## 3 Results  
NUREG/CR-1757 recommends the use of the peak of the mean dose to derive the DCGL value. According to the previous studies [2; 13; 27], the DCGL formula can be expressed as follows:  
\[\text{DCGL}=\frac{\text{Regulatory Dose Limit}}{\text{Peak of Mean Dose}} \tag{1}\]  
Table 4 shows the preliminary DCGL results derived with the assigned value for each radionuclide through probabilistic analysis (see Table 10). As presented in Table 10, the highest PRCC values were mostly due to the external gamma shielding factor, density of contaminated zone, runoff coefficient, distribution coefficients, evapotranspiration coefficient, etc. The PRCC and assigned values will be further discussed in the following chapter. The regulatory dose limit applied in this study was 0.25 mSv-year\({}^{-1}\) according to the 10 CFR Part 20, subpart E in the U.S., and 0.1 mSv-year\({}^{-1}\) according to the Nuclear Safety and Security Commission Notification No. 2016-33 in South Korea. On deriving the preliminary DCGLs for 14 target radionuclides, the radionuclide \({}^{93\text{m}}\)Nb yielded the largest DCGL value, followed by \({}^{55}\)Fe, \({}^{121}\)Sm, and \({}^{63}\)Ni. Those large DCGL values of several radionuclides were seemingly caused by their large Kd values (e.g., log Kd saturated zone = 2.93 \(\pm\) 0.48 for Nb, 3.52 \(\pm\) 0.70 for Sn, 2.82 \(\pm\) 0.65 for Ni, respectively) inducing remarkable retardation of migration along with relatively short half-life (e.g., t\({}_{1/2}\) = 2.7 years for \({}^{55}\)Fe and 16 years for \({}^{93\text{m}}\)Nb). The result of the preliminary DCGL of the Wolsong NPP site soil derived in this study was compared with other studies [13; 28; 29; 30; 31] as presented in Table 5. The authors note that the regulatory dose limit was unified to the U.S. criterion of 0.25 mSv-year\({}^{-1}\) to establish the same criterion for the comparison among various studies. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Radionuclides**} & **Regulatory Dose Limit** & **DCGL (Bq\(\cdot\)g\({}^{-1}\))** \\ \cline{2-4}  & **0.25 mSv\(\cdot\)year\({}^{-1}\)** & **0.1 mSv\(\cdot\)year\({}^{-1}\)** \\ \hline \({}^{108\text{m}}\)Ag & 2.56 \(\times\) 10\({}^{-1}\) & 1.02 \(\times\) 10\({}^{-1}\) \\ \({}^{14}\)C & 2.07 \(\times\) 10\({}^{0}\) & 8.27 \(\times\) 10\({}^{-1}\) \\ \({}^{60}\)Co & 1.73 \(\times\) 10\({}^{-1}\) & 6.90 \(\times\) 10\({}^{-2}\) \\ \({}^{134}\)Cs & 2.93 \(\times\) 10\({}^{-1}\) & 1.17 \(\times\) 10\({}^{-1}\) \\ \({}^{137}\)Cs & 6.65 \(\times\) 10\({}^{-1}\) & 2.66 \(\times\) 10\({}^{-1}\) \\ \({}^{55}\)Fe & 1.47 \(\times\) 10\({}^{3}\) & 5.87 \(\times\) 10\({}^{2}\) \\ \({}^{3}\)H & 1.88 \(\times\) 10\({}^{2}\) & 7.51 \(\times\) 10\({}^{1}\) \\ \({}^{93\text{m}}\)Nb & 5.63 \(\times\) 10\({}^{3}\) & 2.25 \(\times\) 10\({}^{3}\) \\ \({}^{94}\)Nb & 2.62 \(\times\) 10\({}^{-1}\) & 1.05 \(\times\) 10\({}^{-1}\) \\ \({}^{63}\)Ni & 5.03 \(\times\) 10\({}^{2}\) & 2.01 \(\times\) 10\({}^{2}\) \\ \({}^{125}\)Sb & 1.21 \(\times\) 10\({}^{0}\) & 4.86 \(\times\) 10\({}^{-1}\) \\ \({}^{121}\)Sm & 6.01 \(\times\) 10\({}^{2}\) & 2.41 \(\times\) 10\({}^{2}\) \\ \({}^{90}\)Sr & 8.42 \(\times\) 10\({}^{-1}\) & 3.37 \(\times\) 10\({}^{-1}\) \\ \({}^{93}\)Zr & 6.75 \(\times\) 10\({}^{1}\) & 2.70 \(\times\) 10\({}^{1}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: DCGL results for various radionuclides were calculated with two different regulatory dose limits.