1999.11.16
[Japanese]
Comparison of total radiation dose in Madi and Hengpizai village

　

Total radiation dose received by residents in Madi in High background radiation area (HBRA) is estimated to be 5.87mSv/y and in Hengpizai in control area (CA) 1.67mSv/y.

Dose estimation of residents in HBRA and CA（mSv/y）
Dose items
HBRA
(Madi, Yangdong county)
CA
(Hengpizai, Enping county)
External dose
3.54 *a
0.90 *b
Internal dose *c
Radon inhalation *d
1.24
0.49
Thoron inhalation *e
0.51
0.05
Food 40K *f
0.167
0.167
87Rb *e
0.006
0.006
238U + 232Th *g
0.41
0.055
Total dose
5.87
1.67


*a External dose includes cosmic, terrestrial radiations and radiations from building materials which contain radioactive substances. Indoor dose is thus about 0.39μGy/h, 1.5 times high as compared with the outdoor dose. Total external dose largely depends on occupancy factors which indicate relative time to be indoor. In this estimation the daily occupancy factors of 0.8 and 0.66 for summer and winter were used respectively.
*b

In Hengpizai in CA the indoor dose rate of 0.10μGy/h and the outdoor dose rate of 0.06μGy/h were used to obtain the annual dose of 0.90mSv.

*c For the estimation of internal dose all components shown in the table were summarized.
*d

Internal dose by radon was calculated based on air concentration of radon. Indoor radon concentration is higher than that of outdoor. Lower indoor radon concentration in summer and rainy season than in winter because of high ventilation by open window was taken into consideration for the estimation.

*e Estimated based on UNSCEAR report 1993.
*f According to the UNSCEAR report, the estimation was based on the following assumptions: K content 0.18%, 40K ratio 0.0012%, body weight 70 kg, and dose conversion factor 3μSv/y/Bq/kg.
*g Internal dose by food was estimated from the concentration of radioactive substances in the food and consumption of the food.