The evolution of the reactor-antineutrino spectrum toward equilibrium above
the inverse-beta-decay threshold during the reactor operating period and t
he decay of residual D, radiation after reactor shutdown are considered. It
is Found that,, under certain conditions, these processes can play a signi
ficant role in experiments seeking neutrino oscillations. (C) 2001 MAIK "Na
uka/Interperiodica".