RADIATION SOURCES AND FACILITIES 



Among the different types of available ionizing radiations, gamma rays and 

 X-rays appear to be well suited for food irradiation, 



Also, accelerated electrons can be used directly for food irradiation if the pene- 

 tration required is of a relatively shallow depth, 3/ However, they are not included 

 in this analysis because not enough information is currently available on application 

 techniques and other technical relationships,, 



Cobalt 60 



Cobalt 60 is included as a radiation source in this study because it appears to 

 be the least costly source of gamma rays. The other nucleide radiation sources 

 considered were cesium 137 and zirconium- niobium,, 



Cobalt 60 is produced by the irradiation of cobalt in nuclear reactors,. For each 

 kilowatt of radiation -source capacity, 68,000 curies are required,, It is assumed 

 that this radioactive material will be assembled in many replaceable segments to 

 facilitate source replenishment,, 



X-Ray Machines 



Linear accelerators have the greatest potential among the electron machines for 

 X-ray production because they have higher energy electron-beam ratings than the 

 other machines, and because they can be built in larger kilowatt sizes (table 3), 

 Linear accelerators as well as the other electron machines produce accelerated 

 electrons which can be converted to X-rays by means of a suitable target,, 



Table 3 ---Present and estimated future performance characteristics of electron machines, 



1964 



tut u- Present 



Machines : 



performance 



Estimated future 

 performance 



Kw. Mev. [w. Mev 



Van de Graaff generator : 1-5 1-4 No significant change 



Resonant transformer : 5-10 1-2 25 3-5 



Dynamitron : 15-30 1-3 l/70 3-5 



Linear accelerator : 1-10 3-10 250 3-10 



Insulating core transformer (ICT) : 6-10 0.3-0.5 20-30 1.0-1.5 



: 1/60 3-0 



l/ Being developed for both electron and X-ray production. 



Sources : Preservation of Food by Low-Dose Ionizing Energy (14) and information from 

 the High Voltage Engineering Corporation and Radiation Dynamics, Inc. 



3/ The depth of electron beam penetrability expressed in terms of unit density is 

 generally recognized to be 1 centimeter/2 Mev. (million electron volts), 



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