Disposal of Dragon tanks

March 29, 2011

The SGHWR/Dragon Project team at Winfrith instigated a re-appraisal of the plan for processing and disposal of 17 tanks from the Dragon Reactor project which had moved into a care and maintenance phase. This reappraisal centred on innovation and carrying the work out in house rather than sending it via the planned option of a specialised subcontractor.

The primary obstacle to processing the waste at Winfrith was the lack of suitable containment for the task of cutting up the tanks, which would have been prohibitively expensive owing to the not inconsiderable size of the tanks.

In response, the SGHWR/Dragon project team developed a technique which would allow the tanks to be size reduced using the tanks themselves as their own containment. In the case of 12 out of the 17 tanks, the technique led to the tanks being size reduced outdoors by means of hot cutting.

The innovative technique initially centred on a small hole being cut in the tanks to allow a preliminary internal activity survey and local decontamination. Having established the level of contamination on the internal surfaces, a larger hole was cold cut into the tank sufficient to allow partial man access and to test the effectiveness of the non-aggressive decontamination method. Subsequently, a much larger hole was cut into the tank to provide full man access.

Full decontamination of the tank internal surfaces was carried out in this way. As a consequence, fast and efficient size reduction of the first 12 tanks was possible outdoors, using hot cutting methods with good access and manoeuvrability and without the need for special containment. This also allowed maximisation of exempt material as the contaminated components could easily be reduced to their minimum size.

The ability to process the waste in house permitted optimal use of existing manpower. Quiet phases or delays in existing work schedules were utilised to the full and complementary jobs were combined. Full control over processing the waste allowed RSRL to benefit whenever it was possible to achieve disposal of the (nominally) low-level waste by an exempt route. Overall, substantial savings were made possible using a combination of the aforementioned techniques.

For more information please contact Emma Burwood, RSRL Communications Manager