APPENDIX B-CONCENTRATIONS IN AIR AND WATER ABOVE NATURAL BACKGROUND-Continued [See footnotes at end of Appendix B] Vanadium (23)... Ytterbium (70). Yttrium (39)... Zinc (30).. Zirconium (40). Any single radionuclide not listed above with decay mode other than alpha emission or spontaneous fission and with radioactive half-life less than 2 hours. Any single radionuclide not listed above with decay mode other than alpha emission or spontaneous fission and with radioactive half-life greater than 2 hours. APPENDIX B-CONCENTRATIONS IN AIR AND WATER ABOVE NATURAL BACKGROUND-Continued [See footnotes at end of Appendix B] "Sub" means that values given are for submersion in a semispherical infinite cloud of airborne material. "These radon concentrations are appropriate for protection from radon-222 combined with its short-lived daughters. Alternatively, the value in Table I may be replaced by one-third (%) "working level." (A "working level" is defined as any combination of short-lived radon-222 daughters, polonium-218, lead-214, bismuth-214 and polonium-214, in one liter of air, without regard to the degree of equilibrium, that will result in the ultimate emission of 1.3x105 MeV of alpha particle energy.) The Table II value may be replaced by one-thirtieth (30) of a "working level." The limit on radon-222 concentrations in restricted areas may be based on an annual average. "For soluble mixtures of U-238, U-234 and U-235 in air chemical toxicity may be the limiting factor. If the percent by weight-enrichment) of U-235 is less than 5, the concentration value for a 40-hour workweek, Table 1, is 0.2 milligrams uranium per cubic meter of air average. For any enrichment, the product of the average concentration and time of exposure during a 40-hour workweek shall not exceed 8x10-3 SA μCi-hr/ml, where SA is the specific activity of the uranium inhaled. The concentration value for Table II is 0.007 milligrams uranium per cubic meter of air. The specific activity for natural uranium is 6.77x10-7 curies per gram U. The specific activity for other mixtures of U-238, U-235 and U-234, if not known, shall be: SA=3.6x101 curies/gram U U-depleted E>0.72 SA (0.4+0.38 E+0.0034 E) 10 where E is the percentage by weight of U-235, expressed as percent. NOTE: In any case where there is a mixture in air or water of more than one radionuclide, the limiting values for purposes of this Appendix should be determined as follows: 1. If the identity and concentration of each radionuclide in the mixture are known, the limiting values should be derived as follows: Determine, for each radionuclide in the mixture, the ratio between the quantity present in the mixture and the limit otherwise established in Appendix B for the specific radionuclide when not in a mixture. The sum of such ratios for all the radionuclides in the mixture may not exceed "1" (i.e., "unity") EXAMPLE: If radionuclides A, B, and C are present in concentrations CA, C, and Cc, and if the applicable MPC's, are MPCA. and MPC, and MPC respectively, then the concentrations shall be limited so that the following relationship exists: (CA/MPC)+(CB/MPC2)+(Cc/MPCC) ≤1 2. If either the identity or the concentration of any radionuclide in the mixture is not known, the limiting values for purposes of Appendix B shall be: a. For purposes of Table I, Col. 1-6x10-13 b. For purposes of Table I, Col. 2-4x10-7 3. If any of the conditions specified below are met, the corresponding values specified below may be used in lieu of those specified in paragraph 2 above. a. If the identity of each radionuclide in the mixture is known but the concentration of one or more of the radionuclides in the mixture is not known the concentration limit for the mixture is the limit specified in Appendix "B" for the radionuclide in the mixture having the lowest concentration limit; or b. If the identity of each radionuclide in the mixture is not known, but it is known that certain radionuclides specified in Appendix "B" are not present in the mixture, the concentration limit for the mixture is the lowest concentration limit specified in Appendix "B" for any radionuclide which is not known to be absent from the mixture; or If it is known that Sr 90, I 125, I 126, ❘ 129, I 131 ( 133, Table II only), Pb If it is known that Sr 90, I 129 ( 125, 126, I 131, Table II only), Pb 210, Ra If it is known that (I 129, Table II only), Ra 226, and Ra 228 are not present..... If it is known that alpha-emitters and Pb 210, Ac 227, Ra 228, and Pu 241 If it is known that alpha-emitters and Ac 227 are not present.. (PTμCi/ Table II 4. If a mixture of radionuclides consists of uranium and its daughters in ore dust prior to chemical separation of the uranium from the ore, the values specified below may be used for uranium and its daughters through radium-226, instead of those from paragraphs 1, 2, or 3 above. a. For purposes of Table I, Col. 1-1x10-10 μCi/ml gross alpha activity; or 5x10-11μCi/ml natural uranium or 75 micrograms per cubic meter of air natural uranium. b. For purposes of Table II, Col. 1-3x10-1μCi/ml gross alpha activity; 2×10-11μCi/ml natural uranium; or 3 micrograms per cubic meter of air natural uranium. 5. For purposes of this note, a radionuclide may be considered as not present in a mixture if (a) the ratio of the concentration of that radionuclide in the mixture (C to the concentration limit for that radionuclide specified in Table II of Appendix "B" (MPC) does not exceed 10, (i.e. C/MPC1/10) and (b) the sum of such ratios for all the radionuclides considered as not present in the mixture does not exceed 4 i.e. (C/MPC+G/MPG......+≤1⁄4). [25 FR 10914, Nov. 17, 1960, as amended at 25 FR 13953, Dec. 30, 1960; 26 FR 11046, Nov. 25, 1961; 29 FR 14435, Oct. 21, 1964; 30 FR 15801, Dec. 22, 1965; 31 FR 86, Jan. 5, 1966; 37 FR 23319, Nov. 2, 1972; 38 FR 29314, Oct. 24, 1973; 39 FR 23990, June 28, 1974; 39 FR 25463, July 11, 1974; 39 FR 27121, July 25, 1974; 40 FR 50705, Oct. 31, 1975] |