The failed missile test that ended in an explosion killing five atomic scientists last week on Russia's White Sea involved a small nuclear power source, according to a top official at the institute where they worked.
The men "tragically died while testing a new special device," Alexei Likhachev, the chief executive officer of state nuclear monopoly Rosatom, said at their funeral Monday in Sarov, a high-security city devoted to atomic research less than 400 km (250 miles) east of Moscow where the institute is based.
The part of the Russian Federal Nuclear Center that employed them is developing small-scale power sources that use "radioactive materials, including fissile and radioisotope materials" for the Defense Ministry and civilian uses, Vyacheslav Soloviev, scientific director of the institute, said in a video shown by local TV.