information about Fukushima published in English in Japanese media info publiée en anglais dans la presse japonaise
6 Août 2014
There is an ongoing battle between the Sakurajima volcano and 50-km-away Sendai nuclear power plant in Kyushu, southwestern Japan. While the operator of the power plant aims to restart its idle nuclear reactors, a new strong eruption brings our attention back to issue of how safe our nuclear power plants are from the dangers posed by volcanoes.
Japan’s new safety standards set by Nuclear Regulation Authority (NRA) in 2013 now require electric power companies to consider possible influences from volcanoes located within a radius of 160 kilometers from nuclear power plants. Because of this, Sendai operators examined the effects of eruptions from 39 volcanoes in what is called Japan’s first serious evaluation of the safety of nuclear power plants from the standpoint of the danger posed by volcanoes.
As far as the volcanic ash is considered, the evaluation concluded that it is sufficient to take measures based on the assumption that ash from Sakurajima volcano in Kagoshima Prefecture would accumulate in the compound of the Sendai nuclear power plant to a height of up to 15 centimeters…
However, as noted by Asahi Shimbun, “will those measures really work given the possibility that accumulation of volcanic ash to a height of only several millimeters will seriously impede workers and vehicles? If the intake of water to cool nuclear reactors is also impeded, the reactors will be immediately plunged into dangerous situations.”
_It is assumed that catastrophic eruptions in Japan occur about once every 6 000 - 10 000 years but no one can exactly say when or where the next one will happen. On the other hand, it is known that when they do happen the pyroclastic flows can bury an area of over 100 kilometers from the volcano.
Such massive eruptions can cover the entire Japan and all surrounding countries in thick volcanic ash and should such event occur while the plant is operating, the control over the station would definitely be lost.
"The major pyroclastic currents produced by Kumamoto Prefecture’s Mount Aso about 90 000 years ago burned down the entire northern half of Kyushu and traveled across the ocean to what are now Yamaguchi and Ehime prefectures. Pyroclastic flows caused by Kagoshima Prefecture’s Mount Aira 26 000 to 29 000 years ago completely destroyed southern Kyushu. Such eruptions are particularly common in Kyushu and Hokkaido." (Mainichi)
In earthquake vs the nuclear power plant scenario that took place in 2011, the earthquake definitely won. Such strong quakes are considered to happen once every 1 000 years but can science really say that Japan (and the rest of the world) is safe for the next 1 000 years?
Sakurajima erupts several hundred times per year.
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http://ajw.asahi.com/article/views/editorial/AJ201405120021
May 12, 2014
Now is the time to rethink the risk of operating nuclear power plants in Japan, which is one of the most volcanically active countries in the world.
Kyushu Electric Power Co. is currently aiming to restart the operations of idled reactors in its Sendai nuclear power plant in Kagoshima Prefecture. However, in the Nuclear Regulation Authority's inspection process on whether to permit the restarts, the possible consequences of volcanic eruptions in surrounding areas is attracting attention.
Based on the new safety standards worked out in 2013, the NRA is examining the threat posed by eruptions and the effectiveness of measures to deal with them. To tell the truth, it is the first time that Japan has seriously evaluated the safety of nuclear power plants from the standpoint of the danger posed by volcanoes.
In the March 2011 accident at the Fukushima No. 1 nuclear power plant, people in charge had to reflect on the insufficient measures to deal with tsunami. However, disasters at nuclear power plants could be caused not only by tsunami but also by volcanic eruptions and even terrorists. Given the seriousness of disasters caused by these factors, it is a matter of course to think seriously about the risks posed by them, which have been made light of so far.
The new safety standards require electric power companies to consider possible influences from volcanoes located within a radius of 160 kilometers from nuclear power plants. Therefore, Kyushu Electric examined the effects of eruptions from 39 volcanoes. As a result, it concluded that it is sufficient to take measures based on the assumption that ash from Sakurajima volcano in Kagoshima Prefecture would accumulate in the compound of the Sendai nuclear power plant to a height of up to 15 centimeters.
As one of the measures, the utility will stockpile fuel for emergency generators in preparation for a situation in which power transmission lines were severed due to the weight of volcanic ash. Another measure is that it will clean filters for air ventilation equipment or emergency generators or replace the filters with new ones if they become clogged.
However, will those measures really work given the possibility that accumulation of volcanic ash to a height of only several millimeters will seriously impede workers and vehicles? If the intake of water to cool nuclear reactors is also impeded, the reactors will be immediately plunged into dangerous situations.
The influences from these mid-scale eruptions must be fully examined as realistic threats.
It is more difficult to assess risks from catastrophic eruptions whose frequency of occurrence is low.
In those eruptions, the pyroclastic flow, which consists of hot gas and rock, travels more than 100 kilometers, causing devastating damage in surrounding areas. In the areas around the Sendai nuclear power plant, there are several calderas, or bowl-shaped depressions, that were formed by the collapse of land caused by catastrophic eruptions.
Kyushu Electric assessed that, given those calderas, catastrophic eruptions have occurred at an interval of about 60,000 to 90,000 years. Based on the assessment, it says, “Not much time has passed since the latest catastrophic eruption occurred. Therefore, the possibility is extremely low that the next catastrophic eruption will take place within the coming several decades when the nuclear power plant is operating. There will be no problems if we continuously monitor the signs of eruptions.”
However, some experts offer contrasting views, saying that forecasts of the intervals of eruptions are not reliable and that it is uncertain whether the signs of an eruption can really be foretold.
Nuclear power plants are not the only facilities that would suffer devastating damage from catastrophic eruptions. If those nuclear plants are destroyed, however, radioactive materials will continue to be scattered throughout the world. It is a challenge not only for the Sendai nuclear power plant but also for many other nuclear power plants in Japan.
Methods to assess the possible impact of eruptions have yet to be established in the world. The NRA bears responsibility for conveying the potential consequences, including the limits of human knowledge as to forecasting eruptions, to the public in an easy-to-understand manner.
--The Asahi Shimbun, May 11
Blogpostby Kazue Suzuki - 16 July, 2014 at 14:32
The decision of the Nuclear Regulatory Authority (NRA) to approve the draft assessment for the two Sendai nuclear reactors in Kyushu is a clear and dangerous signal that Japan's nuclear village – industry, regulators and government – is deliberately and cynically ignoring the lessons of the Fukushima nuclear disaster. The approval of the assessment is the first step in restarting the Sendai reactors.
The two Sendai reactors have been shutdown since 2011. These are old reactors – 29 and 30 years respectively. Nuclear reactors, no matter what age, are inherently at risk of an accident, but the older the plant the greater the risk. A car designed four decades ago and operating for 30 years in no way can meet safety standards of the present day. Fukushima has shown again that nuclear reactors have the potential to devastate a region and its people.
The citizens of Japan know that the Sendai reactors are not safe to operate. When the NRA announced it was putting the reactors at the top of the list for review, 6000 people demonstrated in Kagoshima near the plant. According to an opinion poll by Greenpeace Japan, less than 10% of the people living within a 30km radius of the Sendai nuclear power plant think they can evacuate without being exposed to radiation if a severe nuclear accident were to occur.
Last week, Aira city councillors voted 23 to 1 against restarting the Sendai reactors. Aira, in Kagoshima Prefecture, lies only 30km from the Sendai nuclear reactors, and is a designated evacuation point in the event of a severe accident.
The regulators have accepted the view of Kyushu Electric Power Company, the Sendai operator, that the seismic and tsunami risks are low at the site. This is despite a warning from independent seismologists that the science of earthquakes is such that it is not possible to predict where an event will happen and its strength. No tsunami sea wall has been built at the Sendai plant.
The major issues of concern at Sendai include: no effective evacuation plan for the populations in the region, no functioning emergency response centre protected against radiation, and the failure of Kyushu Electric and the NRA to conduct robust assessments on volcano risk.
Like many nuclear plants in Japan, Sendai is close to an active volcano – in this case, Sakurajima, one of the most active volcanoes in the world, and one of the few that are at present in constant (persistent) activity. This volcano is about 70km from the Sendai nuclear plant. Ongoing, typical activity ranges from strong strombolian (low-level eruptions) to large ash explosions every 4-24 hours.
The Sakurajima volcano is of major concern to many experts, including vulcanologists, with the threat that in the event of an eruption, it could take out offsite electric power to the plant. The same eruption could clog the air intakes of diesel generators, the only source of ongoing power if the offsite power is taken out of service. A station blackout was what led to the loss of cooling function at Fukushima and the subsequent reactor meltdowns.
The nuclear village in Japan was one of the principal reasons why the Fukushima accident took place. While the Abe administration and nuclear industry may prefer to forget the lessons of 2011 the people of Japan will not. They are determined to stop the planned restart of Japan's nuclear reactors.
As we approach the one year birthday of no nuclear-powered electricity in Japan (the last of the country's remaining 48 reactors were shutdown in September 2013) it is clear that Japan can function as a society without risking catastrophic nuclear accidents, while rapidly growing its renewable energy sector and embracing efficiency. The NRA decision may make headlines around the world but Japan is a long long way from restarting its large nuclear program – and the people of Japan are determined to make its future energy path a very different one from its past.
Kazue Suzuki is a Nuclear and Energy Campaigner at Greenpeace Japan.
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