While most of the report focuses on continued trafficking in nuclear material and the need to lock down vulnerable nuclear sites, it also confirms what nuclear-power watchdog groups in the US have been saying for months – that Fukushima demonstrated an acute vulnerability that could be exploited at US reactor sites.
"Terrorists will most likely try to damage a reactor’s support and water-supply systems as well as its control and protection system to cause a heat explosion of the reactor with subsequent demolition of the reactor and the building in which it is located," the Harvard study notes.
Pools of circulating water that cool spent fuel could be an attractive a target, the report adds. At the Fukushima Daiichi plant, the spent-fuel pool belonging to its No. 4 reactor lost power to its cooling system, resulting in the water boiling off and a spent-fuel fire that released radiation directly into the atmosphere.
At least 28 reactors in the US have designs similar to the Fukushima plant, where spent-fuel pools are suspended near the ceiling of the reactor building. Such pools, when loaded with spent fuel, are safe as long as their cooling systems are working.
But US spent-fuel pools tend to be far more heavily loaded than those in Japan. Today, some 65,000 metric tons of spent fuel is stored at reactor sites around the country, 75 percent of it in US spent-fuel pools, according to data from the Nuclear Energy Institute cited in a recent report by the non-partisan Institute for Policy Studies.
Some 30 million such rods are stored in spent-fuel pools at 51 sites around the country that "contain some of the largest concentrations of radioactivity on the planet," that study said.