TREATMENT OF RADIOACTIVE-WASTES BY PLASMA INCINERATION AND VITRIFICATION FOR FINAL DISPOSAL

Thermal plasma technology takes the advantages to incinerate the combu stible parts of radioactive wastes for volume reduction and to vitrify the noncombustible counter parts simultaneously into glassy slags wit h very low leaching rate. For developing the proper plasma processes t o treat various waste forms, a crucible-type plasma melter and a 10 kg h(-1) plasma furnace system are built at the Institute of Nuclear Ene rgy Research (INER). Both systems are fired by the home-made 100 kW no n-transferred plasma torches. The maximum operation temperatures of th e small plasma melter, and the 10 kg h(-1) plasma furnace are 1700 deg rees C and 1650 degrees C, respectively. Glassy or ceramic slags with high quality are obtained from the processing of simulated radioactive wastes by plasma torch. The compressive strengths of these slags are greater than 800 kg cm(-2), and the leaching indices of several elemen ts are between 8 and 15, which are all greater than the ROC regulated values for waste forms (i.e. 15 kg cm(-2) and 6). These promising resu lts encourage INER to further develop plasma system with higher capaci ty and plasma processes for the treatment of low level radioactive was tes. Future efforts shall be concentrated on the studies of system rel iability, secondary waste minimization and volatile radionuclides elim ination in off-gas. (C) 1998 Elsevier Science B.V.