FUKUSHIMA
(left) Diagram of reactor shutdown review. (below left) IAEA Director General Yukiya Amano at the Fukushima accident site in July 2011 (P. Pavlicek/IAEA). (below) A group of international experts under IAEA auspices shown standing in front of Unit 3 of Fukushima Daiichi Nuclear Power Plant (G. Webb/IAEA)
melt and release radioactive fission products. Eventually, hydrogen accumulated in several of the reactors and exploded. The explosions caused significant damage to the reactors and the containment buildings surrounding them thereby allowing radioactive gases and particles to escape from the reactors. In the weeks and months following the
incident, engineers at Fukushima struggled to keep the fuel in the reactors and the spent fuel sufficiently cooled to prevent further significant releases of radioactive particles into the seawater and atmosphere. Finally, in December 2012, TEPCO declared that all units were in a cold shutdown status. This indicated that the probability of any future overheating of the fuel and subsequent release of significant amounts of radioactivity was very low.
Clean-up phases In December 2012, the Japanese government released a long term clean- up plan and roadmap for Fukushima.
Phase 1. Start removal of spent fuel from spent fuel pools of Units 1 – 4 (2014).
Phase 2. Complete removal of spent fuel from spent fuel pools and start removal of fuel debris from reactors (2022).
Phase 3. Complete fuel debris removal (2037) and complete decommissioning (2052).
Radiation levels Significant amounts of radiation were released to the air and water in the wake of the explosions and melting of the nuclear fuel at the Fukushima reactors. Elevated levels of radiation were detected in the areas around the reactors within a few days. Eventually, the Japanese government issued mandatory evacuation orders for those living within 20 km of the plant. Suggested evacuations for large portions of the surrounding area were put in to place due to concerns about spreading radiation. Indications of increased radiation levels were found throughout Japan. Sites as far away as the US and Europe also reported higher than normal levels of radiation due to the Fukushima incident. Despite the increased levels of radiation,
it appears that as of writing (April 2012) there have been no fatalities among the general public directly related to release of radiation from Fukushima. Recent studies indicate that very few
fatalities could be expected in the long term from radiation exposure to the public as a result of Fukushima. In March 2012, it was reported that no Fukushima residents had reported radiation-related ailments. Some workers at the plant received high
levels of radiation. Although there were a few fatalities among plant workers from non- radiation causes, none of those who received high levels of radiation has succumbed to date.
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Long-term effects Another concern is the long-term impact of radiation on the land and sea around the Fukushima facility. On 1 April 2012, the Japanese government announced that radiation levels within some parts of the 20- km evacuation zone had decreased to levels considered to be safe enough to allow people to return temporarily to repair their homes in preparation for an eventual full-time return. Farming activities will also be allowed in these areas. Other areas continue to have higher levels of radiation and are not expected to be deemed safe for return until 2016. The situation with ocean areas around
is similar. Radiation levels in the ocean area immediately around the plant are elevated and are expected to remain so for the foreseeable future. However, experts believe the strong ocean currents in the area of the plant will disperse much of the radioactivity to near background levels in the near future. While the short-term health impacts on the residents in and around Fukushima appear to be minimal at this time, the long-term effects will not be known for many years. The biggest impact will be remediating the areas in the evacuation zones that show elevated levels of radioactivity.
Richard L. Bigelow is a nuclear engineer with more than 25 years in the nuclear industry and is a patent attorney in private practice in the US. He is also a prime contracts manager with The Shaw Group.
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