Be corrosion in magnesium phosphate cements

At SCK CEN, the evaluation of the corrosion rate and mechanism of beryllium was studied by using S-200-F Be grade, corresponding to the grade used in the matrix of the Belgian Reactor 2 (BR2). Part of the samples were cut into pellets to allow the corrosion tests. The first tests were started in solution representative for the OPC pore solution. The first results obtained from the hydrogen concentration measurement gave a corrosion rate evolving around 5 to 10 μm/y. This needs to be compared to the electrochemical tests. New tests will start in direct contact with OPC cement paste to study the effect of the matrix. Tests in solutions representative for MPC or in MPC pastes will also be started afterwards. At FZJ, the Be corrosion was studied by gravimetry in alkaline solutions (pH 12.2 and 13.95), representative of OPC pore fluids (Figure 18). At pH 12.2, the corrosion rate is lower than 5 μm/y, which is close to or below the detection limit. At pH 13.95, the corrosion is active. The initial corrosion rate is around 195 μm/y and tends to a steady state around 135.2 μm/y after 7 d. The Be surface was characterized by SEM after immersion in the alkaline solutions (Figure 19). After 7 d of immersion at pH 12.2, the stripes initially present on the Be surface are still observed and a few small corrosion pits appeared. After 10 d of immersion at pH 13.95, the stripes are less visible and more pits are observed and their surfaces are bigger than at pH 12.2.