The methods and processes for managing waste produced by the nuclear industry are comprehensively regulated in the UK. This regulation governs how nuclear operators – including EDF Energy – manage waste from existing plants and how waste from proposed new plants will be managed. As part of the site licence and permits granted to EDF Energy by the Office of Nuclear Regulation and the Environment Agency (or Scottish Environment Protection Agency), the company is obliged to keep the accumulation of radioactive waste as low as reasonably practicable ( known in the nuclear industry as ALARP).
There is no mystery surrounding the nature of radioactive wastes: they behave predictably and their radioactivity declines over time. The vast majority – some 97% – becomes nonhazardous over a matter of decades. The radioactivity in fission products divides by ten roughly every ten years. So after 40 years, the level of heat and radioactivity is around a thousandth of what it was when removed from the reactor.
Solid nuclear waste products are classified into three categories – high, intermediate and low-level – based on their level of residual radioactivity. The categories define how each waste product must be treated.
High-level waste (HLW)
HLW accounts for 95% of the radioactivity of the world’s radioactive waste but makes up just 3% of the volume. As of 1 April 2010, all the high-level waste in the UK would fit in a 12.3m (40ft) cube.
The only source of HLW from EDF Energy’s reactors is from the reprocessing of spent fuel. After an appropriate period of cooling on-site, spent fuel from EDF Energy’s advanced gas-cooled reactor (AGR) fleet is sent to Sellafield where it is either reprocessed or stored. Reprocessing separates out the potentially reusable uranium and plutonium and produces a small quantity of HLW which is vitrified (solidified in glass) and stored at Sellafield. The spent fuel which is not reprocessed is stored long-term. All HLW and spent fuel is highly regulated and securely stored until a long-term geological disposal facility (GDF) is made available by the UK Government.
The spent fuel from Sizewell B’s pressurised water reactor (PWR) is stored on the Sizewell B site until a GDF is available. Transport of spent fuels and wastes is also highly regulated.
Intermediate-level waste (ILW)
Decommissioning a nuclear power station at the end of its working life is the main source of ILW, although some is also generated during operation. EDF Energy currently stores ILW on-site at its nuclear power stations. When the company decommissions a reactor in England and Wales, ILW will continue to be stored on the decommissioned site until a GDF is available.
Long-term, near-surface, near-site storage and disposal is the Scottish Government’s policy for ILW and long-lived low-level waste (LLW) in Scotland. EDF Energy’s approach to managing waste arising from the decommissioning of power station sites in Scotland is in keeping with this policy. ILW will continue to be stored in robust facilities on decommissioning sites until the near-surface facility disposal route is available. Reprocessing nuclear fuel also produces ILW and LLW which is managed at Sellafield.
Low-level waste (LLW)
Items which have become contaminated with small amounts of radioactivity, such as paper, rags, tools and protective clothing, are classified as low-level waste. EDF Energy has a contract with the LLW Repository in Drigg, Cumbria for disposal, as do the other UK nuclear operators.
Discharges to the environment
As well as disposing of solid waste, EDF Energy also discharges low-level radioactive gases and liquids into the air or sea under strict permits or authorisations from the UK environment agencies (the Environment Agency, EA, and the Scottish Environment Protection Agency, SEPA). The EA regulates radioactive discharges and disposals from nuclear power stations in England and Wales under the Environmental Permitting (England and Wales) Regulations 2010 (as amended) and SEPA regulates disposals in Scotland under the Radioactive Substances Act 1993. EDF Energy is required to use “Best Available Techniques” in operating its nuclear power stations so as to minimise the production of radioactive waste and to minimise radioactive discharges to the environment. Discharges are closely monitored and reported to the environmental regulator.