Assessment of THM coupling in the near field of the potential HLW repository by semi-analytic approach

Many fundamental R and D's on the effect of the THM coupling on the structural stability as well as the long term post-closure radiological safety are performed world-wide. In this paper, the impact of coupling among decay heat in spent fuel, stress redistribution in the bentonite buffer layer as well as the adjacent rock, and change in the groundwater velocities in the near fields is analyzed using the semi-analytic approach. The linear thermo-elastic constitutive equation is solved with proper boundary and initial conditions in the vicinity of the potential repository. The final solution, semi-analytic one, is calculated by the Talbot's numerical Laplace transform method. Numerical illustrations with input data describing physical properties of bentonite and granite show that the values of groundwater velocities in the rock as well as bentonite are so low that the advective transport of the radionuclides, potentially released into the buffer from the canisters, can be neglected in the total system performance assessment under the conditions given in this mathematical model