RADIOACTIVE BARIUM-140

Press, Volume CI, Issue 29871, 11 July 1962, Page 12

RADIOACTIVE BARIUM-140

High Fall-Out

In Mav

Fall-out of radioactive barium-140 measured bv the Institute of Nuclear Sciences in rain which fell in the Hutt Valley in May was 1000 times treated than the institute had ever found since it started look’ng fa- the isotone in May. 1959. the director of the institute (Mr T A Rafter) said yesterdav The fall-out was from the current American test serices as barium-VO is a short-lived isotope with a half-life of on’v 12.8 days, he said. There was no means of comparison with the amount of barium-140 received at (tracefield as a result of the 1958 test series, as the isotope’s rapid rate of decay meant it would almost certainly have fallen below the level of detectability before May. 1959 No barium-140 was detected from last year s Russian test series. No increase in strontium-90 deposition had so far been observed through the current American test series, said Mr Rafter.

The only previous time that barium-140 had been susoected in checks at Gracefield had been after the French Sahara tests of April 1960 When the Russians started testing again, in September last year, barium-140 was sought but although the checks were carried oh for four months no positive identification was obtained “With the much closer American testing-grounds, when Amedican testing resumed on April 25. 1932. it was anticipated that barium--140 would be identified." Mr Rafter said “This proved true, for the rain falling over Craceficld for the month of May gave a barium-140 response 1000 greater than any nrevious measurement

“While this barium-140 response was so definite however, of the strontium-99 reaching New Zealand only about 10 per cent could be attributed to the recent American tests