An enlarged electroweak symmetry group SUL(2) x U-Y(1) x U'(1) is broken to
U-em(1) at sigma = 246 GeV due to radiative corrections. The resulting Col
eman-Weinberg potential explains the inflation at 246 GeV scale successfull
y and the mass of the additional weakly coupled gauge boson Z' has a value
close to 252 GeV accessible to present-day high energy accelerators.