Leaching of 137Cs from Chernobyl fuel debris: corium and “lava”

Samples of Chernobyl fuel debris such as corium and "lava" had been studied using repeated static leach test MCC-1 at temperature of 25 and 90 degrees C in distilled water and simulated seawater. A normalized Cs-137 mass loss (NLCs) estimated for corium samples after 168 days in distilled and seawater was 3.2-3.5 g/m(2) at 25 degrees C and 113-114 g/m(2) at 90 degrees C. For "lava" samples NLCs varied from 1.4 to 13.2 g/m(2) at 90 degrees C for 56 days (in distilled and seawater) and from 0.1 to 0.4 g/m(2) at 25 degrees C in seawater for 140 days. Chemical durability of Chernobyl "lava" in distilled and seawater evaluated using (137)(specific activity in leachates is higher than one for corium. Further study is proposed in order to obtain more quantitative data.