For more than 30 years, Kodak Park was home to a little-known underground labyrinth containing a small nuclear research reactor, one of the few of its kind in the world.

Still, the reactor was locked down, remotely surveilled and tightly regulated — mainly because it contained 3½ pounds of highly enriched uranium.

Company spokesman Christopher Veronda said he could find no record that Kodak ever made a public announcement of the facility. He also wasn’t sure whether the company had ever notified local police, fire or hazardous-materials officials.

The Willis (formerly Sears) Tower in Chicago, completed in 1973, has long been rumored to have a small reactor in the 3rd subbasement.

Declassified documents cited in the Bulletin of Atomic Scientists highlighted yet another incident showing that the government was aware of the far-reaching effects of fallout. In the 1950s, film manufacturers at Eastman Kodak in Rochester, New York wondered why their film was fogging as though it had been exposed to radiation. Scientists linked the fogged film to nuclear tests in Nevada. The government warned Kodak about expected areas of heavy fallout so they could protect unexposed film. People living downwind never received the same courtesy.