Observations on the Release of Caesium from UO2 Fuel

Abstract

Caesium is probably the most important fission product created during the irradiation of nuclear fuel. The relatively high fission yields of the stable and long-lived isotopes of Cs , the low boiling point of Cs (670*C) and the low dissociation temperature of its oxides (<700*C), the high gamma reactivity of 137-Cs with a half-life of 30.7 years, and the high chemical reactivity of Cs dictate that its behaviour is considered in all aspects of the nuclear cycle. In the context of nuclear fuel performance Cs is second in importance only to xenon. Because of its low solubility, generally a high percentage of Cs is released from the fuel grains during a reactor power excursion.