PACIFIC SANDPIPER DOSE RATE ASSESSMENT FOR THE CARRIAGE OF SELLAFIELD VITRIFIED RESIDUES

Vitrified Residues produced at the Windscale Vitrification Plant, Sellafield will be transported from Barrow, on board Pacific Sandpiper, to the storage facility in Japan. The vitrified residues will be transported in two different vitrified residues transport (VRT) flasks. This paper describes the radiation dose rate assessment to examine a possible 10 loading locations for such flasks on board Pacific Sandpiper. The ideal scenario is to be able to carry 10 flasks of one type or a combination of the two flask types. All flasks will be carried in Holds 1 to 3. Dose rates in the accommodation areas and regularly occupied working spaces have been calculated. The most onerous dose rates for centre-line and off centre-line positions have been presented. Additionally, dose rates were calculated on the surface of, and at 2m from, the hatchcovers and the ship's hull plating. The number of flasks capable of being transported without these dose rates exceeding the criteria has been determined to be 9 flasks of one type or a combination of the two flask types. It has been demonstrated that it would be possible to carry 10 flasks in Holds 1 to 3, if additional shielding were provided for the Hold 3 flasks during the voyage, should this maximum loading plan ever be required.