Defuelling remains on course to be completed in September 2014 by which time 52,945 fuel elements will have been removed from site.
Tim Watkins said: “This is a significant milestone in Sizewell A’s lifecycle.
“It is only six months since we were marking 50 per cent defuelled; that shows how much progress is being made now we have priority for fuel transport flasks.
“Our highly-skilled teams continue to do a fantastic job, keeping the fuelling machines going and defuelling safely and efficiently.
“Removing spent fuel from reactors and transporting it to Sellafield for reprocessing is a complex process, but Magnox is using all its experience and expertise to deal with the legacy of this first generation of nuclear power stations.
“Once all the fuel has been despatched, we will have reduced the radiological hazard on site by more than 99 per cent.”
Dr Brian Burnett, Head of Programmes for the Nuclear Decommissioning Authority, which owns Sizewell A, said: “This is an important milestone on the site’s journey towards Care and Maintenance and a vital step in reducing hazard on the site.”