Drop calorimetric measurements on a versatile monazite phase loaded with simulated radioactive waste

作者：Asuvathraman R^*; Joseph Kitheri; Joseph Jose; Krishnaiah M V; Kutty K V Govindan

来源：Journal of Thermal Analysis and Calorimetry, 2014, 117(3): 1151-1156.

DOI：10.1007/s10973-014-3873-5

• Monazite
• Isoperibol drop calorimeter
• Enthalpy increments
• Heat capacity
• HLW
• Radioactive waste
• Nuclear waste immobilization

Monazite is one of the candidate ceramic matrices for the immobilization of high level radioactive waste (HLW) from the reprocessing of spent nuclear fuel. The monazite phase, Ce0.8Ca0.2PO4, can accommodate cations of different valences due to the mixed valence state (+3 and +4) of Ce in this compound, by facilitating the oxidation and reduction of the Ce3+ and Ce4+ as required by the in-coming cation. This will assist in accommodating HLW of different compositions in the monazite crystal structure even if the average valence of the HLW elements is other than 3. Therefore, the monazite phase, Ce0.8Ca0.2PO4, can be a versatile host for the immobilization of HLW. The enthalpy increment and heat capacity of this versatile monazite phase and a simulated waste form based on it with 20 mass% HLW oxides were measured by drop calorimetry in the temperature range from 373 to 873 K, and the results are compared with those measured for CePO4.

• 出版日期2014-9