Abstract
The skyshine dose from the turbine building (T/B) at a BWR commercial plant in Japan was calculated using a Monte Carlo code, a parallel version of MCNP5. The inner and outer walls of the T/B, shielding material around a high pressure turbine (HP-T), the HP-T itself, low pressure turbines (LP-Ts), and the pipes installed on the operating floor in the T/B were considered and modeled in detail. Much computing time is required to perform the MCNP calculation with the detailed calculation model mentioned above. In this work, a 10-node cluster with 3.2-GHz CPUs was applied to the skyshine calculation for reducing the computing time. On the other hand, the skyshine doses were measured with a NaI scintillator as the pulse-height spectra at a few points around the same T/B that was analyzed in the above calculation. In order to validate the MCNP calculations, the results were compared with the measured data, and the skyshine dose distributions calculated by MCNP were also compared with those obtained by other calculation codes--SKY-H (a code similar to G-33) and SKYSHINE code. It was found that MCNP yields a sufficiently precise skyshine dose distribution from the T/B at a BWR plant and is suitable for skyshine estimation.
