Transmutation of radioactive waste by means of relativistic heavy ions

A series of experiments was carried out at the synchrophasotron of the Join t Institute for Nuclear Research (JINR), Dubna, using 3.67 GeV protons and 18 GeV C-12 ion beams. Two solid lead and uranium targets surrounded by par affin moderator were irradiated. The enter sur face of the moderator contai ned 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. Theoret ical estimations based on LAHET and DCM/CEM computer codes show considerabl y smaller fluences. A similar problem seems to appear in analogous experime nts at the Centre des Recherches Nucleaires (CERN), Geneva. In addition, lo ng lived radioactive waste nuclides, such as I-129 (T-1/2 = 1.57.10(7) a) a nd Np-237 (T-1/2 = 2.14.10(6) a), in the form of well-sealed tar gets (appr oximately I gram each) were placed in different geometrical positions durin g the 3.67 GeV proton ir radiations. The transmutation rates ale substantia l: a 10 mA, 3.67 GeV proton accelerator is able to transmute at least 30 % of Np-237 and 1% of I-129 per month, under the given geometrical conditions .