Hungary's Paksi Atomeromu nuclear plant shut its second reactor today due to a cable fire that was quickly extinguished, it said in a statement.
It said the fire broke out this morning in the second reactor but was put out by an automatic fire extinguisher system.
"Such a cable fire has never happened in the Paks nuclear plant over the plant's 19 years of operation," the statement said.
"The reactor will be restarted after the faulty cables have been replaced and checks have been carried out, which will probably take several days."
It said the fire was preliminarily classified as zero grade on the seven-grade international nuclear event scale.
Paks has four reactors. It is Hungary's only nuclear plant, generating about 40 per cent of the country's electricity needs.