Nuclear energy is at the forefront of many scientific minds these days. The Fukushima crisis shined a spotlight on possible dangers associated with the locations of nuclear plants, as well as the logistical and human health nightmares that can occur with meltdowns. But these aren’t the only concerns about nuclear power on which scientists are focusing. Nuclear waste management is also actively perplexing engineers, policy-leaders, and decision-makers, as the concern over how to best dispose of High Level Waste (HLW) continues to grow.
The US Nuclear Regulatory Commission (NRC) defines HLW as “the highly radioactive materials produced as a byproduct of the reactions that occur inside nuclear reactors.” HLW takes two forms: Spent or Used reactor fuel (SNF/UNF) when it is accepted for disposal, and waste materials remaining after spent fuel is reprocessed. According to the NRC, “spent nuclear fuel is used fuel from a reactor that is no longer efficient in creating electricity, because its fission process has slowed. However, it is still thermally hot, highly radioactive, and potentially harmful.”
Most experts concur that deep geologic repository is the only safe solution of the storage of SNF/UNF and HLW. The US had plans for deep geological repository in Yucca Mountain until 2010 when these efforts were stalled indefinitely. But while the US and many other parts of the world languish without a concrete long-term solution as to how to store HLW, Europe has been very proactive. According to Irena Mele, a nuclear physicist who heads the Waste Technology Section in the Department of Nuclear Energy of the International Atomic Energy Agency (headquartered in Vienna), “Europe is really making good progress in this area. We have very clearly structured programs for all sorts of waste.” She and various agency leaders discussed Europe’s headway during the WM Symposium 2012, an international conference on nuclear waste management held 26 February to 1 March in Phoenix, Arizona, USA.
Mele stressed that outside of Europe, very few countries have operating repositories or plans for them. In fact, in Africa, only South Africa has a repository programme in place. One of her major concerns is related to “newcomer countries” (nations that are just beginning to establish a nuclear energy programme), where disposal of waste is a big challenge. “Their main focus has been on power needs and nuclear power plant construction,” she said. “Little consideration is spent on spent fuel and waste management needs.”
According to the European Nuclear Society, there are currently 187 nuclear power plant units with an installed electric net capacity of 162 GWe operational throughout the continent. France leads the list with 58 plants, followed by the Russian Federation (33), UK (18), Ukraine (15), and Sweden (10). An additional 18 plants are under construction. In addition to waste produced by power plants, nuclear waste is also produced by laboratories, universities and hospitals, although in much smaller amounts.
At one session during the conference, representatives from the Netherlands, Belgium, and Spain highlighted their milestones and successes in their continuous quest to develop concentrated, collaborative strategies for deep repository with realistic goals, timelines, deliverables and even budgets.
In The Netherlands, although its citizens do not yet have a repository, they have interim storage solutions, and a framework that will allow for a “dual-track” programme for repository planning. Hans Codee, a chemist with CONRANV, the Dutch nuclear waste management agency, explained that the two tracks consist of a national agency aligning with a regional organisation to investigate and develop novel solutions. You have to think beyond nations, he advised, because borders can always change. “You have to set up a credible, robust programme that shouldn’t change [according to politics]. Waste management is a long-term management scheme and you have to be reliable and 100% transparent.” Funds should be allocated now, he added, so that future generations will already have everything in place when the interim solutions are no longer viable. “We are altogether responsible for it.”
He and his team are looking at numerous options for deep repository in clay and salt reservoirs, both beneath the land of the Netherlands, as well as beneath the water of the North Sea. “In principle, this is normal mining,” he described, “It is funny that you restrict yourself to ‘on land’ situations. Why would you do that when there’s more water then land? And in The Netherlands, we have to be very, very careful with what we do with our land.” One idea they are exploring, he noted, could be to make artificial islands, and then use the above land space for windmills or airfields. “It is not so complicated to deal with something under water,” he concluded.
The Belgian Agency for Management of Radioactive Waste and Enriched Fissile Materials (ONDRAF/NIRAS), together with the Belgian Nuclear Research Centre (SCK•CEN), has been formally researching possible deep repository solutions since 1974. Scientists have analysed various geological formations that can be utilised, including clay settings, and in 1980 began the construction of HADES, a cutting-edge underground laboratory in Boom clay at a depth of 224 meters. Through the years, many experiments have been conducted at HADES, but according to Marc Demarche, the Deputy General Manager of ONDRAF/NIRAS, the most important outcome has been the ability to demonstrate that an underground facility of this kind could be constructed in this type of clay. As noted on SCK•CEN’s website, “The building of the underground laboratory demonstrated that it is technically feasible to dig out shafts and galleries in a plastic clay layer. Moreover, the excavation techniques have continuously been improved during the successive phases and methods have been developed to minimise the disruption of the clay formation.”
Demarche stated that his country “has it in our law that we have to have a long-term management plan for radioactive waste.” Their specific programme requires an environmental impact assessment and public participation, he continued. As written on SCK•CEN’s website (and clarified by Demarche), “in a next phase of the Belgian research programme, the possibility of geological disposal will be demonstrated on true operation scale. Thereto, a demonstration test (PRACLAY) is planned, in which the behaviour of the disposal system is examined on true scale and at temperatures that are equal to those applied for the disposal of vitrified highly active waste.” This includes analysing potential waste containers, including one that Demarche refers to as a “steel envelope with cement fill,” that has the potential to contain radioactive waste for 2000 years.
Spain has also achieved targeted milestones in regards to its nuclear waste management programme. With 20% of the nation’s electricity produced by nuclear plants, the government has been very vigilant regarding its responsibilities to ensure safe repository of radioactive waste, shared Mariano Molina of Enresa, the public company in charge of the safe management, storage and disposal of the radioactive waste produced. Enresa was launched in 1984 by Spanish Parliament, and by 1987, had already designed its first radioactive waste management plan, noted Molina. In 2011, a centralised storage site was designated for spent fuel, an important step towards long-term repository, and by 2017 this unit will be operational, he continued. “The process to get the central storage facility was not only a major programme for us, but it also gave us a lot of information as to how to move forward with the underground [long-term] storage goal.” Research and development is currently being directed towards the development of the repository solution, which includes trying to understand long term behavior of spent nuclear fuel, he said.
A version of this article appeared in the WM2012 Insight Newsletter, 1 March 2012.
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