Decommissioning Opportunity Blasts Niche For Wheelabrator

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Wheelabrator supplies a £350,000 abrasive blasting unit on behalf of customer RWE NUKEM to the European Commission’s Joint Research Centre (JRC) in Ispra, Italy for the decontamination of materials at the nuclear facility.

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As the European Commission's science and knowledge service, the Joint Research Centre's mission is to support EU policies with independent evidence throughout the whole policy cycle. Its work has a direct impact on the lives of citizens by contributing with its research outcomes to a healthy and safe environment, secure energy supplies, sustainable mobility and consumer health and safety.

Retos

A Wheelabrator R3d (V) Euro Tumblast machine, traditionally used in heavy duty metal foundries, is used to decontaminate metal components and concrete blocks as part of JRC-Ispra’s extensive decommissioning programme.

Contaminated material is produced when active nuclear facilities are decommissioned at the end of their useful life.

Demolition of buildings creates large amounts of components, such as bricks, stone, steel and other structural material, considered to contain low levels of radioactivity within the surface layer.

Phil Smith, senior project manager at nuclear engineering specialist RWE NUKEM, said: “JRC Ispra has initiated a programme to reduce costs and minimise radioactive waste quantities, a major component of which is the decontamination of materials to clearance levels suitable for unconditional release in line with EU directives.”

La solución

Custom built by Wheelabrator, design modifications were required to the R3d (V) machine to fit the low headroom at its new home and enhance its safety features.

A team of seven people from Wheelabrator Group worked in conjunction with engineers from Warrington-based RWE and JRC Ispra to tailor the machine.

Mr Smith said: “The team at Wheelabrator Group have been very helpful. Projects such as these are never easy, but our good working relationship has allowed us to tackle the challenges presented together and develop solutions to solve these.

“The nuclear sector is one of the world’s most demanding industries with highly detailed specifications and exacting requirements.”

Located in Area 40 at the Ispra site, the unit replaced the old and obsolete chemical baths. A secondary containment wall and airlock was added to the room to reduce noise levels and aid contamination control.

With a 700 litre capacity, material to be processed in the machine is sealed in 220 litre drums and transferred to the machine via a hydraulic loader. Operators key in commands via a touch screen console located safely outside the secondary containment wall.

The main chamber is equipped with two Ezefit blast wheels, each with six blades and driven by a direct couple motor, which propels the sharp steel grit onto the contaminated components, removing the surface layer including any contamination. A heavy duty steel slatted mill creates a continuous tumbling action to ensure complete coverage of the components in one cycle.

Typically 30 minutes will remove contamination from metal components to below required clearance levels whilst 10 minutes will be sufficient for concrete.

Cleaned off contaminants are then fed to collection bins and the dust created bagged in secure waste drums. These can then be disposed of in accordance with the relevant legislation.

The steel grit is recycled within the machine via an airwash separator with a second magnetic particle separator and cleaned air returned to the room after passing through primary filters and an additional TROX air conditioner.

Lawson Pryke, technical director at Wheelabrator Group, said: “This abrasive blasting decontamination technique can be used to effectively reduce the amount of radioactive waste apparent with larger quantities of contaminated materials. The process produces fully decontaminated materials suitable for release, leaving a small amount of contaminated material in the form of dust, fines and paint residue, with reduced requirements for treatment and disposal.”

A four-day training course was provided onsite to all employees operating the machine. Installation, proving, spares and service is supplied by the group’s aftersales specialists, Wheelabrator Plus.

El resultado

In 1996 the Wheelabrator Group demonstrated the effectiveness of using abrasive blasting as a decontamination technique at Belgoprocess in Belgium.

Alternative waste and material management routes such as supercompaction and disposal are typically three times more expensive than dry abrasive blasting.

Mr Pryke said: “Abrasive blasting machines offer huge economic benefits and have added environmental advantages by effectively reducing slightly contaminated material to a state which allows disposal with no negative side effects. A large amount of material can also be released for recycling.”

JRC-Ispra opened in the early 1960s as part of a network of research centres located in different member states set up to provide customer-driven scientific and technical support for European Union policies, linking industry, universities and institutions as well as carrying out studies and experiments.

Contributing to the establishment and growth of nuclear power related industries, the Ispra site undertook research into reactor development and the fuel cycle. As the research progressed, a variety of additional experimental facilities, including reactors, hot cells, radiochemical plants and waste management stores were built.

Since the early 1980s, the European Commission has progressively reduced its focus on nuclear research and development at Ispra, instead expanding activity into food safety, genetically modified organisms, chemicals and the environment.

Mr Smith said: “With the global move away from nuclear facilities, the industry is faced with a large stock of potentially contaminated buildings and equipment. The need to comply with legislation governing decommissioning has driven the nuclear industry to review wider applications in the search for a solution.”

Market leader in supplying this kind of service to the nuclear industry, its involvement extending over 20 years, Wheelabrator Group supplies standard and bespoke machines costing from about £150,000 upwards.

The group has a long established relationship with the nuclear industry, in the UK alone its machines can be found in Sellafield in Cumbria, Capenhurst in Cheshire and Winfrith in Dorset.