Vattenfall (then called "Kungliga Vattenfallsstyrelsen" or Royal Waterfall Board) was founded in 1909 as a state-owned enterprise in Sweden. From its founding until the mid-1970s, Vattenfall's business was largely restricted to Sweden, with a focus on hydroelectric power generation. Only in 1974 did the company begin to build nuclear reactors in Sweden (the Ringhals 1 and 2 reactors), eventually owning seven of Sweden's 12 reactors. In 1992, Vattenfall was reformed as the limited liability company Vattenfall AB. At the same time, the transmission grid (220 kV and 400 kV lines) was transferred to the newly formed state agency Svenska kraftnät, which also became responsible for the operation of the national power system.