Complete destruction of nuclear-related facilities Caused by corrosion of wooden braces
For nuclear facilities in Ibaraki that were completely destroyed by the typhoon in September, the Japan Atomic Energy Agency has compiled the results of the investigation that the wooden braces of the building were corroded and collapsed by half the design standards. It was. The JAEA has many other facilities that were built in the Showa era, and countermeasures against aging are an issue.
At the Oarai Research Institute of JAEA in Oarai-machi, Ibaraki Prefecture, a typhoon No. 15 in September completely destroyed a building about 17m high that cools the research reactor.
At that time, the maximum instantaneous wind speed on the premises was only about 30 meters, which is about half of the design standard for this building, so the JAEA was investigating the cause of the collapse in detail.
As a result, it was found that some of the wooden braces that supported the building were corroded, and simulations based on that confirmed that they collapsed with wind below the standard.
The facility was completed in 1968 and it has been 51 years old, and it has already been abolished and there was no radioactive material. However, asbestos was contained on the outer wall, and there was a possibility that a minute amount would be scattered when collapsed.
It means that they were regularly inspected, but they did not notice the corrosion because the surface of the wood was covered with metal.
According to the JAEA, 89 facilities nationwide have become obsolete, and 70% of them are over 40 years old, so we want to consider measures to prevent recurrence such as reviewing inspection methods.
Limited budget Agenda for aging
The Japan Atomic Energy Agency, the National Research and Development Corporation, was established in 1948 and has been conducting basic research on nuclear energy.
▽ Dynamic combustion, which was established in 1967 and has been responsible for the development of new nuclear power plants = an organization formed by integrating the successor organization of the "Power Reactor and Nuclear Fuel Development Corporation", an old research facility in Showa when nuclear power was introduced Many remain.
In addition to Ibaraki, Fukui Prefecture, Okayama Prefecture, Hyogo Prefecture, Gifu Prefecture, Fukushima Prefecture, Aomori Prefecture and Hokkaido have laboratories and other facilities. There are 89 facilities.
About 70% of these are already over 40 years old.
According to JAEA officials, while old facilities are being inspected and demolished one after another, there are limits to the costs that can be covered within the limited national budget. The issue is how to take measures against aging.