2. Water chemistry. Materials

2.1 Radiolysis

The need to avoid deposits on the heating wall of fuel sheaths, along which boiling heat transfer takes place, leads to the search for water that is as pure as possible. This purity cannot shelter the water or its vapor from radiolytic decomposition, the phenomenon of dissociation of the H ₂ O molecule into nascent oxygen and molecular and atomic hydrogen. This dissociation is caused by high-energy gamma rays and neutrons, which are particularly dense in the core but also travel through the annulus to the vessel wall. This radiation also causes atoms to recombine, the apparent radiolysis being the difference between the two.

Simultaneously (via a neutron-proton reaction), neutrons transmute...