We propose a novel use of a non-destructive technique to quantitatively assess hydrogen concentration in zirconium alloys. The technique, called Cold Neutron Prompt Gamma Activation Analysis (CNPGAA), is based on measuring prompt gamma rays following the absorption of cold neutrons, and comparing the rate of detection of characteristic hydrogen gamma rays to that of gamma rays from matrix atoms. Because the emission is prompt, this method has to be performed in a reactor such at the National Institute of Technology (NIST). Determination is simple and is shown here to be accurate, matching the results given by usual destructive techniques such as Vacuum Hot Extraction (VHE), with a precision of mg.kg-1 (or wt.ppm). Very low levels of hydrogen (as low as 5wt.ppm) can be detected. Also, it is demonstrated that CNPGAA can be used sequentially on an individual corrosion coupon during autoclave testing, to measure a gradually increasing hydrogen concentration. Thus, this technique can replace destructive techniques performed on sister samples, which inherently yield greater experimental uncertainty results. In this study, the technique is developed for use in the measurement of hydrogen concentration in zirconium alloys.
Citation: Journal of Nuclear Materials
Pub Type: Journals
hydrogen, zirconium, prompt gamma rays, activation analysis, vacuum extraction, embrittlement, corrosion