India and Russia signed a crucial contract on Monday to kick start the deal on the construction of a nuclear power plant at Kudankulam in Tamil Nadu. Under the contract, signed by the Managing Director of Nuclear Power Corporation of India, Mr. Y.S.R. Prasad, and the General Director of Russia's 'Atmostroiexport', Russia will prepare the detailed project report (DPR) to initiate work on designing and implementing the deal, Indian Embassy sources told.