That year, India and Canada signed an agreement for the construction of a natural uranium, heavy water-moderated National Research Experimental (NRX) reactor in Trombay. Bhabha's personal friendship with WB Lewis, who headed the Canadian Atomic Energy Agency at the time, proved useful to securing the deal. The reactor, named the Canada India Reactor Utility Service (CIRUS), went critical on 10 July 1960. At forty megawatts, it was the highest-output reactor in Asia at the time, and India's first plutonium source. CIRUS also served as the prototype of the successful Canada Deuterium Uranium (CANDU) reactor type. The reactor's low burn produced a large amount of weapons-grade plutonium, some of which was used in India's 1974 peaceful nuclear explosion.