Transmutation of radioactive waste by means of relativistic heavy ions

A series of experiments was carried out at the synchrophasotron of the Joint Institute for Nuclear Research (JINR), Dubna, using 3.67 GeV protons and 18 GeV (12)C ion beams. Two solid lead and uranium targets surrounded by paraffin moderator were irradiated. The enter sur face of the moderator contained a number of small U and La sensors, and also solid-state nuclear track detectors Both experimental techniques identify independently approximately 28 low-energy neutrons per 3.67 GeV proton hitting the Pb tal get. Theoretical estimations based on LAHET and DCM/CEM computer codes show considerably smaller fluences. A similar problem seems to appear in analogous experiments at the Centre des Recherches Nucleaires (CERN), Geneva. In addition, long lived radioactive waste nuclides, such as (129)I (T(1/2) = 1.57.10(7) a) and (237)Np (T(1/2) = 2.14.10(6) a), in the form of well-sealed tar gets (approximately I gram each) were placed in different geometrical positions during the 3.67 GeV proton ir radiations. The transmutation rates ale substantial: a 10 mA, 3.67 GeV proton accelerator is able to transmute at least 30 % of (237)Np and 1% of (129)I per month, under the given geometrical conditions.