241Am and238,239(240)Pu concentrations have been determined in soil samples from the Atolls of Mururoa and Fagataufa as well as from Palomares
for comparison. Mean activity ratios of241Am/239(240)Pu for Mururoa, Fangataufa and Palomares with 0.017±0.005, 0.050±0.012 and 0.25±0.07 respectively, show, that also in the
most unfavorable case the241Am contamination remains less than about one third of the239(240)Pu level. The estimated isotopic composition of the different types of weapons-grade Pu based on these data suggests generally
a much lower241Pu/239(240)Pu ratio for Pu used in the first fisson bombs than for the material taken later on for construction of thermonuclear devies.241Pu/239(240)Pu activity ratios of 0.9±0.2 have been found at the safety shot area of the Colette motu and 8.4±0.8 at Palomares, with some
hints to a lower one, viz. 5.7±1.5 for at least one of the accidentally involved bombs.