Restarted Japanese nuclear plant reaches critical level A crowd estimated at 150,000-strong protested against the restart outside the official residence of Yoshihiko Noda, the Japanese prime minister, on Friday evening, while some 100 demonstrators used cars in an attempt to block the road to the Oi plant over the weekend. On Monday, electricity savings targets set by the government went into effect across the country. Households and businesses are being asked to cut their energy consumption by as much as 15 percent until September 7. Utilities are still warning, however, that they may have to impose rolling blackouts in areas where demand is outstripping supply. One of the most critical areas is the Kansai area, centered on Japan's second city of Osaka, and partly supplied by the Oi nuclear facility. The Oi reactor is the first of Japan's 51 commercial reactors to go back on-line, although the No. 4 reactor at the plant is also scheduled to go back into operation before the end of July. On Sunday, emergency teams at the crippled Fukushima plant managed to restore the cooling system for the spent fuel pool, where the temperature of the water had risen nearly 10 degrees after the power unit failed. Another fault in early June had a similar effect on the pool, which contains 1,353 fuel assemblies that would release massive amounts of radiation if exposed to the air.