RD&D-Programme 2004 - SKB

• Very effective methods for transmutation in fast reactor spectra and for multiple recycling of
the nuclear fuel with very low losses would be required to achieve this objective.
• Multiple recycle technologies that manage Pu and other transuranics either together or
separately could achieve equivalent reduction factors for the radiotoxicity of wastes to be
disposed.
• Pyrochemical reprocessing techniques (partitioning) are essential for fuel cycles containing
fuels with a very high content of americium and/or curium that are burned in ADS or fast
reactors.
• In strategies where plutonium and other transuranics are managed together, the choice
between ADS and fast reactors must be based on economic, safety and other considerations.
• In strategies where plutonium and other transuranics are managed separately, plutonium can
largely be burned in conventional (light-water) reactors, minimizing the need for ADS and/or
fast reactors.
• Further R&D on fuels, recycle, reactor and accelerator technologies would be needed to
deploy P&T. The introduction of transmutation systems would probably occur incrementally
and at a pace geared to national situations and policies.
• Fully closed fuel cycles can be achieved with a relatively limited increase in electricity cost
of about 10 to 20 percent compared with the LWR once-through fuel cycle.
• The deployment of these P&T schemes requires a long lead time to develop the necessary
technology and make it cost-effective.
Some of the more important technical conclusions from this study are:
• To achieve the goal of reducing the amount of long-lived radionuclides in the waste by a
hundredfold or more, the losses in each partitioning cycle must be less than 0.1 percent.
• Transmutation of plutonium alone will reduce long-term radiotoxicity by only a factor of
five compared with spent fuel.
• Transmutation can be achieved either by fast reactors or by different combinations of
light-water reactors, fast reactors and accelerator-driven systems.
• Due to physical limitations, a long time is needed to carry out a complete transmutation.
This means that the indicated goals can only be achieved if the technology is used for at least
100 years.
• The use of pyrochemical methods for partitioning involves new potential chemical and
radiological risks that must be mastered.
• All transmutation strategies for light-water reactors produce considerable quantities of
depleted and irradiated uranium that must be disposed of.
• Transmutation of long-lived fission products involves many technical and practical
difficulties. At present, technetium-99 and possibly iodine-129 appear to be the foremost
or perhaps the only candidates.
• Experimental research on transuranium fuel is a highly prioritised area. A bottleneck for such
research is the availability of facilities with a high fast neutron flux.
• The basic research and development on fast reactors as well as accelerator-driven systems
would be simplified if better agreement was obtained on the advantages and disadvantages
of different coolants for such systems.
Current research on partitioning
The so-called Purex process, which is used in existing reprocessing plants, uses phosphorusbased
organic compounds as extractants. A drawback with these is that they produce considerable
amounts of intermediate-level waste, which is contaminated with long-lived radionuclides.
310 RD&D-Programme 2004