It is hard to imagine entering a rabbit hole under the charred Chernobyl No. 4 reactor. Alexander Kupny did just that many times. He showed me photos he took during his expeditions underground into the reactor cavern. He would go with a friend on the sly without official permission. The explosion that occurred on April 26, 1986, thirty seconds after the reactor was shut down for an experimental safety test, blew off the building's 4 million pound concrete roof as well as the upper walls and part of the machine room. The fire generated by the eruption burned at greater than two thousand degrees Celsius. The tremendous heat melted iron, steel, cement, machinery, graphite, uranium, and plutonium, turning it all into a running lava that poured down through the blown floors of the reactor complex. The lava eventually cooled into stalactites, black, sparkling, and impenetrable. One stalactite is called the ‘elephant's leg’ for its thickness, gray shade, and deep furrows. In the months following the accident, scientists estimated (because it was too hot to measure directly) that the elephant's leg emitted ten thousand roentgens an hour. To translate that measurement biologically, ten thousand roentgens means thirty seconds spent near the leg would cause dizziness and nausea for the rest of the week. Two minutes and cells would hemorrhage, four minutes would lead to diarrhea and fever, while five minutes would deliver to most people a fatal dose.

In 1989, Kupny worked as a health physics technician at Reactor No. 3, which was paired with Reactor No. 4 and still functioned after the accident. He had volunteered to go to Chernobyl, like tens of thousands of Soviet citizens in the late 1980s, because he believed it was his patriotic duty to help out after the catastrophe.4 He was also intrigued professionally. The smoking Chernobyl plant had radiation levels like nowhere else on earth. Chernobyl, Kupny said, ‘was the Klondike of radiation fields.’ He approached the blown reactor not with justifiable dread but with a sense of opportunity. Inside the ruined reactor, he had a chance to measure radiation at levels few others could experience. ‘I didn't look at the Chernobyl sarcophagus with fear. I saw it as a phenomenon. You can't study something you fear.’