On the Use of Chromium Coating for Inner-Side Fuel Cladding Protection: Thickness Identification Based on Fission Fragments Implantation and Damage Profile

Inner-side coatings have been proposed as a complementary solution within the accident tolerant fuel (ATF) framework, to provide enhanced protection for the nuclear fuel cladding. Unlike external surface, the degradation of irradiated internal cladding surface has not been studied extensively. Fission fragments produced during the fission of nuclear fuel is one of the key players in this degradation. This study aimed to estimate the minimum thickness of the thin chromium film, required to protect the inner side of the nuclear fuel cladding. The approach used is based on a set of calculations, of Ion ranges and damage profiles, for a group fission fragments, using the TRIM code. The calculation results were verified by comparison with the experimental data associated with the phenomena of the inner cladding degradation of thermo-releasing elements. The recommended minimum thickness for such a film was found to be 9 microns. Calculations also showed that chromium metal has a greater stopping power compared to the zirconium-based alloy E110, which indicates an increased ability of chromium to withstand exposure to energetic fission fragments during reactor operation

Hydrogen absorption by Zr-1Nb alloy with TiN[x] film deposited by filtered cathodic vacuum arc

This paper describes the opportunity of titanium nitride (TiNx) films application as protective coating for Zr-2.5Nb alloy from hydrogenation. Dense TiN[x] films were prepared by filtered cathodic vacuum arc (CVA). Hydrogen absorption rate was calculated from the kinetic curves of hydrogen sorption at elevated temperature of the sample (T=673 K) and pressure (P=2 atm). Results revealed that TiN[x] films significantly reduced hydrogen absorption rate of Zr-2.5Nb

The formation of stable hydrogen impermeable TiN-based coatings on zirconium alloy Zr1%Nb

TiN coatings were deposited by DC reactive magnetron sputtering (dcMS) method on Zr1%Nb substrates with different film thickness. The influence of crystalline structure and thickness of the coatings on hydrogen permeation was investigated. The results revealed that the increase in thickness of the film reduced hydrogen permeability. 1.54 [mu]m TiN deposited in N[2]/Ar gas mixture with a ratio of 3/1 reduces hydrogen permeation in more than two orders of magnitude at 350 °С. Adhesion strength decreased with increasing film thickness (0.55 to 2.04 [mu]m) from 7.92 to 6.65 N, respectively. The Ti underlayer applied by arc ion plating (AIP) leads to the formation of stable Ti/TiN coatings on Zr1%Nb under thermocycling conditions up to 800 °С. Meanwhile, hydrogen permeation rate of Ti/TiN deposited by combination of AIP and dcMS remains at the same level with TiN deposited by dcMS

Study of the plasma immersion implantation of titanium in stainless steel

The results of the study of the pulsed plasma-immersion ion implantation of titanium in steel Cr18Ni10Ti depending on the time (dose) implantation are presented. It is shown that the change of the element and the phase composition of the surface layers and their microscopic characteristics and mechanical properties (hardness, wear resistance) depending on the implantation time is not monotonic, but follows to a certain rule. The possibility of interpretation of the obtained results in the thermal spike concept of the generation on the surface by the stable (magic) clusters is discussed. This concept follows logically from the recent studies on the plasma arc composition and from a polyatomic clusters-surface interaction

Hydrogenation of Zr-2.5Nb alloy after plasma-immersion titanium implantation

The study results of the influence of plasma-immersion ion implantation of titanium in Zr-2.5Nb on hydrogenation are presented. The titanium implantation was carried out in two modes: with active plasma filtering (APF) and passive plasma filtering (PPF). The results of total hydrogen concentration, absorption rate, XRD analyses and depth distribution of elements revealed that modified surface layer after titanium ion implantation is formed hydrogen diffusion barrier reduces hydrogen absorption by Zr-2.5Nb

Introduction of hydrogen into titanium by plasma methods

The introduction of hydrogen into titanium VT1-0 by the methods of plasma-immersion ion implantation (PIII) from the hydrogen plasma of a source with a heated cathode and into high-frequency discharge (HFD) plasma was studied. Modes of installations for introduction are chosen proceeding from the requirement of the maximum content of hydrogen in the samples. It is established that saturation from the HFD-plasma leads to a significant enrichment to a depth of 1.2 µm, at the introduction of hydrogen by the PIII this depth is 0.6 µm. The hydrogen content of 0.06 wt.% in the samples after saturation in the HFD plasma, and 0.049 wt.% after PIII. During PIIII (with an energy of 0.9-1.5 keV), hydrogen is strongly scattered by the surface of the sample and is captured predominantly by surface defects (including those created by the ions themselves), as well as by vacancies in the near-surface layers. Upon saturation from the HFD-plasma, hydrogen diffuses into the interior of the sample and settles in interstices and at grain boundaries. At the same time, saturation from the HFD plasma and PIII lead to significant change in the crystal parameters and the creation of hydride phases