Soviet newspapers have reported that at least six senior plant officials, including the director, were dismissed after the accident.
No one was injured, plant officials said today in a prepared statement.
But plant officials here said they were not simply copying Japanese techniques.
Something, possibly water, reacted with the sodium to cause the explosion, plant officials said.
State, Federal and plant officials said there was no danger to the public.
Three other former Soviet plant officials received shorter terms in a labor camp.
But plant officials were not immediately available to confirm the report.
The 650-megawatt plant continued to operate at full power, plant officials said.
He said plant officials would cooperate fully with the commission's inquiry.
Five went home with it on their shoes, plant officials said.