Transportable radioactive waste processing facilities can be an attractive alternative to the building of large facilities with fixed canyons or PSCs. Transportable facilities are particularly attractive when processing is expected to be complete within short timescales, when it is advantageous to be able to move the processing equipment within a facility or amongst a series of geographically disperse waste treatment sites, or when the exten­sive decommissioning and clean-up of a large fixed facility is considered undesirable. Phillips (2008) has produced comprehensive review of trans­portable processing systems.

Transportable processing equipment is typically constructed within stan­dard steel ISO-containers, or similar sized spaceframes, and includes por­table ventilation and off-gas equipment added as required. The ISO-containers are shielded and confined as necessary by the addition of steel shielding and confinements to the outside of the containers. Alternatively the ISO-containers are placed within separately constructed concrete enclosures that do not come into contact with any radioactive material and thus do not themselves require any radioactive decommission­ing at mission end.

Within the shielded confinements maximum use is made of systems that greatly minimize the use of moving parts, substituting these with non­moving process equipment and instruments based on fluidics and com­pressed air. Additionally, use is made of “through-wall” drives where moving parts are located outside the shielded ISO-container, with only a shaft drive penetrating the shielding and connecting with the in-container processing equipment. These design provisions enable the placement of most mechani­cal items and instruments requiring maintenance outside the shielding and thus accessible, and ensure that there is no need for personnel to enter the shielded parts of the containers during the life of the system. The Mobile Solidification System (MOSS, Fig. 3.18) is a typical system developed for

use at the Hanford, WA nuclear reservation for the transfer, conditioning and solidification of radioactive sludges from the reservation’s K-Basins, previously used for the underwater storage of UNF.