Airborne Plutonium and Non-Natural Uranium from the Fukushima DNPP Found at 120 km Distance a Few Days after Reactor Hydrogen Explosions

Abstract

Plutonium (Pu) and non-natural uranium (U) originating from the Fukushima Daiichi Nuclear Power Plant (FDNPP) were identified in the atmosphere at 120 km distance from the FDNPP analyzing the ratio of number of atoms, following written as n(isotope)/n(isotope), of Pu and U. The n((240)Pu)/n((239)Pu), n((241)Pu)/n((239)Pu), n((234)U)/n((238)U), n((235)U)/n((238)U) and n((236)U)/n((238)U) in aerosol samples collected before and after the FDNPP incident were analyzed by accelerator mass spectrometry (AMS) and inductively coupled plasma mass spectrometry (ICPMS). The activity concentrations of (137)Cs and (134)Cs in the same samples were also analyzed by gamma spectrometry before the destructive analysis. Comparing the time series of analytical data on Pu and U obtained in this study with previously reported data on Pu, U, and radioactive Cs, we concluded that Pu and non-natural U from the FDNPP were transported in the atmosphere directly over a 120 km distance by aerosol and wind within a few days after the reactor hydrogen explosions. Effective dose of Pu were calculated using the data of Pu: (130 ± 21) nBq/m(3), obtained in this study. We found that the airborne Pu contributes only negligibly to the total dose at the time of the incident. However the analytical results show that the amount of Pu and non-natural U certainly increased in the environment after the incident.

Global deposition and transport efficiencies of radioactive species with respect to modelling credibility after Fukushima (Japan, 2011)

“…This is very important, as in case of nuclear accidents, concentrations close to the source are high enough to cause health problems to humans and the environment, and miscalculations may lead to unrealistic assessments that in turn can trigger panic among the members of the public. Moreover, a validation of several labile and refractory rare radionuclides ( 90 Sr, 95 Nb, 99 Mo, 110m Ag, 129m Te, 132 Te, 134 Cs, 136 Cs, 238 Pu, 239,240 Pu, 241 Pu, 241 Am) was also attempted using scattered measurements reported by several Japanese research groups (Doi et al, 2013;Igarashi et al, 2013;Kanai, 2012;Shinonaga et al, 2014;Thakur et al, 2013).…”

Simultaneous determination of radiocesium (135Cs, 137Cs) and plutonium (239Pu, 240Pu) isotopes in river suspended particles by ICP-MS/MS and SF-ICP-MS

“…Additionally, Fukushima accident-sourced Pu isotopes were also identified with high 240 Pu/ 239 Pu atom ratios (0.303-0.365) in litter, soil, aerosol and black substance samples [9,19,20]. These deposited radionuclides can be transported downstream to the ocean via inland river runoff.…”

Pu Distribution in Seawater in the Near Coastal Area off Fukushima after the Fukushima Daiichi Nuclear Power Plant Accident

“…In the terrestrial environment around the FDNPP site, the Pu isotopes released from the accident were characterized by high atom ratios of 240 Pu/ 239 Pu (0.30 -0.33) and 241 Pu/ 239 Pu (0.103 -0.135) [6], and were detected in various environmental samples, such as, soil, litter, dust (black substances) and aerosol samples and the total released amounts of Pu isotopes were estimated to be 1.0 -3.5 × 10 9 , 1.1 -2.6 × 10 11 Bq, and 2.9 -6.9 × 10 9 Bq for 239+240 Pu, 241 Pu and 238 Pu, respectively [3,[6][7][8][9][10]. However, the amount of Pu isotopes directly released into the marine environment remains unknown.…”