Thermal stability of morpholine additive in the steam‐water cycle of CANDU‐PHW nuclear power plants

The thermal decomposition of morpholine, an additive used in the steam‐water cycles of nuclear power plants, was studied using a laboratory high‐pressure reactor. The measured decomposition rate constants are 2.67, 8.73 and 21.25 × 10 −7 s −1 at 260, 280 and 300°C respectively. The kinetics were found to be first‐order and the activation energy was 131.9 kJ/mol. Ammonia, ethanolamine, 2‐(2‐aminoethoxy) ethanol, methylamine, ethylamine, ethylene glycol, and acetic and glycolic acids were identified as the major breakdown products. The decomposition route proposed was validated in the field by tracking these breakdown products in water samples taken at Gentilly 2 power plant.