SACRAMENTO -- At the dormant Rancho Seco nuclear power plant, it's possible to step through a truck-sized hole in the reactor building's 6-foot-thick concrete walls and stare into the chest of a former atom-smashing machine.
After 20 years and $500 million of demolition and cleaning at the site east of Galt, a visitor absorbs less radiation in this giant cylinder than during a cross-country flight. Yet the place emits a disquieting power, a reminder that energy choices have far-reaching consequences.
On June 6, 1989, Sacramento became the first -- and only -- community in the world to shutter a nuclear power plant by public vote. With no plan or budget to decommission the facility, the work dragged on for two decades.
The decision changed Sacramento's landscape. Among other things, it prompted Rancho Seco's owner, the Sacramento Municipal Utility District, to launch a massive energy conservation program that included planting a half-million trees.
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After the vote, SMUD had to diversify its energy supply, but it was able to stabilize rates and power delivery.
Environmentalists pressed hard for Rancho Seco's closure two decades ago. Today, some in the environmental movement and others are rethinking nuclear power.
But as public interest veers back toward nuclear power, Rancho Seco's legacy offers a powerful warning to choose carefully.
"People should be proud that the citizens did this," said Ed Smeloff, a SMUD board member at the time of the public vote, who now lives in Richmond and works in the solar power industry.
"I think it saved the utility, and it allowed people to be creative and pursue a much more sustainable course of activities," Smeloff said. "Nu-clear is very expensive. There is a legitimate argument that it is carbon-free technology, but it's not a pollution-free or cheap technology."
Critics tried to close Rancho Seco the first time in 1988, but SMUD won. It promised to improve Rancho Seco's performance and hold another vote in a year.
In the second ballot measure, which was advisory only, Rancho Seco's critics took 53 percent of the vote. SMUD began shutting down the reactor the next day.
To satisfy Sacramento's power needs, the district signed long-term contracts to buy power from other utilities, at less cost than the short-term purchases required during Rancho Seco's more than 100 unplanned times the reactor was down. As a result, rates and power supplies became more stable.
Within a few years, SMUD built a wind-energy project in Solano County and expanded its solar-panel arrays on the grounds of the reactor.
SMUD aggressively promoted energy-saving programs, including fluorescent bulbs and light-colored roofing, novel concepts at the time. It launched a complex industrial cleanup that has gone largely unnoticed.
In 2006, it built a 500-megawatt natural gas power plant on the Rancho Seco grounds.
The ominous twin cooling towers still dominate the reactor site, a permanent monument to the past. But cleanup work has transformed the rest of the property into a mostly benign catacomb of concrete and rusting steel.
There were scares along the way: a minor fire in the reactor building last year, and a worker who died of a heart attack in 2002. But given that few utilities have traveled this far down the nuclear decommissioning road, the process seems to have gone smoothly.
In 1991, cleanup costs were estimated at $281 million. The latest estimate is about $500 million.
Already, SMUD has demolished and hauled away 40 million pounds of steel, concrete, wiring and plumbing. Much of it went to a hazardous waste disposal site in Utah.
A formal closure order, expected from the Nuclear Regulatory Commission this year, will free most of the property for other uses. Two small waste storage areas will remain under NRC oversight.
Demolition posed numerous challenges, notably the need to protect workers and the public from radiation.
The reactor vessel -- with its 17-inch-thick steel walls -- was too large to fit on a rail car. It had to be cut up, a process that required robotic cutting equipment to avoid exposing workers to radiation.
"I can tell you, they don't build these things to take them down," said Einar Ronningen, Rancho Seco superintendent.
The plant was closed during an era of enormous concern about nuclear safety. The vote came just three years after the Soviet Union's Chernobyl reactor exploded and a decade after the partial meltdown of the Three Mile Island reactor in Pennsylvania.
Rancho Seco's history was filled with safety and reliability problems.
The worst was a 1985 "overcooling" event in which operators lost control of the plant and it shut down automatically. It remained offline more than two years while SMUD spent more than $300 million on safety upgrades.
"There were days it felt like it was us against the world, and it put a lot of strain on SMUD as an organization financially," said Jim Shetler, the utility's assistant general manager, who was part of the Rancho Seco management team before the vote.
SMUD paid $745,000 in federal fines for violations at Rancho Seco through 1989.
The plant had a lifetime operating efficiency rating of 38 percent, according to the Nuclear Energy Institute, compared with the 1990 industry average of 66 percent.
"Our industry was not operating our plants at the level that they should have been to boost public confidence," said Steve Kerekes, spokesman for the institute.
Today, a growing desire for alternatives to fossil fuel coincides with improved efficiency at the nation's 104 nuclear power plants -- 91 percent last year -- largely because of improved training.
A Gallup poll in March found that 59 percent of U.S. residents favor the use of nuclear power, the highest approval in the 15 years the survey has asked that question.
Nuclear power produces abundant energy with zero carbon emissions, factors that position it as an easy answer to the dual challenge of rising energy demand and climate change.
"There's no quantitative way to get this right without the nuclear industry playing a really large role," economist Jeffrey Sachs, director of Columbia University's Earth Institute, said in a speech last week. "It's not a happy thought, but it's unavoidable."
History shows: Other options
Rancho Seco, however, showed that relying on one technology is a risky gambit, according to Ralph Cavanagh, co-director of the energy program at the Natural Resources Defense Council. That Sacramento could shutter its biggest energy source overnight and continue growing on a mix of conservation and renewable power suggests there are other options, he said.
Building nuclear generation remains far more expensive than any other power source. A study this year by the Massachusetts Institute of Technology found that a nuclear power plant is twice as expensive to construct as a coal plant and four times the cost of a natural gas plant.
If coal and natural gas are taxed for their carbon emissions, however, nuclear can be competitive.
Seventeen license applications for 26 new reactors are pending at the NRC. It remains to be seen whether ratepayers and investors are willing to front the costs.
Waste disposal remains a great worry. Just as coal and natural gas have a carbon disposal problem, nuclear has a radioactive waste disposal problem -- and both remain unsolved.
Ten acres at Rancho Seco are committed indefinitely to this problem.
Behind a razor-wire fence, earthen and concrete barriers, a 24-hour guard, radiation sensors and cameras scanning every square inch are Rancho Seco's 22 above-ground fuel storage casks.
Within each concrete vault is a stainless steel and lead cylinder about the size of a minivan. A toxic legacy is welded inside the cylinders: 493 spent fuel assemblies, each filled with thousands of deadly radioactive pellets.
One cylinder holds the most radioactive of the demolished reactor components.
Stand about 100 yards from the casks and you'll soak up less radiation than exists at natural background levels in surrounding grasslands, says Ronningen. Get up close and you had better not stay long.
A building nearby holds debris that might be called "medium-hot." It's too toxic for conventional landfills but not hot enough to become a federal problem.
No suitable disposal facility exists for any of the material, so SMUD spends $6 million a year to ensure that it doesn't poison the public or fall into criminal hands, Ronningen said. Ratepayers are stuck with the bill -- unless the federal government fulfills its legal obligation to provide a permanent storage site.
Congress decreed in 1987 that Nevada's Yucca Mountain would be that place. However, terrorism fears made this single-site strategy seem foolish, and President Barack Obama has declared that Yucca Mountain no longer will be considered as a disposal site.
Obama believes nuclear power has a role in the nation's future. "We must harness the power of nuclear energy on behalf of our efforts to combat climate change," he said in April.
But in California a 1976 law forbids new nuclear energy plants until the federal government opens a permanent waste storage facility. Partly for this reason, nuclear is not one of the "renewable" sources that California utilities may use to satisfy greenhouse-gas reduction mandates.