10 Septembre 2014
September 8, 2014
The Nuclear Regulation Authority (NRA) has released a "basic concept" for dealing with major volcanic eruptions threatening the nation's nuclear power plants. If abnormal volcanic activity posing a threat is detected near a nuclear plant, the regulatory body will ask the power company in charge to halt the plant's reactors and remove nuclear fuel -- even if it might turn out to be a false alarm. The NRA is set to convene a meeting of experts to determine standards for taking such action.
Experts are aligned on the view that the No. 1 and 2 reactors at Kyushu Electric Power Co.'s Sendai Nuclear Power Plant in Kagoshima -- recently judged by the NRA to meet new safety standards -- together face the greatest risk of being damaged in a major volcanic eruption. This should have been considered before the plant underwent safety screenings. Japan is one of the most volcanic countries in the world, and neither the NRA nor the nations' power companies should make light of the threat of eruptions.
The landscape around the Sendai plant is marked by calderas -- cauldron-like geographical features that form when a large amount of magma spews out from under the ground, causing it to collapse. Mount Aso and Kagoshima Bay are two examples. In Japan, a major caldera-forming eruption is said to occur about once every 10,000 years.
Nuclear safety regulations established last year require power companies to conduct surveys on the possible effects of eruptions of volcanoes located within 160 kilometers of any nuclear power plant. Under the regulations, if there is a chance that an eruption could occur while the plant is in operation and produce a pyroclastic or lava flow that reaches the plant, then the land will be deemed unfit for nuclear power generation, and the plant will not be able to operate.
Kyushu Electric Power Co. has said the chance of such an eruption occurring while reactors at the Sendai plant are in operation is "sufficiently low." It says the plant could endure an eruption of the Sakurajima volcano that produced 15 centimeters of volcanic ash. Additionally, it says that even if a major eruption were to occur, then magma would build up several decades in advance, and if changes in the earth's crust were observed, then officials could perceive the danger.
In its safety evaluation, the NRA basically accepted Kyushu Electric Power Co.'s arguments. However, during a subsequent meeting of experts, it was pointed out that it is difficult to predict the size and timing of a major eruption. An opinion was also put forward that measures should not be left entirely in the hands of power companies but be addressed at the national level.
There are many nuclear facilities around Japan that could be affected by volcanic eruptions. The Sendai Nuclear Power Plant is a benchmark for those facilities in measures against eruptions.
NRA Commissioner Kunihiko Shimazaki, who currently serves as acting chairman of the regulator, says he doesn't know how far the body can go in setting standards for decisions pertaining to major eruptions. But unless officials remain on the safe side when forming standards, there could well be confusion when responding to an abnormality. Of course, if a major eruption does occur, it could threaten Japan's very existence.
In May last year, a Cabinet Office panel advised that monitoring be stepped up and evacuation plans quickly formulated, due to fears that volcanic activity could increase as a result of the March 2011 Great East Japan Earthquake. At the same time, delays in research on major eruptions have been pointed out.
To avoid an "unexpected event" such as the Fukushima nuclear disaster, we hope officials will take NRA's planned formulation of standards for its decisions as an opportunity to promote research and countermeasures against major volcanic eruptions.
September 08, 2014(Mainichi Japan)
September 2, 2014
The Nuclear Regulation Authority (NRA)'s expert panel on Sept. 2 released the "draft of basic views" designed to help prepare for huge volcanic eruptions around nuclear power plants in Japan.
The nuclear regulator will order the operator of a nuclear power plant to stop running the facility when it detects signs of abnormal volcanic movements, among other measures. But because the NRA leaves monitoring work to detect such signs up to the operators of nuclear power stations, the question is likely to be raised over whether the nuclear regulators will in fact be able to make proper judgments.
The NRA presented the draft proposal to its panel in which experts were taking part. According to the proposal, when the operator of a nuclear power plant observes abnormal movements that could lead to a caldera eruption or a huge volcanic eruption, the NRA will order the operator of the nuclear power station to stop the operation of the facility and remove nuclear fuel, among other steps. Acknowledging that "there is a limit to detecting abnormality through monitoring," the draft proposal says that measures which take into account the possibility of a volcanic eruption should be taken while being prepared for the possibility of such predictions turning out to have been off the mark. It also says, "The NRA will responsibly judge (whether a huge volcanic eruption will occur)."
Nevertheless, Setsuya Nakada, professor at the University of Tokyo, said, "It is unreasonable to leave all of the monitoring work to plant operators. A framework should be created at the national level." Hiroshi Shinohara, chief researcher at the National Institute of Advanced Industrial Science and Technology, said, "It does not clarify who will decide the criteria for determining volcanic eruptions and how they will be set."
Kunihiko Shimazaki, acting chairman of the NRA, acknowledged that there was more work to be done about the criteria, saying, "We are not sure to what extent, but it is necessary to set it."
The NRA has effectively judged that the measures against volcanic eruptions being taken by Kyushu Electric Power Co., the operator of the Sendai Nuclear Power Plant in Kagoshima Prefecture, are compatible with its new nuclear regulations. During the NRA's screening of the nuclear power station, which is seen as the first among the country's idled nuclear plants to go back online, suggestions emerged that there was a high possibility that pyroclastic flows triggered by volcanic eruptions in the past had reached the area where the nuclear complex currently sits. Therefore, the question has been raised about the credibility of the screening.
Furthermore, with respect to measures against volcanic eruptions at Mount Fuji, Chubu Electric Power Co. applied for safety assessments of its Hamaoka Nuclear Power Station in Shizuoka Prefecture in a bid to restart the facility, saying, "Even if Mount Fuji were to erupt, it would not damage the safety functions of the power station." The NRA is to examine whether the power station is capable of withstanding such volcanic hazards.
September 03, 2014(Mainichi Japan)
Sep. 2, 2014 - Updated 14:44 UTC+2
Japan's nuclear regulator is set to work on criteria for determining levels of volcanic eruptions that would affect nuclear power operations.
The Nuclear Regulatory Authority, or NRA, requires nuclear power plant operators to take specific measures if volcanic activity could affect operations. The measures include removing nuclear fuel from the facilities.
The NRA held a meeting on Tuesday with volcanologists to discuss how to deal with what might be seen as signs of massive volcanic eruptions.
NRA officials pointed out the need for the authority to fulfill its responsibility to determine unusual phenomena as signs of volcanic eruptions.
One of the volcanologists said the nuclear regulator or utilities alone cannot determine any such signs, stressing the need for cooperation with local volcanic observatories and government agencies.
Another expert said criteria should be established on multiple items so that they can be implemented in an uncompromising manner.
NRA Commissioner Kunihiko Shimazaki said it's necessary to formulate new criteria by reflecting the latest achievements in studies on volcanic activity.
The regulators agreed to consider concrete criteria to be established in about a year.