ML19309G313
| ML19309G313 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 10/29/1979 |
| From: | Zebroski E METROPOLITAN EDISON CO., NRC - NRC THREE MILE ISLAND TASK FORCE |
| To: | NRC - NRC THREE MILE ISLAND TASK FORCE |
| Shared Package | |
| ML19309G303 | List: |
| References | |
| TASK-TF, TASK-TMR NUDOCS 8005050541 | |
| Download: ML19309G313 (5) | |
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Intsrview Summary 8005050 5 N Dr. Edwin Zebroski Director of Nuclear Safety An4 ysis Center l
Electric Power Research Institute P. O. Box 10412 Palo Alto,' California 94303 Telephone:
(415) 855-2061 The information listed below is a summary of an interview of Dr. Edwin Zebroski, Electric Power Research Institute (EPRI), conducted by Mr. Hartmut E. Schierling of the U.S. NRC Special Inquiry Group (SIG) for the Three Mile Island tnit 2 (TMI-2) accident. The interview was conducted on September 27, 1979 at the EP.RI offices in Washington, D.C.
Dr. Zebroski was shown a copy of,the SIG Witness
.a Notification (Attachment A). He was told that the interview was' voluntary, that
- notes would be taken and that he would be provided with a copy of this report.
Because Dr. Zebroski had to return to his home office in Palo Alto, California that day, the interview was terminated at about 8:30 p.m.
He stated that he would provide additional information on the subject by preparing a tape recording which he will send to the SIG.
The following information was given by Dr. Zebroski in response to questions by Mr. Schierling on the subject of his participation in and knowledge of the industry support effort.
Zebroski was informed.of the TMI-2 event.at his office in Palo Alto, California on Thursday (3/29) in a telephone call from either Floyd Culler (EPRI) or MQt Levenson (EPRI) who were both out of town. They had been contacted earlier that day by H.
Dieckamp of GPU.
Zebroski was asked to assemble a group of people who could assist in the analysis of the TMI-2 event.
2 Zebroski set up a ready room at the'EPRI offices, assembled blueprints, Safety E
Analysis Reports and other TMI-2 related documentation and background information, and initiated a general TMI-2 plant familiarization.
R. Keaten of GPU in Parsippany, N.J. sent additional drawings by special messenger to Palo Alto during the night of' Thursday / Friday. The first questions posed to EPRI by GPU were how to eliminate the gas bubble (s) that was assumed to exist in the primary system and how to achieve natural circulation in the reactor coolant system (RCS) (because of a potential loss of all RCP flow).
Based on the little information available to hbn at that time, he had developed a preliminary sequence of events by Thursday evening, which 'was put_on a blackboard, and of which Zebroski then took a picture. However, without additional information, he was not able to understand the plant situation sufficiently to give meaningful advice to GPU on the above two issues.
t On Friday (3/30) Zebroski was called by Keaten of GPU asking about a method to eliminate the bubble (s) from the system. He recommended the use of the reactor cool-ant letdown system as preferred over venting via the pressurizer. Meaten also asked about the solubility of hydrogen and oxygen in the RCS.
Other people had discussed the possibility of adding sodium thiosulfate to the RCS as a hydrogen scavenger.
Zebroski advised that in the existing radiation field and under' the existing RCS pressure oxygen was an excellent hydrogen scavenger. The potential of a hydrogen f
explosion was not mentioned at all in that telephone call. -
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Based on the additional information provided by Keaten, Zebroski was able to refine his sequence of events by Friday.
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On Saturday again he was appraised of the plant status by H. Dieckamp who also re-quested that he cdme to the site as early as possible to assist GPU in the evalua-i tion of the plant condition.
Zebroski came by the first available flight.' On his.
arrival in Harrisburg, Pa. early on Sunday, there existed great confusion among j
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the individuals who were assembling at the Air National' Guard in,a group that ev nt-ually became the Industry Advisory Group (IAG).
The developments since March 28 and the current plant status were not fully known to the group which by Sunday evening cessisted of about 30 people.,Zebroski recalls three meetings on Sunday in which the IAG participated. The first one, at some time in the early afternoon, was a plant status briefing by H. Dieckarp and R. Keaten of GPU.
The IAG was asked to put forth their thoughts on the following priority. issues:
how to cope with the bubble, including identification and size of bubble what is the degree and physical condition of the reactor core how can natural circulation be achieved what is the leakage path for the radiation measured offsite The second meeting took place at about 7 p.m. and was principally a briefing' by mem-bers of the NRC (D. Ross and R. Mattson) on how the NRC perceived the plant status -
and what the major concerns were.
H. Dieckamp of GPU was also in attendance'.
L Zebroski recalls that the issue of the bubble was a major subject of the eeting.
It was his opinion, even before coming to TMI, that the explosion issue was a non-problem because the existence of oxygen as postulated was physically impossibl's due to the l
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4 He had confirmed his opinion earlier with experts existing hydrogen overpressure.
He stated that his opinion was based on his extensive exper-at ORNL and at EPRI.
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6 ience, including research on hydrogen-oxygen radiolysis while working on PWR He did not inform GPU or the NRC earlier of his evaluation, be-systems at KAPL.
cause he was in travel status on Saturday and was not aware of the panic level associated with the " bubble explosion" potential. He provided the NRC with refer-ences relating to the issue (including references to the Geneva-Conference or Peaceful and believes that,in part as a result of these discussions, the N' RC Uses of the Atom)
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I changed its opinion regarding the explosion potential.
Attendees included.from the NRC i
The third meeting took place later on Sunday.
I D. Ross, R. Mattson and R. Vollmer; from GPU H. Dieckamp, R. Arnold and J. Herbein (Met-Ed); F. Stern from CE, and E. Zebroski and M. Levenson from EPRI. Th,is was an executive type meeting in which priority issues and IAG interaction were discussed.
It was an Zebroski briefly discussed some aspects of the operation of the IAG.
r informal, loosely structured organization. The group was represented at the daily meetings of the Technical Working Group (TWG). This group included representatives from all elements of the GPU Recovery Organization under R. Arnold. The group pro-vided information exchange, plant status identification, and recommendations for i
there was a Technical operations meeting to discuss how such actions. After meetingq recommendations should be implemented.
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In general there were no problems of presenting at the TNG and implemedting recom-i mondations reached by the IAG. There were exception. 'Zebroski requested an on-time l
readout of all in-core thermocouples, located approximately 6 inches above active l
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fuel.
He intended to use this information 'or noise analysis to determine if there f
was any local in-core boiling. (Thermocouples can detect, a hot liquid stream at the core exit resulting from condensation of superheated bubbles created by local boiling; I
s-ithin the core.)
Babcock & Wilcox had supplied the IAG with a sample of the ther-1 mocouple. Zebroski made the request for the TC readout on about April 2 or 3.
How-eve', action by GPU was taken only after he talked with ~the NRC (V. Stello).
r At their request N. Ackerman of Technology for Energy came to TMI and installed a 20 channel brush recorder. Zebroski stated that Ackerman provided excellent assistance on all issues involving diagnostic efforts.
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