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MAY 19 '97 a5:27PM ISOMEDIX CORPORATE P.c^/6 <br /> ~SOtNiEOr3c , _ ~ <br /> '~7 ~i~Y 19 P(`l 2 15 May 19, 1997 <br /> - ~ CCUNY :.~L~ " <br /> Ms. Margarita Hopkins COUNTY CF HAWAII <br /> County of Hawaii ° <br /> Department of Research and Development <br /> 25 Aupuni Street; Room 219 <br /> Hilo, Hawaii 96720 <br /> Dear Ms. Hopkins: <br /> In reference to your letter to George Dietz dated May 16, 1997, <br /> we are pleased to provide the following responses. <br /> 1. If a piece 'of cobalt 60 is dropped in the pool, will the <br /> .water get. contaminated? If we take the piece out of the <br /> pool, is the water no longer contaminated? <br /> Cobalt 60 source material is both nickel plated and doubly <br /> encapsulated in stainless steel tubes to prevent the <br /> possibility of exposed cobalt 60 coming in contact with the <br /> water. Also, since cobalt 60 is not soluble in water, <br /> should a piece of exposed cobalt 60 get into the pool <br /> outside of its normal encapsulation, it could be easily <br /> captured using the existing water filtration system and the <br /> water would not be contaminated. <br /> Only source-encapsulation designs registered with the USNRC <br /> are approved for use in an industrial irradiator. The <br /> manufacturers of cobalt 6o sources must submit their <br /> encapsulation design along with the appropriate test data <br /> indicating compliance to the criteria listed in 10 CFR part <br /> 36.21(a)(5), attached, to ,the USNRC for approval. <br /> 2. If only 10.4 of the original energy of the cobalt 60 remains, <br /> what does this mean? Ts that IeveZ safe? Why do we sti31 <br /> have to dispose of it properly? Can we not just throw it in <br /> the ground? <br /> The half life decay of cobalt 60 is approximately 5.3 years. <br /> <br /> " Therefore, after a little more than 16 years from theme dQate <br /> of manufacture, the curie content of the cobalt 6 e <br /> is approximately 10~ of its original value. ZIl6m FND GAP <br /> g{~, Presented <br /> MAY 2 0 1997 <br /> CORPORATE OFFICES • 11 APOLLO DRIVE, WHIPPANY,' NEW JERSEY 07981 • (201)887-4700 AX~----°- <br /> <br />