Victoreen Models 247 A and 247B Ion Chambers (ca. 1945-1955)
|The Model 247 was
designed as a more rugged, waterproof version of Victoreen’s first ion
chamber survey meter, the “little black suitcase.”
It was developed and produced in large quantities during World War
II as part of the highly secret Operation Peppermint.
Operation Peppermint’s mission was to counter the potential use
of radioactive materials by the Germans against the Allied invasion of
Model 247A (above and to right)
The thick case of the Model 247A meant that it was only responsive to gamma rays. It (and the Model 247C) employed four ranges: 0-2.5 mR/h, 0 – 25 mR/h, 0 – 250 mR/h, and 0 – 2500 mR/h. The ranges of the Model 247B and 247D were 0- 50 mR/h, 0-500 mR/h, 0-5 R/h and 0- 50 R/h. The difference between the Models 247A and B on one hand, and the Models 247C and D on the other, was that the latter two employed a removable cover over the ion chamber. Removing the cover improved the response to x-rays.
Model 247B (above and to right)
|The Model Series
Index produced by the Victoreen Corporation assigns a date of July 1943 to
the Model 247 and the Operations Crossroads report by Henry Paul indicates
the this instrument used at least as late as 1946 during the atomic tests
in the Pacific. The earliest
published reference I have for the Model 247A, the version pictured here,
is the October 1949 issue of Nucleonics. The radiological control program
for the state of
The photograph to the upper right shows what the original Model 247 looked like (not in ORAU collection).
The image to the right, taken from the U.S. Air Force film "Radiological Safety on Operation Sandstone" (ca 1948), shows a training session in the use of the 247A. The entire film can be viewed at the Internet Archives (https://archive.org/details/73862RadiologicalSafety).
"Radiological Safety at Operation Crossroads," also made available by Internet Archives, has brief clips of the original Model 247 in use.
Donated courtesy of Riasp Medora, Rod Nelson, and Glen Newtown
Detector: air filled ion chamber (56 cubic inches)
Size: ca 5 1/2" x 10 1/2" x 13"
Weight: ca. 12 lbs
Batteries: one 22.5 volt, one 45 volt, one 300 volt
Controls: Battery on/off/check switch, Range switch, Zero adjust
Case: cast aluminum 1/8"
Prices: Model A $395, Model B $385, Model C $425, Model D $415 (in 1953-1954 GE Catalog)
Lapp, R., Survey of
Nucleonics Instrumentation Industry, Nucleonics May 1949, p. 100.
report by Henry Paul,
Atomic Energy Commission Radiation Instrument Catalog, Catalog No. 2, Part 2, page date July 1, 1950; page SIC-9B;
Atomic Energy Commission Radiation Instrument Catalog, Catalog No. 3, Part 2, July 1, 1952; page SIC-9B;
Campbell, D.C. Radiological Defense, Vol. IV, Armed Forces Special Weapons Project, 1950.
Copyright 1999, Oak Ridge Associated Universities