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.
||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.
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.
||For the estimation of internal dose all components
shown in the table were summarized.
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.
||Estimated based on UNSCEAR report 1993.
||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.
||Internal dose by food was estimated from the concentration
of radioactive substances in the food and consumption of the food.