137. 



have a short half-life, so that radioactivity and heat are both largely- 

 reduced. However, other fission products, such as Cs-137, with a 

 half-life of 33 years and Sr-90, with a half-life of 25 years, are still 

 present in the waste in important quantities after months of storage. ( ' 



13.5 The transportation of such wastes to cooling tanks and its storage 

 in such tanks , whether earth or metal, requires the exercise of much 

 precaution. The piping and other vessels used in transportation must 

 be chemically resistant to corrosion and the stainless steels and other 

 metals required are costly. The building of metal tanks or the excava- 

 tion of earth reservoirs for storage during the cooling period is also 



a serious economic burden. These costs must be balanced against 

 costs of shielding and handling required to transport the waste to sites 

 of disposal. It, therefore, becomes a problem in economics as to how 

 long it is feasible to hold such wastes in temporary storage to reduce 

 their activity before ultimate disposal. The engineering problems re- 

 lated to the transportation and storage during the cooling period have 

 been solved but at high unit cost. 



13.6 Perhaps the most difficult engineering problem connected with 

 the underground storage of high-level waste is that of heating. The 

 energy released from such waste as heat is, depending upon concentra- 

 tion, expected to be from 1 to 3 Btu per hour per gallon. An acre -foot 

 of such waste would, at the higher figure, produce about 1,000,000 

 Btu's per hour, equivalent to the combustion of about 700 lbs. of coal. 

 From the standpoint of usable power, this is low-level heat and below 

 the level of economic utilization. But, from the viewpoint of disposal, 

 this amount of heat creates a problem that would be continuing for a 

 period of 20-30 years. 



13.7 It is feasible to excavate in underground salt deposits reservoirs 

 that are adequate to contain the volumes of liquid waste that are con- 

 templated in a program of development of nuclear power. However, the 

 waste stored in such reservoirs would soon, from its own energy, rise 

 in temperature to the boiling point, creating an additional hazard of 

 production of radioactive vapor. The holding of the temperature in such 

 underground reservoirs below the boiling point would require the re- 

 moval of the heat by a cooling system installed in the reservoirs. The 

 maintenance and operation of such a system presents problems of engi- 

 neering design which, in themselves, appear to be manageable but only 

 with substantial installation, maintenance and operating costs. An al- 

 ternative method would be to let the temperature of the tanks exceed the 

 boiling point and remove the heated air and vapor by a circulating sys- 

 tem, filtering, and discharging the gases to the atmosphere. The 



