UKAEA, Dounreay

Mechanical and electrical contract at UKAEA, Dounraey

Facts and figures

  • The Dounreay Fast Reactor was built on a green field site during the 1950’s, it was commissioned in 1958 and operated until 1977 when it was shut down
  • The steel sphere containing the reactor is a well-known landmark and after decommissioning the sphere and control room will be the only remaining buildings on site, forming a visitor attraction

Innovations in operational efficiency

Interserve was selected by UKAEA at Dounreay to join the Primary Circuit Decommissioning (PCD) Alliance as the Mechanical and Electrical Contractor.

The alliance was formed to construct and operate facilities to allow the removal and disposal of 9,000 metres of contaminated pipework from the Dounreay Fast reactor vault. A further lump sum contract was awarded in January 2002 for the removal of Mechanical, Electrical and Insulation from the secondary Sodium Cells of the Prototype Fast Reactor (PFR). The plan is structured to achieve removal of the main radiological sources by 2025 and a complete return of the site to its original state by 2050 at a cost of some £5 billion.

There were many components to remove and the removal sequence was complex. Due to the limited working space and access, the dismantling equipment had to be frequently relocated to allow the removal of the discarded parts. This necessarily led to a complex processing sequence.

The general approach to the demolition was the dismantling of buildings using techniques, in an opposite sequence, to the operations envisaged during the erection process.

After removal of the wetted Nak pipework, all other plant and equipment isolations were carried out. Sequenced removal of all building services, including the existing nitrogen pipework commenced, this was followed by the removal of all of the remaining plant and equipment. This phase included the removal of pumps, generators, control circuitry, electrical control boxes and the clearing of all other internal and external fixtures and fittings.

The first major dismantling operation was to remove all non-structural elements of the external envelope, such as cladding. This operation was followed by the structural members being removed in an appropriate manner. The dismantling operations involved the sequenced removal of all individual elements of the structure, as opposed to the more usual deliberate collapse techniques, where the building is demolished in a single operation then cut into manageable sections for disposal.