UPDATE 1-Tepco may restart nuclear reactor on Friday -Nikkei

TOKYO, May 6 (Reuters) - Tokyo Electric Power Co (Tepco) (9501.T) may begin a trial run of the No. 7 reactor at its quake-hit Kashiwazaki-Kariwa nuclear power plant, the world's biggest, as soon as Friday, the Nikkei business daily reported on Wednesday.

Restarting the No.7 reactor could reduce Tepco's annual fuel purchases by more than 70 billion yen ($710 million), cut carbon dioxide emissions by 5 million tonnes and save usage of 1.87 million kilolitres (32,000 barrels per day) of crude oil equivalent, according to company and Reuters calculations.

Tepco has already obtained approval from the local mayors of the city of Kashiwazaki and the village of Kariwa to restart the 1,356-megawatt No.7 reactor, but has yet to receive a final nod from the regional governor of Niigata, Hirohiko Izumida.

Izumida is now satisfied with Tepco's safety measures at the plant, and the prefectural assembly is likely to give the go-ahead for the trial run on Thursday, the Nikkei said.

All seven nuclear generators at the world's-biggest nuclear plant have been shut since a magnitude 6.8 quake hit the region in July 2007. The newest and least damaged No.7 unit would be the first of the seven to be restarted. ($1=98.70 Yen) (Reporting by Hugh Lawson and Osamu Tsukimori; Editing by Michael Urquhart)