That I would consider to be 13 aq uivalan t.
14 If we went to just the safety injection signal, 15 period, I would consider that unnecessary but essentially 16 equivalent.
If we were to go to a criteria of every time 17 you get a reactor trip, I think that is just to ta lly 18 inappropriate f or the situation we are dealing with.
I do 19 not think the first thing we ought to have in an operator's 20 mind when he gets a reactor trip is to run for the hydrogen 21 igniter rvitches.
22 COM.".!SSION ER GILINSKY :
When you sa y " indication 23 o f a LCCA," is that a term of art?
Does that represent some 24 specific information that a reactor would receive?
25 MR. 3ASIN:
There are specific criteria in the l
4 At.0EASoN AEPoAT;NG COMP ANY..NC, 400 VIAGINIA AVE.. S W. WA$NINGTCN. O c, 200:4 (202) 554 2345
39 1 procedure.
When a safety injection signal is received, the 2 operator begins verifying that certain things have happened 3 and he has a checklist of things to look for to show that 4 there is in f act leakage of coolant into tha containment.
5 COMMISSIONER GILINS'KY That would be a precise 6 instruction.
7 ER. RASIN:
It is a precise instruction, yes, sir.
8
-33. McGARRY:
Thank you, Mr. Chairman.
9 CHAIRMAN HENDRIE4 It turned out you had the last to word.
11 Ihank.you all very much.
12 (Thereupon, at 3:30 p.m.,
the he a ring wa s 13 adjourned. )
14 15 16 17 18 19 20 21 22 23 24 25 ALOERSCN REPC ATING COMPANY. INC, 400 VIRGINIA AVE., S.W. W ASHINGioN. D.C. 20024 (202) $$4 2345
.s
, m NUCLEAR REGULATORY CO.M4ISSICN This is to certify tha the attachec proceedings before the
,G 1
V COMMISSION MEETING in the satter ef:
McGuire Application for an Operating License Date cf ?roceeding:
June 24, 1981 Decket !!u=b e r :
Place of ?roceeding:
Washington, D.
C.
were held as herein appears, and tha-this is :he criginal Ortnscrip:
thereof f0r the file of the Cec =ission.,
Judith F.
Richard Official Reporter
- f. !y p ed )
JAW A
^
ficial Reper:er (Signature) e l
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l
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