Non-destructive studies of fuel pellets by neutron resonance absorption radiography and thermal neutron radiography

Direct observation of hydrogenation and dehydrogenation of a zirconium alloy

The use of ionising radiation to image nuclear fuel: A review

Applications of Neutron Radiography for the Nuclear Power Industry

Hydrogen diffusion and precipitation in duplex zirconium nuclear fuel cladding quantified by high-resolution neutron imaging

The fast and non-destructive character of neutron radiography provides the possibility of in-situ investigations of hydrogen uptake and diffusion in zirconium alloys. A special reaction furnace with neutron transparent windows was constructed. The method of quantitative hydrogen determination by neutron transmission measurements was calibrated for each experimental run. Additionally, oxygen is absorbed in the α-Zr phase and precipitated in the oxide layer. The calibration of the correlation between hydrogen and oxygen concentrations and total neutron cross-sections at room temperature and between 1123 and 1623 K are described. Results of in-situ neutron radiography investigations of hydrogen diffusion and absorption are presented in this paper. A linear dependence of the total macroscopic neutron cross section on the H/Zr atomic ratio as well as on the oxygen concentration was found. No significant temperature dependence of the total neutron cross-sections of hydrogen dissolved in β-Zr or oxygen dissolved in the α-Zr or precipitated in the oxide layer was found.

In-situ neutron radiography investigations of hydrogen diffusion and absorption in zirconium alloys

The hydrogen diffusion from the gas phase into Zircaloy-4 solid cylinders was investigated at various temperatures between 823 and 1473 K. Diffusion coefficients were fitted using axial hydrogen distributions for all temperatures investigated. The activation energy of the hydrogen diffusion was calculated for temperatures at which the bcc β phase is stable. The determined value of 48.3 kJ mol−1 K−1 is significantly higher than values published by other authors. At lower temperatures the hydrogen uptake is connected with a phase transformation from the hep α- to the bcc β-phase. The spatial phase distribution and the hydrogen concentrations in the two phases were analysed.

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M. van den Berg

Papers

In-situ neutron radiography investigations of hydrogen diffusion and absorption in zirconium alloys

In-situ investigation of hydrogen diffusion in Zircaloy-4 by means of neutron radiography