The Tsuruga Nuclear Power Plant (敦賀発電所, Tsuruga hatsudensho; Tsuruga NPP) is located in the city of Tsuruga, Fukui Prefecture, Japan. It is operated by the Japan Atomic Power Company (JAPC). The total site area is 5.12 square kilometres (1.98 sq mi) with 94% of it being green area that the company is working to preserve. The Tsuruga site is a dual site with the decommissioned prototype Fugen Nuclear Power Plant.
Construction of two new nuclear reactors is currently planned. However, there have been several delays due to the need for seismic upgrades, even before the March 2011 earthquake. As of 2014, construction has not begun on the two new reactors, although a tunnel has been completed linking the tip of the peninsula with the existing Units 1 and 2 sites.
The Tsuruga 1 reactor is the oldest commercial reactor in Japan.
It was shut down for a safety inspection on 26 January 2011.
In March 2015 JAPC announced that Tsuruga 1 would be decommissioned.
In March 2015 the Nuclear Regulation Authority (NRA) accepted an expert report that concluded the plant is on an active fault, which put any restart of Tsuruga 2 in doubt.
In March 1981, drainage from unit 1 caused a release of radioactivity. The forty-day cover-up of a spill of 16 tons of radioactive primary cooling water was revealed only in April.
On 2 May 2011, Kyodo officials announced higher levels of radioactivity in the cooling water, JAPC admitted technical problems and announced to check for radioactivity on a daily basis from now on, instead of checking only every week, what has been standard procedure up to now.
On 12 November 2011 at 7:45 PM local time a fire broke out in the No. 1 reactor. After a switch for a spare electrical device at the water processing facility was operated by a worker, the fire was ignited because a short circuit caused a series of hot sparks. After the fire was put out, no casualties were reported. JAPC said that there was no leakage of radiation, because the reactor was closed for inspection.
Juridical actions of citizens against restarting the nuclear reactors
On 8 November 2011 a group of 40 citizens of Otsu in Shiga prefecture started a lawsuit at the Otsu District Court against Japan Atomic Power Company. They asked for a provisional court order to delay the restart of the two reactors at the Tsuruga Nuclear Power Plant in the city of Tsuruga. The plaintiffs argued that the plant is unsafe being built on a fault, and a severe accident could occur during an earthquake endangering the health of all residents, also contaminating Lake Biwa.
They also criticize the government's safety and technological standards and regulations.
Seismic research done in 2005, 2011 and 2012
On 5 March 2012, a group of seismic researchers revealed the possibility of a 7.4M (or even more potent) earthquake under the Tsuruga Nuclear Powerplant. Before this date, the Japanese governmental Earthquake Research Committee and Japan Atomic Power had calculated that the Urasoko fault under the plant, combined with other faults connected to it, was around 25 km long. and could cause a 7.2M quake and a 1.7 meter displacement. On top of this, the presence of the oceanic faults were not taken into account by NISA and JAP in the assessment of the safety of the Tsuruga nuclear power plant.
Analysis of sonic survey and other data provided by Japan Atomic Power analysed by a panel of experts of Nuclear and Industrial Safety Agency showed the presence of multiple faults existing within 2 to 3 km from the Urasoko fault. According to Yuichi Sugiyama, a member of this group of scientists, these faults were highly likely to be activated together, and this would extend the length of the Urasoko fault to 35 km.
Computer-simulations calculating the length of a fault based on its displacement, showed the Urasoko fault to be 39 km long, a result close to the length estimated by the sonic survey data, and the fault could cause some 5 meter displacement when activated together with other faults.
Sugiyama, the leader of this research group of the National Institute of Advanced Industrial Science and Technology, warned that – as other faults on the south side of the Urasoko fault could become activated together – "The worst-case scenario should be taken into consideration".
According to the experts, there were many other faults located under one reactor on the west side of the Urasoku fault that could also move simultaneously. If this would be confirmed, the location of the Tsuruga nuclear plant would be disqualified.