ML19340C608

Submits Written Record of 790404-05 Actions Re TMI Event: Handled NRC Incident Response Ctr Info Requests Re B&W Components

ML19340C608
Person / Time
Site:	Crane
Issue date:	05/02/1979
From:	Cherny F Office of Nuclear Reactor Regulation
To:	Bernero R NRC - NRC THREE MILE ISLAND TASK FORCE
Shared Package
ML19340C607	List: ML19340C606 ML19340C608
References
TASK-TF, TASK-TMR NUDOCS 8012110493
Download: ML19340C608 (14)

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UNITED L TATES NUCLEAR REGULATORY COMMISSION s

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a ms MEMORANDUM FOR: File FROM:

r. C. Cherny, Sect'an Leader D Mechanical Engineering Branch, DSS

SUBJECT:

RECORD OF ACTIONS, THREE MILE ISLAND ACCIDENT

Reference:

H. Denton Memorandum of April 24, 1979 to NRR Staff As requested by the referenced memorandum, I am herein documenting several requests for information which I was requested to obtain April 4-5,1979 from the Babcock and Wilcox Co. relating to the Three Mile Island Accident.

On April 4,1979, J. Knight was contacted by telephone from the IRC by F. Schroeder and was asked to obtain the following information from Babcock and Wilcox relating to components installed at the Three Mile Island Unit 2 (TMI-2) facility:

1) How long would the pressurizer heaters function in a superheated steam atmospher if they become sincovered?

2) At what system pressure would the reactor coolant pump seals fail?

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3) What is the limiting component of the TMI-2 pressurizer for pressure loading, i.e., what part of the presurizer would be expected to fail first from pressure loading?

Sibsequently, Mr. Knight discussed these questions with R. Bosnak and myself and asked that I obtain the in.~omation through Mr. J. Taylor of the Babcock and Wilcox facility in Lynchburg, Va.

Around no9n of April 4, R. Bosnak and I telephoned Mr. Taylor who was temporarily unavailable hut returned our call within an hour or so.

From this point on, I was the sole MEB telephone contact with B&W on these and several other related questions. When Mr. Taylor returned our call, he designated a Mr. Dave Mars as the person from B&W who wold provide the requested infomation.

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MAY 2 1979 File Early in the afternoon of April 4, I was contacted by Mr. B. Sheron of the DSS Analysis Branch relative to any information I might have about the installation and functional characteristics of the TMI-7 Pressurizer Heaters.

I showed Mr. Sheron the information that was in the MEB copy of

'e TMI-2 FSAR.

I mentioned to him that I had establisned a telephone contact with B&W and was obtaining infomation about pressurizer heater service life, if uncovered and in a steam environment. He stated that for some parametric studies he was doing, it would be helpful if he could have answers to the following:

What is total number of TMI-2 pressurizer heater l

rods?

What is the total mass of the TMI-2 pressurizer heater rods?

What is the heat input of each TMI-2 heater rod?

I stated that since I had already established a contact with B&W regarding heater service life I would try to also obtain the additional information. Shortly after I was contacted l

l by Mr. P. Shewmanski of the Plant Systems Branch of DDR who seemed to be interested generally in the same type of infonnation as Mr. Sheron. I told him that I would inform him of anything I could learn with regard to the pressurizer heaters.

Around mid-afternoon of April 4, I telephoned B&W and related the additional questions to D. Mars.

Late in the afternoon of April 4, B&W called back with some infomation regarding the pressure capability of the TMI-2 l

reactor coolant pump. The attached hand written notes contain more detailed, data, but the basic message conveyed by B&W was that at about 3300 psi system pressure the pump upper bearing would probably overheat. The pump is equipped with three full system pressure seals and complete failure of all three would not be expected before about 4700 psi. B&W consnitted to provide me with the balance of the infomation by phone at home later in the evening.

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~3-J. Knight telephoned the reactor coolant pump information innediately to F. Schroeder at the IRC using the speaker l

phone.with styself and R. Bosnak present. Mr. Knight also pointed out to Mr. Schroeder that the pressurizer code safety j

valv.s would lif t at 2500 psi and should prevent pressurizer pre,sure from going much higher if that was a concern.

Mr. Knight informed F. Schroeder that I would phone the l

answers to the rest of his questions to him at the IRC after B&W called me later that evening.

At 7:05 pn, B&W (D. Mars, M. Burnet, J. Mitchum, an'd F. Rains) phoned me at home. The following information was provided:

1) The TMI-2 pressurizer heater rods were designed to operate sthmerged in water. B&W has no data as to how the rods would pc form in a superheated or saturated steam environment.

The rods have been tested in air and lost about two minutes uncovered. B&W estimates that in a steam environment their life expectance would probably be less than in air.

B&W estimated that at some lower than full electrical input the heaters would probably function indefinitely, but they had not detemined what that input was. They asked me if I thought they should detemine it, and noted it would require a fairly large computational effort to do so.

I requested that they do so and phone the response to me on the morning of 4-5-79.

2) As far as the " weakest" portions of the pressurizer for pressure loading was concerned, B&W advised that the gasket sealing the manway access cover near the top of the vessel would fail first from high pressure followed by the seal welds of the heater rods to i

the vessel penetrations. They advised that they were l

calculating the exact failure pressures and would inform me of their values on April 5,1979.

3) With regard to the pressurizer heater neerical and functional data that Mr. Sheron and Mr. Shemmanski were interested in, I was informed as follows:

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4-MAY 2 1979 File a) Each heater rod has an electical output of 14 KW.

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b) There are 39 heaters in each bundle.

c) The total heater output of each bundle is 7638 KW.

d) The total mass of the heater rods is 897 lb. and each heater rod weighs 10 lb. The total mass includes support plates, etc.

Imediately after the B&W call I telephoned F. Schroeder at the IRC and gave him the infomation per items 1 and 2 above which he had requested. I noted that B&W was going to try to detemine at what reduced power input the pressurizer heaters could operate uncovered indefinitely, but based on our discussion I had the impression that obtaining tnis information was not a high priority item at the IRC.

The next morning I conveyed the infomation on the heater rods per item 3 above to both Mr. Sheron and Mr. Shewmanski.

After conveying this infomation, either Mr. Sheron, Mr.

I Shewmanski or both, I cannot recall at this writing and sly notes do not indicate, but in any event,.liscussions with both indicated a need for the following add. nal clarifications and infomation on the pressurizer heater rods:

Does each single heater rod bundle containing 13 rods weigh 897 lb. or is this the total weight of the 39 rods?

What is the diameter of each heater rod? What is the petch that the rods are installed on?

What parameters are being measured in the reactor coolant system for cycling the heaters on an,off?

Later in the day B&W called me back (~ afternoon and D. Mars, I believe) with the following responses:

Each pressurizer heater bundle of 13 rods weighs 897 lb.-

The diameter of each rod is 0.660 plus or minus D.005 inches.

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nt File MAY 2 579 The heater rods are installed on a triangular pitch of 2.375 inches center to center.

During normal plant operation the pressurizer heaters cycle on and off in response to pressure measurements only.

Electrically speaking the three groups of heater rods are wired into four banks as follows:

BK #1 - 126 KW capacity cycles on at 2135 psi and off at 2155 psi.

BK #2 - 504 KW capacity - cycles on at 2130 psi and off at 2140 psi.

BK #3 - 504 KW capacity - cycles on at 2115 psi and off at 2135 psi.

BK #4 - 504 KW capacity - cycles on at 2100 psi and off at 2130 psi.

I conveyed this information to both Mr. Sheron and Mr.

Shewmanski.

Later that evening I was contacted at home by a Mr. F.

I McFadden of B&W with the following information regarding the failure pressures for pressurizer vessel components:

Manway Cover Gasket - 3500 psi Seal Welds on Heater Rods - Significantly higher but not quantified.

I queried Mr. McFadden d>out the status of the determination of the reduced power input at which the pressurizer heaters could be operated at indefinitely a steam environment.

He indicated that he did not think much progress had been made on this due to other high priority activities. Because there did not appear to be an urgent need for this information based on all the discussions I had participated in, I told Mr. McFadden that I felt they should spend their time in other areas unless we called them back and expressly requested they proceed with the determination.

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Dn MAY 2 570 File. 73 last pressurizer information I decided not to transmit to the IRC because it seemed irrelevant in view of the pressurizer safety valve set-point of 2500 psi and the Reactor Coolant Pump bearing overheat pressure which was more limiting at 3300 psi.

F. C. Cherny, Section ader Mechanical Engineering Branch Division of Systems Safety cc w/att:

D. Crutchfield, NRR cc w/o att:

F. Schroeder, DSS J. Knight, DSS R. Bosnak, DSS B. Sheron, DSS P. Shewnanski, DOR

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