ML20238E387

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Confirms Points Discussed in Telcon.Study Conducted at Univ of Michigan to Characterize Effects of Radiation on Shrinkage in Boraflex Used Boraflex Produced W/Same Procedures as Used in Plants
ML20238E387
Person / Time
Site: Quad Cities  Constellation icon.png
Issue date: 08/26/1987
From: James Anderson
BISCO PRODUCTS, INC.
To: Hodge C
Office of Nuclear Reactor Regulation
Shared Package
ML20238E264 List:
References
NUDOCS 8709140313
Download: ML20238E387 (3)


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bisco August 26, 1987 bisco products, Inc.

1420 renaissance drive park ridge, Illinois 60068 (312)2984200 telex 282482 brand prid Dr. C. Vernon Hodge '

Generic Communications Branch Division of Operational Events Assessment Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, DC 20555

Dear Dr. Hodge:

This letter will serve to confirm several of the points covered in our recent conversation.

A study was initiated some time ago at the University of Michigan to characterize the effects of radiation on shrinkage in Boraflex. A preliminary report was issued which presented data through a cumulative dose of 1E10 rads gamma and greater than 3E18 neutrons /cm2. The Boraflex used in the test was produced under the same production procedures and raw material specifica-tions which apply to that material used in Turkey Pcint and other spent fuel storage racks.

The data collected indicates the shrinkage at both the SE9 and 1E10 levels of irradiation was essentially the same, averaging in all dimensions 2.1% with a length to width swing of about

+/-0.2%. Preliminary evaluation of the 2.5E10 data shows an average of about 2.4% with a length to width swing of about 0.4%.

The cause of the swing is being evaluated, but could be caused by some anisotropy or by increasing measurement error coincident with a small observed loss of sharpness of the edge. The relatively small sample size causes a measurement of only 0.01 inches to represent about 0.6% size change, therefore, it would be expected that the measured shrinkage would err on the high side as the sharpness of the sample edge declines.

Since the accuracy factor is a significant limitation of small size samples, we recommend that test coupons be as large as possible. Disco has entered into a new agreement with the University of Missouri in which samples measuring about 5" x 12" will be irradiated in order to minimize the measurement accuracy factor. In addition, since the reduction of edge sharp-ness in the high dose samples range from less than .01 inches to about .04 inches, the larger sample will essentially eliminate this affect from the determination of shrinkage.

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Dr. C. Vernon Hodge August 26, 1987 Page 2.

As usual, we will keep you informed of future data as it is generated. .

Sincerely,

/4. .

VJames S. Anderson h President JSA:lfh -

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