Minimizing the Cost of Innovative Nuclear Technology Through Flexibility: The Case of a Demonstration Accelerator-Driven Subcritical Reactor Park

Presented is a methodology to analyze the expected Levelised Cost Of Electricity (LCOE) in the face of technology uncertainty for Accelerator-Driven Subcritical Reactors (ADSRs). It shows that flexibility in the design and deployment strategy of an ADSR park demonstrator significantly reduces its expected LCOE. The methodology recognizes in the conceptual design a range of possible technological outcomes for the ADSR accelerator system. It identifies flexibility “on” and “in” the design to modify the future development path in light of such uncertain scenarios. Uncertainty and flexibility are incorporated in the ADSR valuation. The resulting economic assessment is more realistic than typical discounted cash flow analysis that does not consider a range of development outcomes, or the flexibility to change development path

Fracture analysis of an electrically conductive interface crack with a contact zone in a magnetoelectroelastic bimaterial system

An electrically conductive interface crack with a contact zone in a magnetoelectroelastic (MEE) bimaterial system is considered. The bimaterial is polarized in the direction orthogonal to the crack faces and is loaded by remote tension and shear forces as well as electrical and magnetic fields parallel to the crack faces. It is assumed that the electrical field inside the crack faces is equal to zero and the magnetic quantities are continuous across the crack faces. Using special expressions of magnetoelectromechanical quantities via sectionally-analytic functions proposed in this paper, a combined Dirichlet-Riemann and Hilbert boundary value problem is formulated and solved analytically. Explicit analytical expressions for the characteristic mechanical, electrical and magnetic parameters are presented. A simple transcendental equation is derived for the determination of the contact zone length. Stress, electric field and magnetic field intensity factors and the contact zone length are found for various loading cases. A significant influence of the electric field on the contact zone length, stress and electric field intensity factors is observed. Magnetoelectrically permeable conditions in the crack region are also investigated and comparisons of different crack models are performed. Results presented in this paper should have potential applications to the design of multilayered magnetoelectroelastic (MEE) structures and devices.postprin

Pre-fracture zone model on magnetoelectrically permeable interface crack between two dissimilar magnetoelectroelastic materials

A plane strain problem for two magnetoelectroelastic (MEE) half-planes adhered by a thin isotropic interlayer is considered. A novel crack model, i.e., a magnetoelectrically permeable interface crack with pre-fracture zones is introduced for MEE bimaterial system. The stresses in pre-fracture zones and the lengths of pre-fracture zones are unknown, which are determined by solving the corresponding Hilbert problem and solving nonlinear equations introduced by yielding condition on the pre-fracture zones. Some particular cases are further analyzed and numerically discussed. In the suggested model, any singularities connected with the crack are eliminated, and the results presented in this paper should have potential applications to the design of multilayered MEE structures and devices. Copyright © (2013) by International Conference on Fracture.postprin

Moving crack with a contact zone at interface of magnetoelectroelastic bimaterial

The plane-strain problem of a moving crack at the interface of two dissimilar magnetoelectroelastic (MEE) materials is investigated. Assuming that the crack moves at a constant speed in the subsonic regime, a fracture analysis of a finite crack under concentrated loading imposed onto the crack face is first carried out. By applying magnetoelectric (ME) permeable boundary conditions at the crack face, a combined Dirichlet-Riemann problem is formulated and solved analytically. The expressions for the fracture parameters, including the relative length of the contact zone and field intensity factors (FIFs), are obtained in the analytical form. A crack of a semi-infinite length with a contact zone under concentrated loading is further presented as a specific case examined with the obtained solution. Then a moving crack of finite length at the interface under remote mix-mode loading is also analyzed and the corresponding fracture parameters are presented in an analytical form. Finally, numerical examples are provided for the material combination of barium titanate-cobalt ferrite composites to examine the influence of the speed of the moving crack, poling direction, material volume fraction, load position and load ratio on the fracture parameters, from which some new and interesting conclusions related to the crack model in this study are drawn

The extended finite element method with new crack-tip enrichment functions for an interface crack between two dissimilar piezoelectric materials

This paper studies the static fracture problems of an interface crack in linear piezoelectric bimaterial by means of the extended finite element method (X-FEM) with new crack-tip enrichment functions. In the X-FEM, crack modeling is facilitated by adding a discontinuous function and crack-tip asymptotic functions to the classical finite element approximation within the framework of the partition of unity. In this work, the coupled effects of an elastic field and an electric field in piezoelectricity are considered. Corresponding to the two classes of singularities of the aforementioned interface crack problem, namely, E class and class, two classes of crack-tip enrichment functions are newly derived, and the former that exhibits oscillating feature at the crack tip is numerically investigated. Computation of the fracture parameter, i.e., the J-integral, using the domain form of the contour integral, is presented. Excellent accuracy of the proposed formulation is demonstrated on benchmark interface crack problems through comparisons with analytical solutions and numerical results obtained by the classical FEM. Moreover, it is shown that the geometrical enrichment combining the mesh with local refinement is substantially better in terms of accuracy and efficiency.postprin

Amine molecular cages as supramolecular fluorescent explosive sensors: a computational perspective

We investigate using a computational approach the physical and chemical processes underlying the application of organic (macro)molecules as fluorescence quenching sensors for explosives sensing. We concentrate on the use of amine molecular cages to sense nitroaromatic analytes, such as picric acid and 2,4-dinitrophenol, through fluorescence quenching. Our observations for this model system hold for many related systems. We consider the different possible mechanisms of fluorescence quenching: Förster resonance energy transfer, Dexter energy transfer and photoinduced electron transfer, and show that in the case of our model system, the fluorescence quenching is driven by the latter and involves stable supramolecular sensor–analyte host–guest complexes. Furthermore, we demonstrate that the experimentally observed selectivity of amine molecular cages for different explosives can be explained by the stability of these host–guest complexes and discuss how this is related to the geometry of the binding site in the sensor. Finally, we discuss what our observations mean for explosive sensing by fluorescence quenching in general and how this can help in future rational design of new supramolecular detection systems

Economic Rationale for Safety Investment in Integrated Gasification Combined-Cycle Gas Turbine Membrane Reactor Modules

A detailed Net Present Value (NPV) model has been developed to evaluate the economic viability of an Integrated Gasification Combined Cycle – Membrane Reactor (IGCC-MR) power plant intended to provide an electricity generating and pure H2 (hydrogen) producing technology option with significantly lower air pollutants and CO2 (carbon dioxide) emission levels, where the membrane reactor module design conforms also to basic inherent safety principles. Sources of irreducible uncertainty (market, regulatory and technological) are explicitly recognized, such as the power plant capacity factor, Pd (palladium) price, membrane life-time and CO2 prices (taxes) due to future regulatory action/policies. The effect of the above uncertainty drivers on the project’s/plant’s value is elucidated using a Monte-Carlo simulation technique that enables the propagation of the above uncertain inputs through the NPV-model, and therefore, generate a more realistic distribution of the plant’s value rather than a single-point/estimate that overlooks these uncertainties. The simulation results derived suggest that in the presence of (operational, economic and regulatory) uncertainties, inherently safe membrane reactor technology options integrated into IGCC plants could become economically viable even in the absence of any valuation being placed on human life or quality of life by considering only equipment damage and interruption of business/lost production cost. Comparatively more attractive NPV distribution profiles are obtained when concrete safety risk-reducing measures are taken into account through pre-investment in process safety (equipment) in a pro-active manner, giving further credence to the thesis that process safety investments may result in enhanced economic performance in the presence of irreducible uncertainties.Process economic analysi

The host galaxies of luminous radio-quiet quasars

We present the results of a deep K-band imaging study which reveals the host galaxies around a sample of luminous radio-quiet quasars. The K-band images, obtained at UKIRT, are of sufficient quality to allow accurate modelling of the underlying host galaxy. Initially, the basic structure of the hosts is revealed using a modified Clean deconvolution routine optimised for this analysis. 2 of the 14 quasars are shown to have host galaxies with violently disturbed morphologies which cannot be modelled by smooth elliptical profiles. For the remainder of our sample, 2D models of the host and nuclear component are fitted to the images using the chi-squared statistic to determine goodness of fit. Host galaxies are detected around all of the quasars. The reliability of the modelling is extensively tested, and we find the host luminosity to be well constrained for 9 quasars. The derived average K-band absolute K-corrected host galaxy magnitude for these luminous radio-quiet quasars is =-25.15+/-0.04, slightly more luminous than an L* galaxy. The spread of derived host galaxy luminosities is small, although the spread of nuclear-to-host ratios is not. These host luminosities are shown to be comparable to those derived from samples of quasars of lower total luminosity and we conclude that there is no correlation between host and nuclear luminosity for these quasars. Nuclear-to-host ratios break the lower limit previously suggested from studies of lower nuclear luminosity quasars and Seyfert galaxies. Morphologies are less certain but, on the scales probed by these images, some hosts appear to be dominated by spheroids but others appear to have disk-dominated profiles.Comment: 16 pages, 8 figures, revised version to be published in MNRA

Design of a THz-MEMS frequency selective surface for structural health monitoring

This paper characterizes the relationship between applied force and reflectance/ transmittance of a terahertz frequency selective surface for use as a sensor in structural health monitoring. Numerical modelling of both the mechanical and electromagnetics, solving the elasticity equation and Maxwell’s equations, respectively, has been undertaken for a 3 layer device. The unit cell comprises of a metal cross wire embedded within a (hard) silicon substrate, interleaved with stacks of (soft) low density polyethylene