Partitioning and transmutation

How can the management of radioactive materials and waste be optimised? One possible route is to transmute the long-lived radionuclides that they contain, in order to reduce the duration of their radiotoxicity. The law of 28 June 2006 provides that "The corresponding research and development [on partitioning and transmutation] is being conducted in relation with that conducted on the new generations of nuclear reactors mentioned in article 5 of law 2005-781 of 13 July 2005 on the programme setting the orientation of energy policy, as well as that conducted on accelerator-driven reactors dedicated to waste transmutation, so that we will have an assessment of the industrial prospects of these technologies in 2012 and we will be able to put into operation a prototype facility before 31 December 2020".

Indeed, the long-lived radionuclides contained in the waste are responsible for the persistence of radioactivity for hundreds of thousands or even millions of years. Reducing the quantity of these radionuclides in the waste may therefore create greater scope to reduce the "source" term, improve the safety of the disposal facility, and significantly reduce its duration and even its area. These points should not be neglected, particularly with regard to acceptability, insofar as radioactivity should decrease considerably. However, they have significant implications for the industrial strategy, both on the type of reactors to be implemented and on the time of their implementation.

The R&D conducted in several countries, particularly in France, conducted by the CEA, has shown that the partitioning and transmutation strategy could only be effectively implemented by recycling plutonium and all or some of the minor actinides in fast neutron reactors (FNRs).

We can show that, if we were to recycle the plutonium and minor actinides, it would only take 500 years for the radioactivity of the waste generated by the reactors to return to the level of the natural uranium used as the fuel.

If we were to exclude plutonium, americium and curium from the waste, the thermal power of the waste to be disposed of would become much lower after approximately a century of storage.

The implementation of such a strategy, with the knowledge we have at present, would lead to heavier and more complex assemblies than those currently used: in particular, there would be a noticeable increase in the number of steps in the cycle operations and in radiation protection requirements. It would also still be necessary to make an economic assessment of this new approach.

All these studies remain theoretical, or are based on experimentation conducted on research reactors; industrial feasibility must be examined with the aim of optimising the nature of the final waste to be disposed of. The construction of a prototype fast neutron reactor, such as Astrid, is provided for in the abovementioned law. Such a prototype should allow some of the necessary studies to be performed.

The Board considers that the research efforts already undertaken must be maintained and deepened. If this condition is met, the deployment decisions to be taken between 2030-2040 on future reactors, cycle plants, storage and disposal can then be based on the best scientific and technical studies.