About once a month, the same group of two dozen government officials, company executives and professors file into a bland white and beige conference room at the Ministry of Economy, Trade and Industry to plot Japan's long-term energy future.

Each has a printed agenda, a tablet computer and carton of green tea laid out neatly before them, and politely flips over a rectangular name card to request a turn to speak.

But beneath the rigid formality, there’s an increasingly divisive debate: What is the role of nuclear energy a decade after the Fukushima disaster?