RADON EXTRACTION PLANTS 



77 



One gram of radium will produce 166 mc of radon daily. This amount 

 will reduce by radioactive disintegration to 138.5 mc by the end of the 

 first day and will disintegrate to 115.5 mc by the end of the second day. 

 In the meantime, more radon will have been generated and will decom- 

 pose in the same way, so that by the end of a month there will be avail- 

 able 995 mc in equilibrium with 1 gram of radium. For all practical 

 purposes this amount is taken as 1000 mc, although 60 days are required 

 for radium to come into complete equilibrium with all its disintegrative 

 products. 



A sample of the gas removed from the radium salt and concentrated 

 into a capillary tube by pressure may have a " strength " as great as 

 100 mc. Owing to its disintegration, it will fall to a strength of 83.4 mc 

 at the end of 1 day, to 69.6 mc at the end of 2 days, until at the end of 

 30 days its strength is only 0.45 mc. For its detailed change in strength 

 refer to Table 11-14. 



Radon Extraction Plants 



Radon extraction and purification plants of a semi-automatic design 

 were introduced in America by the late Professor William Duane of 

 Harvard, and subsequently modified by Failla of the Memorial Hospital, 

 New York City. 



p~H|,|-..,h 

 J Switch I — 



Lead shield 



Battery-rheostat 

 Copper gauze cylinder 



Heated chromel or tungsten wire 



Gold capillary tube 



Fig. II-8. A semi-diagrammatic representation of a radon-extraction plant. 



A typical installation may use 1 or more grams of radium bromide 

 dissolved in dilute hydrochloric acid. It is usually divided into two 

 portions of about 100 cc each and stored in 200-cc long-necked flasks. 

 The flasks are joined at the top in such a way (Fig. II-8) that the accu- 

 mulated gases can be led off through a continuous train of glass tubing 



