323 A Table of Frequently Used Radioisotopes Only decays with the largest branching fractions are listed. For β emitters the maximum energies of the continuous β-ray spectra are given. ‘→’ denotes the decay to the subsequent element in the ta- ble. EC stands for ‘electron capture’, a (= annus, Latin) for years, h for hours, d for days, min for minutes, s for seconds, and ms for milliseconds. isotope decay half- β resp. α γ energy A Z element type life energy (MeV) (MeV) 3 β− . γ 1H 12 3a 0.0186 no 7 γ 4Be EC, 53 d – 0.48 10 β− . × 6 γ 4Be 1 5 10 a 0.56 no 14 β− γ 6C 5730 a 0.156 no 22 β+ . 11Na ,EC 2 6a 0.54 1.28 24 β− γ . 11Na , 15 0h 1.39 1.37 26 β+ . × 5 13Al ,EC 7 17 10 a 1.16 1.84 32 β− γ 14Si 172 a 0.20 no 32 β− . γ 15P 14 2d 1.71 no 37 γ 18Ar EC 35 d – no 40 β− . × 9 19K ,EC 1 28 10 a 1.33 1.46 51 γ . 24Cr EC, 27 8d – 0.325 54 γ 25Mn EC, 312 d – 0.84 55 . 26Fe EC 2 73 a – 0.006 57 γ 27Co EC, 272 d – 0.122 60 β− γ . 27Co , 5 27 a 0.32 1.17 & 1.33 66 β+ γ . 31Ga , EC, 9 4h 4.15 1.04 68 β− γ 31Ga , EC, 68 min 1.88 1.07 85 β− γ . 36Kr , 10 8a 0.67 0.52 89 β− γ 38Sr 51 d 1.49 no 90 → β− . γ 38Sr 28 7a 0.55 no 90 β− γ 39Y 64 h 2.28 no 99m γ 43Tc 6h – 0.140 C. Grupen, Introduction to Radiation Protection, Graduate Texts in Physics, DOI 10.1007/978-3-642-02586-0 © Springer-Verlag Berlin Heidelberg 2010 324 A Table of Frequently Used Radioisotopes isotope decay half- β resp. α γ energy A Z element type life energy (MeV) (MeV) 106 → β− . γ 44Ru 1 0a 0.04 no 106 β− γ 45Rh , 30 s 3.54 0.51 112 β− γ . 47Ag , 3 13 h 3.90 0.62 109 → . γ 48Cd EC 1 27 a – no 109m γ 47Ag 40 s – 0.088 113 γ 50Sn EC, 115 d – 0.392 132 β− γ 52Te , 77 h 0.22 0.23 125 γ 53I EC, 60 d – 0.035 129 β− γ . × 7 53I , 1 6 10 a 0.15 0.038 131 β− γ . 53I , 8 05 d 0.61 0.36 133 β− γ . 54Xe , 5 24 d 0.35 0.08 134 β− β+ γ . 55Cs , , 2 06 a 0.65 0.61 137 → β− 55Cs 30 a 0.51 & 1.18 0.66 137m γ . 56Ba 2 6min – 0.66 133 γ . 56Ba EC, 10 5a – 0.36 140 β− γ . 57La , 40 2h 1.34 1.60 144 → β− γ 58Ce , 285 d 0.32 0.13 144 β− γ . 59Pr , 17 5min 3.12 0.69 144 α . × 15 γ 60Nd 2 3 10 a 1.80 no 152 β∓ γ . 63Eu EC, , 13 5a 0.68 0.122 192 β− γ 77Ir EC, , 74 d 0.67 0.32 198 β− γ . 79Au , 2 7d 0.96 0.41 204 β− . γ 81Tl ,EC 3 78 a 0.76 no 207 γ . 83Bi EC, 31 6a 0.48 0.57 222 → α γ . 86Rn , 3 8d 5.48 0.51 218 → α β− . α γ 84Po , 3 1min :6.00 no 214 → β− γ . 82Pb , 26 8min 0.73 0.35 214 β− γ . 83Bi , 19 9min 1.51 0.61 226 α γ 88Ra , 1600 a 4.78 0.19 228 α γ . 90Th , 1 9a 5.42 0.24 234 α γ . × 5 92U , 2 5 10 a 4.77 0.05 A Table of Frequently Used Radioisotopes 325 isotope decay half- β resp. α γ energy A Z element type life energy (MeV) (MeV) 235 α γ . × 8 92U , 7 1 10 a 4.40 0.19 238 α γ . × 9 92U , 4 5 10 a 4.20 0.05 239 α γ 94Pu , 24 110 a 5.15 0.05 240 α γ 94Pu , 6564 a 5.16 0.05 241 α γ 95Am , 432 a 5.49 0.06 252 α γ . 98Cf , 2 6a 6.11 0.04 252 α γ 100Fm , 25 h 7.05 0.096 268 α 109Mt 70 ms 10.70 – Explanatory note The heavy α-ray-emitting radioisotopes can also decay by sponta- neous fission. Half-lives for spontaneous fission are usually rather long. More detailed information about decay modes and level dia- grams can be taken from nuclear data tables. Corresponding refer- ences are listed under ‘Further Reading’ in the section ‘Tables of Isotopes and Nuclear Data Sheets’. The most recent information on the table of isotopes can be found in the Internet under http://atom.kaeri.re.kr/ and http://isotopes.lbl.gov/education . “We will be rich! This isotope decays into gold!” c by Claus Grupen 326 B Examples of Exemption Limits for Absolute and Specific Activities There are no universal international values for exemption limits for radioactive sources and radioactive material. Different countries have defined limits based on the guidelines as recommended by the International Commission on Radiological Protection. The table be- low gives some examples which have been adopted by the new Ger- man radiation-protection ordinance in 2001. The corresponding lim- its in other countries are quite similar, although there are also some important differences in some national regulations. If several sources each with activity Ai and corresponding ex- max emption limit Ai are handled in a laboratory, the following con- dition must be fulfilled: N A i ≤ 1 . Amax i=1 i This prevents the acquisition of several sources each with an activity below the exemption limit thereby possibly circumventing the idea of the exemption limit. radioisotope exemption limit activity specific in Bq activity in Bq/g 3 9 6 1H 10 10 7 7 3 4Be 10 10 14 7 4 6C 10 10 24 5 11Na 10 10 32 5 3 15P 10 10 40 ∗ 6 2 19K 10 10 54 6 25Mn 10 10 55 6 4 26Fe 10 10 57 6 2 27Co 10 10 60 5 27Co 10 10 B Exemption Limits for Absolute and Specific Activities 327 radioisotope exemption limit activity specific in Bq activity in Bq/g 82 6 35Br 10 10 89 6 3 38Sr 10 10 90 † 4 2 38Sr 10 10 99m 7 2 43Tc 10 10 106 † 5 2 44Ru 10 10 110m 6 47Ag 10 10 109 † 6 4 48Cd 10 10 125 6 3 53I 10 10 129 5 2 53I 10 10 131 6 2 53I 10 10 134 4 55Cs 10 10 137 † 4 55Cs 10 10 133 6 2 56Ba 10 10 152 6 63Eu 10 10 197 7 2 80Hg 10 10 204 4 4 81Tl 10 10 214 6 2 82Pb 10 10 207 6 83Bi 10 10 210 4 84Po 10 10 220 † 7 4 86Rn 10 10 222 † 8 86Rn 10 10 226 † 4 88Ra 10 10 227 † 3 . 89Ac 10 0 1 232 † 4 90Th 10 10 233 4 92U 10 10 235 † 4 92U 10 10 238 † 4 92U 10 10 239 4 94Pu 10 1 240 3 94Pu 10 1 328 B Exemption Limits for Absolute and Specific Activities radioisotope exemption limit activity specific in Bq activity in Bq/g 241 4 95Am 10 1 244 4 96Cm 10 10 252 4 98Cf 10 10 ∗ as naturally occurring isotope unlimited † in equilibrium with its daughter nuclei; the radiation exposure due to these daughter isotopes is taken account of in the exemption limits 329 C Maximum Permitted Activity Concentrations Discharged from Radiation Areas There are no universal international values for the limits of radioac- tive material that may be released from radiation areas. Different countries have defined limits based on the guidelines as recom- mended by the International Commission on Radiological Protec- tion. These limits generally refer to a maximum annual dose of 0.3 mSv that people from the general public may receive from such discharges. The table below gives some examples which have been adopted by the new German radiation protection ordinance in 2001. The corresponding limits in other countries are quite similar, but do vary in some national regulations. maximum permitted radioisotope activity concentration in air in water in Bq/m3 in Bq/m3 3 2 7 1H 10 10 7 × 2 × 6 4Be 6 10 5 10 14 × 5 6C 6 6 10 24 × 5 11Na 90 3 10 32 × 4 15P 1 3 10 42 × 2 × 5 19K 2 10 2 10 54 × 5 25Mn 20 2 10 55 5 26Fe 20 10 57 × 5 27Co 30 3 10 60 × 4 27Co 1 2 10 82 5 35Br 50 10 89 × 4 38Sr 4 3 10 90 . × 3 38Sr 0 1 4 10 330 C Maximum Permitted Activity Concentrations Discharged from Radiation Areas maximum permitted radioisotope activity concentration in air in water in Bq/m3 in Bq/m3 99m × 3 × 6 43Tc 2 10 4 10 106 . 4 44Ru 0 6 10 110m × 4 47Ag 1 4 10 109 × 4 48Cd 4 4 10 125 . × 4 53I 0 5 2 10 129 . × 3 53I 0 03 4 10 131 . × 3 53I 0 5 5 10 134 × 4 55Cs 2 2 10 137 .