Lord Hunt was shown inside the Dounreay Fast Reactor where work is well underway to destroy the hazardous cocktail of sodium and potassium liquid metal that was used as coolant in the 1950s experiment.
The coolant is contaminated with radioactivity from the fuel used in the defunct reactor and represents the second biggest single hazard in Britain’s £70 billion clean-up programme.
Its destruction is one of the strategic priorities of the UK Government’s Department of Energy and Climate Change.
Lord Hunt is the minister at DECC with responsibility for the Nuclear Decommissioning Authority, the public body now in charge of the Dounreay clean-up.
The NDA’s site programme manager Stuart Chalmers hosted a half-day fact-finding visit to Dounreay by Lord Hunt.
The Minister donned protective coveralls and radiation monitoring badges to step inside the sphere where workers are busy dismantling different bits of the reactor system.
Their big task at the moment is maintaining the steady and safe progress that’s been made so far to destroy the liquid metal that once carried the heat from the reactor through a series of circuits to generate steam for electricity production.
Approximately 15 per cent of the 57 tonnes of liquid metal has been destroyed so far using a chemical process that neutralises the alkaline metal and extracts much of the radioactivity, leaving a mildly contaminated salt water that can be discharged safely to sea.
Lord Hunt was also escorted by Mr Chalmers to see the decommissioning of the Prototype Fast Reactor, which in 1974 succeeded the experimental DFR.
There, he saw work underway to cut up gigantic tanks once used for another liquid metal, sodium, that flowed through the reactor.
Later, Lord Hunt stepped onto the floorslab of D8550 – all that now remains of the plutonium criticality laboratory that in the 1950s gave Britain the technical know-how for a rapid expansion of its nuclear programme.