It has taken eight years to clear three plants in Tennessee that made enriched uranium for the USA’s nuclear power industry, and of course, for the nuclear deterrent. The plants were closed in the mid-1980s after 30 years of operation.

By the time it had finished in March 2005, lead decommissioning contractor BNG America had removed and dismantled 3,000 converters and compressors, decontaminated 20m sq ft (1.8m m2) and disposed of 360m lbs (163,000 t) of contaminated material from the K-33, K-31 and K-29 gaseous diffusion plants at the old Oak Ridge, Tennessee K-25 site, now called the East Tennessee Technology Park.

You cannot simply knock down a factory full of thousands of tonnes of pipes and compressors, and loaded with radioactive material, asbestos, chlorofluorocarbons, polychloride biphenyls (PCBs), and other hazardous materials. Such an approach would take too long, and be too dangerous.

Instead, the plan was to disassemble the plant, taking apart cell dividers, pipe racks, and bigger equipment, and to cart it all away for burial or reuse.

&#8220-BNG America, on the scale of the lifting management job of the project”

Multiple configurations of components, the large numbers and amounts of materials, and the high weights of many pieces of equipment required rigorous attention to worker qualification, training, lift planning, selection of the proper rigging equipment, and carrying out multiple and various lifts daily.

To do this, BNG America refurbished, recabled and tested more than 30 existing P&H cranes originally installed by the Birmingham, Alabama-based firm 40 years ago. The cranes were rated for loads up to 40 US tons. They lifted stacks of equipment and helped transport them to the next area.

BNG brought in some extra muscle to handle the larger pieces – a huge hydraulic compactor capable of crushing two cars with engines into a square the size of a coffee table. It set up a special shop for the supercompactor, crushing 50 US tons an hour, with three new 21 US ton bridge cranes.

With up to 1,400 people working on site, and thousands of lifts to perform, the decommissioning job was complex. “Multiple configurations of components, the large numbers and amounts of materials, and the high weights of many pieces of equipment required rigorous attention to worker qualification, training, lift planning, selection of the proper rigging equipment, and carrying out multiple and various lifts daily,” a spokesman for BNG America said.

To deal with the management complexity of the job, the team organised lifting operations by difficulty: ordinary, critical and engineered. Critical lifts involved loads between 90% and 100% of the crane’s capacity and risked personnel injury, exposure to radioactive material, or property damage. Critical lifts required an engineering review and exceptional handling care. Engineered lifts involved loads between 100% and 125% of rated crane capacity. They required engineering approval and a documented and rigorous lift plan.