Neutron and Gamma-Ray Doses at Hiroshima and Nagasaki

Aging Effect of 137Cs Obtained from 137Cs in the Kanto Loam Layer from the Fukushima Nuclear Power Plant Accident and in the Nishiyama Loam Layer from the Nagasaki A-bomb Explosion

“…The estimated nuclear explosion energy was 22 ± 2 kt. 24 Since the number of fissions in 1 kt is 1.45 × 10 23 , the total number of fissions from the A-bomb is calculated to be (3.19 ± 0.29)× 10 23 . 25,26 The fission yield of 137 Cs is 6.6% of a 14-MeV fast neutron; 27 therefore, the estimated amount of the produced 137 Cs is (2.1 ± 0.2)× 10 23 atoms.…”