512 



Accuracy of Waste Inventory Estimates 



Concern has been expressed that, since the inventories of radioactive 

 waste are not known exactly , there could be a problem. In particular, 

 WASH-734 Indicated that estimates of total radioactivity could be off by a 

 factor of 10. The fact is that we are not totally ignorant of the 

 Inventories of waste materials, and even the limited information available 

 is sufficient to permit an analysis of whether the dumping practices could 

 possibly pose a threat. 



First it should be noted that being off by a factor of 10 could mean the 

 estimate could be either high or low by that value. In any case, it will 

 be shown that from a standpoint of potential hazard to either health or 

 environment it is insignificant whether the estimate is off by a factor of 

 10 or even 100 for that matter. As previously discussed, the column of 

 water defined by the Farallon dumpsite (10^ km^) contains quantities 

 of naturally occuring radionuclides which make the radioactive waste 

 trivial in comparison, from either a radioactivity or a hazard viewpoint. 

 Table 1 lists these natural radionuclides, along with their mass, 

 radioactivity and Toxicity Index. The Toxicity Index is a simple measure 

 of potential hazard expressed as the volume of water required to dilute a 

 given quantity of a toxic or radioactive material to acceptable public 

 drinking water standards. 



Table 1 



Some Naturally Occuring Radionuclides in 



10,000 km3 of Average Seawater 



(Estimated Volume of Farallon dumpsite water column) 



Radionuclide Mass (Tons) Radioactivity (Ci) Toxity Index (m3) 



Uranium-238 10^ 3 x 103 3 x 10^ 



Radium-226 10-3 io3 1 x 10^0 



Potassium-40 5 x 10^ 3 x 10^ 3 x 10°U ) 



Total 1 X lOlO 



(a) Based on a computed dose factor for K-40 relative to K-42. 



