Measurement and analysis of gamma-ray dose distribution in actual ship.

Abstract

Gamma-ray dose distribution was measured in an actual ship to study applicability of point kernel method popularly applied to the calculation of γ-ray dose distribution in ships which have usually compartmentalized structures. Measured distribution was used to verify applicability of Monte Carlo method to the analysis of γ-ray dose distribution in the ship. Monte Carlo method was proved to be effective for analysis of r-ray dose distribution in the ship. Monte Carlo analysis revealed that γ-rays scattered back from steel plates constructing ship hull increase their contribution to measured dose value as the distance between the dose measuring point and γ-rays sources increases. This contribution has not been taken into account in dose distribution calculations for ships by the point kernel method with the usual buildup factor. Present study also disclosed that feasibility of applying Monte Carlo method to the analysis of γ-rays dose distribution in ships will be enhanced remarkably by utilizing the function adopted in the subroutine RELCOL in the Monte Carlo code MORSE-CG and by applying the source direction biasing technique to save machine time and to improve statistics of the calculated results.