Simple Instrumental and Visual Tests for Nonlaboratory Environmental Control

Proposed are simple and available techniques that can be used for rapid and reliable environmental control specifically of natural water by means of instrumental and visual tests in outdoor conditions. Developed are the chemical colorimetric modes for fast detection of socially dangerous trace impurities in water such as Co(II), Pd(II), and Rh(III) as well as NO2--ions and Fe(III) serving as model impurities. Application of portable digital devices and scanner allows estimating the color coordinates and increasing the accuracy and sensitivity of the tests. The combination of complex formation with preconcentration of colored complexes replaces the sensitive but time-consuming and capricious kinetic method that is usually used for this purpose at the more convenient and reliable colorimetric method. As the test tools, the following ones are worked out: polyurethane foam tablets with sorbed colored complexes, the two-layer paper sandwich packaged in slide adapter and saturated by reagents, and polyethylene terephthalate blister with dried reagents. Fast analysis of polyurethane foam tablets is realized using a pocket digital RGB-colorimeter or portable photometer. Express analysis of two-layer paper sandwich or polyethylene terephthalate blister is realized by visual and instrumental tests. The metrological characteristics of the developed visual and instrumental express analysis techniques are estimated

Recent results on high thermal energy load testing of beryllium for ITER first wall application

In this paper, progress in the high heat flux (HHF) qualification testing of TGP-56FW beryllium grade for ITER first wall applications is presented. Two actively cooled Be/CuCrZr brazing mock-ups were tested under complex thermal loading conditions in the electron beam facility JUDITH-1 (step 1: vertical displacement event test at 40 MJ m−2, 0.3 s, 1 shot; step 2: disruption tests at 3 MJ m−2, 1 shot, Δt=5 ms; step 3: repetitive fatigue test at 80 MW m−2, 1000 shots, Δt=25 ms). After testing, metallographic investigations on the microstructure and crack morphology were carried out. The results of these studies of Be tiles are reported and discussed. The overall results of TGP-56FW grade qualification testing have demonstrated the reliable performance capability of TGP-56FW for application as the armor of the ITER first wall. In addition, the results of first experiments with TGP-56FW and S-65C beryllium grades in the QSPA-Be plasma gun facility are also reported. In these experiments, beryllium tiles (80×80×10 mm3) were tested in a hydrogen plasma stream (5 cm in diameter) with pulse duration 0.5 ms and heat loads of 0.5–2 MJ m−2. Experiments were performed at room temperature. The evolution of the surface microstructure and mass loss of beryllium exposed to up to 100 shots is presented

Stainless Steel Performance under ITER-Relevant Mitigated Disruption Photonic Heat Loads

ITER grade stainless steel (SS) 316L(N)-IG was tested in QSPA-T (photons) and JUDITH (electrons) under heat loads relevant to those expected from photon radiation on the ITER diagnostic first wall (DFW) during disruptions mitigated by massive gas injection. Repeated pulses slightly above the melting threshold eventually lead to a regular, “corrugated” SS surface, with hills and valleys spaced by 1–2 mm. The negligible mass loss observed after the heat pulses indicates that hill growth (growth rate of ∼1–2 μm per pulse) and SS plate thinning in the valleys is a result of melt-layer redistribution. A Similar behavior is observed on SS samples exposed in QSPA-T (pulse length 0.5 ms) and JUDITH (pulse length ⩽ 3.0 ms) at the same heat flux factor. The combined data suggests, for the total lifetime, a surface roughening of ⩽1.5 mm on parts of the ITER SS DFW exposed to the highest transient photon loads, after 1200 mitigated disruptions at high stored energy. The results also indicate that the surface roughness increase may be significantly reduced by variation of the SS impurity composition. This experimental observation is supported by a proposed theoretical mechanism for the surface roughness formation based on the growth of capillary waves in the melt layer

Nano-scale structural features of stratified hydrocarbon films formed at interaction of plasma with surface in T-10 tokamak

Hydrocarbon films and flakes (i.e. free standing films) with high atomic deuterium to carbon ratio formed at deuterium plasma discharges in T-10 tokamak are non-crystalline. They contain structure elements of cluster/nanopore type with typical sizes of about 1 nmand interplane distances between X-ray scattering structures of 0.7, 0.24 and 0.12 nm. Structural sp2- carbon states were found mainly on the wall side of flakes, and sp3-hybridized carbon states—on their plasma side. In situ monitoring of films growth and hydrogen isotope accumulation in them by means of Fourier-transform infrared (FT-IR) spectroscopy is proposed. The computational modeling of X-ray scattering by random ensembles of carbon nanostructures of various types suggests that a strong peak of X-ray diffraction (XRD) intensity may be caused by the toroids (toroidal carbon nanotubes) with torus radius of about 1 nm.

Recrystallization and modification of the stainless-steel surface relief under photonic heat load in powerful plasma discharges

Targets made of ITER-grade 316L(N)-IG stainless steel and Russian-grade 12Cr18Ni10Ti stainless steel with a close composition were exposed at the QSPA-T plasma gun to plasma photonic radiation pulses simulating conditions of disruption mitigation in ITER. After a large number of pulses, modification of the stainless-steel surface was observed, such as the formation of a wavy structure, irregular roughness, and cracks on the target surface. X-ray and optic microscopic analyses of targets revealed changes in the orientation and dimensions of crystallites (grains) over a depth of up to 20 μm for 316L(N)-IG stainless steel after 200 pulses and up to 40 μm for 12Cr18Ni10Ti stainless steel after 50 pulses, which is significantly larger than the depth of the layer melted in one pulse (∼10 μm). In a series of 200 tests of ITER-grade 316L(N)-IG ITER stainless steel, a linear increase in the height of irregularity (roughness) with increasing number of pulses at a rate of up to ∼1 μm per pulse was observed. No alteration in the chemical composition of the stainless-steel surface in the series of tests was revealed. A model is developed that describes the formation of wavy irregularities on the melted metal surface with allowance for the nonlinear stage of instability of the melted layer with a vapor/plasma flow above it. A decisive factor in this case is the viscous flow of the melted metal from the troughs to tops of the wavy structure. The model predicts saturation of the growth of the wavy structure when its amplitude becomes comparable with its wavelength. Approaches to describing the observed stochastic relief and roughness of the stainless-steel surface formed in the series of tests are considered. The recurrence of the melting-solidification process in which mechanisms of the hill growth compete with the spreading of the material from the hills can result in the formation of a stochastic relief