In this paper

atmospheric dispersion of 131I from a loss of coolant accident(LOCA) at the proposed Taohuajiang nuclear power plant(NPP) is simulated with the CALPUFF modeling system.The following results are obtained:(1) Within a few hours after the accident

at the grid point in the downwind direction

which is about 8 km away from the source

the 131I concentration forms a peak of air-time integration activity

because the altitude is as high as effective height of the source

while it is the highest in the downwind direction.(2) Among the three chemical forms of iodine

elemental iodine is the most likely to deposit

with the same contour distribution of deposited activity in the ground as the time-integrated air concentration.(3) The dose equivalent resulting from 131I internal exposure caused is far greater than external exposure

hence the need of

should a LOCA occur

preventing radioactive materials from entering human body via the respiratory tract

oral cavity and skin wound

so as to greatly reduce the 131I radiation dose equivalent.