Japan: Nuclear plants must take threat of volcanic ash more seriously

The Nuclear Regulation Authority will reassess the safety risks posed by possible natural disasters to certain nuclear power plants that have been declared to be fit for operation under the new safety standards.

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Using research findings and geological surveys as well as simulations of eruptions of Mount Daisen, a volcanic mountain in Tottori Prefecture located about 200 kilometers from the plants, the Osaka-based utility estimated that the nuclear compounds could be coated with up to 10 centimeters of ash from a major volcanic eruption.

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After the NRA’s safety screenings, however, a 30-cm ash layer from an eruption of Mount Daisen that occurred 80,000 years ago was discovered in Kyoto, 190 km from the mountain.

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A massive fall of volcanic ash could cause a malfunction of the emergency power generation system at a nuclear power plant and cut off the power supply, which is crucial for preventing a severe nuclear accident during a natural disaster.

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Kansai Electric Power’s response to the new discovery deserves to be criticized as an attempt to escape from an inconvenient new fact.

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