Hydrogen in Zircaloy-4: effects of the neutron irradiation on the hydride formation
- 229 Downloads
X-ray diffraction patterns of neutron irradiated Zircaloy-4 samples were obtained at the Brazilian Synchrotron Light Laboratory (LNLS) to study the effects of the fast neutron fluxes and post-irradiation thermal treatments on the zirconium hydride evolution. The high intensity and resolution of the synchrotron beam allowed to detect the (111)δ and (220)δ diffraction peaks of the ZrH1.5 + x (0 ≤ x≤ 0.16) δ-phase in unirradiated Zircaloy-4 samples having a hydrogen concentration as low as 0.2 at.% (20 wppm). Then, irradiated samples, that were taken from the Zircaly-4 core components of the argentine HWPR Atucha I Nuclear Power Plant (CNA-1) were studied with that radiation to detect the diffraction peaks of ZrH1.5 + x δ-phase particles precipitated in samples having hydrogen isotope concentration lower than 2 at.% (220 wppm). A significant increment of the (111)δ and (220)δ peak areas were observed at room temperature after post-irradiation thermal treatments at 600 °C during 4 h. These results indicate that after the annealing a hydrogen concentration between 35 to 70 wppm, which were apparently absent in the irradiated samples has precipitated at room temperature as zirconium hydrides. That amount was estimated from a (220)δ peak area versus the bulk H concentration regression line, made with unirradiated samples. These results get support to a hydrogen trapping hypothesis proposed in previous works. In addition, it has been shown that the zirconium hydride that precipitate in the irradiated samples have the equilibrium δ-ZrH1.5 + x cubic crystalline structure.
KeywordsHydride Irradiate Sample Irradiate Material Unirradiated Sample Hydrogen Trapping
We are grateful for the support given by the Brazilian Synchrotron Light Laboratory (LNLS) under proposal D12A-XRD1–2805. In addition we are in debt with Aldo F. Craievich for his kindness assistance.
- 3.Mc Minn A, Darby EC, Schofield JS (1998) Twelfth International Symposium: Zirconium in the Nuclear Industry, Toronto. ASTM, STP 1354. p 173Google Scholar
- 5.Zuzek E, Abriata JP, San Martín A (1990) Bulletin of alloy phase diagrams, vol 11, No. 4, p 385Google Scholar
- 7.Chung HM, Daum RS, Hiller JM, Billone MC (2001) Zirconium in the Nuclear Industry: 13th International Symposium. ASTM STP 1423, Annecy, p 561Google Scholar
- 8.Yang WJS (1989) Effect of radiation on materials: 14th International Symposium, vol 1. ASTM STP 1046, Philadelphia, p 442Google Scholar
- 9.Kruger RM (1990) EPRI NP 6845-DGoogle Scholar