the procedure is repeated until 10,000 (or 100,000) trials have been made. The distribution from 100,000 trials is shown in Fig. 12. The log probability (cumulative distribution) plot for the final, doses, is shown in Fig. 13. In addition, the same input data were used with a totally different method for determining the distribution of the final dose based on the distribution of each of the model parameters [50]. In this approach, the distribution of each input parameter is expressed by a finite probability distribution (FPD), which is a discrete approximation of the continuous probability density function of the parameter. The dose, expressed as an FPD, is estimated by systematically combining the input FPDsin the dose model according to the rulesof probabilistic arithmetic and storing the results in the proper, predetermined discrete output bins. The two methodsgive very similar results. The average doses presented here and calculated using mean values for all of the parameters in the model, fall at about the 68th percentile on the distribution for both methods; that is, 68% of the population would be expected to have doses below this value. A dose equal to twice the average falls near the 88th percentile for both methods; a dose three times the average falls at or above the 96th percentile. Thus, about 68% of the population on Eneu and Enjebi would have a 30-y integral dose equivalent less than 3 and 6 rem, respectively, when 0.014 -— ~] 0.012 }—- 7 g 2 8 Probability ° 0.002 7 € 2 2 3 oO 10 f— a 1 0.01 boa Li 0.5 i l 10 po sp | 50 70 | 90 1 j 99 Cumulative probability (%) Fig. 13. Log probability plot of 30-y integral dose-equivalents with the Monte Carlo method. imported foods are available. Based on this analvsis, there ts less than a 5%chance for a person to receive a dose that is greater than three times the average dose. Summary and Conclusions ILS jg Fa ne 0 TT The maximum annual dose-equivalent rates for atolls downwind of the proving grounds, that is, Likiep, Wotho, Ujelang, Mejit, Ailuk, Taka, Jemo, and Bikar for ail exposure pathways excluding cosmic radiation are less than 6 mrem/y if the MLSC diet is used and less than 30 mrem/y even when the BNL diet is used. The only significant source of natural external background exposure in the Marshall Islands is the 3.5 wR/h or 22 mrem/y from cosmic radiation [2]. For reference, these doses can be compared with the external background doses observed in the U.S. The total external background dose in the 0.010 100 200 300 The 30-y '37Cs dose (rem) Fig. 12. Linear plot of the 20-y integral dose-equivalents from 100,000 trials. 72 pT tT 100 | 1 mrem/y for Denver, Colorado, which has a population of about 500,000 (urban population of about 1,500,000); and about 182 mrem/y for Leadville, Colorado, which has a population of about 10,000 [51]. Thus, depending on the diet, most of the atolls have estimated doses 73