Office for Nuclear Regulation

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Major steps forward in decommissioning work at Sellafield

12 January, 2018

Three major Sellafield projects that are subject to enhanced regulatory attention by ONR have made significant recent progress due in part to our engagement with the licensee.

These key achievements will help reduce hazard and risk at Sellafield which will further enhance public safety at the site.

Evaporator D

Evaporator D, SellafieldEvaporator D, Sellafield

In the first of these, Evaporator D – a new plant to support the site’s clean up mission – has just been ‘switched on’.

This follows a robust assessment and inspection programme by 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 start-up of the plant represents a major milestone in decommissioning at Sellafield. 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.

In the weeks ahead, Sellafield Ltd will steadily increase the radiological materials being processed through Evaporator D, overseen by ONR.

By March 2018 the intent is that Evaporator D will have taken over all highly active evaporation operations on site. Once fully operational, Sellafield’s older evaporators will be retired.

Pile Fuel Cladding Silo

Pile Fuel Cladding Silo, SellafieldPile Fuel Cladding Silo, Sellafield

Also in recent weeks, the sixth and final retrieval hole has been successfully 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 key regulatory priority for ONR.

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 gain assurance that the hole-cutting work could be progressed 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.

This project attracts significant regulatory attention by ONR. A team of inspectors continues to assess and inspect facilities that are needed to safely retrieve the waste from the silo.

First Generation Magnox Reprocessing Stack

B204 stack, SellafieldStack demolition, Sellafield

And the third piece of work is the demolition of 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.

ONR gave permission for demolition of the stack after close scrutiny to ensure Sellafield Limited can progress the demolition safely.

Inspectors have engaged with the site licensee during the design, build, testing and commissioning phases of the project.

The 60-year-old structure could only be removed once a modern replacement had been built. Conventional demolition techniques such as explosives and cranes could not be used due to the congested and hazardous nature of the surrounding area.

Instead, a cutting-edge self-climbing platform has been installed which moves up and down the barrel of the stack and allows workers to carry out demolition using hand held machinery.

Mina Golshan, Director of ONR’s Sellafield, Decommissioning, Fuel and Waste Division, said:

“We are pleased to see progress with these and other major decommissioning projects at Sellafield and acknowledge the hard work of the Sellafield Ltd teams to deliver these in a safe and timely manner.

“This is the beginning of a long journey to reduce the hazards and risks posed by these legacy facilities. Regulating these projects will therefore remain the focus of my team and ONR’s priority now and over the coming years.”

Photographs courtesy of Sellafield Ltd