STRONTIUM 90 AND CESIUM 137 IN FALLOUT DEPOSITS AND IMPLICATIONS OF THEIR RATIO
Radioactivity in monthly fall-out, which had been collected by the pot method, was measured for Sr/sup 90/ since October 1956 and Cs/sup 137/ since August 1957. Total accumulated amount up to July 1960 was 15 mc/km/sup 2/ for Sr/ sup 90/ and 31 mc/km/sup 2/ for Cs/sup 137/. Distinct spring maxima of fall-out rate was observed on May 1959 and 1960. Ratio of the total activities of Cs/sup 137/ and Sr/sup 90/ since August 1957 were 2.8, which is higher than the assumed ratio from nuclear fission processes, and ratio Cs/sup 137/ /Sr/sup 90/ vary considerably from month to month (1.8 to 8.2). The high observed ratio can be explained mainly from the differences in the half lives of the ancestor radionuclides of Sr/sup 90/ and Cs/sup 137/,i.e., Kr/sup 90/ (33 sec) and Xe/sup 137/ (3.9 min), respectively while monthly variation of the ratios can be explained from meteorological conditions in the rain-bearing layer of troposphere. (auth)
- Research Organization:
- National Inst. of Radiological Sciences, Chiba, Japan
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-16-007761
- OSTI ID:
- 4819224
- Journal Information:
- J. Radiation Research (Japan), Journal Name: J. Radiation Research (Japan) Vol. Vol: 2: No. 1
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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