ML19221A612
| ML19221A612 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/02/1979 |
| From: | Cherny F Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| TASK-TF, TASK-TMR NUDOCS 7905230408 | |
| Download: ML19221A612 (6) | |
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5'AY 2 1979 h tral File
?iRR Mdg.-Ej le - M. Groff DSS:MEB Rdg. File ME",0RANDUM F0't: File FROM:
F. C. Cherny, Section Leaaer Mechanical Engineering Sranch, DSS
SUBJECT:
RECORD OF ACTIONS, THREE MILE ISLAND ACCIDENT
Reference:
H. Denton Merorandum of April 24, 1979 to NRR Staff As reauested by the referenced memorandum, I am herein docunenting several requests for infomation which I was requested to obtain April 4-5,1979 from the Sebcock and Wilcox Co. relating to the Tnree Hile Island Accident.
On April 4,1979, J. Knight was contacted by telephc'a fron the IRC by F. Schrceder and was asked to obtain the following information from Babccck and Wilcox relating to conponents installed at the Three Mile Island Unit 2 (THI-2) facility:
- 1) How long would the pressurizer heaters function in a superheated steam atmospher if they become uncovered?
- 2) At what systea pressure would the reactor coolant pu=o seals fail?
- 3) What is the liniting component of the T7tI-2 pressurizer for pressure loading, i.e., what part of the presurizer would be expected to fail first from pressure leading?
Subsecuently, Mr. Knight discussed these questions with R. Bosnak and myself and asked that I obtain the information through Mr. J. Taylor of the Bitcock and Wilcox fccility in Lyncicurg, Va.
Around noon of April 4, R. Bosnat and I telephoned Mr. Taylor wno was '.eaporarily unavailable but returried our call within an hour or so.
From this point on, I was the sole MES telenhone contact with BMJ 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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File M4(
2 1973 Early in the afternoon of April 4, I was contacted by Mr. B. Sheron of the DSS Analysis Branch relative to any infornation I niqht have d> cut the installation and functional characteristics of the TitI-2 Pressurizer Heaters.
I showed Mr. Sheron the information that was in the MEU copy of the TMI-2 FSAR.
I centioned to him that I had estaolished a telephone contact with B&W and was d>taining information 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 holpful if he could have answers to the following:
What is total nunber of TMI-2 pressurizer heater rods?
What is the total mass of the TMI-2 pressurizer heater rods?
What is the heat input of each THI-2 hester 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 af ter I was contacted by Mr. P. Shewmanski of the Plant Systems Branch of DOR who seemed to be interested generally in the same tyEe of information as Mr. Sheron.
I told h,ig,3 hat I would inform hira of anything I could learn with w to the pressurizer, hecdec, 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 information regarding the pressure capability of the TMt-2 reactor coolant peup. The attached hand writteis notes contain more detailed, data, but the basic message conveyed by B5W was that at about 3300 psi system pressure the puno upper bearing would probably overheat. The pump is equipped with three full systen pressure seals and cocplete failure of all three would not be expected before aoout 4700 psi. daw committed to provide ce with the balance of the information by phone at home later in the evening.
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M MAY 21979 File 3-J. Knight telepnened tne reactor coolant pump information inmediately to F. Scnroeder at the IRC usinq the speaker phone with myself anc R. 80snak cresent.
Mr. Knient also pointed out to Mr. Schroeder that the pressurizer code safet/
valves would lif t at 2500 psi and should prevent pressurizer pressure from going ruch higher if that was a concern.
Mr. Knight informed F. Schroeder that I would phone the ansvers to the rest of his questions to him at the IRC af ter '
B&W called me later that evening.
M.
At 7:05 p1, 83W (O. Mars,d Burnet, J. Hitchum, end F. Rains) phoned me at heae. The following information was provided:
- 1) The THI-2 oressurizer heater rods were designed to operate Tubnerged in water. 34W has no data as to how the roos wo;1d perforn in a superheated or saturated stean environment.
The rods have been tested in air and lost about two ninutes uncovered. B&W estimates that in a steais environnent their life expectance would prcbably be less than in air.
B&W estimated that at some lower than full electrical inout the heaters would probably function indefinitely, but they had not determined what that input was. They asked me if I though they should cetermine it, and noted it would require a fairly larqe c-u 2"- "1 campsf aa,ocal ef fort to do so. I reouested that they do so and phone the response to re on the norning of 4-5-79.
- 2) As far as the " weakest" portions of the Dresstirirer fnr pressure loading was concerncd, RAW advisec that the gasket sealing the manway access cover near the top of the vessel would fall first fraa high pressure followed by the seal welds of the heater rods to the vessel penetrations. They acvised that they were calculating the exact failure pressures and would -
' : ' m for ug ce of their values on April 5,1979.
- 7) With regard to the pressurizer heater neerical and functional data that fir. Sheron and Mr. Shewmanski were interested in, I was informed as follows:
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g MAY 21979 File a) Each heater rod has an electical output of 14 KW.
b)
There are 39 heaters in each bundle.
c) The total heater cutput 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.
Inmediately after the B&W call I telephoned F. Schroeder at the IRC and gave him the infortation per items 1 and 2 above which he had requested.
I noted that B/.V was going to try to deternire at what reduced power input the pressurizer heaters cousd coerate uncovered indefinitely, but based on our discussion I had the impression that obtaining this information was not a high priority item at the IRC.
The next morning I conveyed the information on the heater rods per item 3 above to both Mr. Sheron and Mr. Shewmanski.
After conveying this f 7 formation, either Mr. Sheron, Mr.
Shewmanski or both, I cannot recall at this writing and ny notes do not indicate, but in any event, discussions with both indicated a need for the following additional clarifications and information 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 paraceters are being neasured in the reactor coolant system for cycling the heaters on an off?
a.!r t un.. ^
beli og L6ter in the day B&W called me back 02. and D. Mars, I tcts) with the following responses:
Each pressurizer heater bundle of 13 rods weighs 897 lb.
Tne diaceter of each rod is 0.660 plus or minus 0.005 inches.
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4-MAY 2 1979 File 5-The heater rods are installed on a triangular pitch of 2.375 incnes center tn center.
During normal plant operation the pressurizer heaters cycle on and off in response to pressure neasurements only.
Electrically speaking the thr 9 groups of heater rods are wired into four banks as folloi 1:
BK #1 - 126 KW capacity cycles on at 2135 psi ano 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.
McFadden of B&W with the following information regarding the failure pressures for pressurizer vessel components:
Manway Cover Gasket - 3500 ps1 Seal Welds on Heater Rods - Significantly higher but rot quantified.
I queried Mr. McFadden about the status of the determination of the reduced power input at which the pressurizer heaters could be operated at indefinitely a stean anvironment.
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 thea back and expressly requested they proceed with the determination.
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.s MAY 2 1979 File 6-This last pressurizer information I deciced not to transnit to the IRC because it seemed irrelevant in view of the pressurizer safety valve set-point of 2509 psi and tne Reactor Coolant Pump bearing overheat pressure which was more limiting at 3300 psi.
F. C. Cherny, Section Leader
. Mechanical Enaineering Branch Division of Systens Safety cc w/att:
D. Crutchfield, NRR cc w/o att:
F. Schroeder, DSS J. Knight, 053 R. Bosnak, DSS B. Sheron, DSS P. Shemanski, DDR
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