While the Sredmash engineers were at work on the Sarcophagus, a scientific task force from the Kurchatov Institute began trying to unravel the mystery of what had happened to the 180 tonnes of nuclear fuel they believed still lay somewhere within its rising walls. At first, the scientists had believed that most of the uranium had been blown out of the reactor vessel by the explosion and must be scattered inside what remained of the machine hall. But radiation detectors lowered into the ruins by helicopter revealed no evidence of it there.
