Major Category
Physical/Radiation
Description
A man-made, radioactive metal with a melting point of 577 degrees C; [Merck Index # 6471]
Sources/Uses
Neptunium is usually produced in nuclear reactors as a byproduct of plutonium production. There are no commercial uses, but Np-237 has been used in instruments to detect neutrons. Of the 17 known isotopes, Np-237 is the most prevalent at DOE sites such as Hanford. [Argonne]
Comments
Neptunium is toxic after ingestion or inhalation. Some of the isotopes also have a small risk of generating significant external radiation (Np-236 and Np-237). [Argonne]
Most Important Radionuclide: Np-237
Half-Life: 2.1 million years
Effective Half-Life: 200 years
Specific Activity: 0.00071 Ci/g
Decay Mode: Alpha
GI Absorption: 0.05%
Lung Clearance Half-Time: Weeks (10-100 days) for all compounds;
Critical Organ: Bone
Internal Toxicity: Very High
Annual Limit on Intake: 0.000004 mCi
Average Radiation Energy (MeV): Alpha 4.8; Beta 0.070; Gamma 0.035 [Argonne]
[See Glossary for references.] See "Radiation, ionizing."
Half Life
Biological half-life: 20 years (liver) and 50 years (bone); [ANL Radiological Fact Sheets]
Other Information
No other related information on this agent was found.