Dresden 2009 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 49: Hydrogen in Metals

MM 49.3: Vortrag

Freitag, 27. März 2009, 10:45–11:00, IFW D

Quantitative determination of the hydrogen in zirconium with high spatial resolution by means of neutron radiography — •Mirco Große — Forschungszentrum Karlsruhe, Germany

Due to the high total neutron cross section of hydrogen, neutron radiography is a powerful tool for quantitative hydrogen determination in a lot of materials with a spatial resolution up to 0.030 mm.

As example, studies of the hydrogen uptake during steam oxidation of zirconium based alloys applied as nuclear fuel cladding materials are given.

Correlation parameters between the total neutron cross section of the sample and its hydrogen content were determined. At H/Zr atomic ratios lower than 1.0, linear correlations between the hydrogen content and total cross section exist. The total cross section of Zr is lower and the effect of the hydrogen is higher in radiography measurements with a cold neutron spectrum than with a thermal spectrum.

After an initial phase a dynamical equilibrium is established between the hydrogen released into the gas phase and absorbed into the remaining metal. Due to the parabolic oxidation kinetics the hydrogen concentration decreases by the power of -1/4 with time.

The method provides also the possibility of in-situ measurements. Examples for the hydrogen uptake during isothermal steam oxidation will be given.