Radium Plaque (ca. 1920s to 1940s)

*Note: This is not in the ORAU Collection, but is shown for informational purposes.

The most common radium plaques were square but circular and oval ones were also available. The plaques might be covered with a thin layer (e.g., 0.1 mm) of monel metal, lead, silver or other filtration.

Radium Plaque (ca. 1920s to 1940s)
Radium Plaque

Plaque activities were expressed as follows:

  • Double strength - 10.0 mg Ra-226/cm2
  • Full strength - 5.0 mg Ra-226/cm2
  • Half strength - 2.5 mg Ra-226/cm2
  • Quarter strength - 1.25 mg Ra-226/cm2

Typical sizes were as follows:

  • Double strength - 1 cm2, 2 cm2
  • Full strength - 1 cm2, 2 cm2, 4 cm2
  • Half strength - 2 cm2, 4 cm2, 8 cm2
Radium Plaque
Radium Plaque

The most common type of plaque would be the 4 cm2 (2 cm x 2 cm) half strength version, i.e., 10 mg Ra-226.

Radium plaques might be made of monel metal, enamel or brass. Often manipulated with a handle/applicator similar to that in the following images.


  • Radium Chemical Company catalog. Radium Radon. No date. ca. 1940s, 1950s.
  • Union Miniere catalog. Radium, Radon, Radium D. No date.