ka | - 10 days 0.32 Mev 80 days 0,30 Mev 150 days 0.28 Mev 2 years 0.48 Mev The average energy of potassium 40 according to Marinelli, Brinkerhoff and Hine\!¥) is 0.40 Mev. We believe this to be the best approximation of the energy for mixed fission products among the available long-lived isotopes. There are losses both in the collection process and in the sample processing, These are corrected for only by the overall factor of 1.6 relating mixed fission product 6 activity found in pot samples to that found in composite gummed film samples for the same periods, This factor of 1,6 was shown to be a good average value for New York City over a period of two years in 1954 and 1955, byt goes not necessarily apply to each individual sample. Weiford‘1l) has shown the relative loss of several nuclides and has found a factor of 1.85 for the year 1958, The general formula depends on the p-l.2 1aw which is not absolutely applicable to each sample and each type of debris. On the average, however, for fallout remote from the test site, it is the best value presently available, (Later reports, such as NRDL-247 indicate an exponent of -1,.25 which is not appreciably different.) No allowance is made for fission product fractionation or for induced activities. The fractionation is probably less critical at considerable distances from the test site but radiochemical data are not available for checking this point. Most of the induced activities are of relatively short half-life and are not counted with the time lag inherent in the system. The general formula does not allow for differences in geographic distribution of the debris, (For instance the 1958 USSR polar tests did not appear in the southern hemisphere). A11 samples are treated by the same formula, The effect of this can only be shown by comparing computed Sr90 values with the few data available for measured Sr90 deposition, The general formula does not allow a time lag for the debris to reach different geograpkic areas. The inclusion of such a lag would have made the computation impossibly complex, The general formula does not allow for distribution of megaton debris between the stratosphere, troposphere and local deposition, This could have been included but would have essentially doubled the computation. This was not considered worth while since the estimates of this distribution are of doubtful validity. ° x