ML20205H055

Advises That on 860728,util Received Two Empty IF-300 Casks W/Contamination Levels in Excess of 10CFR20.205 Limits. Possibly Caused by Cs-137 Leaching Out from External Surface

ML20205H055
Person / Time
Site:	Cooper
Issue date:	08/01/1986
From:	Horn G NEBRASKA PUBLIC POWER DISTRICT
To:	Gagliardo J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
CNSS865918, NUDOCS 8608190700
Download: ML20205H055 (2)

Text

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.. N COOPER NUCLEAR STATION Nebraska Public Power District " " "A"E" "0%5; o n""^>',"^

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CNSS865918 August 1, 1986 A(JG l 2 E N

Mr. J. E. Gagliardo, Chief Reactor Projects Branch U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Subject:

10CFR20.205. (b)(2) Notification

Dear Mr. Gagliardo:

This letter is a followup to the telephone notification made to Mr. R. Baer, USNRC Region IV Office, on July 29, 1986. As discussed with Mr. Baer, a rail shipment of two empty IF-300 casks, Serial Numbers IF-301 and IF-302, containing only residual contamination was received by Nebraska Public Power District at 1851 July 28, 1986. All shipping criteria were met with the exception of the smearable contamination readings on both casks. Nine of thirty-two readings on cask IF-301 and five of thirty-two readings on cask IF-302 were greater than the 22,000 beta and gamma dpm/100 cm 2 allowed in 10CFR20.205. Additionally, the contamination limits of 10CFR71.87 were exceeded even when using other methods of contamination assessment as allowed by 10CFR71.87. It did not appear that this contamination resulted from leakage of the radioactive contents of the cask, but rather from contamination leaching out from the cask external surfaces.

It should be noted that as the result of a recent INPO commitment, the instruments used to determine the smearable contamination readings at Cooper Nuclear Station are now calibrated with cobalt-60, rather than cesium-137.

This change was made because isotopic analysis of smearable contamination in various locations at the station indicated cobalt-60 to be the predominate isotope detected.

An isotopic analysis of the smearable contamination on the casks in question indicated that 80% of the contamination detected was cesium-137. Had a cesium-137 instrument efficiency had been used, cask IF-301 would have had four of thirty-two readings greater than 22,000 beta and gamma dpm/100 cm2 and cask IF-302 would not have had any readings in excess of any contamination limits.

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. t J. E. G:gliardo August 1, 1986 Page 2 If you have any questions regarding this letter, please contact me at the site.

Sine rely, w

G. Horn Division Manager of Nuclear Operations GRH:RLB:ya ec: L. G. Kuncl J. M. Pilant t'

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