RD&D-Programme 2004 - SKB

• Partitioning of long-lived radiotoxic elements from spent nuclear fuel can be done in
additions to existing reprocessing plants. But a great deal of work is required to develop
the new processes from laboratory to industrial scale.
• Transmutation with fast neutrons is more effective than in existing light-water reactors.
Transmutation of transuranics can best be achieved in fast reactors or in accelerator-driven
systems with a fast neutron spectrum.
• Partitioning and transmutation will not eliminate the need for a deep geological repository
for certain long-lived radioactive wastes from spent fuel.
In the USA, some interest was aroused in transmutation with accelerator-driven systems in the
early 1990s. The centre of this interest was Los Alamos National Laboratory, which introduced
the concept of ATW (Accelerator-driven Transmutation of nuclear Waste). This eventually led
to a study of ATW by the US Department of Energy at the request of the Congress. The study,
published in the autumn of 1999 /23-7/, proposed a research programme for ATW that could be
the start of a large-scale investment in such a system. Certain portions of this work have since
been started, in particular those portions involving international cooperation. The programme
as a whole has, however, not been accepted as a basis for American research on advanced
nuclear fuel cycles or a future nuclear waste strategy. It was probably not intended as a complete
programme either, but rather as more of an in-depth evaluation of one of many possible
scenarios for the development of partitioning and transmutation.
In 2003, the USA announced the so-called Advanced Fuel Cycle Initiative (ACFI), which was
aimed at a broad study of the fuel cycle for future nuclear power reactors – also known as
Generation IV reactors /23-8/. This initiative is planned to consist of three phases: Phase I Basic
Technology Evaluation; Phase II Proof of Principle (5–6 years); Phase III Proof of Performance
(15–20 years). The programme is broadly conceived and includes a review of all current
systems, reactor types and partitioning methods.
After an initiative by the research ministers in France, Italy and Spain, a European technical
working group – TWG – was formed in 1999. This working group proposed a roadmap for
development of an accelerator-driven system (ADS) in Europe. The report from TWG was
published in the spring of 2001 /23-9/. The ambition from the group was that the roadmap
should form the basis for continued EU-funded research on ADS. The roadmap proposes
construction of a small experimental plant with an ADS of about 100 MW thermal power. The
plant is envisaged to start operation in 2015. The cost for the first twelve years of research and
development plus design and building is estimated at 980 million euro. In addition, another
180 million euro is proposed for R&D on nuclear fuels suitable for ADS. This first phase would
then be followed by a second where a prototype for a full scale ADS is developed and built.
After successful operation of this prototype for several years, industrial plants could begin to be
built in around 2040. This study is in fairly good agreement with the US DOE study in terms of
the projected schedule. In their details, however, the two studies have considerable differences.
The American study has a much more specific choice of systems for both partitioning
(pyrochemical process) and transmutation (ATW cooled by liquid lead-bismuth eutectic
mixture) than the European one. The latter is defined as transmutation with ADS, but keeps
several parts of the ADS open for later choice of design: accelerator, coolant, etc.
The work within the OECD/NEA continued within another expert group, which published a
comparative study of fast reactors and ADS for transmutation in the spring of 2002 /23-10/. The
group went through a number of strategies for partitioning and transmutation of transuranics
based on light-water reactors, fast reactors and accelerator-driven systems. Among the general
conclusions in the report are the following:
• While P&T will not replace the need for a deep repository for high-level waste, the study has
confirmed that different transmutation strategies could significantly reduce (by a hundredfold
or more) the radiotoxicity of the waste that must be emplaced in such a repository. This
improves the environmental friendliness of the nuclear energy option and could contribute to
a sustainable nuclear energy system.
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