ML20024B446
| ML20024B446 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 11/30/1980 |
| From: | Rosalyn Jones GENERAL PUBLIC UTILITIES CORP. |
| To: | |
| References | |
| TASK-*, TASK-GB GPU-2519, NUDOCS 8307080748 | |
| Download: ML20024B446 (6) | |
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gal / 6)9 u626 1 filling the systa: up with water and rhey put vater above 2 all the tubes and you are rising up in the plenut of the
.n s 3 stean gen era tor it the hot leg, that steam which is #
4 controlling your system pressure is not seeing the cold tube 5 surfaces and effectively you do not have heat removal via.
6 those.
r 7
DR. JORDAN:
I,et's assume nov ve have a two-phase Sin the core, as you centioned, as one of the vays in which 9you can establish the boiler condenser mode.
We have 10 boiling at the top of the core -- staa: being generated 11 there.
Nov vhy doesn't that steam see the t,ubes over in the
- 2 sten: generator?
13 EITNESS JONES:
That steam -- see the condition 14 rou are describing is a condition where you aEe not really 15 refilling the system.
If you have substantial boiling in 16 the core you vill not be refilling the system in all 1711k elih ood.
la DR. JCEDAN:
I see.
And under those circumstances tgyou say the boiler condenser mode vould work.
20 WITNESS JONES:
Yes.
21
'DR. JORDAN:
All ri;ht.
What kept it from vorking
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22 here?
Was there not a bubble of gas or bubble of steam but A
23a bubble of water in that hot leg?
24 WITNESS JONES:
let :e try to take you back.
Keep 25 the figure a vailable in the diagra= which was given us by 8307080748 801130 PDR ADOCK 05000289 T
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At about one hour and forty minutes the last 2 reactor coolant pumps were tripped.
3 Okay.
If you look at the steam generator levels 4 in that timaframe, you could see that there were about 5from about one hour and forty minutes on to somewhere around 6 six hours they vara being maintained at less than fif ty 7 percent of the operating range.
This is the secondary stage 8 stea: generator levels.
This is one up from the bottom on 9 the chart.
10 DR. JOEDAN:
I see.
This is the one that's colors.
11 WITNESS JONES:
That's right.
But both graphs (2's h o w up to about six hours.
You had steam generator levels i 13 on t he or d er o f fif t.y percent or less.
14 DE. JORDAN:
Yes.
15 WITNESS JONES:
Translating that over to the 16 figure in my testimony, that roughly corresponds to the line 17 which is identified as the steam generator thermal center.
18 DR. JORDAN:
I see.
19 VITNESS J0KES:
Now, at the time ther turned off 20 the pumps thev did get a condensing process occurring within 21 the stes i en. ator, because the primary system pressure 22 started co us.raase from' roughly 1100 PSI and dropped down 23 to a pproxi=ately 6 00 PSI.
24 DR. JORDAN:
That's number nine.
g 25 WITNESS JONES:
Eirht or nine.
It's the graph A:.DERSoN REPORTING COMPANY,INC, 400 VIRGINIA AV~r S.W., WASH:NGToN. 0.C. 20024,(202) 554 2345
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4628 f(1 labeled Reartor Coolant System Pressure.
You can see 2 between so=evhere on the order of one hour and thirty-five 3 or f orty minutes down to about two hours and ten minutes the 4 syste: pressure dropped.
What that is indicative of was 5that there was heat removal occurring in the stea:
6 generator.
And in fact there was a condensation process 7 occurring.
8 DR. JORDAN:
I see.
So you say that at that time 9 the condenser mode was operating?
10 WITNESS JONES:
Right.
But the problem with it 11 was that there was -- you had maintained -
,vell, when you 12 tripped the pumps during the accident, at the time they were 13 tripped there was very little inventory remaining in the 14 pri= ary syste=.
15 DR. JORDAN:
Yes.
16 WITNESS JONES:
The boiling which was occurring in 17 the core and the condensation was essentially transferring 18 mass fro: th e core and allowinc it to collect in the lower is regions of the system.
That is, the regions below the steam 20 generator ther:a1 center I was talking about and the water 21 w a s essentially being transferred and trapped within the 22 1over portions of the steam generator and was not 23 recircula ting.
24 DR. JORDAN:
Well, the solid water.
But steam was 25 being recirrulated.
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1 WITNESS JONES:
The steam was circulating and 2 being condensed.
But the boiler condenser process relies on 3a stea: generation within th e core, the condensing in the 4 steam genera tor, and then a subsequent water flow back into 5 the system.
And that water flow comes from mali:taining the 6 primary system inventory and keeping the stea: generator 71 eval above the 95 percent -- around the 95 percent range.
8 And because they kept the level down at 50 percent 9they essentially filled up that bottom region and then they to stopped heat' transfer when you had covered up th't stean a
11 surf ace because the inventory of the seconda ry side was lov 12 'and was not above the reactor coolant pu=ps to allow water 13 to flov back in.
14 DR. JORDAN:
I see.
So that the cold leg there 15 vould be filled up less.than the pump. Is that what you're 16 sa ying ?
17
'JITNESS JONES:
Right.
And then when that happens 18 you stopped heat transfer and in fact that is the start of 19 the pressure rise indicated at about two hours and ten 20 minutes on the pressure curve.
And then later on the 21 pressure continues to increase because they stop.
They 90W 22 close up th e -F-:
a an d y o u g e t the hydrogren generation, 23 whirh just accelerates the repressuriration process.
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24 DR. JORDAN:
How the heat transfer shouldn't j 25 really have stopped.
The boiling would continue in the N.CERSoN REPORTING COMPANY. INC.
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. still 1 core, even though it was not at the top.
There vould 2 be steam generated. That steam should have gone around and 3 condensed over in the steac generator.
And so there,vould 4 he cooling a t least to the level of the core at which the 5 vater vas existing.
Is that correct?
6 WITNESS JONES:
Yes.
There was cooling in the 7 steam generator region, you knov, up to the elevation where 8 the secondasy side level vas.
But ultimately you did kind 9of close off the heat transfer because you built up a vater 10 level in the primary system which was equal to the level in 11the secondary systet.
So that there was no way to get the 12 stea m to transfer energy to that colder water on the steam 13 gene rator side.
You had a block where you could not bring 14 th e stea: in contart with the cold tubes covered with liquid 15 on th e secondary side.
16 DR. JORDAN:
Were these secondary sides of the 17 steam generator -- vas that not kept at fairly high level by 1sthe operatisn of the auxilliary feed water pumps so that all 19the time -- vell, I see you're saying -- nov let's look at 20 th e -- which chart is it that shows --
- !TNESS JCNES:
This is the one two up from the 21 a
22 bottom.
As you can see, until about six hours or so, 23 neither stea: generator was being maintained at a level 24 where you would have N
25 DR. JORDAN:
You just didn't have enough surface A' OERSON REPORTING COMPANY,INO, 400 VIRGINI A AVE., S.W., WASHINGTON. O.O. 20b24 (202) 554 345
o 4631 1 to transf er the amount of heat that was being generated.
2 WITNESS JONES:
They had enough surface.
It was 31n the wrong place.
It was in the bottom of the generator.
4 They needed to raise it up above the pump. If they had that 5 surf ace above the punp a couple of feet then they would have 6 had a condensing surface where every drop of steam condensed 7 vould then j ust push a pound of wa ter -- ano ther dro p of avater -- back over the pump to keep the circulation 9 established.
10 DR. JORDAN:
So it was the water side, then, that 11 you lost circulation?
12 WITNESS JONES:
Yes.
13 DR. JORDAN:
The water couldn't replenish the 14 vater in the core.
15 VITNESS JONES:
That's right.
Because a high is enough steam generator level was not maintained.
17 DR. JORDAN:
Okay.
I think I understand.
I von't 18 guarantee to remember that.
19 BY F. S. WEISS:
(Resuning) 20 Q
rou discussed the repressuriration of the system 21 starting at about two hours and ten ninutes.
Is there any zgalternative explanation to the one you gave?
And the reason 23 f or tha t, I'n specifically referring to the block was closed 24 a t tha t time.
1 25 A
Well, if you look at the chart,, th e block valve l
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