  We discuss a class of stochastic second-order PDEs in one space-dimension
with an inner boundary moving according to a possibly non-linear, Stefan-type
condition. We show that proper separation of phases is attained, i.e., the
solution remains negative on one side and positive on the other side of the
moving interface, when started with the appropriate initial conditions. To
extend results from deterministic settings to the stochastic case, we establish
a Wong-Zakai type approximation. After a coordinate transformation the problems
are reformulated and analysed in terms of stochastic evolution equations on
domains of fractional powers of linear operators.
