TABLE 1 SOURCE SPECTRA USED FOR 7°°u and 7°? Th EXPOSURE RATE CALCULATIONS Source Energy (Mev) ~ 24 .29 ~35 -49 - 61 ~77 . 94 1.12 1.24 1.39 1.58 1.76 2.20 2.44 23% uy Series Source Photons per Energy Disintegration (MeV) -1l . 24 .38 . 08 242 -1ll . 04 _19 . 08 . 09 . 06 .21 . 08 . 02 -16 - 24 . 33 .44 .51 .58 73 . 92 1.60 1.80 2.62 22 222th Series Photons per Disintegration -12 . 80 _19 .05 .09 .30 .10 -56 - 28 ~ OL -35