Equilibrium and Transport Properties of Aqueous Triborate up to PWR Coolant Conditions by Flow AC Conductivity

Abstract

Thermodynamic data for boric acid, borates and polyborates are needed to model the chemistry in fuel deposit crevices of pressurized water reactors under 'hideout' conditions that lead to crud-induced power shifts (CIPS), and for bulk PWR high temperature coolant chemistry. This paper reports final results of a study aimed at measuring accurate triborate formation constants from 10 to 200 °C, using a unique high-precision flow-through AC conductance instrument. Together with our experimental ionization constant of boric acid reported last year, the results have been used to extend the database of the EPRI chemical modelling program MULTEQ to PWR primary coolant 'hideout' conditions.