By now, nine years after the meltdown at the Fukushima No. 1 nuclear power plant on March 11, there have been many books and documentaries about the disaster. Setsuro Wakamatsu's "Fukushima 50," however, is the first film dramatization to focus on front-line workers whose labors prevented a far greater catastrophe.

Based on a non-fiction book by Ryusho Kadota that compiled more than 90 interviews with everyone from plant rank-and-filers to former Prime Minister Naoto Kan, the story has life-or-death drama, with workers struggling to open vents as their allotted minutes in radiation hot zones tick by.

So why did it take so long to bring Kadota's 2012 book to the big screen? One reason may be scale: The production team re-created the sprawling Fukushima No. 1 plant site and, with a large cast and CG effects, the chaos swirling around it.