Algorithmisation of nuclear installations equipment dismantling

The standardised structure of cost items for decommissioning was issues jointly by OECD/NEA, IAEA and European Commission in 1999 for promoting of harmonisation in decommissioning costing. The computer code OMEGA, developed recently by the company DECOM, a.s. in Slovakia, implements this standardised structure of cost items as the base of an universal cost calculation structure for evaluation and optimisation of cost, exposure and other parameters for decommissioning options. The paper focuses on selected modules of the code which were developed for modelling of dismantling of systems, decontamination of building surfaces and demolition of structures. Evaluation of these activities is one of the most important tasks to be done prior to performance of decommissioning activities. Selection of proper techniques for these activities depends on category of the item to be dismantled, decontaminated or demolished (material composition, construction, type of building surface, etc.), local radiological conditions (dose rate, contamination), local working conditions (constraints), and other factors. Local radiological conditions and pre-defined limits of dose rate determine the selection of manual or remote techniques. Dismantling, decontamination of building surfaces and demolition activities include also set of preparatory and finishing activities. Extent of these auxiliary activities varies when performed within or outside of the controlled area and/or when performed manually or remote. Paper presents the approach for selection of the techniques for decommissioning activities and extent of auxiliary activities which was implemented in the OMEGA code, using the standardised cost structure as the cost calculation structure.     

Evaluation of the thiamine dose-response relationship for lake trout (Salvelinus namaycush) fry using an individual based model

Substantial natural reproduction of lake trout (Salvelinus namaycush) has not been achieved in the Great Lakes, except for Lake Superior and a few areas in Lake Huron, despite continued stocking efforts. Low thiamine levels in lake trout eggs, which can result in lethal and sublethal impacts (thiamine deficiency complex, TDC) on fry, may contribute to widespread recruitment failure in lake trout populations. We hypothesized that incorporation of sublethal impacts into dose-response curves would result in estimates of EC50s (median lethal concentrations) for fry greater than the estimates that rely only on acute mortality and that predation would exacerbate thiamine effects. To investigate the sublethal effects of TDC (prey capture success and predation mortality) on cohort growth and survival, we developed an individual-based model for lake trout fry. The model tracks daily activities, including consumption, respiration, growth, and mortality, of lake trout from hatch until fry reach a length of 33?mm when we assume fry feed naturally and thiamine effects are minimized. Model output with sublethal impacts resulted in an EC50 (7.3?nmol/g) that was greater than published studies that are limited to acute mortality (1.5?nmol/g). Furthermore, when we included interstitial and pelagic predation, the impact of sublethal effects shifted the EC50 values even higher (7.4–10?nmol/g). Simulation results indicate that low thiamine levels, in combination with moderate to high predation, can eliminate lake trout cohorts. Our simulations suggest that the sublethal effects of low thiamine can contribute to poor lake trout recruitment more than previously suspected.     

TRE+: Extended Tree‐Based Routing Ethernet

Tree‐based routing Ethernet (TRE) is a recent Ethernet architecture that enables shortcut links to improve performance compared to spanning tree protocols. However, TRE can only use shortcuts that arrive directly at bridges located in the branch of the destination. TRE+ extends the topology knowledge of a bridge to 2 hops away, thus unveiling new shortcuts to the destination branch. Simulations show a major performance improvement of TRE+ compared to TRE, with results close to shortest paths in some topologies.     

Lattice Relaxation and Dislocation Reduction in MBE CdTe(211)B/Ge(211)

We have used x-ray diffraction to assess the thickness dependence of strain in molecular-beam epitaxial (MBE) CdTe(211)/Ge(211). For 25-nm-thick layers, we find tensile stress of 100 MPa and in-plane strain of ~1.5 × 10⁻³. This stress relaxes during growth and becomes zero beyond 1 μm. We use the Dunn and Koch formula to estimate the threading dislocation density from the full-width at half-maximum of the (224) rocking curve. We then estimate the annihilation radius of MBE-grown CdTe(211)B/Ge(211) to be ~10 nm. Our layers have etch pit densities between 5 × 10⁷ cm⁻² and 5 × 10⁶ cm⁻² for a thickness of 10 μm. The lowest densities were obtained by periodic annealing epitaxy. We discuss mechanisms for the saturation of the dislocation density.     

Determination of Crystal Axes in Semimetallic T′‐MoTe2 by Polarized Raman Spectroscopy

Distorted octahedral T′ phase of MoTe₂ has recently attracted significant interest due to its predicted topological states and novel charge transport properties. Here, we report a nondestructive method for determining the crystal orientation of few‐layer T′‐MoTe₂ flakes by polarized Raman spectroscopy. The experimentally observed Raman modes are assigned to eigenmodes of vibrations predicted by density functional theory calculations. Polarized Raman measurements reveal four distinct types of angle‐dependent intensity variations. From group theory, it can be deduced that the intensity of the B_g mode reaches a maximum in the configuration when the polarization vector of the incident light is either parallel or orthogonal to the metal–metal zigzag chain direction. The intensity variation of the B_g mode cannot be used to unambiguously determine the crystal orientation. Using electron diffraction analysis, it is demonstrated that the intensity of the A_g mode at around 162 cm^?1 reaches a maximum when the polarization vector of the incident light is parallel to the metal–metal chain direction in the configuration. Furthermore, a simple method is proposed for identifying crystal orientation in nonpolarized Raman spectroscopy.     

Exploring the Leidenfrost Effect for the Deposition of High‐Quality In2O3 Layers via Spray Pyrolysis at Low Temperatures and Their Application in High Electron Mobility Transistors

The growth mechanism of indium oxide (In₂O₃) layers processed via spray pyrolysis of an aqueous precursor solution in the temperature range of 100–300 °C and the impact on their electron transporting properties are studied. Analysis of the droplet impingement sites on the substrate's surface as a function of its temperature reveals that Leidenfrost effect dominated boiling plays a crucial role in the growth of smooth, continuous, and highly crystalline In₂O₃ layers via a vapor phase‐like process. By careful optimization of the precursor formulation, deposition conditions, and choice of substrate, this effect is exploited and ultrathin and exceptionally smooth layers of In₂O₃ are grown over large area substrates at temperatures as low as 252 °C. Thin‐film transistors (TFTs) fabricated using these optimized In₂O₃ layers exhibit superior electron transport characteristics with the electron mobility reaching up to 40 cm² V^?1 s^?1, a value amongst the highest reported to date for solution‐processed In₂O₃ TFTs. The present work contributes enormously to the basic understanding of spray pyrolysis and highlights its tremendous potential for large‐volume manufacturing of high‐performance metal oxide thin‐film transistor electronics.     

Organic Bionics: A New Dimension in Neural Communications

The term “bionics” is synonymous with the term “biomimetics” and in this context refers to the integration of human engineered devices to take advantage of functional mechanisms and structures resident in nature. The use of electrical conductors to transmit charge into and out of biological systems to affect biological processes has been the source of great scientific interest. This has inspired many to explore the possible use of electrical stimulation in promoting positive health outcomes. Advances in medical bionics technology are dependent upon eliciting precise control of the electrical energy to deliver beneficial health outcomes. The advent of carbon‐based organic conductors now provides the platform for unprecedented possibilities by which the electrical energy can be used to modulate the function of medical devices. The use of organic conductors in the field of bionics, and in particular medical bionics, as that involved with the development of devices that enable the effective integration of biology (nature) and electronics to achieve a targeted functional outcome is explored.     

Study of the Coupling of Terahertz Radiation to Heterostructure Transistors with a Free Electron Laser Source

High electron mobility transistors can work as room-temperature direct detectors of radiation at frequency much higher than their cutoff frequency. Here, we present a tool based on a Free Electron Laser source to study the detection mechanism and the coupling of the high frequency signal into the transistor channel. We performed a mapping over a wide area of the coupling of 0.15 THz radiation to an AlGaN/GaN transistors with cut-off frequency of 30 GHz. Local, polarization-dependent irradiation allowed us to selectively couple the signal to the channel either directly or through individual transistor bias lines, in order to study the nonlinear properties of the transistor channel. Our results indicate that HEMT technology can be used to design a millimeter-wave focal plane array with integrated planar antennas and readout electronics.     

Refining Energy Levels in ReS2 Nanosheets by Low‐Valent Transition‐Metal Doping for Dual‐Boosted Electrochemical Ammonia/Hydrogen Production

Electrocatalytic nitrogen reduction reaction (NRR) and hydrogen evolution reaction (HER) are intriguing approaches to nitrogen fixation and hydrogen production under ambient conditions, given the need to discover efficient and stable catalysts to light up the “green chemistry” future. However, bottlenecks are often found during N₂/H₂O activation, the very first step of NRR/HER, due to energetic electron injection from the surface of electrocatalysts. It is reported that the bottlenecks for both NRR and HER can be tackled by engineering the energy level via low‐valent transition‐metal doping, simultaneously, where rhenium disulfide (ReS₂) is employed as a model platform to prove the concept. The doped low‐valent transition‐metal domains (e.g., Fe, Co, Ni, Cu, Zn) in ReS₂ provide more active sites for N₂/H₂O chemisorption and electron transfer, not only weakening the N?N/O? H bonds for easier dissociation through proton coupling, but also elevating d‐band center toward the Fermi level with more electron energy for N₂/H₂O reduction. As a result, it is found that iron‐doped ReS₂ nanosheets wrapped nitrogen‐doped carbon nanofiber (Fe‐ReS₂@N‐CNF) catalyst exhibits superior electrochemical activity with eightfold higher ammonia production yield of 80.4 µg h^?1 mg^?1_cat., and lower onset overpotential of 146 mV and Tafel slope of 63 mV dec^?1, when comparing with the pristine ReS₂.