By Scott DiSavino
July 31 (Reuters) - Planned refueling outages at U.S. nuclear power plants this autumn are expected to drop to the lowest level in years due in part to the retirement of four reactors in 2013, according to data from a Reuters survey released Wednesday.
About 14,300 megawatts (MW) of nuclear capacity, more than half of the outage level seen last year, is expected to be offline at the peak of the 2013 autumn refueling season, which typically occurs in mid-October, the survey showed.
In 2012, autumn refueling outages topped out near 32,000 MW, the highest level seen since at least the late 1990s, according to the data.
Natural gas traders follow nuclear outages closely because plants burning gas typically make up much of the power supply when the nuclear plants shut.
Last year, hefty nuclear outages helped shift more demand to gas and underpin price gains at a time when use of the fuel usually slows with milder autumn temperatures.
It takes roughly 200 million cubic feet of natural gas per day to generate about 1,000 MW. One megawatt can power about 800 homes.
In 2013, U.S. generating companies have retired four reactors, the most in any year, due to weak power market conditions or because the plants were too costly to repair.
The four retired reactors, which have a total capacity of 3,576 MW, are Dominion Resources Inc’s Kewaunee in Wisconsin, Duke Energy Corp’s Crystal River 3 in Florida and Edison International’s San Onofre 2 and 3 in California.
For a factbox on U.S. nuclear power reactors that have been shut
The survey assumes Omaha Public Power District’s 478-MW Fort Calhoun plant in Nebraska will still be shut in mid October.
Fort Calhoun shut for refueling in April 2011 and has remained down due to damage caused by flooding of the Missouri River and needed safety upgrades since.
The data also assumes that in addition to the 12,300 MW of nuclear capacity expected to be out for refueling and maintenance on Oct. 15 - the date of the usual autumn peak - there will be about 2,000 MW of other capacity off for unexpected reasons.
The 2,000 MW is the average amount of nuclear generation shut for unexpected, usually short-term reasons over the past five years.
Since 1999, autumn outages peaked near 32,000 MW in October 2012 and bottomed at about 12,300 MW in 2004. Spring outages have peaked near 32,800 MW in May 2011 and bottomed at 16,100 MW in 2004.
Nuclear outages over the last five years have averaged about 24,100 MW in spring (2009-13) and 21,500 MW in the autumn (2008-12).
There are now 100 operating nuclear reactors in the United States capable of generating over 97,800 MW, enough to power about 80 million homes.
Nuclear reactors produce about 20 percent of the country’s generation and operate around the clock as baseload facilities, providing some of the lowest-cost power.