Towards understanding beneficial effects of slow power ramps

The topic of pellet cladding interaction (PCI) in light water reactor (LWR) fuel rods is reviewed and further explored in this paper by considering the mitigating effect of slow ramps. To that end, a number of PCI mitigating mechanisms were considered in relation to several failure criteria, including peak stress, strain energy density and other cumulative damage formulations. Towards a tentative working hypothesis for PCI mitigation by low ramp rate, the results fuel codes simulations of some slow ramps that have been part of the 3rd SCIP MWS (Studsvik Cladding Integrity Program Modeling WorkShop) are used in the paper in order to support or question the applicability of different possible mechanisms, considered as potential mitigating factors in slow ramps. In addition, the results of out-of-pile biaxial tests on irradiated cladding are presented for a loading scheme that aimed at reproducing the stress rate conditions of a slow ramp; the relatively small contribution of stress relaxation during the power increase stage of a slow ramp that was noticed in code calculations was confirmed by the mechanical biaxial tests. Thus, the main outcome of the code calculations in the 3rd SCIP MWS and related SCIP studies coupled with the literature review was that slow ramps’ benefits cannot be explained by mechanical effects only and a hypothesis is proposed that is based on the protective role of the cladding inner oxide and the healing of its cracks during a slow ramp provided the corresponding fuel rod gap chemistry exists.     

Obsessive passion,competence, and performance in a project management context

Obsessive passion is when people have a strong inclination toward an activity that they like, find important, and in which they spend significant time, but also feel internal pressure to engage in. Prior research has demonstrated that obsessive passion typically brings several negative consequences. The present study nuances the picture by showing that there are indeed conditions when obsessive passion can be beneficial and that it has an important role for project management. It develops and tests hypotheses on the role of project leaders' obsessive passion for project goals. Results support that challenging goals are attained to a greater extent if the project leader scores high on obsessive passion. Such obsessive passion, in turn, is a result of the project leader's competence (positive relationship) and the team's competence (inverted U-shaped relationship). These results have important implications for theory and future research on passion, goal theory, and competence in projects.     

Options for improving the load matching capability of distributed photovoltaics: Methodology and application to high-latitude data

At high latitudes, domestic electricity demand and insolation are negatively correlated on both an annual and a diurnal basis. With increasing integration of distributed photovoltaics (PV) in low-voltage distribution grids of residential areas, limits to the penetration level are set by voltage rise due to unmatched production and load. In this paper a methodology for determining the impacts of three options for increased load matching is presented and applied to high-latitude data. The studied options are PV array orientation, demand side management (DSM) and electricity storage. Detailed models for domestic electricity demand and PV output are used. An optimisation approach is applied to find an optimal distribution of PV systems on different array orientations and a best-case evaluation of DSM and a storage model are implemented. At high penetration levels, storage is the most efficient option for maximising the solar fraction, but at lower overproduction levels, the impact of DSM is equal or slightly better. An east-west orientation of PV arrays is suggested for high penetration levels, but the effect of the optimised orientation is small. Without an optimised storage operation, the overproduced power is more efficiently reduced by DSM than storage, although this is highly dependent on the applied DSM algorithm. Further research should be focused on the DSM potential and optimal operation of storage.     

Study of decomposition of ferrite in a duplex stainless steel cold worked and aged at 450–500 °C

The influence of cold-deformation on ferrite decomposition in duplex stainless steel during heat treatment at 450–500 °C was investigated using micro-hardness measurements and transmission electron microscopy. It was found that cold-deformation can change the mechanism of the α → α + α′ phase separation in the ferrite from nucleation and growth to spinodal decomposition. This finding is discussed in terms of the influence of an increased dislocation density on coherency strains.     

Key factors for achieving project success in integration of automotive mechatronics

In this paper, we present a multiple case study on integration of automotive mechatronic components. Based on the findings, we identify that the root causes of problems in integration are largely related to decisions omitted in electronic strategy. We present and recommend use of checklists defining key factors to address in order to achieve successful integration projects in terms of cost and quality. Our recommendations are defined by checklists for critical decisions in areas: functionality, platform, integration, and stakeholder involvement. The recommendations are established based on practitioner experience and then validated in a multiple case study. Five cases of integration are studied for different heavy vehicles in one company, and the fulfillment of our recommendations is measured. Finally we define project success criteria and we compare the level of fulfillment with the project success in terms of time plan and resource consumption. The main contribution of this study is the validated recommendations, each including a set of checkpoints that defines recommendation fulfillment. We also present defining characteristics to identify a high-risk project. We provide a set of observable project properties and show how they affect project risk.     

The CPLEAR electromagnetic calorimeter

A large-acceptance lead/gas sampling electromagnetic calorimeter (ECAL) was constructed for the CPLEAR experiment to detect photons from decays of π⁰s with momentum p_π⁰ ≤ 800 MeV/c. The main purpose of the ECAL is to determine the decay vertex of neutral-kaon decays K⁰ → π⁰π⁰ → 4γ and K⁰ → π⁰π⁰π⁰ → 6γ. This requires a position-sensitive photon detector with high spatial granularity in r−, −, and z−coordinates. The ECAL - a barrel without end-caps located inside a magnetic field of 0.44 T - consists of 18 identical concentric layers. Each layer of 1/3 radiation length (X₀) contains a converter plate followed by small cross-section high-gain tubes of 2640 mm active length which are sandwiched by passive pick-up strip plates. The ECAL, with a total of 6X₀ has an energy resolution of and a position resolution of 4.5 mm for the shower foot. The shower topology allows separation of electrons from pions. The design, construction, read-out electronics, and performance of the detector are described.     

Exergonomics of an EOR (OCDOPUS) project

The combined production of power, carbon dioxide, process steam, hot water, and compressed nitrogen for EOR is considered. Exergy-flow diagrams are used to evaluate plant efficiency. The exergy efficiency of the plant is defined as the sum of the exergy outputs divided by the exergy of the consumed fuel. Estimations of the invested exergy, net exergy coefficient and the sum of the specific exergy consumption are presented.     

Tandem Measurements of Aerosol Properties—A Review of Mobility Techniques with Extensions

When multiple instruments are used in tandem it is possible to obtain more complete information on particle transport and physicochemical properties than can be obtained with a single instrument. This article discusses tandem measurements in which submicrometer particles classified according to electrical mobility are then characterized with one or more additional methods. Measurement combinations that are summarized here include mobility plus mass, aerodynamic (or vacuum aerodynamic) diameter, integrated or multiangle light scattering, composition by single particle mass spectrometry, electron microscopy, and so on. Such measurements enable intercomparisons of different measures of size including mobility diameter, optical size, aerodynamic diameter, volume (for agglomerates and nanowires), length (for nanowires), and mass, even for particles that are morphologically and chemically complex. In addition, the article summarizes the use of tandem techniques to measure various transport properties (e.g., dynamic shape factor, sedimentation speed, diffusion coefficient) and physicochemical properties (e.g., mixing state, shape, fractal dimension, density, vapor pressure, equilibrium water content, composition). In addition to providing an overview of such tandem measurements we describe previously unreported results from several novel tandem measurement methods.