In the past two weeks, I have blogged a couple of times about the nuclear reactor problems in Fukushima Prefecture, Japan, and have expressed concern about the radiation levels outside the evacuation zone northwest of the reactor. It is interesting to note that Wednesday, March 30, the International Atomic Energy Agency (IAEA) said, “The highest values [of radiation] were found in a relatively small area in the Northwest from the Fukushima Nuclear Power Plant. First assessment indicates that one of the IAEA operational criteria for evacuation is exceeded in Iitate village.” Radiation will not distribute itself uniformly, as this announcement shows. The evacuation orders should take into account the distribution of radioactive material.
The past week has also been full of conflicting and confusing reports. Two things happened at the same time, and a lot of the press got confused. You will read many reports of radiation of 1000 millisieverts per hour (100 rem/hr) coming from pools of water. In fact, what actually happened is the meters they are using have a maximum reading of 1000 millisieverts and the actual radiation levels may be significantly higher. This is an extremely high level of radiation that will make it very difficult to implement repairs to the cooling systems. Radiation at these levels can lead to death if one is exposed for a few hours.
At the same time, there was a report of a high level of a short-lived isotope of iodine being found. This measurement was wrong and retracted. Unfortunately, much of the press confused these two stories. If the short-lived isotope of iodine had been in the water, it would have meant a reactor had gone critical, i.e., it was undergoing chain reactions. This is one of the nightmare scenarios that can play out. If there is meltdown, the fuel can collect on the bottom of the reactor in such a way that the reactor starts produce large quantities of heat through fission. That would make the situation many times worse than it already is.
As we can see from the reports, this is a complex problem. It is not going to be solved quickly.
There is, however, one piece of good news in all of the reports. I see no evidence that there have been any significant new releases of radioactive material into the air, so the radiation levels in the surrounding areas have been steadily dropping, as expected from radioactive decay.
• Please join the Baker Institute for a live webcast on Friday, April 8, of a panel discussion on the nuclear crisis in Japan. The event, which is hosted by the Baker Institute Science and Technology Policy Program and Energy Forum, will feature Professor Paul Padley, Dr. James Cox of MD Anderson Cancer Center, Baker Institute energy fellow Amy Myers Jaffe and Professor Erich Schneider of The University of Texas at Austin.
Paul Padley, Ph.D., is a professor of physics and astronomy at Rice University.