Four nuclear accidents happened in less than 3 months in Japan in the same NPP and with the same reactor. The action took place 39 years ago, in the period January – March. The radiation leaks were from Japan’s first boiling water reactor, the one at Tsuruga Nuclear Power Plant (Central Japan), built in 1974 in 48 months. As a result of the incidents, authorities have officially notified 278 people have been exposed.
The series of accidents in early 1981 ended on March 8. Then, 16 tons of radioactive water flow from the cooling system of the first unit. The cause was a crack in a pipe that causes radiation to escape into the environment. 56 Tsuruga NPP employees have been exposed to radiation during this incident alone. What is even more terrible is that the accident has been covered up for 40 days.
The Tsuruga NPP is located in Fukui Prefecture. It is owned by Japan Atomic Power Company (JAPC). The area of the complex is 5.12 km2. There are two experimental reactors on the plant site: Fugen (decommissioned) and Monju. They are property of the Japan Nuclear Cycle Research Institute. Tsuruga NPP has two units and two more are under construction since 2017 and 2018.
An interesting fact is that the first accident occurred just a few months after the plant was opened. On October 1, 1974, 13 tons of radioactive water were discharged into the sea and 37 employees at the NPP were irradiated.
In 1994 at the Tsuruga Nuclear Power Plant, the experimental Monju reactor of fast neutrons for nuclear fuel reproduction was launched. Only a year later, strong vibrations in the second round of its cooling system cause the thermometric probe to break. Sodium leaks, causing a strong fire. Neither the alarm nor the automatic reactor shutdown system was triggered by the accident. The reactor has been stopped manually after about an hour and a half. Monju has been decommissioned for 14 years.
Five years after the incident, on June 12, 1999, another accident occurred and about 90 tons of radioactive water leakage from the second unit of Tsuruga NPP.
A number of other repair-related accidents were also discovered late, in which NPP personnel were exposed to high doses of radiation.
Japan’s Nuclear Energy Control Committee formally acknowledges in its 2013 report that a second unit of the Tsuruga NPP was built on an active fracture of the earth’s crust, which is prohibited by Japanese law, Kyodo news agency reported.
Translator: Valentina Vagge