Determination of Radionuclides Surface Concentration and Radiation Level in Fukushima Prefecture, Japan

Godwin Ekong, Isa Sambo, and Saiyadi Sulaiman

Nigerian Nuclear Regulatory Authority, Nigeria

Abstract: The determination of radionuclides and radiation levels in some of the most affected area of Fukushima, Japan (Lat. 37046N Long. 140028E) after the 2011 Tsunami employing the use of Radiagem 2000/Rados (RDS-31) dose rate meter for radiation survey measurement and hand held Hyper pure Germanium (HpGe) detector for in-situ Surface Concentration (SC) measurements was the aim of this study. Six (6) different locations were measured and analyzed, Insitu surface concentration measurements prominently of 134Cs at energies 569, 605 & 796 keV and 137Cs at energy 662 keV were established with little radiation from NORM alongside with dose rate measurement at the same locations. The ability of the detector to measure a Minimum Detectable Activity (MDA) as low as (0.10±0.02) Bqm-2 from a background area of about 400 m2 established 95% of confidence limit on detection before commencing the Insitu measurements. The ranges of Insitu SC measurements for 134Cs and 137Cs for the Locations were found to be (162.11±0.46–59,649.39±6.61) Bqm-2 and Dose Rate measurements for the same locations were found to be (0.87±0.03–22.84±1.26) μSvh-1respectively. The presence of 134Cs and 137Cs in these locations of Fukushima Prefecture, Japan showed an evidence of the nuclear accident as a result of the Tsunami disaster. The radiation levels recorded during the monitoring exercise was above the value of 0.2 μSvh-1 which Japanese Government hopes to achieve at the end of it ongoing environmental remediation before re-habitation of it evacuated citizens.

Key words: radiological monitoring, radiation, environment, fukushima