A preliminary study on the use of 10Be in forensic radioecology of nuclear explosion sites

Cosmogenic 10Be, known for use in dating studies, unexpectedly is also produced in nuclear explosions with an atom yield almost comparable to (e.g.) 137Cs. There are major production routes via 13C(n, α)10Be, from carbon dioxide in the air and the organic explosives, possibly from other bomb components and to a minor extent from the direct fission reaction. Although the detailed bomb components are speculative, carbon was certainly present in the explosives and an order of magnitude calculation is possible. The (n, α) cross-section was determined by irradiating graphite in a nuclear reactor, and the resulting 10Be estimated by Accelerator Mass Spectrometry (AMS) giving a cross-section of 34.5 ± 0.7 mb (6–9.3 MeV), within error of previous work. 10Be should have applications in forensic radioecology. Historical environmental samples from Hiroshima, and Semipalatinsk (Kazakhstan) showed two to threefold 10Be excesses compared with the background cosmogenic levels. A sample from Lake Chagan (a Soviet nuclear cratering experiment) contained more 10Be than previously reported soils. 10Be may be useful for measuring the fast neutron dose near the Hiroshima bomb hypocenter at neutron energies double those previously available.