The Russian state nuclear agency, Rosatom, said the experts had been testing a nuclear-powered engine. But it gave no further technical details. "These new systems have their origin in Soviet times - they've been taken off the shelves and given new investment." The five nuclear engineers who died were "elite" experts and "heroes" who knew of the risks and had conducted previous tests in "extraordinarily tough conditions", senior Rosatom official Valentin Kostyukov said. Soon after the blast the Severodvinsk administration reported a 40-minute spike in radiation in the city, and news of that prompted locals to buy up stocks of...