Between 5 and 11 PM radar targets returned to the Oak Ridge area.  Fighters were scrambled. They saw nothing.

However, at 7 PM, during this period of radar sightings, graphic records of Geiger counter detections in the restricted area of Oak Ridge indicated an abnormal increase in alpha and gamma radiation that could not be attributed to a known source.  Apparently this was “too much” for the officials in charge of Oak Ridge security.  They held a two day meeting to discuss the “operational difficulties” of the early warning radar of the Air Defense Command at Knoxville.  AFI was asked to investigate the situation and to set up a separate radar set for comparison. (McDonald list)

The suggestion that some radar targets might be the result of ionization of the air by nuclear radiation must have been on the mind of Mr. Gray, SAC Knoxville, because on December 4 he called FBI headquarters and discussed the speculation that releases of radioactive material could have caused the anomalous radar targets observed.  The next day Mr. Hoover sent an urgent teletype to SAC Knoxville: “Arrangements should be made to obtain all facts concerning possible radar  jamming by ionization of particles in the atmosphere.  Conduct appropriate investigation to determine whether incident occurring northeast of Oliver Springs, Tennessee, could have had any connection with alleged radar jamming.”    Unfortunately any information that might have been available on the “Oliver Springs” case has not been released.  Nor is there any response to Hoover’s teletype message.

On December 5 and 6 there was a discussion of the technical aspects of the radar sightings with ATIC and intelligence officials.  They concluded that the targets were probably “radar angels” which are reflections of objects on the ground which are observed only because of a temperature inversion which bends the radar radiation downward.  On the other hand, that did not mean that there were no flying saucers around.