As one of the DD&A framework contractors with Magnox, Squibb Group were contracted to work with Magnox in order to execute design requirements, remove the radiological contamination, decommission and eventually demolish the GHF at Chapelcross.
The scope of the project involved the demolition of the Graphite Handling Facility in its’ entirety. This included the remediation/removal of radiological contaminated sections within the floor slab including the mortuary holes and the graphite storage areas. The work also included the removal of the contaminated, redundant ventilation plant from within and outside the building.
There was also a requirement to remove the radiological contaminated drainage system and remediate land in the immediate vicinity of the building as identified in functional specification. The area was landscaped when the building had been removed and handed back to the client.
The remit of Squibb Group was to review previous investigational data and reports provided by Magnox Chapelcross and undertake additional radiological surveys. The surveys included intrusive sampling to support characterisation of the facility and sub soils, which then enabled development of a conceptual design for consideration and agreement by Magnox.
Next stage was to develop a detailed design, including sequencing and methodology for safe demolition, remediation and removal of the facility. Work scope was then produced along with procedures, specifications, safe systems of work packages, method statements and risk assessments. Squibb also provided assistance to the Magnox Project Team covering waste characterisation, land quality, radiological protection, safety case development and plant modification proposals
The physical works were executed with precision and in accordance with the demolition programme in the following sequence. Site set-up, which involved the delivery of cabins and equipment for the set up and security of the area prior to the capping of the drainage system, which was a requirement in order to prevent any access/egress of contamination to/from the building. This task was followed by the radiological decontamination of the building prior to the soft strip of areas A & B. After the soft strip of the building the internal ventilation system including the ventilation motors were removed. This was followed by the removal of the contaminated internal crane.
Located in a pit was the Hunterston Cell, which required the removal of all contaminated water p rior to removing the internal furniture. The Hunterston pipe was the greatest radiological hazard within the facility. The programme continued with the removal of the contaminated large and small mortuary tubes. The contaminated floor in area B was decontaminated and samples taken for analysis prior to the removal of the internal cladding. The final declassification/clearance survey allowed for the removal of the asbestos roof and declassification of the building.
Removal of the external ventilation system in area D allowed the demolition of the building to be carried out on programme. With the building demolished the crane gantry was removed and consigned as active waste. The programme continued with the controlled removal of the reinforced building slab, footings and extra works which included the removal of the contaminated drainage system prior to ground levelling and remediation.
The site was handed back to the client within programme and budget.