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therefore must be disposed of in a manner which will have a negligible impact on 

 the environment. The radioactive material exists primarily as an integral part of 

 the metal forming the reactor plant components. The radioactivity was created by 

 neutron irradiation of the iron and alloying elements in the metal components. The 

 predominant radioactive isotope present is cobalt 60, which decays by a factor of two 

 every 5.3 years. The only mechanism for release of the radioactivity to the environ- 

 ment is through corrosion of the metal. 



One alternative for disposal is to place decommissioned nuclear-powered ships in 

 long term protective storage at a shipyard. While this alternative does allow the 

 radioactive material to decay under controlled conditions without release to the 

 environment, other alternatives may be more desirable for ultimate disposal. Two 

 practical alternatives for the ultimate disposal of radioactive nuclear reactor plants 

 are under preliminary study by the Navy. One alternative is to bury the subma- 

 rine's reactor compartment which houses the defueled reactor plant at an existing 

 Federal land disposal site. The other alternative is to place the entire ship, after 

 removal of the nuclear fuel, on the deep ocean bottom at a site considered accept- 

 able for such disposal. Either of these alternatives would be carried out so as to 

 provide containment and isolation of the radioactive material in the reactor plant 

 from human activities. 



The land disposal alternative, if it were selected, would be implemented at an 

 approved Federal waste disposal site. This option would take advantage of the 

 containment provided by the submarine's reactor compartment which would form 

 an outer disposal container of high strength and durability. Furthermore, the radio- 

 activity is contained within the metal walls of the defueled reactor plant located 

 within the reactor compartment. The general approach would be for the reactor 

 compartment to be removed from the remainder of the ship and all reactor com- 

 partment openings sealed. The compartment would then be moved by barge and 

 moving equipment to an approved burial site and buried. Radiation levels associated 

 with the entire operation would meet all Department of Transportation, Environ- 

 mental Protection Agfency, and Department of Energy requirements for disposal of 

 low-level radioactivity. The potential effect on the environment from the land 

 disposal alternative is expected to be extremely low and only a small fraction of 

 normal background radiation exposure. Land area use would be small. This alterna- 

 tive would be in compliance with existing regulations, for radioactive waste ship- 

 ment and disposal, and no new regulations would be required. 



The second alternative under preliminary study for ultimate disposal is to place 

 the entire submarine at a site in a deep part of the ocean where there is virtually 

 no likelihood of its being disturbed by human activities, seismic action, or ocean 

 movement. There is little biological activity in the deep oceans. The currents near 

 the sea floor of such a site would be very low, and the sea floor itself would be very 

 stable if the area is sufficiently deep and remote from the known locations of 

 seismic and volcanic instability. Previous research in the deep oceans has identified 

 the existence of several such areas that have little potential for other activities 

 useful to humans. The concept would be to tow the defueled ship to a selected 

 disposal site, flood it, and place it on the ocean floor. Preliminary information 

 indicates that the submarine would be intact after landing on the bottom and that 

 the reactor plant and containment would remain intact. Corrosion of the metal of 

 the hull and the reactor plant would then be the only way that the radioactivity 

 would be released. "This is a very slow process because of the low temperature at 

 great ocean depths and the use of corrosion-resistant metals in key parts of the 

 reactor plant. During the time required for the corrosion process, a significant 

 reduction in the radioactivity would result because of normal radioactive decay. For 

 example, in 50 years the total cobalt 60 radioactivity in the reactor plant would be 

 reduced by a factor of about 1000. 



The potential disposal site would be determined in conjunction with the U.S. 

 Environmental Protection Agency, complying with requirements established by that 

 I agency in consideration of U.S. and international laws and treaties. Studies of ocean 

 geophysics, chemistry, currents, and biology are being conducted to describe the 

 ; characteristics of the deep ocean which would provide maximum isolation and to 

 j develop information on methods for predicting the behavior of materials in the deep 

 I oceans. 



The Navy has spent appproximately one million dollars to date in research to 

 explore important factors related to the possible disposal at sea option. Most of the 

 expenditures have been for oceanographic surveys of several general deep ocean 

 areas to determine characteristics which would affect the prediction of effects on 

 humans or the environment and verification of corrosion characteristics in such 

 areas. It is expected that approximately one million dollars more may be needed to 

 complete this research. 



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