Reinvestigation of airborne Pb-210, Cs-137 and Bi-207 in Vienna (Austria) after atmospheric nuclear weapons tests

Reconstruction of atmospheric Pb-210 and Cs-137 activity concentrations occ urring in Vienna immediately after the atmospheric nuclear weapons tests sh all answer the question, whether artificial Pb-210 has been produced by fus ion devices using lead materials. If so, Bi-207 also can be expected. In 19 62, weekly average values for Pb-210 were between 0.08 +/-0.02 and 1.31 +/- 0.30 mBq/m(3), Cs-137 amounts up to 5.1 +/- 0.6 mBq/m(3). Bi-207 remains b elow the detection limit, viz. <0.5 mBq/m(3). Bimonthly averages for the pe riods 1962-1964 and 1974-1975 show (13)7Cs activity concentrations with typ ical springtitne maxima occurring together with low Pb-210 values and Bi-20 7 < 0.02 mBq/m(3). Annual averages of Pb-210 are varying between 0.27 and 0 .53 mBq/m(3), independent of whether atmospheric tests have been performed or not. Comparison of the activity ratios Bi-207/Pb-210, Bi-207/Cs-137 and Pb-210/Cs-137 With published data, leads to the conclusion that no evidence exists for a significant production of Pb-210 by nuclear explosions, neith er after the Soviet tests in 1961-1962 nor after the Chinese tests in 1973- 1976. (C) 2001 Elsevier Science Ltd. All rights reserved.