ML20112G254

Forwards Topical Rept on Exams of Portions of Reactor Bldg Spray Sys Piping from Arkansas Nuclear Plant 1. Leaks Due to IGSCC on Inside of Piping Caused by Chloride Ion.Source Unknown.Item Could Pose Generic Problem

ML20112G254
Person / Time
Site:	Arkansas Nuclear, 05000000
Issue date:	02/07/1975
From:	Berry W Battelle Memorial Institute, COLUMBUS LABORATORIES
To:	Seyfrit K US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20105C070	List: ML20112G254 ML20112G277
References
FOIA-84-316 NUDOCS 8501160263
Download: ML20112G254 (2)

Text

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@Ballelle Columbus Laboratories 505 Kmg Avenue Columbus, Ohio 43201 Telephone (614) 299-3151 Teles 24 5454 February 7, 1975 e )

Dr. Karl B. Seyfirt Regulatory Operations United States Atomic Energy Commission Washington, D.C. 20545 gjpp

Dear Dr. Seyfirt:

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The attached report presents the results of our examination of a portion of cracked welds in the 10-inch Type 304 stainicas steel piping from the recircuir?ing line of the Reactor Building Spray System in the Arkansas Nuclear Plant No. 1.

This research has been conducted in cooperation with Dr. J. B. Henderson of your staff and Mr. Alan R. Herdt of Region II in Atlanta.

The results indicate that the leaks were the result of intergranular stress-corrosion cracking that initiated on the inside of the piping and propagated along the outside edge of the sensitized heat-affected zone adjacent to the veld. Chemical analyses of several surfaces indicate that the probable cor-rodent was chloride ion. The probable source of stress was excessive residual stress from weld repairs or high heat input during, welding.

The source of the chloride ion is not known definitely. Construction and operation history and circumstantial evidence do not indicate any evidence of gross contamination by chlorides. At this time, it appears that the low levels of chloride in the boric acid solution in the pipe (<0.1 ppm) may have become concentrated by ion exchange in the oxide tarnish film on the heat-affected zone of the piping. There is precedence for this chloride-ion concentration mechanism, as well as for the stress-corrosion cracking of sensitized stainless steel in boric acid contaminated with small amounts (ppm) of chloride.

Unless additional information is forthcoming on sources of chloride ions, it appears that cracking of this nature could be a generic problem wherever there are high residual tensile stresses adjacent to welds. It would be impossible to assure zero chloride content in the boric acid solution and very difficult to remove the tarnish films produced on the inner surface of the pipe during welding. We would be pleased to conduct a limited study to determine whether this is a generic problem. We would welcome the oppor-tunity to discuss our approach, which includes both dead weight loading and constant strain rate stress-corrosion tests.

8501160263 840625 y-PDR FOIA BELL 84-316 PDR s

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. e Dr. Karl B. Seyfire 2 February 7, 1975 Please contact me if you have any questions concerning the results of our examination.

Very truly yours, M

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u vai Warren E. Berry Associate Manager Corrosion and Electrochemical Technology Section WEB nkd Enc. (25) ~

cc: Mr. Alan R. Herdt U.S. Atomic Energy Commission Directorate of Regulatory Operations Region II - Suite 818 230 Peachtree Street, N.W.

Atlanta, Ceorgia 30303 Enc. (5) cc: Mr. H. N. Miller Contracts Division Chicago Operations Office U.S. Atomic Energy Commission 9800 South Cass Avenue Chicago, Illinois 60439 Airmail 5

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