Spent nuclear fuel is removed from the reactor when it can no longer con­tribute to the fission energy process, typically after three to seven years use. The fuel, however, still contains components, uranium and plutonium, that could be reused and recycled as fuel material. As for most waste in our society, e. g. paper and glass, there is, however, an economic issue involved in the decision to recycle or not. Although the remaining uranium and plutonium can be recycled as mixed oxide fuel (MOX) in present-day light water or heavy water reactors, real benefit from recycling will only be achieved if the fuel is recycled in fast spectrum reactors, so called fourth- generation reactors, which are being developed now. There are thus two options for spent fuel management:

• regard the fuel as a waste and dispose of it in a deep geological reposi­tory after a period (>30 years) of interim storage for sufficient cooling, or

• reprocess the fuel to separate out the components that can be recycled as fuel material after a period (~10 years or less) of interim storage. The remaining waste products (HLW and ILW) will still need geological disposal.

Some countries, e. g. Canada, Finland, Germany and Sweden,[82] have chosen the direct disposal route, while other countries, e. g. France, India and Japan, have chosen the recycling route. Most countries, however, have still not decided which option to choose. As spent fuel storage for decades is a straightforward and proven technology, there is no urgent technical need to make the choice. Prolonged storage will provide time to consider the progress in fast spectrum reactors with effective recycling, and provide a better basis for making the choice. Storage times of 100 years and more are now considered in some countries. As both options will in the end require a deep geological disposal facility, it will be important to work towards the development of such a facility, not least from a political acceptability point of view.

The views on reprocessing or direct disposal have changed over time. Some countries, e. g. Germany and Sweden that in the 1980s sent fuel for reprocessing, changed their policy in the 1980s to storage and subsequent disposal. Also in the USA the position has changed over the years. Reprocessing was the main option early on and some civilian reprocessing plants were built. Since the early 1980s the main option has been direct disposal, and investigations for developing a disposal facility at Yucca Mountain in Nevada were conducted up to the point that a licence applica­tion was submitted to the US Nuclear Regulatory Commission in 2008. This application was later recalled in 2010. In parallel, studies were conducted on reprocessing and recycling in fast reactors. In 2009 a Blue Ribbon Committee was set up to advise the Administration on the way forward. The result of the Commission is due in 2012.

The steps for spent fuel management include interim storage, reprocess­ing and subsequent recycling of fuel material and conditioning of the remaining waste for disposal, or encapsulation of the fuel for disposal, and final disposal. As the facilities involved are normally located at different locations, transport will also be needed. Interim storage can be made in pools in the reactor facility or in separate storage facilities, containing either water pools or dry casks or vaults (Fig. 14.1). Given the trend towards longer storage times, there is also a trend towards using dry storage systems that can be built in modules as the needs arise and that will require less active operation. There is also a trend towards primarily expanding the storage capacity at the reactor sites to avoid extra transport.

Reprocessing facilities and facilities for producing MOX fuel exist today in only a few countries — France, India, Japan, Russia and the United Kingdom. These facilities need to be quite large and involve technology that is sensitive from a nuclear proliferation point of view. It can thus not be expected that they will be built in many countries. The existing facilities have served nuclear utilities in several more countries. In most cases the wastes from reprocessing, HLW, ILW and LLW, have been returned to the country of origin for storage and disposal.

So far no country has started disposal of spent fuel or high-level or intermediate-level waste in deep geological repositories. Development work is underway in several countries and good progress can be seen in Finland, France and Sweden, countries that expect to start disposal in the period 2020-25. Although the technology for disposal is fairly straightfor­ward and simple, the safety assessment poses important challenges, as the time periods to be considered are very long (from thousands to hundreds of thousands of years). Another important challenge is the public and politi­cal acceptance of disposal. Important setbacks have been experienced in many countries, which has delayed the disposal projects and led to impor­tant changes in the siting process. Experience has shown that the time needed for developing a deep geological disposal facility, including the time needed for scientific studies and siting, is at least 40 years.

More technical details of the different steps for spent fuel management are given in Section 14.4.