Dose Rate Calculations for Transport of Vitrified Residues by Sea·

It is planned that vitrified residues (high level waste, (HLW)) from fuel reprocessing operations in Europe will be transported in purpose-designed vitrified residues flasks by sea to Japan. This paper describes gamma and neutron radiation dose rate calculations which were performed to allow the carriage of a maximwn of 14 flasks on board typical Irradiated Nuclear Fuel vessels. These flasks may be carried in Holds 1, 2, and 3 of each ship, with a nwnber of empty oxide flasks in other locations in Holds 4 and 5. As the exact loading plan of the empty oxide flasks will vary from voyage to voyage, for pessimism, no empty flasks were included in the geometric models of the ship (as these would provide extra shielding). Dose rates at off-center-line points in the accommodation areas and regularly occupied working spaces, athwartships of points immediately aft of the center-line of the house front, and those just aft of the shielding tank have been assessed. In addition, dose rates have been calculated above the hatchcovers and on the external surface of the ships' hulls.