Zirconium Hydrides and Hafnium Hydrides

First-Principles Prediction of Ternary Interstitial Hydride Phase Stability in the Th–Zr–H System

“…(a) F solids = E 0 , (b) F solids = E 0 + F vib ( T ), and (c) F solids = E 0 + F vib ( T ) – TS ThZr 2 H 6 conf . Experimental values for metal hydride decomposition temperatures, T d , are 1250 K (ThZr 2 H 6 ), 1154 K (ZrH 2 ), , 1154 K (ThH 2 ), and 636 K (Th 4 H 15 )…”

“…One expects that diffusion barriers to form the most thermodynamically stable state are reduced at high temperatures. An apparent exception to this metastability rule is the ThZr 2 –H system, in which stable ternary interstitial metal hydrides ThZr 2 H x have been isolated and characterized experimentally. ,, ThZr 2 H 6 dissociates at T d ≈ 1250 K , compared with T d ≈ 1150 K (637 K) for ZrH 2 , and ThH 2 (Th 4 H 15 ) . This system is of interest because the U–Th–Zr hydride fuel absorbs more hydrogen at high temperature than U–Zr hydride fuels .…”

Characterization of hydrogen concentration in Zircaloy-4 using ultrasonic techniques

“…Table 2 shows values of density and elastic modulus reported in literature. The ratio E/q of zirconium hydride is lower than that of zirconium when the values reported by Beck and Mueller [19] are employed. This effect was argued by De et al [10] to explain the reduction in velocity detected for hydrogen levels lower than 100 ppm in presence of c phase.…”

Feasibility Study of Supercritical Light Water Cooled Fast Reactors for Actinide Burning and Electric Power Production, 3rd Quarterly Report

“…However, at the specified low levels of oxygen impurities in reactor-grade zirconium (<1000 wt ppm or <1 at. %) this effect is expected to be negligible [Beck and Mueller 1968]. Finally, it should be emphasized that uniform and cost effective hydriding of zirconium parts with cross sections as wide as 7 cm has been successfully performed in the past; the proposed moderator rods for the SCWR fall well within this established range.…”