Sec. 19.4] THE SAFE HANDLING OF RADIOACTIVE MATERIALS 455 



permanent, inert materials such as stainless steel or monel metal. Both types 

 of surface material have certain advantages that must be considered according 

 to the specific requirements of the laboratory when a choice is made. Absorb- 

 ing materials, by taking up spilled or splashed liquid, do not allow radioactive 

 dust to be readily formed. It can also be replaced at reasonable cost and 

 effort after contamination. Stainless steel can be thoroughly cleaned, if 

 necessary, with dilute acid, but it still has a tendency to allow dust to form 

 unless the most diligent efforts are taken to avoid it. If contamination 

 becomes serious, stainless steel is also expensive to replace. 



All surfaces, particularly floors, should be nonabsorbing, smooth, and as 

 free from cracks as possible. Wood floors for example are undesirable since 

 it is impossible to avoid cracks between boards in their construction, and it is 

 virtually impossible to remove subsequent contamination without replacing 

 the floor. Concrete is also undesirable since it is impossible to decontaminate 

 without removal. 



19.4. Special Laboratory Equipment. Special laboratory equipment as 

 well as procedures for handling radioactive materials must be designed 

 primarily to safeguard personnel from irradiation while manipulating any 

 pieces of apparatus containing active material. The variety and complexity 

 of handling equipment that should be made available will be found to differ 

 considerably from one laboratory to another and from time to time since the 

 amount of protection from radiation which must be afforded by such equip- 

 ment will depend upon the level of activity, the kind of radiation and, to 

 some extent, the specific requirements of the handling procedure. Thus 

 for high-intensity high-energy gamma-active materials, general shields 

 enclosing the entire operation and remote handling devices are required, 

 whereas for some isotopes that emit only soft beta particles, rubber gloves 

 and shielding in air alone may suffice. For this reason the kind of handling 

 equipment, shielding, and details of a process, however simple, should be 

 carefully planned in advance. It is obviously pointless, expensive, and 

 inefficient to employ great excesses of shielding and unnecessarily complicated 

 handling equipment and procedures when a much simpler and more direct 

 technique would provide the requisite protection. On the other hand the 

 converse situation presents a positive danger when needless risks are taken 

 to speed up work. Unfortunately there is as yet little standardization in 

 the design of handling equipment, techniques, and apparatus for working 

 with active materials, and consequently it has been the practice for each 

 laboratory to prepare the instruments and shielding that its particular iso- 

 topes and processes require. Whatever the activity level and kind of 

 radiation, however, the safest practice is that which always limits personnel 

 exposure to little more than the normal background rate for cosmic radiations 

 and other natural radiations. 



