Radioactive Waste ManagementPublished on 09.07.2015
10 min read
The management of radioactive waste presents unique challenges because the radioactive materials cannot be recycled. Contrary to popular belief, the nuclear industry is not responsible for all radioactive waste. In France for example, 38% of radioactive waste is produced by the national defense, research and medical industries. generation accounts for the remaining 62%.
© Cigéo, a planned radioactive waste storage center in eastern France, will be situated 500 meters below ground in a layer of clay that can contain the radioactivity. AFP PHOTO / JEAN-CHRISTOPHE VERHAEGEN
Different types of waste
In France, nuclear waste is classified into five categories based on two main criteria: the radioactivity level and longevity (radioactive half-life) of the waste1 .
- Very-low-level waste (VLLW) comes from the maintenance and dismantling of nuclear facilities and includes earth, rubble and scrap metal. It has a radioactivity level equal to that of naturally occurring radioactivity (less than 100 becquerels per gram – Bq/g) and is treated as conventional waste in some countries. VLLW represents 27% of the total volume of French radioactive waste, but less than 0.01% of its total radioactivity.
- Low and intermediate level short-lived waste (LILW-SL) with a half-life of no more than 31 years, is produced by operations in nuclear facilities and includes tools, gloves and masks. LILW-SL has a radioactivity level of between several hundred and one million Bq/g and represents the majority of French radioactive waste (63%) in volume, but only 0.02% of its total radioactivity.
- Low-level long-lived waste (LLW-LL) comes from first generation nuclear reactors that are now being dismantled. It contains elements such as graphite or and represents 7% of the total volume of French radioactive waste and 0.01% of its total radioactivity.
- Intermediate-level long-lived waste (ILW-LL) is composed of components of nuclear reactor structures and has a radioactivity level of between one million and one billion Bq/g. ILW-LL represents 3% of the total volume of French radioactive waste and 4% of its total radioactivity
- High-level waste (HLW) is the residue from the processing of spent nuclear and is produced in small volumes. All the HLW ever produced by the French nuclear industry would fit into a 13m-high cube. However, it represents 96% of the total radioactivity of French radioactive waste, as it has a radioactivity level of several billion Bq/g.
Conditioning and storage
Very-low-level waste – a category that is specific to France – is easily conditioned and stored. It is packaged in "big-bags" and covered with soil. In France, they are stored in layers at the Morvilliers facility in the northeastern part of the country.
Low and intermediate level short-lived waste is compacted, placed in metal containers and embedded in concrete. In France, they are stored a few kilometers from Morvilliers, at the Soulaines facility.
Conditioning low-level long-lived waste presents no technical difficulties. However, its long-term storage, ensuring that it is safely stored and monitored for several thousands of years, is far more problematic. For the moment, this waste is kept at nuclear sites such as Marcoule in France2. It is interesting to note that some chemical waste, such as mercury or arsenic, remain toxic forever.
The conditioning and storage of the two remaining categories (intermediate-level long-lived waste and high-level waste) is far more sensitive because they are both extremely hazardous and have very long half-lives. These wastes are vitrified – incorporated into molten glass – to ensure their containment long into the future. The glass is poured into stainless steel containers and stored in France in ventilated pits at the center at La Hague. No radioactivity is released from the containers, but they are closely monitored in what are called "warehouses".
What should be done in the very long term, bearing in mind that the radioactivity level of intermediate-level long-lived waste and high-level waste takes thousands of years to decline significantly? One option under consideration is deep underground storage in geologically suitable areas where clay or granite prevents water infiltration. Such solutions are subject to national legislation in countries around the world. France’s national radioactive waste management agency (Agence nationale pour la gestion des déchets radioactifs –ANDRA), an independent public establishment, is working from its underground research laboratory near the northeastern municipality of Bure on the Cigéo project to develop a deep geological disposal facility. The United States has initiated a deep geological storage facility project at Yucca Mountain in Nevada, but it has not been completed.