Processes are developed for the immobilization of radionuclides by solidification of radioactive wastes. The resulting solidifica-tion products are characterized by strong resistance to leaching aimed at low release r?tes of the radionuclides to the environ-ment.
To measure this resistance to leaching of the solidified materials : glass, glass-ceramics, ceramics, bitumen, cement, concrete, plastics, a long-term leach test is presented.
The long-term leach test is aimed at :
a) the comparison of different kinds or compositions of solidified waste forms;
b) the intercomparison between leach test results from different laboratories on one product;
c) the intercomparison between leach test results on pro-ducts from different processes.
The test temperatures will cover a sufficient range to give an in-dication of leaching behaviour at temperatures up to 90 °C. The test temperatures are chosen to be 313 K (40 °C), 343 K (70 °C) and 363 K (90 °C).
It is not required to carry out tests in all possible combinations of variables but one set of standard conditions should be met in order to assure interlaboratory comparability of the results. These conditions are :
A. HLW forms (see 3.1.1) and cement or concrete specimens (see 3.1.2); leaching in deionized water at 40 °C and 70 °C, for 1, 3, 7, 10, 14, 21 and 28 days. Three matrix elements and three waste constituents must be analysed.
B. Bitumen and plastic specimens (see 3.1.3); leaching in deionized water at 40 °C for bitumen and 40°C and 70 °C for plastics for 1, 3, 7, 10, 14, 21 and 28 days. At least three important waste constituents must be analysed.