ML19290A260
| ML19290A260 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/31/1979 |
| From: | Ahearne J NRC COMMISSION (OCM) |
| To: | Mattson R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19290A225 | List: |
| References | |
| NUDOCS 7910240315 | |
| Download: ML19290A260 (6) | |
Text
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THE NUCLEAR REGULATORY COM ISS O M
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-n-2226 212 Sunday, Acril 1 (cont'd) of the primary system.
I was responsible for coordinating the former ccncern and Tom Murley brought together the information on the latter.
Our general conclusion at that time was that, for about 1000 cubic feet of pure hydrogen with oxygen just above the threshold value of about 5% at 1000 psi, the " pressure pulse" would be about 5500 ysi.
This came mainly from Dr. Lewis of Pittsburgh (on Monday, Dr. Lewis revised his best estimate downward to about 3200 psi).
The " yield point" of the vessel, according to Tom Murley, seemed to be coming out at about 6000 psi.
Both of these numbers had rather large uncertainties, of which I and Murley were acutely aware.
I discussed these rough results with Saul Levine, who suggested that I tell Chairman Hendrie, who was at the THI site.
I spoke by phone with Hendrie and relayed this to him, expressing the uncertainties to him as ell as the numerical best estimates.
This call occurred ju prior to the meeting with the other Commissioners, which egan at 1350 p.m.
I was requested to give, and did give a briefing on the same subject to the other four NRC Commissioners, all gathered together in the NRC Incident Response Center.
This 15-minute briefing was attended also by Len Bickwit (NRC General Counsel),
and about 15 other NRC people.
This briefing can be found verbatim in the Commission transcripts.
about 1345
- Commission Meetino at IRC with Budnitz (Comm. transcript, oo.94-116) -
Commissioners Gilinsky, Kennady, Sraaford and Anearne ciscuss evacuation scenarios for hydrogen combustion in reactor vessel (pp. 94-99, Thompson concludes mixture is then 5% oxygen and flammable).
Budnitz gives briefing on current assessment by IRC staff of bubble situation (pp. 100-116, concludes mixture is then 3 to 4 percent oxygen and below flammability and talks about consecuences of burning or detonatin early pm
- Milstead (memo) - On Sunday afte -
(April 1,1979), KAPL reportea the results of an is performed with DNR water chemistry code.
Os e code and assuming 10% of the core in boiling KAPL cted a bubble growth rate of 0.4 ft / day.
If 3
it were
' ed the entire core was in boiling the growth rate 3
co e 8 ft / day.
The reason for this low bubble growth was
. at total recombination of the oxygen formed by radiolysis in the reactor coolant was predicted due to the large amount of hydrogen in solution.
KAPL's analysis indicated the buoble contents to be almost entirely hydrogen (from metal water reaction) and indicated a net radiolysis of zero in the reactor q, %$0 A e#J214 f d i h k T C N 1 d w~s+
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2226 213
4 2226 214 Sunday, Aoril 1 (cont'd) have had informal discussions with people like KAPL who independently determined a radiolysis rate in the same ballpark (estimated to be approximately 65 cu. ft per day at STP)*.
Dr. Connors is going to ask KAPL for their view to see if their evaluation of the problem is the same.
about 1500
- Stello (notes) - On April 1 at about 3:00 p.m., I requested the same information of the General Electric Company as I did from Bettis Laboratories.
The GE response was that it is theo-retically possible that oxygen could be added to a hydrogen bubble over the reactor core.
However, they did not consider this would be likely and concluded that they believe that an equilibrium condition may now be present.
They calculated a bounding number for the amount of radiolysis that could take place assuming no hydrogen overpressure.
They estimated that the boundary number is 10 cubic feet per hour at STP but believe this was too' conservative since it was based on BWR data (NEDE-13148 Title KRB Radiolysis Test, Nov. 1970) and that no credit was given for the effects of a back reaction and that the real number is much lower.
They speculated that perhaps there is no net oxygen added.
The following people participated in the evsluation:
Cliff Kent, Jerry Jacobsen, Pat Marriott, Manny Ziegler, and Don Rockwell.
about 1500
- Stello (memo) - (After) I obtained that information (from Bettis and GE)... (I presented it) to the Chairman.
I believe he was persuaded that we need not have a concern for either a burn or explosion of the hydrogen in the reactor vessel.
Following our discussion, he placed some telephone calls to Washington to discuss this information with fellow Commissioner (s).
1552
- Commission meeting at IRC (Comm. transcriot. co. 131-14A) -
Commissioners Kennecy, dracford ano Anearne oiscuss evacuation scenarios for hydrogen comoustion in reactor vessel.
Apparently reaching a consensus to recommend evacuation that afternoon because of combustion potential.
Concern over obvious differences in data coming from the staff.
Decide to advisa Hendrie at site that they are concerned.
Kennedy and Ahearne leave at 1617 hourr, to talk to Hendrie on the telephone.
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2226 215
Sunday, April 1, 1979 'O c f W" d :D about 1430 -
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Benaroya (recollection).
After working the graveyard shift, woke-up in the mote' room thinking about the hydrogen-oxygen problem in the gas bubble. He tried to call the NRC command center in the trailer, but all phones were busy. He finally decided to call the TMI-2 control room and got in touch with Nom Lauben at around 1500. Benaraya explained that normally a hydrogen concentration of 20-40 cf/kg of water is kept in the primary system to eliminate free oxygen. At the pressure and temperature that existed in the primary system, in the radiation field,20 cc of hydrogen per kilogram of water is enough to push the reaction towards recombination. Since we had a large excess of hydrogen, it was very unlikely that any free oxygen would be presert in the gas bubble. Benaraya asked that this infomation be relayed to the NRC trailer.
N. Lauben called back V. Benaroya at the motel saying that he had relayed the information to Mattson, and Mattson told him that this was being calculated in Bethesda.
2226 216 bwaWiA i
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