Major Category
Physical/Radiation
Synonyms
Brevium; Uranium X2; UX2; [Merck Index # 7883]
Description
Shiny, silvery, malleable metal; All isotopes are radioactive; Pa-231 decays by alpha emission to Actinium-227; [Merck Index # 7883]
Sources/Uses
Used in scientific research with no commercial uses; It is present in uranium ores at a concentration of 1 part proactinium per 3 million parts uranium. Of the 20 known isotopes, 3 are naturally occurring: Pa-231, Pa-234, and Pa-234m with half lives of 33,000 years, 6.7 hours, and 1.2 minutes, respectively. [Argonne]
Comments
Pa-231 decays to Actinium-227 by emitting an alpha particle. Actinium-227 and its decay products account for more than 80% of the inhalation hazard associated with exposure to Pa-231. [Argonne]
Most Important Radionuclide: Pa-231
Source: Uranium ores;
Half-Life: 33,000 years
Specific Activity: 0.048 Ci/g
Decay Mode: Alpha
GI Absorption: 0.05%
Lung Clearance Half-Time: Years for oxides and hydroxides; Weeks for all other compounds;
Internal Toxicity: Very High
Annual Limit on Intake: 0.000002 mCi
Average Radiation Energy (MeV): Alpha 5.0; Beta 0.065; Gamma 0.048 [Argonne]
[See Glossary for references.] See "Radiation, ionizing."
Half Life
Biological half life: 50 years (skeleton); 10 days (liver); 10 days to 60 days (kidneys); [ANL Radiological Fact Sheets]
Other Information
No other related information on this agent was found.