island.
The impact of additiona) Pu in the terrestrial environment is
discussed in part 1.
The proposed method for disposing of Pu contaminated
soil in Cactus Crater consists of forming a soil-cement slurry and filling
the crater with the soil-cement mixture.
Dye studies 3 indicate that soluble material in crater water is
transported to the island groundwater reservoirs and t> the surrounding
marine environment.
The crater water is presently recharged both by
surface and groundwater inputs.
Once the crater is filled with the soil-
cement, the fill will be in contact with and be an integral part of the
island groundwater system.
Over a period of time any crater fill below
groundwater level will be subject to erosion and leaching.
These processes
will mobilize Pu and introduce levels to the groundwater system and
subsequently to the marine environment.
If, for example, it were possible to fill the crater with soil
containing all 10 curies of plutonium expected to be transferred to Runtt
(using no cement), the average soil concentration would be approximately
280 pCi/gm.
From available data, 3 jt can be computed that the groundwater
in contact with this sail would contain, on the average, 5.0 pCi/1 of
plutonium.
The average residence time of the groundwater at Northern
Runit is 0.2 years.
Therefore 0.5 mCi of plutonium could be expected
to be annually discharged through groundwater flow from a 10 curie crater
fill.
The quantity will slowly decrease with time since the amount leaving
follows an exponential Joss curve. Cactus Crater is approximately 2% of the
island area.
If the crater is filled with 10 curies of plutonium and
not fixed with cement, 2% of the island will contribute over 50% of the