Sunday, April 10, 2011

Follow Up on Fukushima Daiichi

The situation at the Fukushima Daiichi reactor is largely under control. Although I have been dismayed by the degree of exaggeration and outright falsehoods that were evident in the coverage on the status of the Fukushima Daiichi reactor, I should not have been surprised considering how ignorant the general public often is about how nuclear reactors work and what measures are in place to ensure the safety of the workers and the surrounding area when something goes wrong. The electricity provided to Fukushima Daiichi by emergency diesel-powered generators was not affected from the second earthquake on April 7th. A leak near Unit-2 has been sealed, preventing the further release of water contaminated with highly radioactive nuclides. The source of radioactivity is unknown at this time.

The spraying of water on the exposed fuel assemblies within Units -1 through -4 continues and nitrogen gas is being pumped into Unit-1 in order to prevent any further explosions involving hydrogen gas build up. Makeshift dams out of silt and steel plates are being installed in the ocean surrounding the reactor site in an attempt to contain some of the mildly contaminated water that was released offshore. While the risk to civilians and most personnel from radiation exposure has been minimal since the beginning of the incident, radiation levels surrounding the site continue to drop dramatically, and the Japanese government has lifted restrictions on consuming milk and produce from farms surrounding Fukushima Daiichi as of April 8th.

Here are some numbers detailing the total casualties that have resulted from Fukushima Daiichi since the first earthquake, courtesy of the Depleted Cranium blog:

Deaths: Two workers died from injuries resulting from the first earthquake, which was unrelated to the operation of Fukushiima Daiichi itself.

-Update: A third worker died on May 14 as he was an older man in his 60's and he had an underlying heart condition that was aggravated when he was carrying construction materials at the plant. This was unrelated to radiation exposure or the operation of the facility itself.

Injuries: Twenty three workers have been injured at Fukushima Daiichi. Eight of those people were involved in accidents involving the operation of non-nuclear equipment during the earthquake while fifteen people have received minor injuries during the hydrogen explosions shortly after the earthquake. Two people have received minor radiation burns that did not require further treatment after being evaluated at a hospital.

Radiation Exposure: Seventeen workers had to undergo radiation decontamination procedures on-site after minor radiation exposure, but not enough to warrant further decontamination measures off-site.

Prognosis For Workers Exposed to Minor Radiation: Excellent, possibly a slightly increased risk of developing cancer but this is statistically negligible when compared to the probability of developing cancer as a function of age for the average person in the general population.

Effects on the General Public:

Injuries to the General Public: None

Casualties Resulting From the Earthquake and Tsunami: 30,000 and counting.

Radionuclides in the Water Table:

There has been some discussion about the safety of Japan's water supply in regards to contamination by iodine-131. There have been warnings issued about the levels of iodine-131 recorded in Japan's water supply on the twenty-third of March as they were above the 100 Bq/Kg (Becquerels per kilogram) limit set by Japan for infants, but still well below the 300 Bq/Kg limit for adults. Japan's guidelines for exposure to iodine-131 are also extremely conservative as the WHO's limits for iodine-131 are 3,000 Bq/kg. In any case, levels of iodine-131 in the water table have dropped dramatically since March 23rd because iodine-131 has a half-life of only eight days and the levels of iodine-131 have been below the Japanese 100 Bq/Kg limit for infants since the 24th of March.

Now, with all of this being said I hope that we can all put our fears of nuclear power to rest as many of them were unwarranted and there is also the fact that the incidents at Fukushima were relatively minor when one considers the fact that the structure was designed to survive earthquakes at a maximum of 8.0 on the Richter scale when the first earthquake that hit the island of Honshū was 8.9. If Fukushima had been any other sort of power-generating structure, the potential for casualties would have been much higher as natural gas and coal generating facilities are prone to explosions, and hydroelectric dams often break during earthquakes. The problems at Fukushima should serve to reinforce the lesson on how safe nuclear energy really is considering the intensity of the earthquake.

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