Syllabus Coverage: NFC5.3, NFC5.4
Dismantling operations are normally carried out after decontamination has been completed. Dismantling is normally considered to be the final phase of the decommissioning operations. Desirable techniques should produce minimum secondary waste, offer low dose burden, be efficient and cost-effective.
| Technique | Description | Application | Considerations |
|---|---|---|---|
| Mechanical shearing/sawing | Conventional cutting tools adapted for radiological environments | Pipes, structural steel, vessels | Can be operated remotely or manually; produces solid swarf |
| Explosives (conventional) | Low detonation speed; seed charges placed at pre-defined critical points | Large solid structures: exhaust stacks, cooling towers, biological shields | Remotely detonated; good for large-scale demolition |
| Explosives (shaped) | High detonation speed; V-shaped blade propelled by detonation | Large-diameter pipes; controlled fracture at precise points | Linear shaped charges for precision cutting |
| Thermal (flame) cutting | Oxy-acetylene or oxy-propane flame cutting | Steel structures; above and underwater | Faster than mechanical; produces aerosols and dust requiring HEPA filtration |
| Plasma arc cutting | High-temperature ionised gas stream | Steel and reinforced concrete; above and underwater | Very fast; lighter equipment; significant aerosol generation |
| Abrasive water jet cutting | Abrasive material (e.g. sand) propelled by high-pressure water | Reinforced concrete (primary application); any material | Produces large amounts of secondary waste |
| Liquefied gas cutting | Liquefied gas (e.g. nitrogen) used as propellant instead of water | General metallic and concrete structures | Produces hardly any secondary waste; no fire/explosion risk; remotely operable |
| Laser cutting | Laser beam concentrated on object, heating locally beyond melting point | Remote cutting using fibre optics | High start-up/capital costs; not yet widespread |