Thermodynamic modeling to facilitate safe handling of CsCl sealed sources

Sealed radiation sources containing CsCl have a chemical instability created by decay of 137 Cs to 137 Ba that creates a strong reducing environment inside the source. If exposed to air, strong exothermic reaction could result and may vaporize contents of the source. This study examines chemical equilibria inside sources before and after exposure to air to identify reactions involved and uncertainties due to decay time, temperature, impurity content, and cesium isotopic distribution. The overall goal is to present quantitative understanding that will inform safe handling and dismantlement procedures for sources.