An RHS is classified according to the concentration of long-lived radionuclides and their shorter-lived precursors. The class of an RHS is determined using Table 1 in §C of this regulation or Table 2 in §D of this regulation, as applicable. Classification Determined by Long-Lived Radionuclides. If the RHS contains only radionuclides listed in Table 1, classification is determined as follows: If the concentration does not exceed 0.1 times the value in Table 1, the RHS is Class A; If the concentration exceeds 0.1 times the value in Table 1, and does not exceed the value in Table 1, the RHS is Class C; If the concentration exceeds the value in Table 1, the RHS is greater than Class C and is not generally acceptable for near-surface disposal. For RHS containing mixtures of radionuclides listed in Table 1, the total concentration is determined by the sum of fractions rule described in §G of this regulation. Table 1. Classification Determined by Short-Lived Radionuclides. If the RHS does not contain any of the radionuclides listed in Table 1, classification is determined based on the concentrations shown in Table 2, as follows: If the concentration does not exceed the value in Column 1, the RHS is Class A; If the concentration exceeds the value in Column 1, but does not exceed the value in Column 2, the RHS is Class B; If the concentration exceeds the value in Column 2, but does not exceed the value in Column 3, the RHS is Class C; If the concentration exceeds the value in Column 3, the RHS is greater than Class C and is not generally acceptable for near-surface disposal. For RHS containing mixtures of the radionuclides listed in Table 2, the total concentration is determined by the sum of fractions rule described in §G of this regulation. Classification Determined by Both Long and Short-Lived Radionuclides. If the RHS contains a mixture of radionuclides, some of which are listed in Table 1, and some of which are listed in Table 2, classification is determined as follows: If the concentration of a radionuclide listed in Table 1 does not exceed 0.1 times the value listed in Table 1, the class is that determined by the concentration of radionuclides listed in Table 2; If the concentration of a radionuclide listed in Table 1 exceeds 0.1 times the value listed in Table 1, and does not exceed the value in Table 1, the RHS shall be Class C, if the concentration of radionuclides listed in Table 2 does not exceed the value shown in Column 3 of Table 2. Classification of RHS with Radionuclides Other Than Those Listed in Table 1 and 2. If the RHS does not contain any radionuclides listed in either Table 1 or 2, it is Class A. The Sum of the Fractions Rule for Mixtures of Radionuclides. For determining classification of RHS that contains a mixture of radionuclides, a person shall determine the sum of fractions by dividing each radionuclide's concentration by the appropriate limit and adding the resulting values. A person shall take the appropriate limits from the same column of the same table. If the sum of the fractions for the column is less than 1.0, the waste class shall be determined by that column. Determination of Concentrations in RHS. The concentration of a radionuclide may be determined by indirect methods such as use of scaling factors which relate the inferred concentration of one radionuclide to another that is measured, or radionuclide material accountability, if the Secretary finds there is reasonable assurance that the indirect methods can be correlated with actual measurements. The concentration of a radionuclide may be averaged over the volume of the RHS or weight of the RHS if the units are expressed as nanocuries per gram.