Japan continues to deal with an incredible tragedy right now. The earthquake on March 11 triggered a tsunami that hit the country's east coast, killing thousands and decimating the landscape. We mourn the losses and pray for the survivors and relief workers.
In the U.S., our attention has now shifted toward the nuclear power generation plants at Fukushima Daiichi, heavily damaged by the quake and tsunami, as operators work tirelessly to fend off nuclear disaster.
The struggles at Fukushima have brought many companies into the spotlight, including reactor designer General Electric
To get the scoop, I interviewed my father, Butch Meier, who's had decades of experience working with nuclear energy. The views he will express are his own, but based on his experience, he's got plenty of interesting things to say. We'll learn more about the situation at Fukushima, what the workers are trying to prevent, and how you can help. So let's get right to it.
David Meier: I may know about your background, but readers don't. What's your experience with nuclear energy?
Butch Meier: I studied reactor theory and design at the United States Naval Academy and in graduate school on an Atomic Energy Commission Fellowship at the University of Arizona. I served in U.S. Navy nuclear submarines for 29 years. Since 1998, I have done consulting work in related fields.
David: Why is cooling water so important for the situation at Fukushima right now?
Butch: Keeping things cool is vital.
Here's the problem the Japanese are trying to overcome: The earthquake, followed by the tsunami, absolutely wiped out their infrastructure, causing the cooling pumps to lose power. They have also experienced fires in the pumps providing cooling water to the spent fuel pools. Without a flow of cooling water, the water in the core or spent fuel pool eventually boils. With no water to remove the decay heat, the temperature of the fuel rises, causing the pressure to increase. In the limit, it can increase to the point that the fuel cell ruptures, which would release radioactive fission products. Chernobyl is the only example where this has happened.
(Editor's note: Tokyo Electric Power is working hard to restore dedicated power to the reactors in order to get the cooling systems working.)
David: Are the reactors running right now?
Butch: No. The reactors are shut down, and there is no worry about them restarting. The issue centers on the fission products in the shutdown reactors -- atoms that are produced when uranium atoms split in the fission process.
David: Speaking of uranium, the fuel used in a nuclear reactor, what goes on inside to create heat and radioactive byproducts?
Butch: When a uranium atom fissions, or splits, it releases energy as it splits into two other midweight atoms. ... These unstable radioactive atoms decay as they seek a stable state, emitting radiation in the process. Fissions still occur when the reactors are shut down -- just not at the rate when the reactor is "critical" or producing power. The shutdown fission rate is 8-10 or more orders of magnitude lower than during reactor operation.
Two types of radiation -- gamma rays (think of X-rays) and neutrons -- emitted from these decay products generate heat by mechanical interaction. Some of the neutrons are absorbed in the uranium fuel, causing more fission and more heat. So while the shutdown reactor doesn't require anywhere near the cooling needed when it is operating, it still requires cooling. Even the spent fuel removed from the reactors still generates heat. Water is the most prevalent coolant.
You may have heard that boric acid or borated water is being pumped into the cores. (Editor's note: South Korea has agreed to send some of its boron reserve to Japan.) Boron has a tremendous affinity for neutrons. It prefers to absorb them rather than the fuel, reducing the heat generated.
David: There have been reports of explosions at the plant. How do you think those happened?
Butch: Steam pressure from boiling water in the uncooled core has to be vented, or it could rupture the core vessel and the containment around the core vessel. (Editor's note: For a reactor diagram, see "Inside the Reactors" here.) Hydrogen is also produced in the core. The gas is vented into the containment building around the two inner containments. The vented gas also contains some radioactivity. The explosions that have occurred involve this hydrogen-steam mixture buildup, coupled with the loss of power and the ability to ventilate the containment building.
David: News headlines flash that radiation levels are high or rising. That doesn't tell the whole story. Break down the types of radiation -- how it can interact with humans or the environment, and how can people protect themselves against radiation?
Butch: Radiation is a challenging subject to discuss meaningfully. You can't see it, feel it, or taste it. We are not familiar with units, which are millisieverts, unlike a gallon of milk or the yards on a football field. But the effects of the various types of radiation and doses/dose rates -- the intensity and accumulation of radiation -- are well understood and documented. (Editor's note: This CNN blog entry does a nice job of putting things in perspective.)
There are four types of radiation. Gamma and neutron radiation, discussed above, can penetrate the body and cause long-term health problems under chronic exposure. Exposure to extremely concentrated doses could be immediately fatal. From what I have read, Fukushima is nowhere near exposures that are harmful.
Two others -- alpha and beta -- don't penetrate, and are only a problem if you ingest them or absorb them. You mitigate the gamma and neutron radiation by time, distance, and shielding. You mitigate alpha and beta radiation by staying inside or using filters or masks. The contaminations you see and hear about on TV are predominantly alpha and beta. (Editor's note: Japanese officials have been ordering people to stay inside and pictures show relief working with masks covering their noses and mouths.)
The release of the fission products in the cores and spent fuel pose the radiation hazard due to large amounts of long-lived penetrating radioactivity. Two fission product isotopes, cesium and strontium, are readily taken up by the body (bones, marrow), plants, food supply, etc. While they are not the most abundant fission products, they are long-lived and are a significant hazard.
Another fission product of concern is iodine, which concentrates in the thyroid. The potassium iodide tablets the government passed out are designed to flood the thyroid so it can't take up any more, thus blocking any released radioactive iodine. Note that the government has just made the tablets available – they haven't told the people to take them, because they do not presently anticipate fission products released. If they do direct the people to take them, the problem is getting worse.
David: Let's go back to the beginning. On March 11, there was an earthquake measuring 8.9 on the Richter scale off the northeast coast of Japan. This caused a tsunami to hit the east coast, causing massive damage to homes, land, and infrastructure, including loss of power, reduced communication, and damage to the Fukushima nuclear plant. How well are Japanese officials and workers handling the situation?
Butch: Some perspective will help. The 1906 San Francisco earthquake is estimated as an 8 on the Richter scale -- it flattened the city. The 8.9 quake is one of the three or four most powerful ever. For perspective, the energy released in the Japan earthquake is about 30 times that released in San Francisco. Japanese officials have an almost impossible task, but they are doing well in my opinion.
David: The troubles at Fukushima conjure images of Three Mile Island for many, Chernobyl for others, and perhaps even Hiroshima and Nagasaki for some. Should operators lose control of the recovery effort in the plant, what would you be most worried about?
Butch: The release of the fission products in the cores and spent fuel -- no question.
David: We shouldn't take the possibility of a nuclear disaster lightly -- and no one is. What do you think is missing from the disaster in Japan?
Butch: Essentially the same thing that was missing in the Three Mile Island accident -- useful practical public education of the basics of nuclear power, including the risks, and media reporting that uses the context of technical facts. Our news media is quite driven by hysteria and sensationalism rather than facts and information -- that is not useful.
How you can help
The tragedy in Japan gives us a great opportunity to learn. I hope that you leave this interview with more knowledge about the challenges at Fukushima.
There's also a chance to improve the lives of the survivors over in Japan by donating to the relief efforts. Please consider making a contribution. The story of the struggle at Fukushima has pushed the needs of the tsunami victims off of the front page, but you can read "Donating to Japan" to learn more about how to make a contribution.