Science reports:

When the lights went out at Chernobyl Nuclear Power Plant on 9 March, the Russian soldiers holding Ukrainian workers at gunpoint became the least of Anatolii Nosovskyi’s worries. More urgent was the possibility of a radiation accident at the decommissioned plant. If the plant’s emergency generators ran out of fuel, the ventilators that keep explosive hydrogen gas from building up inside a spent nuclear fuel repository would quit working, says Nosovskyi, director of the Institute for Safety Problems of Nuclear Power Plants (ISPNPP) in Kyiv. So would sensors and automated systems to suppress radioactive dust inside a concrete “sarcophagus” that holds the unsettled remains of Chernobyl’s Unit Four reactor, which melted down in the infamous 1986 accident.

Although power was restored to Chernobyl on 14 March, Nosovskyi’s worries have multiplied. In the chaos of the Russian advance, he told Science, looters raided a radiation monitoring lab in Chernobyl village—apparently making off with radioactive isotopes used to calibrate instruments and pieces of radioactive waste that could be mixed with conventional explosives to form a “dirty bomb” that would spread contamination over a wide area. ISPNPP has a separate lab in Chernobyl with even more dangerous materials: “powerful sources of gamma and neutron radiation” used to test devices, Nosovskyi says, as well as intensely radioactive samples of material leftover from the Unit Four meltdown. Nosovskyi has lost contact with the lab, he says, so “the fate of these sources is unknown to us.”

The drama at Chernobyl began on 24 February, the very first day of the invasion. At 5 a.m., as Russian troops poured across Ukraine’s border with Belarus—just 15 kilometers from Chernobyl—ISPNPP managers were ordered to evacuate most staff, who monitor the safety of the plant, provide technical support for decommissioning, and develop protocols for managing radioactive waste in the off-limits “exclusion zone” surrounding Chernobyl. Within 2 hours, 67 had cleared out; two who live in Chernobyl village stayed behind to keep an eye on the institute’s lab. “We’ve lost contact with these brave people,” says ISPNPP senior scientist Maxim Saveliev. [Continue reading…]