16 

 FALL-OUT MEASUREMENTS IN AUSTRALIA 



L. J. DwYER,* J. H. MARTiNf and E. W. TittertonJ 



The Australian Atomic Weapons Tests Safety Committee 



It has been the role of the AustraHan Atomic Weapons Tests Safety Com- 

 mittee to ensure that the testing of nuclear weapons in Australia does not 

 lead to damage to life or property on this continent. To provide the Com- 

 mittee with the necessary data to carry out this task, a number of special 

 projects have been instituted, of primary importance amongst which is the 

 establishment of an extensive fall-out monitoring network and a scientific 

 centi'e for the careful evaluation and prediction of meteorological conditions 

 throughout Australia, and particularly at the test site, during a test series. 

 This latter service has enabled the Committee to ascertain that conditions 

 suitable for a safe firing have been chosen. It is not our intention in this 

 paper, however, to discuss the meteorological aspects of weapon testing in 

 Australia; the phenomonology of explosions and the meteorological problems 

 peculiar to the testing range at Maralinga, in South Australia, have already 

 been discussed^-'-. We are here concerned with the measurements of 

 fall-out from our own tests and from those conducted overseas. 



The fall-out monitoring network has operated continuously since May 

 1956. Following a local test the information aflTorded by the network allows 

 us to confirm that the radio-active material reaching the ground conforms 

 to the predicted pattern, while in the periods between testing operations 

 data are furnished on the fall-out from tests conducted elsewhere. 



Other programmes, instituted to support these measurements of total 

 fission-products, examine a number of materials for particular radio-isotopes 

 occurring in fall-out and also arising from the fission of heavy nuclei. Due to 

 a combination of properties such as biological and chemical behaviour, 

 radio-active half-life and fission yield, these radio-isotopes could be con- 

 sidered to constitute a hazard under extreme circumstances. With a view 

 to assessing these hazards as they are related to fall-out over Australia, the 

 thyroids of sheep grazing close to test sites have been examined for radio- 

 iodine shortly after each test in Australia, and a wide-scale programme 

 entailing the collection of a number of biological and geophysical materials 

 and their analysis for ^"Sr is now in progress. 



With the exception of the period of the most recent test series, Operation 

 'Antler', September to October, 1957, the results of fall-out measurements 

 conducted by the network, from its inception prior to the Monte Bello 

 Islands tests. May to June 1956, up to December 31, 1957, have been 

 reported^' -• ^' ■*. The details of the gummed film, air sampling, and 



* Commonwealth Bureau of Mett-orology, Melbourne. 



t Department of Physics, Cancer Institute Board of Victoria, Cancer Institute, Melbourne. 



X Department of Nuclear Physics, .'Vustralian National Uni\ersity, Canberra. 



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