Application of new calculation methods to the primary shielding of the avr experimental reactor

Abstract The DOT/RATRAC code system has been verified by comparison with gamma and neutron dose rates and neutron energy spectra measured at AVR experimental reactor (HTGR-type reactor). The RATRAC module was recently developed for improving transport calculations for complex configurations containing extended voids and for saving computing time. In RATRAC the angular flux density at the surfaces of the voids is described in terms of spherical harmonics and the radiation transport through the voids is treated analytically. It turns out, that the theoretical results and the values measured at the AVR reactor are in good agreement, even on top of the reactor building.