15 Jan (NucNet): Significant recent progress has been made at three Sellafield projects that have been subject to increased regulatory attention the UK’s Office for Nuclear regulation said on 12 January 2018.
The ONR said these “key achievements” will help reduce hazard and risk at Sellafield, the legacy nuclear site in northern England that is undergoing decommissioning.
In the first of these, Evaporator D – a new plant to support the site’s clean up mission – has been started up following assessment and inspection by the ONR to regulate the design, construction and now the commissioning of the plant.
Evaporator D acts like a giant kettle, using evaporation to reduce the volume of highly active liquid so it can be turned into glass form and safely stored. This will enable Sellafield to complete reprocessing activities and further focus on the decommissioning and clean-up of the site.
The ONR’s assessment of Evaporator D started in 2005 and considerable work has been done in regulating the design, construction and now commissioning of the plant.
Also in recent weeks, the sixth and final retrieval hole has been cut at the pile fuel cladding silo (PFCS.)
Commissioned in 1952 to support the UK’s nuclear weapons programme, the silo represents one of the largest hazards at Sellafield and the safe decommissioning of the building is a regulatory priority.
Gaining access to the waste inside the silo is one of the most complex projects in Sellafield’s history. A team of ONR inspectors has carried out extensive assessments and inspections to make sure that the hole-cutting work can be carried out safely. Six massive steel containment doors are now in place over each hole ahead of retrieval work to export the waste to a modern-standard storage facility.
The third piece of work is the demolition of first generation Magnox reprocessing stack, one of the tallest structures on the Sellafield site, which no longer meets modern construction standards.
The height of the redundant chimney on top of the oldest reprocessing plant will be reduced at a rate of one-metre a week, resulting in “a significant reduction in hazard and risk”.
The ONR said it had given permission for demolition of the stack after close scrutiny to ensure Sellafield Limited can progress the demolition safely.
The Sellafield site comprises of a range of nuclear facilities, including redundant facilities associated with early defence work, as well as operating facilities associated with the Magnox reprocessing programme, the thermal oxide reprocessing plant (Thorp), the Sellafield mixed oxide fuel plant and a range of waste treatment plants.
It began life in the early 1950s making plutonium for nuclear weapons, and later that decade became the location of Calder Hall, the world’s first commercial nuclear power station.
The government said Sellafield consumes about 60% of the Nuclear Decommissioning Authority’s £3bn ($4.1bn, €3.3bn) annual budget and houses most of the UK’s civil nuclear waste.
