San Onofre Nuclear Plant green power plant Needs To Replace Steam Generators

San Onofre nuclear power plant needs to have its aging steam generators replaced to keep the reactor running. Southern California Edison is seeking state approval to replace the generators and to spread the $680 million cost among ratepayers. The issue involves 22-year-old steam generators that were built to last 40 years but are showing their age way ahead of schedule. The generators inside San Onofre's two reactor domes are about 65 feet tall, up to 22 feet wide and 620 tons in weight apiece.

Each of San Onofre's reactor domes has two generators, and each generator has about 9,350 tubes that are cracking, forcing crews to plug them up for safety's sake. Under federal regulations, if 21.4 percent or more of the tubes are filled, the plant can be ordered to shut down. San Onofre's generators are about halfway toward that tube-plugging limit. There is a 25 percent probability that the generators in Unit 2 will reach the federal limit by 2010 and a 15 percent probability that those inside Unit 3 will do the same by 2017.

San Diego Gas & Electric, which has a 20 percent stake in San Onofre, has decided not to help pay for the improvements because the steam generator replacement project is too expensive and would cost its 1.2 million customers for $163 million to pay its share.

How Does Nuclear Energy Produce Electricity?

San Onofre Nuclear Generating Station

Southern California Edison, the plant's majority owner, placed an order in December 2004 with Japan's Mitsubishi Heavy Industries to manufacture the replacement generators for an undisclosed amount. If approved, the project at the San Onofre Nuclear Generating Station would be the largest capital project in the plant's history, outside construction of the reactors themselves. Unit 1 started generating power Jan. 1, 1968, and was shut down in 1992. Unit 2 went online in 1982 and Unit 3 in 1983.

It is similar to a project proposed for the Diablo Canyon nuclear power plant in San Luis Obispo County that earned a preliminary nod from a California Public Utilities Commission judge January. 25, 2005.

An administrative law judge for the PUC is holding hearings in San Francisco on the latest rate request. The PUC will make the final decision, probably in the spring of 2005. The rate case is important because San Onofre provides power to 2.2 million Southern Californians.

Iif the project does not win approval for the plant, it will be forced to shut down and the state would have to look for 2,200 megawatts of generation. Nuclear power plant opponents hope the rate increase request will be denied so that San Onofre would shut down when it is scheduled to close and its license expires in 2022. Plant officials would be hard-pressed to get the license renewed while still using the old steam generators. Installing new generators would lengthen the power plant's life beyond 2022.

Of the 104 licensed reactors in the United States, 69 are pressurized water reactors similar to San Onofre. Of those, 39 plants have already replaced their steam generators; the rest are still addressing the issue.

The city of Riverside is the only other plant co-owner to support the project. The city, which has a 1.8 percent ownership stake in the plant for its 101,700 customers, has agreed to contribute about $15 million.

Anaheim, which owns 3.1 percent of the plant, has opted out, choosing not to ask its 110,600 customers to pay an estimated $24 million toward the project.