Speaker
Description
Isotopic ratios of radioactive releases into the environment are useful signatures for contamination source identification. The atomic 233U / 236U ratio analysed in representative environmental samples by Accelerator Mass Spectrometry showed ratios of (0.1-3.7)·10-2. The ratios detected in compartments of the environment affected by releases of nuclear power production or by weapons fallout differ by one order of magnitude. Significant amounts of 233U were only released in nuclear weapons fallout, either produced by fast neutron capture on 235U or directly by 233U fuelled devices. This makes the 233U / 236U ratio a promising new fingerprint for radioactive emissions, which may serve as a superior oceanographic tracer as Uranium behaves conservatively in sea water. Our findings indicate a higher release of 233U before the maximum of global fallout in 1963, setting constraints on the design of the nuclear weapons employed.
