Bieudron Hydro Project
The Bieudron Hydroelectric Power Station is a hydroelectric power plant located in the Swiss Alps in the Canton of Valais in Switzerland. The power plant is fed with water from the Grande Dixence Dam's reservoir, Lac des Dix and is part of the Cleuson-Dixence Complex. The 1269 MW power plant is operated by Grande Dixence SA.
Production began in 1998, with two world records set upon its completion: the world's most powerful Pelton turbine as well as the highest head used to produce hydro-electric energy. A rupture in 2000 forced the closure of the power plant and it was operational again in 2010.
This facility houses three Pelton turbines, with each turbine rated at 423 MW (~567,000 HP); note that the turbine acceptance testing process reported a maximum turbine output power of 449 MW each (~602,000 HP) due to better than expected efficiency and ideal test conditions.
At the rated power of 423 MW each turbine operates at a head of ~1869 meters (6130 feet) and a flow rate of 25 cubic meters per second, with an efficiency in excess of 92% (~92.37%). The turbine assembly is a five-jet configuration; the stream of each jet is 193 mm (7.6 inches) in diameter with an exit velocity of 192 meters/second (630 ft/s). The kinetic energy of each of the 5 streams (i.e. 1 from each jet) is approximately 92.16 MW (Q = 5 cubic meters per second, v = 192 m/s, H = 1869 m). The assembly rated pressure is 203.2 bars (2944 psi).
The combined flow rate for the three turbines is 75 cubic meters per second. The facility peak power production is ~1269 MW. The turbines and associated valves were designed and developed by VA Tech of Switzerland.
On December 12, 2000, at approximately 20:10, the Cleuson-Dixence , feeding the Pelton turbines at Bieudron, ruptured at ~1234 meters AMSL (under more than 1000 meters of head). The failure appears to have been due to several factors including the poor strength of rock surrounding the penstock at the rupture location. The rupture was approximately 9 m long by 60 cm wide. The flow rate through the rupture was likely well in excess of 150 m3/s (5,300 cu ft/s). The ensuing rapid release of a very large quantity of high pressure water destroyed approximately 100 hectares (1 km²) of pastures, orchards, forest, as well as washing away several chalets and barns around Nendaz and Fey. Three people were killed.
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