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Dounreay  - Cutting Up PFR Sodium Tanks

PFR Sodium Tanks Reach End Of Their Working Life 25 February 04
With the ease of a child, breaking off pieces of chocolate from a hollow easter egg, the oxy-acetylene cutter cuts up one of the giant PFR sodium tanks into manageable pieces.  There are ten of these tanks, each with a capacity of 143 tonnes fixed to plinths on the horizontal, within the sodium tank-farm.

Four of these tanks are currently being cut up, four are still in use and two are being retained as part of the Sodium Inventory Disposal plant.  The work is being carried out by JGC Engineering and Technical Services.

Prior to being cut up, each tank is stripped of all lagging and trace heating, and any other external appendages. Then all traces of sodium are removed, as project supervisor, George Campbell explained: “The tank in linked up to the water vapour nitrogen plant and this process, successfully trialled at Janetstown, turns any sodium residues into salt water. “There is no radiological contamination present, therefore we are able to dispose of the tank cuttings as clean waste.”

This means it can be taken off site to a licensed landfill site for burial.  Only when it is safe to do so can cutting up commence. Starting on the uppermost part of the tank a square ‘starter’ piece is cut out. This will be some 300mm square and will become the template for the remainder. Gradually the cutter works his way along both sides of the tank, and row by row the tank is gradually cut up. The thickness of the tank jacket is approx 25mm, and, as the latent force of oxygen and acetylene cut into the steel, a fan of sparks shoot out like some industrial Dante’s inferno!

As each piece breaks away it falls to the bottom of the tank. As it crashes down, metal against metal, its echo resounds throughout the building like a drum beating a lament for an era than has gone.

When it is safe to do so, the pieces are loaded into two skips to await their eventual removal from site.