Uncertainties hang over Japan's energy policy 40 years after the global panic over oil supplies shocked the nation and prodded it to diversify into nuclear power. This reliance on nuclear power, which had expanded since 1973, came to a halt following the March 2011 triple meltdowns at Tokyo Electric Power Co.'s Fukushima No. 1 nuclear power plant. The government has yet to set a new direction.

While dismissing the idea of nuclear power phaseout as unrealistic and "irresponsible," Prime Minister Shinzo Abe has said his administration will try to "reduce as much as possible" Japan's reliance on nuclear power.

But little progress has been made toward this goal and the prime minister appears to consider nuclear energy to be a key part of his administration's economic growth strategy.