Procedures of shielding analysis are described which were used for the shielding modification design of the Nuclear Ship "MUTSU". The calculations of the radiation distribution on board were made using Sn codes ANISN and TWOTRAN, a point kernel code QAD and a Monte Carlo code MORSE.
The accuracies of these calculations were investigated through the analysis of various shielding experiments: the shield tank experiment of the Nuclear Ship "Otto Hahn", the shielding mock-up experiment for "MUTSU" performed in JRR-4, the shielding benchmark experiment using the 16N radiation facility of AERE Harwell and the shielding effect experiment of the ship structure performed in the training ship "Shintoku-Maru". The values calculated by the ANISN agree with the data measured at "Otto Hahn" within a factor of 2 for fast neutrons and within a factor of 3 for epithermal and thermal neutrons. The γ-ray dose rates calculated by the QAD agree with the measured values within 30% for the analysis of the experiment in JRR-4. The design values for "MUTSU" were determined in consequence of these experimental analyses.
