This chapter has covered the full scope of nuclear decommissioning and waste management, which together represent one of the most significant challenges facing the nuclear industry today. The key points are:
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Decommissioning is the complete process from end-of-life through D&D to delicensing and site release — not just dismantling.
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Nuclear facilities may be decommissioned for a variety of reasons including end of operating life, uneconomical operation, technical obsolescence, safety concerns, policy changes or following an accident.
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Decommissioning typically proceeds through three stages: initial decommissioning/POCO, partial dismantling with care and maintenance, and unconditional release/demolition. Alternative strategies include Safestore and Entombment.
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The NDA was established in 2005 under the Energy Act 2004 to take strategic responsibility for the UK’s nuclear legacy of 17 sites, including 39 reactors, 5 reprocessing plants and associated facilities, with an annual budget of approximately £3.24 billion.
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The regulatory framework includes the HSWA 1974, NIA 1965, IRR 2017, and numerous licence conditions (LC14, LC15, LC25, LC26, LC32-36) that specifically apply to decommissioning.
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Dose limits for the public are 1 mSv/yr, with source constraints of 0.3 mSv/yr and site constraints of 0.5 mSv/yr. The risk target for waste disposal is 10^-6 per year.
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Decommissioning requires extensive planning, with safety case documentation progressing through SJP, PSR, PCSR, PCMSR, SCS, CR, POSR and FSC stages, subject to a 5-stage approval process.
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Site characterisation involves historical assessment, scoping surveys, sampling and statistical techniques to build a radiological database for planning.
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Radioactive waste is classified differently by the IAEA (based on half-life) and the UK (based on activity concentration into Out of Scope Waste (formerly VLLW), LLW, ILW and HLW).
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Decontamination techniques include chemical (acids, solvents, LOMI), mechanical (water jetting, grinding, scabbling) and emerging methods (laser ablation, microwave scabbling, microbiological).
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Dismantling techniques include mechanical cutting, explosives, thermal/plasma arc cutting, water jet cutting and laser cutting.
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Waste treatment (HEPA filtration, evaporation, incineration, compaction) and conditioning (vitrification, cementation, bituminisation, polymerisation) convert waste to stable forms suitable for disposal.
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International disposal approaches vary significantly: the UK pursues a community-consent GDF programme; Sweden and Finland use the KBS-3 copper canister/bentonite/granite approach; France plans disposal in clay; the USA’s Yucca Mountain programme is halted; and Germany has restarted its site selection process.