Commercial grade aluminium: A versatile reactor flux monitor

With the advent of Ge(Li) spectrometry, a high standard of purity for neutron flux monitors no longer remains an imperative “must” and becomes rather superfluous. From this standpoint, commercial grade Al was investigated for its suitability as a reactor flux monitor and was found to have a much greater practical utility than most of the monitors reported. Three Al foils and one wire were randomly selected from four different commercial sources, and analysed for their Fe, Ga, Mn and Na contents by neutron activation and high-resolution gamma-spectrometry. While Na was found to have a very heterogeneous distribution, Fe, Mn and Ga concentrations in different splits of each type of Al were consistently uniform within ±2–3%. Eight possible monitor reactions on Al, Mn, Fe and Ga have been recommended as neutron flux integrators for all the 3 components of a reactor spectrum, viz. thermal, epithermal and fast, covering a wide range of flux levels from 10⁷ to 10¹⁴n·cm⁻²·sec⁻¹. The advantages and versatility of commercial grade Al as a pile neutron dosimeter are discussed.