The crisis at Japan's Fukushima Daiichi nuclear power plants continues. Amazingly, a 40-year-old power plant built to withstand a 7.9 magnitude earthquake on the Richter scale shut down automatically as designed when the Earth began shaking. In fact, it stood up to an earthquake that released more than 40 times the amount of energy the plant was designed to survive. At the moment it appears that the 33-foot tsunami that knocked out its backup diesel generators for its coolant pumps was the plant'sundoing.
Two earlier explosions were hampering attempts to keep the reactor cores inundated with seawater, and a third explosion yesterday may have uncovered some of the spent fuel rods in a cooling pond at one of the facilities. The explosions appear to be caused by a buildup of highly volatile hydrogen gas within the facilities. After this latest explosion, radiation levels increased outside the facilities and residents within a 12-mile radius of the stricken plants have been evacuated and those living within 19 miles have been advised to stay indoors.
Reports are spotty, but exposure to radiation just outside the plant for one hour reached the equivalent of more than three years of naturally occurring radioactivity. Despite multiple setbacks, plant workers continue their heroic efforts to cool down the reactor cores. As I write, most experts believe that the plant woes will not produce major health or environmental consequences, although the clean up will cost Tokyo Electric billions.
Naturally, anti-nuclear activists and some policy makers around the world are citing the disaster as evidence that nuclear power is inherently unsafe and should be banned. For example, in Germany thousands of anti-nuclear protesters flooded the streets of Berlin shouting "turn them off." In response, German Chancellor Angela Merkel ordered that the country's seven nuclear power plants built before 1980 be shut down for a safety review. In the United States, Sen. Joe Lieberman (I-Conn.) and Rep. Edward Markey (D-Mass.) urged a moratorium on building new nuclear power plants.
Could it happen here? Although earthquakes can and do 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 and the San Onofre Nuclear Generating Station. The two reactors at the Diablo Canyon began operation in the mid-1980s and are built to withstand 7.5-magnitude earthquakes on the Richter scale. The reactors are located 85 feet above the coast. A recent analysis downgraded the most likely earthquake in the area to about half that.
The two reactors at San Onofre began operations in 1968 and are built to withstand a magnitude 7.0 earthquake. Seismic analysis indicates that the largest likely earthquake near that facility would register a 6.5 magnitude. The San Onofre reactors are enclosed by a 30-foot high tsunami wall. It should be noted that nearby Newport Beach experienced a 12-meter tsunami surge (39 feet) in 1934. The Sendai surge may have been about 33 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 the Sendai one. In January 1700 a magnitude 9.0 megathrust earthquake occurred sending tsunami waves across the Pacific to Japan and reached as much as eight meters above sea level (26 feet) 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, Energy in Transition, 1985-2010, in which one scenario suggested that the U.S. might be fueled by as many as 1,000 nuclear power plants by 2010. But the 1979 Three Mile Island accident boosted public opposition to nuclear energy. The good news was that 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, the Obama administration is insisting that it plans to go ahead with its policy of subsidizing new nuclear facilities with federal loan guarantees. Frankly, it is a real question if the 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 new and even safer nuclear power plants. Already, the Westinghouse division of Toshiba has developed and sold its passively safe AP1000 pressurized water reactor. The reactor is designed with safety systems that would cool down the reactor after an accident without the need for human intervention and operate using natural forces like gravity instead of relying on diesel generators and electric pumps. Until the recent events in Japan, the Nuclear Regulatory Commission was expected to give final approval to the design by this fall despite opposition by some anti-nuclear groups.
One innovative approach to using nuclear energy to produce electricity safely is to develop thorium reactors. Thorium is a naturally occurring radioactive element, which, unlike certain isotopes of uranium, cannot sustain a nuclear chain reaction. However, thorium can be doped with enough uranium or plutonium to sustain such a reaction. Liquid fluoride thorium reactors (LFTR) have a lot to recommend them with regard to safety. Fueled by a molten mixture of thorium and uranium dissolved in fluoride salts of lithium and beryllium at atmospheric pressure, 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, inherently 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.
It is estimated that 83 percent of LFTR waste products are safe within 10 years, while the remainder needs to be stored for 300 years. Another advantage is that LFTRs can use plutonium and nuclear waste as fuel, transmuting them into much less radioactive and harmful elements, thus eliminating the need for waste storage lasting up to 10,000 years. No commercial thorium reactors currently exist, although China announced a project earlier this year that aims to develop such reactors.
The main problem with energy supply systems is that for the last 100 years, governments have insisted on meddling with them, using subsidies, setting rates, and picking technologies. Consequently, entrepreneurs, consumers, and especially policymakers have no idea which power supply technologies actually provide the best balance between cost-effectiveness and safety. In any case, let's hope that the current nuclear disaster will not substantially add to the terrible woes the Japanese must bear as a result of nature's fickle cruelty.
Science Correspondent Ronald Bailey is author of Liberation Biology: The Scientific and Moral Case for the Biotech Revolution (Prometheus Books).