Onagawa Nuclear Power Station

Onagawa Nuclear Power Station
Onagawa-cho, Osika-gun and Ishinomaki City, Miyagi Prefecture


A Profile of the Nuclear Power Station

The onagawa nuclear power station is located in both Onagawa-cho and Ishinomaki City, along the coast of the Pacific Ocean, 70 km to the north of the Sendai City. The site area is about 1,730,000 sq. meters. The site was excavated to place the buildings of the station on deep rigid bed-rocks and artificial rocks. From the beginning, the main buildings of the Onagawa Station, such as the reactor buildings, the turbine buildings and the control building, have been arranged in consideration of nature. In January of 2001, the facilities obtained ISO14001 certification, an international standard related to the environment.

Unit No. Capacity
1 524 BWR Jun. 1984 Toshiba
2 825 BWR Jul. 1995 Toshiba
3 825 BWR Jan. 2002 Toshiba/


-Thermal Effluent Countermeasures-
Cooling seawater, after passing through the main condenser, is discharged into the sea as thermal effluents about 7°C warmer than ambient water at the outlet. An underwater outlet, about 10 meters below the surface, is used for discharging thermal effluents to reduce their influence on the ecosystem of the neighboring sea area. figure
Predicted Diffusion Range Diagram Thermal Effluents

figure Cross Section of the Predicted Diffusion Range Diagram


The power station is located on the Oshika Peninsula near Matsushima, one of the three best scenic places in Japan. The peninsula, jutting out into the Pacific, contains Minami Sanriku Kinkazan Quasi-National Park where visitors can enjoy a magnificent view of the Cobalt Line road, a 30-km-long Rias coast. Off the tip of the peninsula is Kinkazan Islet which is known as the site of the first gold mine in Japan. The islet is covered with virgin forests, so visitors can enjoy watching herds of wild deer and monkeys and a scenic view of white rocks and the blue sea.