Neptunium, Radioactive

Radiation Limits / Potential

DECAY PATHWAY: Neptunium-237, half-life 2,144,000 years, decays via alpha emission, 4.959 MeV, to protactinium-233, half-life 26.967 days. Protactinium-233 decays via beta emission, 0.571 MeV, to uranium-233, half-life 159,200 years.
DECAY PATHWAY: Neptunium-239, half-life 2.3565 days, decays via beta(-) emission, 0.722 MeV, to plutonium-239, half-life 24,110 years. Plutonium-239 decays via alpha emission, 5.245 MeV, to uranium-235, half-life 703,800,000 years.
Half-life = 2.14X10+6 years /Neptunium-237/
Half-life = 2.355 days /Neptunium-239/
Specific Activity (Ci/g): neptunium-235 1,400; neptunium-236 0.014; neptunium-237 0.00071.
ALI values have been established for individual radionuclides and are presented in Table 1 in Appendix B to PART 20.1001-20.2401. The ALI values for inhalation, presented in Column 2 in Table 1, correspond to a committed effective dose equivalent of 5 rems (0.05 Sv) or a committed dose equivalent of 50 rems (0.5 Sv) to any individual organ or tissue, whichever is more limiting. If the ALI value presented in Table 1 is limited by the 50-rem committed dose equivalent, the controlling organ is listed directly below the ALI value, and the stochastic ALI value based on the 5-rem committed effective dose equivalent is listed ... directly below the organ name. If a stochastic ALI is listed ..., that value should be used to calculate the committed effective dose equivalent.
OCCUPATIONAL VALUES FOR NEPTUNIUM RADIONUCLIDES (All compounds Class W)
RADIONUCLIDE ORAL Ingestion ALI (uCi) INHALATION ALI (uCi) INHALATION DAC (uCi/mL)
Neptunium-232 1E+5 2E+3 (Bone Surf) 5E+2 7E-7
Neptunium-233 8E+5 3E+6 1E-3
Neptunium-234 2E+3 3E+3 1E-6
Neptunium-235 2E+4 (lower large intestine (LLI) wall) 2E+4 8E+2 (Bone Surf) 1E+3 3E-7
Neptunium-236 (1.15E+5 Y) 3E+0 (Bone Surf) 6E+0 2E-2 (Bone Surf) 5E-5 9E-12
Neptunium-236m (22.5 hr) 3E+3 (Bone Surf) 4E+3 3E+1 (Bone Surf) 7E+1 1E-8
Neptunium-237 5E-1 (Bone Surf) 1E+0 4E-3 (Bone Surf) (1E-2) 2E-12
Neptunium-238 1E+3 6E+1 (Bone Surf) 2E+2 3E-8
Neptunium-239 2E+3 (LLI wall) 2E+3 2E+3 9E-7
Neptunium-240 2E+4 8E+4 3E-5
EFFLUENT CONCENTRATIONS ESTABLISHED BY THE NRC FOR SOME NEPTUNIUM COMPOUNDS
RADIONUCLIDE EFFLUENT CONCENTRATIONS: Air (uCi/mL) EFFLUENT CONCENTRATIONS: Water (uCi/mL)
Neptunium-232 6E-9 2E-3
Neptunium-233 4E-6 1E-2
Neptunium-234 4E-9 3E-5
Neptunium-235 2E-9 3E-4
Neptunium-236 (1.15E+5 y) 8E-14 9E-8
Neptunium-236m (22.5 hr) 1E-10 5E-5
Neptunium-237 1E-14 2E-8
Neptunium-238 2E-10 2E-5
Neptunium-239 3E-9 2E-5
Neptunium-240 1E-7 3E-4
QUANTITIES OF NRC LICENSED MATERIAL REQUIRING LABELING
RADIONUCLIDE QUANTITY (uCi)
Neptunium-232 1
Neptunium-233 1,000
Neptunium-234 100
Neptunium-235 100
Neptunium-236 (1.15x10+5 y) 0.001
Neptunium-236 (22.5 hr) 1
Neptunium-237 0.001
Neptunium-238 10
Neptunium-239 100
Neptunium-240 1,000
Find more information on this substance at: PubChem, PubMed