Nuclear Technology / Volume 168 / Number 2 / November 2009 / Pages 467-471
Shielding / Special Issue on the 11th International Conference on Radiation Shielding and the 15th Topical Meeting of the Radiation Protection and Shielding Division (Part 2) / Radiation Protection
A shielding layout for a 40-MeV electron linac is presented. The linac building consists of 15-cm concrete roof and walls, and 2-m-thick shielding walls for horizontal shielding. No shielding roof covers the linac, which reduces the capital cost of the facility building. Though the present shielding layout allows an operation of up to 11.8-W averaged beam power, experimental dose equivalent rates are found to be much greater than that predicted by the skyshine formula. Monte Carlo (MCNP 4C) simulations indicate considerable contributions of radiation scattering by the thin roof and walls.