Let $k$ be a field, $R$ a $k$-algebra (of finite type if necessary!), $B$ an algebra of finite type over ring of formal Laurant series $R((t))$, which is smooth.

up to this generality, can one construct a flat model of $B$ over ring of formal power series $R[[t]]$ (i.e. a flat algebra $\tilde{B}$ over $R[[t]]$ such that $\tilde{B}\otimes_{R[[t]]}R((t))=B$)? if not what could be the weakest assumption that will serve it?