Yoshihisa Hayashida

Shielding study of bremsstrahlung in bulk media with electrons part I: Monte Carlo calculation of thick-target bremsstrahlung spectrum

Abstract The electron-photon cascade Monte Carlo code, TAURUS, was developed for the calculation of gamma-ray and bremsstrahlung penetration in the matter of cylindrical and plane geometry bombarded by gamma-rays and electrons. This code treats the photon simulation with enough accuracy but the electron simulation with some simplification, because of speeding up the computing time and saving the core memory. The accuracy of the code was checked from the comparison with other experimental and calculated results of thick-target bremsstrahlung and was found to be good enough with small core memory and fast computing time.

Energy-Space Dependent Error Propagation in Monte Carlo Coupling Calculation

A new formulation of energy-space dependent propagation of errors has been derived for the Monte Carlo-Monte Carlo coupling technique which is applied to analysis of radiation streaming through a long path. In this formula, it is considered that the source uncertainty due to the statistical error of the preceding Monte Carlo calculation is handed down to a particle as an uncertainty of the particle weight. In the succeeding Monte Carlo calculation, the propagated weight error is scored together with the particle weight by flux estimators. The method has been implemented in the MORSE-ALB code system. As a sample problem, calculation of reaction rates in the main pump room of the primary coolant system of JOYO is performed with the Sn-AMC-AMC coupling technique. As a result, the present method turned out to be significant in estimating the Monte Carlo statistical error of the final value taking into consideration of the energy-space dependence of error propagation.

Improvement of Air Transport Data and Wall Transmission/Reflection Data in the SKYSHINE Code: (2) Calculation of Gamma-Ray Wall Transmission and Reflection Data

Transmission and reflection data of concrete and steel for 6.2 MeV gamma-ray in the SKYSHINE code have been generated using up-to-date data and method with a view to improving an accuracy of results. The transmission and reflection data depend on energy and angle. The invariant embedding method, which has merits of producing no negative angular flux and of taking small computer time, is suitable and adopted to the present purpose. Transmission data were calculated for concrete of 12 ~ 160 cm thick and steel of 4~39 cm thick based on the PHOTX library. Reflection data were calculated for semi-infinite slabs of concrete and steel. Consequently, smooth and consistent differential data over whole angle and energy were obtained compared with the original data calculated by discrete ordinates Sn code and Monte Carlo code. In order to use these data in the SKYSHINE code, further verification is needed using various calculation method or experimental data.