TOKYO A power failure and smoke release occurred at Nippon Steel & Sumitomo Metal Corp's Nagoya steel plant in central Japan on Monday, just three days after the facility was hit with similar problems.
At 9:10 local time (0010 GMT) a power failure occurred and smoke started to billow from a coke oven, a company spokesman said, adding the smoke stopped about two hours later.
The entire plant had been shutdown on Friday when flames and smoke escaped from a coke oven after an electricity outage. The company said the smoke and flames came from a process to burn off gas accumulated during operations and not from a fire.
Nippon Steel began gradually restarting units at the facility on Saturday after power supply returned, the company spokesman said.
The steelmaker is trying to determine the cause and exact location of Monday's power shortage and smoke release, as well as how much of the plant was still operating, the company spokesman said.
There is no estimate for when plant, which produced 6.46 million tonnes of crude steel in the year to March 2013, will return to production, he added.
However, after Friday's incident, Nippon Steel assured Toyota Motor Corp and other automakers that it would have minimal affect on supply, the Nikkei business daily reported on Saturday.
Shares in Nippon Steel were up 0.6 percent at the midday break, versus an 0.6 percent decline in the Nikkei stock benchmark.
(Reporting by James Topham)