Posted on: 19th August 2013
When you take a flight on a Jet aircraft you must go through a number of checkpoints in the airport before and after your flight – security, passport control and so on. JET fusion experiment also has its own “airport” – the Beryllium Handling Facility: everything that goes in to and comes out of JET is processed there.
Calling it the Beryllium Handling Facility is perhaps inaccurate, as it is not only beryllium that is processed here. As well as the beryllium, which is toxic to humans, there are also radioactive components to be dealt with; either components that retain traces of radioactive tritium fuel, or that have been left radioactive by bombardment from neutrons emitted during fusion reactions. Within the 3 sealed workshops in the large assembly hall adjacent to the JET torus hall, components are inspected and cleaned, and waste is separated and bagged up ready for storage.
During a maintenance period on JET the facility is a hive of activity, says Leader of the Erosion and Deposition group Dr Anna Widdowson: “Space is at a premium, there are many different jobs going on around the facility. We have to have a coordination meeting every morning to ensure we are not competing for the same resources, or people – trained beryllium and radiation workers.”
Components removed from the experiment by the remote handling facility are placed straight into sealed containers – for example modified shipping containers – which can then carried by crane to the beryllium handling facility. In the case of the shipping containers, they have modified doors which attach straight onto the facility’s sealed area. Once connected the contents can be distributed to the different work areas – for example the ventilated “slit boxes” shown in the picture above. Airflow through the boxes funnels any loose material inwards, so that staff working on them are fully protected, says Support Technician Charlie Ayres.
“We have to wear full coveralls with powered air hoods, three layers of gloves; a thick sealed pair underneath some cotton gloves and sacrificial rubber gloves on top. You’re doing delicate work – complex processing or electrical work – with absolutely no feel at all.”
The air in the handling facility is replaced every six minutes and fully filtered before being ejected out of the stacks. Daily surveys by the health physics department monitor the levels of controlled materials within the facility and ensure they are well within environmental controls.
JET is the only tokamak in the world equipped with beryllium and tritium handling facilities. This makes the facility doubly important – not only because it enables unique experiments to be carried out, but also as it is a model for future tokamak sites. Of course the most notable of these is ITER, who have already visited Culham to ensure they learn from JET’s expertise.