Global power generated by nuclear reactors fell about 3.6% in calendar 2007 from the 2.8 billion megawatt-hours (MWh) recorded in 2006, according to data released by Nucleonics Week, a publication of Platts, a leading global provider of energy and cGlobal power generated by nuclear reactors fell about 3.6% in calendar 2007 from the 2.8 billion megawatt-hours (MWh) recorded in 2006ommodities information.

In the otherwise lackluster 2007, US reactors set a record for nuclear power generation, with output surging to 843 million gross MWh and utilizing an average 91% of reactor capacity. "The 2007 nuclear plant performance means about 20% of US electricity was once again generated without the carbon emissions that would otherwise contribute to global warming," said Margaret Ryan, Platts global nuclear editorial director.

World performance was led by two US reactors. In terms of output, South Texas Project's South Texas-1 in Bay City, Texas, generated 12.36 million MWh, the largest output of any reactor in the world. Of the 15 reactors generating the most in 2007, three were from the US, eight from Germany and four from France. In terms of capacity factor, which measures how well a plant performed against the output level its manufacturer promised, the best worldwide was Constellation Energy's Calvert Cliffs-1, south of Annapolis, Maryland, which actually exceeded its rated capacity level all year. Of the top 15 best performing reactors in 2007 measured by capacity, 11 were from the US and four were from Japan.

The slowdown in world nuclear power generation was in large part attributable to developments ranging from an earthquake in Japan to persistent aging of facilities in the UK to unplanned outages in Germany. Elsewhere, nuclear generation sustained good performance or went up or down by smaller amounts.

In terms of world nuclear power plant generating capacity, the median utilization rate was 84.2% with the top quarter of units all performing above 91.5%. This suggests many reactors performed very well during 2007. But with a total nominal operating capacity of 395 gross gigawatts, the 439 nuclear units worldwide could, if they had operated at an average 85% capacity factor, have generated some 400 million more MWh to meet growing world electricity demand than they did in 2007. That amount would supply the entire United States, which uses more electricity than any other country in the world, for 40 average days.

Outlook

The year 2007 began inauspiciously for nuclear power, with the closure of seven units on the last day of 2006. The shutdowns of Bulgaria's Kozloduy-3 and -4, Slovakia's Bohunice-1, and the UK's Dungeness A-1 and -2 and Sizewell A-1 and -2 removed 2,540 gross MW from the electricity grid.

Only four reactor units were added to world's operating nuclear fleets in 2007: India's Nuclear Power Corporation brought the 220-MW Kaiga-3 into service, the 1,000-MW Tianwan-2 VVER was started up in China, and Romania commissioned the 706-MW Cernavoda-2 Candu unit. In the US, the Tennessee Valley Authority brought the 1,155-MW Browns Ferry-1 back into service after 22 years of shutdown. That brought the total MW added to just less than 3,100 MW.

But 2007 brought the most construction starts of nuclear power reactors in recent years, with work on five units officially launched. Construction of the 650-MW Qinshan II-4 and the 1,000-MW Hongyanhe-1 in China, the 1,000-MW Shin Kori-2 and Shin Wolsong-1 in South Korea, and the 1,650-MW Flamanville-3 in France all got under way. In 2006 there were construction starts on four units, three in 2005 and just two in 2004, according to International Atomic Energy Agency records.