As I write this, cleanup workers had entered one of the Fukushima nuclear reactor buildings for the first time since explosions rocked the plant, the day after it was inundated by a tsunami generated by a devastating 9.0 magnitude earthquake on March 11. In early April, the Japanese government elevated the disaster to Level 7 on the International Nuclear and Radiological Event Scale. That is the highest level on the scale, putting it on a par with the 1986 Chernobyl reactor explosion.
The good news is that the Fukushima reactors emitted only about a tenth as much radioactive material as Chernobyl, most of which floated out over uninhabited ocean where it was diluted to background levels in seawater. The plant's owner, Tokyo Electric Power, now expects to have the reactors and spent-fuel pools cool and stable in nine months, just shy of a year after the tsunami knocked them out. The cleanup will cost billions of dollars, and the company may end up being nationalized. The U.S. Environmental Protection Agency reports that while its monitors have detected traces of radionuclides (unstable atoms that undergo radioactive decay) from Fukushima in America, all of the radiation levels detected "are hundreds of times below levels of concern."
Naturally, many activists and policy makers cited the disaster as evidence that nuclear power is inherently unsafe and should be banned. In Germany, for example, thousands of anti-nuclear protesters flooded the streets of Berlin in March shouting, "Turn them off!" In April, German Chancellor Angela Merkel announced, "We want to exit from nuclear power generation as soon as possible and make the transition to renewable energy sources faster." In the United States, Sen. Joe Lieberman (I-Conn.) and Rep. Edward Markey (D-Mass.) urged a moratorium on building new nuclear plants.
Could a Fukushima-level disaster happen here? Although earthquakes can occur all over the United States, the West Coast and Alaska are the most seismically active regions. The facilities whose physical locations most closely resemble that of the Fukushima plants are two nuclear generating plants built on the coast of California, the Diablo Canyon Power Plant near San Luis Obispo and the San Onofre Nuclear Generating Station near San Diego. The two reactors at the Diablo Canyon, which are located 85 feet above the coast, began operation in the mid-1980s and are built to withstand a 7.5-magnitude earthquake. A January 2011 analysis presented to the Nuclear Regulatory Commission by Pacific Gas & Electric geologists downgraded the most likely earthquake in the area to about half that size.
The two reactors at San Onofre, which began operating in 1968, are built to withstand a 7.0-magnitude earthquake. Seismic analysis indicates that the largest likely earthquake near that facility would register a magnitude of 6.5. The San Onofre reactors are enclosed by a 30-foot-high tsunami wall. It should be noted that nearby Newport Beach experienced a 39-foot tsunami surge in 1934. The Sendai surge in Japan may have reached 46 feet in height.
The Cascadia subduction zone off the coast of Washington, Oregon, and Northern California is the region most likely to experience an earthquake equivalent to one that hit eastern Japan in March. In January 1700, a 9.0-magnitude megathrust earthquake occurred there, sending tsunami waves that crossed the Pacific to Japan and reached as much as 26 feet above sea level onshore in the Pacific Northwest. Fortunately, the closest nuclear power plant, the Columbia Generating Station, is located 200 miles inland.
Back in 1980, during the "energy crisis," the National Research Council issued a report called Energy in Transition, 1985–2010. One of its scenarios suggested that the U.S. might be fueled by as many as 1,000 nuclear power plants by 2010. But the previous year's Three Mile Island accident boosted public opposition to nuclear energy. That partial reactor meltdown had essentially no health consequences other than anxiety. Nevertheless, no new reactors were ordered in the United States until recently. Despite the Japanese situation and new polls showing that 50 percent of Americans disapprove of building new nuclear plants, the Obama administration is insisting that it plans to proceed with a policy of subsidizing new nuclear facilities with federal loan guarantees. It is unclear whether private utilities would choose to build the current versions of nuclear plants without federal loan guarantees and the backstop of federal disaster insurance.
One hopeful possibility is that the Japanese crisis will spark the development and deployment of newer, safer nuclear plants. Already the Westinghouse division of Toshiba has developed and sold its passively safe AP1000 pressurized water reactor. The facility is designed with safety systems that would cool down the reactor after an accident without the need for human intervention, drawing on natural forces such as gravity instead of relying on diesel generators and electric pumps. The Nuclear Regulatory Commission was expected to give final approval to the Westinghouse design this September. A number of environmental groups have now petitioned the commission to delay its decision.
One innovative approach to safer nuclear energy is the use of thorium reactors. Thorium is a naturally occurring radioactive element that, unlike certain isotopes of uranium, cannot sustain a nuclear chain reaction. It can, however, be doped with enough uranium or plutonium to sustain such a reaction. Fueled by a molten mixture of thorium and uranium dissolved in fluoride salts of lithium and beryllium at atmospheric pressure, liquid fluoride thorium reactors (LFTRs) cannot melt down. (Strictly speaking, the fuel is already melted.)
Because LFTRs operate at atmospheric pressure, they are less likely than conventional pressurized reactors to spew radioactive elements if an accident occurs. In addition, an increase in operating temperature slows down the nuclear chain reaction, stabilizing the reactor. And LFTRs are designed with a salt plug at the bottom that melts if reactor temperatures somehow do rise too high, draining reactor fluid into a containment vessel where it essentially freezes.
A 2009 NASA report notes that the radioactivity in wastes from LFTRs "would decay to background levels in less than 300 years, as contrasted to over 10,000 years for currently used reactors, thus obviating the need for long term storage, such as at Yucca Mountain." In fact, LFTRs can burn the long-lived plutonium and other nuclear wastes produced by conventional reactors as fuel, transmuting them into much less radioactive and harmful elements. No commercial thorium reactors currently exist, although China announced a project earlier this year aimed at developing some.
The main problem with energy supply systems is that for the last 100 years governments have insisted on meddling with them, deploying subsidies, setting rates, and picking technological winners. Consequently, entrepreneurs, consumers, and especially policy makers have no idea which power supply technologies actually provide the best balance between cost-effectiveness and safety. Thorium reactors might provide the right balance among considerations of cost, safety, and environmental impact. But the political economy of energy is so vexed by activists, corporate lobbyists, and politicians that it's hard to tell.