DIFFUSION ACROSS BARRIERS: TWO IMPORTANT PARAMETERS

Two parameters characterize the exceptional retention capability of SSiC for radioactive fission products:

• the breakthrough time
• the diffusion rate

The breakthrough time describes the phase of diffusion through the barrier wall before equilibrium has been reached. It characterizes the maximal retention time for source term ZERO.

Later, the source term Q becomes proportional to the diffusion rate.

Obviously, thick walls give long break through times and low leakage rates.

The question is: How thick is thick enough?