17 



ACTIVITY LEVELS IN RELATION TO 

 LABORATORY DESIGN AND PRACTICE 



A. R. W. Wilson 



Australian Atomic Energy Commission Research Establishment, 

 Lucas Heights, N.S. W. 



INTRODUCTION 



In planning an experiment involving radio-active material, proper con- 

 sideration must be given to the measures, appropriate to the amount and 

 radio-toxicity of the nucleide involved, which should be adopted as protection 

 against the hazards of ingestion and inhalation. Particular consideration 

 must be paid to the type and finish of the laboratory building and the 

 requisite degree of containment of the experiment, i.e., can it be carried out 

 in the open laboratory, or should it be contained inside a fume hood or 

 glove box? It must further be decided whether special measures are required 

 to control the spread of radio-active contamination. 



The question of laboratory design and standard has been considered in 

 detail by various authors^-". Dunster^ in particular, has classified labora- 

 tories into three general standards of finish, and has tabulated the amounts 

 of activity which may reasonably be handled in each. Considerably less 

 guidance is, however, available on the requisite degree of containment and 

 the necessity for contamination control measures. It is, of course, not possible 

 to lay down any rigid rules concerning these, since a number of parameters 

 which determine the degree of hazard, cannot be evaluated except as a 

 result of experience, and then only as lying within a relatively broad range. 

 Typical of such parameters is, for instance, the mass fraction of a powder 

 sample which might become airborne in the course of a weighing operation. 

 This will depend, inter alia, on the density and particle size distribution of the 

 powder, the draught across the sample, and most importantly, on the skill 

 and care of the worker. 



Despite these difficulties, and allowing for the probability that early 

 estimates may prove to be a long way wide of the mark, it does appear 

 useful, in setting up a laboratory for work with radio-active material, to 

 attempt to form some guiding rules which can be amended in the light of sub- 

 sequent experience. Whilst it is clearly important that any such rules should 

 not under-estimate the control precautions required, it is also most desirable 

 that over-elaborate precautions should not be adopted, since this would not 

 only lead to a wasteful use of expensive facilities but, moreover, appreciably 

 restrict the methods which can be used to carry out the experiment. 



HAZARD classification OF AREAS 



The activity levels discussed in this paper have been calculated for initial 

 application at the Lucas Heights Establishment of the Australian Atomic 



147 



