Determination of Deuterium Pick-Up in Zr-Nb Alloy by Hot Vacuum Extraction-Quadrupole Mass Spectrometry

摘要

Zirconium alloys are used extensively by the nuclear industry as reactor core components. In pressurized heavy water reactors (PHWRs) zirconium-niobium alloy pressure tubes (also called coolant channels) are used with D _2O as the primary heat transport fluid. Due to continuous usage of the pressure tubes inside the reactor, heavy ingress of deuterium into the pressure tubes due to corrosion reactions could occur resulting in hydrogen (or deuterium) embrittlement. Aging management therefore requires that this deuterium pick-up rate should be quantified for the remedial measures to be taken for the smooth operation of the reactor. For this purpose, a hot vacuum extraction-quadrupole mass spectrometry (HVE-QMS) technique has been developed in our laboratory. Experimental conditions like temperature, time of extraction of liberated gases, and measurement methodology have been optimized. Sensitivity factors have been derived for quantification of analytical results. Precision of the methodology was found to be 10%. Also, detailed studies have been carried out on the formation of hydrogen (or deuterium) molecular ion H ~+ _3(D ~+ _3) in QMS as a function of pressure in the measurement system and its possible effect on the results.