In addition to the danger of explosives damaging the reactors, plant managers and technicians must have unfettered access to the plants to ensure they operate safely, nuclear experts warned.
Pharmacies in some Eastern European and Scandinavian countries reported a surge in demand for iodine tablets, which can be used to protect children from radiation exposure.
The initial explosion killed two plant workers, and 28 others died within the next three months.
Twenty-five years later, an earthquake and tsunami triggered a meltdown at the Fukushima nuclear power plant in Japan, forcing the evacuation of more than 100,000 people.
Together the reactors generate about half of the country’s electricity.
In Denmark, Sweden and Finland sales of iodine tablets have increased sharply.