Estimation of beta-ray skin dose from exposure to fission fallout from the Hiroshima atomic bomb

Beta-ray skin dose due to the fission fallout from the Hiroshima atomic bomb is potentially related to the epilation in the black rain area. The absorbed dose to the skin from beta-rays emitted by fission fallout has been estimated for an initial 13?Cs deposition of 1 kBq m?2 on the ground at 0.5 h after the explosion. The estimated skin dose takes into account both external exposure from fission fallout radionuclides uniformly distributed in 1 mm of soil on the surface of the ground and from a 26 μm thickness of contaminated soil on the skin, using the Monte Carlo radiation transport code MCNP-4C. The cumulative skin dose for 1 month after the explosion is taken as the representative value. The estimated skin dose for an initial 13?Cs deposition of 1 kBq m?2 was determined to be about 500 mSv.