Energy From Thorium Discussion Forum

Why is this so? I can see heavy water and light water making a difference, but why should the pressure make such a difference to tritium production?

Most of the PWRs use boron to control the reactivity (while the BWRs don't use it). The boron is added in the primary coolant in the form of boric acid. This acidifies the water.

In order to get a a neutral pH they add LiOH to the primary water (LiOH rises the pH), so there are Li atoms in the water. The boron atoms also make 7Li when they capture a neutron. Some of the Li atoms (7Li and 6Li) absorb neutrons and make tritium.