to a disposal area; 525 curies of Na-24; 1000 curies of Ca-45; 100 
curies of Fe-59; 100 curies of Co-60; 120 curies of Sr-90; and 1000 
curies of Cs-137. The total number of curies amounts to 2,845 well 
over the suggested yearly limit of 250 curies of Sr-90. Obviously, the 
relative hazard to man, considered in the route that might return the 
waste to him from the disposal area through marine food products, will 
be less for the mixture than for strontium-90. If the quantities of each 
of the isotopes above are multiplied by the ratio of the maximum per- 
missible sea water concentration of strontium-90 to that of the isotope, 
the sum of results assuming no containment is approximately 148 
curies. This figure, which is a more realistic measure of the potential 
hazard of the waste than the 2,845 curies, includes the effect of MPC 
values for each isotope and the concentration factors from sea water to 
marine food products. 
Why dispose at sea? 
There are two ways of handling radioactive materials to prevent 
them from becoming a hazard to man. One is by containment, which 
has as its objective the retention of the material in such a manner that 
it does not get into the human environment, at least until natural radio- 
active decay has reduced the quantity of material to below permissible 
levels. The other is by dispersal, which has as its objective the dilu- 
tion of the waste to below permissible levels before it becomes a part 
of the immediate human environment. 
Within limits, procedures can be established so that disposal into 
coastal waters can take advantage of some of the desirable features of 
both methods of handling the wastes. The advantage of containment can 
be achieved by proper canister design. Presently used canisters are 
reclaimed 55 gallon steel drums which have an expected life, so far as 
corrosion by sea water is concerned, of approximately ten years (10). 
The factor of safety introduced by ten year containment is shown 
in Table III, in which the percents of the initial activity remaining after 
ten years and the maximum permissible concentrations for drinking 
water are listed for a group of isotopes including high yield, long-lived 
fission products and the isotopes that are shipped from Oak Ridge 
National Laboratories to licensed users. 
Two features of Table III should be emphasized. First, isotopes 
having long half life, that is, relatively large amounts remaining after 
ten years, and low MPC values are those that may produce the greatest 
potential hazard to man. Second, the MPC values are drinking water 
values and we are concerned here with sea water. Although not directly 
applicable to the present problem, these MPC values will be used later 
in modified form. 
The practice of mixing contaminated materials into concrete 
which is then cast into the steel drum, provides for containment 
14 
