The Philadelphia Incident

On September 2, 1944, three men entered the transfer room of the liquid thermal diffusion semi-works at the Philadelphia Navy Yard to repair a clogged tube. The tube they were working on consisted of two concentric pipes with liquid uranium hexafluoride circulating in the space between them; the innermost pipe contained high-pressure steam.

These men, all from different backgrounds and each representing a different facet of the complex Manhattan Engineer District, had one thing in common: they had all volunteered to work in a dangerous environment on a process that only recently had moved from the laboratory experimental stage to a pilot plant operation.

Peter N. Bragg Jr., a chemical engineer from Arkansas, was hired in June by the Navy Research Lab; Douglas P. Meigs was an employee of the H. K. Ferguson Company of Cleveland, OH, the prime contractor for the thermal diffusion project; and, Arnold Kramish, a physicist by education and a member of the Special Engineer Detachment (SED), was on loan from Oak Ridge, TN.

Kneeling on the floor with a Bunsen burner, Bragg and Meigs worked to free the clogged tube. Without warning, at 1:20 PM, there was a terrific explosion. As the tube shattered, the liquid uranium hexafluoride combined with the escaping steam and showered the two engineers with hydrofluoric acid, one of the most corrosive agents known.

Within minutes, both Peter Bragg and Douglas Meigs, with 3rd degree burns over their entire bodies, were dead and Arnold Kramish, also burned, was near death. Thus began one of the most extraordinary events in the history of the Manhattan Project.

Due to the extreme secrecy surrounding the Manhattan Project in general and the experimental facility at the Philadelphia Navy Yard in particular, an immediate veil was drawn down over the incident by the highest authority available: General Leslie Groves.

Due to the extreme secrecy surrounding the incident, even the Philadelphia coroner was not made aware of the actual causes of death. It was not until many years later that the true facts began to emerge. However, it was too late for the parents of Peter Bragg, who both died never knowing of how their son had died.