23 Fractionated fission product distribution for offsite fallout. For offsite fallout, remove some of the refractory phase (input data). Fractionated fission yield = FY(A) « b(A), where b(A) = 1.0 for volatile mass chains 75-90 and 101-139. b(A) = fraction of refractory elements present, f, (input data), for mass chains 92-100 and 142-180. b(A) = 0.75 + 0.25f for mass 91 0.7 + 0.3f for mass 140 0.33 + 0.67f for mass 141. The independent fission yields of the 91, 140 and 141 chains change with fission split only by small amounts under the conditions of this study; therefore, the above assumptions were made for all shots. Relative fractionated fission product distribution The decay matrix (see 4 below) was calculated by the ORIGEN computer program (RSIC79) written at Oak Ridge National Laboratory to calculate the formation and decay of radionuclides in reactor fuel elements. Results of that calculation were the number of curies of each fission product from a 1-sec run at a power level of 4.185 MW or 108 calories or 10° 6 kt or 1.43 x 10°" 17 fissions in a fuel