Volume 3, Issue 2 (February 2006)
Gas Production in Reactor Materials
This paper presents an overview of the principal nuclear reactions that are known to produce hydrogen and helium in irradiated materials and a summary of the comparison of measurements with predictions in various reactors. Hydrogen and helium are produced in all reactor materials by fast neutron reactions which typically have thresholds above 4 MeV. Selected elements also have thermal neutron gas production reactions that can be quite prolific, such as 6Li, 10B, and 14N, and there are a number of elements which produce transmutation products that have high thermal neutron gas production cross sections, most notably 59Ni produced by irradiation of Ni and 65Zn produced by irradiation of Cu or Zn. Since gas production cross sections are isotope-specific, gas production rates can change during irradiation due to transmutation effects or initial rates can be modified by isotopic tailoring of reactor materials.