  Boundary conditions provide a simple and physically compelling Wilsonian
renormalization method in coordinate space in the framework of effective field
theory as applied to nucleon-nucleon interaction in the non perturbative
regime, enabling to remove unphysical regularization cut-offs while keeping
physical low energy threshold parameters such as the scattering length and
effective range invariant. We illustrate how the method successfully works in
the $^1S_0$ channel for the One Pion Exchange (OPE) and Two Pion Exchange (TPE)
potentials
