Radioactivity Rises From French Tests

Press, Volume CIX, Issue 32072, 21 August 1969, Page 1

Radioactivity Rises From French Tests

Environmental radioactivity in New Zealand is. still increasing under the effects of the French nuclear tests in the Pacific in 1968, but is still below the peak recorded in 1964-65, according to the quarterly report of the National Radiation Laboratory, Christchurch, issued yesterday.

Routine monitoring of fall-out in New Zealand has shown that in the first quarter of this year, and also in the two previous quarters, levels of fission products in air and rainwater increased as a result of the tests, which for the first time included the detonation of two hydrogen bombs.

“The expected decrease in levels, which had been evident during the months following the previous test series of 1966 and 1967, did not take place during the first quarter of 1969,” the report says. “This delay in the gradual reduction of the level of fission products in the air undoubtedly results from the injection of fission debris into higher altitudes when hydrogen bombs are detonated.” it says.

The average levels of fie* sion products In the air during the quarter more than doubled in Auckland, and were eight and a half times greater in Wellington and seven times greater in Christchurch than they were for 1967 and 1968. Strontium 90 in rain increased slightly during the January-March period this year, but is still only a quarter of the highest level previously recorded in the same period of 1965. Levels of strontium 89 in rain have been steadily falling since October last year, one month after the conclusion of th

tests, and by March this year were less than a tenth of the maximum recording taken since the tests.

Strontium 90 in milk increased slightly during the first quarter of this year but is still less than a half of the highest level previously recorded during July-August, 1964.

! The average level of stron- ■ tium 90 in milk last year was . less than two per cent of the i permissible level for the ' whole population. > Caesium 137 in milk also i increased slightly in the first three months of this year, > although the level is still less than a half of the highest previously recorded level in March-April, 1965. The average level of caesium 137 in milk last year was about 0.3 per cent of the permissible level for the whole population.