Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Tsujimura, Norio
Radioisotopes, 69(8), p.253 - 261, 2020/08
The Japan Coast Guard observation vessel Takuyo encountered nuclear fallout originating from a U.S. nuclear weapon test detonated at Bikini Atoll on July 12, 1958. The exposure occurred two days after the detonation when the vessel was sailing southbound, about 300 km west of the danger area set up around the test site. From a small amount of rain sampled at the beginning of a rainsquall, a gross beta radioactivity of 16 kBq/L was observed, but no total precipitation measurement was made at that time. Therefore, the total amount of gross beta activity surface deposition density was alternatively derived based on an indication of a NaI(Tl) scintillation detector placed 0.3-m above the after deck of the Takuyo. By combining the maximum measured dose rate of 3.1 
Sv/h aboard with the results of Monte Carlo simulations, the surface deposition density on the Takuyo was estimated to be 2 PBq/km
, about 10 times higher than the past maximum observed in Japan in 1966. The resultant effective dose to crew members was also estimated to be below 100 Sv over the entire period of the voyage.
Tsujimura, Norio
Isotope News, (768), p.38 - 39, 2020/04
no abstracts in English
Tsujimura, Norio
Isotope News, (763), p.42 - 43, 2019/06
no abstracts in English
Tsujimura, Norio
Hoken Butsuri (Internet), 54(1), p.40 - 44, 2019/03
Rainwater containing radioactive materials originating from the USA's nuclear weapon test conducted at Bikini Atoll was observed throughout Japan in 1954. It has been reported that the maximum gross beta activity observed at that time in Kyoto was 523 pCi/mL (19,000 Bq/L). This measurement, however, focused on the gross beta activity contained in a small amount of rain sampled at the beginning of rainfall, which is different from present observations that are based on the average gross beta activity contained in rain collected during a 24-h period. As a result of reviewing and converting the 1954 data to be equivalent to current measurement, the maximum value was reduced to 50 pCi/mL (1,800 Bq/L), with a resultant surface deposition density of 310 mCi/km (11,000 MBq/km). These values are well below 1/10 of the past maximum observed a few days after China's fifth nuclear weapon test in 1966.
Tsujimura, Norio
no journal, ,
no abstracts in English
