ITANAGAR, India 11/30/11 (PennWell) -- Developer KSK Energy Ventures Ltd. of India and Russian designer JSC Institute Hydroproject have agreed to the main parameters of a downsized 1,800-MW Subansiri Upper hydroelectric project to be built on India's Subansiri River.

KSK awarded a design contract for Subansiri Upper to Institute Hydroproject in 2010. The government of Arunachal Pradesh State awarded the project concession to KSK earlier that year, rather than to India-government-owned developer NHPC Ltd. NHPC had performed a detailed project report on then 2,000-MW Subansiri Upper and had expected to develop the project.

After the meeting with KSK at Institute Hydroproject headquarters in Moscow, the Russian firm said project capacity was reduced to 1,800 MW based on its financial analysis, which confirmed that to be the optimal capacity for minimal electricity rates.

Institute Hydroproject said KSK also agreed to its proposal for unique shaft spillways that are to provide greater safety during flooding. It said the spillways are designed to activate automatically under higher than normal water levels even when there is a power outage at the project site. Similar spillways were first built at 1,000-MW Tehri Dam, part of the three-plant 2,400-MW Tehri hydro complex. 

Institute Hydroproject said its specialists presented hydrodynamic research results intended to ensure safety of people living in the Daporijo project worker settlement at the dam toe. The Russian firm said it also plans to perform hydraulic model studies of the spillway operation modes at the scientific design complex ofits parent utility RusHydro. 

Subansiri Upper is to include a 237-meter-tall roller-compacted-concrete dam, powerhouse with six 300-MW turbine-generators, two shaft spillways with funnel crest overflow of total discharge capacity of 3,600 cubic meters per second, bank spillway chutes with discharge capacity of 7,000 cms with a flow jet to the river channel. Design of the project is scheduled to be completed in February 2012 for submission to the India government.