Thermo-mechanical analyses and assessment with respect to the design codes and standards of the HCPB-TBM Breeder Unit

The Helium Cooled Pebble Bed-Test Blanket Module (HCPB-TBM) is one of the two breeding blanket concepts currently under development in Europe. Key component of the HCPB-TBM, the Breeder Unit (BU), has entered the detailed engineering design phase. After establishing a base design, thermal and thermo-mechanical analyses have been performed under typical ITER operational conditions: the results are presented and discussed in this paper.A full scaled finite element model of the base design of the HCPB-TBM BU has been built to run thermal analyses of the beryllium and Li₄SO₄ pebble beds and thermo-mechanical analyses of the BU structure, both in steady state and in a typical transient regime during a pulse of the ITER D–T phase. The temperatures reached in the Li₄SO₄ and beryllium pebble beds in the BU base design are 930.8 °C and 712.9 °C, respectively, which are above the recommended values of 920 °C for Li₄SO₄ and 650 °C for the beryllium pebbles. The maximum temperature in the structural steel is 548.4 °C, which remains under the design limit defined for the TBM studies (550 °C). In order to decrease the temperature in the hot spots identified in the pebble beds, a reduction of the Li₄SO₄ and beryllium bed volumes has been adopted. As for the structural material, the thermo-mechanical analyses have been assessed with respect the RCC-MR design code (completed for irradiation damages with ITER SDC-IC). The results reveal some problematic points in the base design, concentrated in the coolant inlet and outlet pipes and in the connection region of the BU cooling plates with the BU backplate. Submodeling technique has been used to improve the design in these regions. An increase in the thickness of the coolant inlet and outlet pipes and a redesign of the BU backplate have led to a fulfillment of the codes and standards. The design modifications of pebble bed region and structural material have been implemented in the final design of the BU that is presently used as reference for the design and test of a BU mockup in KIT.     

Radioactive waste assessment for the IFMIF/EVEDA facility

During the IFMIF/EVEDA phase, a 125 mA and 9 MeV deuterons prototype accelerator will be designed and tested for the final IFMIF project. During operation of the accelerator deuteron losses will occur in several components leading to material activation induced by deuteron and/or by secondary neutrons, depending on its location. This work is focused on a first radioactive waste assessment at the end of the operational life of this facility. The radioactive wastes generation will be evaluated, focusing on the beam dump and main accelerator components. Following the current approach to the back-end of the activated materials, they will be categorized according to radiological complexity of operations and final management routes. For the calculations, MCUNED and ACAB codes were used together with TENDL-2010 and EAF-2007 data libraries, respectively.     

Natural and artificial casings as bacteriocin carriers for the biopreservation of meats products

The aim of the study was to determine if natural and artificial casings (ovine, porcine, bovine, collagen, and cellulose casings), serve as carriers for the application of the bacteriocin sakacin G produced by Lactobacillus curvatus ACU‐1. Mode of action of the cell‐free supernatant (CFS) containing the bacteriocin was also studied to determine whether Listeria monocytogenes inhibition could be tantamount to Listeria innocua one. Cylindrical vessels were filled with sterile meat emulsion and were wrapped with the different casings. Half the systems were treated with the CFS containing sakacin G, while the other half was taken as control systems. All systems were inoculated with L. innocua ATCC 33090. L. innocua was able to grow on all the studied casings. Collagen casing treated with CFS inhibited Listeria growth. A bacteriostatic effect was observed in the systems with porcine, ovine, bovine and cellulosic casings treated with CFS. The bacteriocin maintained its activity until the end of the trial. All casings were widely promising as antimicrobial application supports, being effective carriers to be used in a wide range of meat products.

Practical applications

Based on its advantageous characteristics, bacteriocins attracted considerable interest as natural food preservatives to extend shelf life and safety of meat and meat products. The application of sakacin G produced by Lactobacillus curvatus ACU‐1 on different natural and artificial casings would allow the preservation of a wide range of meat products that are stuffed into them, such as several types of sausages, wiener, salami, and mortadella, among others. The major advantage relies on its application, since it is not necessary to modify the production process or add extra wrappings to support the antimicrobial substance.     

Fitting semi‐empirical drying models using a tool based on wavelet neural networks: Modeling a maize drying process

Maize drying is an important process, especially for storage and conservation. For this study, the experimental stage was carried out using a forced convection dryer with air heated at different temperature conditions (306.05–441.85 K) and flow (0.13–0.256 m³/hr), totalizing 15 drying curves. Then the performances of the classic drying kinetics methodology and the approach proposed in this paper, in which the increase in moisture content of the product with time was represented combining exponential models and neural networks based on wavelets, were compared. Good performance was obtained in predictions using the proposed approach. One of the main differentials of the methodology adopted was the obtainment of a model that has a global predictive capacity, within the range of tested operating conditions, which can be used in predicting drying curves for different operating conditions.

Practical applications

The drying process is also one of the most widely used methods for preserving food, and has the advantage of reducing the costs of storage and transport because of the low volume and weight of the end product. During the last years, this topic has attracted a broad industrial interest, resulting in many research studies investigating the drying process. Usually, with regard to the classic approach for modeling of the drying process, the kinetics of drying curves obtained in different operating conditions is affected separately, that is, the parameters are estimated independently, resulting in different regression problems. With the classical approach, in general, it is not possible to obtain a comprehensive prediction model with regards to operating conditions. We have proposed an alternative modeling method. Aiming to obtain a modeling tool with an overall predictive ability, an approach for drying kinetics prediction that combines exponential models and neural networks was proposed. The proposed modeling method was able to predict drying curves for different operating conditions.     

Dynamics of job satisfaction around internal migrations: a panel analysis of young people in Britain and Australia

There is ample evidence that internal migration is a vehicle for upwards economic and social mobility, particularly amongst young educated people, with studies documenting favourable effects on objective labour market outcomes such as employment status, earnings and occupational standing. However, this literature has been more silent about the potential effects of internal migration on subjective measures of utility. In this paper I use panel data from Australia and Britain and panel regression models to examine whether and how internal migration is associated with young people’s self-reported job satisfaction, paying attention to the time dynamics underpinning the associations. This enables gaining a more holistic picture of the outcomes associated with internal migration during early adulthood. Key findings indicate that long-distance and work-motivated migrations have positive and statistically significant effects on the job satisfaction of young people in Britain and Australia, particularly amongst those who hold university degrees. Additionally, the results reveal time patterns in the ways in which job satisfaction and residential mobility intersect: long-term trends in job dissatisfaction can trigger internal migration, and internal migration can set long-term onwards trends in job satisfaction. I conclude by calling for further research on the outcomes of internal migration on subjective well-being leveraging the properties of panel data and using a life course approach.