The U.S. has lost three percent of its summertime nuclear generating capacity as troublesome plants are retired.

Robert Stone’s controversial film Pandora’s Promise has brought the question of how nuclear power might fit into a clean-energy future to center stage. We’re not going to hold (let alone resolve) that debate here and now. Instead, we’ll just note that in what looks like it could be a long, hot summer, Americans will have to keep their air-conditioning going with less nuclear power.

This is the word from the Energy Information Administration, which says four nuclear units have recently been retired, reducing the number of operating nuclear reactors in the U.S. to 100, and dropping net summer capacity by 3 percent.

None of these plants made it to age 40, once seen as the expected working life for a nuke. So what’s driving the early retirements? “Decisions to retire the units involved concerns over maintenance and repair costs and declining profitability,” the EIA said.

Most of the lost capacity is happening at one site, the San Onofre Nuclear Generating Station (aka, SONGS). This is a nuke with a view that a luxury hotel would love: It’s right on the Pacific Ocean midway between LA and San Diego. In 2011, the two units at San Onofre produced about a fifth of Southern California Edison’s electricity. But even though new steam generators were installed in 2009 and 2010, evidence of a leak in January 2012 shut the plant down. And it couldn’t get up.

Also going into mothballs (if it were only so easy with nukes): The 556-MW Kewaunee Power Station in Wisconsin, due to “lower wholesale power prices” as its long-term power purchase agreements expired; and the 860-MW Crystal River Unit 3 in Florida. As with San Onofre, plant owners in Florida decided that repairing its problems would be too costly and too much trouble.

All told, that’s 3,466 megawatts of generating capacity gone by the wayside. That makes the new nuclear generating capacity expected in the next five years – 5,600 megawatts – seem not so much a boon but pretty modest, marginal growth. (Good thing a whole lot more solar is coming: annual additions are expected to reach 9,200 megawatts in 2016.)

Here’s what’s in the nuke pipeline, according to the EIA:

The completion of construction at the Tennessee Valley Authority’s Watts Bar 2 in 2015 is expected to add almost 1,200 megawatts of new nuclear capacity. During 2012, the NRC issued combined operating licenses for four new nuclear reactors at two plants: Vogtle, units 3 and 4 in Georgia, and Virgil C. Summer, units 2 and 3 in South Carolina. The four reactors have a total capacity of almost 4,500 megawatts and are now under construction, with target dates for completion between 2016 and 2018. There are also plans for capacity uprates at existing reactors. These plans include approximately 1,000 MW of uprate capacity currently under review by the NRC. However, Exelon Nuclear, which operates 17 reactors, recently announced that uprates previously approved by NRC, at LaSalle units 1 and 2 as well as Limerick units 1 and 2, will be delayed.

Pete Danko, July 3, 2013 via Earth Techling