A comparison of the dose from natural radionuclides and artificial radionuclides after the Fukushima nuclear accident

Abstract

Due to the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, the evacuees from Namie Town still cannot reside in the town, and some continue to live in temporary housing units. In this study, the radon activity concentrations were measured at temporary housing facilities, apartments and detached houses in Fukushima Prefecture in order to estimate the annual internal exposure dose of residents. A passive radon–thoron monitor (using a CR-39) and a pulse-type ionization chamber were used to evaluate the radon activity concentration. The average radon activity concentrations at temporary housing units, including a medical clinic, apartments and detached houses, were 5, 7 and 9 Bq m−3, respectively. Assuming the residents lived in these facilities for one year, the average annual effective doses due to indoor radon in each housing type were evaluated as 0.18, 0.22 and 0.29 mSv, respectively. The average effective doses to all residents in Fukushima Prefecture due to natural and artificial sources were estimated using the results of the indoor radon measurements and published data. The average effective dose due to natural sources for the evacuees from Namie Town was estimated to be 1.9 mSv. In comparison, for the first year after the FDNPP accident, the average effective dose for the evacuees due to artificial sources from the accident was 5.0 mSv. Although residents' internal and external exposures due to natural radionuclides cannot be avoided, it might be possible to lower external exposure due to the artificial radionuclides by changing some behaviors of residents.

Short Telomere Length as a Biomarker Risk of Lung Cancer Development Induced by High Radon Levels: A Pilot Study

“…The reference value of the radon concentration in the radon chamber was based on the measurement values obtained from the standard ionization chamber. The details of the radon calibration chamber and the calibration conditions of AlphaGUARD at NIRS-QST were previously described [ 17 ].…”

Environmental Radiation Monitoring and External Dose Estimation in Aomori Prefecture after the Fukushima Daiichi Nuclear Power Plant Accident

“…The external dose estimation method in this study was different from that used by IYOGI et al Thus, although it is dif cult to compare these external doses directly, the annual effective doses seemed to have generally good agreement. Additionally, the nationwide average of the annual effective dose by terrestrial gamma-rays 16) is 0.33 mSv, and the average value for all of Aomori Prefecture was 59% of the nationwide average value. 169 ± 5 9 ± 1 9 ± 1 a The numbers refer to the designations in Fig.…”

“…15) Portable type NaI(Tl) scintillation survey meters which were calibrated by the same ionization survey meter were used for this nationwide survey, and almost all the measurements were made on the grounds of schools located in each prefecture. 14) According to the results by this nationwide survey, 15,16) the arithmetic mean of absorbed dose rate in air by terrestrial gamma-rays was reported as 50 nGy h -1 , and the annual effective dose was 0.33 mSv. Two nuclear power plants (NPPs) and Japan's rst commercial nuclear fuel cycling facilities are located in Aomori Prefecture (Fig.…”

Whole-Body Counter(WBC) and food radiocesium contamination surveys in Namie, Fukushima Prefecture

“…Namie is located in the northern part of Fukushima Prefecture in Japan, and its population was around 21,000 when the Great East Japan earthquake struck. Namie is located about 4 km away from the power plant and the residents were evacuated considering the impact of the accident [2], (Fig 1). The exposure of the thyroid to I-131 was considered problematic at the initial stages of the accident based on the lessons learned from the Chernobyl nuclear power plant [3,4].…”