Gas production in the SFR repository and its possible consequences for contaminant release

Iron in the silo may corrode by reacting with water, forming hydrogen gas. The hydrogen pressure will increase with time and expel out potentially contaminated water. The internal pressure in the silo may grow to more than 0.5 to 1.0 MPa. At this pressure, the concrete walls of the silo will crack, forming fissures through which the gas and water may flow faster. To avoid this faster outflow of water, it is proposed that the top of the silo should be constructed with venting channels, which allow the gas to escape at a lower internal overpressure. This will considerably reduce the pressure in the silo and the outflow of contaminants from the silo will be less. By further surrounding the concrete boxes containing the waste with a low-capillarity, high-permeability concrete, less water will be exchanged with the interior of the boxes. A central case was defined where the parameter values were chosen such that they would represent a reasonably conservative case. Calculations were made for various combinations of values of the parameters