ML19309G245
| ML19309G245 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/20/1979 |
| From: | Flint J METROPOLITAN EDISON CO. |
| To: | |
| Shared Package | |
| ML19309G241 | List: |
| References | |
| TASK-TF, TASK-TMR NUDOCS 8005050464 | |
| Download: ML19309G245 (6) | |
Text
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e 8005050 John Fline 1550 Ers. April 20,1979 Conducted By:
E. F. O'Connor O'CONNOR:
John would you briefly state when you came on site, what your role is at IMI and what you saw as you entered the control room the morning of the 28th of March.
FLINT:
My position on site was to be Physics Test Coordinator to the.Unic 2
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startup. Prior to this transient, I was writing the Unit 2 startup report.
At approximately 08:30 on the 28th of March, I arrived at the North Gate to the Island only to be stopped due to security personnel restricting anyone from coming onto the Island. During approximately the next 20 minutes to half hour I attempted to have one of the security personnel contact the control room to find out if my services were required.
Ihis is based on the fact that I am f=414mr with the ' reactor core physics of the unit. At approximately 09:00 permission was received for me to go on the Island.
I immediately drove to Unit 2 and entered through tha Unit 2 search trailer and went directly to the control room. Upon entering the control room I noticed the normal alarms were lit, the typer was printing out as normal af ter a turbine reactor trip.
I also noticed that the emergency team fer a radiation type of emergency was in attendance in the control room.
In talks with the control room personnel primarily Bill Zeve, Shift Super-visor, Ed Fredrick, Control Room Operator, and Lee Rogers, B&W site
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rarresentative, quickly established th t conditions were abnormal for t W type of a transient.
In talking with these personnel and looking at the console indication and the computer printout note,d that the hoting temperatures for the primary' system were in excess of 620F, that the oldleg temperatures significantly varied from this, they were quite a bit cooler.
Pressure was low in the reactor coolant system. All the con rol rods were on the bottom. The indication for the source and intermediate range appeared to be normal for a shutdown condition.
I did, however; notice the two blips on the recorders for the source and intermediate range, Ed Frederick informed me that they had thought at the time that they wersioing critical and that they added boron.
At th:n time I informd him that in all probability that was not the case, that there had been a change in the leakage flux path from the reactos core to the detectors and it was not in, fact a case of the reactor gcing critical aga An.
Looking at the recorder that prints out the UTSG's and Reactor Coolant Temperatures on wide range 0-800F there were several temperatures; that were reading from 770 to 800F in the Hotleg of the reactor coolant system.
Since these thermocouples are not normally calibrated at that range, I knew that the temperatures were high but did not totally believe the indication.
Ivan Porter, the Mac-Ed I&C Engineer showed me a setup where he was reading approximately 243 OEMS which converts to approximately 725F on an RTD that he set up especially off the side of the control rocm.
Talks with various personnel in the control room, Gary Miller, and the rest of the operations personnel infor=ed me of the sequew ; of events that had lead up to this position.
At the time I talked with Ed Fredricks, we were convinced that we in fact had a solid steam bubble in both loops of the hotlegs. A:: the time m
l they attempted to initiate the filling of steam generators to indece natural circulation or at least remove enough heat to collapse a bueble sufficiently to run the reactor coolant pump.
Page 2.
John Fline O'CONNOR:
John, let me ask you a question at this point. You said sometime af ter you got there which was after 9:00 they started to attempe natural circulation, from that can I infer that the control room staff up to that time was not tryi:ig to establish natural circulation?
FLINT:
There was some doubt at that time as to whether they were trying to establish natural circulation or not. They were filling the generators to some extent, but it was not sear that they were going to try to establish natural circulation.
O'CONNOR:
That was not their goal?
FLINT:
I didn't infer that at the time.
I talked to several different people and I can't remember exactly who said what, but some of them said they were merely filling the generators to obtain a level in them and to remove some heat, others said they were trying to induce natural circulation and some said that they were doing it in order to just cool enough to try to run a pump.
I think most people at this ti=a did not believe that there was in face a superheated steam bubble in the hoclegs.
O'CONNOR:
And this is after 9 o' clock.
FLINT:
Sometime after 9 o' clock, between approximately 9 and 9:30.
O'CONNOR:
What was the control room staff trying to do at that time to reestablish some flow in the reactor coolant system?
FLINT:
The operators reported to me that they had attempted to run reactor coolant pumps, had seen a ' low current indication on the pumps, had not observed any flow indication of any significant degree and, therefore, had concluded that the Reactor Coolant Pumps were totally steam bound or that the pumps were cavitating and not operating correctly.
O'CONNOR:
Were they trying to increase pDuc pressure to prevent pumps from cavi-tating?
FLINT:
Shortly af ter this period of time there was an attempt to pressurize the syeten and to collapse the bubble that way.
I explained to them at the time, if the te nperatures ce were seeing were atrjvay near true, we could not f.n fa n c.ollapse the bubble.
It would be in excess of allow-able presetres ewt if we gaged the tode safetie e.
The code safeties would lif t before un could reach cl.is pressure nnd the system itself was not designed for this pressure.
O'CONNOR:
That was bescause tht iteam bubble ias superheated.
l FLINT:
That is correct.
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d Page 3.
John Flint O'CONNOR:
So, John, in summary you are saying that the temperature of the steam bubble was so hot that its saturation pressure was greater than the i
set points for the code safeties and even if they charged the system up the code safeties would have lif tad before they could have suppressed the bubble.
FLINT:
That is correct. The rough approximation would be to take in excess of 3000 pounds, and the code safeties are. set for 2400 to 2500 psi, so there would be no way we could have done it.
Ac,that time for approxi-mately 1-1/2 hours, they. were dumping out of the atmospheric dump on
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the A generator. We then. received a call that stated the Governor re-quested that the valve be closed immediately.
The request was in a form that made it a demand. Gary Miller complied and at that time was i
preparing to go to talk with the Governor.
0'CONNOR:
Do you recall why we were lif ting the atmospheric dumps?
1 FLINT:
We were using the atmospheric dumps to try to steam the A generator and remove enough heat so that we could use this as a heat sink and collapse the bubble that way; induce natural circulation.
O'CONNOR:
Both the vacuum and the condenser weren't available at that time.
FLINT:
No, we had lost the amriliary boiler and they were attempting to regain it. I believe they gained one boiler for a time, lost it and it was quite some time before wt got both boilers back.-
O'CONNOR:
What did we use as the heat sink once the plant staff stopped dumping steam to the atmospheric dumps at the request of the Governor.
FLINT:
Some of the heat was removed by dumping through the electromatic relief valve into the building, some of it was taken away with the filling of the generators. About this time the level in the B generator was also increased.
They did dump some down into the condenser on the bypass valves, but that was not in that portion of time.
I just don' t remember exactly which sequence. That was our only method of heat removal at that time. Finnfly verified, in fact, that we could not collapse the bubble, the pressure was then reduced again. At that point in time they tried to reduce the pressure to the point where we could go down on the core flood tanks. There was some concern that the core was not, in fact, covered.
I felt that it was since the leakage flux as seen by the source range channels appeared to be in a normal range for a shutdown condition considering the length of time we had been shut down.
However, as a precaution, the pressurr was reduced.
The core flood tanks slowly equa.
lized with the system and we did not see a significant pressure change i
or a rar,1d dropping of the core flood tank levels.
They feed directly
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into the domicomer annulus of the reacror vessel itself.
From that we presured that the core was covered and that we were essentially feeding in anel either bypassing the core or just barely coming out c;. the core, comin g back through the legs and dumping out the pressurizar for cooling
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water.
We were not getting anything up through the loops themselves.
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Page 4.
John Flint FLINT: (conc. )
We did have a high pressure indication in the reactor building somewhere along this length of time. We had the alarm for containment isolation about the same cima there was a double thud. At the time it was not thought to be from the building, at least I personally did not thi* it was from the reactor cournim=nt building.
I thought that it was the ventilation dampers cycling.
It was very close to that sound, and since we had been in and out of respirators due to levels in the control bn41 ding I just thought somebody had cycled the ventilation dampers again and related it to that.
The reactor bnfiding spray pumps came i
on in normal actuation sequence for high building pressure; they were bypassed and later shutdown.
During this portion of time we finally managed to get the A leg temperature decreased to where we could see the hotles temperature on scale.
The operator then elected to try to go over to another leg and collapse the B side, in doing so he lost the gain we
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had made on the A side, and the A side hocleg again went off scale.
Somewhere along in here we finally did see som changes, the hotleg temperature was coming down, the coldlag temperature was going up indica-ting that we were getting some type of heat transfer across the A Steam Generator.
Later in the afternoon, we were requested to once again try to collapse the bubble by increasing the pressure, once again we tried to explain that we had tried that in that morning.
Pressure had been i
increased to approximately 2000 pounds and it had not worked, and the camperatures at this time were still not significantly different from those earlier in the day but we could not pursuade them that this could not be done.
Being unable to convince offsite personnel that the pressu-a increase would not collapse the bubble, we went ahead and increased pressure to approximately 2300 pc mds chirging with the makeup pumps.
We gradually throttled back on one pump until we achieved this and held it for a considerable period of time.
This did not collapse the bubble, however, by this time due to early indications of the coldles temperature increasing and the hotleg temperature coming down in A loop, we felt that we had enough water around the pump at the time that we could run one I
of the A loop pumps.
The A loop pump was chosen for two reasons, 1) we had a better chance of establishing circulation there, and 2) the pressur-1:er spray line comes off there which would give us nixing in the loop and help to bring the temperatures down a little more rapidly plus allow us to get better boron samples if we had to take them out of the pressurizer system. After trying and failing to start Reactor Coolant Pump 2A, we went to lA and ran it for approximately 10 seconds.
This was long enough to indicate to us that the current appeared to be in the normal range and that flow was in fact verified in the loop. We then shut the pump off and let it sit for approximately 15 minutes. The 15 minutes was based on the fact during normal startup-due to the surge currents; we do not want to start and stop the pump anymcre frequently than this.
O'CONNOR:
Why would the pump stop af ter just a few seconds of running?
T J
Page S.
John Flint FLINT:
We were not certain what would happen. We might pull the steam bubble down into the pump and cause severe cavitation or possibly with a rapid pressure change and mass density change fail the seals in the pump.
We, therefore, just wanted to verify we were moving water and were ob'mf ning some mixing.
Once we had collapsed the bubble a little further, the pump could be run ecctinuously as this would have verified we could do it without any signiMeant problems.
Since the pump appea-ed to be norma the pump was restarted and we saw the expected pressure decrease and flow rate that we expected.
The pump current was normal at approx-imately 600 AMPS.
The pressure decrease was due to the collapsing of the steam bubble and we saw the A loop temperatures on the hocleg come down, the coldleg temperatures were going up indicating that we did have flow and miving.
The smooth trace on the flow plus the pump current indicated that we did not have any serious steam bubble problems, that in fact we were pumping primarily water, if not entirely all water.
That period of time the pump was left running to mix the system up.
In this period of time we started drawing a vacuum on the condenser and were preparing to get the aux. boilers back on line so that we could start feeding back into the condenser, the normal method for cooldown.
After a pericd of time Usirly late in the evening) we established the bubble in the pressurizar, we brought the temperatures in the 3 loop hotleg down on scale, and were getting some small amount of circulation through the B side as well.
One point which I forgot to mention earlier, was that t.ortly after I came in we also started en114ng up on the computer the 1; : ore thermocouples attempting to establish what had happened in the ctre. Many of them were indicating questionmarks which indicated that tey were greater than their 700F range.
Only one or two seemed to indic te that they were in fact bad.
These temperatures were monitored for the rest of the day to follow what was happening to the core.
O'CONNOR:
John, were you functioning as a B&W employee during this event or were you just there providing advice.
FLINT:
I was primarily there providing advice not as a B&W employee, I was still on services to GPU and felt that I was filling the role of advice and consultation to the customer from that standpoint.
I was, however, inter-acting with Lee Rogers providing him with the physics parameters.
O'CONNOR:
Where was lee?
I l
i FLINT:
Lee was in the control room during this time. Frequently he would be in the meetings with George Kunder, Gary Miller, Mike Ross, Bill Zewe and the rest of them establishing what they were going to do next.
I was i
primarily working with the operators themr.:'.ies, monitoring parameters and he' ping them try to assess the actual situation in the core and the i
primary system status.
0'CONNOR:
I see. Was B&W, Lynchburg communicating with Lee Rogers?
FLINT:
There *:as an open line to B&W, Lynchburg on a continuous basis, as well as ar open line for the NRC to communicate with their personnel, and open lines direct over to the observation centen and to other personnel on the l
outside for advice from the GPU and Met-Ed facilities.
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Page 6.
John Flint O'CONNOR:
Were you in a posit::on to observe how the emergency plan was being carried out?
ILINT:
During the portion of time that I was there, it seemed to be extremely wen organized, personnel knew what they were required to do, there was excellent communications between Unit 1 control room which was set up
'as the emergency control center.
The Unit 2 control room, the offsite personnel, and I would say that an aux operators, I&C personnel and HP that were associated with this, were functioning extremely smoothly during this portion of time.
O'CONNOR:
How would you describe the atmosphere in the control room during the period of time that you were there?
FLINT:
I would say that the personnel were extremely calm and weH organized.
Late in the af ternoon it had a tendency to get a little noisy in there.
when the immediate problems were over and we had a large number of per-sonnel in the control room by this time. We had a large number of NRC personnel, we had at least a shift and one half of personnel, plus additional personnel from Unit 1 and so forth.
It got a little noisy from that standpoint, but it was still very well controlled and well organized.
O'CONNOR:
People were not running around not knowing what to do, not p=Wng?
FLINT:
No, no panic, especially since frecuently announcements were made over the page system to let all personneA know what was going on.
Unnecessary personnel were released either to their homes or were mobilized at the observation center for assistance if necessary. The only personnel that remained on site were those that were absolutely required, and since they were van informed of what was occurring and since most people were in one of the two control rooms, there was no problem with people appearing not to know what they were doing.
O'CONNOR:
Are there any other observations t.at you would like to get into the record?
FLINT:
No, I do not believe I have any other observations or remarks concerning the. incident.
O'CONNOR:
Thank you very much John, I appreciate it.
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