I wouldn't say they were direct. That number is based on a comparison with a 1916 tsunami and earthquake death toll, and with around one of those thirty-four being under sixty that seems hard to calculate exactly.
All of this needs to be put in the context of a natural disaster that killed >15,000 people and leveled hundreds of thousands of buildings. The power plant really shouldn't lead the story here.
The tsunami killed two workers, but the nuclear incident as such didn't kill a single person.