text: The releases of fission products and uranium from uranium dioxide (from spent BWR fuel, burnup was 65 GWd t) which was heated in a Knudsen cell has been repeated. Fuel was heated in the Knudsen cell both with and without preoxidation in oxygen at c 650 K. It was found even for the noble gases that a high temperature was required to liberate them from the uranium oxide solid. For unoxidized fuel 2300 K was required to release 10% of the uranium while oxidized fuel only requires 1700 K to release 10% of the uranium.
  According to the report on Chernobyl used in the above table 3.5% of the following isotopes in the core were released Np, Pu, Pu, Pu, Pu and Cm.