For the nuclear industry, recycling metal waste is a relatively new concept. But following the opening of Studsvik’s metal recycling facility in Lillyhall, Cumbria, in September 2009, a new way of treating low-level radiological contaminated waste (LLW) began.
Studsvik MRF facility manager Mike McMullen says: “The strategy of the Nuclear Decommissioning Authority (NDA) has ensured that there is more emphasis on alternative disposal and recycling routes for the industry. In the past, this type of waste has simply been disposed of it at the Low Level Waste Repository (LLWR) near Drigg in Cumbria, a method which has embedded itself within the industry.
“Educating the sector about recycling and waste reduction during the past 12 months has been key, with a lot more metal now being redirected away from the LLWR than when we first opened.”
The decision to build a facility to manage LLW metal was an environmental consideration but also a strategic one. The NDA recognised that the LLWR, which is operated on its behalf, was rapidly filling up because of the amount of waste being produced and the fact that depositing it there was a tradition. The LLWR is anticipated to cover the industry’s disposal needs for at least the next 10 years, so any waste that can be directed for treatment away from it will protect capacity at the repository and potentially extend its operating life.
Studsvik’s MRF is seen as key in lengthening the LLWR’s lifespan. Since starting operations, it has been successful in diverting approximately 1,000 tonnes of radioactive metal waste from the LLWR, treating it thoroughly so that it meets the Radioactive Substances Act 1993 Substances of Low Activity (SoLA) Exemption Orders. This means it is able to enter the normal scrap metal stream for recycling.
McMullen explains that the treatment process is variable: “The length of time for the whole treatment process can take anything from one hour to three days, depending on the characteristics of the waste.”
First, the level of radioactivity of the metal is measured on delivery to the site, then it is sorted by type and size. The metal is cut up using hot and cold cutting technologies to ensure that it can fit into the grit blasting machines. “The metal is cleaned by using standard steel grit blasting techniques, which removes the surface contamination and coatings from the metal,” says McMullen. “Most of the radioactive contamination is on the surface of the metal or ingrained into surface coatings such as paint or rust (see images pre- and post-treatment).”
Metal that cannot be decontaminated at Lillyhall to meet the SoLA exemption level is transferred to a Studsvik plant in Sweden for further treatment, where it is put through a smelting process. “When the metal is melted, some nuclides will come off in gas and be captured in the filtration system and some will come off in the slag. The residues from grit blasting and smelting are eventually returned to the LLWR for final disposal,” says McMullen.
The Lillyhall site was the first to be granted a nuclear licence in 20 years in February 2008. According to McMullen, it took three years to obtain the licence and the associated regulatory permissions from the Office for Nuclear Regulation and the Environment Agency.
“One of the drivers was the shift in Government policy in waste management and recycling during the past few years, which formed the basis of the NDA’s strategy on LLW management,” McMullen explains.
The NDA developed and published its UK Strategy for the Management of Solid Low-Level Radioactive Waste from the Nuclear Industry in August 2010, following industry consultation (see below). And the 20-year breakthrough has meant some re-education in a long-established industry.
“Swapping disposal at LLWR for recycling of metal has been something of a culture change for the industry,” McMullen says. “There is a continuing need to further educate sites about recycling radioactive metal waste, reducing the need for disposal at the LLWR.”
The Studsvik facility has a 3,000 tonne a year capacity, and aims to recycle 95% of the metal it takes in by volume. This capacity is expected to be filled as the industry becomes more efficient in meeting the LLW strategy and recognises the economic case.
According to the NDA’s report: “In many cases, managing waste at a higher level in the waste hierarchy appears to cost more than disposal. But this is often because the true lifecycle costs of disposal are not easily recognised. Consideration of affordability should include the balance between the lifecycle environmental and social benefits of managing waste at higher levels of the waste hierarchy and the lifecycle cost of different management options, including disposal.”
In fact, there is estimated to be around 500,000 tonnes of waste metallics in the UK that need to be decommissioned, which will ensure that Studsvik has a huge amount of potential growth.
“Our plans for the future are quite fluid at the moment. Expansion of the facility will develop in line with the market and speed of release of wastes from nuclear sites. We have always aspired to have a smelting facility in this country at some point in the future,” McMullen says. But current market conditions preclude development along these lines at present.
The future of the site will be driven by a number of factors including changes to regulatory frameworks that currently allow Studsvik to ship metal waste to its plant in Sweden. If this route were to cease, this would necessitate the need for UK smelting capability for LLW metals.
Studsvik’s MRF currently offers a service to the UK nuclear industry, but it is clear that potential for growth is strong. This is especially so as the industry starts to apply the NDA waste management strategy and awareness of Studsvik’s recycling site grows. It may be early days for the MRF, but it seems that radioactive metal recycling has a glowing future.
LOW-LEVEL WASTE STRATEGY
The Nuclear Decommissioning Authority’s (NDA) document UK Strategy for the Management of Solid Low-Level Radioactive Waste from the Nuclear Industry aims to deliver a cost-effective, environmental framework to treat low-level radioactive waste (LLW). It does not set out to develop techniques and technologies, believing there is already sufficient capability in the UK at present.
The NDA set out key principles for the management of LLW, which encourage:
- Waste prevention should be implemented by all producers of LLW wherever practicable.
- Effective characterisation and segregation of waste, and material that will become waste, is critical to flexible management of LLW.
- Given the diverse nature of LLW, the availability of proportionately regulated waste management routes is essential.
- The development of new waste options or approaches to the management of LLW requires early and proactive engagement with local and national stakeholders.
- Availability of flexible waste management options is essential for hazard reduction and decommissioning and the continued operation of the nuclear and non-nuclear industries.
- Waste management decisions should be supported by sound business cases and demonstrate the use of robust decision-making processes to identify the most advantageous option.