Okutadami Dam

The Okutadami Dam (Japanese奥 只見 ダム, Okutadami - damu ) is a dam on the Tadami in Japan. The concrete gravity dam is 26 km east of Uonuma on the border between the two prefectures of Niigata and Fukushima. The main purpose of the dam is generating electricity in a hydroelectric power plant, which is at nominal power of 560 MW, one of the largest in Japan ( excluding pumped storage power plants ). Also the reservoir is one of the largest in Japan, after the Tokuyama.

History

In the first phase of a 360 - MW power plant was completed and put into operation on December 2, 1960. The remaining construction works ended in 1961., The plant was expanded between 1999 and 2003 by an additional 200 MW were installed. In addition, a 2.7 MW generator was added to ensure a minimum for environmental reasons outflow of 2.5 m³ / s.

Specifications

The Okutadami - shut-off is a 157 m high and 475 m long dam with a concrete volume of 1.636 million m³. She stands at the end of a 595 km ² catchment area and creates a reservoir with 601 million cubic meters of storage capacity, of which 458 million m³ of usable space. The water surface is 1150 ha. The power plant is located underground on the right bank below the dam. It consists of two underground caverns, an original for the power plant and one for the extension. The water for the old power plant flows behind the intake structure by three 185 to 189 m long pressure pipes before each reaches its own 120 - MW Francis turbine with a generator. The newer 200 - MW Francis turbine-generator receives its water through a 280 m long pressure tube. After the water has passed through the generators, it flows through two drainage tunnels before there will be 3 km downstream drained to the top of the Otori Reservoir. The hydraulic drop height is 170 m for the three 120 -MW units and 164.2 m for the 200 - MW unit.