Nuclear power has returned to Japan's energy mix for the first time in two months, hours before a parliamentary investigative commission blamed the government's cosy relations with the industry for the meltdowns that prompted the mass shutdown of the nation's reactors.
Though the report echoes other investigations into last year's disaster at the Fukushima Dai-ichi plant, it could fuel complaints that Japan is trying to restart nuclear reactors without doing enough to avoid a repeat.
The resumption of operations at a reactor in Ohi, in western Japan, already had been hotly contested.
Government officials and the utility that runs the Ohi plant announced last month that the No 3 reactor had passed stringent safety checks and needed to be brought back online to ward off blackouts as Japan enters its high-demand summer months. The government hopes to see the restart of more of Japan's 50 working reactors as soon as possible.
"We have finally taken this first step," said Hideki Toyomatsu, vice president of Kansai Electric Power, which operates the plant and hopes to restart another reactor there in the next few weeks. "But it is just a first step."
The reactor is the first to be restarted since last year's devastating tsunami inundated the Fukushima plant, setting off meltdowns in three reactors in the world's worst nuclear crisis since Chernobyl in 1986.
All of Japan's reactors were gradually taken off-line for maintenance or safety checks, and in early May the last reactor shut down, leaving the country without nuclear-generated electricity for the first time since 1970.
The report said the Fukushima disaster was "man-made" because it should have been foreseen and avoided. It said the response "betrayed the nation's right to be safe from nuclear accidents", and was the result of collusion between the government, regulators and the utility itself that allowed lax preparation and precautions.
The 10-member panel, appointed by parliament in December, interviewed 1,167 people in hearings exceeding 900 hours. Members also inspected Fukushima Dai-ichi, the neighbouring and less-damaged Dai-ni plant, as well as two other plants in nearby prefectures.
Its bulky final report urged parliament to monitor a new regulatory agency and supervise reforms in the crisis management system. It also urged the government to set clear disclosure rules about its relationship with nuclear operators, construct a cross-monitoring system and overhaul laws governing nuclear energy "to meet global standards of safety, public health and welfare".