TOKYO - The nuclear power plant utilization rate at Japan's 10 nuclear power companies rose to its highest in more than three years in December as many companies boosted output for peak winter demand, helping cut the need for thermal fuel.

The average run rate rose to 74.0 percent in December, from 62.5 percent in December 2008, the Ministry of Economy, Trade and Industry (METI) said on Friday.

That was the highest since 75.9 percent in August 2006 and compared with 66.6 percent in November.

The average run rate for calendar 2009 was 64.7 percent, up from a five-year low of 58.0 percent in 2008,

But that was still much lower than 70.2 percent in 2006, before the rate dropped due to earthquake-related shutdowns at plants including Tokyo Electric's Kashiwazaki-Kariwa plant in 2007 and Chubu Electric's Hamaoka plant in August last year, a METI official said.

In late December, Hokkaido Electric Power Co started commercial operations at the 912-megawatt Tomari No.3 reactor, the first new operations in Japan since Hokuriku Electric Power's Shika No.2 reactor in March 2006.

With the start of the new Tomari unit, Japan now has 54 reactors for commercial use, for a total generating capacity of 48,847 megawatts, the world's third-biggest nuclear generation capacity after the United States and France.