A mishap by a Russian contractor has triggered concerns of radiation risks in East Siberia’s Irkutsk region after its expedition truck lost a capsule containing Caesium-137 on its way to a well that was scheduled for a logging operation.

Oilfield service contractor TNG Group, headquartered in Russia’s Tatarstan republic, acknowledged the incident and said it was the first of its kind in the company’s 70 years of operations.