Overview of R&D at TLK for process and analytical issues on tritium management in breeder blankets of ITER and DEMO

Safe, reliable, and efficient tritium management in the breeder blanket will have to face unprecedented technological challenges. Beside the efficiency for tritium recovery from the breeder blanket (Tritium Extraction (TES) and Coolant Purification Systems (CPS)), the accuracy for tritium tracking between the inner and the outer fuel cycle must also be demonstrated. This paper focuses on the recent R&D carried out at the Tritium Laboratory Karlsruhe to tackle these issues. For ITER, the recently consolidated TES and CPS designs comprise adsorption columns and getter beds operated in semi-continuous mode. Different approaches for the tritium accountancy stage (TAS) have been evaluated. Balancing static (batch-wise gas collection at the TBM outlets and the tritium plant) or dynamic (in/on-line) approaches with respect to the expected analytical performances and integration issues, the first conceptual design of the TAS for EU TBMs is presented. For DEMO, the overall strategy for tritium recovery and tracking has been revisited. The necessity for on-line real-time tritium accountancy and improved process efficiency suggest the use of continuous processes such as permeator and catalytic membrane reactor. The main benefits combining the PERMCAT process with advanced membranes is discussed with respect to process improvements and facilitated accountancy using spectroscopic methods.     

Effect of maturation and freezing on quality and drying kinetics of beef

The quality of dried meat products and their drying kinetics significantly depends on the status of the raw material going into the drying process. The aim of this study was to determine the impact of meat status (fresh, mature, frozen–thawed) on the drying kinetics and the resulting quality in terms of color changes and spectrally deductible information. Drying tests were conducted using meat from organically raised bulls. In the fresh meat, freezing leads to a decrease in the drying rate, while for matured meat, the opposite is true. Aging and freezing have little effect on the end product quality in terms of final product color. However, water content can be detected hyperspectrally and resolved spatially for all stages of the process. With regard to water content prediction, the Monte-Carlo uninformative variable elimination-partial least square method performs best for the fresh and fresh frozen–thawed version with seven wavelengths, an r² of 0.97 and 0.88, and RMSE (Root mean squared error) of 0.15 and 0.17 for the test set, respectively.     

Mechanical gradient interphase by interdiffusion and antiplasticisation effect—study of an epoxy/thermoplastic system

A stoichiometric amine-epoxy formulation was cured in the presence of a thermoplastic, namely poly(vinylpyrrolidone) (PVP). The epoxy system consisted of the resin diglycidyl ether of bisphenol A (DGEBA) and the aromatic curing agent 4,4′-diaminodiphenylsulfone (DDS). As shown for this system in a former study by Oyama et al. [Oyama HT, Lesko JJ, Wightman JP. J Polym Sci B 1997;35:331-46. [36]], preferential absorption of amine molecules by PVP can occur. In the present study, the focus is on the variations of local elastic properties within the epoxy interphase adjacent to the PVP layer. The curing was performed close to the glass transition temperature, T_α, of the PVP film, namely at 170 °C. Variations of the local amine concentration were tracked using energy-dispersive analysis of X-rays (EDX), by taking benefit of the sulfur contained in DDS. Using temperature-dependent dynamic mechanical analysis (DMA), a series of epoxy reference samples of different amine-epoxy concentration ratios, r, was investigated in order to work out the relationship between r and the epoxy storage modulus at room temperature. In the excess-epoxy regime, r<1, the modulus is observed to increase with departure from the stoichiometric ratio, r=1. Considering the respective suppression of the β-transition, the observed characteristic can be explained by an antiplasticisation effect. Depth-sensing indentation (DSI) experiments across the epoxy/PVP interphase provided evidence for strong modulus variations. In consistency with the EDX and the DMA data, in the vicinity of the PVP layer the local epoxy modulus is increased. The total change of the epoxy Young's modulus is ∼1.1 GPa. However, the total width of the modulus decay of ∼175 μm is ∼2.5 times larger than the one of the DDS concentration gradient. This finding is discussed in terms of additional spatial variations of the DGEBA concentration as well as long-range diffusion currents of DDS induced by the interdiffusion processes and their effect on the final network of crosslinks.     

Electrochemical routes for environmentally friendly recycling of rare-earth-based (Sm–Co) permanent magnets

Journal of Applied Electrochemistry - The consumption of critical raw materials, especially those in permanent magnets of Nd–Fe–B and Sm–Co-type, has significantly grown in the...     

Variation of Intumescent Coatings Revealing Different Modes of Action for Good Protection Performance

Thermal insulation and mechanical resistance play a crucial role for the performance of an intumescent coating. Both properties depend strongly on the morphology and morphological development of the foamed residue. Small amounts (4 wt%) of fiberglass, clay and a copper salt, respectively, are incorporated into an intumescent coating to study their influence on the morphology and performance of the residues. The bench scale fire tests were performed on 75 × 75 × 2 mm³ coated steel plates according to the standard time–temperature curve in the Standard Time Temperature Muffle Furnace⁺ (STT Mufu⁺). It provided information about foaming dynamics (expansion rates) and thermal insulation. Adding the copper salt halved the expansion height, whereas the clay and fiberglass change the height of the residue only moderately. The time to reach 500°C was improved by 31% for clay and 15% for the other two fillers. Nondestructive micro computed tomography is used to assess the inner structure of the residues. A transition of the residue from a black, carbonaceous foam with closed cells into an inorganic, residual open cell sponge occurs at high temperatures. This transition is due to a loss of carbon; the change in microstructure is analyzed by scanning electron microscopy. Additional mechanical tests are performed and interpreted with respect to the results of the morphology analysis. Adding clay or copper salt improved the mechanical resistance tested by a factor 4. The additives significantly influence the thickness and foaming dynamics as well as the inner structure of the residues, whereas their influence on insulation performance is moderate. In conclusion, different modes of action are observed to achieve similar insulation performance during the fire test.     

Silicon temperature measurement by infrared absorption. Fundamentalprocesses and doping effects

The fundamental absorption mechanisms in silicon at 1.30 and 1.55 μm have been investigated in the temperature range of 500-800°C. For lightly doped wafers in this temperature range, the absorption at 1.55 μm is by free carriers. and that at 1.30 μm is predominantly by bandgap absorption. The effect of heavy substrate doping on infrared absorption at an elevated temperature has also been studied, and it was found that doping has little effect below levels of 7×10¹⁷ cm^-3. Above that level, the temperature dependence of free carrier absorption strongly affects the transmission as a function of temperature. The knowledge of the fundamental absorption processes is then used to predict the ultimate temperature ranges over which the technique will be useful     

Migration of single-stranded DNA in polyacrylamide gels during electrophoresis

By using fluorescence recovery after photobleaching (FRAP) and electric birefringence, the migration of single-stranded DNA in polyacrylamide gels and orientation as a response to an electric pulse were investigated. Electrophoretic mobility is in good agreement with the model of biased reptation including fluctuations. The determination of the electrophoretic mobility in solution, mu0, allows an estimation of the gel pore diameter seen by the molecule. As previously observed for double-stranded DNA, the electric birefringence results from two processes: the alignment of the molecule along the electric field and the elongation of the primitive path in the gel, for long single-stranded DNA (>2000 bases). The combination of results obtained with the two techniques allows us to propose experimental conditions to improve the separation of single-stranded DNA with pulsed field techniques.     

Biodegradability of nonionic surfactants: Screening test for predicting rate and ultimate biodegradation

Environmental water quality evaluations of raw materials in consumer products occupy a position of critical importance in many industries throughout the world. The rapid growth and diversity of the household detergent market requires continuous consideration of new materials needed to meet the demands of new, improved and modified products. As household cleaning products are normally disposed of as a component of domestic sewage, surface active compounds, including nonionic surfactants, would reach surface waters only as a part of a sewage effluent and would be subject to the same degree of biological treatment as the balance of the waste. For this reason, evaluations of such new materials include an environmental assessment in which biodegradability testing of organic materials is an important first step. Biodegradability characteristics of nonionic surfactants, as a class, are generally more difficult to ascertain because of wide structural diversity and a usual lack of functional groups. Such determinations usually involve intricate and laborious test methods which necessitate development of analytical techniques for each degradation product of a given material. A method has been developed, modified and used in our laboratory, that provides, after reasonable opportunity for biological acclimation, a measure of the rate and degree of ultimate biodegradation (conversion to CO₂ and H₂O). This method, which uses simple equipment, has been used to assess the biodegradability of a wide variety of nonionic surfactants, without necessitating the development of specific analytical methods for each surfactant under consideration. Additionally, this method can be adapted to measure degradation under conditions of anaerobiosis or low temperature.