Waste management

When used nuclear fuel is removed from the reactor it is highly radioactive, and requires proper shielding and careful handling to protect humans and the environment. Although radioactivity decreases with time, nuclear fuel remains a potential health, safety and security hazard for thousands of years - some say indefinitely. The world has to deal with a legacy of tens of thousands of tonnes of highly radioactive waste.

The nuclear industry broadly supports deep geological disposal as the preferred approach to managing the waste. Notwithstanding considerable research about the science, technology and engineering of possible storage and repository approaches over many years, the task of implementation has proven challenging. While repositories are in operation for disposal of low-and intermediate-level wastes in certain countries, no country has yet begun to store used fuel from commercial plants in permanent repositories. Some nations have declared, or even legislated, that a deep geological repository that isolates and contains used nuclear fuel is the appropriate approach. In addition others reprocess waste, partially to reduce waste volumes. They also provide waste reprocessing services to other countries. Transmutation technologies are the subject of extensive research in France.

While Finland has begun detailed rock characterization studies for its underground repository at Olkiluoto, and Sweden is well on the path to choosing between two possible sites for disposal, the controversial chosen site in the US - Yucca Mountain - has been delayed on technical grounds and because of local opposition. These delays have resulted in lawsuits and financial penalties. Several countries (the UK, France and Canada) have just completed reviews of the waste management options, while others have not yet decided on a path forward. In the interim, usually spent fuel is immediately stored in water pools and later, after cooling for five to ten years, moved to interim storage in dry casks on site. Internationally, there have been some discussions about regional and international repositories to ease the cost burden on smaller countries.

Future technological developments might change the balance of risks. Advanced closed-fuel cycles separate or partition plutonium and other actinides, transmuting them into shorter-lived and more benign species. The goal is to reduce waste heat, increase the storage capacity of the repository and shorten the required waste isolation time. Debate continues as to whether or not these potential benefits outweigh the incremental costs, short-term safety and environmental risks.

Over the past decade a number of national waste management programmes have had to be reigned in and rethought, put on hold, or even abandoned in the face of public opposition and activist electorates. Radioactive waste decisions, once considered the exclusive purview of governments and the nuclear industry, are now clearly in the public domain. The analyses in Canada (National Waste Management Organization, 2005) and the UK were based on legacy wastes and explicitly say that the creation of new wastes involves ethical considerations that should be part of a wider discussion about the future of nuclear. Technically, new waste could be accommodated with an increase in the size and cost of the facility.

The time dimension of managing nuclear waste is a key ethical issue. Effectively, we are being asked to develop public policy that would require implementation over a period longer than recorded history. Given the longevity of the hazard, it is imperative that obligations to future generations are considered explicitly. Managing nuclear waste requires a great margin of safety, as damage would be multigenerational and irreversible. While the probability of an event may be low, the consequences could be high. Technically, the waste problem may be manageable. But any approach has to be, and be perceived to be, robust under all scenarios.

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