The earthquake that occurred in Japan was magnitude 8.9 on the Richter scale. Aside from the damage caused to Japan's infrastructure from the earthquake, a ten-meter high tsunami flooded the northeastern coastline of the island. As of today, 1,597 people are reported dead, 1,923 injured, and 1,481 people missing across sixteen regions but these estimates may soon rise in the next few days.
There has also been widespread panic over the state of Japan's nuclear power stations. Several nuclear facilities have been severely damaged in addition to the rest of Japan's northern industrial centers. Because of the shoddy reporting from the media as is typical with anything concerning nuclear energy, it is difficult to sort out fact from fiction. As people are already comparing what is happening in Japan with Chernobyl, I feel that it is important that I try and clear up any dangerous inaccuracies.
The Fukushima Daiichi facility
This station is in the town of Ōkuma, on the northeastern part of the island of Honshū. It is composed of six boiling water reactors, leading to a combined power output of 4.7 gigawatts. All six of the reactors have suffered damage but in varying degrees.
Unit-1 (SCRAMed) is the oldest reactor on-site. Because of its age, it was originally scheduled to be decommissioned in roughly two weeks after this blog post was written. Water used to cool the reactor came in contact with the superheated fuel rods, causing instant vaporization and separation of the water into hydrogen and oxygen gas. The hydrogen built up and ignited resulting in an explosion that has destroyed the concrete shell over the reactor vessel, but the vessel itself remains intact. The reactor also suffered from a loss of cooling after on-site generator failure from the impact of the tsunami. The reactor SCRAMed (Automatically shut down) during the coolant flow malfunction, but borated seawater has been used to cool the reactor because of the residual heat still coming from the core. The reactor itself is probably damaged beyond practical repair, but temperature and pressure levels remain under control, and the containment dome remains intact.
Unit-2 (SCRAMed) has switched to auxiliary cooling in the wake of the tsunami, and the reactor itself remains in good condition. However, the turbine, generator, and surrounding machinery have been badly damaged. It is likely that Unit-2 will be able to be restarted after it has been repaired.
12:02 AM (CST) Update: The auxiliary coolant system seems to have failed and an explosion has occurred. It is not yet known what the cause of the explosion was, but steps have been taken to cool the reactor core with borated seawater as with Unit-3 and Unit-1. The containment dome remains intact and undamaged.
Unit-3 (SCRAMed) suffered a temporary loss of cooling similar to that of Unit-2, but recent investigation has revealed that auxiliary cooling systems have taken over. The safety release valve has been opened by workers to relieve pressure. Borated water has been injected into the reactor vessel to reduce the residual heat of the reactor core.
1:55 PM (CST) Update: An explosion of hydrogen gas similar to the incident at Unit-1 has occurred at Unit-3 at 11:01 AM JST (9:01 PM CST). The reactor vessel is still thought to be intact, but it is not yet known what the overall status of Unit-3 is and how much radiation, if any has been released into the outside environment. The effects of the explosion are still being investigated.
11:57 PM (CST) Update: Unit-3 has been written off as a loss as the borated seawater will irreparably damage the reactor. However auxiliary cooling systems have been inadequate so operators are going to have to resort to such measures to reduce the heat of the reactor core. A partial meltdown did occur but the containment dome remains intact and no significant amount of radiation has escaped from the core.
Unit-4 has been shut down in order to allow for inspection. Coolant levels are adequate and there appear to be no signs of leakage and the containment vessel seems to be intact.
3-15-2011 12:02 AM (CST) Update: A small fire has been reported at Unit-4. It has been contained and extinguished without incident.
3-15-2011 12:05 PM (CST) Update: The fire appears to have resulted from the cladding of Unit-4 igniting after coolant levels covering the bundle of fuel rods has dropped, allowing heat to build up. As the reactor was only recently shut down, the temperature of the fuel rods was much higher than if the reactor had been shut down a few days ago. Some radioactive material might have been released with the evaporating water surrounding the core, but the quantity and concentration is still unknown and it is likely that the danger level is small to nonexistent.
Unit-5 has been shut down in order to allow for inspection. Coolant levels are adequate and there appear to be no signs of leakage and the containment vessel seems to be intact.
Unit-6 has been shut down in order to allow for inspection. Coolant levels are adequate and there appear to be no signs of leakage. The containment vessel seems to be intact.
The degree of radiation in the immediate vicinity of the plant has increased. Small amounts of radioisotopes were dissolved in the steam vented to relieve pressure inside the reactors at Fukushima Daiichi. However, this is not a cause for concern as the concentration of these isotopes within the steam is very low, and most of them are very weakly radioactive. Determining the actual levels of radiation released by the nuclear facility can be problematic, because elevated radiation levels can also be attributed to the naturally occurring radioisotopes found in ash from fires and other particulate matter that has been swept into the area.
To date, there have been no deaths at Fukushima Daiichi, but ten employees have received medical attention and two workers are reported missing. Three workers have been reported to have been exposed to abnormally high doses of radiation, but I have not found any reliable information yet concerning the details of how much radiation they were exposed to, and what the source was thought to be. Despite the alarmism, there have been no credible reports of the nearby populace being contaminated with radioactive fallout.
3:31 AM (CST) Update: There has been one death at Fukushima Daiichi in an accident during the operation of a crane, yet it is unrelated to the incidents at the reactors themselves.
The Onagawa Facility
The Onagawa nuclear station is located near the town of Onagawa on the island of Honshū. It consists of two 825 megawatt reactors and one 524 megawatt reactor. The earthquake damaged the generator and turbine systems, causing all three of the reactors to SCRAM even though the reactors themselves sustained minimal damage and cooling systems remain intact. A fire occurred in Onagawa-3 resulting from a malfunctioning turbine but it was immediately controlled and put out without incident. No casualties at the Onagawa nuclear power station have been reported.
The Higashidōri Facility
The nuclear power plant near the town of Higashidōri is located on the northern tip of Honshū. It consists of four units, with Higashidōri-1 and the planned Higashidōri-2 being controlled by the Tōhoku Electric company, while the other two reactors planned to be built on-site are run by Tōkyō Electric. Higashidōri has been shut down following the disaster to carry out inspection and maintenance. The extent of the damage, if any, at Higashidōri remains unclear but no reports have surfaced concerning the failure of any critical systems. However, the earthquake might have damaged the three reactors at Higashidōri that are still in the construction phase. No casualties at Higashidōri have been reported.
The Tōkai Facility
This nuclear power station is in Tōkai on the central-eastern coast of Honshū. Unit I had reached the end of its operating license and was decommissioned while Unit II remained operational. The reactor SCRAMed during the earthquake, but the auxiliary cooling system took over. No casualties at Tōkai have been reported.
The Rokkasho Reprocessing Center
While not a nuclear power generating facility in of itself, this is where Japan fabricates most of its fuel for its nuclear power stations and reprocesses spent material. Although it does not appear to have suffered any catastrophic damage, it is currently running on auxiliary power because of the loss of electricity to much of northern Honshū. Normal operation has been suspended until primary power comes online. No casualties have been reported.
This is currently what I have found out about in the aftermath of the earthquake and the following tsunami in Japan. I have also heard of an eruption of the Shinmoedake volcano but it is not yet clear if it was triggered by the earthquake in Sendai. I welcome any comments suggestions, or updates on the current status of Japan's nuclear infrastructure in the coming days.