Operation Peppermint

In response, the Metallurgical Laboratory in Chicago and the Victoreen Instrument Company in Cleveland developed portable radiation detection devices suitable for use in the field.

[1][2] Consideration was given to issuing a public warning of the danger of a German nuclear attack on the United States, but the director of the Manhattan Project, Brigadier General Leslie R. Groves, Jr., considered the likelihood of this to be sufficiently remote that he rejected the notion of taking so drastic a step.

[3] A subcommittee of the S-1 Executive Committee, chaired by James B. Conant, and consisting of himself, Arthur Compton and Harold Urey, was appointed to look into the issue, and it similarly assessed the danger as low, but still sufficient to warrant taking some precautions.

A program was initiated by the Metallurgical Laboratory in Chicago and the Victoreen Instrument Company in Cleveland to develop radiation detection devices suitable for use in the field.

[4][2][5] As the date for the Normandy landings (codenamed Operation Overlord) drew near in early 1944, Groves considered that risk was sufficient to send an officer to brief the Supreme Commander General Dwight D. Eisenhower of the possible use of radioactive poisons, particularly plutonium and fission products that might be created in their nuclear reactors.

[7] Further briefings were given to Admiral Harold Stark, and Lieutenant Generals Carl Spaatz and John C. H. Lee, and Eisenhower also wrote to Lieutenant General Hastings Ismay, the chief of staff of the Prime Minister of the United Kingdom, Winston Churchill to inform the British Chiefs of Staff, but no British or American commanders actually participating in Operation Overlord were informed.

Survey teams from the Manhattan Project used the equipment to assess the fallout from the Trinity nuclear test,[12] the bombing of Hiroshima and Nagasaki,[13] and Operation Crossroads, during which 10,000 film badges were used.