ML19289F813

Summarizes Info Obtained from B&W Re TMI Incident,In Response to HR Denton 790424 Memo.Info Partially Withheld: Home Telephone Number (Ref FOIA Exemption 6)

ML19289F813
Person / Time
Site:	Crane
Issue date:	05/02/1979
From:	Cherny F Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 7906200037
Download: ML19289F813 (13)

Text

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File F.RCM: F. C. Chrny, Section Leader Mechanical Engineering Branch, DSS SU3]ECT: RECORD OF ACTIONS, THREE MILE ISLAND ACCIDENT

Reference:

H. Denton Memorandum of April 24, 1979 to N,RR Staff As requested by the referenced memorandum, I am herein dacumenting several requests for inforration s.hich I was requested to cbtain April 4-5,1979 frca 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. Schrceder and was asked to obtain the following informtion from Babcock and '..'ilcox 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 beccme uncovered?

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

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

Subsequently, Mr. Knight discussed these questions with R. Sosnak and myself and asked that I cbtain the information through Mr. J. Taylor of the Babceck and Wilcox facility in Lynchburg, Va. Around noon of April 4, R. Bosnak and I telephoned Mr. Taylor who was temporarily unavailable but returned our call within an haue or so. From this point on, I was the sole MEB telephone contact with B&W on these and several other rclated questions. When Mr. Taylor returned our call, he designated a Mr. Dave Mars as the person frca B&W who wold provide the requested infonnation. 233 092 90620037 7- - - - 9.7 -- u /wse

I 2 UIS File Early in the af ternoon of April 4, I s.as contacted by "r. B. Sheron of the DSS Analysis Branch relative to any information I night have about the installation and functional characteristics of the TMI-2 Pressurizer Heaters. I @c..;d Mr. Sharon the information that was in the MEB copy of the TMI-2 FSAR. I mentioned to him that I had established a telephone contact with B&W and was cbtaining infonnation about pressurizer heater service life, if uncovered and in a steam environment. He stated that for so...e parametric studies he was doing, it would be hel pful if he could have answers to the following: 4 hat is total nu-ber of TMI-2 pressurizer heater rods? '.iilat is the total mass of the TMI-2 pressurizer heater rods? Milat is the heat input of each TMI-2 heater rod? I stated that since I had alreacy established a contact with B&W regarding heater service life I would try to also obtain the additional informaticn. Shortly after I was contacted by Mr. P. Sheumar. ski of the Plant Systems Branch of DOR who scemed to be interested generally in the same type of information as Mr. Sheron. I told him that I would inform him of ar.ything I could learn with regard to the pressurizer heaters. Around mid-af ternoon of April 4, I telephoned B&W and related the additional questions to D. Mars. Late in the af ternoon of April 4, B&W called back with some information regarding the pressure capability of the TMI-2 reactor coolant pump. The attached hand written notes co lin more detailed, data, but the basic message conveyed by ssW was that at about 3300 psi system pressure the pump upper bearing would prceably overheat. The pump is equipp2d with three full system pressure seals and ccaplete f ailure of all three would not be expected before about 4700 psi. B&W com.itted to provide me with the balance of the information by phone at home later in the evening. 233 093

.'.'. AY 2 U7S File _ J. Knight telephcned the reactor coolant pump information i:u2diately to F. Schroeder at the IRC using the speaker phcne with myself and R. Bosnak present. Mr. Knight also painted out to Mr. Schroeder that the pressurizer code safety valves would lif t at 2500 psi and should prevent pressurizer pressure from going much higher if that was a concern. "r. Knight inf ormed F. Schroeder that I would phone the onr..ers to the rest of his questions to him at the IRC af ter 33W called me later that evening. At 7:05 pm, 35W (D. "ars, ". Burnet, J. Mitchum, and F. Rains) phoned ne at h:me. The follcwing information was provided: 1) The TMI-2 pressurizer heater rods were designed to operate subnerged in water. 33W has no data as to how the rcds oculd perform in a superheated or saturated steam environment. The rods have been tested in air and lost cbcut two minutes uncovered. ESW estimates that in a steam environment their life expectance would prcbably be less than in air. BSW estimated that at scme lower than full electrical input the heaters would prebdaly function indefinitely, but they had not determined what that input was. They asked me if I thought they should detennine it, and noted it would require a fairly large cc putaticnal effort to do so. I requested that they do so and phone the response to me on the nor ning 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 the vessel pe netrations. They advised that they were calculating the exact failure pressures and would inform me of their values on April 5,1979.

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

233 09t N

File IMY 2 G73 a) Each heater rod has an electical output of 14 KW. 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 neater rods is 897 lb. and each heater rod weighs 10 lb. The total mass includes support plates, etc. Irediately af ter the B&W call I telephoned F. Schroeder at the IRC and gave him the information per items 1 and 2 above which he had requested. I noted that B&W was going to try to determine at what reduced power input the pressurizer heaters could operate uncovered indefinitely, but based on cur 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 5 ith Mr. Sheron and Mr. Shemanski. After conveying this information, either Mr. Sheron, Mr. Shevaanski or both, I cannot recall at this writing and my notes 20 not indicate, but in any event, discussions with both indicated a need for the following additional clarifications and information on the pressurizer heater reds: 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,'eactor coolant system for cycling the heaters on an,off ? Later in the day B&W called me back (af ternoon and D. "ars, 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 0.005 inches. 233 095

File .AY 2 1979 The heater rods are installed on a triangular pitch of 2.375 inches center to center. During normal plant operation the prassurizer heaters cycle on and off in response to pressure acasuremants only. Electrically speaking the three groups of heater rods are wired into four banks as follows: EK #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 73 - 504 KW capacity - cycles on at 2115 psi and off at 2135 psi. BK #4 - 504 KW capacity - cycles on at 2l00 psi and off at 2130 psi. I conveyed this information to both Mr. Sheron and Mr. She'ca an sk i. 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 ccmponents: Manway Cover Gasket - 3500 psi Seal Welds on Heater Rods - Significantly higher but not quantified. I queried Mr. McFadden about the status of the determination of the reduced power input at which the pressurit:er iieaters could be operated at indefinitely a steam environment. He indicated that he did not think much progress hid been nade 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. "cFadden that I felt they should spend their time in other areas unless we called them back and expressly requested they proceed with the determination. 233 096

File YAY 2 G79 This 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 care limiting at 33D0 psi. , L.. b hM'U I F. C. Cherny, Saction der Machanical Enginearing 3 ranch Division of Systec.s Safety cc w/att: D Crutchfield, NRR cc w/o att: F. Schrceder, DSS J. Knight, DSS R. Sosnak, DSS B. Sheron, DSS P. Shecanski, DDR f

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