  We perform a systematic analysis of the one-loop effective potential of pure
$d=5$ supergravities, with supersymmetry fully broken by a Scherk-Schwarz
compactification on the circle, as a function of the radial modulus. We discuss
the precise correspondence between the effective potential $V_1$ in the full
compactified theory and its counterpart $V_{1,red}$ in the reduced theory. We
confirm that $V_1$ is finite for any $N>0$, in contrast to $V_{1,red}$. We find
that for broken $N=8$ supergravity $V_1$ is negative definite even after
accounting for the Kaluza-Klein states. We outline a program for future work
where the study of a different kind of Scherk-Schwarz compactifications, still
at the field theory level but with at least three extra dimensions, could lead
to qualitatively new results.
