ML19351G562

Interim Deficiency Rept Re Instrument Tube Not Designed for Thermal Movement During Loca,Initially Reported 801229. Test Will Be Conducted to Determine If Tube Ruptures.Final Rept Expected by 810427

ML19351G562
Person / Time
Site:	Fermi
Issue date:	01/28/1981
From:	Hines E DETROIT EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
10CFR-050.55E, 10CFR-50.55E, EF2-49-877, NUDOCS 8102250232
Download: ML19351G562 (2)

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[ k viuary 28, 1981 2-49,877 FEB 2 319815  ;

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Mr. James G. Keppler, Director ron }

Region III -

U.S. Nuclear Regulatory Cwmission b jQ 799 Roosevelt Road 4 Glen Ellyn, Illinois 60137 "

Subject:

Interim Report of 10CFR50.55(e) Item on Traversing In-Core Probe System (#36) .

Dear Mr. Keppler:

On December 29, 1980, Detroit Edison's Mr. H.A. Walker, Supervisor-Construction Quality Assurance, telephoned Mr. R. Knop of the NRC -

Region III to report on a problem with Traversing In-Core Probe Systan at the Fermi 2 Site.

Engineering investigation indicates that the traversing in-core probe instrument tube design is deficient. This determination was made by Project Design and Field Engineering during the course of a review of thermal novements associated with the primary containment liner during a loss of coolant accident (IOCA) .

Description of Deficiency The instrument tube (3/8 O.D. stainless steel) connecting the isolation valve and the primary containment penetration was designed without due consideration for thermal movement during a IOCA. This tube provides part of the primary containment boundary during containment isolation.

Analysis of the thermal novements associated with the prirrary containment liner and penetration during a IOCA indicates that this tube is over stressed and may rupture thus breaching primary containnent.

Action Taken The emputer analysis performed on the instrument tubing design to determine the stress level is based on a non-linear system. Engineering judgement indicates that the instrument tube will be subjected to bending but rray not rupture. Therefore, the follow-up action is to determine, by test, if indeed the tube does rupture. The Detroit Edison Engineering Research Department will neck-up the existing design and perform tests based on the thermal novment associated with a IOCA. These tests will be documented to provide a basis for acceptance / verification of the existing design.

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Mr. James G. Keppler, Director - Region III January 28, 1981 k Page Two EF2-49,877 A final report is scheduled to be submitted to you by April 27, 1981.

If you have questions concerning this matter, please contact Mr. H.A.

Walker, Supervisor-Construction Quality Assurance.

Very truly yours, YM DI/ HAW /cp cc: Mr. Victor Stello, Jr., Director Office of Inspection and Enforcement Division of Reactor Inspection Programs U.S. Nuclear Regulatory Comtission Washington, D.C. 20555 Mr. Bruce Little, Resident Inspector U.S. Nuclear Regulatory Camtission Resident Inspectors Office 6450 North Dixie Highway Newport, Michigan 48166

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