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

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

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