[en] A review on nuclear transmutation of radioactive wastes using particle accelerators is given. Technical feasibility, nuclear data, costs of various projects are discussed. It appears that one high energy accelerator (1500 MeV, 300 mA proton) could probably handle the amount of actinides generated by the actual French nuclear program

[en] The use of thorium as nuclear fuel in place of uranium opens interesting perspectives. This question is detailed especially from the point of view of radioactive waste management and their toxicity. (N.C.)

[en] Nuclear waste partitioning and transmutation (P and T) are considered in France as an official line of research, in accordance with the Law of December 30, 1991 concerning research in the field of long lived and highly active nuclear waste. A research group called GEDEON (GEstion des DEchets par des Options Nouvelles) has been set up between CEA, CNRS, EDF and FRAMATOME with the aim to carry out basic research related to the use of accelerator driven subcritical systems (ADS) and of thorium as an option to reduce the waste long term impacts. In the partners agreement of GEDEON, the following subjects have been identified: spallation physics, nuclear data, subcritical neutronic studies, materials, thorium, system and scenario studies. The organization as well as the scientific program and activities of GEDEON are presented

[en] An evaluation of present options to handle and store spent fuels from nuclear power plants is presented. Alternative of complementary options should be considered, e.g., transmutation, a method to transform long-lived nuclei into short-lived or less radiotoxic nuclei. Neutron appears as the ideal particle to induce these transmutations, called transmutation or incineration depending on the main route, capture or fission, resp. An overview of and technical options for transmutation are discussed in detail. (R.P.) 45 refs., 4 figs., 2 tabs

[en] A solenoidal detector is proposed in order to detect charged particles in a complete symmetrical way around zero degree. Used in a symmetric mode, this convergent lens is able to refocuse within a circle of diameter less than 0.8cm, the particles emitted at angles between 1⁰ and 10⁰ providing a large solid angle of about 95msr. Different uses are considered (angular correlation studies, angular distribution with good angular resolution and large solid angle, transfer of short-lived β emitters produced in heavy ion reactions). Typical geometries are calculated e.g.: length 150cm, internal diameter 21cm, max. field 4.10Teslas for β=1.5Txm, object-image distance 270cm). Such apparatus should use supraconducting techniques

[en] Optical properties: transfer matrix and acceptance of the electrostatic mirror have been calculated for any transit time value. Advantage of this type of inflector for axial injection into a compact cyclotron are discussed. Nevertheless one points out that the use of a mirror implies beam of very good quality, due to large transit time fluctuation related to the geometrical emittance. This is specially relevant to the case of the Orsay project, where one aims at a phase grouping of few R.F. degrees

[en] The time evolution of radiotoxicities of spent fuels and high-level wastes have been calculated up to 10⁷ years, in the framework of the recent I.C.R.P.-48 guideline, in which the ratio dose/ingested-activity has been divided by 10 for Np, multiplied by 10 for Pu and by 2 for Am, Cm and Cf, with respect to the previous I.C.R.P.-30 values. In the case of burn-up extension of the standard 33,000 MWd/t enriched uranium fuel, and in the case of plutonium recycle in light-water reactors, one shows that the spent fuel radiotoxicity is now dominated by its plutonium content, most of the time up to about 10⁵ years. Possible incineration effects are discussed within these two fuel cycle options

[en] Thorium extraction produces a certain amount of radioactive wastes. Potential long term radiological impact of these residues has been calculated using the recent ICRP-68 ingestion dose factors in connection with the computing code DECAY, developed at Orsay and described in this work. This code solves the well known Bateman's equations which govern the time dependence of a set of coupled radioactive nuclei. Monazites will be very likely the minerals to be exploited first, in case of an extensive use of thorium as nuclear fuel. Because monazites contain uranium as well, mining residues will contain not only the descendants of ²³²Th and a certain proportion of non-extracted thorium (taken here to be 5%), but also this uranium, if left in the wastes for economical reasons. If no uranium would be present at all in the mineral, the potential radiotoxicity would strongly decrease in approximately 60 years, at the pace of the 5.8 years period of ²²⁸Ra, which becomes the longest-lived radionuclide of the 4n radioactive family in the residues. Moreover, there is no risk due to radon exhalation, because of the very short period of ²²⁰Rn. These significant differences between uranium and thorium mining have to be considered in view of some estimated long term real radiological impacts due to uranium residues, which could reach a value of the order of 1 mSv/year, the dose limit recommended for the public by the recent ICRP-60. (authors). 15 refs., 4 figs., 3 tabs., 43 appendices

[en] In order to take into account new metabolic data, the International Commission for Radiological Protection (I.C.R.P.) had to regularly update the recommended values used for radiotoxicity definition and calculation. In the present work we compare the fuel radiotoxicity from different reactors and we study the impact of the changes in the I.C.R.P. recommendations on these radiotoxicities

No abstract available