ML20126B784

Submits Daily Highlight.On 840207,NRC Met W/Util to Learn Results of Util Investigation Into Steam Generator Problem & to Learn Util Proposed Repair Method

ML20126B784
Person / Time
Site:	Three Mile Island
Issue date:	04/08/1982
From:	Jacobs R Office of Nuclear Reactor Regulation
To:	Carter J, Harold Denton, Eisenhut D NRC
Shared Package
ML20126B295	List: 05000289/LER-1981-013, Forwards LER 81-013/01T-0 Re Leaking Found in Steam Generators.Event Reportable Per Tech Spec 6.9.2.A(3). Supporting Documentation Encl IA-84-897, Forwards Safety Evaluation Re Increase in once-through Steam Generator Primary to Secondary Leakage Rate,Per NUREG-1019 & Suppl 1.Rate Acceptable ML20126B293 ML20126B302 ML20126B316 ML20126B321 ML20126B337 ML20126B342 ML20126B358 ML20126B376 ML20126B390 ML20126B412 ML20126B435 ML20126B467 ML20126B475 ML20126B493 ML20126B504 ML20126B513 ML20126B520 ML20126B560 ML20126B563 ML20126B585 ML20126B592 ML20126B610 ML20126B618 ML20126B623 ML20126B635 ML20126B639 ML20126B648 ML20126B650 ML20126B656 ML20126B658 ML20126B667 ML20126B670 ML20126B684 ML20126B688 ML20126B701 ML20126B708 ML20126B716 ML20126B719 ML20126B739 ML20126B751 ML20126B758 ML20126B766 ML20126B784 ML20126B797 ML20126B806 ML20126B825 ML20126B831 ML20126B879 ... further results
References
FOIA-84-897 NUDOCS 8506140213
Download: ML20126B784 (2)

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30,, UNITED STATES a NUCLEAR REGULATORY COMMISSION 3 I wAsHmGTON, D. C. 20666 . .

April 8,1982

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Docket No. 50- 289 I MEMORANDUM FOR: H. Denton S. Hanauer 4g ~ l191+

J. Carter R. Vollmer D. Eisenhut R. Mattson R. Purple H. Thompson I T Novak J. Sniez A G. Lainas c . topolito J R Tedesco C. Michelson C. Heltemes THRU: John F. Stolz, Chief, Operating Reactors Branch #4, Division of Licensing I:

! FROM: Richard H. Jacobs, Project Manager Operating Reactors Branch #4, Division of Licensing

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SUBJECT:

DAILY HIGHLIGHT 9

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Three Mile Island Unit 1 (TMI-1) Steam Generator Repairs l The staff met with GPU yesterday to learn the results of GPU's investigation into the TMI-1 steam generator problem and to learn GPU's proposed repair method. The tube corrosion mechanism is stress assisted intergranular attack initiated from the primary side resulting in the development of I circumferential intergranular cracks. It is estimated that approximately i 8-10,000 out of 31,000 tubes in both steam generators are affected. All but about 70 defects are located within the upper tubesheet region of the

! tubes. The chemical agent which caused the attack was sulfur in a 4

reduced form.

i GPU announced that they plan to repair the defective tubes by expanding and resealing the tube walls at a location about 8-10 inches within the 24 inch tubesheet. The tubes would be either hydraulically, mechanically or explosively expanded and then rolled to create a pressure boundary seal .

By this method, the tube portion containing the vast majority of the defects is no longer a primary to secondary pressure boundary. The approximately 500 tubes with defects below the 10 inch level will .be plugged. Assuming this repair method is acceptable, GPU could repair the steam generators and make the plant ready for operation by about October 1982. <

! Because the corrosive attack was primary side initiated', GPU intends to l

conduct a comprehensive examination of susceptible materials in the reactor vesseland other parts of the reactor coolant system. The inspection of reactor vessel internals is scheduled to begin following vessel head removal early next week. The inspection involves radiographic, ultrasonic, penetrant and visual inspection techniques of a large number of components. At least two fuel assemblies will be removed to facilitate the inspection.

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'-1 Daily Highlight -

il 8,1982 .

GPU issued the attached press release yesterday which provides addit!onal details of the repair technique and the source of the sulfur contamination.

Richard H. Ja obs, Project M'anager Operating ctors Branch #4 l Division of Licensing 1

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Attachment:

, GPU Press Release l cc w/attachmentf l

JStolz RJacobs ORBf4 Files l

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