  Being a superluminous supernova (SLSN), PTF12dam can be explained by a
$^{56}$Ni-powered model, a magnetar-powered model or an interaction model. We
propose that PTF12dam is a pulsational pair instability supernova, where the
outer envelope of a progenitor is ejected during the pulsations. Thus, it is
powered by double energy source: radioactive decay of $^{56}$Ni and a radiative
shock in a dense circumstellar medium. To describe multicolor light curves and
spectra we use radiation hydrodynamics calculations of STELLA code. We found
that light curves are well described in the model with 40M$_{\odot}$ ejecta and
20-40M$_{\odot}$ circumstellar medium. The ejected $^{56}$Ni mass is about
6M$_{\odot}$ which results from explosive nucleosynthesis with large explosion
energy (2-3)$\cdot$10$^{52}$ ergs. In comparison with alternative scenarios of
pair-instability supernova and magnetar-powered supernova, in interaction model
all the observed main photometric characteristics are well reproduced:
multicolor light curves, color temperatures, and photospheric velocities.
