Data Sheet - Am-241

Radioactive Commodity Inventory Sheet

Alpha/gamma emitter

Alpha Energy = 5.114 to 5.545 MeV (100%)

Gamma Energies and Intensities = 0.06 MeV, 35.7% - 0.026 MeV 2.4%

Maximum Alpha Range in Air = 1.5 inches

Physical Half Life = 458 years

Biological Half Life = 50 years

Effective Half Life = 45 years


Found as components of M43A1 Chemical Agent Detector (CAD) cell, MC-1 and Troxler soil moisture/density Gauges.

M8A1 Chemical Agent Det. 6665011055623 2.5E-4 Ci Am-241

Maximum Activity per unit: 0.3 mCi per cell, 40 mCi per gauge.


AM-241 may be detected using Alpha Scintillator Radiac equipment. The source housing will shield the alpha particles from detection.

Am-241 may sometimes be detected with Geiger-Muller beta/gamma Radiac equipment.

NOTE: The Troxler and MC-1 sources are mixed with beryllium and this configuration emit neutrons which are not detectable with standard Radiac equipment.


Shielding may be required for Troxler and MC-1 instruments. Consult with the RPSO for shielding determination.


A leak test will be performed every six months for MC-1s and Troxler Gauges and annually for CAD or whenever contamination is suspected. Instruments in storage do not require annual leak testing, but must be leak tested before being returned to use.

The action level is 1 pCi. (0.05 Bq) per smear for Troxler/MC-1. or 3 dpm for CAD.

Any area found to be contaminated will be decontaminated and resurveyed to below removable contamination levels.


Millicurie quantities of Am-241 present an external exposure hazard. Neutron sensitive TLDs or Film Badges are required for use of the Troxler or MC-1 gauge, and when working in their storage area.


ALI is 6E-3 µCi.

Bioassay is only required in the event of a potential intake of 0.0006 µCi. Due to the aging of the CAD systems. Leaking Am-241 sources may become more common


45% of intake is transferred to the bone surface and 45% is transferred to the kidneys. The rest is assumed to be excreted.


Call DSN 314.370.6284 or send email