si5 ¢ 
Magnitude of the Waste Problem - A Hypothetical Reactor. 
To define the magnitude of the waste problem, let us consider a 
reactor in which the following occurs: Enriched uranium fuel is used 
in a reactor designed to produce 1000 megawatts of heat. If the specific 
ZS) 
as in the Materials 
239 te 
the reactor is operated until 30% of the fuel is consumed, the quantity of 
235 
U 
power is approximately 10 kilowatts per gram of U 
Testing Reactor, the reactor would have to contain 1000 kg of U 
fission products produced is approximately 254 grams per kilogram of 
initially charged to the reactor. If the fuel is allowed to decay fer 
approximately +ee@-deys after discharge from the reactor, the specific 
fission products shown in Tables 3 and } will be present per 1000 grams 
charged to the reactor. Table 3 lists those fission products with half 
lives less than 1 year; Table 4 those with half lives greater than one 
year. 
In the tables curies are listed as beta curies and gamma curies 
merely to distinguish between beta emissions and gamma emissions. Barium 
140 has a fission yield of approximately 6% and dictates shielding at 
short cooling times. Lanthanum, its decay daughter emits a 2.1 mev gamma, 
the most energetic of active fission products which exist after short 
cooling. This y photon controls shielding at about 60 days cooling. 
With continued operation of nuclear reactors the longer half lived isotopes 
cst37 sr? pelt and met? will build up to large equilibrium concentrations 
as reactor irradiation is continued. Similarly, because of their long 
half lives, they will be the principle activities that reach large equilibrium 
quantities for storage or disposal as radioactive wastes. 
DECLASSIFIED 
