With sustainability and environmentally conscious business practices now the norm in most industrial fields, news of recycling materials is nothing new. But in the nuclear sector recycling isn’t simple. However, reusing materials from now decommissioned plants is becoming more popular. Penny Hitchin looks at the practice and some of the challenges that have had to be addressed.
Decommissioning creates large volumes of waste that must be characterised and dealt with appropriately. Applying the waste hierarchy – reduce, reuse, recycle – still sees much of the waste destined for secure disposal. However it is possible to decontaminate and recycle lower activity waste metal either by free releasing it onto the scrap market or using the decontaminated metal within the nuclear industry.
Decontaminating metal is a small niche market but one which has the potential to play a larger role as the pace of decommissioning picks up. The technology is well established and the nuclear supply chain has facilities for metal decontamination in Germany, Sweden, the UK, France and US. Recycling of contaminated metal from decommissioning has seen most deployment in Europe, notably in Sweden, Germany the UK and to a lesser extent Finland. Whilst the US does have metal recycling capability, plentiful availability of disposal capacity combined with a ban on free releasing decontaminated metal has made disposal an easier option.
Disposition of nuclear waste is highly controlled and governed by national and international regulations. Administrative procedures are rigorous and each metal recycling facility has defined waste acceptance criteria and is subject to restrictions on factors affecting the annual throughput, delivery, disposition and onward transport of radioactive waste.
In Germany the foundry technology division of engineering group Siempelkamp has been operating CARLA, its central plant for the recycling of low-level radioactive wastes, since 1989. The facility treats lower activity metallic waste by blasting (to remove surface contamination) or melting. Contaminated residues are recycled into resources for new products within the nuclear industry. If the requirements for release are met the metal can be released onto the open market. Both surface treatment and metal melting leave a small volume of radioactive residue, which is returned to the consignor for disposal. CARLA’s licensed capacity is 4000t per annum. Siemplekamp reports that in 2015 high volumes of metal from German and UK decommissioning projects led to record throughput and CARLA ran on a full load three shift operation.
The other main European facilities were developed by Swedish nuclear waste management company Studsvik. Its Swedish metal treatment and melting facility near Nyköping started operations in 1989. It has a licensed capacity of 5000t per year of which no more than 1000t can be lead. The technical capacity for the melting plant is around 8000t per year. As well as melting metal, it has unique facilities for treating large components such as steam generators and can treat aluminium and is seeking to treat galvanised metal.
In 2009 Studsvik opened a metal decontamination facility near Sellafield in the UK, the first new UK nuclear site to
be licensed in over 20 years. The UK site carries out surface decontamination with the objective of free releasing cleaned metal into the scrap market. The technical capacity of the facility is 3000t per year.
This facility receives a range of metal objects, ranging from former spent nuclear fuel handling equipment to filing cabinets. It can strip and treat cables, treat scaffold poles, and has had a successful campaign treating railway wagons. It decontaminates motors by disassembling and treating the components. If appropriate it ships metals to its sister plant in Sweden which as well as melting metal can treat very large components such as the Berkeley Boilers.
In summer 2016 Studsvik AB sold its Waste Treatment business and metal recycling facilities in Sweden and the UK to EDF Developpment Environnement for SEK 355 million (around €37 million). Studsvik put the 2015 turnover of the divested business at SEK 174 million (€18 million). The acquisition of these facilities, now called Cyclife, supplements EDF’s existing facilities at Socodei in France. It will serve European nuclear operators and enable the company to become a significant service provider in waste treatment and decommissioning in Europe and eventually further afield.
In the short-term the European demand for metal decontaminating services has lacked certainty as financial pressures have prevented acceleration in decommissioning progress. The market is likely to grow in the medium-term as the volume of decommissioning increases. Over the longer term, demand is likely to increase, notably because a large number of French nuclear power stations will move from operations into decommissioning, creating large volumes of waste which will require managing effectively.
In 2000 public concern about radioactivity led the United States Department of Energy (DOE) to suspend the unrestricted release of metal from radiological control areas regardless of radiological character. The suspension was originally imposed as a temporary measure while DOE improved its administration of radiological clearance and release policies
and requirements. Output had peaked in 1995 when 13,600t of carbon and stainless steel were recycled to general industry. This was less than one percent of the total radioactive scrap US inventory. DOE estimates that compliance with the policy resulted in a backlog of over 14000t of uncontaminated scrap metal at DOE sites by 2014 with a market value in excess of $50 million.
However, while decontaminating metal for free release is not permitted, there is a route for decontaminating and recycling metal for onward use within the nuclear industry. Low activity metal can be decontaminated and recycled to make shield blocks, waste containers, security barriers and shipping casks.
The main US metal treatment facility is EnergySolutions’ Bear Creek facility in Oak Ridge, Tennessee, which can process various types of radioactive waste. Its metal melting capability is used to process lead and other slightly contaminated scrap metal from decommissioning. Between 1994 and 2007 it processed 54 million kg of metal.
Over a five year period between 2000 and 2004 DOE recycled 710t of lead for use in shielding products and shipping casks, saving an estimated €2.5 million. This figure is based on the 2004 disposal cost for lead (including encapsulation in plastic) of €6/kg, compared with a recycling cost of approximately €3/kg.
The Electric Power Research Institute (EPRI) has supported development of two chemical treatments to decontaminate radioactive metal. The EPRI DFD and DFDX processes are treatments that can be taken onsite to remove contamination from radioactive metals. In the DFD process most of the contamination is taken up in ion exchange resins which become the waste form. The DFDX technology uses the same chemistry but instead of taking up contamination in ion exchange resins, they are electrochemically removed. Carbide electrodes absorb metal oxides and the carbon cells become the waste form.
The techniques were developed in the 1990s. Richard Reid, EPRI programme manager in the Fuels and Chemistry group, explains that the intention was to develop specific processes for use in situ with decommissioned metal components. They are built on processes used in operational plants but with no need to avoid a deleterious effect on the plant, the chemicals used to remove the decontamination can be more aggressive.
Full system decontamination has been done at a number of plants, rather than cutting each component down and shipping to an offsite facility. Decontaminating components at the plant means that typically they achieve a higher degree of decontamination. In-situ decontamination avoids the requirement to ship radioactive components.
In Europe, deployment of the EPRI mobile plant requires a permit to operate on a nuclear site, permit variations and submissions to the EU. Chemical decontamination has been performed in all European countries with active plant decommissioning projects. The DFD process has been used in the UK, Spain, and Germany and most recently in Slovakia, while alternative processes, notably the mobile CORD process that uses different chemistry, have been used in Sweden, the Netherlands, Italy and Germany.
Drivers for recycling
There is a consensus that low level activity waste can be disposed of in near surface secure facilities. The Czech Republic, Finland, France, Japan, Netherlands, Spain, Sweden, and UK each operate such a facility while the US has five.
Disposal is subject to nuclear and environmental regulation and radioactive waste disposal capacity is scarce and expensive. Gaining consent for new facilities is difficult. EU member countries are signed up to the EU Waste Framework Directive which came into force in 2010. The Directive sets out a waste hierarchy, a waste management principle that ranks waste management options (waste prevention, minimisation, reuse, recycling and, least preferred, disposal) according to their environmental impact. Waste producers are required to manage their waste in ways that minimise environmental impact, where practicable.
Decommissioning waste streams should be characterised and sorted in order to use best available techniques (BAT) in making decisions about their treatment and/or disposal. Size, reduction, compaction and incineration are some of the processes that may be appropriate. Cost, regulations, transport and availability of facilities are part of the equation.
While Japan Nuclear Fuel Limited operates a LLWR Disposal Centre at Rokkasho-Mura, Asia has limited disposal facilities and waste treatment options. China, Japan, Korea and Taiwan all face forthcoming decommissioning challenges. Asian nuclear operators are looking to Europe and the US for information on best practice and recycling through treatment to minimise disposal volumes. China has a track record of investing in foreign technology companies, and waste technology is an area that could be of interest.
Supply chain companies involved in waste management and waste treatment are also looking to Asia’s growing market. Studsvik and Kobe Steel Ltd have formed a new Japanese joint venture (Kobelco Studsvik) to provide radioactive waste management solutions to the Japanese nuclear industry. Kobe Steel has supplied the Japanese nuclear industry over many decades. One recent project was installing a new waste incinerator to support waste management at Fukushima Daichi. The joint venture will marry Studsvik’s experience in waste management, including its THOR* technology for radioactive waste treatment, and metal recycling along with Kobe Steel’s industrial and delivery capability in Japan.
As decommissioning ramps up, nuclear power operators across the globe will face the challenges of decommissioning and disposal. As decommissioning expertise builds, new and innovative approaches are likely to be developed. Russia is looking at possibilities for foam decontamination. German academics are studying the possibility of recycling rare metals like indium, niobium, vanadium, cobalt, or tin and rare earth metals. Decontamination and recycling of metals is a small niche market, but one that has the potential to grow. With its development of an integrated LLW policy, the UK has led the way in diverting waste from disposal. Regulatory, sustainability and economic drivers are likely to see decontamination and recycling of metal waste from decommissioning increase in the years ahead.
* THOR technology use steam reforming to immobilise radionuclides in organic and inorganic materials, forming a stable, water insoluble mineral matrix. It is suitable for plutonium contaminated materials, organics, liquids and graphite and can achieve significant volume reductions.