Actinium, Radioactive

Atomic number 89; valence: 3; no stable nuclides; known isotopes (mass numbers): 209-233; naturally occurring isotopes: 227, 228; homologous with lanthanum; more basic than lanthanum; strong electropositive element; forms insoluble salts, e.g., carbonate, oxalate, phosphate, etc., just as the lanthanides; rapidly oxidizes to AcO3 in moist air

/Actinium-225/ Atomic weight = 225.02322; half-life = 10.0 days; alpha emission, 5.935 MeV

/Actinium-227/ Atomic weight = 227.027747; half-life = 21.77 years; negative beta emission, 0.045 MeV; alpha emission, 5.043 MeV

/Actinium-228/ Atomic weight = 228.031014; half-life = 6.15 hours; negative beta emission, 2.127 MeV

DECAY PATHWAY: Actinium-225, half-life 10.0 days, decays via alpha emission, 5.935 MeV, to francium-221, half-life 4.9 minutes. Francium-221 decays via alpha emission, 6.458 MeV, to astatine-227, half-life 32.2 minutes; decays via beta emission, 0.312 MeV, to radium-221, half-life 28 seconds.

DECAY PATHWAY: Actinium-227, half-life 21.77 years, decays via beta emission (98.62%), 0.045 MeV, to thorium-227, half-life 7,340 years. Thorium-227 decays via alpha emission, 6.146 MeV, to radium-223, half-life 11.425 days. Actinium-227 decays via alpha emission (1.38%), 5.043 MeV, to francium-223, half-life 22.00 minutes. Francium-223 decays via beta emission, 1.149 MeV, to radium-223.

DECAY PATHWAY: Actinium-228, half-life 6.15 hours, decays via beta emission, 2.127 MeV, to thorium-228, half-life 1.9116 years.

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 in parentheses, that value should be used to calculate the committed effective dose equivalent.

OCCUPATIONAL VALUES FOR ACTINIUM-224

CLASS	ORAL Ingestion ALI (uCi)	INHALATION ALI uCi)	INHALATION DAC (uCi/mL)
D, all cds except for W & Y	2E+3 LLI wall 2E+3	3E+1 Bone surf 4E+1	1E-8
W, halides and nitrates	-	5E+1	2E-8
Y, oxides and hydroxides	-	5E+1	2E-8

OCCUPATIONAL VALUES FOR ACTINIUM-225

CLASS	ORAL Ingestion ALI (uCi)	INHALATION ALI uCi)	INHALATION DAC (uCi/mL)
D, all cds except for W & Y	5E+1 LLI wall 5E+1	3E-1 Bone surf 5E-1	1E-10
W, halides and nitrates	-	6E-1	3E-10
Y, oxides and hydroxides	-	6E-1	3E-10

OCCUPATIONAL VALUES FOR ACTINIUM-226

CLASS	ORAL Ingestion ALI (uCi)	INHALATION ALI uCi)	INHALATION DAC (uCi/mL)
D, all cds except for W & Y	1E+2 LLI wall 1E+2	3E+0 Bone surf 4E+0	1E-9
W, halides and nitrates	-	5E+0	2E-9
Y, oxides and hydroxides	-	5E+0	2E-9

OCCUPATIONAL VALUES FOR ACTINIUM-227

CLASS	ORAL Ingestion ALI (uCi)	INHALATION ALI uCi)	INHALATION DAC (uCi/mL)
D, all cds except for W & Y	2E-1 (Bone surf) 4E-1	4E-4 (Bone surf) 8E-4	2E-13
W, halides and nitrates	-	2E-3 (Bone surf) 3E-3	7E-13
Y, oxides and hydroxides	-	4E-3	2E-12

OCCUPATIONAL VALUES FOR ACTINIUM-228

CLASS	ORAL Ingestion ALI (uCi)	INHALATION ALI uCi)	INHALATION DAC (uCi/mL)
D, all cds except for W & Y	3E+3	9E+0 (Bone surf) 2E+1	4E-9
W, halides and nitrates	-	4E+1(Bone surf) 6E+1	2E-8
Y, oxides and hydroxides	-	4E+1	2E-8

EFFLUENT CONCENTRATIONS ESTABLISHED BY THE NRC FOR SOME ACTINIUM COMPOUNDS

RADIONUCLIDE	CLASS	AIR (uCi/mL)	WATER (uCi/mL)
Actinium-224	D, all compounds except forthose given for W and Y	5E-11	3E-5
	W, halides and nitrates	7E-113	-
	Y, oxides and hydroxides	6E-11	-
Actinium-225	D	7E-13	7E-7
	W	9E-13	-
	Y	9E-13	-
Actinium-226	D	5E-12	2E-6
	W	7E-12	-
	Y	6E-12	-
Actinium-227	D	1E-15	5E-9
	W	4E-15	-
	Y	6E-15	-
Actinium-228	D	2E-11	3E-5
	W	8E-11	-
	Y	6E-11	-

QUANTITIES OF NRC LICENSED MATERIAL REQUIRING LABELING

RADIONUCLIDE	QUANTITY (uCi)
Actinium-224	1
Actinium-225	0.01
Actinium-226	0.1
Actinium-227	0.001
Actinium-228	1