Burn-up determination of mixed-oxide fuels using TIMS

The term burn-up is used to denote the atom present fission of heavy elements (mass >225). Mixed oxides consisting of a homogenous solution of (UO2+PuO2) have been proposed as a substitute to enriched uranium used in boiling water reactors. Determination of nuclear fuel burn-up is important for fuel management, fuel development, fuel performance evaluation and for validation of computer codes. The atom percent fission is obtained from the concentration of a suitable fission product isotope (burn-up monitor) relative to those of heavy element isotopes. The method for the experimental determination of burn-up involves the dissolution of fuel sample, separation of U, Pu and burn-up monitor and their concentration determination. The concentrations of the heavy elements and those of burn-up monitor were determined by isotope dilution mass spectrometry (IDMS) in order to circumvent the problems associated with quantitative separation and handling of radioactive samples. ID-TIMS provides the most reliable and accurate data for the concentration determination