Measurement of inclusive photonuclear (γ,n) reaction cross section for 129I

Long-life non-γ emitting radioactive wastes such as 129I and 14C are produced from nuclear waste facilities. The photonuclear reaction is supposed to be usable for measuring the quantity of such nuclides without the destruction of the waste drum. Photonuclear products of 128I and 13C emit gamma rays and their radiation can be easily detected by a Ge detector. In this study, the inclusive photonuclear reaction cross section of 129I(γ,n)128I was measured by the use of Bremsstrahlung photons from 30-MeV electron Linac. The amount of produced 128I was measured with an HPGe gamma-ray spectrometer. Experiments were analyzed for both (γ,n) and accompanying (n,γ) reactions. Flux calculations were performed by EGS and MCNP codes. The measured average activation cross section of 129I(γ,n)128I is (0.096 ± 0.005) barn on the basis of 197Au(γ,n) reaction value. The measured value agrees with the evaluated (IAEA photonuclear data library) cross section within a deviation of 17%. The cross section is usable for non-destructive measurement of the amount of 129I in radioactive waste. (authors)