The session chairman was E. Holm (Sweden).
(i) A. Kudo (Canada)--Plutonium Mass Balance Released from the Nagasaki A-Bomb and the Applicability for Future Environmental Research. Of the 10--15 kg of Pu in this bomb:
---only 0.25% was deposited locally, based on measurements of surface soils and reservoir sediments; --about 8% fissioned; --the remaining 91.75% was injected into global fallout.
Since the detonation was at a height of 503 m, the Pu should provide a detectable signal in the global environment. Essentially this event was an experiment in global pollution. Dr Kudo has followed this up by collecting Arctic ice cores which will be analyzed for Pu isotopes. Hopefully, this will confirm that Nagasaki Pu is an ideal tracer for global pollution. (ii) K. H. Lokan (Austrafia)--Characteristics of Plutonium and Americium Contamination at the Former U,K. Atomic Weapons Test Ranges at Maralinga and Emu. Dr Lokan described the contamination from the U.K. testing at these sites. At Emu, the bulk of the contamination was injected into the stratosphere and local fallout presents no health problems. But at Maralinga, the safety system trials, which involved chemical, rather than nuclear explosions, produced extensive contamination, consisting of particulate forms of Pu, 241Am and 235U.