Determination of diffusion coefficients of hydrogen and deuterium in Zr–2.5%Nb pressure tube material using hot vacuum extraction-quadrupole mass spectrometry

Hydrogen Effect on Zr-Nb-Mn Alloys for Nuclear Reactor Application

“…These values are in agreement with hydrogen gas permeation technique results 15,20 and with extractionquadrupole mass spectrometry result 17 . As expected, the alloy with higher manganese content (Zr-0.6Nb-0.4Mn), which has the highest precipitate volume fraction, presented the highest solubility, once it has more interfaces that act as hydrogen traps, increasing the hydrogen solubility.…”

“…This suggests the existence of one reaction during hydrogen desorption at 300ºC independent of the analyzed composition. Although hydrogen gas permeation technique is currently used to determine the coefficient diffusion of materials; however, for some zirconium alloys, as Zr-1Nb, hydrogen diffusivity is very low and atoms do not permeate through the sample due to the formation of a hydride front 15,17 , preventing hydrogen diffusion and the flux data acquisition. As an alternative, Kirchheim 9 proposed the determination of hydrogen diffusion flux through the integration of TDS peak, Equation 2.…”

“…As an alternative, Kirchheim 9 proposed the determination of hydrogen diffusion flux through the integration of TDS peak, Equation 2. Therefore, Shrivastava et al 17 used extractionquadrupole mass spectrometry and constant temperatures to estimate the hydrogen diffusivity parameters for a Zr-2.5Nb alloy. Both studies obtained the diffusion coefficients using Equation 1.…”

Hydrogen Embrittlement and Oxide Layer Effect in the Cathodically Charged Zircaloy-2

“…at room temperature. The maximum hydrogen content of H/Zr = 0.9 (which is still in the single-phase β-Zr region) was obtained at 1230 K and 100 kPa of gas hydrogen pressure [18].The diffusivity of H in Zr can be expressed as 5.468 × 10 −7 exp(−45293/RT) m 2 /s [28]. Two stable hydride phases, δ-hydride (fcc) and ε-hydride (fct), and a metastable phase, γ-hydride (fct), may appear at different temperature and hydrogen content [29].…”

“…The oxide pores provide short circuits for oxygen and hydrogen diffusion [33], as well as the sites to form molecular hydrogen [34]. A presence of oxygen may affect hydrogen absorption, as hydrogen can be trapped by oxygen atoms positioned along the preferred path creating the O-H bonds [28,35].The presence of hydrogen has diverse effects on mechanical properties, which are related to hydrogen content and temperature. The softening is assumed to be due to interstitial hydrogen solution and appears at low hydrogen content resulting in a decrease in Young's modulus, shear modulus, and microhardness [36,37], and demonstrates an entirely ductile fracture [20,38].…”