An activation product is a material that has been made radioactive by the process of neutron activation. Process Fission products and actinides produced by neutron absorption of nuclear fuel itself are normally referred to by those specific names, and activation product reserved for products of neutron capture by other materials, such as structural components of the nuclear reactor or nuclear bomb, the reactor coolant, control rods or other neutron poisons, or materials in the environment. In these cases their production is undesired and they need to be handled as radioactive waste. Some nuclides can be produced both as activation products or as fission products. For example molybdenum-99 which is an important nuclide in "molybdenum cows" used in medical diagnostics can be produced either by fissioning 235U or by neutron irradiation of 98Mo. Practical uses However, neutron activation (usually in a dedicated research reactor, but sometimes also in power reactors like the CANDUs at Bruce nuclear generating station) is also used deliberately to produce desired radioisotopes for uses in food irradiation, nuclear medicine and to sterilize equipment via gamma radiation emitted from isotopes such as Cobalt-60.
Activation products in a reactor's primary coolant loop are a main reason reactors use a chain of two or even three coolant loops linked by heat exchangers.
Fusion reactors will not produce radioactive waste from the fusion product nuclei themselves, which are normally just helium-4, but generate high neutron fluxes, so activation products are a particular concern. List of activation products Activation product radionuclides include:
+ Half-lives and decay branching fractions for activation productsNuclideHalf-lifeDecay modebranching fractionSourceNotes12.312 ± 0.025 yβ−1.0LNHB( 1.51 ± 0.06 ) × 106 yβ−1.0ENSDF( 5.7 ± 0.03 ) × 103 yβ−1.0LNHB2.449 ± 0.005 sβ−1.0ENSDF7.13 ± 0.02 sβ−1.0ENSDF26.88 ± 0.05 sβ−1.0ENSDF950.57 ± 0.23 dε0.1011 ± 0.0002aIAEA-CRP-XGβ+0.8989 ± 0.0002a0.62329 ± 0.00006 dβ−1.0IAEA-CRP-XG9.458 ± 0.012 mβ−1.0ENSDF( 7.17 ± 0.24 ) × 105 yε0.1825 ± 0.0023bLNHBβ+0.8175 ± 0.0023b87.32 ± 0.16 dβ−1.0LNHB( 0.01 ± 0.03 ) × 105 yε0.019 ± 0.001LNHBβ−0.981 ± 0.001269 ± 3 yβ−1.0ENSDF109.61 ± 0.04 mβ−1.0ENSDF( 4.563 ± 0.013 ) × 1011 dε0.1086 ± 0.0013aIAEA-CRP-XGβ−0.8914 ± 0.0013a12.36 ± 0.012 hβ−1.0ENSDF( 1.02 ± 0.07 ) × 105 yε1.0ENSDF162.61 ± 0.09 dβ−1.0ENSDF3.3492 ± 0.0006 dβ−1.0ENSDF43.67 ± 0.09 hβ−1.0ENSDF27.7009 ± 0.002 dε1.0IAEA-CRP-XG312.29 ± 0.26 dε1.0IAEA-CRP-XG0.107449 ± 0.000019 dβ−1.0IAEA-CRP-XG( 1.0027 ± 0.0023 ) × 103 dε1.0IAEA-CRP-XG44.494 ± 0.013 dβ−1.0IAEA-CRP-XG271.8 ± 0.05 dε1.0IAEA-CRP-XG70.86 ± 0.06 dβ+0.15 ± 0.0020aIAEA-CRP-XGε0.85 ± 0.0020a( 1.92523 ± 0.00027 ) × 103 dβ−1.0IAEA-CRP-XG( 7.6 ± 0.5 ) × 104 yε1.0ENSDF98.7 ± 2.4 yβ−1.0LNHB2.51719 ± 0.00026 hβ−1.0ENSDF0.52929 ± 0.00018 dβ+0.179 ± 0.002aIAEA-CRP-XGβ−0.39 ± 0.003aε0.431 ± 0.005a5.12 ± 0.014 mβ−1.0ENSDF243.86 ± 0.2 dβ+0.0142 ± 0.0001aIAEA-CRP-XGε0.9858 ± 0.0001a( 5.73 ± 0.22 ) × 103 dIT1.0IAEA-CRP-XG( 4.0 ± 0.8 ) × 103 yε1.0ENSDF0.250281 ± 0.000022 dβ−0.000037 ± 0.000006aIAEA-CRP-XGIT0.999963 ± 0.000006a249.85 ± 0.1 dIT0.0136 ± 0.0008aIAEA-CRP-XGβ−0.9864 ± 0.0008a4.486 ± 0.004 hβ−0.05 ± 0.008ENSDFIT0.95 ± 0.00812.93 ± 0.05 dβ−0.473 ± 0.006ENSDFε0.527 ± 0.00670 ± 2 dε1.0ENSDF42.39 ± 0.06 dβ−1.0ENSDF114.43 ± 0.04 dβ−1.0ENSDF121.2 ± 0.2 dε1.0ENSDF75.1 ± 0.3 dβ−1.0ENSDF23.72 ± 0.06 hβ−1.0ENSDF2.695 ± 0.0007 dβ−1.0IAEA-CRP-XG64.14 ± 0.05 hε1.0ENSDF46.594 ± 0.012 dβ−1.0IAEA-CRP-XG
LNHB Laboratoire National Henri Becquerel, Recommended Data, http://www.nucleide.org/DDEP_WG/DDEPdata.htm , 5 June 2008. IAEA-CRP-XG M.-M. Bé, V.P. Chechev, R. Dersch, O.A.M. Helene, R.G. Helmer, M. Herman, S. Hlav ác, A. Marcinkowski, G.L. Molnár, A.L. Nichols, E. Schönfeld, V.R. Vanin, M.J. Woods, IAEA CRP "Update of X Ray and Gamma Ray Decay Data Standards for Detector Calibration and Other Applications", IAEA Scientific and Technical Information report STI/PUB/1287, May 2007, International Atomic Energy Agency, Vienna, Austria, . ENSDF Evaluated Nuclear Structure Data File, http://www-nds.iaea.org/ensdf/, 5 June 2008.
Branching fractions from LNHB database.
Branching fractions renormalised to sum to 1.0..
References
External links Handbook on Nuclear Activation Cross-Sections, IAEA, 1974 Nuclear Structure and Decay Databases (nndc.bnl.gov) New and revised half-life measurements results made by the Radioactivity Group of NIST HANDBOOK OF NUCLEAR DATA FOR SAFEGUARDS: DATABASE EXTENSIONS, AUGUST 2008