The use of thorium for plutonium utilization in reactors

cycle with a full-scale use of thorium is only a far perspective for Russia. Resources of uranium for NPPs with thermal neutron reactors will be sufficient for decades in Russia and involvement of fast neutron reactors into power system makes the problem of raw resources less actual. However, in Russia research works on uranium-plutonium cycle were closely followed by those on thorium-based one. Of course scales of those research works were incomparable. But recently the peculiarities, problems, and perspectives of thorium-based cycle have been discussed more actively in Russia and abroad. Besides, experts have realized that application of thorium-based cycle, at least in the nearest future, will be most probably evolutional, which does not demand any radical changes in the existing fuel cycle. At the same time, some useful features of thorium can be used in a short term. The possibility of using thorium in the process of plutonium utilization is one of such useful properties; in this case, unlike MOX fuel, the plutonium breeding is excluded. The feasibility to include plutonium and thorium into a fuel cycle of Russian light-water reactors WWER-1000 is also touched upon in this report. Once-through fuel recycle has been considered, the final decision on its further utilization being postponed. Basic fuel parameters and properties, important from safety standpoint, are presented. The minimum changes in the structure necessary to ensure safety of plutonium-thorium fuel at the level of conventional WWER-1000 are needed. A wide range of problems investigated and to be investigated is outlined in the paper. (author)